Preparation, Characterization, Photocatalytic Activity and Conductivity Studies of YLnTi₂O₇ (Ln = Nd, Sm, Eu and Gd)

Abstract

Bulk and nano sized oxides belonging to pyrochlore family of composition YLnTi₂O₇ (Ln = Nd, Sm, Eu and Gd) have been prepared by sol-gel method. The as-prepared gel ‘precursor’ was sintered at different temperatures in the range 675°-900°C. All the materials were characterized by TGA-DTA, powder XRD, Raman, EDS, XPS and UV-Visible diffuse reflectance spectra. The crystallization of all the materials got started around 700°C. All these oxides were crystallized in ordered pyrochlore lattice with Fd3m space group. The average crystallite size calculated from the FWHM of intense XRD line was in the range 25-50 nm. The vibrational modes observed from Raman spectroscopy also support ordered pyrochlore structure for these oxides. The photocatalytic activities of all the nano powders were evaluated by photodegradation of methylene blue under visible light irradiation. The DC conductivity of all these materials was carried out in the temperature range 180°-560°C and discussed.

Keywords:

• Sol-gel
• X-ray diffraction
• Raman spectroscopy
• Optical properties
• Electrical conductivity