Review Crystal field analysis of Er 3+ in Sc 2 O 3 transparent ceramics I. Trabelsi a,n , R. Maˆ alej a , M. Dammak a , A. Lupei b , M. Kamoun a a Laboratoire de Physique Applique ´e, Groupe de Physique The ´orique, De ´partement de Physique, Faculte´ des Sciences de Sfax, 3018 Sfax, Tunisie b National Institute of Laser, Plasma and Radiation Physics-ECS Lab., 077125 Bucharest, Romania article info Article history: Received 12 June 2009 Received in revised form 25 January 2010 Accepted 1 February 2010 Available online 6 February 2010 Keywords: Sesquioxides Rare earth Luminescence Crystal-field abstract A crystal field investigation of Er 3+ -doped Sc 2 O 3 transparent ceramics is presented. The established energy level diagram is analyzed with crystal-field Hamiltonian of C 2 symmetry including J-mixing effect. Very satisfactory correlations were obtained between 53 calculated and experimental Stark energy levels, with an rms of 7.7 cm 1 . These results are compared with those reported for other rare earth ions in the same host and with Er 3+ ions in other sesquioxides. The concordance between the crystal-field strength parameters indicates the consistence of our analysis. Furthermore, based on the extended electrostatic point charge model, a theoretical trend is proposed for rare earth ions in Sc 2 O 3 in comparison with Y 2 O 3 . Based on this trend, very satisfactory results are obtained for Yb 3+ ion in Sc 2 O 3 . & 2010 Elsevier B.V. All rights reserved. Contents 1. Introduction ...................................................................................................... 927 2. Theoretical considerations of the energy levels scheme ................................................................... 928 3. Free-ion functions ................................................................................................. 928 4. Crystal-field splitting calculations..................................................................................... 928 5. Results and discussion.............................................................................................. 929 5.1. Er 3+ :Sc 2 O 3 ................................................................................................. 929 5.2. Yb 3+ :Sc 2 O 3 .................................................................................................. 930 6. Conclusion ....................................................................................................... 930 References ....................................................................................................... 930 1. Introduction Rare earth doped sesquioxides yttria (Y 2 O 3 ), lutetia (Lu 2 O 3 ) and scandia (Sc 2 O 3 ) have been found to be interesting materials for many technological applications in the field of optical devices, such as luminescent displays, optical amplifiers and solid state lasers [1]. In particular, scandium oxide has recently attracted the attention of many researchers because of its interesting physical and chemical properties. Its high chemical stability, together with a high bulk refractive index value (1.90 at 400 nm) and a high ultraviolet cut-off (215 nm) [2], makes it interesting for numerous applications in the field of photonics and optoelectronics. More- over, due to its high thermal conductivity, trivalent rare earth doped scandia is very suitable host material for high power solid-states lasers [3]. The transparent ceramic technology developed for garnets has been used also to prepare rare earth doped transparent polycrystalline cubic sesquioxides. Recently, a series of spectroscopic experimental data on Er 3+ in Sc 2 O 3 trans- parent ceramics were reported [4] as interesting system for near infrared (3 and 1.5 mm) and visible upconversion laser emission. The cubic sesquioxides offer for substitution two different six- fold oxygen coordinated crystallographic sites with C 2 and C 3i symmetries. No other defective centers lines associated to ceramics were detected. Based on the observed IR and visible absorption and emission spectra of Er 3+ in Sc 2 O 3 transparent ceramics, an extended energy level scheme for Er 3+ in C 2 sites (up to 25000 cm 1 ) has been obtained [5]. However, these experi- mental energy levels are not investigated theoretically. In this work, we will calculate the Stark energy levels of Er 3+ in Sc 2 O 3 considering both free ion and crystal field parameters. A theoretical trend will be proposed for the rare earth ions in this host. ARTICLE IN PRESS Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jlumin Journal of Luminescence 0022-2313/$ - see front matter & 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jlumin.2010.02.004 n Corresponding author. E-mail address: trabelsiikram@yahoo.fr (I. Trabelsi). Journal of Luminescence 130 (2010) 927–931