Chemical bonding characteristics and dielectric properties of Nd-2(Ba1-xSrx)ZnO5 solid solutions

摘要

The relationship between the microwave dielectric property and crystal structure of Nd-2(Ba1-xSrx)ZnO5 solid solutions was investigated using bond valence theorem and first principle method (DV-Xalpha 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-Xalpha 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 x f values. [References: 22]