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

CaNd2CuTi2O9 · Pbnm · 300 K

CaNd2CuTi2O9 · Pbnm · 300 K

status published · visibility public · id str:cand2cuti2o9.pbnm.300k.iturbe2012

Material
CaNd2CuTi2O9
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)
5.4557(1) 5.5769(1) 7.6594(2) 90 90 90

Atoms

label element Wyckoff x y z occ. Biso (Ų)
Ca/Nd Ca 4c -0.0079(6) -0.0467(4) 0.75 0.35/0.65 0.70(6)
Cu/Ti Cu 4b 0.5 0 0 0.35/0.65 0.5 (fixed)
O1 O 4c 0.423(3) 0.020(3) 0.75 1 1.5(3)
O2 O 8d 0.202(2) 0.790(2) 0.458(2) 1 1.5(3)

Structure for calculations

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

# Perovskite Atlas · str:cand2cuti2o9.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
5.4557 5.5769 7.6594 90 90 90
4
Ca 1 4c -0.0079 -0.0467 0.75   # Ca/Nd, occupancy 0.35/0.65
Cu 1 4b 0.5 0 0   # Cu/Ti, occupancy 0.35/0.65
O 1 4c 0.423 0.020 0.75   # O1
O 2 8d 0.202 0.790 0.458   # O2
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Refinement

software method variant Rp Rwp Rexp RBragg χ² parameters
FullProf symmetry-mode all-modes 2.12

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 1.26(1) primary antiphase octahedral tilt
R5+ (1/2,1/2,1/2) 2 Imma 0.04(1) octahedral deformation
X5+ (0,1/2,0) 2 Cmcm 0.21(1) A-site antipolar displacement
M2+ (1/2,1/2,0) 1 P4/mbm 0.01(1) octahedral deformation
M3+ (1/2,1/2,0) 1 P4/mbm 0.96(1) primary in-phase octahedral tilt

Geometry (as reported)

fer document ↗ standardised version of this record

Bond angles

angle value (°)
a/Ln-O1(×1)(Å) 3.20(2)
a/Ln_-O2(×2)(Å) 2.67(1)
a/Ln-O2(×2)(Å) 3.37(1)
a/Ln-O>8short^a(Å) 2.52(2)
u/Ti-O1_ax(×2)(Å) 1.97(1)
u/Ti-O2_eq(×2)(Å) 1.99(1)
u/Ti-O2^′_eq(×2)(Å) 2.03(1)
u/Ti-O>(Å) 1.99(1)
O1_ax-Cu/Ti-O2_eq(^°) 89.2(3)
O1_ax-Cu/Ti-O2′_eq(°) 90.4(2)
O2_eq-Cu/Ti-O2′_eq(°) 90.0(2)
Cu/Ti-O1_ax-Cu/Ti(^°) 154.1(5)
Cu/Ti-O2_eq-Cu/Ti(^°) 152.4(3)

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

Evidence