Dielectric Properties of Tungsten Bronze BaO-Nd_2O_3-Bi_2O_3-TiO_2 and Effect of ZrO_2 Substitution

摘要

The dielectric properties of (6-3x) BaO-(4+x) (Nd_(1-y)Bi_2)_2O_3-18TiO_2 (0.4 <= x <= 0.9, 0 <= y <=0.2) were investigated in the microwave region. The range of the tungsten bronze single phase was determined. The temperature coefficient of resonant frequency (#tau#_f) decreases with an increase in the "x" and that tungsten bronze Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54) single phase forms in the range of 0.4 <= x <= 0.775. #tau#_f increases with an increase in the "x" in the range of 0.8 <= x <=0.9, which is attributed to the formation of Nd_4Ti_9O_(24). Dielectric properties of Zr-substituted Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54) were investigated. An increase in the radius of Ti site results in the increase of #tau#_f. It was attempted to establish the relationship between #tau#_f and average ionic radius of Ba-R site, Ba~(2+), Nd~(3+) and Bi~(3+). #tau#_f decreases with a decrease in the average ionic radius. however, #tau#_f does not depend only on the average radius of Ba~(2+), Nd~(3+) and Bi~(3+).