The paper presents both theoretical and experimental study of spectral properties of the lead and cadmium tungstate crystals doped with some rare earth (RE) ions (Pr³⁺, Sm³⁺, Dy³⁺, Eu³⁺). Optical and luminescence properties of these crystals were investigated in a wide temperature region at the different excitation and registration wave length. Analysis of the Stark levels structure allows us to do conclusion about existence of two type of the emission centers formed on a basis of the RE³⁺ ions arranged in the different positions of the PbWO₄ and CdWO₄ crystal lattices.
Calculations of the electronic structure of the pure and doped crystals also were carried out.
Two methods of calculations are applied. Electronic band structures of perfect crystals are calculated by full-potential LAPW method using WIEN2k program code [1]. Electronic structures of luminescence centers of the crystal were investigated in cluster approach. The electronic structures of molecular clusters constructed by 9 - 14 formula units are ab-initio calculated by the Restricted Hartree-Fock method using GAMESS program [2]. Results of both calculations are compared and analyzed together with experimental results on luminescence and absorption spectra of the tungstate crystals. General remarks concerning the applicability of band theory and cluster methods for investigation of the electronic properties of wide-gap dielectric crystals are made.
Comparison between electronic structure of the pure and doped crystals was done.
The work is supported by STCU Project#2042.

[1] P. Blaha, K. Schwarz, G. Madsen, D. Kvasnicka and J. Luitz, WIEN2k, An Augmented Plane Wave Local Orbitals Program for Calculating Crystal Properties (Karlheinz Schwarz, Techn. Universität Wien, Austria), 2001. ISBN 3-9501031-1-2
[2] Schmidt M.W., Baldridge K.K., Boatz J.A., et al. // J.Comput.Chem. - 1993. - v. 14. - p. 1347.

• 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/1956 must be provided.

1. Synthesis and luminescent investigation of KTiOPO₄ and NaTi₂(PO₄)₃ crystals doped with rare earth ions
2. Local complex emission centers in the wide band gap materials: theoretical predictions and experimental diagnostic possibilities