Crystal structure of Ba(Mg1/3Ta2/3)O3 calcinated at 1400°C

Abstract

A new phase of Ba(MgI~3Ta2/3)O 3 has been obtained by calcination at 1400 C. It belongs to the cubic Pm3m with a = 4.08840(4)/~ and the crystal structure has been found to be the ideal perovskite by the Rietveld method from powder X-ray diffraction data.

Analysis of Ba(Mg1/3, Ta2/3)O3 by atomic-resolution scanning transmission electron microscopy

“…37) The atom column displacements were calculated with reference to the crystal structure estimated by XRD. 38) Fast Fourier transform was used to orient and scale the reference structure of the STEM image. The resulting atomic positions of the reference structure were used as the origin of each atomic column.…”

Evaluation of polymorphism and charge transport in a BaO–CaO–Ta2O5 perovskite phase diagram using TOF-neutron and synchrotron X-ray diffraction, the bond-valence method and impedance spectroscopy

“…Up to now, the Inorganic Compound Structure Database (ICSD) has collected 93 Ba–M–Ta–O quaternary perovskite-type metal oxides with a general chemical formula of Ba 3 M 1+ x Ta 2− x O 9− δ . Although all M n + ions are octahedrally coordinated with O 2− ions, their ionic size and charge are the two main factors to drive them to crystallize into 7 different space groups: I 4/ m (M = Ho 3+ , Eu 3+ , Y 3+ ), 17–20 I 12/ m 1 (M = Bi 3+ , La 3+ , Ce 3+ , Lu 3+ ), 18,21–23 P 12 1 / n 1 (M = La 3+ ), 18,24 R̄ 3 (M = La 3+ , Bi 3+ ), 18,21,25 P 6 3 / mmc (M = Sr 2+ , Li + , Cr 3+ ), 26–28 Fm̄ 3 m (M = Yb 3+ , Bi 3+ , Ho 3+ , Y 3+ , Ca 2+ , In 3+ , Lu 3+ ), 17,18,24,25,29–32 Pm̄ 3 m (M = Mg 2+ , Co 2+ , Fe 2+ , Mn 2+ , Y 3+ , Sc 3+ , Yb 3+ , Ca 2+ ), 33–37 and P̄ 3 m 1 (M = Mg 2+ , Zn 2+ , Ca 2+ , Ni 2+ , Sr 2+ ). 30,34,38–44 Among the above groups, lanthanum ions or cations with 3+ charge often have a tendency to crystallize into open structures to reduce the electrostatic interaction, and they include I 4/ m , I 12/ m 1, P 12 1 / n 1, R̄ 3, and P 6 3 / mmc .…”