Double Double to Double Perovskite Transformations in Quaternary Manganese Oxides

Article abstract of DOI:10.1002/anie.202108586

Control of cation ordering in ABX₃ perovskites is important to structural, physical and chemical properties. Here we show that thermal transformations of AA′BB′O₆ double double perovskites, where both A and B sites have 1:1 cation order, to (A_0.5A′_0.5)₂BB′O₆ double perovskites with fully disordered A/A′ cations can be achieved under pressure in CaMnMnWO₆ and SmMnMnTaO₆, enabling both polymorphs of each material to be recovered. This leads to a dramatic switch of magnetic properties from ferrimagnetic order in double double perovskite CaMnMnWO₆ to spin glass behaviour in the highly frustrated double perovskite polymorph. Comparison of double double and double perovskite polymorphs of other materials will enable effects of cation order and disorder on other properties such as ferroelectricity and conductivity to be explored.

Full text of DOI:10.1002/anie.202108586

Angewandte
Communications
Chemie
How to cite:
International Edition: doi.org/10.1002/anie.202108586
German Edition: doi.org/10.1002/ange.202108586
Perovskites
Double Double to Double Perovskite Transformations in Quaternary
Manganese Oxides
Kunlang Ji, Khalid N. Alharbi, Elena Solana-Madruga, Gessica T. Moyo, Clemens Ritter, and
J. Paul Attfield*
Abstract: Control of cation ordering in ABX3 perovskites is
important to structural, physical and chemical properties. Here
we show that thermal transformations of AA’BB’O6 double
double perovskites, where both A and B sites have 1:1 cation
order, to (A0.5A’0.5)2BB’O6 double perovskites with fully
disordered A/A’ cations can be achieved under pressure in
CaMnMnWO6 and SmMnMnTaO6, enabling both polymorphs
of each material to be recovered. This leads to a dramatic
switch of magnetic properties from ferrimagnetic order in
double double perovskite CaMnMnWO6 to spin glass behav-
iour in the highly frustrated double perovskite polymorph.
Comparison of double double and double perovskite poly-
morphs of other materials will enable effects of cation order
and disorder on other properties such as ferroelectricity and
conductivity to be explored.
large A+ and A’3+ cations. A second DDPv family with
columnar A-site and rock-salt B site orders has recently been
reported in RMnMnSbO6 (for rare earths R = La, Pr, Nd and
Sm)[12,13] and several CaMnBB’O6 materials (B = Mn, Fe, Co,
Ni for B’ = Re,[14–16] and B/B’ = Fe/Ta,[17] Cr/Sb and Fe/Sb[18]
)
synthesised at high temperatures and pressures. The A-site
order in this tetragonal P42/n family is driven by cation size
differences between R3+ or Ca2+ and Mn2+.
Alternative cation-ordered double perovskite and disor-
dered perovskite polymorphs have been synthesised for
several materials, with consequent changes in properties.
For example, the ferromagnetic Curie temperature where
colossal magnetoresistance is maximal changes from TC =
335 K in A-site layered LaBaMn2O6 to TC = 270 K for
cation-disordered (La0.5Ba0.5)MnO3,[19] and long range Fe3+/
Fe5+ charge order is observed in B-layered Ca2FeMnO6[20] but
not in disordered Ca(Fe0.5Mn0.5)O3.[21] This raises intriguing
questions of whether simple atomic order to disorder
transitions, which are of fundamental interest in systems
like b-brass (Cu0.5Zn0.5 alloy), can be observed for the
separate A and B cation pairs in double double perovskites,
and if so whether disorder in one sublattice induces disorder
in the other. The initial study found that RMnMnSbO6 double
double perovskites were formed for R = La, Pr, Nd and Sm,
P
erovskite oxides have remarkable flexibility in accepting
a wide variety of cations on the A- and B-sites leading to
many properties such as ferroelectricity, ferromagnetism and
superconductivity.[1–4] Further chemical variety arises through
cation ordering, and layered, columnar and rock-salt arrange-
ments have all been reported for the simplest 1:1 order at A or
B sites,[5] leading to AA’B2O6 or A2BB’O6 double per-
ovskite (DPv) structures. Such orders enable new physical
properties to emerge, notably ferrimagnetism and half-
metallicity with large magnetoresistance in Sr2FeMoO6 and
related A2BB’O6 DPvs[8] where rock-salt B/B’ ordering is
driven by cation charge and size differences.[9] Combined 1:1
orders at both A and B sites to give an AA’BB’O6 double
double (or doubly-ordered) perovskite (DDPv) are rarer but
[6]
[7]
whereas
A-site
disordered
double
perovskites
(R0.5Mn0.5)2MnSbO6 were formed for R = Eu and Gd, but
no double double—double phase coexistence or crossover
transition was observed.[12] Furthermore, a study of the
CaxMn2ÀxFeReO6 system discovered large chemical miscibil-
ity gaps between double perovskites near x = 0 and 2 and the
double double phase formed around x = 1 (CaMnFeReO6).[15]
Our continuing research recently produced the first evidence
of coexisting double and double double perovskites of the
same chemical composition in the CaMnMnWO6 and
SmMnMnTaO6 systems. These quaternary materials as rep-
resentative compositions from both A = Ca and R families
provide an ideal opportunity to study any coupling between
A-site and B-site cation orders in AA’BB’O6 double double
perovskites, as Mn2+ is common to both the A’ and B
sublattices so no A’/B disorder (observed in analogues such as
CaMnFeTaO6[17] and CaMnMSbO6; M = Cr, Fe[18]) can occur.
We report here that complete double double to double
perovskite structural phase transformations can be driven by
temperature in both the CaMnMnWO6 and SmMnMnTaO6
systems at pressure enabling both polymorphs of each
compound to be isolated, and we show that this structural
change leads to a dramatic switch in magnetic properties for
CaMnMnWO6.
two types are known. A family with A-site layered and B-site
[10]
rock-salt arrangements, for example, NaLaMgWO6
and
NaYNiWO6,[11] is stabilised by the charge difference between
[*] Dr. K. Ji, K. N. Alharbi, E. Solana-Madruga, G. T. Moyo,
Prof. J. P. Attfield
Centre for Science at Extreme Conditions (CSEC) and School of
Chemistry,University of Edinburgh
Mayfield Road, Edinburgh EH9 3JZ (UK)
E-mail: j.p.attfield@ed.ac.uk
E. Solana-Madruga
Univ. Lille, CNRS, Centrale Lille, Univ. Artois, UMR 8181, UCCS,
Unitꢀde Catalyse et Chimie du Solide
F-59000 Lille (France)
Dr. C. Ritter
Institut Laue-Langevin
38042 Grenoble Cedex (France)
Supporting information and the ORCID identification number(s) for
the author(s) of this article can be found under https://doi.org/10.
1002/anie.202108586.
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
ꢁ 2021 Wiley-VCH GmbH
1
These are not the final page numbers!

Angewandte
Communications
Chemie
CaMnMnWO6 and SmMnMnTaO6 samples were pre-
pared using stoichiometric mixtures of CaWO4 or SmTaO4
and MnO. CaWO4 was prepared by heating a stoichiometric
pellet of CaCO3 and WO3 for 24 hours at 11008C. SmTaO4
was prepared by heating a stoichiometric pellet of Sm2O3 and
Ta2O5 for 24 hours at 13508C, with the Sm2O3 dried in air at
9008C before use. The AMnMnB’O6 precursor mixtures were
packed into a Pt capsule and heated at temperatures ranging
from 1000 to 16008C under 10 GPa pressure in a Walker-type
multianvil apparatus. Samples were heated over 10 minutes to
the target temperature and held there for 30 minutes which is
sufficient to establish phase equilibrium, before quenching to
room temperature, after which the pressure was slowly
released.
Samples were analysed by powder X-ray diffraction data
collected at room temperature on a D2 Bruker diffractometer
in the angular range 2q = 10 to 1108 with step size 0.018 using
a Cu Ka source. Powder neutron diffraction patterns for
DDPv and DPv polymorphs of CaMnMnWO6 were collected
from ꢀ 200 mg samples using the D20 beamline at the ILL,
Grenoble. High-resolution data were collected at 300 K using
wavelength l = 1.54 ꢀ for structure refinement and scans at
1.5 and 80 K for the DDPv and at 1.5 and 10 K for the DPv
polymorph with l = 2.41 ꢀ were used to investigate magnetic
ordering. Magnetic symmetry analysis was carried out using
BASIREPS[22] and X-ray and neutron diffraction patterns
were refined through the Rietveld method using the Fullprof
Suite.[23] Magnetic susceptibilities and magnetization-field
hysteresis loops were measured on a Quantum Design
MPMS-SQUID magnetometer.
Double double perovskite phases of CaMnMnWO6 and
SmMnMnTaO6 were synthesised under 10 GPa pressure at
1000 and 12508C respectively. Fits to powder X-ray data
(Figures S1 and S2) confirmed that both compounds adopt
the tetragonal P42/n structure described above. However,
increasing temperature led to a mixture of double double
(DDPv) and double perovskite (DPv) phases as shown in the
powder X-ray data in Figure 1. All DDPv phases have the
tetragonal P42/n structure (Figure 2a) and the DPvs adopt the
monoclinic P21/n structure (Figure 2b) commonly found for
rocksalt-ordered A2BB’O6 double perovskites, e.g.
Ca2MnWO6.[24] Complete conversion to the DPv phase was
observed at 13008C for CaMnMnWO6 and at 16008C for
SmMnMnTaO6. Rietveld fits were used to extract the
proportions of each perovskite phase (shown in Table S1).
Figure 1. Powder XRD patterns of a) CaMnMnWO6 and
b) SmMnMnTaO6 at different synthesis temperatures showing prog-
ress of the DDPv-DPv structural phase transition. Black stars show
secondary phase contributions from CaWO4 in (a) or SmTaO4 in (b).
Figure 2. Crystal structures of a) P42/n double double perovskite
(DDPv) and b) P21/n double perovskite (DPv) AMnMnB’O6 structures.
Ordered A/Mn cations in the DDPv structure are shown as grey/red
spheres and Mn/B’O6 octahedra are blue/orange.
DPv
samples
of
(Ca0.5Mn0.5)2MnWO6
and
(Sm0.5Mn0.5)2MnTaO6 were, respectively synthesized at 1300
and 16008C, and X-ray fits are shown in Figures S1b and S2b
with results in Tables S2, S3, S7 and S8.
A/Mn disorders in the DDPv structure were refined in
initial Rietveld X-ray fits but in all cases no A-site disorder
was found to within ꢀ 1% refinement errors. Hence the
transformation from AMnMnB’O6 double double perovskite
with all cation sites fully ordered to (A0.5Mn0.5)2MnB’O6
double perovskites where A/Mn cations are fully disordered
over A-sites is discovered to occur entirely through a first
order transition via coexistence of the two phases, but without
any incipient A-cation disorder in either DDPv phase. The
first order nature of the transition reflects the incompatible
octahedral tilts between the two structures (Figure 2). The
P42/n DDPv structure has two in-phase and one out-of-phase
tilts of the B/B’O6 octahedra (written a+a+cÀ in Glazer
notation[25]) which creates the high (10) and low (4) oxide
coordination numbers around the A-site Ca/Sm and Mn
cations, respectively. However, the P21/n DPv structure has
one in-phase and two out-of-phase tilts (aÀaÀc+) that provide
a single 8-coordinate environment around all A cations. With
no group-subgroup relation between the two structures, the
transition is expected to be first order in Landau theory.
2
www.angewandte.org
ꢁ 2021 Wiley-VCH GmbH
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
These are not the final page numbers!

Angewandte
Communications
Chemie
Nevertheless, the magnitudes of tilt angles qxy in the xy-plane
nate) ionic radii of Ca2+ (1.12 ꢀ) and Sm3+ (1.08 ꢀ) are
and qz from the z-axis are virtually unchanged between the
DDPv and DPv structures; CaMnMnWO6 has qxy/qz = 17.3-
(1)/18.9(1)8 in DDPv and 18.3(1)/18.7(1)8 in DPv structures
from neutron refinement, and SmMnMnTaO6 has qxy/qz =
17.4(2)/19.0(3)8 in DDPv and 17.8(2)/18.7(3)8 in DPv from
X-ray refinement.
comparable, with the latter being closer in size to Mn2+
(0.96 ꢀ).[27] Assuming ideal statistical entropy changes of
Rln2 per mol of perovskite at the transitions due to the cation
disorder gives estimates of 8.8 and 10.0 kJmolÀ1 for the
enthalpy changes in CaMnMnWO6 and SmMnMnTaO6
respectively.
Despite the first order nature of the transition, the
average A-cation occupancy order parameter across the two
phases, calculated as QA = %DDPv/(%DDPv + %DPv)
using phase proportions from Table S1, shows a continuous
thermal variation for CaMnMnWO6 as shown in Figure 3.
This was fitted using the function QA = tanh(Wtb)/tanh(W),
where t = (TCÀT)/TC for temperatures T in K and W is
a fitting parameter to allow for higher order contributions to
the Landau free energy expansion at large t.[26] Initial
refinement gave b = 0.45(11) for CaMnMnWO6, consistent
with b = 0.5 from mean field theory, and the critical exponent
was fixed at the latter value giving the estimated upper
temperature for the A-site order to disorder transition in
CaMnMnWO6 as TC = 12608C. Fewer points are available for
SmMnMnTaO6 so the thermal variation is less clear, but a fit
of the same function with b = 0.5 gave TC ꢀ 14708C. The
higher transition temperature for SmMnMnTaO6 reflects the
charge difference between A-site cations, as the (8-coordi-
Rock-salt B-site ordering in DDPv and DPv materials
arises from cation size and charge differences. Previously
reported AA’BB’O6 DDPvs with B3+/B’5+ cation combina-
tions have large B/B’ antisite disorder, up to 18% in
CaMnFeTaO6.[17] B2+/B6+ combinations show much less dis-
order, for example, 4/3.6% for M = Co/Ni in CaMnMReO6,[16]
but no Mn/B’ antisite disorder to within refinement errors of
< 1% was observed in the X-ray studies of DDPv and DPv
phases of CaMnMnWO6 and SmMnMnTaO6 in all samples of
the present study. Hence the occupancy order parameter for
the B-cations is QB = 1 throughout as shown on Figure 3 so no
coupling between QA and QB is apparent from our X-ray
studies. Powder neutron refinement of the CaMnMnWO6
structures (Figure S4), where B/B’ antisite disorder is less
correlated with the scale factor than in X-ray refinements,
found no disorder for the DDPv sample synthesised at
10008C but gave 2.6(2)% Mn/W antisite disorder for the DPv
polymorph made at 13008C. This evidences a tiny influence of
A-cation disorder and increased temperature on the B-cation
ordering. Full neutron refinement results are in Tables S4 and
S5.
Magnetic properties of the DDPv and DPv polymorphs of
CaMnMnWO6 and SmMnMnTaO6 were measured to dis-
cover how they are affected by the change from A cation
order to disorder. High temperature susceptibilities of DDPv
and DPv polymorphs of CaMnMnWO6 in Figure 4a show
similar Curie–Weiss variations with fitted effective para-
magnetic moments of 8.64 and 8.45 mB per formula unit,
respectively, close to the theoretical value for high-spin 3d5
Mn2+ of 8.37 mB. Their respective Weiss temperatures are q =
À198 and À145 K showing that antiferromagnetic Mn2+ spin-
spin coupling is dominant, with some weakening of inter-
actions in the DPv structure due to disorder. However very
different ordering effects are apparent at low temperature.
DDPv-CaMnMnWO6 has a sharp Curie transition at TC =
45 K while the DPv polymorph shows a broader susceptibility
peak (identified below as a spin glass transition) at Tg = 8 K.
This indicates moderate magnetic frustration in the DDPv
material (frustration factor Àq/TC = 4.4) whereas the DPv
phase is highly frustrated (Àq/Tg = 18). Magnetisation-field
loops at 5 K in Figure S3 show small hystereses with
saturation moments of 0.05 and 0.03 mB and coercive fields
of 500 and 100 Oe for DDPv and DPv polymorphs, respec-
tively.
Low temperature neutron diffraction was used to explore
long range magnetic ordering in the two polymorphs of
CaMnMnWO6. For the DDPv phase magnetic diffraction
peaks indexed by propagation vector k = [0 0 0] appear below
the Curie transition. The magnetic intensities are fitted well
by a simple ferrimagnetic model in which A-site Mn2+ spins
are antiparallel to B-site spins (Figures S6 and S7). A slight
inequivalence of the opposed sublattice moments accounts
Figure 3. Cation occupancy order parameters Q from X-ray refine-
ments averaged over the DDPv and DPv structures for
a) CaMnMnWO6 and b) SmMnMnTaO6 plotted against synthesis tem-
perature. Error bars are smaller than the points. Fits of the function
described in the text to QA are shown, while QB =1 throughout as no
B-site disorder was observed.
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
ꢁ 2021 Wiley-VCH GmbH
www.angewandte.org
3
These are not the final page numbers!

Angewandte
Communications
Chemie
states to the paramagnetic moment. The fitted Weiss con-
stants of À217 and À156 K give frustration factors of 3.1 and
4.5 for the DDPv and DPv phases showing that both are
moderately frustrated, with greater frustration in the A-
cation disordered DPv polymorph. Magnetisation-field loops
at 5 K in Figure S3b show small saturation magnetisations of
0.01 and 0.03 mB for DDPv and DPv phases, and a change in
coercive field from 1700 Oe at 35 K to 400 Oe at 5 K shown in
Figure S3c is consistent with the likely Sm3+ moment ordering
transition at 18 K in DDPv-SmMnMnTaO6.
The above results demonstrate that P42/n-type AA’BB’O6
double double perovskites can be thermally transformed at
pressure to (A0.5A’0.5)2BB’O6 double perovskites in which A/
A’ cations are disordered but B/B’ remain fully ordered. The
transitions in CaMnMnWO6 and SmMnMnTaO6 are first
order and proceed entirely via coexistence of the DDPv and
DPv structures, without any incipient A/A’ disorder being
observed in the former. However the average A-site occu-
pancy order parameter across the two structures follows
a continuous mean field behaviour in CaMnMnWO6, ena-
bling the upper transition temperature to be estimated as
12608C (and near 14708C for SmMnMnTaO6). Both DDPv
and DPv polymorphs of each material can thus be recovered
by quenching under pressure from temperatures either side of
the transition, and this strategy is expected to be applicable to
many other double double perovskites provided the transition
temperature is within experimental limits.
Figure 4. a) Magnetic susceptibilities (ZFC/FC=open/filled circles)
and inverse ZFC susceptibilities (crosses) with Curie–Weiss fits (blue
lines) shown for DDPv (black symbols) and DPv (red symbols)
polymorphs of a) CaMnMnWO6 and b) SmMnMnTaO6. Inset to (a)
shows the spin glass transition of the DPv polymorph. Data were
collected in a 0.1 T field for both materials.
The ability to make double double and double perovskite
polymorphs of the same chemical composition is important as
it enables the effects of order or disorder of A/A’ cations on
physical properties such as magnetism in CaMnMnWO6 and
SmMnMnTaO6 to be directly compared. The rocksalt type
MnB’O6 B-site arrangement in these materials has an intrinsic
geometric frustration from networks of edge-sharing Mn4 spin
tetrahedra, and antiferromagnetic orders have been observed
in A2MnWO6 double perovskites below Nꢁel temperatures of
TN = 8, 8, 13 and 16 K respectively for A = Ba,[28] Pb,[29] Sr,[30]
and Ca.[24] The increase in TN across the series reflects
a decrease in frustration as crystal symmetry is lowered from
cubic (A = Ba) through orthorhombic (Pb), tetragonal (Sr) to
monoclinic P21/n (Ca) symmetry due to A cation size
decreasing plus Pb2+ off-centre distortion.[31] New magnetic
ground states of the MnWO6 network are stabilised in the
CaMnMnWO6 phases reported here. Ordering of cations in
the DDPv polymorph is found to switch spin order in the
MnWO6 network to ferromagnetic, with overall ferrimagnet-
ism below TC = 45 K. However, Ca/Mn disorder in the double
perovskite polymorph gives a spin glass with freezing temper-
ature Tg = 8 K. DPv-CaMnMnWO6 is notable as a highly
frustrated material featuring two types of frustrated sublat-
tices, the randomly disordered Ca/Mn cations at the A-sites
and the geometrically frustrated rocksalt Mn/W arrangement
at the B-sites. The presence of large S = 5/2 Mn2+ spins leads
to a spin glass ground state for CaMnMnWO6, but analogous
for the small saturated moment in the magnetisation meas-
urements. The refined average Mn2+ sublattice moment of
3.9(2) mB at 1.5 K is reduced from the ideal value of 5 mB
reflecting the moderate frustration. In contrast, no magnetic
diffraction peaks are observed for DPv-CaMnMnWO6 at
1.5 K (Figure S5b), showing that the Tg = 8 K peak is a spin
glass transition rather than the onset of long range magnetic
ordering. Further susceptibility measurements show that the
peak broadens and shifts to lower temperature with increas-
ing field and also shifts to slightly higher temperature with
increasing frequency in AC measurements (Figure S8), both
signatures of spin glass behaviour.
Magnetic susceptibilities for SmMnMnTaO6 in Figure 4b
show that both DDPv and DPv polymorphs have ferrimag-
netic transitions at TC = 69 and 35 K respectively. An addi-
tional transition observed at 18 K for the DDPv phase is likely
due to ordering of the Sm3+ moments with possible reor-
ientation of Mn2+ spins, as similar transitions were observed
for RMnMnSbO6 analogues based on magnetic R3+ cations.[9]
The inverse susceptibility plots show that the two polymorphs
have significantly different slopes and Curie–Weiss fits give
effective paramagnetic moments of 9.41(2) and 8.93(2) mB for
DDPv and DPv polymorphs. Subtraction of the theoretical
Mn2+ contribution gives respective estimates of 4.3 and 3.1 mB
for the Sm3+ moment, reflecting sensitivity to local environ-
ment which affects the contribution of low-energy higher J-
disordered double perovskites based on S = 1= cations like
2
Cu2+ could have quantum spin liquid ground states providing
an exciting possibility for future research. For SmMnMnTaO6
the difference between Sm/Mn order and disorder is less
dramatic as both cations are magnetic, and both DDPv and
4
www.angewandte.org
ꢁ 2021 Wiley-VCH GmbH
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
These are not the final page numbers!

Angewandte
Communications
Chemie
[7] S. Vasala, M. Karppinen, Prog. Solid State Chem. 2015, 43, 1 – 36.
[8] K.-I. Kobayashi, T. Kimura, H. Sawada, K. Terakura, Y. Tokura,
Nature 1998, 395, 677 – 680.
[9] D. Serrate, J. De Teresa, M. Ibarra, J. Phys.: Condens. Matter
2006, 19, 023201.
DPv polymorphs appear to have ferromagnetic ground states
although with greater frustration and suppression of a sepa-
rate Sm3+ magnetic transition in the latter.
In conclusion, thermal transformations under pressure of
two representative manganese-based P42/n-type AA’BB’O6
double double perovskites to (A0.5A’0.5)2BB’O6 double per-
ovskites are demonstrated. The transition is first order due to
incompatible octahedral tilts in the two structures and
proceeds entirely via coexistence of the DDPv and DPv
structures for both CaMnMnWO6 and SmMnMnTaO6. The
change from A/A’ order to disorder leads to a dramatic switch
of magnetic properties in CaMnMnWO6, from ferrimagnetic
order in the double double perovskite to a spin glass ground
state in the highly frustrated double perovskite. The ability to
generate both double double and double perovskite poly-
morphs of the same composition provides a systematic
method for exploring how frustration of long range magnetic
order can lead to spin glass or liquid ground states, and will
enable the effects of cation order and disorder on other
physical properties such as ferroelectricity and conductivity to
be explored for other materials.
[10] S. Garcꢂa-Martꢂn, E. Urones-Garrote, M. C. Knapp, G. King,
P. M. Woodward, J. Am. Chem. Soc. 2008, 130, 15028 – 15037.
[11] R. Shankar P N, F. Orlandi, P. Manuel, W. Zhang, P. S. Halasya-
mani, A. Sundaresan, Chem. Mater. 2020, 32, 5641 – 5649.
[12] E. Solana-Madruga, ꢃ. M. Arꢁvalo-Lꢄpez, A. J. Dos Santos-
Garcꢂa, E. Urones-Garrote, D. ꢃvila-Brande, R. Sꢅez-Puche,
J. P. Attfield, Angew. Chem. Int. Ed. 2016, 55, 9340 – 9344;
Angew. Chem. 2016, 128, 9486 – 9490.
[13] E. Solana-Madruga, ꢃ. M. Arꢁvalo-Lꢄpez, A. J. Dos Santos-
Garcꢂa, C. Ritter, C. Cascales, R. Sꢅez-Puche, J. P. Attfield, Phys.
Rev. B 2018, 97, 134408.
[14] G. M. McNally, ꢃ. M. Arꢁvalo-Lꢄpez, P. Kearins, F. Orlandi, P.
Manuel, J. P. Attfield, Chem. Mater. 2017, 29, 8870 – 8874.
[15] G. M. McNally, A. M. Arꢁvalo-Lꢄpez, F. Guillou, P. Manuel, J. P.
Attfield, Phys. Rev. Mater. 2020, 4, 064408.
[16] E. Solana-Madruga, Y. Sun, ꢃ. M. Arꢁvalo-Lꢄpez, J. P. Attfield,
Chem. Commun. 2019, 55, 2605 – 2608.
[17] P. Kearins, E. Solana-Madruga, K. Ji, C. Ritter, J. P. Attfield, J.
Phys. Chem. C 2021, 125, 9550 – 9555.
[18] E. Solana-Madruga, P. S. Kearins, K. N. Alharbi, C. T. Lennon,
C. Ritter, J. P. Attfield, Phys. Rev. Mater. 2021, 5, 054412.
[19] F. Millange, V. Caignaert, B. Domenges, B. Raveau, E. Suard,
Chem. Mater. 1998, 10, 1974 – 1983.
Acknowledgements
[20] Y. Hosaka, N. Ichikawa, T. Saito, P. Manuel, D. Khalyavin, J. P.
Attfield, Y. Shimakawa, J. Am. Chem. Soc. 2015, 137, 7468 –
7473.
[21] Y. Hosaka, N. Ichikawa, T. Saito, J. P. Attfield, Y. Shimakawa,
Phys. Rev. B 2016, 94, 104429.
We acknowledge EPSRC for financial support and STFC for
the provision of the beamtime at the Institut Laue-Langevin.
K.N.A. acknowledges funding from King Abdulaziz City for
Science and Technology (KACST).
[22] J. Rodrꢂguez-Carvajal, Program included FullProf Suite, version
July-2010, ILL 2010.
[23] J. Rodrꢂguez-Carvajal, Physica B: Condensed Matter 1993, 192,
55 – 69.
Conflict of Interest
[24] A. Azad, S. Ivanov, S.-G. Eriksson, J. Eriksen, H. Rundlçf, R.
Mathieu, P. Svedlindh, Mater. Res. Bull. 2001, 36, 2485 – 2496.
[25] A. M. Glazer, Acta Crystallogr. Sect. B 1972, 28, 3384 – 3392.
[26] M. S. Senn, J. P. Wright, J. Cumby, J. P. Attfield, Phys. Rev. B
2015, 92, 024104.
[27] R. D. Shannon, Acta Crystallogr. Sect. A 1976, 32, 751 – 767.
[28] A. Azad, S. Ivanov, S.-G. Eriksson, J. Eriksen, H. Rundlçf, R.
Mathieu, P. Svedlindh, Mater. Res. Bull. 2001, 36, 2215 – 2228.
[29] S. A. Ivanov, A. A. Bush, A. I. Stash, K. E. Kamentsev, V. Y.
Shkuratov, Y. O. Kvashnin, C. Autieri, I. Di Marco, B. Sanyal, O.
Eriksson, Inorg. Chem. 2016, 55, 2791 – 2805.
The authors declare no conflict of interest.
Keywords: double perovskites · high-pressure chemistry ·
magnetic properties · solid-state structures
[1] R. J. Tilley, Perovskites: structure-property relationships, Wiley,
Hoboken, 2016.
[2] C. J. Howard, H. T. Stokes, Acta Crystallogr. Sect. B 1998, 54,
782 – 789.
[3] C. J. Howard, B. J. Kennedy, P. M. Woodward, Acta Crystallogr.
Sect. B 2003, 59, 463 – 471.
[4] M. T. Anderson, K. B. Greenwood, G. A. Taylor, K. R. Poep-
pelmeier, Prog. Solid State Chem. 1993, 22, 197 – 233.
[5] G. King, P. M. Woodward, J. Mater. Chem. 2010, 20, 5785 – 5796.
[6] A. Aimi, D. Mori, K.-i. Hiraki, T. Takahashi, Y. J. Shan, Y.
Shirako, J. Zhou, Y. Inaguma, Chem. Mater. 2014, 26, 2601 –
2608.
[30] A. Azad, S. Ivanov, S.-G. Eriksson, H. Rundlçf, J. Eriksen, R.
Mathieu, P. Svedlindh, J. Magn. Magn. Mater. 2001, 237, 124 –
134.
[31] J.-W. G. Bos, J. P. Attfield, Phys. Rev. B 2004, 70, 174434.
Manuscript received: June 28, 2021
Accepted manuscript online: August 8, 2021
Version of record online: && &&, &&&&
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
ꢁ 2021 Wiley-VCH GmbH
www.angewandte.org
5
These are not the final page numbers!

Angewandte
Communications
Chemie
Communications
Perovskites
Thermal transformations under pressure
of AA’BB’O6 double double perovskites,
where both A and B sites have 1:1 cation
order, to (A0.5A’0.5)2BB’O6 double per-
ovskites with disordered A/A’ cations are
demonstrated for CaMnMnWO6 and
SmMnMnTaO6, leading to a dramatic
switch in magnetic properties from ferri-
magnetic order to spin glass behaviour in
the former.
K. Ji, K. N. Alharbi, E. Solana-Madruga,
G. T. Moyo, C. Ritter,
J. P. Attfield*
&&&& — &&&&
Double Double to Double Perovskite
Transformations in Quaternary
Manganese Oxides
6
www.angewandte.org
ꢁ 2021 Wiley-VCH GmbH
Angew. Chem. Int. Ed. 2021, 60, 1 – 6
These are not the final page numbers!