Improvement of temperature coefficient of frequency in Ba-deficient Ba 5Nb4O15 microwave dielectrics

Abstract

Ba-deficient non-stoichiometric compositions of Ba5-xNb 4O15-x (x = 0 to 0.5) have been investigated for the purpose of improving microwave dielectric properties. While there was no significant variation in dielectric constant, variations in Q × f and TCF (temperature coefficient of frequency) values with the degree of Ba deficiency were prominent. Near zero TCF value was obtained for the composition of Ba 4.77Nb4O14.77. The apparent formation of a second BaNb2O6 phase for the Ba-deficient compositions was believed as responsible for the improved TCF. It was interesting to note that the second phase was present more preferably inside of the sample.