The early stages of nucleation and crystallisation of an apatite glass-ceramic: Evidence for nano-scale crystallisation
The early stages of nucleation and crystallisation of an apatite glass-ceramic: Evidence for nano-scale crystallisation
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DOI：
10.1016/j.jnoncrysol.2010.05.102
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发表时间：
2010-12-01
影响因子：
3.5
通讯作者：
Tulyaganov, Dilshat U.
中科院分区：
文献类型：
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作者：
Hill, Robert G.;O'Donnell, Matthew D.;Tulyaganov, Dilshat U.
用差示扫描量热法(DSC)、X射线衍射法(XRD)、小角中子散射法(SANS)、飞行时间中子衍射法(TOF)和多核F-19、P-31、Al-27、Si-29魔角旋转核磁共振(MAS)谱研究了氟磷灰石(FAP)(Ca-5(PO4)(3)F)微晶玻璃的晶化过程。在FAP结晶过程中，氟被用来形成FAP相，因为众所周知，氟降低了玻璃化转变温度(T-g)，在FAP结晶时，剩余玻璃的T-g增加，这将限制FAP晶体的生长。经热处理后的玻璃的X射线衍射图显示有FAP的存在，并且有明显的谱线展宽。对谱线展宽的德拜-谢勒分析表明，微晶的平均尺寸约为11-21纳米。SANS显示玻璃是单相的，没有无定形分相的证据。SANS分析表明，热处理后的玻璃在Q=0.036 A(-1)处有一个单峰，对应于约28 nm的FAp微晶。F-19 MAS核磁共振显示玻璃中有一个广泛的共振，被鉴定为F-Ca(N)物种，它缩小了热处理的范围，并移动到靠近钙FAP中F-Ca(3)位置的位置。P-31MAS核磁共振谱表明，玻璃的结构为正磷酸盐(Q(0))和少量焦磷酸盐(P-O-P和/或Al-O-P)。在热处理时，共振变窄，并移动到2ppm，对应于晶体FAP。MAS核磁共振数据表明，晶格中有少量的镁被取代。人们认为，这种玻璃的低氟含量有助于观察纳米晶体。我们提出了在微晶玻璃材料中设计纳米氟氧化物晶相的半经验规则。皇冠版权所有(C)2010由爱思唯尔出版。保留所有权利。
Crystallisation of a fluorapatite (FAp) (Ca-5(PO4)(3)F) glass-ceramic has been studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD), small angle neutron scattering (SANS), time-of-flight (TOF) neutron diffraction and multinuclear F-19, P-31, Al-27, Si-29 magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. During crystallisation of FAp, fluorine is used in forming the FAp phase, since fluorine is known to reduce the glass transition temperature (T-g), the T-g of the residual glass increases on FAp crystallisation, which will restrict the growth of the FAp crystals. The XRD patterns of the heat-treated glass show the presence of FAp in addition there is marked line broadening. Debye-Scherrer analysis of the line broadening gives an average crystallite size of approximately 11-21 nm. SANS shows the glass to be single phase with no evidence of amorphous phase separation. SANS analysis of the heat-treated glass shows a single peak at q = 0.036 A(-1) corresponding to FAp crystallites of about 28 nm. F-19 MAS NMR shows a broad resonance identified as F-Ca(n) species in the glass, which narrows down on heat treatment and moves to position close to the F-Ca(3) site in calcium FAp. P-31 MAS NMR of the glass showed orthophosphate in structure (Q(0)) with a small amount of pyrophosphate (P-O-P and/or Al-O-P). On heat treatment the resonance narrows and shifts to 2 ppm corresponding to crystalline FAp. MAS NMR data suggests presence of small amount of Mg substituted into the lattice. It is thought that the observation of nano-crystals is aided by the low fluorine content of this glass. We have proposed semi-empirical rules for designing nano-crystalline oxyfluoride phases in glass-ceramic materials. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.