Preparation, characterization, emission (Eu3+), and electron spin resonance (Gd3+) studies of Y2-xLnxTi2O7 (Ln=Eu and Gd, x=0.0,0.05)

Bulk and nanopyrochlore materials of composition Y(2-x)Ln(x)Ti(2)O(7) (Ln=Eu and Gd, x=0.0,0.05) have been prepared by sol-gel method via peroxo titanium complex precursor. All the samples were characterized by powder x-ray diffraction (XRD), Raman spectra, and transmission electron microscopy (TEM). The unit cell parameters were obtained from Rietveld analysis of XRD patterns. The influence of particle size on the emission of Eu3+ (in Y2-xEuxTi2O7), the electron spin resonance (ESR) of Gd3+ (in Y2-xGdxTi2O7) and optical absorption spectra have been studied. The band gap energy of Y(1.95)Ln(0.05)Ti(2)O(7) (Ln=Eu and Gd) was determined and compared with parent Y2Ti2O7. The variation in the emission intensity of Eu3+ is accounted with the particle size and short range order. The spin-Hamiltonian parameters of Gd3+ were obtained from the powder ESR spectra. The single-ion anisotropy was taken in to account in the analysis of powder ESR spectra. The crystallite size was obtained from powder XRD and TEM images. (C) 2010 American Institute of Physics. [doi:10.1063/1.3476057]