Thermal expansion of kyanite at ambient pressure:An X-ray powder diffraction study up to 1000℃

The thermal expansion coefficients of kyanite at ambient pressure have been investigated by an X-ray powder diffraction technique with temperatures up to 1000 ℃. No phase transition was observed in the experimental temperature range. Data for the unit-cell parameters and temperatures were fitted empirically resulting in the following thermal expansion coefficients： αa = 5.8（3） × 10^-5, αb = 5.8 （1）× 10^-5, αc = 5.2（1）× 10^-5, and αv = 7.4（1） × 10^-3 ℃ 1 in good agreement with a recent neutron powder diffraction study. On the other hand, the variation of the unit-cell angles α, β and γ of kyanite with increase in temperature is very complicated, and the agreement among all studies is poor. The thermal expansion data at ambient pressure reported here and the compression data at ambient temperature from the literature suggest that, for the kyanite lattice, the most and least thermally expandable directions correspond to the most and least compressible directions, respectively.

Ab initio Structure Determination of [Co(NH_3)_5Br]Br_2 Using Conventional X-ray Powder Diffraction

The crystal structure of [Co(NH3)5Br]Br2 has been determined ab initio from the conventional X-ray powder diffraction data. The approximate structure with all 7 indeyendent non-H atoms was solved by direct methods. The final orthorhombic unit-cell parameters after Rietveld refinement are: a=13.6927, b=10.7071, c=6.9400A, V=1017.47A3, F30=93(0.0075,43), M20=49, Z=4. Space group is Pnma. The structure agreement factors are: Rp=0.066,Rwp=0.090, RF=0.041, RB=0.042.

X-ray fluorescence spectrometry determination of open-hearth furnace slag by pressed powder briquetting

A rapid analysis method of determining content of eight compounds of open-hearth furnace slag was developed using X-ray fluorescence spectrometry and pressed powder briquettes. Matrix effect was corrected using theoretical alpha coefficient. Grains-size effect was eliminated by optimized sample preparation technique parameters. Mineral effect was corrected with standard curve of specially made standard samples. The analysis results of TiO2, TFe, SiO2, MgO, Al2O3, CaO, MnO and P2O5 in slag samples showed that both precision and accuracy are comparable with that of chemical method.

Rietveld Refinement and X-ray Powder Diffraction Data of GdAlSi

The X-ray powder diffraction data of the compound GdAlSi was studied by means of X-ray diffraction technique and refined by Rietveld method. The compound GdAlSi has tetragonal α-ThSi_2-type structure, space group I4_1/amd (No.141), Z=4, the lattice parameters a=041234 (1) nm, c=1.44202(1) nm. The Smith and Snyder figure of merit [5] F_N is F_ 30=2521(36). The R-factors of Rietveld refinement are R_p=0.098 and R_ wp=0.128. The X-ray powder diffraction data are given. The field dependence of the magnetization measured at room temperature and the temperature variation of the inverse magnetic susceptibility of the compound GdAlSi were also presented.

Neutron powder diffraction and high-pressure synchrotron x-ray diffraction study of tantalum nitrides

Tantalum nitride （TAN） compact with a Vickers hardness of 26 GPa is prepared by a high-pressure and high- temperature （HPHT） method. The crystal structure and atom occupations of WC-type TaN have been investigated by neutron powder diffraction, and the compressibility of WC-type TaN has been investigated by using in-situ high-pressure synchrotron x-ray diffraction. The third-order Birch-Murnaghan equation of state fitted to the x-ray diffraction pressure- volume （P-V） sets of data, collected up to 41 GPa, yields ambient pressure isothermal bulk moduli of B0 = 369（2） GPa with pressure derivatives of B~ = 4 for the WC-type TaN. The bulk modulus of WC-type TaN is not in good agreement with the previous result （Bo = 351 GPa）, which is close to the recent theoretical calculation result （Bo = 378 GPa）. An analysis of the experiment results shows that crystal structure of WC-type TaN can be viewed as alternate stacking of Ta and N layers along the c direction, and the covalent Ta-N bonds between Ta and N layers along the c axis in the crystal structure play an important role in the incompressibility and hardness of WC-type TaN.

X-ray Powder Diffraction Data and Rietveld Refinement for NdCoGe_3

オ-ray powder diffraction data and crystal structure of RE compound NdCoGe3 were studied by using X-ray powder diffraction and refined by the Rietveld profile fitting method. The compound has the tetragonal BaNiSn3type structure, space group I4mm (No.107) a=0.42961(2) nm, c=098147(4) nm, V=0.018114 nm3, Z=2 and Dx=7.717 g·cm-3. The figure of merit FN for the powder data is F30=623 (0.0107, 45). Structure refinement was performed with 110 reflections and led to Rp=11.78% and Rwp=16.56%.

X-ray Powder Diffraction Pattern of Bi_4(SiO_4)_3

In cooperation with figure-of-merits the Rietveld analysis can appraise both angular and intensity data of powder diffraction. In this work, X-ray diffraction pattern of Bi4(SiO4)3 was redetermined with intensity figure-of-merits, which qualify agreement between observed and calculated relative intensities. F30 is 158.90 (0.0059, 32), intensity figure of merit Rint is 8.7, I20(17), 8.0. The values of figure-of-merits show that the data of JCPDS cards are distorted. Both the experimental and calculated peak positions and heights are listed in detail.

SYNTHESIS AND X-RAY POWDER STUDY OF A NEW COMPOUND:Ba_6Ti_7Nb_9O_(42)

A new compound Ba6Ti7Nb9O42 was prepared for the first time by solid state reaction in BaO-TiO2-Nb2O5, ternary system. The X-ray powder diffraction data of the title compound was determined. Ba6Ti7Nb9O42 crystallizes in the hexagonal system -with unit cell parameters a=9.0527(4) A,c=11.790(1) A,and space group P63/mcm(193),z=1. The calculated and measured densities are 5. 293 g/cm3 and 5.285 g/cm3, respectively.

IDENTIFICATION AND SIMULATION OF X-RAY POWDER DIFFRACTION PATTERN

A new method for pattern identification and simulation of X-ray powder diffraction data is described, which can give definite phase composition of the unknown rapidly and correctly. The method is implemented in Microsoft Fortran 77 for the IBM PC/XT/AT personal computer or their compatibles.

MY RESEARCH ACHIEVEMENTS IN POWDER X-RAY DIFFRACTION & PHASE DIAGRAMS

I graduated from the Department of Chemistry, Xiamen University in 1955, majoring in physical chemistry. I went to the Institute of Metallurgy under the Soviet Academy of Sciences in 1956 as a Ph.D.candidate in thermochemistry and crystal chemistry of metal alloys,and got my Ph.D.degree in 1960.In the following 30 years, I did basic and applied research in interdisciplines,including crystal chemistry,materials science and solid state physics.My main achievements can be listed in two aspects as follows:

Silicon assistant carbothermal reduction for SiC powders

The silicon assistant method to increase the reaction yield of carbothermal reduction of silica at a lower temperature is reported. The effect of silicon on the carbothermal reduction process has been investigated in detail. Compared with traditional reduction, the introduction of silicon can change the reaction path and further increase the conversion of silicon carbide at a lower temperature. It is considered that the assistant reduction consists of three steps： vaporizing and melting of silicon, formation of silicon monoxide, and synthesis of silicon carbide. The morphology of the synthesized SiC powders through the silicon assistant method can be affected apparently by the experimental temperature.

Characteristics of mechanical alloyed Ni-Al powder for sintering

Mechanical alloying was employed to obtain high-activity Ni-AI powder. The effects of mechanical alloying on the microstructure and characteristics of milled powder with a normal composition of Ni-22.89 at.% AI-0.5 at.% B were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The results show that a solution Ni （AI） was obtained after milling. During mechanical alloying, the milled powder obtains extra surface energy and crystalline energy because the crystallite size becomes free and the lattice strain increases with the milling time prolonging. Furthermore, about 0.5 mol% oxide in the particles were formed after milling, and this kind of dis- persed oxide is effective to improve the properties of the sintered alloy by dispersion strengthening. It is confirmed that Ni3AI alloy with outstanding properties has been prepared with mechanical alloyed powders.

Reactivity of Recycled Glass Powder in a Cementitious Medium

The reactivity of the recycled glass powder (GP) in a cementitious medium has been studied over time by means of X-ray diffraction and thermal gravimetric analysis. Two different mixtures based on cement/glass powder (0 or 20 wt% GP) and lime/glass powder (70 wt% GP) were considered. Analysis revealed the coexistence of both hydration and pozzolanic reaction during the hardening of the mortars. At young age, the cement hydration would prevail over the pozzolanic one resulting in a decrease of physico-chemical and mechanical properties of the material due to the dilution effect. The pozzolanic reaction that predominates from 91 days, would induce the formation of supplementary C-S-H leading to improve the material properties.

PREPARATION OF ULTRAFINE ALLOY POWDER BY REDUCTION OF COMPLEX OXIDE

The ultrafine alloy powders,CuRh,γ-Ni_(0.33)Fe_(0.66) and α-Fe_(0.66)Co_(0.33) of size less than 35 nm were prepared by reduction of complex metallic oxides under atmosphere of 15% H_2 and 85%Ar.

Thermal expansion of lattice parameter of (powder) silicon up to 1473 K

The XRPD (X-ray powder diffxactometry) patterns of silicon powder with a unit cell structure of diamond were determined from 298 to 1473 K. Lattice parameters of Si linearly increase with temperature. The thermal shifts of the positions of all reflection peaks are linearly correlated with the temperature. The coefficients of the intrinsic linear thermal expansion and volumetric thermal expansion were determined as 3.87×10-6/K and 1.16×10-5/K respectively. It indicates that Si is still a suitable standard in the XRPD method at high temperatures.

X-RAY RIETVELD STRUCTURE REFINEMENT OF ErNiSb

The crystal structure of compound ErNiSb has been refined by the Rietveld wholepatternfitting method from X-ray powder diffraction data.The compound ErNiSb is cubic, space group F43m and the structure parameters and reliability factors were refined to be a=6.268 3(1), V=246.29^(3), Z=4, D_(x)=9.377 g/cm^3, R_(B)=3.57%, R_(F)=3.64%, R_(p)=6.63%, R_(WP)=8.80%.

Performance of engineered cementitious composite containing stone slurry powder waste

Most of the materials used in engineered cementitious composite are fine in size to achieve ductile nature.Stone slurry powder(SSP)is an inert material obtained from stone industries as by-product which may cause hazardous impact on environment.In this research work,partial replacement of silica sand(SS)and fine sand(FS)by SSP with different contents(25%and 50%each)for making engineered cementitious composite has been explored.The performance was evaluated on the basis of strength,tensile strain,mid span deflection capacity,ultra-sonic pulse velocity and microstructure.Mechanical strength was found to be increased at 25%SSP in both replacements;whereas,strength decreased slightly at 50%replacement.Tensile strain,mid span deflection and quality of concrete were enhanced with increase in SSP content.Using SSP formed denser cementitious composite can help to save the natural resources and contribute in making green cementitious composite.

Three Techniques Used to Produce BaTiO₃Fine Powder

Homogeneous BaTiO3 fine powder has been synthesized at (80°C) by using three different chemical methods using the roots TiCl4, BaCl2 and NaOH or Oxalic acid. The resultant powders were characterized using x-ray diffraction (XRD) to estimate the crystal structure, lattice parameters and the crystallite size to investigate the favor method in producing BaTiO3 fine powder. The criteria that was dependent on considering the favor method that was given better results of XRD and demand a least time in preparation which tend to consume a lowest energy.

Study on Properties of Silver Powder for Maki-e

Maki-e is a traditional Japanese decorative technique that uses the natural lacquer Urushi and metal powders. In 2014, there exist only two companies that manufacture silver powder for the purpose of Maki-e, and this study focuses on comparing the powders manufactured by them. Gloss and color of each silver powder were measured after Maki-e decoration was finished, and EDS (energy-dispersive X-ray spectroscopy) was used to determine the differences in their chemical composition. In addition, to verify the effect of polishing, residual gloss after sulfuration and polishing was measured. The study revealed that the shapes of the silver powders (Maru-fun, No. 1) manufactured by the two companies are different and it affects the occupancy rate of Urushi and powder, which in turn affects their gloss and color. Wakou silver has a very strong resistance to sulfuration;however, owing to its Pd content, its chroma is much lower than that of other powders. It was shown that sulfuration on powder surface can be removed by polishing irrespective of the shape and chemical composition ratio of the particles.

Crystal Structure of Ba_xSr_1-xTiO₃Fine Powder

Various compositions of the system BaxSr1-xTiO3 (BST) have been elaborated both as fine powders and ceramic monoliths, using the co-precipitation route within a warmed supersaturated solution of oxalic acid. The appropriate stoichiometry was determined from the mixtures of precisely titrated aqueous solutions of cations chlorides (SrCl2, BaCl2, and TiCl4). The reason of this process was to apply low sintering temperature in production of BST samples with ultra-fine powders. These powders primarily calcined at (850°C) for (5 hr) were used to elaborate ceramics after pellets sintering at (1200°C) during (8 hrs). Indeed, XRD patterns were confirmed that the samples are a pure phase and a perovskite cubic structural type at (x = 0, 0.5, 0.6). Whereas, (x = 0.7, 0.8, 0.9, 1) showed a tetragonal phase. There is agreement between the FTIR and XRD analysis, by the relation of the wave vector (K) and lattice constant. It was deduced a stimulated relation between (x) and (K). The results of TEM, they were clear that the lowest particle sizes investigated of BST powders nearly (36 - 50 nm).