Preparation, phase structure and microwave dielectric properties of CoLi2/3Ti4/3O4 ceramic

Graphical abstract: For chemical compatibility tests with silver electrode, mixtures of ceramic powders with 20 wt% Ag powders were cofired and analyzed to detect interactions between the low-fired samples and electrodes. XRD patterns and backscattered electron image of CoLi{sub 2/3}Ti{sub 4/3}O{sub 4} ceramics added with 1.5 wt% BCB cofired with Ag at 900 Degree-Sign C for 2 h are presented in . Backscattered electron image analysis reveals no interaction to form new phases after firing. This observation is also confirmed by the evidence of no difference between the XRD patterns before and after firing. It is obvious that the reaction of low-fired CoLi{sub 2/3}Ti{sub 4/3}O{sub 4} ceramics with Ag electrodes did not occur. Highlights: Black-Right-Pointing-Pointer A new microwave dielectric ceramic with good properties was reported. Black-Right-Pointing-Pointer The addition of BaCu(B{sub 2}O{sub 5}) can lower the sintering temperature from 1050 Degree-Sign C to 900 Degree-Sign C. Black-Right-Pointing-Pointer The addition of BaCu(B{sub 2}O{sub 5}) does not induce degradation of properties. Black-Right-Pointing-Pointer BCB added CoLi{sub 2/3}Ti{sub 4/3}O{sub 4} ceramics can co-fire with Ag electrode. -- Abstract: A new low loss microwave dielectric ceramic with composition of CoLi{sub 2/3}Ti{sub 4/3}O{sub 4} was prepared by a conventional solid-state reaction method. The compound has a cubicmore » spinel structure [Fd-3m (227)] similar to MgFe{sub 2}O{sub 4} with lattice parameters of a = 8.3939 Angstrom-Sign , V = 591.42 Angstrom-Sign {sup 3}, Z = 8 and {rho} = 4.30 g/cm{sup 3}. This ceramic has a low sintering temperature ({approx}1050 Degree-Sign C) and good microwave dielectric properties with relative permittivity of 21.4, Q Multiplication-Sign f value of 35,000 GHz and {tau}{sub f} value of -22 ppm/ Degree-Sign C. Furthermore, the addition of BaCu(B{sub 2}O{sub 5}) (BCB) can effectively lower the sintering temperature from 1050 Degree-Sign C to 900 Degree-Sign C and does not induce much degradation of the microwave dielectric properties. Compatibility with Ag electrode indicates that the BCB added CoLi{sub 2/3}Ti{sub 4/3}O{sub 4} ceramics are good candidates for LTCC applications.« less