Dysprosium stannate (Dy2Sn2O7)-nanostructured thin films prepared by spray pyrolysis technique: effect of dysprosium and annealing on the physical properties

Abstract

In this paper, dysprosium stannate-nanostructured thin films (Dy2Sn2O7) were deposited by spray pyrolysis method on fused silica substrates at T = 480 °C. A solution of 0.1 molar tin(IV) chloride pentahydrate (SnCl4⋅5H2O) and dysprosium(III) nitrate with mole ratios of [Dy/Sn] % = 10, 30, 50, 70, and 100% was used to prepare dysprosium stannate-nanostructured thin films (Dy2Sn2O7) by spray pyrolysis method. Then, the effect of Dy-content and annealing temperature in air at T = 500, 600, 1100 and 1200 °C, on structural conversion and optical properties were investigated for these films. The X-ray diffraction (XRD) patterns indicated that the dominant phase above T = 1100 °C is pyrochlore phase of dysprosium stannate. The field emission scanning electron microscopy (FE-SEM) images showed the formation of nanocrystals of dysprosium stannate with pyrochlore structure. The FE-SEM images show that the surface morphologies of as-prepared films are in the form of cubic nanocrystals before annealing and nano-polyhedral as agglomerated after annealing at T = 1200 °C. The results of UV–Vis analysis indicated that with increasing the Dy-content and annealing at T = 1200 °C, optical transmittance and bandgap was increased. The optical bandgap for ratios of [Dy/Sn] = 50 and 100% were obtained 2.65 and 2.76 eV, respectively, after annealing at T = 1200 °C.