Synthesis and thermal behavior of the dawsonite-type solid solution K1−x(NH4)xAl(OH)2CO3

This paper reported the hydrothermal synthesis and thermal behavior of a novel kind of dawsonite-type solid solution K1−x(NH4)xAl(OH)2CO3 (x = 0.2-0.93). The effects of NH4+/K+ molar ratio in the starting reactants and the hydrothermal reaction time on the composition of K1−x(NH4)xAl(OH)2CO3 were investigated. In addition, the influence of the composition on the thermal stability of the solid solution was studied by DTA/TG analyses. It was indicated that compound K0.44(NH4)0.56Al(OH)2CO3 (x = 0.56) is the most thermally stable one among all the dawsonite type solid solutions. Furthermore, K-β-Al2O3, a solid state K+ ion conductor was prepared by calcining K0.19(NH4)0.81Al(OH)2CO3 at 1250 °C.