Chemical bonding characteristics and dielectric properties of Nd2(Ba1−xSrx)ZnO5 solid solutions

Abstract

The relationship between the microwave dielectric property and crystal structure of Nd2(Ba1−xSrx)ZnO5 solid solutions was investigated using bond valence theorem and first principle method (DV-Xα method). The evaluation of the covalence characteristics of cation–oxygen bonds revealed that as the x value increased, the covalence characteristics of the M–O (M = Ba and Sr) bonds in the MO10 polyhedron decreased while those of the Zn–O(2) bonds in the ZnO4 tetrahedron increased. From the DV-Xα method, it was found that the 3d electrons of the Zn2+ ion are closely related to the strong covalence characteristics of the Zn–O(2) bonds. The dielectric constants were approximately constant over the whole composition; this result is considered to relate to the decrease in the covalence characteristic of the M–O bonds. The quality factors increased from 4915 to 25,836 GHz, and the grain growth of the solid solutions are considered to improve the Q × f values.