Synthesis, characterisation, luminescence and defect centres in solution combustion synthesised CaZrO 3 :Tb 3 þ phosphor Vijay Singh a,n , S. Watanabe b , T.K. Gundu Rao b , Katharina Al-Shamery c , Markus Haase d , Young-Dahl Jho a,n a School of Information and Communications, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea b Institute of Physics, University of Sao Paulo, 05508-090 Sao Paulo/SP, Brazil c Physical Chemistry, Institute for Pure and Applied Chemistry and Center of Interface Science University of Oldenburg, 26129 Oldenburg, Germany d Department of Inorganic Chemistry I–Materials Research, Institute of Chemistry, University of Osnabrueck, Barbarastrabe 7, 49069 Osnabrueck, Germany article info Article history: Received 11 April 2011 Received in revised form 2 March 2012 Accepted 8 March 2012 Available online 27 March 2012 Keywords: Phosphors Combustion Tb 3 þ Photoluminescence Defect centres abstract Tb 3 þ doped CaZrO 3 has been prepared by an easy solution combustion synthesis method. The combustion derived powder was investigated by X-ray diffraction, Fourier-transform infrared spectro- metry and scanning electron microscopy techniques. A room temperature photoluminescence study showed that the phosphors can be efficiently excited by 251 nm light with a weak emission in the blue and orange region and a strong emission in green light region. CaZrO 3 :Tb 3 þ exhibits three thermo- luminescence (TL) glow peaks at 126 1C, 200 1C and 480 1C. Electron Spin Resonance (ESR) studies were carried out to study the defect centres induced in the phosphor by gamma irradiation and also to identify the centres responsible for the TL peaks. The room temperature ESR spectrum of irradiated phosphor appears to be a superposition of two distinct centres. One of the centres (centre I) with principal g-value 2.0233 is identified as an O  ion. Centre II with an axial symmetric g-tensor with principal values g O ¼1.9986 and g l ¼2.0023 is assigned to an F þ centre (singly ionised oxygen vacancy). An additional defect centre is observed during thermal annealing experiments and this centre (assigned to F þ centre) seems to originate from an F centre (oxygen vacancy with two electrons). The F centre and also the F þ centre appear to correlate with the observed high temperature TL peak in CaZrO 3 :Tb 3 þ phosphor. & 2012 Elsevier B.V. All rights reserved. 1. Introduction Alkaline-earth zirconates have attracted considerable attention due to their structural diversity and technological applications. Some perovskite compounds such as SrZrO 3 , CaZrO 3 and SrTiO 3 are of particular interest because they exhibit remarkable protonic con- ductivity when they are doped with acceptor ions [1–5]. Moreover, materials with the perovskite structure are known to show super- conductivity and remarkable electrical properties, including ferro- electricity and piezo-electricity [6–9]. Perovskite oxides having the general formula ABO 3 are getting special attention because of their applications in electrochemical devices such as capacitors, dielectric resonators for microwave, solid oxide fuel cells, oxygen sensors, oxygen separation membranes, hydrogen separators, hydrogen pumps, steam electrolysers, humidifiers and dehumidifiers, hydro- genation and dehydrogenation of hydrocarbons [1–15]. Among the alkaline earth zirconates, calcium zirconate is an interesting material for both mechanical and electrical applications such as filters, coatings, resonators and capacitors. CaZrO 3 ceramics have a rela- tively high permittivity and a high insulation resistance [8,16–18]. Also they show high ionic conductivity for solid electrodes in fuel cells and act as a microwave dielectric material [19]. It has been reported that for low cost applications, calcium zirconate can be considered as a good alternative to yttrium stabilized zirconia as it is a more stable compound than ZrO 2 –CaO and shows good corrosion resistance [20,21]. Calcium zirconate based materials have excellent gas sensitivity at high temperature and hence they have been studied for their potential use as a high temperature thermistor material [22]. Its high sensitivity response to methane (CH 4 ) makes CaZrO 3 a potential candidate material for hydrocarbon sensing [23]. It has one of the most distorted structures and its high-pressure behaviour is of special interest [24]. However, there is not much work related to rare earth doped calcium zirconate with perovskite structure. It is noted that there are only few reports on the synthesis of CaZrO 3 by low temperature methods and also CaZrO 3 has not received much attention as a luminescent host. For a better knowl- edge of the energy level structure of CaZrO 3 :Pr and CaTiO 3 :Pr, a Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/jlumin Journal of Luminescence 0022-2313/$ - see front matter & 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jlumin.2012.03.027 n Corresponding authors. Tel.: þ82 62 715 2292. E-mail addresses: vijayjiin2006@yahoo.com (V. Singh), jho@gist.ac.kr (Y.-D. Jho). Journal of Luminescence 132 (2012) 2036–2042