Effects of MnO2 doping on microstructure and microwave dielectric properties of Ba4.2Nd9.2Ti18O54–NdAlO3 ceramics

Abstract

MnO2 doped Ba4.2Nd9.2Ti18O54–NdAlO3(13 wt%) (BNT–NA) microwave dielectric ceramics with the near zero τ f and the wide range of sintering temperature were prepared by conventional solid state method. The effects of Mn4+ doping on the microstructures and microwave dielectric properties of BNT–NA ceramics were investigated. XRD patterns showed only a single BaNd2Ti5O14 phase was identified in all samples and there was no second phase. The sintering temperature decreased from 1,380 to 1,320 °C as MnO2 content increased from 0.1 to 0.9 wt%. The MnO2 doped BNT–NA ceramics could be densified at a lower sintering temperature. The MnO2 additive had a positive effect on lowing sintering temperature of BNT–NA ceramics. The τ f varied from negative to positive with the increase of MnO2. Excellent microwave dielectric properties were achieved in Ba4.2Nd9.2Ti18O54–NdAlO3 ceramics doped with 0.3 wt% MnO2 and sintered at 1,380 °C for 2 h: e r = 66.5, Q × f = 13,948 GHz, τ f = 0.4 ppm/°C.