Abstract
Er3+/Yb3+ co-doped SrAl2O4 (SRA: Er3+, Yb3+) phosphor has been synthesized by high temperature solid state reaction technique. The pure phase formation has been confirmed by X-ray diffraction (XRD) measurements. The surface morphology is studied by scanning electron microscopy (SEM) technique. The FTIR measurements give the information of vibrational bands arising due to sample. The intense UC emission from SRA: Er3+, Yb3+ phosphor has been monitored on excitation with 980 nm diode laser. The SRA: Er3+, Yb3+ samples prepared at 1473 K show a dominant green emission. On the other hand it shows dominant red emission when the sample is heated to 1623 K. Variation of concentration of Er3+ and Yb3+ ions in SRA: Er3+, Yb3+ phosphor suggests two possible mechanisms involved in UC emission process viz. cross relaxation (CR) process and energy back transfer (EBT) process, respectively. The cross relaxation mechanism seems to play a major role. The UC emission efficiency is enhanced several times on co-doping of Zn2+ ion replacing Al3+ or Sr+ in SRA: Er3+, Yb3+ phosphor sample. The color of the UC emission can be tuned from green to red region by varying the concentration of zinc. (C) 2017 Elsevier B.V. All rights reserved.