Luminescence and structural properties of ytterbium and erbium co-doped LaGaO3 nanophosphor for up-conversion by polyol method

Abstract Ytterbium and erbium co-doped lanthanum gallate (LaGaO3) up-conversion phosphors have been synthesized using polyol method followed by heating at 1000°C. From Fourier transform infrared (FTIR) spectroscopy and thermal analysis studies of as prepared sample, formation of hydroxy carbonate precursor has been confirmed. This precursor undergoes two step decomposition leading to the formation of LaGaO3 phase. Detailed X-ray diffraction studies confirmed the formation of orthorhombic LaGaO3 phase with distorted GaO6 octahedra and distorted LaO12 cuboctahedra. As the annealing temperature increased from 1000°C to 1200°C, green to red ratio (GRR) as well as lifetime values increased and this is explained based on the increase in crystallite size from 40 nm to 95 nm and associated decrease in the extent of quenching (non-radiative) processes. Variation in the “n” values accounts for the observed increase in the GRR values corresponding to 1000°C and 1200°C annealed samples with increase in laser power.