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Structural characteristic and formation mechanism of hemihydrate calcium sulfate whiskers prepared using FGD gypsum

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Particuology 2022年第3期20卷 98-103页

作者： Xiaoting Zhang Lingwei Ran Xiao Wang Biao Jin Jianwu Zhang Shanying Li Liushuan Yang Department of Civil&Material Engineering Henan University of Urban ConstructionPingdingshan 467036HenanChina不详

Hemihydrate calcium sulfate whiskers(HH-CSWs)were hydrothermally synthesized in a sulfuric acid solution at 120℃ for different holding times(20,40,and 60 min).The phase structures and morphologies were characterized by XRD and SEM,respectively.The XRD pattern of the sample under 60 min was refined via the rietveld fitting method.The structure models of the HH-CSW sample under a 60-min holding time was established based on rietveld fitting results.No difference in the positions of diffraction peaks was determined.The as-prepared holding time increased the intensity and aspect ratio of the diffraction peaks of both samples.In the prepared HH-CSW structure,Ca-O polyhedron is a 12-sided polyhedron similar to that in the gypsum structure;the Ca atom is located in two positions in the one-unit cell;the H_(2)O channel along the c-axis similar is O-shaped and bigger than that in hexagonal and monoclinic CaSO_(4)·0.5H_(2)O structures.Therefore,although the prepared HH-CSW crystals’structure are similar to that of the reported hexagonal and monoclinic CaSO_(4)·0.5H_(2)O structures,they are not the same.The formation mechanism of HH-CSW from flue gas desulfurization(FGD)gypsum is discussed based on the analysis of gypsum structure.

关键词： FGD gypsum HH-CSW rietveld method Crystal structure

Various admixtures to mitigate the long-term strength retrogression of Portland cement cured under high pressure and high temperature conditions

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第1期15卷 191-203页

作者： Jiankun Qin Xueyu Pang Ashok Santra Guodong Cheng Hailong Li School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580China Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580China Drilling Technology Team Aramco Americas:Aramco Research Center16300 Park Row DriveHoustonTX77084USA

In order to investigate the problem of long-term strength retrogression in oil well cement systems exposed to high pressure and high temperature(HPHT)curing conditions,various influencing factors,including cement sources,particle sizes of silica flour,and additions of silica fume,alumina,colloidal iron oxide and nano-graphene,were investigated.To simulate the environment of cementing geothermal wells and deep wells,cement slurries were directly cured at 50 MPa and 200?C.Mineral compositions(as determined by X-ray diffraction rietveld refinement),water permeability,compressive strength and Young’s modulus were used to evaluate the qualities of the set cement.Short-term curing(2e30 d)test results indicated that the adoption of 6 m m ultrafine crystalline silica played the most important role in stabilizing the mechanical properties of oil well cement systems,while the addition of silica fume had a detrimental effect on strength stability.Long-term curing(2e180 d)test results indicated that nano-graphene could stabilize the Young’s modulus of oil well cement systems.However,none of the ad-mixtures studied here can completely prevent the strength retrogression phenomenon due to their inability to stop the conversion of amorphous to crystalline phases.

关键词： High pressure and high temperature(HPHT) Strength retrogression Young’s modulus Water permeability rietveld method

Inter-comparative Study of Quantitative methods of Industrial Clinker

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Journal of Wuhan University of Technology(Materials Science) 2017年第6期32卷 1250-1260页

作者： Benmohamed Mohamed Galai Haykel Alouani Rabah Bejaoui Marouene Ben Haj Amara Abdessalem Ben Rhaim Hafsia UR05/13-01 Physique des Materiaux Lamellaires et Nanomateriaux Hybrides (PMLNMH) Faeulte des Sciences de Bizerte Universitede Carthage Zarzouna 7021 Tunisia Institut National de Recherche et d'Analyse Physico-chimiques 2026 Technopole de Sidi Thabet Tunisia

Impurities from the raw materials, the grinding and the homogenization of the raw materials, the kiln instability and the complexity of the cooling step, all these factors make it difficult to obtain a perfect evaluation of the mineralogical composition of Portland clinker. We studied the limitations of the most commonly used quantitative methods and recommend some procedures to obtain reliable and reproducible results of quantitative analyses. Different clinker samples（provided by the Bizerte Cement Company（Tunisia）） were subjected to an elemental analysis by X-ray fluorescence and the mineralogical composition was determined by the Bogue calculation and by X-ray powder diffraction combined with the rietveld method（Different softwares were used： XPert High Score Plus version 2.0 and TOPAS version 4.2）. We then compared the results obtained by the rietveld method and the Bogue calculation to the specific peak areas of each phase. The content of each phase, determined by the rietveld method, varied proportionally to the change in peak area; a significant difference in these results was found by using the elementary Bogue calculation.

关键词： portland clinker bogue calculation rietveld method quantitative mineralogy specificpeaks different software

Crystal structural refinement for NdAlSi

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Rare Metals 2006年第4期25卷 355-358页

作者： HE Wei ZHANG Jiliang ZENG Lingmin ZHUANG Yinghong Institute of Materials Science Guangxi University Nanning 530004 China

The compound NdAlSi was studied using X-ray powder diffraction technique and refined by the rietveld method. The compound NdAlSi has tetragonal α-ThSiE-type structure, space group I41/amd （No. 141）, Z = 4, and the lattice parameters a = 0.41991（1） nm, c = 1.44916（3） nm. The Smith and Snyder figure of merit FN is F30= 103.1（36）. The R-factors of rietveld refinement are Rp= 0.113 and Rwp= 0.148, respectively. The X-ray powder diffraction data is presented in this article.

关键词： NdAlSi crystal structure X-ray powder diffraction data rietveld method

Structure and Crystal Growth of Li_2Zn_2(MoO_4)_3

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Chinese Journal of Structural Chemistry 2007年第10期26卷 1208-1210页

作者：薛丽平林璋黄丰梁敬魁 Fujian Institute of Research on the Structure of Matter The Chinese Academy of Sciences

Single crystal of Li2Zn2（MoO4）3 has been grown from a flux of Li2MoO4 by the top-seeded solution-growth method, and its stnicture was refined by the rietveld method. It belongs to the orthorhombic system, space group Pnma with a = 5.1114, b = 10.4906 and c = 17.6172A. Good agreement between the experimental and calculated profile （Rp = 6.69%, Rwp = 9.73% and Rexp = 6.58%） was reached.

关键词： Li2Zn2 （MoO4）3 rietveld method crystal structure crystal growth

Quantitative Phase Analysis of the Calcium Silicate Slag as the Residue of Extracting Alumina from High-Alumina Fly Ash

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Journal of Shanghai Jiaotong university(Science) 2016年第6期21卷 729-736页

作者：黄冬波宗燕兵刘晓明彭丹丹杨志杰 School of Metallurgical and Ecological Engineering University of Science and Technology Beijing State Key Laboratory of Solid Waste Reuse for Building Materials Beijing Building Materials Academy of Sciences Research National Energy Key Laboratory of High Aluminium Coal Development and Utilization Datang International Power Generation Co.Ltd.

Calcium silicate slag is the residue of process of pre-desilication alkali lime sintering applied in the high-alumina fly ash to extract the alumina.The quantitative phase analysis(QPA) of the calcium silicate slag has been performed by the rietveld method based on the powder X-ray diffraction(XRD) with the aid of noncommercial software GSAS-EXPGUI.A known weight of crystalline internal standard(10% CaF_2) was added to the calcium silicate slag to calculate the fraction of amorphous phase and other crystalline phases on an absolute basis.Besides,the calcium silicate slag was characterized by X-ray fluorescence(XRF) and thermo gravimetric(TG) differential scanning calorimetry(DSC) to test the QPA results and investigate its other characters.Finally,the results show that the amorphous fraction is 17.5%(hereinafter,the percentages refer to the mass fraction),and the major crystalline phases detected in the calcium silicate slag consist of 23.5% Beta-Ca_2 SiO_4,10.0% bredigite,10.3% Ca_3Al_2O_6(C_3A) and 21.6% CaCO_3.

关键词： calcium silicate slag X-ray diffraction(XRD) quantitative phase analysis(QPA) rietveld method

Discovery of Stolzite in China and Refinement of Its Crystal Structure

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Acta Geologica Sinica(English Edition) 1995年第1期69卷 111-116页

作者： Xu Keqin, Xue Jiyue, Ding Yang, Department of Earth Sciences, Nanjing U niversity, Nanjing, Jiangsuand Lu Guanglie Central Laboratory of Hangzhou U niversity, Hangzhou, Zhejiang Fei Zhenbi Department of Earth Sciences Nanjing University Nanjing Jiangsu China

Although stolzite was discovered in Yaogangxian, Hunan Province, China, in 1948, no formal report about this mineral has been published. Recently its crystal structure has been refined by means of the rietveld method. The cell dimensions of the mineral are: a=b= 0.544503(3) nm, c= 1.20495(1)nm and α=β=γ=90° . The X, Y and Z coordinates of the atom O refined by the authors are 0.2637, 0.1137 and 0.0706, respectively. The length of the W-O bond is 0.17826 nm and the angle of the O-W-O bound are 123° and 103° ,respectively.

关键词： stolzite rietveld method refinement of crystal structure Yaogangxian Hunan Province

Quantifying Isotibolone in Raw Materials of Tibolone

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Pharmacology & Pharmacy 2013年第3期4卷 283-287页

作者： Selma Gutierrez Antonio Ariel Gomes Fabio Furlan Ferreira Gabriel L.B.Araujo Carlos O.Paiva-Santos Departamento de Físico-Química Instituto de QuímicaUniversidade Estadual PaulistaAraraquaraBrazil Department of Physics University of GuelphGuelphCanada Centro de Ciencias Naturais e Humanas Universidade Federal do ABCSanto AndreBrazil Faculty of Pharmaceutical Sciences Department of PharmacyUniversity of Sao PauloSao PauloBrazil

Tibolone, a synthetic steroid, is used in the treatment of natural or surgical menopause disturbs resultant of estrogenic deficiency. Isotibolone (Δ4-tibolone) is one of the three active metabolic degradation products of tibolone that displays progestagenic effects on carcinoma cell growth and gene regulation. Isotibolone can be present in raw material of tibolone due to some inadequate synthesis or storage. Its presence is necessary to be identified and quantified in active pharmaceutical ingredients (API), before its use in the manufacturing of medicines. After a recent study on the crystal structure determination of isotibolone, quantitative phase analyses of both tibolone and isotibolone in raw materials and tablets became possible to be conducted. X-ray powder diffraction is one recommended tool for this purpose, but it can be highly frustrating due to the extreme peak overlap when conventional laboratory equipments are used. In this work we show that the use of Brazilian Synchrotron Light Source X-ray powder diffraction data and the rietveld method can be successfully applied to identify and quantify the isotibolone in two samples of tibolone raw materials.

关键词： Hormones rietveld method X-Ray Powder Diffractometry Synchrotron Radiation Quantitative Phase Analysis

三元金属间化合物La_3Cu_3Bi_4的合成、结构与性能研究(英文)

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Journal of Shanghai University(English Edition) 2008年第6期12卷 486-488页

作者：鲁玉明范峰蔡传兵曹世勋张金仓 Department of Physics College of Sciences Shanghai University

The new intermetallic compound La3Cu3Bi4 was synthesized by arc melting method followed by annealing. The crystal structure refined using the rietveld method and X-ray powder diffraction data showed to be Y3Au3Sb4 structure type with space group I-^43D （No.220）. The unit cell parameters were a = 0.997 797（7） nm and V = 0.993 41（2） nm^3. The structure was characterized by covalent Cu-Bi4 tetrahedron, which formed three-dimensional network by sharing corners and La atoms separated in the space of Cu-Bi4 tetragon. The expansion of La3Cu3Bi4 studied by using low temperature X-ray diffraction showed to be positive expansion and diminished with the temperature rising.

关键词： rare earth copper bismuth intermetallics rietveld method