Abstract

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Bismuth and cobalt co-doped perovskite-type nanomaterials with the composition Nd0.5Bi0.2(Co0.3Mn0.1)FeO3-δ were syn thesized by using the citric acid sol-gel route and annealed at annealing temperatures (TA) of 400, 750 and 900°C to pro duce powders labelled NdCo400, NdCo750 and NdCo900 respectively. The powders obtained were characterized using Powder X-ray diffraction (PXRD) analysis, transmission electron microscopy (TEM), Fourier transform infrared spectros copy (FTIR), Braunuer-Emmet-Teller (BET) Method, vibrating sample magnetometer, (VSM) and photoluminescence spectroscopy (PL). The powder X-ray diffraction (PXRD) analysis of the powders showed that they contain highly crystal line orthorhombic perovskite-type nanoparticles whose crystallinity increased with higher annealing temperature. The lat tice parameters, after refinement for NdCo900, showed that the parameters a, b and c have values 5.939, 5.488 and 7.740 Å respectively. The TEM results showed cubic crystallites with average crystalline size within the range of 17-30 nm for both NdCo750 and NdCo900 respectively. The BET specific surface areas obtained was 12.46 and 5.92 m2 g-1 for NdCo750 and NdCo900. Room temperature VSM analysis showed TA dependent properties for the powders NdCo400 (11.09 emu g-1, 402 Oe), NdCo750 (9.00 emu g-1, 2181 Oe) and NdCo900 (9.44 emu g-1, 683.16 Oe) for saturation mag netization MS and coercive field HC values respectively. Photoluminescence spectroscopy showed that the powders were all active in the visible region and could be useful for visible light photodegradation of organic dyes. NdCo900 was the most effective for the decolourization of RhB dye with kobs = 1.6 × 10-2 min‑1 and percent efficiency E % = 99.1 %. A 73 % mineralization of the dye was also achieved after 3 h

Keywords: Perovskites, Coercive field, Photoluminescence, Photocatalytic activities.