Abstract

A selective method was proposed to produce single-phase powders of tungsten(VI) oxide γ-WO₃ (monoclinic system) and h-WO₃ (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-WO₃ 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-WO₃. For the first time, estimation was made of the sun protection factor SPF and UV-A protection factor UVAPF of the γ-WO₃ and h-WO₃ powders according to a standardized measurement procedure (GOST ISO 24443-2016).

中文翻译：

---

柠檬酸存在下γ-WO3和h-WO3粉末的水热合成及其光保护性能

摘要

提出了一种通过水热处理（180-220°C）B-仲钨酸铵制备钨（VI）氧化物γ-WO ₃（单斜晶系）和h - WO ₃ （六方晶系）单相粉末的方法。柠檬酸（钨与柠檬酸的摩尔比为 1 : 1 或 1 : 2.5）在 pH 值范围 0.5–2.5 中存在。反应混合物的 pH 起始值对合成产物的相组成有关键影响：单相 γ-WO ₃粉末可以在 180-220°C 和 pH 0.5-1.0 的温度下形成，并且增加在 pH 值为 2.0-2.5 时有利于形成h -WO ₃. 首次根据标准化测量程序 (GOST ISO 24443-2016)估算了 γ-WO ₃和h -WO ₃粉末的防晒系数 SPF 和 UV-A 保护系数 UVAPF 。