Ternary inorganic compound crystal and preparation method and application thereof

A method for preparing a ternary inorganic compound crystal, comprising the steps of:

• weighing calcium nitrate, aluminium nitrate, and ammonium dihydrogen phosphate respectively according to the molar ratio among calcium, aluminium, and phosphorus in the molecular formula Ca8Al12P2O31;
• adding the calcium nitrate, aluminium nitrate, and ammonium dihydrogen phosphate to a water to give a mixed solution;
• and heating the mixed solution to 70° C.-80° C. with continuously stirring, the mixed solution form a sol and further form a gel after distillation of water, and presintering the gel at 600° C.-800° C., to obtain a presintered product;
• and
• pressing the presintered product into blanks, then calcinating the blanks at 1550° C.-1570° C. for 1.5-2.5 hrs, and cooling them to room temperature, to obtain the ternary inorganic compound crystal.