Technique of CeF3 impurity concentration control in LaF3 crystals by means of the UV absorption spectra

The presence of impurities in the crystals has an important influence on their properties. A sensitive method of the impurity control in the crystals without their destruction is the investigation of their absorption spectra. In this work we have studied the LaF3 tysonite crystals widely used as the laser matrices. The LaF3 crystals were grown from the melt by Bridgman-Stockbarger method using the reagents with trade mark high pure and chemical pure. The crystal absorption spectra were recorded in the range of 200-300 nm and the obtained results have shown that the crystals grown from the high pure reagents had no absorption bands in the UV region and the crystals grown from the chemical pure reagents had well defined characteristic absorption bands at (lambda) = 205, 218, 235, 248 nm. Spectral experiments have confirmed the assumption that the UV-absorption bands in the latter crystal samples were caused by the presence of CeF3 impurity in the chemical pure reagents. A technique was developed for evaluation of CeF3 content in LaF3 crystals and in chemical pure mixture of LaF3 with the accuracy +/- 0.0005 mol.%.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.