New double perovskites having low dielectric loss: LaBaZnTaO6, LaSrZnNbO6,and Ba2Zn0.5Ti0.5TaO6

Oxides of the type LaBaZnTaO6 and LaSrZnNbO6 have been synthesized by the s olid-state method at 1100 degreesC. Ba2Zn0.5Ti0.5TaO6 was synthesized by th e molten salt method (using NaCl-KCl as flux), the solid-state method yield ing a biphasic mixture of BaTiO3 and BaZn1/3Ta2/3O3. LaBaZnTaO6 and LaSrZnN bO6 were found to crystallize in an ordered (cubic) double perovskite struc ture in the Fm (3) over barm space group with a = 8.0867(8) and 8.001(1) An gstrom, respectively. Ba2Zn0.5Ti0.5TaO6 crystallizes in the disordered cubi c perovskite structure with a = 4.054(1) Angstrom. These oxides have very l ow dielectric losses in the region of 0.0005 to 0.003 (500 kHz). The dielec tric constants of LaBaZnTaO6 and LaSrZnNbO6 are low (13 and 10, respectivel y) while Ba2Zn0.5Ti0.5TaO6 has a high dielectric constant of 36 at 500 kHz. (C) 2001 Elsevier Science Ltd. All rights reserved.