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The local structure and interaction between Mn 2+ and Mn3+ ions in borate glasses

I. ARDELEAN1, M. FLORA2,*

Affiliation

  1. Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania
  2. Department of Physics, University of Oradea, 410087 Oradea, Romania

Abstract

The oxide glasses are non–crystalline solid materials which atoms are disposed likewise crystals, but the arrangement is not steady they have only local order. Glasses may become host matrices for transition metal ions. The content of transition metal oxide dissolved in glass without separation of microcrystalline precipitates depends of the nature the involved ions, matrix composition and the equilibrium temperature of melting. Paramagnetic metal ions incorporated in borate glasses as a spectroscopic probe are studied in order to characterize the glass local structure. Magnetic susceptibility measurements have been performed on xMnO·(100−x)[2B 2O 3·MO] glasses where MO→ SrO, CdO,As 2O 3 or PbO with 0< x ≤ 50 mol%. The data give evidence that the manganese ions in this glasses are in Mn 2+ and Mn 3+ valence states, which explains their magnetic behaviors. This data are analyzed comparatively. The manganese ions provide information about many specific aspects like geometry of structural units of the glass network, the character of the chemical bonds in glasses as well as the polyhedral coordination (local symmetry) of paramagnetic metal ions. Manganese ions were detected as magnetically isolated for glasses with x < 20 mol % and as antiferromagnetic coupled when x ≥ 20 mol % MnO. Both Mn 2+ and Mn 3+ ionic species are responsible for the magnetic behavior of the investigated glasses. The paper aims to presented the results concerning: the temperature dependence of the reciprocal magnetic susceptibility, the composition dependencies of the molar Curie constant, C M and the paramagnetic Curie temperature θp. The molar fraction of manganese ions in this two possible valence states were estimated in first approximation using relations: xμeff2 = x1μ2Mn2+ + x2μ2Mn3+ , x = x1 + x 2 where x1 and x2 are the molar fraction of Mn 2+ and Mn 3+ ions, respectively. The obtained values are shown in tables in this paper. The studied materials present both practical and theoretical interest..

Keywords

Borate glass, Manganese ions, Magnetic sussceptibility.

Submitted at: Nov. 18, 2009
Accepted at: Nov. 19, 2009

Citation

I. ARDELEAN, M. FLORA, The local structure and interaction between Mn 2+ and Mn3+ ions in borate glasses, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 11, pp. 1865-1869 (2009)