Effect of variable trivalent europium concentration on photo- and thermoluminescence of zirconium dioxide nanophosphors

Abstract

The present paper reports synthesis and characterization of trivalent europium (Eu3+) doped zirconium dioxide (ZrO2) nanophosphors. Effect of variable concentrations of europium on photoluminescence (PL) and thermoluminescence (TL) behavior is also studied. Samples were prepared by the combustion synthesis technique which is suitable for less time taking techniques and also for large scale production of nanophosphors. Starting materials used for sample preparation are Zr(NO3)3 and Eu(NO3)3 and urea is used as a fuel. The prepared sample was characterized by an X-ray diffraction technique (XRD) with variable concentrations of Eu3+ (0.5–2.5mol%). There was no phase change found with increase in the concentration of Eu3+. Sample shows monoclinic structure and the crystallite sizes were calculated by Scherer׳s formula. The surface morphology of prepared phosphor was determined by a field emission gun scanning electron microscopy technique. Good connectivity with grains and the sphere line structure was found by FEGSEM. Functional group analysis was determined by Fourier transform infrared spectroscopic techniques. All prepared phosphors with variable concentrations of Eu3+ (0.5–2.5mol%) were studied by photoluminescence analysis and it was found that the excitation spectra of prepared phosphor showed sharp excitation peak centered at 295nm. The emission spectra with variable concentrations of Eu3+ show strong peaks at 594nm and 612nm range with dominant peak at 612nm due to the allowed electronic transition 5D0→7F2 and weaker transition at 594nm which was due to magnetic dipole transition 5D0→7F1. Spectrophotometric determinations of peaks are evaluated by the Commission Internationale de I׳Eclairage technique. The prepared phosphor was also examined by the thermoluminescence technique. For recording TL glow curve, every time 2mg phosphor was irradiated by UV 254nm source, with a fixed heating rate at 6.7°Cs−1. Sample showed well resolved peak at 170°C for 2mol% of Eu3+. Also the effect of Eu3+ concentration at fixed UV exposure time was studied. Effect of UV exposure time and dose versus intensity plot were studied. The sample shows linear response with dose and broaden peak with high temperature shows more stability and less fading in TL glow curve. The linear dose response, high stability and less fading phenomenon show that the sample may be useful for thermoluminescence dosimetry application. Trapping parameters were also calculated for each recorded glow curve.