Compounds Alkali Metal Borophosphates, Alkali Metal Borophosphates Nonlinear Optical Crystals as well as Preparation Method and Application thereof

The preparation method for the alkali metal borophosphates A3B11P2O23(A=K, Rb, Cs) nonlinear optical crystals adopt a high-temperature solid-state reaction method, a hydrothermal method or a solution method based on the following specific operation steps:

• A3B11P2O23 (A=K, Rb, Cs) polycrystalline powder with the stoichiometric ratios (A:
• B:P=3:11:2) or a mixture of the A3B11P2O23 (A=K, Rb, Cs) polycrystalline powder with fluxing agent is heated to obtain a mixed melt. Or directly heat the mixture of the potassium/rubidium/cesium-containing compound, boron-containing compound and phosphorus-containing compound or the mixture of potassium/rubidium/cesium-containing compound, boron-containing compound and phosphorus-containing compound and fluxing agents to obtain a mixed melt. The crucible of the liquid is placed in the crystal growth furnace, the seed crystal is fixed on the seed rod, and the seed crystal is brought down to the liquid surface of the mixed melt or in the mixed melt for melting back to the saturation temperature;
• cooling or constant temperature growth. Finally, alkali metal borophosphates nonlinear optical crystals were prepared;
• Or a. a mixture of a potassium/rubidium/cesium-containing compound, a boron-containing compound, a phosphorus-containing compound was combined with deionized water (0.1-50 mL) or boric acid 0.1-50 g, in which element potassium/rubidium/cesium in the potassium/rubidium/cesium-containing compound, elemental boron in the boron-containing compound, and elemental phosphorus in the phosphorus-containing compound are in a molar ratio of 1-5:7-16:0.5-4;
• b. The mixture was loaded into Teflon-lined autoclave and subsequently sealed;
• c. The autoclave was heated to 120-800° C., held for a period of time, and then cooled to room temperature;
• d. Open the autoclave and filter the solution containing crystals to obtain the transparent alkali metal borophosphates compounds.
• Or a mixture of a potassium/rubidium/cesium-containing compound, a boron-containing compound, a phosphorus-containing compound, and deionized water (0.1-400 mL) was placed in a beaker and stirred until dissolved completely. Then put the beaker on the heating table and heat it to 25-400° C. After a period of time, the series of alkali metal borophosphates nonlinear optical crystals are obtained. In order to further grow them, the seed crystals of the series of crystals were suspended in solution with fine platinum wires. In order to reduce the evaporation of water, the beaker is covered with a layer of polyethylene plate and pierced with dozens of millimeter sized holes. After a period of time, take out a centimeter size alkali metal borophosphates nonlinear optical crystals from the solution.