On the symmetry and crystal structures of Ba2LaIrO6

Accurate profile analysis of X-ray diffraction data was carried out to settle recent dispute on the symmetry and crystal structures of the double perovskite Ba2LaIrO6. Even through careful comparison of the full-width at half-maximum values, we found no evidence for Ba2LaIrO6 adopting either monoclinic (I 2/m ) or mixed rhombohedral View the MathML source(R3¯) and monoclinic (I 2/m ) structures at room temperature, becoming triclinic View the MathML source(I1¯) at below about 200 K. The correct space group is just View the MathML sourceR3¯ at temperatures between 82 and 653 K. Furthermore, the View the MathML sourceR3¯→Fm3¯m phase transition does occur in Ba2LaIrO6, but the transition temperature is found to be much higher than the reported value.