带原文的文献翻译报告
NaCaPO4-SiO2系统硅酸盐-磷酸盐玻璃的直接结晶
摘要
这项研究的主题是硅酸盐-磷酸盐玻璃NaCaPO4-SiO2系统，它们是玻璃的前身-结晶材料。玻璃-通过NaCaPO4-SiO2系统结晶获得结晶材料玻璃属于一类叫做生物活性的材料。为了获得玻璃-结晶材料和预先建立的参数，让玻璃结晶在特殊条件在实验是必须的。为了设计直接结晶过程正常，有必要知道玻璃状前体的结构和微结构。微观观查显示，熔析发生在所有的玻璃研究中。基于DSC检查，它已经发现的该结晶NaCaPO4-SiO2系统的玻璃是一个多步骤的过程。测试玻璃中，在DSC曲线存在几个明显分开放热的峰值，使它可能结晶只与分离的相矩阵剩余非晶反之亦然。开展材料的详细X射线和光谱研究通过加热的梯度炉（DSC中的基础上指定的温度）得到的结果表明分离相与基体分别结晶。因此，生物活性玻璃-结晶材料可由于得到的相分离现象和结晶相的预先建立的大小的存在。
关键词：玻璃-结晶材料，直接结晶，硅酸盐-磷酸盐玻璃
第1章绪论
玻璃和NaCaPO
4-SiO
2
系统的玻璃结晶材料属于一组生理活性的材料，能够形成
与组织结合[1-10]。使用玻璃作为生物材料使得有可能采取的优点的玻璃态的特定属性，即易于获得的几乎任何形状，缓和通过控制属性化学组合物的适当的选择，以应用可能性各种加工方法，以及各向同性性能。然而，在硅酸盐 - 磷酸盐玻璃的主要特征也是它的脆弱性，这显著限制了它们的用途如生物材料。一种最好的方法就是提高眼镜的机械性能的最佳方式是执行部分结晶（失透），以获得玻璃 - 结晶材料。这种材料的特点是非常的存在的结晶相的细晶体，随机分布在在玻璃状基质的其余部分[11,12]。这使得组合两个玻璃和晶体材料的优点（高机械强度）。其结果，玻璃的结晶材料的特点是高得多的机械强度相比玻前体。然而，一个问题结晶相生长的出现会对玻璃的生物活性产生不利影响[13,14] 。在极端的情况下，不受控制的结晶可导致转换生物活性玻璃成完全惰性材料[14]。因此，有必要提供全面控制过程。正确设计这样的过程中，有必要知道玻璃状前体的结
构和微观结构。我们以往关于结构的研究和XCaPO
4-SiO
2
系统的玻璃的微结构（其
中，X=Na+或K+）表明，玻璃相分离存在于所有获得的材料[15,16]。
我们认为，问题的不受控制的生长晶相可以在硅酸盐-磷酸盐玻璃，用玻璃相分离现象减少。该分离相，基质相的边界可以是屏障限制性结晶相的生长。
这项研究的主要目的是确定NaCaPO
4含量对结晶过程的影响和NaCaPO
4
-SiO
2
系
统玻璃的热阻。
第2章实验过程
玻璃合成的详细情况在我们前面的文章中已经叙述过了[17]。用一个梯度炉对玻璃加热，玻璃的加热在温度的确定热研究的基础上（DSC）。在水平管式炉内（电加热）与硅加热元件使用。硅层厚度被温度分布控制，当为固体时，其特征在于有在最高温度该装置和中心逐渐减小朝向该管的端部。玻璃碎片放置在船与高岭土涂覆耐热钢，然后插入先前进入加热管2小时。最高温度在炉子的中心处是从确定差示扫描量热（DSC）玻璃的曲线（结晶的最高温度）。样品（加热2小时后）熔好后，从炉中抽出同加热管一起冷却。
表1 样品的组成（mol％）
进行下一步骤，沿着炉的轴线每1厘米指向读取温度并确定温度分布。
为了鉴定结晶相的类型，在结晶过程中的详细的研究X射线失透之后接收到的材料已经执行。X射线衍射数据被收集帕纳科使用Kalfa1辐射的X'Pert专业医师粉末衍射仪从铜阳极通货膨胀，配置为标准布拉格-布伦塔诺设置有锗（111）单色在入射光束，所有测量均执行每0.008步长3-75在扫描范围和205秒测量时间为每个步骤，所有测量在室温和环境压力下进行。
玻璃中红外（MIR）光谱测量用Bio-Rad公司生产的FTS60V分光计，传输技术，样品用KBr压片，扫描在4cm-1分辨率124秒后光谱被收集。
所有的玻璃受到的Netzch STA449 F1的木星进行DSC测量，运行用热通量DSC 模式，称量35mg的玻璃样品放在的铂坩埚中在干燥氮气氛以10℃/min的速率加热直至达到1000℃。得到的样品细化到晶粒尺寸小于0.1mm。
第3章结果与讨论
实验玻璃属于NaCaPO
4-SiO
2
系统，如表1组合物中给出已被选定作为研究。该
组合物被选择以[PO
4]3-和[的[SiO
4
]4-的负电荷被Na+和Ca2+阳离子补偿。
EDX的研究表明所选择的玻璃分离相和基质的化学组合物本身之间显著不同。[15,16]。因此，他们必须也有不同的结晶温度。结构研究（MIR，MAS NMR）透露，这两个分离相和基质的特征在于域结构[18]。正如上面所提到的，微观结构和玻璃结构的知识提供了一个基础直接结晶工艺设计，当然，为了以在特定的失透温度计划直接结晶过程，有必要确定玻璃态的特征温度。
热研究的玻璃的结果（DSC）都如图中所示，1，2，3，4，和5检验的DSC曲线能够得出上其耐热性受NaCaPO4含量的影响和结晶过程的NaCaPO4-SiO2系统的玻璃。如你看到的调查的玻璃的结晶（1NA的玻璃除外）发生在两个阶段的峰值的
范围在826-917℃和892-964℃。1NA玻璃的单步结晶过程几乎看不见相分离[15，16]和极少量的NaCaPO
4
。2Na-5NA玻璃的DSC曲线都是相似的，这表明这些玻璃的结晶是非常类似。此前报道的玻璃相分离暗示该矩阵相分离结晶分开，NaCaPO4的增加额在清理硅酸盐-磷酸盐玻璃的测试系统中（2Na-5NA）仅造成玻璃的耐热性增加。可以看出系统中有一个清晰的峰向上达到更高的温度（见表2），这反映了有越来越多的抗结晶物质。为了确定详细的结晶过程和直接结晶过程（在梯度炉），将选出的玻璃（2Na）进行玻璃检测。
该2Na玻璃已被选定为详细研究，因为它的特征是存在球形的纳米级相分离[15,16]。2Na玻璃的DSC曲线（如图2所示）出了两个不同的峰（在826和892℃），所以加热过程设置为800，825，870和890℃。加热过程后，得到的材料由MIR和XRD方法分析，如图6所示刚开始时玻璃的MIR光谱和在加热处理之后获得的材料。各个频带分配给各个型号的振动频率如表3中所示。在模型早期玻璃详细光谱研
究的基础上，人们发现，在NaCaPO
4-SiO
2
系统的玻璃基质具有NaCaPO4区和方石英
的结构（亚微米异质性）混合域结构。而分离阶段只有方石英区的结构出现均匀
结构域[18]，根据Gorlich [19]，玻璃失透是在结构域加热过程基础上调整方向，从而结构域可以被视为晶核，而这些决定的结晶分离相类型[17]。这一信息可以精确地描述失透过程，分析的MIR光谱如图6中所示，因此可以说，该磷酸盐相结晶为第一个结晶相。弯曲振动O-P-O磷酸-氧四面体其特点为在约575cm-1处出现800℃，然后它的强度在增加825℃和870℃[20]，在与连接先前呈现的信息，可以得出结论没有仅来自矩阵磷酸盐相中结晶的磷酸盐相仅在玻璃的基质呈现，进一步热处理（在890℃）的结果在很大程度上锐化带在约800cm-1，出现的额外条带在大约610和1197cm-1，这些频段特征为方石英[21]，从而可以推断出结晶在第二步骤中分离的方英石相和基质的结晶余量。对准确地确定的结晶相，X射线的类型进行研究，如图7所示出了在适当的温度下加热玻璃的X射线图案。X射线模式主要展示非晶态光环和几个弱反射30-35。2θ，其相位分析连接磷酸盐相（NaCaPO
4
）反射出来。你可以看到玻璃-结晶材料在玻璃加热在温度800，825，和870℃得到
的。从这可以证实的是，在调查了玻璃的情况下，在第一阶段磷酸盐相（NaCaPO
4
）结晶从基质开始。加热玻璃在890℃时会导致获得一个完全结晶材料，其中方石英相占主导地位。由此可以得出结论认为，适当地进行结晶可导致分离相完全非晶态基质的部分结晶。
结论
对NaCaPO
4-SiO
2
系统硅酸盐-磷酸盐玻璃熔离的热研究可以阻止这个系统的玻
璃结晶，NaCaPO
4
含量超过20％需要经过多个过程实现。其中所有的玻璃结晶，存
在分离相的现象十分相似如两级结晶。该玻璃的NaCaPO
4
量增加的研究将导致其结晶性显著增加。
物料在梯度熔炉中加热后获得的第一个结晶结构研究是玻璃基体（磷酸盐相
-NaCaPO
4
），然后就是分离阶段和剩余部分的基质（石英）。因此，在此研究基础上能够获得玻璃-由结晶条件合适的选择结晶材料。
致谢
该项目由美国国家科学中心根据DEC-2011 /01/ N/ST8/07425号决定颁发的。
向所有关心、支持我的老师、朋友和亲人们表示衷心的感谢。祝福我的老师、朋友和亲人们身
体健康、幸福快乐!
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Direct crystallization of silicate–phosphate glassesof
NaCaPO 4 –SiO 2 system
Abstract：The subject of the study was silicate–phosphateglasses of NaCaPO4-SiO2 system which are precursors ofglass–crystalline materials. Glass-crystalline materials of NaCaPO 4 –SiO 2 system obtained via crystallization of glasses belong to a group of the so-called bioactive materials. In order to obtain glass–crystalline materials with preestablished parameters, it is necessary to conduct crystallization of glasses at specific conditions. In order to design direct crystallization process properly, it is necessary to know the structure and microstructure of the glassy precursor. Microscopic investigation showed that liquation takes place in all the studied glasses. Based on DSC examinations, it has been found out that crystallization of the glasses of NaCaPO 4 –SiO 2 system is a multistep process. The presence of several clearly separated exothermic peaks in DSC curves of investigated glasses makes it possible to crystallize only the separated phase with the matrix remaining amorphous or vice versa. Conducted detailed X-ray and spectroscopic studies of the materials obtained by heating in a gradient furnace (in the temperature specified on the basis of DSC) showed that separated phase and matrix crystallizes separately. Therefore, bioactive glass–crystalline materials can be obtained due to the existence of the phase separation phenomenon and preestablished sizes of the crystalline phase.
Keywords：Glass-crystalline materials Direct crystallization Silicate-phosphate glasses
Introduction
Glasses and glass–crystalline materials of NaCaPO 4 –SiO 2system belong to a group of bioactive materials, capable of formingbondswith thetissue (e.g., [1–10]).Theuseofglass as a biomaterial makes it possible to take the advantage of specific properties of the glassy state, i.e., ease of obtaining practically any shape, ease of controlling properties by proper choice of chemical composition, possibility to apply various processing methods, as well as isotropic properties.
However, the main feature of the silicate–phosphate glasses is also its fragility, which significantly limits their use as biomaterials. One of the best ways to improve the mechanical properties of glasses is to perform partial crystallization (devitrification) in order to obtain glass–crystalline materials. Such materials are characterized by the presence of very fine crystalsofthe crystalline phase,randomly distributed in the rest of the glassy matrix [11,12]. This allows tocombine advantages of both glassy and crystalline materials (high mechanical strength). As a result, the glass–crystalline materials are characterized by much higher mechanical strength compared to the glassy precursors. However, a problem arises because the growth of crystalline phases very adversely affects the bioactivity yofthe glasses[13,14].In the extreme case, uncontrolled crystallization can lead to the conversion of bioactive glass into completely inert material[14]. Thus, it is necessary to provide full control over the process. To design such process properly, it is necessary to know the structure and microstructure of the glassy precursors. Our previous studies concerning the structure and microstructure of glasses of XCaPO 4 –SiO 2 system (where X = Na+ andorK+ )have shown that glass phasese paration exist in all obtained materials [15, 16].
We think that problems with uncontrolled growth of crystalline phases can be reduced in the silicate–phosphate glasses by using a glass phase separation phenomenon. The boundaries of separated phase–matrix phase may be a barrier limiting the growth of crystalline phases.
The main objective of this study was to determine the effect of NaCaPO 4 content on the crystallization process and thermal resistance of glasses of NaCaPO 4 –SiO 2 system.
Experimental
Synthesis of glasses is described in detail in our earlier article [17]. Heating of glasses at temperatures determined on the basis of thermal research (DSC) was carried out in a gradient furnace. The horizontal tube furnace (electric heating) with siliconite heating elements was used. Siliconite layer thickness is controlled temperature distribution, which is solid, wherein there is a maximum temperature in the center of the device and decreases progressively toward the ends of the tube. Pieces of glass was placed in a boat with kaolin-coated heat-resistant steel and then inserted into previously heating tube for 2 h. The highest temperature for the center of the furnace was determined from the differential scanning calorimetry (DSC) curve of glass (the maximum temperature of crystallization). The samples (after heating for 2 h) were then drawn from the furnace together with the boat and cooled.
The next step was to read the temperature at every 1 cm points along the axis of the furnace and determine the temperature distribution.
In order to identify the type of crystallizing phases during the crystallization process the detailed X-ray studies of the materials received after the devitrification have been carried out. XRD data were collected by PANalytical X’Pert Pro MD powder d iffractometer using Kalfa1 radiation from Cu anode. The configuration was standard Bragg–Brentano setup with Ge (111) monochromator at the incident beam. All measurements were performed with the 0.008 step size at 3–75 scanning range and the 205 s of measurement time for each step. Measurements were carried out under room temperature and ambient pressure.
Middle infrared (MIR) spectroscopic measurements of the glasses were made with a Bio-Rad FTS 60V spectrometer. Transmission technique, samples as KBr pellets.Spectra were collected after 124 scans at 4 cm -1 resolution.
All glasses were subjected to DSC measurements conducted on Netzch STA 449 F1 Jupiter, operating in the heat flux DSC mode. Glass samples weighing 35 mg were heated in platinum crucibles at a rate of 10 ?C min -1 in a dry nitrogen atmosphere up to 1,000 ?C. The obtained samples were refined to the grain size below 0.1 mm.
Results and discussion
Glasses belonging to NaCaPO 4 –SiO 2 systems whose composition are given in Table 1 have been selected for the studies. The composition was selected to compensate the negative charge of [PO 4 ] 3- and [SiO 4 ] 4- by Na+ and Ca2+ cations.
EDX studies showed that the chosen glasses separated phase and the matrix chemical compositions differ significantly among themselves [15, 16]. They must therefore also have different crystallization temperature. Structural studies (MIR, MAS NMR) revealed that both separated phase and matrix are characterized by a domain structure[18]. As it was mentioned above, knowledge of microstructure and structure of glasses provides a basis for the design of direct crystallization process. Of course, in order to plan the direct crystallization process it is necessary to determine characteristic temperatures for the glassy state, in particular the devitrification temperature.
The results of thermal studies (DSC) of glasses are presented in Figs. 1, 2, 3, 4, and 5. Examination of the DSC curves can trace the effect of the NaCaPO 4 content on the thermal resistance and the process of crystallization of the glasses of NaCaPO 4 –SiO 2 system. As you can
see the crystallization of investigated glasses (except of 1NA glass) takes place in two stages–peaks in the range of 826–917 and 892–964 ?C. One step crystallization process of 1NA glass is related to the almost invisible phase separation [15, 16] and very small amount of NaCaPO 4 .DSC curves of 2Na—5NA glasses are all alike—which demonstrate that the crystallization of these glasses is very similar. Earlier reported glass phase separation suggests that the matrix and separated phase crystallize separately. The increased amount of NaCaPO4 in liquidation silicate–phosphate glasses of the tested systems (2Na–5NA) results only in increased heat resistance of glasses. There is a clear, systematic shift of peaks to higher temperatures (Table 2), reflecting the increasing resistance to crystallization. To determine in detail the crystallization process of tested glasses, the direct crystallization process (in gradient furnace) of selected glass (2Na) was conducted.
The 2Na glass has been selected for detailed studies because it is characterized by the presence of spherical nanosized separated phase [15, 16]. The DSC curve of glass 2Na (Fig. 2) shows two distinct peaks (at 826 and 892 ?C), so heating process was performed at 800, 825,870, and 890 ?C. After the heating process, obtained materials were analyzed by MIR and XRD methods.Figure 6 shows the MIR spectra of the starting glass and materials received after the heating process. Assignment of the individual bands to the respective types of vibration is shown in Table 3. On the basis of earlier detailed spectroscopic studies of model glasses, it was found that in the glasses of NaCaPO 4 –SiO 2 system the glass matrix has a mixed domain structure—there are domains of NaCaPO 4 and cristobalite structure (submicroheterogenity). While separated phase have a homogeneous domain structure—only domains of cristobalite structure occur [18]. According to Go ¨rlich [19], devitrification of glasses is based on reorientation of domains during heating. Thus domains can be treated as crystallization nuclei, which will decide of the type of crystallizing phase [17]. This information allows to precisely describe the devitrification process. Analyzing MIR spectra shown in Fig. 6, it can be said that the phosphate phase crystallizes as the first one. Characteristic bending vibrations O–P–O in phospho-oxygen tetrahedrons at about 575 cm -1 appear at 800 ?C and then its intensity increase at 825 and 870 ?C [20]. In connection with the previously presented information it can be concluded that the phosphate phase crystallized only from the matrix-phosphate phase was present only in the matrix of glass. Further heat treatment (at 890 ?C) results in much sharpens of band at about 800 cm -1 , and appear of additional bands at about 610 and 1,197 cm -1 . These bands are characteristic for cristoballite [21]. As it can therefore be concluded the cristoballite crystallized in the second step—separated phase and the remainder of the
matrix crystallized. To accurately determine the type of crystallizing phases, X-ray studies were performed. Figure 7 shows a X-ray patterns of glasses heated at appropriate temperatures. X-ray patterns show mainly amorphous halo and a few weak reflections in the 30–35? 2h. The phase analysis has allowed to link this reflections with phosphate phase (NaCaPO 4 ). As you can see in the case of glasses heated at temperatures of 800, 825, and 870 ?C, we get a glass–crystalline material. This confirms that, in the case of investigated glasses, in the first stage phosphate phase (NaCaPO 4 ) crystallized from the matrix. The heating of glass at 890 ?C leads to obtain a completely crystalline material, in which the dominant phase is cristoballite. It can be concluded that properly conducted crystallization can lead to partial crystallization of the matrix in complete amorphous of separated phase.
Conclusions
Thermal studies of liquation silicate–phosphate glasses of NaCaPO 4 –SiO 2 system allow to conclude that crystallization of glasses of this system, containing more than 20 % NaCaPO 4 is a multistep process. Crystallization of all glasses in which, there is the phenomenon of phase separation is very similar—the two-stage crystallization. The increase of NaCaPO 4 amount in studied glasses causes a significant increase of their resistance to crystallization.
Structural studies of materials obtained after heating in gradient furnace shown that the first one to crystallize was the glass matrix (phosphate phase—NaCaPO 4 ), then the separated phase and the remainder of the matrix (cristo-balite). Thus, based on the investigated glasses it is possible to obtain glass–crystalline materials by appropriate selection of crystallization conditions.
Acknowledgments: The project was funded by the National Science
Center awarded on the basis of the decision number DEC-2011/01/N/
ST8/07425.
Open Access: This article is distributed under the terms of the
Creative Commons Attribution License which permits any use, dis-
tribution, and reproduction in any medium, provided the original
author(s) and the source are credited.
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