Er3+-Yb3+-Na+:ZnWO4 phosphors for enhanced visible upconversion and temperature sensing applications

The crystal structure and surface morphology of the Er3+/Yb3+/Na+:ZnWO4 phosphors synthesized by solid state reaction method were analyzed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis. The frequency upconversion (UC) emission study in the developed phosphors was investigated by using 980 nm laser diode excitation. The effect of codoping in the Er3+:ZnWO4 phosphors on the UC emission intensity was studied. The UC emission bands that are exhibited in the blue (490 nm), green (530, 552 nm), red (668 nm) and NIR (800 nm) region correspond to the 4F7/2→4I15/2, 2H11/2, 4S3/2→4I15/2, 4F9/2→4I15/2 and 4I9/2→4I15/2 transitions, respectively. The temperature sensing performance of the Er3+-Yb3+-Na+:ZnWO4 phosphors was investigated based on the 2H11/2→4I15/2 and 4S3/2→4I15/2 thermally coupled transitions of the Er3+ ions. The photometric study was also carried out for the developed phosphors.