Synthesis and photoluminescence properties of Tb 3+ -doped Sr 0.5 Zn 0.5 Al 2 O 4 nanocrystal phosphor prepared via combustion process S.K K. Shaat 1 , F. Roelofse 2 , H.C. Swart 1 and O.M. Ntwaeaborwa 1,3 Department of Physics, University of the Free State, P. O. Box 339, Bloemfontein, ZA9300, South Africa Department of Geology, University of the Free State, P.O. Box 339, Bloemfontein, ZA9300, South Africa 3 Corresponding author: ntwaeab@ufs.ac.za or samyshaat@yahoo.com Abstract. Tb 3+ doped Zn 0.5 Sr 0.5 Al 2 O 4 (ZSAO) nanocrystalline phosphor was successfully synthesized by a combustion method at a relatively low temperature (500 o C), using metal nitrates as precursors and urea as a fuel. The samples were annealed in air at 700 o C for 4 hrs. The X-ray diffraction patterns showed phases associated with both ZnAl 2 O 4 (ZAO) and SrAl 2 O 4 ( SAO) as referenced to standard JCPDS data files No. 05-0669 and 74-794, respectively. As confirmed from the scanning electron microscopy images, the characteristic platelet-like particles of the combustion method were formed. The photoluminescence emission and excitation spectra of Zn 0.5 Sr 0.5 Al 2 O 4 :Tb 3+ before and after annealing were recorded and compared to those of ZnAl 2 O 4 :Tb 3+ and SrAl 2 O 4 :Tb 3+ . In all cases, PL emissions were due to 5 D 4 → 7 F J (J = 0,1,2,3,4,5,6) transitions of Tb 3+ . The PL emissions of ZnAl 2 O 4 :Tb 3+ and SrAl 2 O 4 :Tb 3+ were more intense than that of Zn 0.5 Sr 0.5 Al 2 O 4 :Tb 3+ . The objective of the study was to prepare a new aluminate host for Tb 3+ consisting of Zn and Sr and evaluate its luminescent properties and chemical study for application in lighting. 1. Introduction In recent years, interests have been focused on the development of new luminescent materials (phosphors) such as lanthanide-doped nanomaterials. Among the known luminescent materials, lanthanide (Ln) ions doped inorganic materials offer a range of compounds with unique versatility. In particular, oxide matrices are attractive host materials for the study of development of advanced phosphors due to their ease of synthesis and chemical stability [1]. Among various host oxide matrix materials, aluminates are considered to possess high energy efficiency, wide excitation wavelength range, and high quenching temperature. Aluminium-based spinels are an intriguing class of oxide ceramics with important technological applications. Rare earth ions (RE) doped aluminates serve as an important class of phosphor for fluorescent lamp and plasma display application and phosphorescence. As one of the most promising phosphors, strontium aluminate spinel, SrAl 2 O 4 (SAO), has been found 3 Corresponding author: email address: ntwaeab@ufs.ac.za