Preparation, characterization, photocatalytic activity and conductivity of BiLnZr2O7 (Ln = La, Sm, Eu and Gd)

Bismuth containing pyrochlore type oxides (BiLnZr2O7; Ln = La, Sm, Eu and Gd) were prepared by sol–gel method. The obtained compositions were characterized by powder X-ray diffraction (PXRD), Thermal analysis (DTA–TG), Raman spectroscopy, Energy dispersive spectroscopy (EDS) and UV–Vis diffuse reflectance spectroscopy (DRS). Both BiSmZr2O7 and BiEuZr2O7 are unstable above 700 °C unlike BiLaZr2O7 and BiGdZr2O7. All the samples show good photocatalytic activity under visible light irradiation in presence of H2O2. The DC conductivity of all these materials was carried out in the temperature range 130–700 °C and a detailed explanation for the observed changes is given. -- Highlights: ► BiLnZr2O7 (Ln = La, Sm, Eu, Gd) were prepared by sol–gel method. ► BiLnZr2O7 (Ln = Sm, Eu) are unstable above 700 °C. ► These pyrochlores show good photoactivity in the presence of H2O2.