ELSEVIER MATERIALS CHEMJSHTR&dD Materials Chemistry and Physics 46 ( 1996) 84-9 1 Judd-Qfelt intensity analysis and spectral studies of Pr( III) ions in alkali zinc borosulphate glasses C.K. Jayasankar *, V.V. Ravi Kanth Kumar Department of Physics, S.K. University Post-Graduate Centre, Post Box No. 50, Kurnool518 001 (A.P.), India Received 6 September 1995; accepted 29 December 1995 Abstract Judd-Ofelt parameters for Pr3+ ions in zinc borosulphate glass (ZBS) and alkali zinc borosulphate glasses (RZBS, R = Li, Na, K or Gd) were derived from the intensities of the integrated absorption bands. The radiative transition probabilities A, radiative lifetimes rs, branching ratios PR and integrated emission cross sections era were calculated for the excited states 3P0, 3P1 and ‘D2. The resulting spectroscopic parameters are compared with the corresponding reported values. Keywords: Judd-Ofelt parameters; Oscillator strengths; Praseodymium-doped glasses; Radiative properties 1. Introduction Glasses doped with rare earth (RE) ions have been an object of interest because of their potential applications in the production of optical colourless glasses, optical filters and luminescent materials [ 11, The elaboration of RE-based glasses for these applications requires an accurate knowledge of the radiative properties of RB ions in glasses. The Judd- Ofelt theory, developed to calculate the intensities of forced electric dipole transitions between 4f states, allows the phe- nomenological parameters related to the radiative properties of a particular glass composition to be determined [ 2,3]. Widely used, it has proved to be a powerful tool for the systematic investigation and selection of glasses for specific purposes. The optical, radiative and nonradiative properties of Pr3+ ions have been studied in numerous glass hosts [ 4- 101. Recently, electron paramagnetic resonance (EPR) and optical studies of transition metal and RP ions doped in alkali zinc borosulphate glasses have been reported [ 1l-131. Since the intensity parameters and radiative properties have not previously been reported for Pr3+ in zinc borosulphate glass (ZBS) and alkali zinc borosulphate glasses (RZBS, R = Li, Na, K or Gd), the present work is aimed at elucidating these spectral features. * Present address: Department of Physics, S.V. University, Tirupati, 517 502 India. 0254-0584/96/$15.00 0 1996 Elsevier Science S.A. All rights reserved prrsn754-nSX4(9h~nllhl-n 2. Theory The behaviour of RE ions in glasses is similar to that of RE ions in inorganic crystals of low symmetry, except for inhomogeneous broadening of the spectra because of the mul- tiplicity of RE sites in glasses [ 141. Optical absorption spcc- tra of triply ionized RE ions originate from transitions between levels of the 4f”. The model Hamiltonian that describes the position of these levels for the Pr”+ ion is written as [ 10,15-211 &I = EA”G +~Fkf~+&Jso+oj(~+l) k +@(G2) +7&R,) +~P~~‘p^,+~Mb’lj (1) k 1 where k = 2,4,6; j = 0,2,4; and the operators vk, ds,, L, 8, fik, l;lj) and their associated parameters ( EAVG, F”, i&, a, p, y, pk and M’) are written according to conventional notation and meaning (with respect to the interactions they represent). The operators represent angular integrals and their associated parameters represent radial parameters [ 17,201. The method developed by Racah [ 161 is used to evaluate the matrix elements of the free-ion model Hamiltonian within the I4fzSLJ > basis. In general, the various radial integrals cannot be determined accurately a priori. A semiempirical approach is adopted in which these radial integrals are treated as variable parameters in fitting the eigenvalues of thereduced basis set free-ion Hamiltonian matrix to the observed band positions. Thus a total of 14 parameters, namely, central field