Structural variants in ABO3 type perovskite oxides. On the structure of BaPbO3

The structure of BaPbO3 has been refined from powder neutron and synchrotron X-ray diffraction data at both room temperature and 15 K. At room temperature the structure is orthorhombic, space group Imma a=6.0299(1), b=8.5094(1), c=6.6094(1) Å. Rp 5.26, Rwp 6.48, χ2 2.45%. On cooling the structure transforms to a monoclinic form, space group C2/m, a=8.5548(1) b=8.4808(1) c=6.0118(1) Å β=134.806(1). Rp 5.30, Rwp 6.50, χ2 2.64%.