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 (H sub(3)BO sub(3)), calcium hydroxide [Ca(OH) sub(2)], strontium carbonate (SrCO sub(3)) and barium hydroxide octahydrate [Ba (OH) sub(2).8H sub(2)O] are mixed with strontium carbonate (SrCO sub(3)) and kaolin (Al sub(2)O sub(3).2SiO sub(2).2H sub(2)O) to prepare SrAl sub(2)Si sub(2)O sub(8 ) ceramics with a sintering temperature of 950 degree C. According to chemical compositions of flux agents B sub(2)O sub(3), CaO.2B sub(2)O sub(3), SrO.2B sub(2)O sub(3) and BaO.2B sub(2)O sub(3), 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 SrAl sub(2)Si sub(2)O sub(8 ) ceramics. In addition, the Sr element in SrAl sub(2)Si sub(2)O sub(8 ) ceramics are partly substituted with Ba and Ca elements, respectively, to investigate the low-temperature sintering behavior of partly substituted SrAl sub(2)Si sub(2)O sub(8 ) ceramics. The results indicated that the addition of flux agents to SrAl sub(2)Si sub(2)O sub(8 ) ceramics can availably achieve the densification sintering of SrAl sub(2)Si sub(2)O sub(8 ) ceramics at 950 degree C, whereas the substitution of Sr with Ca or Ba have a great effect on sintering behaviors and dielectric properties of SrAl sub(2)Si sub(2)O sub(8 ) ceramics. Additionally, main crystal phases of the SrAl sub(2)Si sub(2)O sub(8 ) ceramics are monoclinic- SrAl sub(2)Si sub(2)O sub(8 ) and small quartz, but the evolution of crystal phases also depend on flux agents.