Crystallization properties of magnesium aluminosilicate glass-ceramics with and without rare-earth oxides
Crystallization properties of magnesium aluminosilicate glass-ceramics with and without rare-earth oxides
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DOI：
10.1016/j.jnoncrysol.2015.01.024
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发表时间：
2015-07
影响因子：
3.5
通讯作者：
Jing Wang;Chao Liu;Gaoke Zhang;Jun-lin Xie;Jianjun Han;Xiujian Zhao
中科院分区：
文献类型：
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作者：
Jing Wang;Chao Liu;Gaoke Zhang;Jun-lin Xie;Jianjun Han;Xiujian Zhao
以MgO-Al 2 O3-SiO2（MAS）系玻璃为原料，采用两步热处理法制备了透明微晶玻璃，研究了CeO 2和La 2 O3对MAS微晶玻璃析晶机理的影响。用场发射扫描电镜（FE-SEM）研究了透明微晶玻璃样品的微观结构。结晶活化能，E，和Avrami常数，n，通过DSC通过基辛格和Augis-Bennett方法测定。未添加稀土氧化物的试样的晶化机制为二维晶化，添加CeO 2和La 2 O3后，试样的晶化机制趋于三维晶化。经800 °C成核4 h、950 °C晶化1.5h后，无稀土氧化物的基质玻璃中析出平均粒径约20 nm的尖晶石晶体，可见光透过率保持在80%以上。不含稀土氧化物的玻璃的E值最高（362.74 kJ/mol），n值最低（2.09），对应于尖晶石的析出。随着CeO 2和La 2 O3的加入，虽然尖晶石仍是主要晶相，但尺寸增大，分布变宽。晶体的过度生长导致透射率下降到约30%。
Transparent glass-ceramics were prepared in MgO–Al2O3–SiO2(MAS) glass by two-step heat-treatments, and the effect of CeO2and La2O3on crystallization mechanism of MAS glass-ceramics was investigated. The micro-structure of the transparent glass-ceramic samples was studied by FE-SEM. Crystallization activation energy,E, and Avrami constants,n, were determined by DSC through Kissinger and Augis–Bennett methods. The crystallization mechanism of specimens without rare-earth oxides represents two-dimensional crystallization, and with the addition of CeO2and La2O3, the mechanism tends to three-dimensional crystallization. After nucleation at 800 °C for 4 h and crystallized at 950 °C for 1.5 h, spinel crystals with the mean diameter ~ 20 nm precipitated from matrix glass without rare-earth oxides, and the sample maintained the transparency over ~ 80% in visible light. The glass without rare-earth oxides showed the highest value ofE(362.74 kJ/mol) and the lowest value ofn(2.09), which is corresponding to the precipitation of spinel. With the addition of CeO2and La2O3, though the spinel is still the dominate crystal phase, the sizes increased and distributions turned to be broad. The over-growth of crystals leads the transmittance to decrease to ~ 30%.