High-pressure synthesis, structure and properties of new ternary pnictides La3TiX5 (X = P, As)

Article abstract of DOI:10.1016/j.jallcom.2020.154697

The new ternary pnictides La₃TiX₅ (X = P, As) and the solid solutions of La₃Ti(Sb_1-xAs_x)₅ (x = 0–1) and La₃Ti(As_1-yP_y)₅ (y = 0–1) were synthesized under high pressure and high temperature conditions. The crystal structure of La₃TiX₅ (X = P, As) was determined from the X-ray powder diffraction data. These compounds crystallize in a hexagonal Hf₅Sn₃Cu-anti type structure with the space group P6₃/mcm and lattice parameters a = 8.7927 ? and c = 5.7643 ? for La₃TiP₅, and a = 9.0267 ? and c = 5.9071 ? for La₃TiAs₅, in which the face-sharing TiX₆ octahedral chains running along the c axis are separated by La³⁺ in the interstice sites with a distance about 9 ?, presenting a strong one-dimensional crystal structure. Physical properties measurements indicate La₃TiX₅ (X = P, As) are Pauli paramagnetic metals. The calculations reveal that La³⁺ ions are not perfectly ionic owing to the non-negligible contributions of La to the density of state (DOS) at the Fermi level and bridge the X atoms between the chains, which make the samples to be 3-dimensional metals. What's more, the change of X in La₃TiX₅ from Sb to P increases the ionicity of La³⁺ and thus decreases the electron hopping between the conducting chains.

Full text of DOI:10.1016/j.jallcom.2020.154697

Journal of Alloys and Compounds 831 (2020) 154697
Contents lists available at ScienceDirect
Journal of Alloys and Compounds
journal homepage: http://www.elsevier.com/locate/jalcom
High-pressure synthesis, structure and properties of new ternary
pnictides La3TiX5 (X ¼ P, As)
,
b
,
,
b
,
,
,
, b
Lei Duan a 1, Jun Zhang a 1, Xiancheng Wang a *, Jianfa Zhao a b, Lipeng Cao a
,
,
,
, b, d, ***
Wenmin Li a b, Zheng Deng a, Runze Yu a, Zhi Li c **, Changqing Jin a
a Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
b School of Physics, University of Chinese Academy of Sciences, Beijing, 100190, China
c College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
d Materials Research Lab at Songshan Lake, Dongguan, 523808, China
a r t i c l e i n f o
a b s t r a c t
Article history:
The new ternary pnictides La3TiX5 (X ¼ P, As) and the solid solutions of La3Ti(Sb1-xAsx)5 (x ¼ 0e1) and
La3Ti(As1-yPy)5 (y ¼ 0e1) were synthesized under high pressure and high temperature conditions. The
crystal structure of La3TiX5 (X ¼ P, As) was determined from the X-ray powder diffraction data. These
compounds crystallize in a hexagonal Hf5Sn3Cu-anti type structure with the space group P63/mcm and
lattice parameters a ¼ 8.7927 Å and c ¼ 5.7643 Å for La3TiP5, and a ¼ 9.0267 Å and c ¼ 5.9071 Å for
La3TiAs5, in which the face-sharing TiX6 octahedral chains running along the c axis are separated by La3þ
in the interstice sites with a distance about 9 Å, presenting a strong one-dimensional crystal structure.
Physical properties measurements indicate La3TiX5 (X ¼ P, As) are Pauli paramagnetic metals. The cal-
culations reveal that La3þ ions are not perfectly ionic owing to the non-negligible contributions of La to
the density of state (DOS) at the Fermi level and bridge the X atoms between the chains, which make the
samples to be 3-dimensional metals. What’s more, the change of X in La3TiX5 from Sb to P increases the
ionicity of La3þ and thus decreases the electron hopping between the conducting chains.
© 2020 Elsevier B.V. All rights reserved.
Received 16 December 2019
Received in revised form
6 March 2020
Accepted 7 March 2020
Available online xxx
Keywords:
One dimensional crystal structure
Metal
High pressure
Electronic band structure
1. Introduction
[6,10], RETi3Sb4 (RE ¼ Ce, Nd, Sm) [1,11], RE2Ti7Sb12 (RE ¼ La-Nd)
[11] and RE2Ti11-xSb14þx (RE ¼ Sm, Gd, Tb, Yb) [12]. These ternary
Ternary rare-earth 3d-transition metal pnictides RE-M-X (X ¼ P,
As, Sb, Bi) give rise to a vast class of materials adopting a plethora of
crystal structure types and displaying a wide variety of physical
properties [1e7]. The systems containing a late 3d-transition metal
are now relatively well known, whereas those containing an early
3d-transition metal remain poorly investigated. When M is V or Cr,
a few ternary compounds are known, such as REMSb3 (RE ¼ LaeNd,
Sm, Gd, Dy, Yb) and EuCr2As2 [7e9]. In the RE-Ti-Sb systems, sys-
tematic investigations have been reported and the existence of four
series of ternary phases is described: RE3TiSb5 (RE ¼ LaeNd, Sm)
compounds display complex crystal chemistry including TieTi and
SbeSb bonding interaction. In particular, RE3TiSb5 (RE ¼ LaeNd,
Sm), crystallizing into hexagonal Hf5Sn3Cu-anti type structure,
contains face-sharing TiSb6 octahedral chains and hypervalent Sb-
chains aligned along the c axis and separated by RE3þ and thus,
displays a strong one-dimensional crystal structure. It has been
reported that their magnetic properties result from the localized f-
electrons of rare-earth metal [13]. For the RE-Ti-Bi systems
(RE ¼ rare-earth metal), a few ternary compounds are reported in
the literature, such as RETi3Bi4 (RE ¼ La, Ce, Eu) [1,14], Eu3Ti8Bi10
[15] and RE3TiBi5 (RE ¼ La, Ce) [1,4]. However, in contrast to these
compounds with heavier pnicogen, no ternary phase in the RE-Ti-X
(X ¼ P, As) systems has been reported up to now.
* Corresponding author.
** Corresponding author.
Besides temperature and composition, pressure is another key
parameter to contribute increasingly to innovations in materials
sciences. The prominent effects of pressure are to shorten atomic
distance, to enhance charge transfer, and to initiate chemical re-
actions forbidden at ambient pressure. High pressure is capable to
*** Corresponding author. Beijing National Laboratory for Condensed Matter
Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
E-mail addresses: wangxiancheng@iphy.ac.cn (X. Wang), zhili@njust.edu.cn
(Z. Li), jin@iphy.ac.cn (C. Jin).
1
These authors contributed equally.
https://doi.org/10.1016/j.jallcom.2020.154697
0925-8388/© 2020 Elsevier B.V. All rights reserved.

2
L. Duan et al. / Journal of Alloys and Compounds 831 (2020) 154697
generate plenty of new materials or new phases, which can hardly
be synthesized under ambient pressure. Motivated in part by the
lack of information on titanium pnictides, we set out to conduct an
exploratory work in the LaeTi-X (X ¼ P, As) systems using high
pressure technique. Here, we report on the synthesis, crystal and
electronic structure, and physical properties of the new ternary
compounds of La3TiAs5 and La3TiP5, as well as the solid solutions of
La3Ti(Sb1-xAsx)5 (x ¼ 0e1) and La3Ti(As1-yPy)5 (y ¼ 0e1).
to obtain La3TiAs(P)5 at ambient pressure is complex and not just
the high vapor pressure of P and As.
Fig. 2(a) presents the sketch of crystal structure of La3TiX5
viewed with the projection along the [001] direction. The structure
consists of face-sharing TiX6 octahedral chains along the c axis,
which are arranged in a triangular lattice form. The X1 anions,
occupying the site of (x, 0, 1/4), surround the center ions of Ti to
form TiX6 octahedrons. Besides the TiX6 chains, the anions X2
located at the center of the triangular lattice with the site of (1/3, 2/
3, 0) are space-equally aligned along the c axis to form the X-chains.
The corresponding intrachain distance of X2-X2, is 2.8819 Å for
La3TiP5 and 2.9537 Å for La3TiAs5, which is a little larger than the
typical bond length of PeP (2.2e2.3 Å) [22] and AseAs (~2.5 Å) [23],
respectively. The moderate intrachain distance of X2-X2 suggests
the X2 anions in the linear X-chains are hypervalent with a formal
charge of X22ꢂ. The similar hypervalent Bi2ꢂ has been reported in
La3TiBi5 compound [4]. As for the interchain distances of X2-X2 and
X1-X2 shown in Table 2, they are so large enough that there is no
directly orbital overlap between each two chains of the X-chains
and TiX6 octahedral chains. Fig. 2(b) shows the partial structure for
La3TiX5, displaying the connection of TiX6 chains by face-sharing
LaX9 polyhedrons. There are nine X-ligands surrounding the cen-
ter La3þ ion, of which four X1 ligands come from the same TiX6
chain, one X1 ligands from the other TiX6 chain and the other four
X2 ligands come from the X-chains. The distances of LaeP in the
LaP9 polyhedron in La3TiP5 range from 2.9194 Å to 3.1228 Å, and the
bond lengths between the nine As-ligands and the center La3þ ions
in La3TiAs5 range from 3.0088 Å to 3.1878 Å. In addition, it is noted
that the corresponding distance of LaeLa in La3TiAs5 and La3TiP5 is
3.6726 Å and 3.5864 Å, respectively, which are comparable with the
interatomic distance in La metal (~3.65 Å) [24].
To further study the evolution of crystallographic data including
lattice, some important distances and angles from La3TiSb5 to
La3TiP5, we successfully synthesized the solid solutions of La3T-
i(Sb1-xAsx)5 (x ¼ 0e1) and La3Ti(As1-yPy)5 (y ¼ 0e1) under high
pressure and high temperature conditions. Fig. 3 (a-b, d-e) displays
the x-ray diffraction patterns of the solid solutions. When
increasing the doping level of x and y, the peaks shift monotonously
towards a high-angle direction, which demonstrates that the As
and P atoms are doped into La3TiSb5 and La3TiAs5, respectively. We
also carried out the refinements for the X-ray diffraction data of the
solid solutions of La3Ti(Sb1-xAsx)5 (x ¼ 0e1) and La3Ti(As1-yPy)5
(y ¼ 0e1) (see Figs. S1eS9 and Tables S1eS9). The lattice param-
eters a and c can be obtained from the refinements. The doping
dependence of lattice parameters is plotted as shown in Fig. 3(c, f).
The obtained lattice constants a ¼ 9.5265 (7) Å and c ¼ 6.2770 (5) Å
of La3TiSb5 agree with those reported in previous work [10]. These
lattice constants decrease linearly as the doping level x and y in-
crease. From La3TiSb5 to La3TiAs5 and to La3TiP5, the unit cell vol-
ume is shrunk by 15.6% and 21.9%, respectively.
2. Experimental
Commercially available lumps of La (Alfa, >99.999% pure), lumps
of As (Alfa, >99.999% pure), Sb powder (Alfa, >99.99% pure), P
powder (Alfa, >99% pure) and Ti powder (Alfa, >99.99% pure) were
used as the starting materials. The precursor LaX (X ¼ Sb, As and P)
were prepared by the reaction of La lumps and X powders at 700 ꢀC
in an evacuated quartz tube. We tried to synthesize La3TiX5 (X ¼ P,
As) at ambient pressure with the detail similar to that for La3TiSb5
[10]. However, we cannot obtain the samples of La3TiX5 (X ¼ P, As)
via ambient synthesis. Here, the La3Ti(Sb1-xAsx)5 (x ¼ 0e1) and
La3Ti(As1-yPy)5 (y ¼ 0e1) samples were synthesized successfully
under high pressure and high temperature conditions. The LaX, Ti
and X powders were mixed according to the elementary ratio of
stoichiometric La3TiX5, pressed into a pellet with a diameter of
6 mm, and then subjected to high-pressure synthesis under 5.5 GPa
pressure and 1000 ꢀC for 40 min in a cubic-anvil-type high-pres-
sure apparatus, of which the details have been reported in ref (16,
17) [16,17].
The X-ray diffraction (XRD) was conducted on a Rigaku Ultima
VI (3 KW) diffractometer using Cu Ka radiation generated at 40 kV
and 40 mA. The Rietveld refinements on the diffraction patterns
were performed using GSAS software packages [18]. The dc mag-
netic susceptibility measurement was carried out using a super-
conducting quantum interference device (SQUID). The resistance
was measured by four-probe electrical conductivity methods in
physical property measuring system (PPMS).
The first-principles calculations based on density functional
theory implemented in VASP were carried out within a primitive
cell with an 8 ꢁ 8 ꢁ 16 k-point grid [19]. The projector augmented
wave pseudopotentials with Perdew, Burke, and Ernzerhof (PBE)
exchange-correlation and 450 eV energy cutoff were used in our
calculation [20,21]. The experimental lattice parameters from XRD
were adopted.
3. Results and discussion
3.1. Crystal structure
Polycrystalline samples La3TiP5 and La3TiAs5 were prepared
under high-temperature and high-pressure conditions. Fig. 1(a and
b) displays the refinements for the XRDs of La3TiP5 and La3TiAs5,
respectively. Here, the structure of La3TiSb5 with the space group of
P63/mcm (193) was adopted as the initial model for the Rietveld
refinements [10], which smoothly converged to c2 ¼ 4.1, Rp ¼ 3.2%
and Rwp ¼ 5.2% for La3TiP5 and c2 ¼ 4.5, Rp ¼ 3.7% and Rwp ¼ 5.6% for
La3TiAs5. The summary of the crystallographic data is listed in
Table 1, and some selected important distances and angles are lis-
ted in Table 2. For comparing, the selected distances and angles of
isostructural La3TiSb5 and La3TiBi5 are listed in Table 2 as well. In
fact, we have tried the synthesis at ambient pressure via sealing the
precursors of LaAs(P), As(P) and Ti powders in an evacuated quartz
tube and sintering at different temperatures (800 ꢀC and 1000 ꢀC).
However, we didn’t obtain the samples of La3TiAs(P)5 at ambient
pressure. Since the quartz tube were intact during the ambient
pressure sintering process, it is speculated that the reason of failing
Fig. 4 presents the doping dependence of the bond angles
a of
X1-Ti-X1 in the TiX6 octahedrons (shown in Fig. 2(b)) and the dis-
tances of TieTi in TiX6 octahedral chains. The results reveal that all
the TiX6 octahedrons are slightly compressed along the c axis.
When X varies from large Sb atoms to smaller P atoms, the dis-
tances of TieTi decreases from 3.1385 Å to 2.8822 Å. For La3TiX5, the
TieTi distances are comparable with that in an elemental titanium
metal (~2.87e2.90 Å), which suggests that there exist bonding in-
teractions between corresponding Ti ions. In addition, the elec-
trostatic repulsion between Ti ions in the center of corresponding
face-sharing TiX6 octahedrons becomes stronger as the TieTi dis-
tance decreases, which tends to elongate the octahedrons. Thereby,
when X varies from Sb to P, the compression of TiX6 octahedrons is
partially released and the bond angles
a
increases from 87.329ꢀ to
88.697ꢀ, as shown in Fig. 4.

L. Duan et al. / Journal of Alloys and Compounds 831 (2020) 154697
3
Fig. 1. The X-ray diffraction patterns and the refinements with a hexagonal Hf5Sn3Cu-anti type structure and the space group of P63/mcm for (a) La3TiP5 and (b) La3TiAs5,
respectively.
Table 1
The summary of crystallographic data at room-temperature for La3TiP5 and La3TiAs5, respectively.
Hexagonal structure; Space group: P63/mcm, No.193
La3TiP5
La3TiAs5
a ¼ 8.7927 (4) (Å)
c ¼ 5.7643 (5) (Å)
c2 ¼ 4.1; Rp ¼ 3.2%
Rwp ¼ 5.2%
a ¼ 9.0265 (7) (Å)
c ¼ 5.9070 (6) (Å)
c2 ¼ 4.5; Rp ¼ 3.7%
Rwp ¼ 5.6%
Site
Wyck.
x
y
z
100 ꢁ U (Å)
La3TiP5
La
Ti
P1
P2
6g
2b
6g
4d
0.6213 (0)
0
0.2400 (4)
1/3
0
0
0
2/3
1/4
0
1/4
0
1.05 (9)
1.44 (0)
2.18 (6)
3.14 (2)
La3TiAs5
La
Ti
As1
As2
6g
2b
6g
4d
0.6216 (5)
0
0.2471 (9)
1/3
0
0
0
2/3
1/4
0
1/4
0
1.55 (6)
1.49 (4)
1.77 (1)
2.71 (1)
Table 2
0.1 m
U
-cm, which is comparable with the previous work [4]. The
-cm when Sb is
Selected distances (Å) and angles (ꢀ) between adjacent atoms. * denotes the intra-
value of rr increases more than fifty times to 5.7 m
U
chain distance and # denotes the interchain distance.(a) The data is from ref [4].
replaced by P. The replacement of Sb with higher electronegativity
of P should increase the ionic component of La3þ and reduce the
interchain electronic hopping, which will be discussed in following
calculations, and thereby increase the resistivity.
Fig. 5(b and c) displays the temperature dependence of mag-
netic susceptibility
susceptibility curves demonstrate paramagnetic like behavior. By
fitting the susceptibility within the whole measured temperature
region using modified Curie-Weiss law
is the susceptibility independent of temperature, C is the Curie
constant and Tq is the Weiss temperature, we can obtain the Curie
constant and estimate the effective moment meff, which are 0.60 mB
and 0.47 mB per molecular formula for La3TiP5 and La3TiAs5,
respectively. The small value of meff suggests that the paramagnetic
like behavior should arise from paramagnetic impurities. To sub-
tract the contribution from impurities, we fit the susceptibility of
low temperature region with Curie-Weiss law. After subtracting the
impurity contribution, we obtain the corrected susceptibility
~3.5 ꢁ 10ꢂ5 emu/mol for La3TiP5 and ~5.3 ꢁ 10ꢂ5 emu/mol for
La3TiAs5, which are almost temperature independent in the
La3TiX5
La3TiP5
La3TiAs5
La3TiSb5
(a)La3TiBi5
*TieTi ( ꢁ 2)
*X2-X2 ( ꢁ 2)
#X2-X2 ( ꢁ 3)
X1-X2 ( ꢁ 6)
La-X1 ( ꢁ 2)
La-X1 ( ꢁ 2)
La-X1 ( ꢁ 1)
La-X2 ( ꢁ 4)
LaeLa ( ꢁ 2)
Ti-X1 ( ꢁ 6)
2.8822
2.8822
5.0766
3.7073
3.1224
2.9179
3.3352
3.1076
3.5857
2.5557
88.679
91.321
2.9535
2.9535
5.2116
3.7594
3.1781
3.0051
3.3705
3.1902
3.6811
2.6841
87.531
92.469
3.1385
3.1385
5.5003
3.9605
3.3723
3.1856
3.5244
3.3672
3.8856
2.8543
87.329
92.671
3.2322
3.2322
5.5996
4.0253
3.4673
3.2645
3.5421
3.4291
3.9596
2.9373
87.255
92.745
c of La3TiX5 samples measured at 1 T. The
c
¼ c0 þ C/(T-Tq), where c0
X1-Ti-X1(
X1-Ti-X1(
a
b
)
)
3.2. Physical properties
The resistivity dependent on temperature for La3TiX5 samples
are presented in Fig. 5(a). All the resistivity curves exhibit a metallic
behavior. For La3TiSb5, the room temperature resistivity rr is about

4
L. Duan et al. / Journal of Alloys and Compounds 831 (2020) 154697
Fig. 2. (a) The crystal structure of La3TiX5 with the projection along c axis, showing the triangular lattice form and chain structure characteristic. (b) The partial structure for La3TiX5,
showing the bridge of LaX9 polyhedral between TiX6 octahedral chains and X-chains.
Fig. 3. (a) X-ray powder diffraction patterns of La3Ti(Sb1-xAsx)5 (x ¼ 0e1); (b) the enlarged view, exhibiting the peak shift; (c) the lattice parameter a and c versus doping level x; (d-
f) the X-ray powder diffraction patterns, enlarged view and lattice parameter vs doping level y for La3Ti(As1-yPy)5 (y ¼ 0e1), respectively.
measured temperature region, as shown in Fig. 5(b and c). Thus,
La3TiP5 and La3TiAs5 should be Paul paramagnetic metals, which
agrees with the work for the isostructural La3TiSb5 and will be
further confirmed by our following calculations about the local
moments for the system.

L. Duan et al. / Journal of Alloys and Compounds 831 (2020) 154697
5
3.3. Calculations
We have performed the first-principles calculations to obtain
more insight into the physical properties from the band structure
and partial density of state (PDOS) for La3TiP5 and La3TiAs5, as
shown in Fig. 6(a) and (b), respectively. These band structures are
similar to that of La3TiSb5 [4]. There are several bands crossing the
Fermi level along the c ꢁ axis including the
G-A path, HeK path and
L-M path, which suggests it is conducting along the chain direction.
In addition, there are three bands that cut the Fermi level in the K-
G
-M plane (perpendicular to the c ꢁ axis), which makes the elec-
tronic structure of La3TiX5 three-dimensional like. The calculations
show a three-dimensional conducting behavior for both La3TiP5
and La3TiAs5 although they have a strong 1D structure. In the
previous work about La3TiSb5, the calculation for the band struc-
ture of the [TiSb5]9- substructure gave a well-defined 1D con-
ducting characteristic if the effect of La atoms on the conducting
properties was ignored [25]. When considering the contribution of
La atoms, the later calculations displayed that La3TiSb5 is a 3D
metallic band structure. This is means that the addition of a La atom
to the calculations substantially changes the electronic structure,
Fig. 4. The angles of X-Ti-X (a) in TiX6 octahedrons and distances of TieTi in TiX6
octahedral chains.
Fig. 5. (a) The resistivity dependent on temperature for La3TiX5 (X ¼ P, As, Sb). (b) and (c) The susceptibility
La3TiAs5, respectively. The red dashed line is the fit for the curve vs temperature at low temperature. The blue line is the corrected magnetic susceptibility. (For interpretation of
the references to colour in this figure legend, the reader is referred to the Web version of this article).
c versus temperature with the applied magnetic field 1 T for La3TiP5 and
c

6
L. Duan et al. / Journal of Alloys and Compounds 831 (2020) 154697
In the plots of PDOS, we can see that although the contribution
of La to the DOS near the Fermi level is much less than that of Ti and
P/As, it cannot be non-negligible as same as La3TiSb5. It indicates
that, even in La3TiP5, the La3þ ions are not perfectly ionic and bridge
the conducting chains to cause the 3D metallic behavior. However,
compared with La3TiAs5, the spectral weight of La 5d state in
La3TiP5 shifts toward high energy and the DOS near the Fermi level
is suppressed, as shown in Fig. 5(c), which indicates that more
electrons derived from La-5d are lost. Thereby, the La3þ ions in
La3TiP5 become more ionic than that in La3TiAs5. This result leads to
a weaker connection between the conducting chains and results in
the increase of resistivity in La3TiP5, as has been observed in
Fig. 5(a). Finally, we calculated the localized moment of Ti atoms for
both La3TiP5 and La3TiAs5. It shows that the localized moment is
zero, which suggests that the small effective moment obtained
from susceptibility should come from paramagnetic impurities.
4. Conclusion
The compounds La3TiAs5 and La3TiP5 are the first ternary
phosphide and arsenide in the RE-Ti-X systems, which are syn-
thesized under high pressure and high temperature conditions. The
structure consists of face-sharing TiX6 octahedral chains and X-
chains along the c axis and these chains are bridged by La atoms.
Both the compounds are Paul paramagnetic metals. The calcula-
tions of band structure and DOS indicate that both La3TiAs5 and
La3TiP5 are metallic with a 3D characteristic. In the system of
La3TiX5, when X varies from Sb to P, the ionic component of La3þ
ions increases, which results in the decrease of the electron hop-
ping between the conducting chains and thereby the increase of
resistivity.
Declaration of competing interest
The authors declare that they have no known competing
financial interests or personal relationships that could have
appeared to influence the work reported in this paper.
CRediT authorship contribution statement
Lei Duan: Formal analysis, Investigation, Data curation, Writing
- original draft, Writing - review & editing, Visualization. Jun
Zhang: Formal analysis, Data curation, Writing - original draft,
Visualization. Xiancheng Wang: Conceptualization, Formal anal-
ysis, Writing - original draft, Writing - review & editing. Jianfa
Zhao: Data curation, Visualization. Lipeng Cao: Data curation,
Visualization. Wenmin Li: Data curation, Visualization. Zheng
Deng: Formal analysis, Writing - original draft. Runze Yu: Formal
analysis, Supervision. Zhi Li: Methodology, Software. Changqing
Jin: Conceptualization, Project administration, Formal analysis,
Writing - original draft, Resources.
Acknowledgments
Fig. 6. The calculations of band structure and partial DOS for (a) La3TiP5 and (b)
La3TiAs5. (c) The La 5d state for both samples.
We greatly appreciate the support of the National Key R&D
Program of China and the Natural Science Foundation of China
under grant no. 2018YFA0305700, 2017YFA0302900, 11974410 and
11534016.
which suggests that La3þ ions play a key role for La3TiSb5 being a 3D
metal [26]. In our calculations for La3TiX5 (X ¼ P and As), it was
found that the bands near the Fermi level are filled with the elec-
trons derived from La-5d, Ti-3d and P-3p (As-4p) orbital. In addi-
tion, the P-3p (As-4p) orbitals are hybrid with both La-5d and Ti-3d
orbitals, which makes the conducting paths in the ab-plane and
along the c axis.
Appendix A. Supplementary data
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.jallcom.2020.154697.

L. Duan et al. / Journal of Alloys and Compounds 831 (2020) 154697
7
[12] Haiying Bie, Arthur Mar, Ternary rare-earth titanium antimonides RE2Ti11-
xSb14þx (RE ¼ Sm,Gd, Tb, Yb), Inorg. Chem. 47 (2008) 6763e6770.
[13] M. Matin, R. Kulkarni, A. Thamizhavel, S.K. Dhar, A. Provino, P. Manfrinetti,
Probing the magnetic ground state of single crystalline Ce3TiSb5, J. Phys.
Condens. Matter 29 (2017), 145601.
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4