Synthesis and characterization of a family of structurally characterized dysprosium alkoxides for improved fatigue-resistance characteristics of PDyZT thin films

Article abstract of DOI:10.1021/ic048550b

Using either an ammoniacal route, the reaction between DyCl₃, Na⁰, and HOR in liquid ammonia, or preferentially reacting Dy(N(SiMe₃)₂)₃ with HOR in a solvent, we isolated a family of dysprosium alkoxides as [Dy(μ-ONep)₂-(ONep)] ₄ (1), (ONep)₂Dy[(μ₃-ONep)μ-ONep)Dy(ONep) (THF)]₂(μ-ONep) (2), (ONep)₂Dy[(μ₃-ONep) (μ-ONep)Dy(ONep)-(py)]₂(μ-ONep) (3), [Dy₃(μ ₃-OBu^t)₂(μ-OBu^t) ₃(OBu^t)₄(HOBu^t)₂] (4), [Dy₃(μ₃-OBu^t)₂(μ-OBu ^t)₃(OBu^t)₄(THF)₂] (5), [Dy₃(μ₃-OBU^t)₂(μ-OBu ^t)₃(OBu^t)₄(py)₂] (6), (DMP)Dy(μ-DMP)₄[Dy(DMP)₂(NH₃)]₂ (7), [Dy(η⁶-DMP)(DMP)₂]₂ (8), Dy(DMP) ₃(THF)₃ (9), Dy(DMP)₃(py)₃ (10), Dy(DIP)₃(NH₃), (11), [Dy(η⁶-DIP)(DIP) ₂]₂ (12), Dy(DIP)₃(THF)₂ (13), Dy(DIP)₃(py)₃ (14), Dy(DBP)₃(NH₃) (15), Dy(DBP)₃ (16), Dy(DBP)₃(THF) (17), Dy(DBP) ₃(py)₂ (18), [Dy(μ-TPS)(TPS)₂]₂ (19), Dy(TPS)₃-(THF)₃ (20), and Dy(TPS) ₃(py)₃ (21), where ONep = OCH₂CMe₃, OBu^t = OCMe₃, DMP = OC₆H₃(Me) ₂-2,6, DIP = OC₆H₃(CHMe₂) ₂-2,6, DBP = OC₆H₃(CMe₃) ₂-2,6, TPS = OSi(C₆H₅)₃, tol = toluene, THF = tetrahydrofuran, and py = pyridine. We were not able to obtain X-ray quality crystals of compounds 2, 8, and 9. The structures observed and data collected for the Dy compounds are consistent with those reported for its other congeners. A number of these precursors were used as Dy dopants in Pb(Zr_0.3Ti_0.7)O₃ (PZT 30/70) thin films, with compound 12 yielding the highest-quality films. The resulting Pb _0.94Dy_0.04(Zr_0.3Ti_0.7)O₃ [PDyZT (4/30/70)] had similar properties to PZT (30/70), but showed substantial resistance to polarization reversal fatigue.

Full text of DOI:10.1021/ic048550b

Inorg. Chem. 2005, 44, 1588−1600
Synthesis and Characterization of a Family of Structurally Characterized
Dysprosium Alkoxides for Improved Fatigue-Resistance Characteristics
of PDyZT Thin Films
Timothy J. Boyle,* Scott D. Bunge, Paul G. Clem, Jacob Richardson, Jeffrey T. Dawley,
Leigh Anna M. Ottley, Mark A. Rodriguez, Bruce A. Tuttle, Gabriel R. Avilucea, and Ralph G. Tissot
Sandia National Laboratories, AdVanced Materials Laboratory, 1001 UniVersity BouleVard SE,
Albuquerque, New Mexico 87105
Received October 15, 2004
Using either an ammoniacal route, the reaction between DyCl3, Na0, and HOR in liquid ammonia, or preferentially
reacting Dy(N(SiMe3)2)3 with HOR in a solvent, we isolated a family of dysprosium alkoxides as [Dy( -ONep)2-
(ONep)]4 (1), (ONep)2Dy[( 3-ONep)( -ONep)Dy(ONep)(THF)]2( -ONep) (2), (ONep)2Dy[( 3-ONep)( -ONep)Dy(ONep)-
(py)]2( -ONep) (3), [Dy3(
3-OBut)2( -OBut)3(OBut)4(HOBut)2] (4), [Dy3( 3-OBut)2( -OBut)3(OBut)4(THF)2] (5), [Dy3(µ3
OBut)2( -OBut)3(OBut)4(py)2] (6), (DMP)Dy( 6-DMP)(DMP)2]2 (8), Dy(DMP)3(THF)3
-DMP)4[Dy(DMP)2(NH3)]2 (7), [Dy(
(9), Dy(DMP)3(py)3 (10), Dy(DIP)3(NH3)2 (11), [Dy(
6-DIP)(DIP)2]2 (12), Dy(DIP)3(THF)2 (13), Dy(DIP)3(py)3 (14),
Dy(DBP)3(NH3) (15), Dy(DBP)3 (16), Dy(DBP)3(THF) (17), Dy(DBP)3(py)2 (18), [Dy( -TPS)(TPS)2]2 (19), Dy(TPS)3-
(THF)3 (20), and Dy(TPS)3(py)3 (21), where ONep OCMe3, DMP OC6H3(Me)2-2,6, DIP
OCH2CMe3, OBut
OC6H3(CMe3)2-2,6, TPS OSi(C6H5)3, tol toluene, THF tetrahydrofuran, and
pyridine. We were not able to obtain X-ray quality crystals of compounds 2, 8, and 9. The structures observed
µ
µ
µ
µ
µ
µ
µ
µ
µ
µ
µ
-
µ
µ
η
η
µ
)
)
)
)
OC6H3(CHMe2)2-2,6, DBP
)
)
)
)
py
)
and data collected for the Dy compounds are consistent with those reported for its other congeners. A number of
these precursors were used as Dy dopants in Pb(Zr0.3Ti0.7)O3 (PZT 30/70) thin films, with compound 12 yielding
the highest-quality films. The resulting Pb0.94Dy0.04(Zr0.3Ti0.7)O3 [PDyZT (4/30/70)] had similar properties to PZT
(30/70), but showed substantial resistance to polarization reversal fatigue.
Introduction
series of PLnZT thin films.1 From this study, we found that
the aliovalent cations maintain the high polarization, yield
square loops, and reduce fatigue on Pt/Si wafers. The
aliovalent cations can, because of their size, occupy either
or both the A- and B-site cations, acting as donor and
acceptor dopants, respectively.
Initially, because of their commercial availability, the
nitrate (NO3) derivatives of the lanthanide series were used
in the chemical solution route to these films. However, the
NO3 ligand has a rapid, large thermal decomposition pathway
that can cause major disruption in the final thin film. As has
been often reported, metal alkoxides are excellent precursors
for solution routes to ceramic materials. It was surprising
that there were only three structurally characterized dyspro-
sium alkoxides [Dy(OR)3] reported in the literature: Dy-
(OCH(CMe3)2)3(NCMe)2,2 Dy(OC5N(O-2))3(H2O)2‚H2O,3 and
[Dy(µ-OEtOMe)(OEtOMe)]10.4 Therefore, we undertook the
Lead zirconium titanate (PZT), a solid solution of lead
titanate and lead zirconate, is of current interest as a
ferroelectric material for use in nonvolatile random-access
memories in computers. One well-known disadvantage of
this material is that it rapidly fatigues (105 cycles) when
cycled on platinized silicon (Pt/Si) wafers. To overcome this
problem, lanthanum (La3+) is often added as a donor dopant
for the A-site lead (Pb2+) atoms. Although this works to
minimize the fatigue, it also has the undesired effect of
lowering the remanent polarization (Pr) of the resultant
PLaZT.1 Previously, we reported on the effects that the
lanthanide series (Ln3+) has on the polarization and dielectric
constant (ꢀ′) when singularly doped into PZT, forming a
* To whom correspondence should be addressed. Tel.: (505)272-7625.
Fax: (505)272-7336. E-mail: tjboyle@Sandia.gov.
(1) Boyle, T. J.; Clem, P. G.; Tuttle, B. A.; Brennecka, G. L.; Dawley, J.
T.; Rodriguez, M. A.; Dunbar, T. D.; Hammetter, W. F. J. Mater.
Res. 2002 17, 871.
(2) Hermmann, W. A.; Anwander, R.; Scherer, W. Chem. Ber. 1993, 126,
1533.
1588 Inorganic Chemistry, Vol. 44, No. 5, 2005
10.1021/ic048550b CCC: $30.25
© 2005 American Chemical Society
Published on Web 02/08/2005

ImproWed Fatigue Resistance of PDyZT Thin Films
redissolution of the NH3 adduct or the NH3-free adduct in the
appropriate solvent, followed by crystallization at low temperature
(-35 °C) or slow evaporation under an argon atmosphere.
(b) Amide. DyCl3 was reacted with 3 equiv of LiNR2 in diethyl
ether (Et2O), and the resultant precipitate was removed by
centrifugation (eq 2, Results and Discussion). The resulting pale
yellow powder was washed several times with hex, sublimed,
crystallized, and then used without further purification. X-ray quality
crystals were grown from hexanes and proved to be Dy(NR2)3,
which was isostructural with literature reports.6 The pure Dy(NR2)3
was reacted with the desired HOR in the respective solvent to isolate
the various species of interest (eq 3, Results and Discussion).
Crystals were grown by slow evaporation or cooling of the reaction
mixture to -35 °C. Yields were not optimized.
[Dy(µ-ONep)2(ONep)]4 (1). The synthesis used Dy(NR2)3 (2.0
g, 3.1 mmol) and HONep (0.96 g, 10.9 mmol) in 5 mL of tol.
Yield 0.84 g (60%). FT-IR (KBr, cm-1): 2953 (s), 2866 (s), 2811
(s), 2741 (m), 2696 (w), 1655 (m, br), 1611 (w), 1608 (w), 1560
(m), 1508 (s), 1479 (m), 1464 (m), 1411 (w), 1393 (m), 1364 (m),
1329 (w), 1259 (w), 1217 (w), 1125 (s), 1066 (m), 1039 (m), 1020
(m), 934 (w), 898 (w), 752 (w), 607 (w), 568 (w), 468 (w), 417
(w). Elemental analysis for C60H132Dy4O12: Calcd 42.50% C, 7.84%
H. Found 41.87% C, 7.66% H.
Dy3(µ3-ONep)2(µ-ONep)3(ONep)4(py)2 (3). The synthesis used
Dy(NR2)3 (1.0 g, 1.6 mmol) and HONep (0.48 g, 5.4 mmol) in 5
mL of py. Yield 0.52 g (67%). FT-IR (KBr, cm-1): 2952 (s), 2903
(m), 2865 (m), 2808 (m), 2692 (w), 1603 (m), 1479 (m), 1460
(m), 1445 (m), 1393 (m), 1360 (m), 1259 (w), 1219 (w), 1128 (s),
1060 (s), 1020 (s), 935 (w), 898 (w), 751 (w), 704 (w), 602 (w),
569 (w), 417 (w). Elemental analysis for C115H238Dy6N5O18: Calcd
46.75% C, 8.12% H, 2.37% N. Found 47.85% C, 7.20% H, 2.78%
N.
Dy3(µ3-OBut)2(µ-OBut)3(OBut)4(HOBut)2 (4). The synthesis
used Dy(NR2)3 (1.0 g, 1.6 mmol) and HOBut (0.40 g, 5.4 mmol)
in 5 mL of tol. Yield 0.42 g (63%). FT-IR (KBr, cm-1): 3440
(br), 2962 (s), 2922 (m), 2896 (m), 2863 (m), 1474 (w), 1459 (w),
1379 (m), 1357 (m), 1206 (s), 1007 (m), 942 (m), 902 (m), 762
(w), 528 (m, br), 475 (m). Elemental analysis for C44H101Dy3O11:
Calcd 40.84% C, 7.86. Found 40.67% C, 7.11% H.
synthesis and exploration of a series of systematically varied
Dy(OR)3 compounds as potential dopant precursors in
PDyZT.
Several synthetic routes were undertaken in an attempt to
generate this family of Dy(OR)3 compounds and the products
isolated proved by single-crystal X-ray diffraction to be 1
- 21 : [Dy(µ-ONep)2(ONep)]4 (1), (ONep)2Dy[(µ3-ONep)-
(µ-ONep)Dy(ONep)(THF)]2(µ-ONep) (2), (ONep)2Dy[(µ3-
ONep)(µ-ONep)Dy(ONep)(py)]2(µ-ONep) (3), [Dy3(µ3-
OBut)2(µ-OBut)3(OBut)4(HOBut)2] (4), [Dy3(µ3-OBut)2(µ-
OBut)3(OBut)4(THF)2] (5), [Dy3(µ3-OBut)2(µ-OBut)3(OBut)4-
(py)2] (6), (DMP)Dy(µ-DMP)4[Dy(DMP)2(NH3)]2 (7), [Dy-
(η6-DMP)(DMP)2]2 (8), Dy(DMP)3(THF)3 (9), Dy(DMP)3-
(py)3 (10), Dy(DIP)3(NH3)2 (11), [Dy(η6-DIP)(DIP)2]2 (12),
Dy(DIP)3(THF)2 (13), Dy(DIP)3(py)3 (14), Dy(DBP)3(NH3)
(15), Dy(DBP)3 (16), Dy(DBP)3(THF) (17), Dy(DBP)3(py)2
(18), [Dy(µ-TPS)(TPS)2]2 (19), Dy(TPS)3(THF)3 (20), and
Dy(TPS)3(py)3 (21), where ONep ) neo-pentoxide (OCH2-
CMe3), OBut ) tert-butoxide (OCMe3), DMP ) 2,6-dimethyl
phenoxide [OC6H3(Me)2-2,6], DIP ) 2,6-diisopropyl phe-
noxide [OC6H3(CHMe2)2-2,6], DBP ) 2,6-di-tert-butyl phe-
noxide [OC6H3(CMe3)2-2,6], TPS ) triphenylsiloxide [OSi-
(C6H5)3], tol ) toluene, THF ) tetrahdyrodfuran, and py )
pyridine.
Figures 1-20 are plots of 1-21 (note that X-ray quality
crystals of compounds 2, 8, and 9 were not isolated). Selected
representative species from this family of compounds were
used as aliovalent dopant precursors in PDyZT thin films.
The ferroelectric properties of the final ceramic PDyZT thin
films characterized during this study are also reported.
Experimental Section
All compounds described below were handled with rigorous
exclusion of air and water using standard Schlenk-line and glovebox
techniques. All solvents were stored under argon and used as
received (Aldrich) in sure-seal bottles, including hexanes (hex), tol,
THF, and py. The following chemicals were used as received
(Aldrich): DyCl3, Na0, LiN(SiMe3)2 (LiNR2), H-ONep, H-OBut,
H-DMP, H-DIP, H-DBP, and H-TPS. NH3(g) was used as
received (Tri-gas, Inc.).
FT-IR data were obtained on a Bruker Vector 22 Instrument
using KBr pellets under an atmosphere of flowing nitrogen.
Elemental analysis was performed on a Perkin-Elmer 2400 CHN-
S/O elemental analyzer.
Dy3(µ3-OBut)2(µ-OBut)3(OBut)4(THF)2 (5). The synthesis used
Dy(NR2)3 (0.25 g, 0.39 mmol) and HOBut (0.10 g, 1.4 mmol) in 5
mL of THF. Yield 0.65 g (71%). FT-IR (KBr, cm-1): 3448 (br),
2969 (s), 2928 (m), 2901 (m), 2863 (m), 1473 (m), 1467 (m), 1381
(m), 1371 (m), 1357 (m), 1240 (m), 1203 (s), 1181 (s), 1164 (m),
991 (s), 983 (s), 935 (s), 902 (s),879 (m), 764 (m), 741 (m), 5278
(m), 493 (m), 476 (m). Elemental analysis for C44H97Dy3O11: Calcd
40.97% C, 7.58, % H. Found 40.73% C, 7.69% H.
Dy3(µ3-OBut)2(µ-OBut)3(OBut)4(py)2 (6). The synthesis used
Dy(NR2)3 (1.0 g, 1.6 mmol) and HOBut (0.40 g, 5.4 mmol) in 5
mL of py. Yield 0.37 g (56%). FT-IR (KBr, cm-1): 2966 (s), 2924
(m), 2900 (m), 2868 (m), 1601 (w), 1442 (m), 1371 (m), 1355
(m), 1199 (s), 999 (s), 991 (s), 993 (s) 903 (m), 763 (m), 751 (m),
700 (s), 615 (w), 524 (m), 492 (m), 476 (m), 403 (w). Elemental
analysis for C46H91Dy3N2O9: Calcd 42.38% C, 7.04% H, 2.15%
N. Found 41.19% C, 6.75% H, 1.59% N.
Dy3(µ-DMP)4(DMP)5(NH3)2 (7). The synthesis used DyCl3 (2.5
g, 9.2 mmol), Na0 (0.64 g, 27.8 mmol), and H-DMP (3.9 g, 32
mmol) in 20 mL of tol. Yield 3.89 g (73.6%). FT-IR (KBr, cm-1):
3358 (w), 3282 (w), 3057 (w), 3024 (w), 2960 (s), 2960 (m), 2927
(m), 2868 (m), 1588 (w), 1458 (m), 1430 (s), 1382 (w), 1358 (w),
General Syntheses. (a) Ammoniacal. Following the ammoniacal
preparative route reported by Clark and co-workers for La(OAr)3
species,5 DyCl3 was reacted with 3 equiv of Na0 in NH3(l) at -78
°C, followed by addition of 3 equiv of the desired HOR dissolved
in tol (eq 1, Results and Discussion). From the powder isolated
after the mixture was warmed to room temperature, crystals of the
NH3 adducts were isolated by dissolution in tol and cooling to -35
°C. NH3-free species were isolated by refluxing of the powder
redissolved in tol, followed by drastic reduction of the volatile
portion of the reaction mixture and then cooling to -35 °C or slow
evaporation in a glovebox. THF and py adducts were isolated by
(3) Tesdeschi, C.; Azema, J.; Gornitzka, H.; Tisnes, P.; Picard, C. Dalton
Trans. 2003,1738.
(4) Westin, L. C.; Kritikox, M.; Caneschi, A. Chem. Commun. 2003, 1012.
(5) Butcher, R. J.; Clark, D. L.; Grumbine, S. K.; Vincent-Hollis, R. L.;
Scott, B. L.; Watkin, J. G. Inorg. Chem. 1995, 34, 5468.
(6) Hermmann, W. A.; Anwander, R.; Munck, F. C.; Scherer, W.; Dufaud,
V.; Huber, N. W.; Artus, G. R. J. Z. Naturforsch. B 1994, 49, 1789.
Inorganic Chemistry, Vol. 44, No. 5, 2005 1589

Boyle et al.
1332 (m), 1272 (s), 1208 (s), 1172 (w), 1147 (w), 1109 (w), 1042
(m), 931 (w), 887 (m), 862 (m), 824 (w), 803 (w), 793 (m), 748
(m), 731 (w), 689 (m), 614 (w), 568 (m), 556 (m), 467 (w).
Elemental analysis for C79H95Dy3N2O9: Calcd 55.68% C, 5.62%
H, 1.64% N. Found 56.33% C, 5.95% H, 1.58% N.
[Dy(η6-DMP)(DMP)2]2 (8). The synthesis used Dy(NR2)3 (0.25
g, 0.39 mmol) and H-DMP (0.17 g, 1.4 mmol) in 5 mL of tol.
Yield 0.45 g (55%). FT-IR (KBr, cm-1): 2969 (s), 2928 (m), 2901
(m), 2869 (m), 1467 (m), 1381 (m), 1371 (m), 1357 (m), 1240
(m), 1203 (s), 1181 (s), 1165 (m), 991 (s), 982 (s), 935 (s), 902
(s), 877 (m), 768 (m), 743 (m), 528 (m), 494 (m), 476 (m).
Elemental analysis for C24H27DyO3: Calcd 54.80% C, 7.49% H.
Found 55.87% C,5.98% H.
Dy(DMP)3(THF)3 (9). The synthesis used Dy(NR2)3 (0.25 g,
0.39 mmol) and H-DMP (0.17 g, 1.4 mmol) in 5 mL of THF.
Yield 0.23 g (32%). FT-IR (KBr, cm-1): 3068 (w), 3039 (w), 2958
(s), 2922 (s), 2854 (m), 1592 (m), 1564 (m), 1544 (w), 1516 (w),
1467 (s), 1450 (s), 1439 (s), 1428 (s), 1389 (w), 1381 (w), 1287
(s), 1265 (s), 1222 (m), 1092 (s), 916 (m), 848 (m), 803 (m), 760
(m), 704 (m). Elemental analysis for C36H51DyO6: Calcd 58.00%
C, 6.93% H. Found 49.01% C, 5.21% H.
Dy(DMP)3(py)3 (10). The synthesis used Dy(NR2)3 (1.0 g, 1.6
mmol) and H-DMP (0.67 g, 5.4 mmol) in 5 mL of py. Yield 0.20
g (24%). FT-IR (KBr, cm-1): 3135 (w), 3067 (w), 3035 (w), 3012
(w), 2959 (m), 2924 (s), 2854 (m), 2723 (w), 1597 (s), 1591 (s),
1572 (m), 1531 (m), 1545 (m), 1510 (m), 1476 (s), 1466 (s), 1442
(s), 1425 (s), 1342 (m), 1286 (s), 1242 (m), 1217 (m), 1155 (w),
1090 (s), 1069 (m), 1037 (s), 1004 (m), 991 (w), 915 (w) 873 (s),
858 (s), 804 (w), 756 (s), 748 (s), 703 (s), 622 (m), 603 (w), 562
(w), 533 (s), 488 (w), 469 (w), 415 (w), 407 (m). Elemental analysis
for C88H94Dy2N8O6: Calcd 62.73% C, 5.62% H, 6.65% N. Found
62.08% C, 5.82% H, 6.15% N.
Dy(DIP)3(NH3)2 (11). The synthesis used DyCl3 (5.0 g, 18
mmol), Na0 (1.3 g, 568 mmol), and H-DIP (3.3 g, 64 mmol) in
40 mL of tol. Yield 6.6 g (57%). FT-IR (KBR, cm-1): 2961 (s),
2914 (m), 2866 (m), 1589 (w), 1461 (m), 1431 (s), 1383 (w), 1360
(w), 1331 (m), 1273 (m), 1207 (m), 1146 (w), 1111 (w), 1043 (w),
888 (m), 862 (m), 793 (w), 762 (w), 748 (m). Elemental analysis
for C27H57DyN2O3: Calcd 52.35% C, 9.27% H, 4.52% N. Found
59.47% C, 7.82% H, 3.10% N.
[Dy(η6-DIP)(DIP)2]2 (12). The synthesis used Dy(NR2)3 (1.0 g,
1.6 mmol) and H-DIP (0.97 g, 5.4 mmol) in 5 mL of tol. Yield
0.71 g (33%). FT-IR (KBr, cm-1): 3367 (m), 3278 (w), 3055 (m),
3024 (w), 2960 (s), 2928 (m), 2867 (m), 1589 (m), 1459 (m), 1433
(s),1383 (m), 1360 (m), 1328 (s), 1267 (s), 1202 (s), 1182 (s), 1157
(w), 1146 (w), 1103 (s), 887 (s), 861 (s), 829 (m), 797 (m) 753 (s),
733 (m), 696 (m), 619 (w), 598 (w), 572 (m), 545 (m), 466 (w),
453 (w), 426 (m). Elemental analysis for C72H102Dy2O6: Calcd
62.28% C, 7.40% H. Found 62.42% C, 7.25% H.
Dy(DIP)3(THF)2 (13). The synthesis used Dy(NR2)3 (1.0 g, 1.6
mmol) and H-DIP (0.97 g, 5.4 mmol) in 5 mL of THF. Yield
0.33 g (26%). FT-IR (KBr, cm-1): 2960 (s), 2893 (m), 2863 (m),
1588 (m), 1461 (m), 1431 (s), 1381 (m), 1358 (m), 1331 (s),
1273 (s), 1210 (s), 111 (w), 1095 (w), 1042 (m), 1017 (m), 888
(s), 863 (s), 755 (s), 691 (m), 564 (m). Elemental analysis for
C44H67DyO5: Calcd 63.03% C, 8.05% H. Found 62.70% C, 8.35%
H.
Dy(DIP)3(py)3 (14). The synthesis used Dy(NR2)3 (1.0 g, 1.6
mmol) and H-DIP (0.97 g, 5.4 mmol) in 5 mL of py. Yield 0.53
g (34%). FT-IR (KBr, cm-1): 3064 (w), 2966 (s), 2955 (m), 2865
(m), 1597 (m), 1462 (w), 1443 (s), 1430 (s), 1380 (w), 1332 (s),
1270 (s), 1213 (s), 1154 (m), 1070 (w), 1037 (w), 1002 (w), 888
(m), 859 (m), 751 (s), 705 (s). Elemental analysis for C56H71-
DyN4O3: Calcd 66.50% C, 7.08% H, 5.54% N. Found 66.20% C,
7.05% H, 5.92% N.
Dy(DBP)3(NH3) (15). The synthesis used DyCl3 (2.5 g, 9.3
mmol), Na0 (0.64, 28 mmol), and H-DBP (6.7 g, 33 mmol) in 40
mL of tol. Yield 3.5 g (52%). Elemental analysis for C42H66-
DyNO3: Calcd 63.42% C, 8.36% H, 1.76% N. Found 66.47% C,
8.27% H, 0.5% N.
Dy(DBP)3 (16). The synthesis used Dy(NR2)3 (5.0 g, 7.8 mmol)
and H-DBP (2.4 g, 27.2 mmol) in 20 mL of tol. Yield 6.1 g
(50.4%). FT-IR (KBr, cm-1): 3646 (s), 3080 (m), 2957 (s), 2916
(s), 2872 (s), 1584 (m), 1478 (m), 1458 (s), 1425 (s), 1411 (m),
1387 (m), 1359 (m), 1309 (m) 1249 (s, br), 1196 (m), 1176 (m),
1144 (m), 1121 (m) 1098 (m), 1019 (w), 956 (w), 873 (s), 842
(m), 819 (m), 808 (m), 794 (m), 747 (s), 663 (s), 589 (m), 549
(m), 523 (w), 449 (m). Elemental analysis for C84H126Dy2O6: Calcd
64.81% C, 8.16% H. Found 38.97% C, 5.28% H.
Dy(DBP)3(THF) (17). The synthesis used Dy(NR2)3 (1.0 g, 1.6
mmol) and H-DBP (1.1 g, 5.4 mmol) in 5 mL of THF. Yield 0.30
g (23%). FT-IR (KBr, cm-1): 3081 (w), 3059 (w), 3003 (m) 2958
(s), 2919 (m), 2873 (m), 1476 (m), 1459 (m), 1426 (s), 1408 (s),
1388 (m), 1362 (m), 1314 (m), 1260 (s), 1248 (s), 1232 (s), 1199
(m), 1172 (m), 1141 (m), 1123 (m), 1106 (m), 1094 (m), 955 (w),
928 (w), 864 (m), 845 (m), 822 (m), 806 (m), 794 (m), 747 (s),
969 (m), 666 (w), 954 (m), 588 (w), 542 (m), 529 (w), 446 (w),
418 (w). Elemental analysis for C46H71DyO4: Calcd 64.96% C,
8.41% H. Found 65.68% C, 8.27% H.
Dy(DBP)3(py)2 (18). The synthesis used Dy(NR2)3 (1.0 g, 1.6
mmol) and H-DBP (1.1 g, 5.4 mmol) in 5 mL of py. Yield 0.15
g (11.3%). FT-IR (KBr, cm-1): 3080 (w), 3049 (w), 3002 (w, sh),
2958 (s), 2922 (m), 2871 (m), 1405 (s), 1261 (s), 1258 (s), 1229
(s), 1199 (m), 1101 (m), 1070 (m), 1041 (m), 1008 (m), 884 (w),
864 (s), 856 (s), 816 (s), 807 (s), 797 (s), 751 (s), 709 (s), 656 (m),
643 (m), 626 (m), 610 (m), 546 (w), 466 (w). Elemental analysis
for C52H73DyN2O3: Calcd 66.68% C, 7.86% H, 2.99% N. Found
67.08% C, 7.63, % H, 2.86% N.
[Dy(µ-TPS)(TPS)2]2 (19). The synthesis used Dy(NR2)3 (0.23
g, 0.36 mmol), TPS-H (0.3, 1.1 mmol) in 5 mL of tol. Yield 0.19
g (51%). FT-IR (KBr, cm-1): 3066 (s), 3049 (m), 3016 (m), 2963
(m), 2930 (m) 1261 (w), 1185 (w), 1158 (w), 1113 (s), 1067 (w),
1046 (w), 1035 (m), 1000 (m), 979 (m), 869 (w), 835 (w),
744 (m), 702 (s), 672 (w), 517 (s). Elemental analysis for C115H98-
Dy2O6Si6: Calcd 66.74% C, 4.77% H. Found 66.82% C, 5.34%
H.
Dy(TPS)3(THF)3 (20). The synthesis used Dy(NR2)3 (0.23 g,
0.36 mmol), TPS-H (0.3, 1.1 mmol) in 5 mL of THF. Yield 0.39
g (87%). FT-IR (KBr, cm-1): 3066 (s), 3049 (s), 3016 (m), 2963
(w), 2930 (w), 1433 (s), 1263 (m), 1187 (m), 1116 (s), 1068 (m),
1042 (w), 1028 (w), 1000 (m), 978 (s), 860 (m), 837 (w), 738 (m),
703 (s), 671 (m), 517 (s). Elemental analysis for C70H77DyO7Si3:
Calcd 65.83% C, 6.07% H. Found 65.74% C, 5.98% H.
Dy(TPS)3(py)3 (21). The synthesis used Dy(NR2)3 (0.23 g, 0.36
mmol), TPS-H (0.3, 1.1 mmol) in 5 mL of py. Yield 0.23 g (52%).
FT-IR (KBr, cm-1): 3062 (w), 3064 (s), 3044 (s), 3020 (m), 3006
(m), 2996 (m), 2963 (m), 2927 (m), 1599 (m), 1536 (w), 1482
(w), 1441 (s), 1427 (s), 1378 (w), 1262 (w), 1215 (w), 1186 (w),
1151 (w), 1109 (s), 1062 (m), 1033 (m), 1024 (m), 999 (m), 980
(s), 714 (m), 701 (s), 618 (w), 518 (s). Elemental analysis for
C69H60DyN3O3Si3: Calcd 67.60% C, 4.93% H, 3.43% N. Found
67.12% C, 5.08% H, 3.80% N.
General X-ray Crystal Structure Information.7 Each crystal
was mounted onto a thin glass fiber from a pool of Fluorolube and
immediately placed under a liquid N2 stream on a Bruker AXS
diffractometer. The radiation used was graphite monochromatized
1590 Inorganic Chemistry, Vol. 44, No. 5, 2005

ImproWed Fatigue Resistance of PDyZT Thin Films
Table 1. Data Collection Parameters for 1, 1a, and 3
Table 2. Data Collection Parameters for 4-6
1
1a
3
4
5
6
chemical formula
formula weight
temp (K)
C67H140Dy4O12 CaHbDycNadOe C115H238Dy6N5O18
chemical formula
formula weight
temp (K)
C44H101Dy3O11 C44H97Dy3O11 C46H91Dy3N2O9
1787.79
293(2)
-
223(2)
2954.10
168(2)
1293.75
168(2)
1289.72
203(2)
1303.74
203(2)
space group
tetragonal
Ph42(1)c
20.324(5)
20.324(5)
11.976(4)
tetragonal
I4/m
15.002(2)
15.002(2)
19.733(4)
monoclinic
C2/c
space group
monoclinic
P2(1)/c
19.369(2)
10.7734(13)
27.295(3)
orthorhombic monoclinic
Pbcn
C2/c
a (Å)
b(Å)
c (Å)
17.4909(17)
22.228(2)
18.1697(18)
94.911(2)
7038.3(12)
2
a (Å)
b(Å)
13.8708(17)
19.8030(19)
17.6311(18)
17.188(2)
19.665(2)
17.630(2)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
â (deg)
V (Å3)
4947(2)
2
1.200
4440.8(11)
-
-
4.221
99.308(2)
90.257(2)
Z
Dcalcd (Mg/m3)
µ (Mo KR) (mm-1
R1a (%) (all data)
1.394
3.198
5620.8(12)
4
1.529
5890.4(10)
4
1.546
5959.1(13)
)
3.026
-
-
5.025
2.64 (3.16)
9.89 (14.73)
27.73 (30.82)
6.11 (8.96)
15.64 (17.02)
D
calcd (Mg/m3)
wR2b (%) (all data) 7.19 (7.35)
µ (Mo KR) (mm-1
)
3.994
3.817
2
2
a R1 ) ∑||Fo| - |Fc||/∑ |Fo| x 100. b wR2 ) [∑w(Fo - Fc )2/
R1a (%) (all data)
3.98 (5.03)
5.83 (8.17)
12.18 (13.18) 33.12 (34.30)
11.55 (12.72)
2
∑(w|Fo| )2]1/2 x 100.
wR2b (%) (all data) 7.93 (8.43)
2
2
a R1 ) ∑||Fo| - |Fc||/∑|Fo| x 100. b wR2 ) [∑w(Fo - Fc )2/
Mo KR radiation (λ ) 0.7107 Å). The lattice parameters were
optimized from a least-squares calculation on carefully centered
reflections. Lattice determination and data collection were carried
out using SMART version 5.054 software. Data reduction was
performed using SAINT version 6.01 software. The structure
refinement was performed using XSHELL 3.0 software. The data
were corrected for absorption using the SADABS program within
the SAINT software package.
Each structure was solved using direct methods. This procedure
yielded the heavy atoms, along with a number of the C, N, and O
atoms. Subsequent Fourier synthesis yielded the remaining atom
positions. The hydrogen atoms were fixed in positions of ideal
geometry and refined within the XSHELL software. These idealized
hydrogen atoms had their isotropic temperature factors fixed at 1.2
or 1.5 times the equivalent isotropic U value of the C atoms to
which they were bonded. The final refinement of each compound
included anisotropic thermal parameters on all non-hydrogen atoms.
Additional information concerning the data collection and final
structural solutions of 1-21 can be found in the Supporting
Information. Any variations from standard structural solution
associated with the representative compounds, are discussed below.
Data collection parameters are listed in Tables 1-6.
2
∑(w|Fo| )2]1/2 x 100.
Table 3. Data Collection Parameters for 7 and 10
7
10
chemical formula
formula weight
temp (K)
C79H95Dy3N2O9
1704.07
223(2)
C88H94Dy2N8O6
1684.71
168(2)
space group
monoclinic
P2(1)
triclinic
P1h
a (Å)
b(Å)
11.758(2)
22.320(4)
14.171(3)
10.712(15)
13.799(20)
27.84(4)
81.94(2)
87.51(2)
74.07(2)
3918(9)
2
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
94.503(4)
3707.6(11)
2
D
calcd (Mg/m3)
1.526
1.428
µ (Mo KR) (mm-1
)
3.048
1.951
R1a (%) (all data)
9.63 (18.32)
14.85 (18.06)
6.29 (12.82)
9.87 (13.97)
wR2b (%) (all data)
2
2
a R1 ) ∑||Fo| - |Fc||/∑|Fo| x 100. b wR2 ) [∑w(Fo - Fc )2/
2
∑(w|Fo| )2]1/2 x 100.
Film Production. Standard spin-coat deposition routes8 were
used to generate the PDyZT thin films. A brief description of the
preparation and processing follows. The PZT (30/70) films were
produced following the established BRP route,8,9 in which Pb(O2-
CCH3)2‚(HO2CCH3) (Aldrich, 95%) dissolved in pyridine (py) was
added to a mixture of Ti(OCH(CH3)2)4 (Aldrich, distilled) and [Zr-
(OCH(CH3)2)4(HOCH(CH3)2)]2 (Aldrich) dissolved in tol to form
the PZT precursor mixture. Compound 12 was dissolved in py and
then added to the PZT mixture to form the ∼0.4 M PDyZT
precursor solution.
Multilayered films of the desired composition were spin-coat
deposited, in air, onto Pt(1700 Å)/Ti(300 Å)-coated, thermally
oxidized SiO2/Si substrates using a photoresist spinner (3000 rpm
for 30 s). After each deposition, the films were heated on a hot
plate (300 °C for ∼5 min) and allowed to cool to room temperature
before the deposition of the next layer. After the final layer received
the 300 °C treatment (for this study, 2-4 layers were used), the
film was crystallized in a tube furnace at 650 °C for 30 min in air.
X-ray diffraction (XRD) was used to confirm the phase purity and
orientation of the final films.
Ferroelectric Testing. To measure the electrical properties of
the films, gold top electrodes (∼250 × 250 µm) were sputter-
deposited onto the films using a shadow mask to create a parallel-
plate capacitor geometry. Capacitor top electrode areas were
individually measured with a calibrated optical microscope, and
film thicknesses were measured using a Dektak profilometer. The
low-field dielectric properties were measured at 10 kHz (100 mV
p-p) using an HP 4284A impedance analyzer (Palo Alto, CA).
The ferroelectric properties of the PLnZT films were measured using
an RT66A ferroelectric tester from Radiant Technologies (Albu-
querque, NM). Accelerated ferroelectric fatigue tests were per-
formed using a 1-MHz bipolar square-wave pulse, with the applied
electric field normalized to ∼700 kV/cm.
Results and Discussion
Because of our interest in doping PZT with aliovalent
lanthanide cations coupled with the dearth of readily available
acceptable Dy precursors, it was necessary to develop a
family of Dy(OR)3 compounds. As mentioned previously,
the nitrate derivatives, though convenient because they are
commercially available, do not always generate the highest-
(7) The listed versions of SAINT, SMART, XSHELL, XPOW in
SHELXTL, and SADABS Software from Bruker Analytical X-ray
Systems Inc., 6300 Enterprise Lane, Madison, WI 53719, were used
in analysis.
(8) Boyle, T. J.; Al-Shareef, H. N. J. Mater. Sci. 1997, 32, 2263.
(9) Boyle, T. J. U.S. Patent 5,858,451, 1991.
Inorganic Chemistry, Vol. 44, No. 5, 2005 1591

Boyle et al.
Table 4. Data Collection Parameters for 11-14
11
12
13
14
chemical formula
formula weight
temp (K)
C27H38.50DyN2O3
601.60
C72H102Dy2O6
1388.54
C44H67DyO5
838.48
C56H71DyN4O3
1010.67
168(2)
223(2)
168(2)
162(2)
space group
triclinic
P1h
monoclinic
P2(1)/c
17.105(18)
21.56(2)
9.669(10)
monoclinic
P2(1)
9.7320(13)
19.330(3)
12.1195(16)
monoclinic
Cc
18.503(3)
18.032(2)
15.808(2)
a (Å)
b(Å)
15.671(4)
20.199(6)
29.257(8)
105.495(4)
91.344(5)
111.208(4)
8245(4)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
105.84(2)
109.628(2)
96.811(2)
3430(6)
2
1.344
2.209
7.02 (12.69)
14.53 (17.17
2147.4(5)
2
1.297
1.780
2.34 (4.93)
2.80 (5.07)
5237.3(12)
4
1.282
1.471
4.93 (6.01)
9.98 (10.35)
8
D
calcd (Mg/m3)
0.969
µ (Mo KR) (mm-1
)
1.831
R1a (%) (all data)
8.26 (13.29)
22.69 (25.04)
wR2b (%) (all data)
a R1 ) ∑||Fo| - |Fc||/∑ |Fo| x 100. b wR2 ) [∑w(Fo - Fc )2/∑(w|Fo| )2]1/2 x 100.
2
2
2
Table 5. Data Collection Parameters for 15-18
15
16
17
18
chemical formula
formula weight
temp (K)
C42H66DyNO3
795.46
C84H126Dy2O6
1556.85
C46H71DyO4
850.53
C52H73DyN2O3
936.62
168(2)
168(2)
168(2)
178(2)
space group
monoclinic
P2(1)/n
monoclinic
P2(1)
orthorhombic
Pbca
orthorhombic
Pbcn
a (Å)
b(Å)
c (Å)
â (deg)
V (Å3)
Z
12.5879(12)
14.6871(14)
22.870(2)
105.696(2)
4070.5(7)
4
11.2323(8)
31.769(2)
11.5480(8)
104.9970(10)
3980.4(5)
2
20.130(6)
16.367(5)
26.234(8)
20.474(2)
13.7020(14)
17.5143(18)
8643(5)
8
1.307
1.768
5.39 (10.67)
7.90 (11.59)
4913.3(9)
4
1.266
1.561
4.27 (5.64)
8.11 (8.60)
D
calcd (Mg/m3)
1.298
1.299
µ (Mo KR) (mm-1
)
1.871
3.28 (4.09)
7.47 (7.79)
1.911
4.66 (5.62)
8.40 (8.87)
R1a (%) (all data)
wR2b (%) (all data)
2
2
2
a R1 ) ∑||Fo| - |Fc||/∑ |Fo| x 100. b wR2 ) [∑w(Fo - Fc )2/∑(w|Fo| )2]1/2 x 100.
Table 6. Data Collection Parameters for 19-21
Table 7. List of Structure Types Isolated for the Matrix of Ligands and
Solvents Used to Explore Dy(OR)3 Structuresa
19
20
21
ligand
NH3
tol
THF
py
chemical formula
formula weight
temp (K)
C
115H98Dy2O6Si6
C
70H77DyO7Si3
C
69H60DyN3O3Si3
ONep hexb
1 tetra (µ)
2d tri (µ and µ3, 2) 3 tri (µ and µ3, 2)
2069.47
168(2)
monoclinic
P2(1)/n
14.2341(15)
15.4455(16)
22.348(2)
91.675(2)
4911.2(9)
2
1277.09
168(2)
monoclinic
P2(1)
14.5532(15)
16.4016(17)
14.8835(15)
115.6790(10)
3201.8(6)
2
1.325
1.275
2.79 (3.00)
6.33 (6.41)
1225.97
203(2)
rhombohedral
R3m
22.937(5)
22.937(5)
12.123(5)
OBut
-
4 tri (µ and µ3) 5 tri (µ and µ3, 2) 6 tri (µ and µ3, 2)
c
DMP 7 linear tri (2) 8d di (π, 0)
DIP 11 mono (2) 12 di (π, 0)
DBP 15 mono (1) 16 mono (0)
9d mono (3)
13 mono (2)
17 mono (1)
20 mono (3)
10 mono (3)
14 mono (3)
18 mono (2)
21 mono (3)
space group
a (Å)
b(Å)
c (Å)
â (deg)
V (Å3)
Z
c
TPS
-
19 di (µ)
a The nuclearity is listed, and the type of interaction used by the ligands
to form the molecule and/or the number of solvent molecules bound are/is
in parentheses. b hex ) sodium contamination forms a poorly solved
hexameric species. c - ) never attempted. d No acceptable crystal solutions
reported. Proposed structure presented in parentheses.
5523(3)
3
1.106
1.104
6.40 (6.44)
16.19 (16.23)
D
calcd (Mg/m3)
1.399
1.639
4.86(7.13)
µ (Mo KR) (mm-1
)
R1a (%) (all data)
wR2b (%) (all data) 8.95 (9.55)
2
2
a R1 ) ∑||Fo| - |Fc||/∑|Fo| x 100. b wR2 ) [∑w(Fo - Fc )2/
and py when possible. The matrix used is shown in Table 7.
Once developed, representative compounds were used to
investigate the structural influences on the quality of the final
PDyZT thin films.
2
∑(w|Fo| )2]1/2 x 100.
quality films based on their large exothermic decomposition
pathways. Although there are numerous reports of Ln(OR)3
in the literature, the variety of ligands, cations, and solvents
used is diverse, and no systematic structural studies were
readily available to allow us to select an appropriate precursor
for our dopant investigation. Therefore, we synthesized and
isolated a series of Dy(OR)3 compounds that contained
increasing sterically demanding ligands, including H-ONep,
H-OBut, H-DMP, H-DIP, H-DBP, and H-TPS. In
addition, we are interested in how the solvents used will
affect their structure and isolated these species from tol, THF,
Synthesis. Several synthetic routes were undertaken in an
attempt to generate this family of Dy(OR)3 compounds: (a)
ammoniacal shown in eq 1 and (b) amide-alcohol metathesis
shown in eqs 2 and 3.
DyCl3 + 3Na0 + 3HOR NH3(l)8 Dy(OR)3 + 3NaCl + 3/2H2
(1)
DyCl3 + 3LiN(SiMe3)2 hex8 Dy(N(SiMe3)2)3 + 3LiCl (2)
1592 Inorganic Chemistry, Vol. 44, No. 5, 2005

ImproWed Fatigue Resistance of PDyZT Thin Films
tol8 Dy(OR)3 + 3HN(SiMe3)2
Dy(N(SiMe3)2)3 + 3HOR
9
(3)
5,10
Initially, the established ammoniacal route to Ln(OAr)3
was selected to generate the Dy(OAr)3 derivatives (eq 1).
X-ray quality crystals were isolated for 7, 11, and 15 which
were solved as the ammonia derivatives, adding to this ex-
clusive family of NH3-bound Ln compounds.5,10 Subsequent
solvated species of these precursors were isolated by redis-
solution of the appropriate aryloxide in the desired solvent.
Attempting a similar reaction with the alkyl alkoxides
using the ONep derivative led to a tetranuclear structure, 1
(Figure 1). However, attempts to crystallize the same powder
from THF yielded 1a (Figure 2), a highly disordered
hexanuclear species that is not charge balanced. Two
mechanisms are available to explain the structure of 1a: (i)
Na contamination is carried over from the original solution
and was not observed upon crystallization from tol or (ii)
the crystallization of 1 from THF can lead to an unusual
crystalline material that adopts a disordered structure. Ad-
ditional investigations to determine whether this is a con-
tamination or a crystallization disorder issue are underway.
However, because of the potential problems associated with
the ammoniacal route, we undertook the alternative amide-
alcohol synthetic route using Dy(NR2)3 (eq 3). Again, alkali
metal contamination was observed.
Figure 1. Plot of 1. Heavy atoms are thermal ellipsoids drawn at the 30%
level, and the carbon atoms are drawn in ball-and-stick format for clarity.
Dy(NR2)3 was obtained from the reaction of DyCl3 and 3
equiv of lithium amide.11 A series of solvent washes,
sublimations, and crystallizations led to the isolation of pure
Dy(NR2)3 exhibiting a crystal structure that agreed with the
literature report.6 The use of pure starting material is critical
to the isolation of high-quality crystals obtained in the next
step. All subsequent reactions involved the systematic
alcoholysis of Dy(NR2)3 in tol, as shown in eq 3. All further
solvated species discussed below were isolated by dissolution
of the product isolated from eq 1 or 3 in the appropriate
solvent or through eq 3 performed in the same solvent.
X-ray Structures. A matrix of the various ligands and
solvents used is shown in Table 7 with a summary of the
structural types identified. The discussion that follows details
the structures of the systematic family of Dy(OR)3 com-
pounds that have been synthesized and characterized.
neo-Pentoxide. From eq 3, using tol as the solvent, a
tetrameric structure was observed for 1 with a molecule of
tol observed in the lattice. Compound 1 is the first Dy-
(ONep)3 species isolated (Figure 1) wherein the central core
was found to be identical to the previously reported ONep
derivatives of La and Nd.10 The Dy metal centers are
arranged in a square shape interconnected by four bridging
µ-ONep ligands and one terminal ONep ligand per metal
center. Each of the Dy cations is five-coordinate, adopting
a square-base-pyramidal (SBP) geometry. As noted for the
La derivative, the ONep shows H-bonding, and additional
Figure 2. Ball-and-stick representation of 1a. Carbon atoms are omitted
for clarity.
work using this ligand and the remainder of the Ln cations
has revealed a consistent trend.12,13
Attempts to isolate 1 from THF did not lead to the
expected solvated adduct, but instead compound 1a was
solved. The central core of 1a is shown in Figure 2 and
exhibits a highly disordered “M6(O)(ONep)12” arrangement.
This zwitterion-like core consists of four metal atoms
arranged in a square, capped above and below by two
additional cations. Each of the six metal atoms is bound to
a µ6-O , four µ3-ONep, and one terminal ONep ligand. If all
of the metals are considered Dy, an overall 4+ charge exists,
and the model does not refine properly. Sodium atoms were
introduced to compensate for the charge as Na contamination
could have easily been introduced in the original reaction
(10) Barnhart, D. M.; Clark, D. L.; Gordon, J. C.; Huffman, J. C.; Vincent-
Hollis, R. L.; Watkin, J. G.; Zwick, B. D. Inorg. Chem. 1994, 33,
3487.
(11) Bradley, D. C.; Mehrotra, R. C.; Gaur, D. P. Metal Alkoxides;
Academic Press: New York, 1978.
(12) Boyle, T. J.; Ottley, L. M. Sandia National Laboratories, Albuquerque,
New Mexico. Unpublished work; 2004.
(13) Boyle, T. J. Sandia National Laboratories, Albuquerque, New Mexico.
Unpublished work; 2004.
Inorganic Chemistry, Vol. 44, No. 5, 2005 1593

Boyle et al.
Figure 3. Plot of 3. Heavy atoms are thermal ellipsoids drawn at the 30%
level, and the carbon atoms are drawn in ball-and-stick format for clarity.
Figure 4. Plot of 4. Heavy atoms are thermal ellipsoids drawn at the 30%
level, and the carbon atoms are drawn in ball-and-stick format for clarity.
and carried through the tol wash. Again, refinement of any
site as a full or partial Na atom occupation does not improve
the refinement. Alternatively, the observed structure of 1a
might be a result of a partially rotated molecule that
crystallizes in this orientation when THF is the solvent.
Numerous attempts to grow higher-quality crystals did not
improve the data or the subsequent model. Attempts to
isolated this compound from the amide synthesis (eq 3) have
not been successful (vide infra). However, 1a is often
observed in this and other Ln(ONep)3 systems we are
investigating with similar structural problems; therefore, the
structure and subsequent parameters of 1a are reported to
avoid mischaracterization of 1.
The amide-alcohol exchange route (eq 3) was then used
to synthesize the ONep derivative in the presence of Lewis
basic solvents (i.e., THF or py). For THF as the crystalliza-
tion solvent, a fully substituted tetranuclear species was
observed with THF in the lattice but not bound to the central
core or the structure of 1a (vide supra) was observed. Again,
it is possible to have a Li atom as a contaminant from eq 2,
and this led us to adopt the numerous purification steps for
Dy(NR2)3. From pure Dy(NR2)3, we have not been successful
in the isolation of a structure of the Dy(ONep)3 with bound
THF; however, upon switching to the stronger Lewis base
py, a trinuclear complex was solved as 3 (Figure 3). It is
assumed that 2 would be similar in structure to 3 based on
the other species isolated in this and other14,15 studies. For
3, the Dy cations are interconnected by two triply bridging
µ3-ONep and three bridging µ-ONep ligands. Two of the
Dy metal centers complete their distorted octahedral (Oh)
geometry by binding one terminal ONep ligand and a solvent
molecule, whereas the third Dy uses two ONep ligands. The
structure type observed here is similar to several other
lanthanide alkoxide trinuclear species previously reported but
the ligand sets of those compounds were typically OBut or
fluorinated species.14-19 It is of note that only two previous
Ln(OR)3 structures have been reported with coordinated py
as the solvent molecules, [Nd(µ-OR)(OR)2(py)]2 where OR
20
) OCH(CH(Me2)2)2 or OC6H2Me3-2,4,6.21
tert-Butoxide. Increasing the steric bulk of the pendant
alkoxide chain from ONep to OBut reduced the nuclearity
from the tetramer to a trimer when crystallized from tol. The
trimer of 4 (Figure 4) adopts an Oh arrangement using two
µ3-OBut, three µ-OBut, and six terminal OBut. Because of
charge balance, two free HOBut are necessarily bound to
the molecule. This structure is consistent with the [La-
(OBut)3]3(HOBut)2 structure reported by Bradley and co-
workers.16 Additional studies have shown that tetranuclear
species of Ln species with OBut as the ligand can be isolated
if there is no Lewis basic species present;12 however, this
was not realized with this system. Crystallization from THF
yielded simple substitution of the bound HOBut with THF
to form 5, shown in Figure 5, which is isostructural with
the Nd(OBut)3 derivatives isolated from THF.14,15 The py
adduct (6 shown in Figure 6) exhibits constructs similar to
those in 5 with the THF ligands replaced by py.
2,6-Dimethyl Phenoxide. As can be observed from the
increase in steric bulk from ONep to OBut, a decrease in
nuclearity was observed. Therefore, it was of interest to
determine the effect of di-ortho-substituted phenoxides on
the final structure, given that, from previous studies,22-24 we
(16) Bradley, D. C.; Chudzynska, H.; Hursthouse, M. B.; Motevalli, M.
Polyhedron 1991, 10, 1049-1059.
(17) Bradley, D. C.; Chudzynska, H.; Hursthouse, M. B.; Motevalli, M.;
Hammond, M. E.; Ruowen, W. Polyhedron 1992, 11, 375-379.
(18) Bradley, D. C.; Chudzynska, H.; Hursthouse, M. B.; Motevalli, M.;
Wu, R. W. Polyhedron 1993, 12, 2955-2960.
(19) Gun’ko, Y. K.; Elliot, S. D.; Hitchcock, P. B.; Lappert, M. F. J. Chem.
Soc., Dalton Trans. 2002, 1853.
(20) Barnhart, D. M.; Clark, D. L.; Huffman, J. C.; Vincent, R. L. Inorg.
Chem. 1993, 32, 4077.
(14) Gromada, J.; Chenal, T.; Morteux, A.; Ziller, J. W.; Leising, F. Chem.
Commun. 2000, 2183.
(15) Gromada, J.; Mortreux, A.; Chenal, T.; Ziller, J. W.; Leising, F. Chem.-
Eur. J. 2002, 8, 3773.
(21) Giesbrecht, G. R.; Gordon, J. C.; Clark, D. L.; Scott, B. L. Inorg.
Chem. 2002, 41, 6372.
(22) Boyle, T. J.; Andrews, N. L.; Rodriguez, M. A.; Campana, C.; Yiu,
T. Inorg. Chem. 2003, 42, 5357-5366.
1594 Inorganic Chemistry, Vol. 44, No. 5, 2005

ImproWed Fatigue Resistance of PDyZT Thin Films
Figure 7. Plot of 7. Heavy atoms are thermal ellipsoids drawn at the 30%
level, and the carbon atoms are drawn in ball-and-stick format for clarity.
The DMP-NH3 adduct 7 is shown in Figure 7 and was
isolated as a linear trinuclear species with each metal center
adopting an SBP geometry. Surprisingly, only one other Ln
structure had a linear trinuclear geometry, Eu[(µ-DMP)3Eu-
(THF)3]2.30 For 7, the central Dy uses four bridging DMP
and one terminal DMP ligands to form a trigonal-bipyramidal
(TBP) geometry. The terminal TBP-coordinated Dy atoms
link to two µ-DMPs, two terminal DMPs, and one NH3
group. This is in contrast to the Eu species discussed
previously, which has three bridging and three terminal THF
ligands. The variation in bound solvent is most likely
explained by the reduction in the Dy cation size.31 The
balance between the steric bulk of the DMP ligand combined
with the coordination of the Lewis basicity of the NH3 must
be too large to form the trinuclear arrangement14-19 but not
small enough to allow the dinuclear17,20,21,26 arrangement
noted for most lanthanide species.
Figure 5. Plot of 5. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
Removal of the NH3 through refluxing of a reaction
mixture of 7 in tol led to the isolation of 8. X-ray quality
crystals could not be isolated for this powder. From the
literature, there are ∼20 lanthanide structures that use an
aryloxide with two methyl groups present in the ortho
position;32 however, all of these compounds include coor-
dinated solvents, alternative ligands, or additional metal
centers. These variations tend to fill coordination sites
limiting the size of the molecules. It has been shown that a
reduction in the number of coordination sites by solvent
molecules leads to larger clusters {i.e., Y(DMP)3(THF)3
versus [Y(DMP)3(THF)]2}.33 Therefore, although it is dif-
ficult to predict the structure of 8 given that no homoleptic
Ln(DMP)3 without solvent coordination are available, two
structures have been proposed on the basis of available data.
One structure might be similar to 7 with the NH3 removed
Figure 6. Plot of the core of 6. Heavy atoms of the trinuclear species are
thermal ellipsoids drawn at the 30% level. The disorder in the O of the
terminal OBut and N of the py ligands leads to very large thermal ellipsoids,
so these atoms are represented as simple balls and left unassigned.
have found that the steric bulk of these ligands plays a pivotal
role in the final nuclearity. It was discerned that the
ammoniacal synthetic route using aryloxides produced high-
quality crystals that did not contain any Na contamination.
This was attributed to the increased steric bulk preventing
the need for filling of open coordination sites; however,
ammonia adducts are easily isolated. In the literature, only
a few ammonia lanthanide adducts have been reported,5,17,25-29
17,26
including [Pr(OC(CF3)3(NH3)2]2
and La(DIP)3(NH3)3.5
(23) Boyle, T. J.; Pedrotty, D. M.; Alam, T. M.; Vick, S. C.; Rodriguez,
M. A. Inorg. Chem. 2000, 39, 5133-5146.
(29) Zalkin, A.; Henly, T. J.; Andersen, R. A. Acta Crystallogr. C: Cryst.
Struct. Commun. 1987, 43, 233.
(24) Boyle, T. J.; Rodriguez, M. A.; Ingersoll, D.; Headley, T. J.; Bunge,
S. D.; Pedrotty, D. M.; De’Angeli, S. M.; Vick, S. C.; Fan, H. Chem.
Mater. 2002, 15, 3903.
(30) Evans, W. J.; Greci, M. A.; Ziller, J. W. Inorg. Chem. 2000, 39, 3213.
(31) Shannon, R. D. Acta Crystallogr. 1976, A32, 751.
(32) Twenty compounds were identified with three DMP ligands and any
lanthanide atom (La and Y) using the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ, United Kingdom,
www.ccdc.cam.ac.uk, which was searched using ConQuest v 5.25 (Apr
2004).
(25) Berg, D. J.; Anderson, R. A.; Zalkin, A. Organometallics 1988, 7,
1858.
(26) Bradley, D. C.; Chudzynska, H.; Hursthouse, M. B.; Motevalli, M.
Polyhedron 1994, 13, 7-14.
(27) Wang, K.-G.; Stevens, E. D.; Nolan, S. P. Organometallics 1992, 11,
1101.
(33) Evans, W. J.; Olofson, J. M.; Ziller, J. W. Inorg. Chem. 1989, 28,
4308.
(28) Wayda, A. L.; Dye, J. l.; Rogers, R. D. Organometallics 1984, 3, 1605.
Inorganic Chemistry, Vol. 44, No. 5, 2005 1595

Boyle et al.
Figure 10. Plot of 11. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
Figure 8. Schematic representation of proposed structures of 8: (a)
trinuclear species, (b) π-bound dinuclear species.
Figure 11. Plot of 12. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
characterized as 10 (Figure 9). Three solvent molecules bind
to form a mononuclear Oh-arranged species with an ad-
ditional molecule of solvent in the lattice for each.
Figure 9. Plot of 10. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
2,6-Diisopropyl Phenoxide. Using the increased steric
bulk of the DIP ligand in the ammoniacal synthesis, a
monomer, 11, coordinated by two NH3 molecules was
isolated. A plot of 11 is shown in Figure 10. Several DIP
lanthanide derivatives have been isolated, the majority of
which are mononuclear species through the coordination of
solvents.5,10,34,35 The distorted TBP geometry is unusual given
that there appears to be room to coordinate another NH3
molecule to form an Oh arrangement, as was noted for the
La(DIP)3 derivative that bound four NH3 molecules.5 Again,
the smaller size of the Dy cation in comparison to the La
as shown in Figure 8a. The lack of a Lewis base coupled
with the steric bulk of the DMP ligands stabilizing the open
coordination sites could lead to this type of structure;
however, there are no representative trinuclear structures in
the literature. The other structure might be similar to that of
the La(DIP)3 adduct and is schematically shown in Figure
8b.5 Because the coordination spheres of the Dy would be
filled and the larger structure exists, this is the preferred
structural arrangement. Further attempts to crystallize 8 from
THF also did not yield X-ray quality crystals either. On the
basis of literature reports,33 however, the powder was
assumed to be the monomer 9 and similar to what was
observed for the py adduct that was crystallographically
(34) Xie, Z. W.; Wang, S. W.; Zhou, Z. Y.; Mak, T. C. W. Organometallics
1998 17, 1907.
(35) Clark, D. L.; Gordon, J. C.; Watkin, J. G.; Huffman, J. C.; Zwick, B.
D. Polyhedron 1996, 15, 2279.
1596 Inorganic Chemistry, Vol. 44, No. 5, 2005

ImproWed Fatigue Resistance of PDyZT Thin Films
Figure 12. Plot of 13. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
Figure 14. Plot of 15. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
Figure 13. Plot of 14. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
Figure 15. Plot of 16. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
cation must account for the variation.31 Removal of the NH3
from 11 leads to the isolation of 12 (Figure 11), which adopts
a structure where the π-ring of the DMP coordinates to the
Dy, identical to what was observed for [La(η-DIP)(DIP)2]2.5
Lewis basic solvents reduce this interaction, forming the
TBP-coordinate monomer 13 with two axial THF solvent
molecules and the Oh-bound monomer 14 with three coor-
dinated py molecules, similar to what was noted for 10.
Figures 12 and 13 are plots of 13 and 14, respectively.
2,6-Di-tert-butyl Phenoxide. Using the most sterically
hindering ligand in our study (DBP), we isolated several
monomers, 15-18 (Figures 14-17, respectively). In the
presence of a Lewis base, Td-bound Dy ions were isolated
for NH3(l) (15) or THF (17) adducts, whereas a TBP
arrangement was noted for 18, which uses two py molecules.
This variation is most likely a representation of the stronger
Lewis basicity of py. A monomer was also isolated for the
reaction product of eq 3 run in tol. The Dy atom of
compound 16 adopts a trigonal geometry with no interaction
between the metal centers and the pendant aryl chains, as
noted for La. This is most likely due to the reduction in cation
size.31 Literature studies also show that other Ln-DBP-like
derivatives adopt mononuclear structures for solvated and
dinuclear for unsolvated compounds.36-38 The latter dinuclear
species was for the smaller Yb cation.
Triphenylsiloxide. We were also interested in how a
siloxane would affect structural aspects. Using the TPS
ligand, we isolated the dinuclear complex 19 from tol, which
contains Td-bound Dy atoms consisting of two µ-TPS and
(36) Stecher, H. A.; Sen, A.; Rheingold, A. L. Inorg. Chem. 1988, 27,
1130.
(37) van den Hende, J. R.; Hitchcock, P. B.; Holmes, S. A.; Lappert, M.
F. J. Chem Soc., Dalton Trans. 1995, 1435.
(38) van den Hende, J. R.; Hitchcock, P. B.; Lappert, M. F. Chem. Commun.
1994, 1413.
Inorganic Chemistry, Vol. 44, No. 5, 2005 1597

Boyle et al.
Figure 18. Plot of 19. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
Figure 16. Plot of 17. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
Figure 19. Plot of 20. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
Figure 17. Plot of 18. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
(π-bound or µ-OR) to mononuclear species as the steric bulk
is increased. In general, as the reduction in the amount of
steric bulk around the metal center is increased, the nuclearity
decreases. For the DIP aryloxides, the rings of the ligand
can act as a bridge because they are located relatively close
to the metal center, but this is not the case for the DBP or
the TPS ligands. For the former, the ortho substituents must
block any potential interactions, whereas for the latter, only
bridging through the oxygen occurs since the rings are too
far removed to induce the same interaction. All polynuclear
species are easily disrupted through the introduction of
solvents where the ability to displace another solvent follows
the Lewis base strength order of NH3 < THF , py. Again,
the degree of bound solvent is directly influenced by the
steric bulk of the ligand present. The metrical data of 1-21
are self-consistent and in-line with the values observed for
the other lanthanide species.2-6,10,14-21,25-29,34,35,42-44
two terminal ligands, similar to the constructs of the Ce
adduct.39 From THF, the monomeric species 20 was isolated
using three THF molecules and three TPS ligands to form
the Oh environment of the Dy cation. This is consistent with
the La,40 Ce,41 Pr,41 and Sm42 adducts. From py, a geometry
similar to that noted for THF was observed for 21 with py
replacing the THF molecules. Plots of the TPS-ligated species
19-21 are shown in Figure 18-20, respectively.
In summary, for the nonsolvated Dy(OR)3 compounds
characterized, the structures range from tetra- to tri- to di-
(39) Evans, W. J.; Golden, R. E.; Ziller, J. W. Inorg. Chem. 1991, 30,
4963.
(40) McGeary, M. J.; Coan, P. S.; Folting, K.; Streib, W. E.; Caulton, K.
G. Inorg. Chem. 1991, 30, 1991.
(41) Gradeff, P. S.; Yunlu, K.; Deming, T. J.; Olofson, J. M.; Doedens, R.
J.; Evans, W. J. Inorg. Chem. 1990, 29, 420.
(42) Xie, Z.; Chui, K.; Yang, Q.; Mak, T. C. W.; Sun, J. Organometallics
1998 17, 3937.
1598 Inorganic Chemistry, Vol. 44, No. 5, 2005

ImproWed Fatigue Resistance of PDyZT Thin Films
The Dy-O stretch could not be discerned from the numerous
peaks in the fingerprint region. Elemental analyses were also
collected for 1-21. The analyses appear to be in good
agreement with the crystal structures observed for the
majority of samples. Any variations are typically associated
with solvated species wherein preferential loss of bound
solvent or solvent molecules trapped in the lattice occurs.
Film Production. Approximately 0.4 M precursor solu-
tions to PbZr0.3Ti0.7O3 (PZT 30/70) were generated as
described in the Experimental Section, following the estab-
lished BRP process.1,8,9 The amount of Dy doping in the PZT
30/70 films was selected to be 4%, based on the highest
levels readily obtainable without secondary phase formation,
as previously noted for PLaZT studies. Because of the high
solubility of 12, this compound was used as the dopant for
the PDyZT (4/30/70). Films spin-coated from this solution
were visually high in quality with few visible defects
observed and were found to contain a single-phase, tetragonal
perovskite structure with lattice parameters a ) 3.99 Å and
c ) 4.12 Å with an approximate unit cell volume of ∼65.7
Å3. Diffraction patterns of the PDyZT perovskite phase
displayed a preference for the (111) out-of-plane orientation;
however, other (hkl) values were also observed. These results
are consistent with data collected on previous specimens.1,8
Figure 20. Plot of 21. Heavy atoms are thermal ellipsoids drawn at the
30% level, and the carbon atoms are drawn in ball-and-stick format for
clarity.
Bulk Evaluation. Because of the paramagnetic nature of
the Dy compounds, NMR (solution and solid state) spec-
troscopic data were not available. FTIR data were collected
for 1-21 using a KBr pellet press. These all show the
requisite stretches for the ligands used minus the OH stretch
(except for 4) and the appropriate solvent stretches and bends.
Figure 21. Hysteresis loops of PZT (30/70) (a) before (2) and (b) after (0) fatigue testing.
Figure 22. Hysteresis loops of PDyZT (4/30/70) (a) before (O) and (b) after ()) fatigue testing.
Inorganic Chemistry, Vol. 44, No. 5, 2005 1599

Boyle et al.
Figure 23. Plot of P* versus cycles for PZT and PDyZT.
The hysteresis loops prior to fatigue of PZT and PDyZT
are shown in Figures 21a and 22a, respectively. For PZT,
these loops were square and narrow with spontaneous
polarization (Pr) ) 24 µC/cm2, coercive field (Ec) ) 93 kV/
cm, ꢀ′ ) 396, and tan δ ) 0.007 (10 kHz, 100 mV). These
are reasonable values in comparison to our previous literature
reports.1,8,9 For the PDyZT films, comparable values were
obtained: Pr ) 26 µC/cm2, Ec ) 126 kV/cm, ꢀ′ ) 343, and
tan δ ) 0.009 (10 kHz, 100 mV). Although the films appear
to be very similar in initial properties, the fatigue behavior
was discovered to be substantially different between the two
films, presumably because of the inclusion of the amphoteric
Dy cations. It is believed that amphoteric dopants in
perovskites can occupy either the Pb or Zr/Ti site, thereby
suppressing the concentration of nonstoichiometry-related
oxygen vacancies, which are associated with ferroelectric
fatigue.1
The hysteresis loops after fatigue testing of PZT and
PDyZT are shown in Figures 21b and 22b, respectively. A
plot of the switched polarization (P*) versus number of
ferroelectric switching cycles is shown in Figure 23. In
contrast to the PZT film ,which fatigues around 107 cycles
(a substantial improvement over standard films, which
typically fatigue around 105 cycles at 250 kV/cm),1 the
PDyZT films showed almost no fatigue for up to 1011 cycles.
This is an impressive display of resistance to fatigue given
that the test was run at a field of 700 kV/cm, or roughly 2.5
times higher than the applied field used for the undoped
PZT.1 This resistance to fatigue due to Dy doping suggests
applications for such films in smart card and other nonvolatile
memory applications, where a 10-year lifetime might consist
of 1013 cycles. Resistance to voltage degradation of switching
properties might also be of interest for piezoelectric sensor
or optical switch applications, for which a long lifetime and
large number of polarization reversals can be required.
Summary and Conclusions
We have developed a comprehensive family of Dy(OR)3
compounds (1-21) synthesized by an amide-alcohol ex-
change or an ammoniacal preparative route. The final
structures of the isolated products exhibit a variety of
arrangements depending on the steric bulk of the ligands
introduced and the solvents used for crystallization. In
general, the smaller ligands (i.e., ONep or OBut) led to
oligomers such as tetramers and trimers, whereas larger
ligands (aryloxides or siloxides) led to dimers and monomers.
The construction of the ligand allows for either preferential
bridging or π-bonded bridging. For the monomeric species,
the coordination around the Dy metal center was controlled
by the amount of solvent bound, which was directly related
to the solvent’s Lewis basic strength. Compound 12 was
chosen as the dopant, and the resultant Pb0.94Dy0.04Zr0.30Ti0.70
(4/30/70) films were found to be substantially improved in
terms of fatigue in comparison to the undoped films. The
development of a number of new Dy precursors is hoped to
enable larger-scale studies of the exact mechanism of this
effect.
Acknowledgment. For support of this research, the
authors thank the Office of Basic Energy Sciences of the
Department of Energy and the United States Department of
Energy. Sandia is a multiprogram laboratory operated by
Sandia Corporation, a Lockheed Martin Company, for the
United States Department of Energy under Contract DE-
AC04-94AL85000.
Supporting Information Available: X-ray crystallographic files
in CIF format for the structures 1-21 (not available for 2, 8, and
9). This material is available free of charge via the Internet at
http://pubs.acs.org.
(43) Deacon, G. B.; Feng, T.; Nickel, S.; Ogden, M. I.; White, A. H. Aust.
J. Chem. 1992, 45, 1992.
(44) Giesbrecht, G. R.; Gordon, J. C.; Brady, J. T.; Clark, D. L.; Keogh,
D. W.; Michalczyk, R.; Scott, B. L.; Watkin, J. G. Eur. J. Inorg. Chem.
2002, 723.
IC048550B
1600 Inorganic Chemistry, Vol. 44, No. 5, 2005