Abstract—

Magnesium oxide (MgO) and orthophosphoric acid (H₃PO₄) have been reacted at different pH values to study the effects of alkalinity on the characteristic features of magnesium phosphate material. The phases of the synthesized samples have been identified as newberyite (with the chemical formula of MgHPO₄ ⋅ 3H₂O and the pdf no. 01-075-1714) and magnesium phosphate hydrate (with the chemical formula of Mg₃(PO₄)₂ · 22H₂O and the pdf no. 00-044-0775), in the X-ray powder diffraction analyses results. The characteristic band values of samples have been characterized by FTIR and Raman spectroscopies. The differences in morphologies have been studied with Scanning Electron Microscope (SEM). The largest particles in the range of 3.16–9.85 µm have been seen in the shape of nested flat sheets at pH 10 while the smallest particles between 1.17–2.04 µm have been obtained in the shape of an ellipse at pH 7. According to the thermogravimetric analyses, the differences in thermal behaviours have been determined. MgHPO₄ · 3H₂O has lost its crystal water by a two-step reaction while Mg₃(PO₄)₂ · 22H₂O has dehydrated by a single-step reaction. Obtained results indicate that the crystal structure and surface morphology of the synthesized compound can be modified by the alkalinity of the reaction medium.

中文翻译：

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碱度对磷酸镁水合物特性和形态的影响

摘要-

氧化镁（MgO）和正磷酸（H ₃ PO ₄）在不同的pH值下反应，以研究碱度对磷酸镁材料特性的影响。合成样品的相位已被鉴定为newberyite（与MgHPO的化学式₄ ⋅3H ₂ O与PDF号01-075-1714）和磷酸镁的水合物（用Mg的化学式₃（PO ₄）₂ ·22H ₂O和pdf号 00-044-0775），在X射线粉末衍射分析结果中。样品的特征谱带值已通过FTIR和拉曼光谱学进行了表征。已经用扫描电子显微镜（SEM）研究了形态上的差异。在pH 10时，可以看到嵌套平板的最大颗粒范围为3.16-9.85 µm，而在pH 7时，可以看到椭圆形的最小颗粒为1.17-2.04 µm。根据热重分析分析，已经确定了热行为的差异。MgHPO ₄ ·3H ₂ O通过两步反应失去了结晶水，而Mg ₃（PO ₄）₂ ·22H ₂O通过一步反应脱水。所得结果表明，通过反应介质的碱度可以改变合成化合物的晶体结构和表面形态。