The Research Of Ba-Ti-Nd System And Effect Of Bi₂O₃ Dopant

Because of good dielectric properties of BaO-Nd2O3-TiO2 system, it becomes one of the most widely studied microwave dielectric ceramics. The main crystal phase formula is Ba6-3xNd8+2xTi18O54. This kind of dielectric material has the advantages of high dielectric constant, low dielectric loss, and becoming one of the widely used materials in microwave communication devices.The material of Ba6-3xNd8+2xTi18O54 when x=5/12 was studied in this paper. Firstly, the relations of Ba19/4Nd53/6Ti18O54's dielectric properties with calcining temperature and sintering temperature were studied. It is found that appropriate calcining temperature is good for the formation of the main crystal phase and the improvement of dielectric property in this system. The main crystal phase will not grow completely when calcining temperature is too low and it will grow unconventionally when calcining temperature is too high, both of them are not good for the improvement of the material. Higher sintering temperature can make the material denser and the main crystal phase can grow completely, and will benefit for the improvement of the material's dielectric property.The dielectric properties of the materials were studied when changing the stoichiometric ratio of Ba2+ in the system. The adjustment of the amount of Ba2+ can change the crystal phase of tungsten bronze in rich TiO2 region and affect the dielectric properties of the materials, dielectric constant becomes lower, dielectric loss becomes higher, and the absolute value of temperature coefficient becomes larger when increasing the amount of Ba2+.It's studied that the improvement of the dielectric properties by adding Bi3+, substituting Bi3+ for Nd3+, adding Bi3+ and substituting Bi3+ for Nd3+ simultaneously in the ceramic. The results show that all the three methods can increase dielectric constant and dielectric loss, and shift the temperature coefficient for zero in general. The increase of sintering temperature can also benefit for the dielectric properties of the materials prepared through the three methods, the dielectric constant may increase, but much too high sintering temperature may take the opposite effect. Dielectric loss increases slightly, the absolute value of temperature coefficient may decrease when increasing sintering temperature.