对铝酸钇而言,有害杂质有 K、Na、Ca、Mg、Si 和 Fe 等,采用尿素均相沉淀法提纯 Y_2O_3 时,钾、钠、钙和镁的分离效果较好,而铁和硅的分离效果却很差。二价铁是荧光猝灭剂,它对激光性能是十分有害的,硅的存在使晶体不透明甚至开裂,因此,必须预先将它们除去。氧化钇溶于 HNO_3后,铁以高铁离子存在溶液中;当溶液 pH 在6至6.9时,铁以 Fe(OH)_3胶体存在溶液中,此时若加入适量尿素并加热溶液,则少量的 Y(OH)_3就形成,它可作载体将 Fe(OH)_3胶体带到沉淀中,分离后铁的含量(以Y_2O_3计)可降至 ppm 量级。当需进一步降低 In the case of yttrium aluminate, K, Na, Ca, Mg, Si, and Fe are the noxious impurities. When Y_2O_3 is purified by urea homogenization, potassium, sodium, calcium and magnesium are separated well, while iron and silicon The separation effect is poor. Ferrous iron is a fluorescent quencher, which is very detrimental to laser performance. The presence of silicon makes the crystals opaque or even cracked, and therefore they must be removed beforehand. When Yttrium oxide is dissolved in HNO_3, iron is present in solution as high iron ions. When the solution pH is in the range of 6 to 6.9, Fe is present in the solution as Fe (OH) _3 colloid. At this time, if a proper amount of urea is added and the solution is heated, a small amount of Y (OH) 3, which can be used as a carrier to carry Fe (OH) 3 colloid to the precipitate. After separation, the content of iron (calculated as Y_2O_3) can be reduced to the order of ppm. When needed to further reduce