Nano-size effects on the nature of bonding in Y2Sn2O7: EXAFS and Raman spectroscopic investigations

Nature of bonding around Y3+ and Sn4+ ions in Y2Sn2O7 phase, both in the bulk and in nanosize dimensions, were investigated by yttrium K edge EXAFS measurement, Raman spectroscopy and theoretical calculations based on density functional theory (DFT). From the investigations it is established that Y–O bond is more covalent in nanoparticles of Y2Sn2O7, compared to bulk Y2Sn2O7. Asymmetric electron density distribution around Sn4+ in nanoparticles of Y2Sn2O7, compared to bulk, leads to the improvement in the Raman activities of bending and stretching vibrational modes of Y–O, Y–O–Sn and Sn–O linkages.