Yuan P.,CAS Guangzhou Institute of Geochemistry |
Yuan P.,Guangdong Provincial Key Laboratory of Mineral Physics and Materials |
Tan D.,Southwest University of Science and Technology |
Annabi-Bergaya F.,CNRS Center for Research on Divided Matter
Applied Clay Science
Halloysite is a natural nanosized tubular clay mineral that has many potentially important uses in different industrial fields. In this paper, the key structural characteristics and properties of halloysite and their related applications are comprehensively reviewed. Research advances on halloysite, especially those from the past 20. years, are summarized with some critical comments. Attention is mainly paid to the structure and morphology of halloysite and their changes, the formation of tubular structures, the physicochemical properties, the surface chemical modifications, and the halloysite-based advanced materials and some related applications. Additionally, future prospects and key problems to be solved in halloysite studies are discussed. This review shed new light on both fundamental and applied studies that focused on halloysite. © 2015 Elsevier B.V. Source
Xiande X.,CAS Guangzhou Institute of Geochemistry |
Xiande X.,Guangdong Provincial Key Laboratory of Mineral Physics and Materials |
Jianbo W.,Wuhan University |
Xiangping G.,Central South University |
And 2 more authors.
The mineralogy of shock vein matrix in the Suizhou meteorite has been investigated by optical and transmission electron microscopy. It was revealed that the vein matrix is composed of majorite-pyrope garnet, magnesiowüstite, and ringwoodite, with FeNi–FeS intergrowths. The observation and character of ring-like selected electron diffraction (SAED) patterns indicate that the idiomorphic garnet crystals in the vein matrix have different orientations. The polycrystalline nature of magnesiowüstite is also confirmed by a ring-like SAED pattern. Both garnet and magnesiowüstite crystals showed sharp diffraction spots, signifying the good crystallinity of these two minerals. The SAED pattern of cryptocrystalline ringwoodite shows only diffuse concentric diffraction rings. FeNi metal and troilite (FeS), which were molten during the shock event, occur in the matrix as fine eutectic FeNi–FeS intergrowths filling the interstices between garnet and magnesiowüstite grains. Based on the phase diagram of the Allende chondrite and the results of this TEM study, it is inferred that majorite-pyrope garnet first crystallized from the Suizhou chondritic melt at 22–26 GPa, followed by crystallization of magnesiowüstite at 20–24 GPa, and then ringwoodite at 18–20 GPa. The eutectic intergrowths of FeNi-metal and troilite are proposed to have crystallized during meteorite cooling and solidified at the last stage of vein formation. © 2016, Science Press, Institute of Geochemistry, CAS and Springer-Verlag Berlin Heidelberg. Source
Cheng Y.,Northeastern University China |
Huang F.,Northeastern University China |
Li W.,Northeastern University China |
Liu R.,Northeastern University China |
And 2 more authors.
Construction and Building Materials
High-silicon iron tailings, which have been mechanochemically activated, was used for the preparation of concrete as a supplementary cementing material to substitute cement (by 10%, 20%, 30% and 40% respectively) based on their composition, particle sizes and pozzolanic activity. With the aid of tests, this paper discusses the effects of the tailings on the compressive strength of concrete. Tests show that with an increase in substitution rate of cement in the tailings, the compressive strength of concrete tends to decrease, and when the substitution rate is at 10%, 20% and 30% respectively, the compressive strength of concrete is measured up to the design requirement; if an appropriate amount of water reducing admixture is added while cement is substituted by tailings with a substitution rate of 10%, 20%, 30% and 40% respectively, the compressive strength of concrete is also measured up to the design requirement. The research result demonstrates that as far as the compressive strength concerned, it is feasible to use mechanochemically activated high-silicon iron tailings as a supplementary cementing material to partly substitute cement in concrete. © 2016 Elsevier Ltd. All rights reserved. Source
Niu J.,China University of Mining and Technology |
Niu J.,Guangdong Provincial Key Laboratory of Mineral Physics and Materials |
Shen S.,China University of Mining and Technology |
Zhou L.,China University of Mining and Technology |
And 4 more authors.
Anatase microspheres composed of porous single crystals were successfully synthesized via a facile route without preseeding treatment and then further modified using a surface hydrogenation process. The porous materials obtained exhibit excellent photocatalytic activity and good recyclability leading to great potential in practical applications. © 2016 The Royal Society of Chemistry. Source
Xian H.,CAS Guangzhou Institute of Geochemistry |
Xian H.,Guangdong Provincial Key Laboratory of Mineral Physics and Materials |
Xian H.,University of Chinese Academy of Sciences |
Zhu J.,CAS Guangzhou Institute of Geochemistry |
And 5 more authors.
Synthesis of iron pyrite with defined morphology has long been actively pursued, due to the strong size and shape dependence of their chemical and physical properties. This review provides comprehensive information outlining current knowledge regarding the morphology controllable syntheses of micro- and nano-iron pyrite mono- and poly-crystals. The wet-chemical methods are summarized as the controllable syntheses, including the hydrothermal, solvothermal, hot-injection and heating-up methods, sulphidation and methods with other relatively high efficiencies. The present study reveals the discussion of relationship between the morphologies and major controlling factors, the temperature, precursor chemicals, solvents and surfactants. The existing challenges for future fine tuning of iron pyrite facets are also proposed for improving the performance of iron pyrite based materials. © The Royal Society of Chemistry 2016. Source