Li过量对M-相固溶体Li_2O-Nb_2O_5-TiO_2陶瓷微波介电性能的影响

含有M-相固溶体Li2O-Nb2O5-TiO2(LNT)的微波介质陶瓷具有烧结温度(约1100℃)低,介电常数εr(65～70)及Q·f值(约5000 GHz)高的特点,但其频率温度系数τ却往往偏高(约23×10–6/℃)。为此,系统研究了非化学计量比下Li含量对LNT陶瓷微波介电性能的影响。实验结果表明,Li含量增加能有效调节LNT陶瓷的频率温度系数至近零而不影响其他性能。当Li含量过量5%(质量分数)时,LNT陶瓷具有最佳性能:εr=69.73,Q·f=5 543GHz(=3.518 GHz),τf=–4.4×10–6/℃。

Effects of lithium excess on the microwave dielectric properties of Li2O-Nb2O5-TiO2 microwave dielectric ceramics

The microwave dielectric ceramics made with the M-phase solid solution Li2O-Nb2O5-TiO2(LNT) possess low-sintering temperature(about 1100 ℃),high permittivity εr(65-70) and high Q·f values(about 5000 GHz).However,the temperature coefficient of frequency,τf,of the LNT ceramics was always too high(about 23×10–6/℃)for practical application.The effects of nonstoichiometric Li content on the microstructure and microwave dielectric properties of the LNT ceramics were hence studied.The results show that addition of excessive Li can effectively reduce the τf value of the LNT ceramics to almost zero with no significant degradation in other properties.When 5 more weight percent of Li is added,the LNT ceramic shows the best performances: εr=69.73,Q·f=5 543 GHz(f=3.518 GHz),τf= –4.4×10–6/℃.