Preparation and characterization of Ln2Zr2O7 (Ln = La and Nd) nanocrystals and their photocatalytic properties

Two lanthanide zirconates Ln2Zr2O7 (Ln = La and Nd) with pyrochlore structures were prepared by solid-state reaction at a relatively low temperature. The as-prepared Ln2Zr2O7 nanocrystals were characterized by XRD, FT-IR, TEM, HRTEM, EDS and BET. The as-obtained nanocrystals were composed of square-like particles with the average size of 20-50 nm. The interplanar distances of d222 and d440 measured from the HRTEM images for La2Zr2O7 nanocrystals were 0.303 nm and 0.185 nm, respectively, coinciding with the theoretical values. The interplanar distance of d222 for Nd2Zr2O7 was 0.307 nm. The La2Zr2O7 and Nd2Zr2O7 nanocrystals gave a relatively high value in surface area of 11.33 m2/g and 3.48 m2/g, respectively. Moreover, the photocatalytic activity was measured and the photodegraded amount of methyl orange catalyzed by La2Zr2O7 nanocrystals in 1 h was bigger than that of Nd2Zr2O7 nanocrystals.