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Modelling and ab initio calculation of electronic structure of lead and cadmium tungstate crystals doped with the rare-earth ions

Sergiy G. Nedilko ,  Yuriy A. Khyzhnyy ,  Oksana V. Chukova 

Department of Physics, Taras Shevchenko Kyiv University, 6 Gloushkov avenue, Kyiv 252022, Ukraine

Abstract

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. Universit├Ąt 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.

 

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Related papers

Presentation: oral at E-MRS Fall Meeting 2004, Symposium H, by Sergiy G. Nedilko
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-04-30 14:43
Revised:   2009-06-08 12:55