Gd2Zr3(MoO4)9 microwave dielectric ceramics with trigonal structure for LTCC application

Gd2Zr3(MoO4)(9) is a double trigonal molybdate crystallized in the space group R3 over bar c. The optimal microwave dielectric properties were achieved via solid-state reaction at 725 degrees C for Gd2Zr3(MoO4)(9) ceramics: epsilon(r) = 11.17, Q x f = 57 460 GHz, tau(f) = -31.91 ppm/degrees C. The three-dimensional framework type structure is formed by mixed MoO4 tetrahedron and ZrO6/GdO9 polyhedron. The analysis based on complex chemical bond theory shows that the Mo-O bonds account for majority contribution to controlling microwave dielectric properties. The MoO4 tetrahedron and ZrO6 octahedron stabilize the crystal structure by strong binding ability. As it was shown by Raman spectroscopy, the Raman-active vibrations primarily originate from MoO4 tetrahedron, similarly to molybdate analogies.