Paper Title
Effect of Synthetic Conditions on The Hexagonal Disk Form of Naluf4: Yb, Er, Gd Upconversion Material

Abstract
The uniform hexagonal disk-shaped of Gd3+,Yb3+,Er3+-codoped NaLuF4 upconversion material has been successfully prepared using hydrothermal route. The prepared samples possess good fluorescent emission under laser excitation at a wavelength of 980 nm. The effect of synthetic conditions, such as the precursor concentration, pH values, and temperature on the shape was detailed. The possible formation and upconversion mechanisms were proposed. This study is expected to provide information for controlled synthesis of other upconversion materials. Keywords� Hexagonal, Rare earth, Upconversion, Mechanism.