四硼酸锶(SrB_4O_7)的制备新工艺及其影响因素

采用液相沉淀法合成两种水合硼酸锶SrB₂O₄ ?4H₂O和SrB₆O₁₀ ?5H₂O, 将其高温煅烧制备出纯四硼酸锶(SrB₄O₇)相, 分析了高温煅烧过程、产物的物相和形貌, 研究了煅烧温度和保温时间等因素的影响。结果表明, 在加热过程中水合硼酸锶发生脱水 → 非晶化→ 晶化过程, 且SrB₆O₁₀在800℃左右分解为SrB₄O₇和液态氧化硼; 将SrB₂O_4  ?4H₂O和SrB₆O_10 ?5H₂O在900℃煅烧4 h可制得纯相四硼酸锶; 延长煅烧时间可提高产物的晶化程度, 但是其晶型没有明显的变化。 用该法制备的SrB₄O₇:Eu荧光粉, 其发光强度明显比以SrCO₃和H₃BO₃为原料制备的样品高。

New Preparation Process and Influencing Factors of Strontium Tetraborate (SrB4O7)

Two hydrated strontium borate (SrB₂O₄·4H₂O and SrB₆O₁₀·5H₂O) were synthesized by liquid-phase precipitation method, and pure phase strontium tetraborate (SrB₄O₇) was obtained by high temperature calcination. The phase compositions, morphology and the high temperature sintering process of products were characterized by XRD, SEM, TG-DTA and chemical composition analysis. The effects of calcining temperature and holding time were investigated. The results show that the process of dehydration→amorphization→crystallization exists in the calcination of hydrated strontium borate. SrB₆O₁₀ is unstable at 800^oC,  and decomposed into SrB₄O₇ and liquid boron oxide. Pure strontium tetraborate was obtained with SrB₂O₄·4H₂O and SrB₆O₁₀·5H₂O as raw materials, which were calcined at 900^oC for 4 h. With the increasing of reaction time, the crystallization degrees of products are improved, but the crystal structures are unaffected essentially. SrB₄O₇:Eu phosphors were prepared using this method. It is also found that the emission intensity from the sample is higher than that synthesized using SrCO₃ and H₃BO₃ as raw materials.