Phase formation, sintering behavior and microwave dielectric properties of bismuth and manganese co-doped [(Pb, Ca) La](Fe, Nb)O3+δ solid solution
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The phase formation, sintering behavior and microwave dielectric properties of Bi2O3 and MnO2 co-doped [(Pb, Ca) La](Fe, Nb)O3+δ (PCLFN) ceramics were investigated. The Bi2O3 and MnO2 binary dopants formed stable and low melting temperature solubilities at grain boundary which resulted in an effectively lowered sintering temperature by about 140 °C a more rapid sintering process and enhanced bulk densities. Sintering procedure has significant effect on grain size and porosities in ceramics. With high sintering temperature and time, the evaporation of PbO scaled up from surface toward the bulk and resulted in a Pb2+ deficient layer up to 0.25 mm depth under ceramic surface. Investigation of sintering dynamic revealed that either volume diffusion or second-order interface mechanism controlled the grain growth in present system. An optimal microwave dielectric properties of εr = 91.1, Qf = 4,870 GHz and τf = 18.5 ppm/°C could be obtained in Bi2O3 and MnO2 co-doped [(Pb, Ca) La](Fe, Nb)O3+δ ceramics sintered at 1,050 °C for 4 h when the quality ratio of Bi2O3/MnO2 was 1 and the doping content w = 1 wt%.
KeywordsMnO2 Sinter Temperature Bi2O3 Microwave Dielectric Property Sinter Time
This work was supported by the National Nature Science Foundation of China under Grant No. 50371056, the Key Items of Hubei Education Committee with the granted No. 030-094105 the Key Lab Item 2006 of Material Physics and Chemistry of Hubei University and the Nature Science Foundation of Hubei University granted 030-095132.
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