Synthesis of green emission upconversion phosphor nanosheets (LaNb2O7) doped with Er3+ and Yb3+

LaNb2O7:Er3+,Yb3+ upconversion (UPC) phosphor nanosheets were prepared by exfoliating a KLaNb2O7:Er3+,Yb3+ layered compound. Highly crystalline nanosheets with a thickness and lateral size of 3.91 nm and approximately 300 nm, respectively, were obtained. The UPC emission intensity of the nanosheets was 7.6 times greater than that of mechanically milled particles (100-500 nm) of bulk KLaNb2O7:Er3+,Yb3+. The UPC emission intensities of the nanosheets dispersed in different solvents (H2O, D2O, CH3OH, CH2Cl2, and CCl4) were measured, and the intensities were observed to decrease in the order CCl4>CH2Cl2>D2O>CH3OH>H2O. Because of the large surface area of the nanosheets, their emission intensity was decreased depending on the solvent׳s vibrational energy.