Heat treatment temperature effect on the microstructure and optical properties of Dy2(WO4)3 powders

Dy₂(WO₄)₃ powders were synthesized through liquid-phase reaction. The structure transformation of Dy₂(WO₄)₃ powders were analyzed by differential scanning calorimetry (DSC), X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR). The optical absorption and photoluminescence properties were characterized by UV-vis-infra diffuse reflectance spectra and fluorescence spectra. The Dy₂(WO₄)₃ host could absorb deep UV light and transfer the energy of UV light to Dy³⁺ ions, which convert the high-energy UV light to blue light (482 nm, ⁴ F _9/2→⁶ H _15/2) and yellow light (547 nm, ⁴ F _9/2→⁶ H _13/2). The Dy₂(WO₄)₃ powders could also absorb near UV light and exhibit blue and yellow emissions near 482 and 547 nm, respectively. Heat treating promoted the crystallization and regulated the micro-structure of Dy₂(WO₄)₃ hosts. The bands of W-O_d anti-symmetric stretching vibration exhibited red shift with the increasing of sintering temperature. The W-O_b-W groups tended to combine with each other to form W-O_c-W groups after heat treating. These regulation of micro-structure had influence on the luminescent color of Dy₂(WO₄)₃. The samples could emit yellow-green, white-yellow and white light under the excitation of 350 nm after being treated at 600, 800 and 1 000 °C, respectively. The prepared Dy₂(WO₄)₃ powders have potential to act as UV absorber for solar cell to improve the conversion efficiency and also exhibit potential for white light LED.