Effect of Cu-doping on structural, optical and photoluminescence properties of zinc titanates synthesized by solid state reaction Budigi Lokesh 1 • N. Madhusudhana Rao 1 Received: 28 November 2015 / Accepted: 3 January 2016 Ó Springer Science+Business Media New York 2016 Abstract Undoped and Cu-doped zinc titanates were synthesized by solid-state reaction. The structural and phase transition properties were studied using powder XRD. The elemental composition of the samples was studied using EDAX analysis. Optical studies were carried by measuring photoluminescence and diffused reflectance. Bandgap energies were calculated using Tauc’s relation from the diffuse reflectance spectra. A decrease in lattice parameters, unit cell volume and bandgap energies were observed with Cu doping in zinc titanate. Photolumines- cence intensity at 386 nm in the violet region was enhanced on increasing Cu dopant concentration. 1 Introduction Solid state synthesis method is a relatively simple way to prepare metal oxide powders with good crystallinity at high temperatures. The doped and undoped zinc titanates were synthesized by solid state reaction by a number of researchers [1–4]. Zinc titanates exists in different phases like cubic defect spinel Zn 2 Ti 3 O 8 , cubic phase ZnTiO 3 , hexagonal ilmenite (IL) phase ZnTiO 3 , and cubic inverse spinel Zn 2 TiO 4 phases depending on the synthesis condi- tions. Recently LiNbO 3 type ZnTiO 3 , a metastable phase obtained by the transformation in the decompression pro- cess from the perovskite phase, which is stable at high temperature and high pressure was reported [5]. Zn 2 TiO 4 could be prepared readily by conventional solid state reaction using 2:1 mol ratio ZnO and TiO 2 , whereas ZnTiO 3 is difficult to obtain by solid state reaction using 1:1 mol ratio of ZnO and TiO 2 due to its narrow phase stability temperature region [6, 7]. In recent years a con- siderable amount of work has been devoted to probe the properties and phase transition characteristics of Zinc titantes by doping with appropriate cations like Mg 2? , Sr 2? , Co 2? , Pb 2? , Ni 2? , Mn 2? etc., [8–11]. It is reported that doping ZnTiO 3 with above mentioned ions at Zn 2? site was effective in stabilizing hexagonal ilmenite ZnTiO 3 by increasing its decomposition temperature [12–18]. Doping of Cu 2? , Sr 2? , Pb 2? , La 3? or Eu 3? at Zn 2? site, or W 6? at Ti 4? site were reported to be effective in promoting cubic Zn 2 TiO 4 phase formation by reducing the decomposition temperature of ZnTiO 3 phases [19–21]. It is interesting to note that the dopants forming MTiO 3 type ternary oxides, where M is Mg 2? , Mn 2? , Co 2? , Ni 2? or Cd 2? having stable IL-type structures are effective in increasing the stability of IL-phase ZnTiO 3 by increasing its decomposi- tion temperature. Similarly cations like Cu 2? , Sr 2? , Pb 2? , La 3? , Eu 3? etc. forming cubic phase ternary oxides with Ti 3? /Ti 4? are effective in forming stable cubic phase zinc titanates. It is reported that doping small amount ( \ 1.00 wt%) of W 6? at Ti 4? site accelerated the decom- position of IL-pahse ZnTiO 3 and formation of cubic phase Zn 2 TiO 4 , while excessive doping ( [ 3.00 wt%) restrained the decomposition [22, 23]. Dopants like Mg 2? , Co 2? , Ni 2? , Cd 2? enhanced the stability of IL-phases and improved the microwave dielectric properties of ZnTiO 3 significantly. In spite of this phase transformation of zinc titanates, authors wish to make a serious attempt to study the effect of transition metal ion doping in phase transition of zinc titanate. In the present study, we report the syn- thesis and characterization of undoped, 0.1 and 0.2 mol Cu doped Zinc titantes by solid state reaction to study the & N. Madhusudhana Rao drnmrao@gmail.com 1 Thin Films Laboratory, Centre for Crystal Growth, VIT University, Vellore, Tamil Nadu 632014, India 123 J Mater Sci: Mater Electron DOI 10.1007/s10854-016-4290-2