Low-temperature sintering behavior and properties of monoclinic-SrAl^sub 2^Si^sub 2^O^sub 8^ ceramics prepared via an aqueous suspension milling process

In this work, by an aqueous suspension milling process, boric acid (H3BO3), calcium hydroxide [Ca(OH)2], strontium carbonate (SrCO3) and barium hydroxide octahydrate [Ba (OH)2·8H2O] are mixed with strontium carbonate (SrCO3) and kaolin (Al2O3·2SiO2·2H2O) to prepare SrAl2Si2O8 ceramics with a sintering temperature of 950 °C. According to chemical compositions of flux agents B2O3, CaO·2B2O3, SrO·2B2O3 and BaO·2B2O3, raw materials boric acid, calcium hydroxide, strontium carbonate and barium hydroxide octahydrate were introduced to the suspension slurries of strontium carbonate and kaolin to decrease the densification sintering temperature of SrAl2Si2O8 ceramics. In addition, the Sr element in SrAl2Si2O8 ceramics are partly substituted with Ba and Ca elements, respectively, to investigate the low-temperature sintering behavior of partly substituted SrAl2Si2O8 ceramics. The results indicated that the addition of flux agents to SrAl2Si2O8 ceramics can availably achieve the densification sintering of SrAl2Si2O8 ceramics at 950 °C, whereas the substitution of Sr with Ca or Ba have a great effect on sintering behaviors and dielectric properties of SrAl2Si2O8 ceramics. Additionally, main crystal phases of the SrAl2Si2O8 ceramics are monoclinic- SrAl2Si2O8 and small quartz, but the evolution of crystal phases also depend on flux agents.