This work reports on the study of the influence of temperature gradient in the furnace and the pulling rate on the position and the shape of the crystal/melt interface in a model system of lead chloride (PbCl₂) at simulated vertical Bridgman crystal growth. Its aim is to find suitable conditions for growth of high quality single crystals of lead halides and ternary alkali lead halides. Crystals of these compounds doped with rare earth elements are promising materials as hosts for mid-IR lasers [1, 2].

The temperature field in our experimental setup was measured by four thermocouples placed in specially prepared quartz ampoule with four asymmetrically positioned capillaries along the ampoule axis. Two experimental configurations were used: stationary and dynamic. The measurement at the stationary arrangement, at which the ampoule was held at fixed position, the thermocouples were pulled up in the capillaries by step of 1 mm/h, was described in detail in [3].

At the dynamic one the ampoule was pulled down by pulling rates of 1 and 3 mm/hour through the same temperature gradients as those used in the stationary arrangement. When the ampoule reached the same position in the furnace as in the stationary arrangement, the temperature field was measured.

In the stationary arrangement, temperature gradient of 35 K/cm, and small volume of the crystalline phase in the ampoule, the shape of the crystal/melt interface obtained by temperature measurements was markedly convex. While at the dynamic arrangement the interface shape was planar and its position was lower by 2 – 3 mm than the position determined at the stationary arrangement. This can be explained by release of the latent heat.

Temperature data were used as boundary conditions for a modeling of the temperature field and the melt flow in the studied system using COMSOL Multiphysics 4.1 software.

 This work was supported by the research project MSMT KONTAKT No. LH12150.

[1] T.T. Basiev, Yu.K. Danileiko, L.N. Dmitruk, B.I. Galagan, L.V. Moiseeva, V.V. Osiko, E.E. Sviridova, N.N. Vinogradova, Opt. Mat. 25 (2004) 295–299.

[2] L.I. Isaenko, I.N. Ogorodnikov, V.A. Pustovarov, A.Yu. Tarasova, V.M. Pashkov, Opt. Mat. 35 (2013) 620–625.

[3] R. Král, J. Crystal Growth 360 (2012) 162–166.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/28797 must be provided.