Journal of Alloys and Compounds 393 (2005) 51–56 Crystal-field analysis of Er 3+ ions in yttrium aluminium borate (YAB) single crystals M. Dammak Laboratoire de Physique Appliqu´ e, D´ epartement de Physique, Facult´ e des Sciences de Sfax, 3018 Sfax, Tunisia Received 3 March 2004; received in revised form 30 September 2004; accepted 4 October 2004 Available online 8 December 2004 Abstract Crystal-field energy levels of Er 3+ ions doped in YAB single crystals were fitted to the parameters of semi empirical Hamiltonian including J-mixing. A simulation of the energy level scheme is carried out. The effective Hamiltonian includes elementary interactions such as columbic, spin–orbit, two- and three-body interactions. The crystal-field effect is introduced through the six non-zero crystal-field parameters allowed by D 3 symmetry site occupied by the rare earth. Very satisfactory correlations were obtained between calculated and experimental levels, with root mean square deviation (r.m.s.) of 15.5 cm -1 . These results are compared with those reported for Nd 3+ and Dy 3+ ions in the same host and with Er 3+ ions in other hosts. The concordance between the crystal-field strength parameters indicates the consistence of our analyses. The calculated wave functions of the system are used to predict the magnetic g-factors of the 4 I 15/2 ground state. © 2004 Elsevier B.V. All rights reserved. Keywords: YAB:Er 3+ ; Crystal-field parameters; g-Factors 1. Introduction According to its absorption, luminescence and optical properties, YAl 3 (BO 3 ) (YAB) is a promising crystal for non- linear optical applications. Indeed, the yttrium aluminium borate shows the highest known non-linear optical coeffi- cient among the huntite borates [1], it has good physical and chemical stability, and the Y 3+ ions can be easily replaced with other trivalent rare earth ions even at high concentra- tions to give optically active materials. In particular, erbium doped yttrium aluminium borate, has been demonstrated to be a potential self-frequency-doubling laser crystal [2], fur- thermore, the Er 3+ ion is the most attractive candidate as a dopant for infrared-pumped visible luminescence and laser emission [3,4]. Despite possible laser application, only a few papers are dealing with Er 3+ :YAB crystals. The first detailed spectroscopic studies were published earlier [5,6]. These pub- lished works focused primarily on measurements and anal- yses of optical excitation and emission spectra. From these E-mail address: mohamed.dammak@fsm.rnu.tn. studies many of the crystal-field energy levels split out of the 13 lowest-energy 4f 11 [SL] J multiplets of Er 3+ were located. However, these levels were not characterized with respect to symmetry type, and no attempts were made to analyze the observed energy-level structure in terms of model crystal- field Hamiltonian. The analysis of crystal-field interactions and electronic energy-levels structure in Er 3+ :YAB is of con- siderable interest. In this work, results obtained from optical absorption and emission measurements [6] are analyzed in terms of a one-electron model Hamiltonian that assumes D 3 crystal-field symmetry of the Er 3+ sites in YAB. These re- sults are compared with those reported for Nd 3+ and Dy 3+ ions in the same host and with Er 3+ ions in other hosts. Tak- ing advantage of the fitting wave functions, the paramagnetic g-tensors was predicted for the 4 I 15/2 ground state of Er 3+ . 2. Experimental support and crystal structure The crystal-field analysis is performed on erbium doped yttrium aluminium borate single crystals grown by the top 0925-8388/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2004.10.006