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首页> 外文期刊>European Journal of Glass Science and Technology, PartB. Physics and Chemistry of Glasses >MAS NMR study of the crystallisation process of apatite-mullite glass ceramics
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MAS NMR study of the crystallisation process of apatite-mullite glass ceramics

机译：磷灰石-莫来石玻璃陶瓷结晶过程的MAS NMR研究

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摘要

The crystallisation behaviour of 4(center dot)5SiO_2.3Al_2O_3,1(center dot)5P_2O_5.(5-z)CaO.zCaF_2 glasses with z between 0 and 3 were investigated using differential scanning calorimetry(DSC),x-ray diffraction analysis and ~(27)A1,~(29)Si,~(31)P and ~(19)F magic angle spinning nuclear magnetic resonance(MAS-NMR)spectroscopy.The glasses showed two exothermic peaks at Tpl and Tp2 due to crystallisation,which decreased in temperature with fluorine content.In the nonfluorine containing glass(z=0),whitlockite(Ca_3(PO_4)_2 and anorthite(2SiO_2.Al_2O_3.CaO)were the final crystallisation products.In the fluorine containing glasses(z=2 and 3),fluorapatite(FAP)(Ca_5(PO_4)_3,crystallised at Tpl and mullite(2SiO_2.3Al_2O_3)at Tp2.MAS-NMR results showed that a glass phase remained after crystallisation.The coordination state of the phosphate species in the glass drastically changed during crystallisation.Five coordinate Al,Al(V),in the glass containing fluoride disappeared after crystallisation of mullite.The ~(27)Al and ~(29)Si MAS-NMR spectra did not change significantly during fluorapatite crystallisation,but changed markedly on mullite formation.~(19)F MAS-NMR demonstrated the presence of FAP in the heat treated glasses.In the glasses with a higher fluorine content than that required to convert all the Ca and P to FAP a Al-F-Ca(n)type species remained in the residual glass phase.
机译：采用差示扫描量热法（DSC），x射线衍射分析技术研究了z在0和3之间的4（中心点）5SiO_2.3Al_2O_3,1（中心点）5P_2O_5。（5-z）CaO.zCaF_2玻璃的结晶行为。以及〜（27）A1，〜（29）Si，〜（31）P和〜（19）F魔角旋转核磁共振（MAS-NMR）光谱。由于结晶，玻璃在Tpl和Tp2处显示两个放热峰。在含氟玻璃（z = 0）中，辉晶石（Ca_3（PO_4）_2和钙长石（2SiO_2.Al_2O_3.CaO）是最终的结晶产物。在含氟玻璃中（z = 2和3），氟磷灰石（FAP）（Ca_5（PO_4）_3，在Tpl处结晶，莫来石（2SiO_2.3Al_2O_3）在Tp2处结晶。玻璃在结晶过程中发生了剧烈变化。含氟玻璃中的五坐标Al，Al（V）在结晶后消失了。氟磷灰石结晶过程中〜（27）Al和〜（29）Si MAS-NMR谱图变化不大，但在莫来石形成时变化显着。〜（19）F MAS-NMR证明了热处理后FAP的存在在氟含量高于将所有Ca和P转化为FAP所需的氟含量的玻璃中，Al-F-Ca（n）型物质残留在残留的玻璃相中。

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