Spectroscopic properties and luminescence behaviour of europium doped lithium borate glasses J. Anjaiah a,b,n , C. Laxmikanth a , N. Veeraiah c a Department of Physics, The University of Dodoma, Tanzania, East Africa b Department of Physics, Geethanjali College of Engineering & Technology, Keesara, RR Dist., Hyderabad 501 301, India c Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar, Guntur 522 510, AP., India article info Article history: Received 16 July 2014 Accepted 23 July 2014 Available online 4 August 2014 Keywords: Optical absorption Fluorescence Judd–Ofelt parameters Borate glasses Europium abstract Li 2 O–MO–B 2 O 3 (MO¼ZnO, CaO and CdO) glasses doped with europium are prepared by using the melt quenching technique to study their absorption and luminescence properties to understand their lasing potentialities. The XRD pattern of the glasses confirmed the amorphous nature and the IR spectra reveal the presence of BO 3 and BO 4 units in the glass network. Judd–Ofelt intensity parameters Ω λ (λ ¼2, 4, 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. The J–O parameters have been used to calculate transition probabilities (A), lifetime (τ R ), branching ratios (β R ) and stimulated emission cross-section ðσ P ) for the 5 D 0 - 7 F J (J ¼1–4) transitions of the Eu 3 þ ions. The decay from the 5 D 0 level of Eu 3 þ ions in these glasses has been measured and analysed. Branching ratios and stimulated emission cross-sections measured for all these glasses show that the 5 D 0 - 7 F 1 transition under investigation has the potential for laser applications. The high stimulated emission cross-section and branching ratios from the present glasses suggests their potential for infra red lasers. The study of the thermoluminescence is also carried out and the data suggests that the CdBEu glass is suitable for thermoluminescence emission output among the three Eu 3 þ doped glasses. & 2014 Elsevier B.V. All rights reserved. 1. Introduction Optical properties of rare-earth [RE] doped glasses are exten- sively studied for their potential applications in the fields of lasers, fluorescent display devices, optical detectors, waveguides and fibre amplifiers [1–4]. There has been a considerable attention in the study on optical, structural and dielectric behavior of borate based glasses [5–8]. It is well known that boric acid (B 2 O 3 ) is one of the good glass formers and can form glass alone with good transparency, high chemical durability, thermal stability and good rare-earth ion solubility [9]. Among the three modifier oxides chosen to mix in the present glass system, viz., CaO, ZnO and CdO; ZnO is expected to shorten the time taken for solidification of glasses during the quenching process and glasses containing ZnO have high chemical stability and less thermal expansion. Their wide band gap, large exciton binding energy and intrinsic emitting property make them as promising candidates for the development of optoelectronic devices, solar energy concentrators, ultraviolet emitting lasers and gas sensors [10]. Both ZnO and CdO are thermally stable and appreciably covalent in character [11]. Addition of alkaline-earth oxide CaO into these glass matrices is expected to increase the resistance of the glasses to the moisture [12]. The glass containing Li 2 O as network modifier was seen as bubble free, highly stable and moisture resistant, suitable for a systematic optical analysis [13]. In the present work, the trivalent europium ion Eu 3 þ (4f 6 ) has been chosen as a dopant due to its well characterized visible spectrum with pure luminescence transitions. Also the lower energy level structure of the Eu 3 þ ion is relatively effortless compared to other RE ions. Normally, the trivalent europium ion, Eu 3 þ emits narrow band, almost monochromatic with longer lifetime and it can used as a red emitting material for field emission technologies and LEDs. The excitation and emission transitions are due to the transitions among the 4f electronic states in the trivalent RE ions, which are highly sensitive to the symmetry, structure of the local environment and phonon energy of the host matrix [14,15]. Recently, Eu 3 þ ion doped sodium–lead borophosphate glasses for red light emission were reported by Nallamala Kiran [16]. Spectroscopic investigation and optical characterization of Eu 3 þ ions in K–Nb–Si glasses were reported by Mohan et al. [17]. Concentration dependent luminescence studies on Eu 3 þ doped telluro fluoroborate glasses were reported by Vijayakumar et al. [18]. Nico et al. [19] reported the Eu 3 þ luminescence in aluminopho- sphate glasses. Rojas et al. [20] reported the structural, thermal and optical properties of CaBO and CaLiBO glasses doped with Eu 3 þ . Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/physb Physica B http://dx.doi.org/10.1016/j.physb.2014.07.070 0921-4526/& 2014 Elsevier B.V. All rights reserved. n Corresponding author at: Department of Physics, The University of Dodoma, Tanzania, East Africa. Tel.: þ255 768224886. E-mail address: anjaiah.juluru@gmail.com (J. Anjaiah). Physica B 454 (2014) 148–156