STRUCTURAL AND MAGNETIC BEHAVIOUR OF SOME OXIDE GLASSES CONTAINING CERIUM IONS

E.Culea1, I.Bratu2, M.Neumann3, Lidia Pop1

1Technical University, C.Daicoviciu st. no. 15, Cluj-Napoca, 400020, Romania
2National Institute for Research and Development of Isotopic and Molecular Technologies, Str.Donath 103, Cluj-Napoca, Romania
3University of Osnabruck, Germany

As a part of an on-going investigation of structural, spectroscopic and magnetic behaviour of oxide glasses containing rare earth ions [1], we studied some glasses containing cerium ions. Glass systems with the xCeO2(1-x)(Bi2O3.B2O3) and xCeO2(1-x)(Bi2O3.PbO) compositions (where x≤0.30) were prepared and studied by means of IR spectroscopy and magnetic susceptibility measurements.
The X-ray investigation reveals only the presence of diffraction patterns characteristic of the amorphous state.
The IR spectroscopic spectra present the features characteristic of the host glass matrices, Bi2O3.B2O3 and Bi2O3.PbO [1]. The addition of the cerium oxide produces only weak modifications of the IR spectral features that may be related to some changes of the basic structural units of the host glass matrices. The compositional evolution of the IR spectroscopic data suggests that the cerium ions play a network modifier role in the studied glass systems [1].
Magnetic susceptibility measurements show a Curie-Weiss type magnetic behaviour with very small paramagnetic Curie temperature values. The magnetic moment values per cerium ion were lower than 2.56 B, the value assigned to the Ce3+ free ions [2]. This suggests that cerium ions are present in the host glass matrix at least in two valence states, probably 3+ and 4+, where only the 3+ ions represent magnetic species. Based on the Curie constant values the fraction of the Ce3+/Cetotal was determined.

References:
1.	Culea E., Pop L., Simon V., Neumann M., Bratu I.: Spectroscopic and magnetic behaviour of xNd2O3(1-x)(Bi2O3.PbO) glasses, J Non-Crystalline Solids 337, pp.62-67, 2004.
2.	Burzo E.: Fizica fenomenelor magnetice, vol.1, Editura Academiei, Bucuresti, 1979.