Sol-gel modified Pechini method for obtaining nanocrystalline KRE(WO4)2 (RE = Gd and Yb)

Abstract

KRE(WO4)2 (RE = Gd and Yb) nanocrystalline powder was obtained by the modified sol-gel Pechini method. The precursor powder was calcined between 923 and 1023 K for a maximum of 6 h at air atmosphere. DTA-TG of the precursor powder shows that the temperature for total calcination is around 800–850 K. Molar ratio between the complexing agent and the metal ions in the first step of the method and molar ratio between the complexing agent and the ethylene glycol in the second step of the method were studied to optimize the preparation process. X-ray diffraction and IR spectroscopy were used to study the transformation from precursor powder into a crystalline monoclinic phase. Raman spectroscopy was used to study the vibrational structure of the nanoparticles. The Scherrer formula was used to confirm the grain sizes visualized by SEM and TEM techniques. Small nanoparticles in the range of 20–50 nm of monoclinic KREW have been successfully obtained by this methodology.