Spectroscopic and magnetic properties of neodymium doped in GdPO₄ sub-micron-stars prepared by solvothermal method

Neodymium-doped gadolinium orthophosphate (GdPO₄:Nd³⁺) luminomagnetic sub-micron-stars were prepared by solvothermal method using metal nitrates and phosphoric acid. Monoclinic star shaped in six lobed sub-micron-stars with 600 nm length is obtained with uniform particle size distribution. After heat-treatment at 800°C for 1 h in air, the stars separate into isolated petal shaped particles and show characteristic emission bands of Nd³⁺ with the strongest emission at 1064 nm. The emission intensities and fluorescence decay times are dependent on the Nd³⁺ concentration with the highest emission intensity and longest fluorescence decay time of 311 μs at 1064 nm with 0.5 mol% Nd³⁺. Under 808 nm excitation with 12 W/cm² power density a quantum yield of 9% was obtained for the 1.0 mol% Nd³⁺. The presence of paramagnetic Gd³⁺ gives magnetic properties to the phosphor with a calculated magnetic moment of 1510 and 107,965 Bohr magneton at 300 and 5 K, respectively.