Study On CLNT Based LTCC Microwave Dielectric Materials

Recently, with the top speed development of mobile communication, Low-Temperature-Cofired Ceramics (LTCC) for microwave applications represents a key position in mobile products, because of the design and functional benefits upon the miniaturization of multilayer devices with high reliability and low cost. In order to meet the requirement of LTCC technology, much attention have been paid to the low temperature sintered microwave dielectric ceramics with high performance.CLNT (Ca[(Li1/3Nb2/3),Ti]O3-δ) ceramics have received much attention because of the good dielectric properties and low sintering temperature. However, the sintering temperature of this material is still too high to use Ag or Cu as an internal electrode in multilayer devices. In this paper, ZnO-B2O3 glass was added as a kinds of sintering flux for CLNT. Prepared by high-energy ball milling, CLNT ceramics with 3 wt.% ZnO-B2O3 glass was sintered at 910℃. CLNT is a kind of complex perovskite compound. In order to increase CLNT's microwave dielectric properties and study the mechanics, the effects of B-site substituted with Ti4+ and Zr4+ on low-temperature sintered CLNT ceramics was investigated as well.Low-temperature sintering of CLNT ceramics was studied. Firstly, Low-melting oxide B2O3 and Bi2O3 was adoped as sintering flux, The dielectric properties of Ca[(Li1/3Nb2/3)0.9Ti0.1]O3?δwith 3 wt.% B2O3 and 5wt.% Bi2O3 sintered at 980℃for 4 h were Qf =13018 GHz,εr =53.73,τf =-8.9 ppm/℃; Qf =9971 GHz,εr =33.73,τf =-17.073 ppm/℃, respectively. Prepared by high-energy ball milling, Ca[(Li1/3Nb2/3)0.84Ti0.16]O3?δceramics with 3 wt.% ZB glass sintered at 910℃for 4 hours show dielectric properties as follows: Qf =13026 GHz,εr =32.25,τf =-36 ppm/℃.Ti4+ and Zr4+ for B-site substituted on low-temperature sintered CLNT ceramics was studied. With increased Ti4+ substituted, the degree of B-site ordering and Qf decreased;τf increased positively and approach to 0ppm/℃; When 0.21 mol Ti4+ substituted, the dielectric properties of CLNT+ZB ceramic were: Qf =8658 GHz,εr =31.14,τf =+0.5 ppm/℃at 940℃/4h, Qf =16061 GHz,εr =32.76,τf =-5 ppm/℃at 960℃/4h.When Ti4+ and Zr4+ substituted together, As Zr4+substituted increasing, Qf changed nonlinear;τf increased negatively. In addition, the relationship between microstructure and dielectric properties was investigated.The CLNT ceramic prepared meet the demand of LTCC technology and can be used for multilayer devices such as band pass filter and so on.