NiWO4 powders prepared via polymeric precursor method for application as ceramic luminescent pigments

Abstract

NiWO 4 was prepared using the polymeric precursor method and studied in terms of physical and chemical properties to verify its stability for industrial applications as pigments. The characterization was accomplished using thermal analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and UV-Vis spectroscopies, colorimetric coordinates, and Raman spectra. Increasing the temperature, successive exothermic reactions were observed and they are related with thermal decomposition of the organic compound. The stability was reached at ~700 ℃. The material is verified to become completely free of second phase at ~800 ℃. The end NiWO 4 powders showed an intense charge transfer (CT)-related tail centered in the ultraviolet region, resulting in a yellow product. In addition, the powders exhibited broad excitation band and broad deep blue-green emission band, which were enhanced with increasing powders' crystallinity.

Effect of the Anionic Counterpart: Molybdate vs. Tungstate in Energy Storage for Pseudo-Capacitor Applications

“…The band at 899 cm −1 is assigned with the symmetric W=O stretching of the WO6 lattice and is in agreement with previous results [23]. The mode at 373 cm −1 is assigned to the symmetric vibration of NiO6 octahedra [27]. The bands at 809 and 690 cm −1 correspond to the bridging W-O-W stretching and the signal at 215 cm −1 to the bending W-O-W mode [23,26,28].…”

CeO2 and CeO2:Pr nanocrystalline powders prepared by the polymeric precursor method: Yellow and red pigments with tunable color

“…These parameters as a function of the annealing temperature are shown in Figure 7. As a result, the sample annealed at 800°C shows a white coloration with a total color difference (ΔE*) equals 13.75 compared to CeO 2 ‐400 sample, which is considered very large 48 . With Pr‐doping for the as‐prepared sample, a red‐orange coloration was observed.…”

Effect of anionic group [SiO4]4−/[PO4]3− on the luminescence properties of Dy3+-doped tungstate structural compounds

“…As the temperature increased, the luminescence intensity gradually decreased and thermal quenching occurred. The changes in the luminescence intensity of the three phosphors differed from each other, indicating that the thermal stability of tungsten fluorescent materials could be significantly influenced by the substitution of anions [33]. When the temperature increased to 150 ℃, the luminescence intensity of the Dy 3+ ions in the obtained Li 2 Ca(WO 4 ) 2 :0.08Dy 3+ , Li 2 Ca 2 (WO 4 )(SiO 4 ):0.08Dy 3+ , and LiCa 2 (WO 4 )(PO 4 ):0.08Dy 3+ samples were 79.85%, 75.85%, and 87.8% of their corresponding original values, respectively, indicating that they all had relatively high thermal stability.…”