Growth and Characterization of Doped CaF2 Crystals

Abstract

Crystallization process is essentially a phenomenon of periodic arrangement of the constituent ions of a given material obtaining a crystalline state. There are many methods of crystal growth. Controlled solidification in a crucible of a molten material is one of the most used method. First used by Bridgman [Bridgman, 1925], improved by Stockbarger [Stockbarger, 1949] this technique is used successfully (about 40% of production of artificial crystals) because it is a simple technology and does not require complicated control systems. In the design of vertical Bridgman-type technique (VB) it is important to predict the thermal profiles in the growing crystal. The position and shape of the solidification interface and the axial and radial thermal gradients are of particular interest in controlling the growth process. The relatively high axial temperature gradient necessary in order to obtain crystals with large diameters (Φ > 20mm) cannot be obtained by means of a single heating element; two or more independently controlled heaters are necessary. The temperature gradient is directly dependent on the "isolated" zone between the hot and cold zones [