The Effect of Impurity Phases on the Structure and Properties of Microwave Dielectrics Based on Complex Perovskites Ba(Co1/3 2 + Nb2/3)O3

Two major secondary phases have been revealed in the ceramics based on the complex perovskites Ba(Co 1/3 Nb 2/3 )O 3 : a Ba-rich compound Ba 8 CoNb 6 O 24 with the layered perovskite structure, and a Nb-rich compound with the structure of tetragonal tungsten bronze and the composition close to Ba 6 CoNb 9 O 30 . The presence of a small amount of the Ba-rich phase is accompanied with the rise in the quality factor (Q) of the material whereas the high amount is deleterious to Q. In contrast, the presence of even a small amount of Nb-rich phase always results in a sharp fall in the Q-factor. The ways of tuning temperature coefficient τ f in Ba(Co 1/3 Nb 2/3 )O 3 ceramics have been discussed.