Influence of the thermal treatment in the crystallization of NiWO4 and ZnWO4

• Published in: Journal of thermal analysis and calorimetry Vol. 97; no. 1; pp. 167 - 172
• Main Authors: de Oliveira, A. L. M., Ferreira, J. M., Silva, Márcia R. S., de Souza, Soraia C., Vieira, F. T. G., Longo, E., Souza, A. G., Santos, Iêda M. G.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Dordrecht Springer Netherlands 01.07.2009; Springer
• Subjects: Analytical Chemistry; Calcination; Calorimetry; Carbon; Chemistry; Chemistry and Materials Science; Crystallization; Exact sciences and technology; Inorganic Chemistry; Inorganic chemistry and origins of life; Measurement Science and Instrumentation; Nickel; Physical Chemistry; Polymer Sciences; Precursors; Preparations and properties; Salts; Thermal analysis; Zinc; Wolframite; Order–disorder; ZnWO; NiWO; Thermal treatment; Heat treatment; Crystallization; Thermogravimetry; Order-disorder; Order disorder; X ray diffraction; Zinc Tungstates; Thermal analysis; Nickel Tungstates; Ultraviolet visible spectrometry
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-009-0244-8

NiWO 4 and ZnWO 4 were synthesized by the polymeric precursor method at low temperatures with zinc or nickel carbonate as secondary phase. The materials were characterized by thermal analysis (TG/DTA), infrared spectroscopy, UV–Vis spectroscopy and X-ray diffraction. NiWO 4 was crystalline after calcination at 350 °C/12 h while ZnWO 4 only crystallized after calcination at 400 °C for 2 h. Thermal decomposition of the powder precursor of NiWO 4 heat treated for 12 h had one exothermic transition, while the precursor heat treated for 24 h had one more step between 600 and 800 °C with a small mass gain. Powder precursor of ZnWO 4 presented three exothermic transitions, with peak temperatures and mass losses higher than NiWO 4 has indicating that nickel made carbon elimination easier.