Study On The Dielectric Properties Of Ba-Ti-Nd Ceramic Materials System

The dielectric properties of Ba_6-3xNd_8+2xTi₁₈O₅₄ ceramic materials were studied systematically in this dissertation. The results shown that dielectric constant and loss of the system decreased as x increased before x=2/3. When x=2/3 dielectric constant of the system increased obviously, after this ratio dielectric constant of the system decreased as x increased. When x=1/2, the ceramic material had ideal dielectric properties. At this ratio,εof the ceramic materials was approximately 80; tgδ<1×10-4;αεwas -150×10-6/℃.On the basis of the study of Ba_6-3xNd_8+2xTi₁₈O₅₄ ceramic materials, La³⁺,Sr²⁺,Ca²⁺and Bi2O3 were doped into BaNd2Ti4O12. The results shown that in BaNd2-xLaxTi4O12 ceramic materials dielectric constant became higher; temperature coefficient moved to negative direction; dielectric loss was smaller as x increased. Sr element and Ca element both belong to IIA main group, but they had different effects when it doped into BaNd₂Ti₄O₁₂ ceramic materials. In Ba_1-xSr_xNd₂Ti₄O₁₂ system, dielectric constant became smaller first then higher and smaller at last. When x varied from 0.2 to 0.25, dielectric constant has the highest value. When x was near to 0.15, dielectric loss is very high. When x was near to 0.2, temperature coefficient was nearest to zero, then the absolute value of temperature coefficient became higher as x increased. In Ba_1-xCa_xNd₂Ti₄O₁₂ system, dielectric constant became higher gradually as x increased, but when x was 0.3, dielectric constant became very low. Dielectric loss of the system was obviously higher as x increased, temperature coefficients are minus, and moved to negative direction then moved to positive direction as x increased. Bi₂O₃ was doped into Ba_0.95Ca_0.05Nd₂Ti₄O₁₂ ceramic materials. When Bi2O3 is 4wt%, the system had the best dielectric properties. Temperature coefficient moved to positive direction as x increased.On the basis of this study, a kind of high frequency temperature stable ceramic material can be developed which may have proper dielectric constant, low loss and low absolute value of temperature coefficient.