(Bi2O3)1-x(Sc2O3)x(x=0.01,0.03,0.05)粉末晶体的制备与晶体结构分析

采用固相烧结法制备(Bi2O3)1-x(Sc2O3)x(x=0.01, 0.03, 0.05)粉末晶体,在室温下对几种样品分别进行了X射线衍射实验,并用RIETAN-2000程序中的Rietveld解析法以及VEND、PRIMA和VICS程序分别研究了几种样品的晶体结构、等高电子密度（2D和3D）、原子配位数及原子热振动各向同性因子B等. 结果表明,(Bi2O3)1-x(Sc2O3)x(x=0.01, 0.03, 0.05)的晶胞体积（分别为329.3399Å3、329.5016 Å3、329.3400 Å3、330.3658 Å3）比Bi2O3的晶胞体积（330.3658 Å3）小;(Bi2O3)1-x(Sc2O3)x(x=0.01, 0.03, 0.05)晶体的原子热振动各向同性温度因子B(Sc1)、B(Sc2)、B(Bi1)、B(Bi2)、B(O1)、B(O2)、B(O3)的大小分别为0.42883 Å2、0.54412 Å2、0.609364 Å2、0.502542 Å2、0.4034 Å2、0.61406 Å2、0.74259 Å2;0.43052 Å2、0.52778 Å2、0.51647 Å2、0.382431 Å2、0.320327 Å2、0.516762 Å2、0.76875 Å2和0.42347 Å2、0.61022 Å2、0.514476 Å2、0.302724 Å2、0.34725 Å2、0.56175 Å2、0.72125 Å2. 确定了(Bi2O3)1-x(Sc2O3)x(x=0.01, 0.03, 0.05)粉末晶体属于单斜晶系,实现了二维和三维等高电子密度分布的可视化,进一步确定了晶体结构和原子位置.     

采用Rietveld精修方法解析粉末晶体MgF2、SrF2的原子热振动

分别在室温（25℃）和高温（300℃）下,通过X射线衍射实验对MgF2和SrF2晶体进行了晶体结构的检测．利用基于Rietveld精修方法的RIETAN－2000程序对所得实验结果进行了解析,精修了MgF2和SrF2晶体在不同温度下的各晶体结构参数,获得了原子各向同性温度因子B．通过Maximum Entropy Meth-od （ MEM）解析得到了MgF2和SrF2晶体的等高电子密度分布图谱,实现了电子密度分布的可视化．     

采用Rietveld精修方法解析粉末晶体MgF2、SrF2的原子热振动

分别在室温（25℃）和高温（300℃）下,通过X射线衍射实验对MgF2和SrF2晶体进行了晶体结构的检测。利用基于Rietveld精修方法的RIETAN-2000程序对所得实验结果进行了解析,精修了MgF2和SrF2晶体在不同温度下的各晶体结构参数,获得了原子各向同性温度因子B。通过Maximum Entropy Method (MEM) 解析得到了MgF2和SrF2晶体的等高电子密度分布图谱,实现了电子密度分布的可视化。     

氧化钇粉末晶体的原子热振动

利用GN-2型高能球磨机研磨了Y_2O_3粉末晶体,用BT-1600图像颗粒分析仪对研磨时间为0h和20h的两份样品进行了分析.室温条件下,利用X射线衍射实验检测了晶体结构的变化,并且利用RIETAN-2000程序进行了晶体结构精修得到了原子热振动的大小.运用MEM解析方法实现了2D(平面)和3D(立体)的等高电子密度分布的可视化.     

Lal-xTexMnO3晶格结构的X射线粉末衍射分析

通过X射线粉末衍射数据,用Rietveld精修方法分析了Te部分替换LaMnO3中La后,其晶格参数及其结构对称性所发生的变化.结果表明:Te掺杂LaMnO3系列样品具有R(3)C的晶格结构对称性,其MnO6八面体晶格还产生了伸张畸变,畸变程度随Te掺杂量的增加而增大.此外根据Mn-O-Mn键角、eg电子能带的带宽、A位离子平均半径及A位离子尺寸失配度等的变化特点,推测Te掺杂LaMnO3样品除居里温度等相变物理量将随x增加而非线性变化外,还可能产生自旋玻璃态、相分离等宏观现象.     

La1-xTexMnO3晶格结构的X射线粉末衍射分析

通过X射线粉末衍射数据,用Rietveld精修方法分析了Te部分替换LaMnO₃中La后,其晶格参数及其结构对称性所发生的变化.结果表明：Te掺杂LaMnO₃系列样品具有R3C的晶格结构对称性,其MnO₆八面体晶格还产生了伸张畸变,畸变程度随Te掺杂量的增加而增大.此外根据Mn—O—Mn键角、e_g电子能带的带宽、A位离子平均半径及A位离子尺寸失配度等的变化特点,推测Te掺杂LaMnO₃样品除居里温度等相变物理量将随x增加而非线性变化外,还可能产生自旋玻璃态、相分离等宏观现象.关键词：庞磁电阻效应La-Te-Mn-OX射线衍射Rietveld精修     

X射线衍射研究Bi2Sr2—yMyCuO6＋δ（M=La,Pr）晶体结构

作报道了用Ｘ射衍射法对Ｂｉ２Ｓｒ２－ｙＭｙＣｕＯ６＋δ（Ｍ＝ＬａＰｒ０．０＜ｙ＜１．０）系列单晶样品进行结构的研究，根据晶体结构的不同性质，我们将掺杂区分为三个区域，第一个区域的掺镧量在０．０＜ｙ＜０．１０之间，在此区域中晶体的平均结构为单斜结构，其调制波矢具有两个非公度分量ｑ＝βｂ＋γｃ，第二个掺杂区的掺镧量在０．１０＜ｙ＜０．６０之间，晶体的平均结构由单斜转变为正交结构，调制波矢具有单个非公     

(Nd1-x Erx)3 Fe25 Cr4.0(0≤x≤1.0)化合物的结构与磁性

合成了 (Nd1 -xErx) 3Fe2 5Cr4 . 0 (0≤x≤ 1 .0 )系列化合物并采用x射线衍射和磁测量等手段研究了它们的结构和磁性 .发现当 0≤x≤ 0 . 8时化合物保持Nd3(Fe,Ti) 2 9型结构 ,属于单斜晶系 ,A2 m空间群 ,当 0 8相似文献   

The crystal structures and physical properties of the solid solution compound Ba5Y8-xMn4021-1.5x （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.     

基于La_(1.4)Ca_(1.6)Mn_2O_7结构、电输运及磁性研究(英文)

我们制备了名义成分是La1.4 Ca1.6 Mn2 O7的多晶样品,并且研究了它的结构、磁性和电性.利用Rietveld方法对X射线衍射数据进行精修的结果表明,该La1.4 Ca1.6 Mn2 O7是由钙钛矿锰氧化物La0.66 Ca0.34 MnO3和氧化钙CaO组成的复相混合物.其中,La0.66 Ca0.34 MnO3占相成分的大部分,而CaO占小部分.我们对比了该名义组分样品La1.4 Ca1.6 Mn2 O7和La0.7 Ca0.3 MnO3的铁磁居里转变温度和绝缘体-金属转变温度,结果表明该La1.4 Ca1.6 Mn2 O7的磁输运性质是由其中的钙钛矿相成分决定的.所有的这些结果表明,名义组分样品La1.4 Ca1.6 Mn2 O7实际上并没有形成所谓的Sr3Ti2O7型的双层结构,而实际形成的是以钙钛矿结构作为主相的复相混合物.     

New ferromagnetic La3Co2TaO9 double perovskite: Structural and magnetic properties

The new double perovskite La₃Co₂TaO₉ has been prepared by a solid-state procedure. The crystal and magnetic structures have been studied from X-ray powder diffraction (XRPD) and neutron powder diffraction (NPD) data. Rietveld refinements were performed in the monoclinic space group P2₁/n. The structure consists of an ordered array of alternating B′O₆ and B″O₆ octahedra sharing corners, tilted along the three pseudocubic axes according to the Glazer notation a⁻b⁻c⁺. Rietveld refinements show that at RT the cell parameters are a=5.6005(7) Å, b=5.6931(7) Å, c=7.9429(9) Å and β=89.9539(7)°, and the refined crystallographic formula of this “double perovskite” can be written as La₂(Co)_2d(Co_1/3Ta_2/3)_2cO₆. Magnetization measurements and low-temperature NPD data show that the perovskite is a ferromagnet with T_C=72 K. At high T it follows the Curie–Weiss law with an effective magnetic moment of 3.82μ_B per Co ion which is very close to spin only Co²⁺ (HS).     

Effect of Ba and Ho co-doping on crystal structure,phase transformation,magnetic properties and dielectric properties of BiFeO3

Multiferroics having composition Bi_0.80-xBa_0.20Ho_xFeO₃ (BBFO, BBHFO5, BBHFO10, BBHFO15 and BBHFO20 for x?=?0.0, 0.05, 0.10, 0.15 and 0.20 respectively) were synthesized by method of solid state reaction. The crystal structure has been studied using X-ray diffraction technique. The X-ray patterns show enormous transform in crystal structure at concentration x?=?0.20. The Rietveld refinement of XRD patterns indicates that at concentration x?=?0.0 sample have rhombohedral structure with R3c space group while for the concentration x?=?0.05, 0.10, 0.15 and 0.20, the mixed phase including rhombohedral R3c and triclinic P1 space groups were obtained with best fitting. This phase transformation in crystal structure is observed due to mismatching of ionic radii of doped ions and parent ions. Magnetic properties of all samples were carried out by using vibrating sample magnetometry. M-H hysteresis loops shows that with doping of Ba and Ho antiferromagnetic BiFeO₃ (BFO) transforms into ferromagnetic. The dielectric and ferroelectric measurements were carried out which shows that dielectric constant, dielectric loss and ferroelectric properties are enhanced with co-doping of Ho in comparison of the pristine BFO due to structure deformation and decrease in oxygen vacancies with higher concentration of Ho. Significant improvement has been observed in dielectric constant and remnant magnetization values with increasing content of Ho and decrease in the dielectric loss.     

Structure change analysis in γ-Fe2O3/carbon composite in the process of electrochemical lithium insertion

It was previously shown that γ-Fe₂O₃/carbon composite synthesized by the aqueous solution method exhibit good high-speed charge/discharge and cycle characteristics as the cathode material in lithium-ion rechargeable batteries. We examined the crystal structure of γ-Fe₂O₃ in γ-Fe₂O₃/carbon composite by X-ray diffraction and the Rietveld analysis before and during electrochemical insertion of lithium ions. Before insertion, the sample has a spinel structure belonging to the Fd3¯m space group with the following iron occupancies: 8a site, 0.92, 16c site, 0 and 16d site, 0.87. During insertion, iron occupancy at 16d site remains virtually constant, at 8a site decreases from 0.92 to 0, and at 16c site increases from 0 to 0.53. These results suggest that, during insertion, iron migrates from 8a to 16c site. In the most highly lithiated sample, iron occupancy at 8a site decreases to 0 and occupancies at 16c and 16d sites were not equalized. Thus, the crystal structure for this sample belongs not to the Fm3¯m space group that represents the rock salt structure, but rather to the Fd3¯m space group.     

X射线衍射法检测氰化钾

建立X射线衍射仪检测氰化钾的方法。与传统分析方法相比,该方法具有简便、快速、准确以及不破坏样品的特点。