Does BaTbO3 Adopt the P1 Symmetry?: Does BaTbO3 Adopt the P1 Symmetry?

A detailed profile analysis of X-ray diffraction data in the temperature range between 100 K and 723 K was carried out to settle a recent dispute on the symmetry and crystal structures of the perovskite BaTbO3. Through careful comparison of the Rietveld refinements, we found that there is no evidence to suggest a triclinic (P1) structure for BaTbO3. The correct space groups with decreasing temperature are I4/mcm and Imma, respectively. At around room temperature both structures co-exist. The phase sequence of "Pm3m" -> I4/mcm -> Imma is just the one expected to occur in A(II)B(IV)O-3-type perovskites.