Method for preparing large-size two-dimensional layered metal thiophosphate crystal

A method for preparing a two-dimensional layered metal thiophosphate crystal, comprising the following steps:

• 1) Weighing raw materials comprising indium spheres, phosphorous lumps and sulfur granules according to a predetermined amount and a predetermined molar ratio, mixing the raw materials, and using iodine as a transport agent and potassium iodide as a molten salt;
• 2) Adding the raw materials, the iodine and the potassium iodide to a reaction vessel together, and vacuum sealing the reaction vessel under a predetermined pressure, and then subjecting the reaction vessel to a high-temperature reaction, wherein the high-temperature reaction is 600-700° C.;
• 3) Taking out products after the high-temperature reaction, and washing the products to remove residuals of the iodine and the potassium iodide from the products and obtain the two-dimensional layered metal thiophosphate crystal.