Comparison of synthesis techniques for La2Zr2O7:Bi,Tb phosphor

Abstract

• Pyrochlore La 2 Zr 2 O 7 with Bi 3+ or Bi 3+ /Tb 3+ synthesized by four different techniques. • Comparative structural, morphological and optical properties reported in detail. • Cost, synthesis time, equipment and chemical yield are compared relatively. • Combustion/Microwave hydrothermal exhibited maximum PL for doped/codoped samples. • Microwave hydrothermal codoping gave best Tb 3+ emission at 542 nm excited at 310 nm. Combustion, co-precipitation, microwave-assisted hydrothermal synthesis and the polyol method were used to fabricate La 2 Zr 2 O 7 :Bi,Tb phosphor and evaluate its structural and optical properties. X-ray powder diffraction analysis confirmed the pyrochlore structure, although impurity phases were present in material synthesized by the polyol method. Scanning electron microscopy revealed similar microstructures for all synthesis methods, with particles of approximately 120 nm. However, the crystallite size varied significantly, from 24 nm for the co-precipitation method to 64 nm for the microwave hydrothermal method. The Bi-doped samples exhibited blue luminescence at 464 nm when excited with UV light, while the Tb-doped samples displayed green luminescence at 542 nm. The Bi-Tb co-doped samples showed green luminescence at 542 nm, resulting from energy transfer between Bi 3+ and Tb 3+ ions. Based on the ease, time and cost of synthesis, along with the analysis of structural and optical properties, the combustion method was determined as most suitable synthesis method. Photoluminescence Emission spectra excited at λ ex = 310 nm for Bi-Tb co-doped La 2 Zr 2 O 7 samples prepared by four synthesis techniques and corresponding schematic energy transfer process.