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.

Crystal structural refinement for NdAlSi

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.

Chemical Composition and Crystal Structure of the Eggshell of the Green Crested Lizard Bronchocela cristatella(Agamidae)

The majority of extant reptiles are oviparous and produce eggs with three major components:embryo,yolk,and eggshell.The eggshell is species-specific and more diverse in squamate reptiles than in other amniote taxa.Here,we study the crystal structure,chemical composition,and bonding states of the eggshell of the green crested lizard Bronchocela cristatella.X-ray diffractometer(XRD)analysis showed the existence of two clearly defined and distinguishable crystalline phases,aragonite and calcite.Using the XRD data and a unit cell refinement routine,we identified two sets of cell parameters:a=4.956 A,b=7.965 A,and c=5.734 A for the aragonite phase;a=4.987 A,b=4.987 A,and c=17.056 A for the calcite structure.We used x-ray photoelectron spectroscopy to examine detailed elemental composition and bonding states and found that the eggshell was composed primarily of elements C,N,Ca,and O,with C,N and O bonded to various types of hybridization in the protein of the eggshell membrane.The Ca:C:O ratio for the calcium carbonate yielded a value of-7:8:21,which is close to the expected stoichiometric value of CaCO3.

Crystal Growth and Properties of Co^(2+) doped Y_3Sc_2Ga_3O_(12) Single Crystal

Single crystal of cobalt (Co)-doped Y3Sc2Ga3O12 (YSGG) with the dimensions up to Φ20×40 mm3 and undoped YSGG crystal with the dimensions up to Φ28×60 mm3 have been grown using the Czochralski technique. The structure of the crystal was characterized by the X-ray powder diffraction (XRPD) method. The absorbance spectra of the crystal shows that it has strong absorption bands at 606 and 1540 nm. The results indicate that the crystal Y3Sc2Ga3O12 may be a kind of good Q-switch material.

The crystal structures and physical properties of the solid solution compound Ba_5Y_(8-x)Mn_4O_(21-1.5x)(x = 0,1)

New oxometallides with the formula Ba5Y8-xMn4021-1.5x （x = 0, 1） are prepared through an atmosphere-controlled solid-state reaction. Two single-phase samples with Ba/Y/Mn atomic ratios 5/8/4 （Y8） and 5/7/4 （Y7） are obtained. The crystal structures and the physical properties of the compounds are investigated by X-ray powder diffraction, magnetization, conductivity, and dielectricity measurements. The Ba5Y8-xMn4021-1.5x compound is demonstrated to be a Y-deficient solid solution. The solid solution compound Ba5Y8-xMn4021-1.5x crystallizes into tetragonal symmetry with the space group I4/m. Detailed structure analysis by Rietveld refinement of the X-ray powder diffraction data reveals that the Y vacancies occur preferentially at the Y（2） site. Thermal magnetization measurements indicate the presence of antiferromagnetic interaction between Mn ions in the compounds, and temperature-dependent resistivity measurements show that insulator-semiconductor transitions occur around 175 K and 170 K for the Y8 and Y7 samples, respectively. Strong frequency dependences of the dielectric constant are observed above -175 K for the two compounds.

CRYSTAL DATA AND ASSIGNMENT OF POWDER X-RAY DIFFRACTION PATTERN OF 107 K SINGLE SUPERCONDUCTING PHASE IN Pb-Bi-Sr-Ca-Cu-O SYSTEM

In the Bi-Sr-Ca-Cu-O superconductor system, two superconducting phases (85K and 105K) were found by Maeda et al. By substituting Pb, enhanced superconducting properties and structure stabilization in these compounds have been reported. Recently, the

The determination of the crystal struoure of tetra-potassium uranyl tricarbonate by powder X-ray diffraction method

A uranyl compound, K_4UO_2(CO_3)_3 has been characterized by powder X-ray diffraction method. M. W.=606.46, monoclinic, C2/c (No. 15), a=1.0240(7), b=0.9198(4), c=1.2222(12)nm, β=95.12(4)°,V=1.1466(5)nm^3, Z=4, D_m=3.468g/cm^3, D_c=3.513g/cm~, λ(Cu Kα_1)=O.1540598nm, T=298K. The structure was solved by heavy atom method and Fourier synthesis, and refined by full- matrix least-squares method to R=0.1185 for 275 reflections. The uranium (Ⅵ) atom is in an eight-coordinate distorted hexagonal-bipyramidal environment with creasy fan shape. The linear uranyl group approaches to perpendicular to the equatorial plane in which three carbonate groups are chelated. U(Ⅵ) has two linear oxygen atoms closer to it (U-O=0.1767 (5) nm) than six other neighbours (U-O ranging from 0.2516 to 0.2568nm). The distances between carbon atoms and uncoordinated oxygen atoms are 0.122 (1) and 0.123(1) nm, which are distinctly different from those between carbon and coordinated oxygen atoms (mean 0.134(6) nm). This fact reveals the non-eq- uivalence of one oxygen atom to the other two in each carbonate. In K_4UO_2(CO_3)_3, the O-O dis- tance for the adjacent carbonate groups is 0.2794(4)nm approaching to the sum of Van der Waals radii of two oxygen atoms. The K-O distances vary between 0.2667 and 0.3131nm, and each anion is immediately surrounded by six potassium ions, only four of which can be considered to belong to the same structural formula unit, and they are symmetrically located above and below the equatorial plane.

金刚石热稳定性研究

通过热处理、酸处理实验，利用Ｘ－ｒａｙ 衍射、发射光谱分析、ＸＴＬ－ Ⅱ显微观察对合成金刚石进行了较系统的研究。结果表明：粉末触媒合成金刚石杂质含量少，强度高，热稳定性要好，并指出缺陷、杂质组成、含量及存在形式是影响金刚石热稳定性、强度的重要因素。杂质的大量存在导致金刚石的热稳定性急剧下降，温度为１１００ ℃时，尤为明显。

应用SEM-EDX和PXRD分析生活饮用水中水垢成分及其赋存形态——以某城市一供水点生活饮用水为例

探明饮用水中水垢成分及赋存形态对于评价和保障饮用水水质量具有重要的意义.本研究首次联用扫描电镜-能谱仪(SEM-EDS)和粉晶X射线衍射仪(PXRD)定性分析了生活饮用水中水垢成分及其赋存形态.SEM-EDS分析显示:水垢中的主要元素有C、O、Si、S、Mg、Ca、Fe和Zn以及少量的Cl、Cu、Co、Cr和V元素,生活饮用水中悬浮物(SS)有B、C、O、Na、Al、Si、S、P、Ti、Mg、K、Ca、Mn、Fe和Zn等元素,水中溶解性总固体(TDS)中有C、O、Si、S、Cl、Na、Mg和Ca等元素;PXRD进一步分析显示:水垢中的晶体成分是CaSO_(4)·2H_(2)O和CaCO_(3)·H_(2)O;TDS中含有Ca^(2+)、SO_(4)^(2-)、HCO_(3)^(2-)、Mg^(2+)、Na^(+)、Cl^(-)和可溶性SiO_(2),以Ca^(2+)和SO_(4)^(2-)为主,HCO_(3)^(2-)次之.基于以上分析表明:Ca^(2+)、SO_(4)^(2-)、HCO_(3)^(2-)是参与结垢的主要离子,C、O、Si、S、Mg、Ca、Fe和Zn元素是参与结垢的主要元素.所提出的方法可更全面地探明生活饮用水中的主要结垢成分,从而为生活饮用水水质分析提供了一种新的技术依据.

Structural and Magnetic Properties in Nd_(0.7)Sr_(0.3)MnO_3 Manganite

The temperature evolution of the crystal structure for Nd_(0.5)Sr_(0.5)MnO_3 has been investigated by powder XRD between 125 Kand 725K.The structure can be described with a monoclinic symmetry(space group P21/m)in the temperature range of 125—175 K,while with the increase in temperature between 175 Kand 575 Kthe structure involves a higher orthorhombic symmetry(space group Imma).The rhombohedral structure with space group R-3cis observed at high temperature region of 575—725K.The increase in the magnetization at low temperatures can be ascribed to the field-induced short-range magnetic order of the Nd3+ions.The dc and ac susceptibility data show some anomalies around the FM-PM transition region which can be attributed to the glass behavior and magnetic relaxation.

Temperature-dependent structure and magnetization of YCrO_(3)compound

We have grown a YCrO_(3)single crystal by the floating-zone method and studied its temperature-dependent crystalline structure and magnetization by x-ray powder diffraction and PPMS DynaCool measurements.All diffraction patterns were well indexed by an orthorhombic structure with space group of Pbnm(No.62).From 36 K to 300 K,no structural phase transition occurs in the pulverized YCrO_(3)single crystal.The antiferromagnetic phase transition temperature was determined as T_(N)=141.58(5)K by the magnetization versus temperature measurements.We found weak ferromagnetic behavior in the magnetic hysteresis loops below TN.Especially,we demonstrated that the antiferromagnetism and weak ferromagnetism appear simultaneously upon cooling.The lattice parameters(a,b,c,and V)deviate downward from the Grüneisen law,displaying an anisotropic magnetostriction effect.We extracted temperature variation of the local distortion parameterΔ.Compared to theΔvalue of Cr ions,Y,O1,and O2 ions show one order of magnitude largerΔvalues indicative of much stronger local lattice distortions.Moreover,the calculated bond valence states of Y and O2 ions have obvious subduction charges.

Rietveld Refinement of New Solid Solution Al_xSb_ ( 3-x)Y_5 (0≤x≤2.16)

The X-ray diffraction analyses show that the existence of a continuous solid solution of Al_xSb_ 3-xY_5 (0≤x≤216). Al_xSb_ 3-xY_5 crystallizes in the hexagonal system with the space group P6_3/mcm (193) and Mn_5Si_3 structure type. The cell parameters for Al_2SbY_5 compound at 25 ℃ are a=0.88086 (2) nm, c=0.64662 (2) nm.

Syntheses，Structures and Properties of Some New Composition Perovskite Compounds：Sr0．6Bi0．4FeO2．7，Sr1－xBixFeO3－y and Ba1．5Pt0．5Mn2O6

New composition perovskite-type compounds with formula Sr0.6Bi0.4FeO2.7,Sr1-xBixFeO3-y(x=0.1 to 0. 9 in interveral of 0.1),and Ba1.5Pt0.5Mn2O6 have been synthsized and structurally characterized.The crystal structure of Sr0.6Bi0.4FeO2.7has been determined by X-ray single crystal diffraction,and the data of neutron powder diffraction collected at both room temperature and elevated temperature(380℃).The compound Sr0.6Bi0.4FeO2.7 crystallizes in the cubic space group of Pm3m with Z=1,a=3.9330(6) at room temperature,a=3.9498(6)A at 380℃.The magnetic structure from the neutron powder diffraction data collected at room temperature is consistent with a simple G-type antiferromagnetism and has a magnetic moment of 4.98 μB per Fe atom.The structures of Sr1-xBixFeO3-y with x other than 0.4 were also refined from the X-ray powder diffraction data.The data were consistent with a tetragonal cell when x=0.1,a rhombohedral cell when x= 0.9,and a cubic cell for x=0.2～0.8.From single crystal X-ray diffraction data,Ba1.5Pt0.5Mn2O6 crystallizes in hexagonal space group of P63mc with a= 5.7722 (6),c=4.4504(9),V=128.42(2),Z=1.The Sr(1-x)BixFeO(3-y)are found to be a good electronic and ionic conductor.

Synthesis and crystal structure of SrNi_xV_(6-x)O_(11)

THE AV6O11（A,alkaline or alkaline earth metals）-type compounds are the only phases