Optical and structural properties of Nd doped SnO2 powder fabricated by the sol–gel method

Abstract

We report on the structural and optical properties of undoped and neodymium doped SnO₂ powders (0, 1, 3, and 5 at% of Nd) synthesized by the sol–gel method. SEM and TEM microscopy techniques reveal a nanometric scale of the powders. We show that the tetragonal rutile phase is achieved after annealing at 700 °C. The crystallite size of the doped SnO₂ is found to decrease gradually with the increase of Nd content without changing the SnO₂ structure. A strong decrease in the intensity of the Raman peaks is noted for doped powders, which can be attributed to the location of Nd³⁺ ions at the Sn sites indicating Nd incorporation into the host matrix. For the first time the optical properties were studied by UV-Vis-NIR spectroscopy and revealed Nd related absorption bands in the SnO₂ matrix. The investigation of the photoluminescence properties shows broad emission centred around 550–650 nm originating from defects present in the SnO₂ host matrix. Under 325 nm laser excitation, a strong photoluminescence of trivalent Nd is observed in the infrared region and shows Nd related emission peaks at 885, 1065, and 1336 nm. Such a strong PL signal under laser excitation indicates that Nd³⁺ is optically active. The excitation dependent PL (PLE) recorded in the 450–700 nm range confirms the presence of active Nd³⁺ successfully inserted into the SnO₂ host matrix.