THE NON-STOICHIOMETRIC PEROVSKITE BAPBO3-x: CRYSTAL STRUCTURE AND CATION - ANION DISTRIBUTION
September 4-8, 2016
The ABO3 perovskites reveal a large structural tolerance for enabling a variety of substitutions at both A and B sites and for a wide range of cation and vacancy ordering. This led to a number of discoveries of useful chemical and physical properties.
In particular the oxygen deficit influences the electrical conductivity of ABO3 perovskites. The degree of oxygen deficiency is influenced by sample preparation, calcination temperature and atmosphere used for synthesizing and annealing. However, oxygen measurements are challenging and the references give either none or incorrect data. Finally, conclusions described in literature about the structure of BaPbO3 are contradicting with respect to the oxygen content.
Describing the structure, the most suggested space groups in references for BaPbO3-x are either the monoclinic space group I2/m [1-3] or the orthorhombic space group Imma [4, 5]. Imma as well as I112/m show tilted PbO6 octahedra around the  - and  - axis of the cubic aristotype. Although the tilt angle for Imma equals for a- and b-axis, it is different in I112/m. If differences between tilt angles are small a structural classification is rather difficult.
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Alexandra Franz and Michael Tovar, "THE NON-STOICHIOMETRIC PEROVSKITE BAPBO3-x: CRYSTAL STRUCTURE AND CATION - ANION DISTRIBUTION" in "Nonstoichiometric Compounds VI", ECI Symposium Series, (2016). https://dc.engconfintl.org/nonstoichiometric_vi/43