6H hexagonal structure of low loss Ba3MTiWO9 (M = Mg, Zn) dielectrics

The crystal structure of Ba3MTiWO9 (M = Mg, Zn) oxides has been found to be 6H hexagonal, space group P63/mmc, parameters of unit cell: a = 5.7943(1) إ, c = 14.1642(1) إ and a = 5.7993(1) إ, c = 14.1626(1) إ for M = Mg and Zn, respectively. The tungsten and titanium atoms are randomly distributed in pairs of face-sharing octahedra separated by octahedral layers containing magnesium or zinc. It was revealed that the structures are well ordered which is believed to result in a low dielectric loss at a microwave frequency reported for these materials.