The relation between the atomic structure and the macroscopic properties and behaviors of a material constitute one of the objectives of the materials science, particularly in the design and development of ceramic mat...The relation between the atomic structure and the macroscopic properties and behaviors of a material constitute one of the objectives of the materials science, particularly in the design and development of ceramic materials.Crystalline and non crystalline phases together with pores, grain boundaries, etc. affect mechanical and fracture properties as well as chemical resistance and electric properties. These aspects will be bonded to the raw materials chosen and the whole processing route.In glass industry, although there are other electrofused refractories such as the alumina ones used in the feeding of the fusion kilns, probably the most used refractories in contact with the melted glass are electrofused materials that belong to the Al2O3-SiO2-ZrO2 system commonly named AZS.Exceptionally for refractory materials the amount of the glassy phase in a AZS material is important and appreciable;and makes them particularly adequate for containing fussed glass. The glass proportion will define much of their properties and behaviors.In the present work the results of the non crystalline phase quantification of two samples of commercial AZS materials are presented and compared. These were obtained by three different methods using in the X ray powder diffraction (XRD) techniques. The first method consists in the linear interpolation of the base lines of the diffractograms compared to the amorphous silica and the fully crystalline quartz. The other two methods are based in the application of the Rietveld method. One is the internal standard method with quartz as fully crystalline standard and the other one consist in the inclusion of the glassy phase to the refinement with a structural model that can be understood as the widening of the peaks consequence of an extreme decrease in the crystallite size of a quartz phase.The three methods showed equivalent results (with differences less than 3%) for the two samples and demonstrated that are adequate for the quantification of the non crystalline phase in this kind of materials.展开更多
目前XRD内标法定量相分析存在标样难以获取、成本高,试验过程不一致导致不同实验室测试结果没有可比性等问题。针对该问题,笔者提出以晶体结构数据为依据,通过理论计算获得XRD内标法定量相分析的标准曲线来进行定量分析。并在Philips X...目前XRD内标法定量相分析存在标样难以获取、成本高,试验过程不一致导致不同实验室测试结果没有可比性等问题。针对该问题,笔者提出以晶体结构数据为依据,通过理论计算获得XRD内标法定量相分析的标准曲线来进行定量分析。并在Philips X’Pert Pro MPD衍射仪上用刚玉等5种标准样品进行了实际测试验证,结果表明该方法具有可行性。最后在此基础上提出建立XRD内标法定量相分析标准曲线库的设想和具体的方案。展开更多
Nanometer Zn particles with mean diameters 12-100nm made by evaporating its powders in argon gas were studied mainly by X-ray diffraction and electron microscopy. They are collected at various distances and those fact...Nanometer Zn particles with mean diameters 12-100nm made by evaporating its powders in argon gas were studied mainly by X-ray diffraction and electron microscopy. They are collected at various distances and those factors influencing the mean particle size were studied. The optimal synthetic conditions were obtained, i.e., evaporation temperature is 1200℃; argon flow rate is 0.4m3/h; amount of powder charged is 3g; distance from evaporation source is 10cm. It was found that the size of particles was governed by argon flow rate, evaporation temperature, amount of metal charged and distance from the source. The size increases remarkably with distance in the space where no metal vapor exists. This implies that the crystallites grow by coalescence. Electron micrographs and diffraction patterns are reproduced to show the size, shape and state of oxidations. Nanoparticles with definite crystal habits were sometimes observed among those with irregular ones.展开更多
Nanocrystalline ZnO thin films have been fabricated by a multi-step solgel method using spin coating technique. Zinc acetate dihydrate, 2-methoxyethanol and monoethanolamine were used as a starting material, solvent a...Nanocrystalline ZnO thin films have been fabricated by a multi-step solgel method using spin coating technique. Zinc acetate dihydrate, 2-methoxyethanol and monoethanolamine were used as a starting material, solvent and stabilizer, respectively. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were employed to characterize structure and morphologies of the as-deposited samples. The results of XRD and SEM showed that the heat treatment conditions, final rotational (spinning) speed, fume exhaust and precise control of concentration of reactants (precursor and solvent used) strongly affect the crystallographic orientation and morphology of the resultant ZnO films. The XRD pattern showed that the ZnO films formed the preferred orientation along c-axis and the grain size is 16nm for the samples. Only one peak corresponding to the (002) plane at 2θ = 34.34 appears on the diffractograms. The as-deposited films had a transparency of greater than 80% in the visible-near IR region from 400 nm - 800 nm. The optical band gap energy and thickness were calculated to be 3.296 eV and 266 nm respectively.展开更多
文摘The relation between the atomic structure and the macroscopic properties and behaviors of a material constitute one of the objectives of the materials science, particularly in the design and development of ceramic materials.Crystalline and non crystalline phases together with pores, grain boundaries, etc. affect mechanical and fracture properties as well as chemical resistance and electric properties. These aspects will be bonded to the raw materials chosen and the whole processing route.In glass industry, although there are other electrofused refractories such as the alumina ones used in the feeding of the fusion kilns, probably the most used refractories in contact with the melted glass are electrofused materials that belong to the Al2O3-SiO2-ZrO2 system commonly named AZS.Exceptionally for refractory materials the amount of the glassy phase in a AZS material is important and appreciable;and makes them particularly adequate for containing fussed glass. The glass proportion will define much of their properties and behaviors.In the present work the results of the non crystalline phase quantification of two samples of commercial AZS materials are presented and compared. These were obtained by three different methods using in the X ray powder diffraction (XRD) techniques. The first method consists in the linear interpolation of the base lines of the diffractograms compared to the amorphous silica and the fully crystalline quartz. The other two methods are based in the application of the Rietveld method. One is the internal standard method with quartz as fully crystalline standard and the other one consist in the inclusion of the glassy phase to the refinement with a structural model that can be understood as the widening of the peaks consequence of an extreme decrease in the crystallite size of a quartz phase.The three methods showed equivalent results (with differences less than 3%) for the two samples and demonstrated that are adequate for the quantification of the non crystalline phase in this kind of materials.
文摘目前XRD内标法定量相分析存在标样难以获取、成本高,试验过程不一致导致不同实验室测试结果没有可比性等问题。针对该问题,笔者提出以晶体结构数据为依据,通过理论计算获得XRD内标法定量相分析的标准曲线来进行定量分析。并在Philips X’Pert Pro MPD衍射仪上用刚玉等5种标准样品进行了实际测试验证,结果表明该方法具有可行性。最后在此基础上提出建立XRD内标法定量相分析标准曲线库的设想和具体的方案。
文摘Nanometer Zn particles with mean diameters 12-100nm made by evaporating its powders in argon gas were studied mainly by X-ray diffraction and electron microscopy. They are collected at various distances and those factors influencing the mean particle size were studied. The optimal synthetic conditions were obtained, i.e., evaporation temperature is 1200℃; argon flow rate is 0.4m3/h; amount of powder charged is 3g; distance from evaporation source is 10cm. It was found that the size of particles was governed by argon flow rate, evaporation temperature, amount of metal charged and distance from the source. The size increases remarkably with distance in the space where no metal vapor exists. This implies that the crystallites grow by coalescence. Electron micrographs and diffraction patterns are reproduced to show the size, shape and state of oxidations. Nanoparticles with definite crystal habits were sometimes observed among those with irregular ones.
文摘Nanocrystalline ZnO thin films have been fabricated by a multi-step solgel method using spin coating technique. Zinc acetate dihydrate, 2-methoxyethanol and monoethanolamine were used as a starting material, solvent and stabilizer, respectively. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were employed to characterize structure and morphologies of the as-deposited samples. The results of XRD and SEM showed that the heat treatment conditions, final rotational (spinning) speed, fume exhaust and precise control of concentration of reactants (precursor and solvent used) strongly affect the crystallographic orientation and morphology of the resultant ZnO films. The XRD pattern showed that the ZnO films formed the preferred orientation along c-axis and the grain size is 16nm for the samples. Only one peak corresponding to the (002) plane at 2θ = 34.34 appears on the diffractograms. The as-deposited films had a transparency of greater than 80% in the visible-near IR region from 400 nm - 800 nm. The optical band gap energy and thickness were calculated to be 3.296 eV and 266 nm respectively.
