Wen ZHANG
材料科学技术（英文）
Macroporous silicon nitride (Si3N4) ceramics with high strength, uniform structure and relatively high porosity were obtained by gelcasting and carbonthermal reaction in a two-step sintering technique. Microstructure and composition were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD). Open porosity, pore size distribution and basic mechanical performance were measured by Archimedes method, mercury intrusion porosimetry and three-point bending methods, respectively. SEM and TEM results revealed that pores were formed by elongated β-Si3N4. SADP measurement proved the formation of SiC particles. The SiC granules were beneficial for the formation of high ratio elongatedβ-Si3N4, and at proper amount, they also acted as reinforcement phase. Thermodynamic analysis indicated that the mechanisms of the reactions were mainly associated with liquid-solid reaction and gas-liquid reaction.
关键词:
Ceramics
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null
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null
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Jiancun RAO
,
Yu ZHOU
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Douxing LI
材料科学技术（英文）
A new type of long periodic structure has been found in ZrO2-Y2O3 ceramics in annealed states. High resolution electron microscopy (HREM), selected area electron diffraction, and computer simulation have been used to reveal the presence of the long periodic structure. The unit cell of the long periodic structure consists of a cubic ZrO2 unit cell and L10- like phase one.
关键词:
Ceramics
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null
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null
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null
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段寒凝
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伍茂松
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邱洋
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霍绍新
低温物理学报
溶胶凝胶法制备了Na0．5Bi0．5Ti1-xMnxO3（x=0，0．02，0．04）陶瓷样品，X射线衍射（XRD）分析表明陶瓷样品均形成了单一的钙钛矿（ABO3）型结构且没有杂质相的形成．随着Mn含量的增加，XRD峰向高角度方向移动，表明Mn离子进入Na0．5Bi0．5TiO3晶格．掺杂样品均表现出室温铁磁性和铁电性．磁测量表明样品中存在复杂的磁相互作用，包括铁磁，反铁磁和顺磁相互作用．以上结果表明，通过Mn的掺杂可以使铁电材料Na0．5Bi0．5TiO3转变为多铁材料．
关键词:
Na0．5Bi0．5TiO3
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陶瓷
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多铁性
