Hydrothermal synthesis and crystal structure of Li,Ba-nanoborate, LiBaB9O15 and Ba-borophosphate, BaBPO5

The crystal structure determination of lithium and barium nanoborates synthesized under hydrothermal conditions was reported. The structure of BaBPO5 was refined by Rietveld method in contrast to the structure of PbBAsO5, which was determined on a single crystal. The phase transformation at high temperature in the stillwellite structure type accompanied by the replacement of the polar space group was also reported. The phase expansion of the La-polyhedron was compared to BO4 and GeO4 tetrahedra