Li₂O-Nb₂O₅-TiO₂ Microwave Dielectric Ceramics And Low Temperature Co-fired Research

system behaves excellent microwave dielectric properties, but it is difficult for a series of performance: zero temperature frequency coefficient, dielectric properties and Qf Value to meet multiformity of materials synchronously. Moreover, at present the researches on Li2O-Nb2O5-TiO2 system focused on high temperature(1100 ) and it is difficult to realize LTCC (low temperatrure co-fired ceramic) of microwave dielectric ceramics. It is essential to investigate its characteristics at low temperature (near to 900 ). With the general review of microwave dielectric ceramics and the researches of the authors on microwave ceramic chips, the microstruture of Li2O-Nb2O5-TiOa system powders calcined at 900 , the effects of addtives on the properties of the system and the low-temprature-sintering of the system were investigated.The microstructures and properties of Li2O-Nb2O5-TiO2 powder calcined at low temperature (900 ) were investigated. With the increase of titanium oxide (TiO2) content, there existed LiNbO3 solid solution containing Ti4+, M-Phase and rutile typed TiO2- When the content of TiO2 was more than 43.7mol%,there existed Li2TiO3 ;When the content of TiO2 varied from 34.1mol% to 43.7mol%,Li2TiO3 disappeared if caicined at 900 which was in existence at lower temperature .With the increase of titanium oxide (TiO2) content, the lattices a (or c) of M-Phase elongated (or shrinked), just in reverse with the phenomenon at high temperature (1100 ).The powers calcined 880 ~950 was found that no impurity peeks in appearance.The effects of Zinc oxide (ZnO) and Bismuth oxide (Bi2O3) on the microwave dielectric properties of Li2O-Nb2O5-TiO2 system were investigated. Zn2TiO4 and Bi4Ti3O12 were found but had inapparent influence on M-Phase,and the latter favored to lower sintering temperature. When Bi2O3/ZnO=2/l (wt),liquid which turned ultimately to Zn2TiO4 and Bi4Ti3O12 ,was found and lowerd sintering temperature to 970 .Small amount of Bi2O3 did no good of Qf Value,heightened the dielectricconstant and the temperature coefficient of frequency;ZnO lowered the temperature frequency coefficient notability and lowed the dielectric constant in some sort.It was capable to achieve feasible dielectric constant via introduce of impurities and meet demand.The effects of both Zinc oxide (ZnO) and Boron oxide (B203) on the microwave dielectric properties of Li2O-Nb2O5-TiO2 system at low temperature were investigated. Boron oxide(B2O3)(2.5wt%) lowerd the sintering temperature to 850 , increased temperature frequency coefficient , decreased dielectric constant, but did nothing to Qf Value on the whole .Zinc oxide dissolves in Boron oxide and reacted with titanium oxide(TiO2) to form Zn2TiO4. With the increase of content of ZnO,the temperature coefficient of frequency reduced to negative , dielectric constant minished and did disadvantage to Qf Value. With the fluctuating of temperature,or of the content of Zinc oxide (ZnO) and Boron oxide (8203), frequency coefficient and dielectric constant was feasible. Microwave dielectric ceramics with performance æ‹¢ r =63, Qf=3200 GHz, f =+0.6 ppm/ was obtained, which was sinered at 900 with 4wt% Zinc oxide and 0.5wt% Boron oxide.In the last section, a chip sintered at 900 with the aidditive of vanadium oxide(V2O5) was exhibited.