Sintering Process and Dielectric Properties of Tm2O3 Doped K0.5Na0.5Nb0.7Ta0.3O3 Ceramics
The 99.7％K0.5Na0.5Nb0.7Ta0.3O3·0.3％Tm2O3 ceramic powders prepared by solvothermal method was sin-tered into ceramics by pressure sintering process.The effects of holding time and sintering temperature on phase structure,microstructure,density and dielectric properties were systematically investigated.The results show that sintering temperature and holding time have little effect on the room temperature crystal structure of ceramic and all the specimens exhibit a pure perovskite structure which strongly affects the surface morphology,density and dielectric properties.When sintered at 1180 ℃ for 1-2 h,the density and dielectric constant increase with the extension of holding time;when sintered at 1180-1200 ℃ for 2 h,with the increase of sintering tempera-ture,the density and dielectric properties of ceramics first increase and then decrease.The 0.3％Tm2O3 doped 99.7％K0.5Na0.5Nb07Ta03O3 ceramic sintered at 1185 ℃ for 2 h exhibits excellent properties:εr100 kHz=1900,tanδ100kHz-0.022,Tc=182℃.
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