perovskite atlas Structures, modes and phase transitions · Josu M. Igartua · UPV/EHU

CaSm2CuTi2O9 · Pbnm · 300 K

CaSm2CuTi2O9 · Pbnm · 300 K

status published · visibility public · id str:casm2cuti2o9.pbnm.300k.iturbe2012

Material
CaSm2CuTi2O9
Space group
Pbnm · No. 62
Setting
Pbnm (non-standard setting of Pnma, No. 62)
Phase
room temperature
Temperature
300 K

fer document ↗ standardised version of this record

Cell

a (Å) b (Å) c (Å) α (°) β (°) γ (°) V (ų)
5.4221(2) 5.6097(2) 7.6129(3) 90 90 90

Atoms

label element Wyckoff x y z occ. Biso (Ų)
Ca/Sm Ca 4c -0.0109(6) -0.0558(4) 0.75 0.35/0.65 0.84(7)
Cu/Ti Cu 4b 0.5 0 0 0.35/0.65 0.5 (fixed)
O1 O 4c 0.406(4) 0.033(3) 0.75 1 1.5(3)
O2 O 8d 0.197(3) 0.797(3) 0.456(2) 1 1.5(3)

Structure for calculations

CIF: absent. Bilbao Crystallographic Server input (AMPLIMODES, SYMMODES, PSEUDO), uncertainties stripped:

# Perovskite Atlas · str:casm2cuti2o9.pbnm.300k.iturbe2012
# Space group Pbnm (No. 62) · setting: Pbnm (non-standard setting of Pnma, No. 62)
# BCS structure format: space-group number / cell / number of atoms / element index Wyckoff x y z
62
5.4221 5.6097 7.6129 90 90 90
4
Ca 1 4c -0.0109 -0.0558 0.75   # Ca/Sm, occupancy 0.35/0.65
Cu 1 4b 0.5 0 0   # Cu/Ti, occupancy 0.35/0.65
O 1 4c 0.406 0.033 0.75   # O1
O 2 8d 0.197 0.797 0.456   # O2
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Refinement

software method variant Rp Rwp Rexp RBragg χ² parameters
FullProf symmetry-mode all-modes 2.43

Symmetry-mode decomposition

fer document ↗ standardised version of this record

Parent
Pm3m
Software
AMPLIMODES
Convention
amplimodes-cell
Variant
all-modes
irrep k direction dim isotropy subgroup amplitude (Å) role physical meaning
R4+ (1/2,1/2,1/2) 1 Imma 1.40(4) primary antiphase octahedral tilt
R5+ (1/2,1/2,1/2) 2 Imma -0.04(4) octahedral deformation
X5+ (0,1/2,0) 2 Cmcm 0.36(3) A-site antipolar displacement
M2+ (1/2,1/2,0) 1 P4/mbm 0.07(4) octahedral deformation
M3+ (1/2,1/2,0) 1 P4/mbm 1.09(4) primary in-phase octahedral tilt

Geometry (as reported)

fer document ↗ standardised version of this record

Bond angles

angle value (°)
a/Ln-O1(×1)(Å) 3.35(2)
a/Ln_-O2(×2)(Å) 2.64(1)
a/Ln-O2(×2)(Å) 3.44(1)
a/Ln-O>8short^a(Å) 2.49(2)
u/Ti-O1_ax(×2)(Å) 1.98(1)
u/Ti-O2_eq(×2)(Å) 2.01(1)
u/Ti-O2^′_eq(×2)(Å) 2.03(1)
u/Ti-O>(Å) 2.01(1)
O1_ax-Cu/Ti-O2_eq(^°) 90.0(3)
O1_ax-Cu/Ti-O2′_eq(°) 93.1(2)
O2_eq-Cu/Ti-O2′_eq(°) 90.4(2)
Cu/Ti-O1_ax-Cu/Ti(^°) 147.0(5)
Cu/Ti-O2_eq-Cu/Ti(^°) 150.1(3)

Rietveld refinement of XRPD data by symmetry-mode parametrisation (AMPLIMODES for FullProf). Original files expected from data rescue.

Evidence