Glass-ceramic composites are heterogeneous materials that have been suggested for use as nuclear waste form materials. A one-step coprecipitation method for synthesizing rare-earth phosphates (REPO₄; RE = La or Ce) dispersed in a borosilicate glass (BG) matrix was investigated in this study. The effect of annealing temperature, ceramic loading, and oxidation state of the rare-earth precursor was explored using powder X-ray diffraction, scanning electron microscopy/energy dispersive X-ray spectroscopy, and X-ray absorption near-edge spectroscopy. REPO₄ crystallites adopting the monazite structure were observed to form when the annealing temperature was 800–1100 °C in all REPO₄–BG composite materials. Lowering the annealing temperature to 700 °C in the LaPO₄–BG composite materials caused nm sized LaPO₄ crystallites and crystalline SiO₂ to form. No changes in the local chemical environment of La or P was observed as a result of the smaller LaPO₄ crystallites. CeO₂, crystalline SiO₂, and Na₃Ce(PO₄)₂ formed in CePO₄–BG composite materials in addition to CePO₄ when the annealing temperature was below 1100 °C. CePO₄ was not observed to form in CePO₄–BG composite materials at low ceramic loadings and when annealed at 700 °C. CePO₄ was found to be the favored crystal phase over CeO₂ and Na₃Ce(PO₄)₂ in the CePO₄–BG composite materials when the annealing temperature and ceramic loading was increased. The amount of CePO₄ present was also found to be dependent on the oxidation state of the Ce precursor.

中文翻译：

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一步共沉淀法合成的稀土磷酸盐-硼硅酸盐玻璃复合材料的结晶

玻璃陶瓷复合材料是异质材料，已被建议用作核废料形式的材料。本研究研究了一种一步沉淀法，用于合成分散在硼硅酸盐玻璃（BG）基质中的稀土磷酸盐（REPO ₄ ; RE = La或Ce）。使用粉末X射线衍射，扫描电子显微镜/能量色散X射线光谱和X射线吸收近边缘光谱研究了退火温度，陶瓷负载和稀土前体的氧化态的影响。在所有REPO ₄ -BG复合材料中，当退火温度为800-1100°C时，都观察到采用独居石结构的REPO ₄晶体形成。在LaPO中将退火温度降低到700°C₄ –BG复合材料导致形成纳米级的LaPO ₄微晶和结晶SiO ₂。由于较小的LaPO ₄晶体，未观察到La或P的局部化学环境发生变化。当退火温度低于1100°C时，除了CePO ₄之外，在CePO ₄ -BG复合材料中还形成了CeO ₂，晶体SiO ₂和Na ₃ Ce（PO ₄）₂。CEPO ₄未观察到形式CEPO ₄时在700℃下退火以低负荷陶瓷-BG复合材料和。CePO ₄当增加退火温度和陶瓷负载量时，CePO ₄ -BG复合材料中的CeO ₂和Na ₃ Ce（PO ₄）₂比CeO ₂和Na ₃ Ce（PO ₄）₂更有利。还发现存在的CePO ₄的量取决于Ce前体的氧化态。