Jianhua Zhu,Qian Xiao,Ting Zhang,Yefeng Yin,Yang Liu
The effects of acceptor dopant (typical Mn 2+ ) and donor dopant (typical V 5+ ) on the reliability of Li 2 ZnTi 3 O 8 based low temperature co-fired ceramics (LTCC, in short) have been investigated. Large difference occurs among different types of dopants. V 5+ doping decreases the breakdown voltage of the multilayer capacitors which were manufactured by low temperature sintered Li 2 ZnTi 3 O 8 ceramics, however, Mn 2+ doping increases the breakdown voltage and lowers down the leakage current significantly. This may very likely due to the fact that donor induces the generation of weak bound electrons while acceptor capture the weak bound electrons. The results suggest that Mn 2+ is a very effective additive for improving the reliability of low temperature sintered Li 2 ZnTi 3 O 8 ceramics.
Zhifen Fu,Chang Li,Chen Chen,Yubin She,Zhongyi Yang
low-fired Li2ZnTi3O8 ceramics were fabricated by a solid-state reaction method for developing LTCC applications. TLBBC mixed sintering aid was used to improve the sintering stability. X-ray diffraction analyses demonstrated that specimens corresponded well to the cubic crystal symmetry structure of Li2ZnTi3O8, accompanying with a little of impure phase Ca3Ti2O7 and LiBO2. The sintering temperatures of Li2ZnTi3O8 ceramics were lowered to 950 °C due to the formation of low melting point LiBO2. At x = 3, Li2ZnTi3O8 ceramics exhibited an microwave dielectric properties with εr = 21.0, tanδ = 5.76 × 10−4, Q × f = 14750 GHz, τf = −11.5 ppm/°C at 950 °C.
Kui Liu,Liang Shi,Xueying Wang,Cheng Liu,Jie Li,Yulong Liao,Lichuan Jin,Dainan Zhang,Huaiwu Zhang
Herein, Li + -enriched Li (1+ x )2 ZnTi 3 O 8 ceramics are prepared via the solid-phase methods. As x increases, the unit cell volume gradually increases, while the grain size initially increases and then decreases gradually. The Li (1+0.06)2 ZnTi 3 O 8 ceramics exhibit the best dielectric properties : ε r = 25.92, Q × f = 109534 GHz (@7.37 GHz, which is a 48 % increase compared with the stoichiometric counterpart.), and τ f = −8.21 ppm/°C. The complex chemical bond theory and Raman spectroscopy reveal that Ti-O bonds have a significant effect on the dielectric properties . An optimal Li + enrichment leads to an overall reduction in the distortion of the Li/ZnO 4 tetrahedra, resulting in a reduction in τ f . First-principles calculations demonstrate that a suitable excess of Li + leads to an increase in the band-gap as well as an enhanced electron cloud density in the internal space of the Li1/ZnO 4 tetrahedra, thereby increasing the Q × f . In summary, Li + -enriched Li (1+0.06)2 ZnTi 3 O 8 ceramics are promising for a wide array of applications in microwave communications.
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