SPECTROSCOPIC AND MAGNETIC PROPERTIES OF NEODYMIUM DOPED IN GDPO4 NANOSTARS PREPARED BY SOLVOTHERMAL METHOD
Nicolas Balli, Ajith Kumar, Dhiraj Sardar.
The University of Texas at San Antonio, San Antonio, TX.
Neodymium-doped gadolinium orthophosphate (GdPO4:Nd3+) luminomagnetic nanostars were prepared by a solvothermal method using metal nitrates and phosphoric acid. Monoclinic 6-lobed nanostars with 600 nm length were obtained with uniform particle size distribution. After heat-treatment at 800 °C for 1 hour in air, the GdPO4:Nd3+ sample showed characteristic emission bands of Nd3+ with the strongest emission at 1,064 nm. The emission intensity and fluorescence decay time are dependent upon the Nd3+ concentration with the highest emission intensity and longest fluorescence decay lifetime of 311 µs at 1,064 nm with 0.5 mol% Nd3+. Under 808 nm excitation with 12 W/cm2 power density, we obtained a quantum yield of 9% for the 1.0 mol% Nd3+. The presence of paramagnetic Gd3+ exhibits magnetic properties, giving the nanostars a calculated magnetic moment of 1,510 and 107,965 Bohr magneton at 300 K and 5 K, respectively.