用固相法制备了Er-Mg和Er-Mn掺杂BaTiO3陶瓷, 并研究烧结气氛对其微结构和电性能的影响. XRD显示样品经不同气氛烧结后均是赝立方相, 在空气中烧结Er的固溶度约3.0mol%~4.0mol%, 但还原气氛会抑制Er在BaTiO3中的固溶度, 导致焦绿石相Er2Ti2O7出现. SEM显示Mg能抑制Er2Ti2O7晶粒的长大, 而Mn促进此第二相的晶粒生长. 研究表明, 烧结气氛对受主离子的固溶度的作用将改变壳芯结构中壳/芯体积比, 并且Mn离子的价态随气氛变化将移动居里点, 从而显著影响电容变化率温度特性. 采用适当的气氛烧结能够使两种介质都满足X8R要求.
Er-Mg and Er-Mn doped BaTiO3 systems were prepared by solid state reaction and the effects of sintering atmosphere on their microstructures and electrical properties were researched. XRD indicates that both samples sintered in different atmospheres have pseudocubic structure. For both specimens, the solubility limit of Er in BaTiO3 is about 3.0mol%--4.0mol%, however the reducing atmosphere can suppress the solid solubility of acceptors such as Er, which lead to the formation of pyrochlore-type Er2Ti2O7. SEM shows that Mn ions promote grain growth of Er2Ti2O7 secondary phase, but contrarily Mg ions inhibit it. The results suggest that due to the effect of various sintering atmosphere, the solid solubility change of acceptors can affect the core/shell volume ratio in the grains, as well as the valence variety of Mn ions can shift the Curie temperature. Thus the capacitance-temperature characteristics are dramatically improved and two kinds of dielectrics sintered under the proper conditions can meet X8R specification.
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