Growth of pure and doped Rb2ZnCl4 and K2ZnCl4 single crystals by Czochralski technique

High-quality single crystals of Rb2ZnCl4 and K2ZnCl4, pure or doped with Cu , Mn, Cd, Tl, Sn, Pb and In cations, were grown by Czochralski technique in argon atmosphere, using an experimental setup that allows direct visual ac cess to the whole growth zone. Slowly cooled crystals exhibit excellent cle avage properties. Fastly cooled crystals do cleave poorly. As shown by X-ra y diffraction studies, such K2ZnCl4 samples exhibit inclusions of the high- temperature Pmcn phase with lattice parameters a = 7.263(2) Angstrom, b = 1 2.562(2) Angstrom and c = 8.960(4) Angstrom in the P2(1) cn room temperatur e stable phase. ESR and optical spectroscopy studies revealed the localizat ion and valence state of the cation dopants. (C) 1999 Elsevier Science B.V. All rights reserved.