Hydrothermal Synthesis of γ-WO3 and h-WO3 Powders in the Presence of Citric Acid and Their Photoprotective Properties

• Published in: Russian journal of inorganic chemistry 2022-06, Vol.67 (6), p.780-789
• Main Authors: Filippova, A. D., Rumyantsev, A. A., Baranchikov, A. E., Kolesnik, I. V., Ivanova, O. S., Efimov, N. N., Khoroshilov, A. V., Ivanov, V. K.
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Citric acid; Hydrothermal treatment; Inorganic Chemistry; Phase composition; Synthesis; Synthesis and Properties of Inorganic Compounds; Tungsten oxides
• ISSN: 0036-0236; 1531-8613
• DOI: 10.1134/S0036023622060080

A selective method was proposed to produce single-phase powders of tungsten(VI) oxide γ-WO 3 (monoclinic system) and h -WO 3 (hexagonal system) by hydrothermal treatment (180–220°C) of ammonium B-paratungstate in the presence of citric acid (in a molar ratio of tungsten to citric acid of 1 : 1 or 1 : 2.5) in the pH range 0.5–2.5. The starting value of the pH of the reaction mixtures has a key effect on the phase composition of the synthesis products: single-phase γ-WO 3 powders can form at temperatures of 180–220°C at pH 0.5–1.0, and an increase in pH to 2.0–2.5 favors the formation of h -WO 3 . For the first time, estimation was made of the sun protection factor SPF and UV-A protection factor UVAPF of the γ-WO 3 and h -WO 3 powders according to a standardized measurement procedure (GOST ISO 24443-2016).