Enhanced photoluminescence of CoWO4 in CoWO4/PbWO4 nanocomposites

CoWO4/PbWO4 nanocomposites were successfully synthesized at room temperature (RT) by co-precipitation route without using any templates or surfactants and sintered at 600 A degrees C for good crystallization. The sintered samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy and Zeta potential measurements. UV-Visible diffuse reflectance spectroscopy, photoluminescence (PL) and PL lifetime were studied at RT. The results indicate that the composites have two-phase composition: CoWO4 and PbWO4. SEM micrograph and zeta potential measurements reveal particle agglomeration. The intrinsic PL peak emission at 467 nm of CoWO4 nano sample was enhanced upto four times by optimizing the atomic ratio of Pb/Co concentration. The interconnected interface of CoWO4/PbWO4 nanocomposites could have led to increase in number of recombination of electron hole pairs in CoWO4 and enhanced its intrinsic PL emission intensity. The mechanism of enhanced PL emission for the CoWO4/PbWO4 nanocomposites can be attributed to charge transfer between [WO4](2-) and [WO6](6-) complexes due to intra particle agglomeration leading to possible interface.