Bull. Mater. Sci., Vol. 40, No. 7, December 2017, pp. 1347–1354 © Indian Academy of Sciences https://doi.org/10.1007/s12034-017-1485-y Synthesis and luminescence in sol–gel auto-combustion-synthesized CaSnO 3 :Eu 3+ phosphor MOGES TSEGA 1,* and FRANCIS BIRHANU DEJENE 2 1 Department of Physics, Bahir Dar University, Bahir Dar 3019, Ethiopia 2 Department of Physics, University of the Free State, QwaQwa Campus, Private Bag X13, Phuthaditjhaba 9866, South Africa ∗ Author for correspondence (mogestsega@yahoo.com) MS received 14 November 2016; accepted 21 February 2017; published online 14 November 2017 Abstract. Undoped and Eu-doped CaSnO 3 nanopowders were prepared by a facile sol–gel auto-combustion method calcined at 800 ◦ C for 1 h. The samples are found to be well-crystallized pure orthorhombic CaSnO 3 structure. Photolumi- nescence (PL) measurements indicated that the undoped sample exhibits a broad blue emission at about 420–440 nm, which can be recognized from an intrinsic centre or centres in CaSnO 3 . Eu-doped CaSnO 3 showed broad blue emission centred about 434 nm, a weak peak at 465 nm and a sharp intense yellow emission line at 592 nm. The emission situated at 592 nm was assigned to the f–f transition of 5 D 0 → 7 F 1 in Eu 3+ ions. The afterglow emission and PL decay results in Eu-doped CaSnO 3 phosphor, which revealed that there are at least two different traps in this phosphor. From the obtained results, Eu 3+ -doped CaSnO 3 phosphor could be proposed as a potential white luminescent optical material. Keywords. CaSnO 3 ; sol–gel preparation; doping; luminescence. 1. Introduction Perovskite-type calcium stannate (CaSnO 3 ) has received increasing attention due to its wide applications in ceramic dielectric bodies, gas and humidity sensors [1], anode mate- rials for lithium ion batteries [2,3], photocatalysts [4], etc. As reported, only two phases of CaSnO 3 and Ca 2 SnO 4 exist in the CaO-SnO 2 binary system. CaSnO 3 , with orthorhom- bic perovskite structure, is composed of octahedral SnO 6 , which connect to each other by sharing vertexes. Further- more, the structure of Ca 2 SnO 4 , which consists of SnO 6 octahedral that are linked by edges and seven oxygen ions surrounding Ca 2+ , exhibits an arrangement with low symmetry [5]. Recently, luminescence properties of rare-earth-cation- doped perovskite-type compounds have received consider- able attention due to their abundant emission colours based on their 4f–4f or 5d–4f transitions [6]. It is well known that luminescence measurements are very sensitive to monitor variations in the chemical and structural local environment of respective luminescent ions and thus, have the potential to probe distortions of fluorescence sites. The lumines- cence properties of rare-earth-doped stannite crystal were reported for CaSnO 3 :Sm 3+ , Nd 3+ , Er 3+ [7], CaSnO 3 :Eu 3+ [8], CaSnO 3 :Er 3+ , Tm 3+ , Yb 3+ [9], CaSnO 3 :Pr 3+ [10], Ca 2 SnO 4 :Tb 3+ [11] and M 2 SnO 4 :Sm 3+ (M = Ca, Sr and Ba) [12]. Of the many rare-earth ions, Eu 3+ ion is well known as an important activator for many different inorganic lattices producing red, green and reddish-orange light emissions [13–15]. To the best of our knowledge, the blue–yellow- emitting CaSnO 3 :Eu 3+ phosphor is not reported yet. Many synthesis routes have been worked out to prepare CaSnO 3 , such as chemical coprecipitation [16], hydrother- mal method [9], sol–gel [8,17], solid-state reaction [10,18], etc. Although many papers on various kinds of synthesis were published, synthesis of CaSnO 3 through a sol–gel auto- combustion method is not studied extensively. It is well known that the properties of materials are related to the preparation method. In the attempt to avoid high tempera- ture treatments and the consequent possible lack of chemical and dimensional homogeneity, the sol–gel route has become an appropriate method for the preparation of nanocrys- talline materials. The benefits for preparing CaSnO 3 by the sol–gel auto-combustion method include the synthesis of nanosized crystalline powder with high purity at a relatively low temperature, possibility of stoichiometry-controlling process and production of homogeneous materials. In this work, we have investigated the structural, photoluminescence (PL) and thermoluminescence (TL) properties of undoped and Eu 3+ -doped CaSnO 3 nanopowders prepared by sol–gel auto-combustion method. Our luminescence results show that the rare-earth-doped CaSnO 3 has remarkable potential for applications as an optical material in the visible emission range. 1347