Papers by Author: Qiang Li

Abstract: Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) solid solutions with composition near the morphotropic phase boundary (MPB) (33mol% PT) were successfully synthesized by the molten salt synthesis (MSS) method at 800°C for 30min using Li2SO4-Na2SO4 and NaCl-KCl molten salts as a medium of reaction, respectively. The influences of processing parameters, such as temperature, time, and type of salts, on the formation and the micrographs characteristics of the PMN-PT powders were discussion. It was found that the PMN-PT powder obtained by the MSS method has a relatively uniform size distribution and a better dispersivity of particle, and an average size of PMN-PT particles with smooth surface was around 0.3∼0.5 μm. With other conditions being kept same, chloride molten salt is more propitious to the formation of PMN- PT solid solutions, and improving the compositional homogeneity of PMN-PT powders.

Abstract: Ni-Zn ferrite ceramics were prepared from the blend of nano-sized powders and ultra-fine particles at the relative low sintering temperature (≤1200°C). The microstructure of the as-sintered samples characterized by SEM indicated that this process obstructed abnormal grain growth which often appeared in the Ni-Zn ferrite ceramics sintered from the nano-sized powders. The result of VSM measurements showed that the ratio of nano-sized powders to ultra-fine particles effected the initial permeability (μi) of the as-sintered samples. Optimum initial permeability can be obtained by adjusting the ratio as 1:1.

Abstract: (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 ((1-x)PMN-xPT, PMN-PT) with composition near the morphotropic phase boundary (MPB) were prepared by the columbite precursor method and the rutile precursor method respectively. Attention has been focused on the influence of process on microstructure of PMN-PT ceramics. The results show that the average grain size of ceramics is insensitive to composition for both above processes. The refinement and homogeneity on grain size in the rutile precursor method is better than that in the columbite precursor method.

Abstract: Single perovskite phase PMN-PT powders had been synthesized using molten salts method. The powders of PMN-PT synthesized by MSS had submicrometer particle size and high sinterability, which beneficial to an enhancement of the densification process and a decrease of the sintering temperatures. These advantages have an important bearing on the dielectric properties of these materials. The density of ceramics sintered at 1175°C was up to 98% of the theoretical density. These ceramics had excelled dielectric and piezoelectric properties.