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

BaNd2CuTi2O9 · I4/mcm · 300 K

BaNd2CuTi2O9 · I4/mcm · 300 K

status published · visibility public · id str:band2cuti2o9.i4mcm.300k.iturbe2012

Material
BaNd2CuTi2O9
Space group
I4/mcm · No. 140
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)
5.5773(2) 5.5773(2) 7.8743(5) 90 90 90

Atoms

label element Wyckoff x y z occ. Biso (Ų)
Ba/Nd Ba 4b 0 0.5 0.25 0.35/0.65 1.5(1)
Cu/Ti Cu 4c 0 0 0 0.35/0.65 0.5 (fixed)
O1 O 4a 0 0 0.25 1 5.8(6)
O2 O 8h 0.273(6) 0.227(6) 0 1 5.8(6)

Structure for calculations

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

# Perovskite Atlas · str:band2cuti2o9.i4mcm.300k.iturbe2012
# Space group I4/mcm (No. 140)
# BCS structure format: space-group number / cell / number of atoms / element index Wyckoff x y z
140
5.5773 5.5773 7.8743 90 90 90
4
Ba 1 4b 0 0.5 0.25   # Ba/Nd, occupancy 0.35/0.65
Cu 1 4c 0 0 0   # Cu/Ti, occupancy 0.35/0.65
O 1 4a 0 0 0.25   # O1
O 2 8h 0.273 0.227 0   # O2
Copy

Refinement

software method variant Rp Rwp Rexp RBragg χ² parameters
FullProf symmetry-mode all-modes 2.08

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 I4/mcm -0.35(9) primary antiphase octahedral tilt

Geometry (as reported)

fer document ↗ standardised version of this record

Tilt angles

angle value (°)
ψ_[001]p 9.3(2)

Octahedra: bond lengths, mean and predicted (bond-valence) distances, volumes

octahedron bond length (Å) predicted (Å) V (ų)
Ba/LnO12 mean 2.794(9)

Bond lengths

bond length (Å)
Ba/Ln-O1(×4) 2.789(1)
Ba/Ln-O1(×4) #2 3.024(9)
Ba/Ln-O1(×4) #3 2.568(7)

Bond angles

angle value (°)
u/Ti-O1_ax(×2) 1.97(1)
u/Ti-O2_eq(×4) 2.00(1)
mean u/Ti-O 1.99(1)
O2_eq-Cu/Ti-O2^′_eq 90.0(2)
Cu/Ti-O2_eq-Cu/Ti 161.4(3)

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

Evidence