材料中晶粒尺寸及微观畸变对X衍射线形的影响

讨论了引起X衍射线形宽化的几种因素 ,以及材料中晶粒尺寸的大小、微观畸变与X衍射线形的关系 ,有助于材料工作者在材料性能方面的研究     

高分子网络凝胶法制备纳米ZnO的结构性能研究

采用高分子网络凝胶法制备了ZnO粉末样品。通过X射线衍射、扫描电镜等测试方法研究了样品的物相组成、微观形貌。X射线衍射测试结果显示,样品的衍射峰尖锐,各特征峰显示完整,与标准PDF卡片比对,证实粉末样品的物相为ZnO。使用Scherrer公式计算得到的晶粒度大小约为31.28nm,晶格常数分别为3.247和5.208。使用扫描电镜观测不同放大倍数下的样品形貌,发现晶粒外观形貌显现完整,晶粒尺寸大小与XRD测试结果相吻合。结果表明,实验成功制备了高质量的ZnO纳米多晶粉体,可以用于后续实验。     

纳米粒子的平均晶粒尺寸和晶格畸变的同时测定

本文使用积分宽度法同时确定了纳米CeO2粒子的平均晶粒尺寸和晶格畸变率，讨论了使用X射线衍射数据同时计算纳米粒子的平均晶粒尺寸和晶格畸变的方法，以及应用Gaussian/Cauchy型方程进行数据处理的具体细节，研究结果说明，当计算纳米微晶的晶格畸变时，现有的一些简单计算方法可能使计算出来的晶格畸变值严重失实。     

X-射线全谱拟合法测量钛白粉的晶粒度

采用X射线粉末衍射(XRD)全谱拟合的方法测量了钛白粉样品的晶粒度。选择步进式扫描采谱、结合全谱拟合法程序Topas中的基本参数法(FPA)软件全谱拟合,计算得到晶粒度参数,并与X射线粉末衍射线宽法、扫描电镜(SEM)分析结果进行对比。综合分析认为,X射线全谱拟合法计算钛白粉晶粒度无需标样、操作简便、分析快速准确,可以作为钛白粉的质量控制方法。     

烧结细晶氧化铝陶瓷的新方法

致密的氧化铝陶瓷可用三种方法烧结得到。从SEM照片可看出：样品比较致密,样品的相对密度大于93％．用两步法和两段法烧结得到的氧化铝陶瓷的晶粒尺寸小于400nm,用常规方法烧结得到的氧化铝陶瓷的晶粒尺寸约为650nm。而且,用两步法和两段法烧结时烧结温度低于常规烧结。实验结果表明：两步法和两段法烧结能得到细晶的氧化铝陶瓷。     

SUS430合金连接体La0.8Sr0.2MnO3涂层的制备及微观结构分析

通过对干凝胶粉体的DTA和TG分析探索了La0.8Sr0.2MnO3(LSM)涂层的烧成制度,并采用溶胶-凝胶提拉法制备了SUS430合金LSM涂层.对SUS430/LSM试样进行了X-ray物相分析,确定了样品中的主要物相;通过Rietveld拟合确定了LSM涂层的精细晶体结构;对LSM涂层的XRD峰形宽化进行了分析,计算得到涂层球形晶粒民族尺寸,分析了涂层内部微观应力状况以及微观应力存在的可能原因.     

燃烧反应加压法制备细晶氧化铝陶瓷的致密化机理

采用燃烧反应加压法制备了致密的细晶氧化铝陶瓷。用透射电镜和场发射扫描电镜观察了致密样品,研究了快速升温条件下晶粒尺寸和致密度随烧结时间的变化规律。基于对氧化铝陶瓷致密化过程中晶粒生长动力学及结构形成过程的分析,探讨了燃烧反应加机械压力法制备细晶氧化铝的致密化机理。结果表明:烧结时间在2min以内的时,氧化铝晶粒尺寸没有明显变化,由表面扩散导致的晶粒颈部生长可以忽略。晶粒长大的抑制是由快速的升温速率以及短的烧结时间控制。样品中通过基面位错的滑移和攀移过程在(1120)面上生成具有Burgers矢量为1/3[1010]的层错,致密化过程为晶粒的高温塑性流动及晶界滑移共同作用结果。     

低温烧结NiCuZn铁氧体粉体的制备与磁性能

将化学共沉淀法制备的前驱体直接通入氧气,用氧化法合成NiCuZn铁氧体粉体。通过X射线衍射和扫描电镜分析样品的微观结构和形貌特征,并结合热重–差示扫描量热分析研究样品的晶化过程。用激光粒度仪测量样品的粒度分布曲线,用振动磁强计测量样品室温的磁滞回线,用精密阻抗分析仪测量样品的磁谱。结果表明:NiCuZn铁氧体样品平均晶粒尺寸约为14.9nm,平均颗粒尺寸约为2.37μm,磁化强度为11A.m2/kg。850℃烧结后的相对体积密度达到0.92,起始磁导率为25,截止频率超过110MHz。     

碱式氯化镁结晶性能的研究

本文用电子显微镜及X射线衍射分析方法,对碱式氯化镁Mg_3(OH)_5Cl·4H_2O的晶体生长情况及晶体的微观内应变和晶粒尺寸进行了测定和分析,同时探讨了不同处理过程对晶体结晶性能的影响。研究表明,对晶体进行时化及水热处理,有利于晶体的晶格完善,晶格的微观内应变与处理过程的温度有关,温度愈高,微观内应变愈小。     

热压烧结细晶粒氧化铝陶瓷(英文)

以沉淀法制各的商业α-Al2O3粉体为原料,自制镁铝硅玻璃为烧结助剂,采用热压烧结工艺低温制备高性能氧化铝陶瓷.用Archimedes法、电子探针和三点弯曲法研究了氧化铝陶瓷的致密化行为、显微结构和力学性能.结果表明:在1400℃烧结的氧化铝陶瓷的相对密度高达98.9%,晶粒细小,平均晶粒尺寸约为0.6μm,晶界上有莫来石相析出,样品的抗弯强度和断裂韧性分别达442MPa和4.7MPa·m1/2.     

Microstructural evolution during fabrication of alumina via laser stereolithography technique

Application of additive manufacturing (AM) technology in production of ceramic parts is considered as a state-of-the-art technique which has been recently introduced to industry. In the current study the imperative microstructural characteristics of the alumina manufactured via laser stereolithography (SLA) has been investigated. The microstructural characteristics of the developed ceramic parts and components are still unknown and require detailed investigation. A combination of optical microscopy and scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), image analysis, X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and micro-computed tomography (micro-CT) scans was used to evaluate the microstructural features of the alumina samples after each step of the manufacturing process (i.e. printing, debinding and sintering). In addition, the apparent density of each sample was measured using water displacement method. Results indicated that the porosity of printed alumina samples was significantly reduced after sintering process. EDS analysis confirmed elimination of binder material after debinding and sintering processes. XRD analysis detected existence of α-Al₂O₃ in initial printed samples which was not changed during debinding and sintering processes. Due to detection of identical peaks for all samples, only one set of lattice parameters ($\mathrm{a}$ and $\mathrm{c}$) was calculated from XRD patterns of all samples which was close to the ones reported in literature for alumina. TEM micrographs and corresponding diffraction patterns confirmed polycrystalline structure from different layers of the samples. High resolution transmission electron microscopy (HRTEM) and diffraction patterns from single layers were used to calculate lattice parameters for each sample. A slight increase was noticed in unit cell and grain size after sintering process. The obtained results help for better understanding of the properties through microstructural characteristics of the 3D printed ceramic parts.     

利用Sol-Gel法与水热合成法制备纳米TiO2及其光催化活性研究

以Sol-Gel法及水热合成方法制备了纳米TiO2,利用XRD进行了表征,以太阳光为光源,通过对亚甲基蓝溶液的降解反应,考察了两种方法所得样品的光催化活性。结果表明,利用水热合成法制备的锐钛矿型TiO2具有更小的粒径,而通过溶胶-凝胶制得的样品为混晶型TiO2,对亚甲基蓝降解具有较高的光催化活性。     

Synthesis and Structural Characterization of a Metastable Mullite-Like Alumina Phase

A solution combustion technique for the synthesis of different β-alumina compositions in the Na₂O· x Al₂O₃ system (where x =5, 6, or 7) is described along with the structural characterization of the materials prepared. The amorphous powder obtained after a combustion reaction between the nitrate salts of the cations and aminoacetic acid was calcined in air at different temperatures in the range from 600°C up to 1300°C. The phases were investigated by powder X-ray diffraction (XRD) and infrared spectroscopic measurements. A metastable mullite-like alumina phase was found to form as an intermediate at a minimum calcination temperature of 750°C and stable up to 1000°C, which transformed completely into β/β"-alumina phases beyond a temperature of 1100°C. The crystal structure of the mullite-like alumina phase was deduced by rietveld refinement of slow scan powder XRD data. A better understanding of the crystal structure of the mullite-like alumina was possible using other supplementary experimental evidences.     

Effect of Temperature on Structural and Optical Properties of Boehmite Nanostructure

The nanocrystalline boehmite, γ‐AlOOH, was synthesized by the hydrothermal method using AlCl₃·6H₂O and urea as precursors, and the effect of different annealing temperatures resulting in different phases of alumina (Al₂O₃) was obtained. The effects of different temperature on the phase and micrographs of the prepared γ‐AlOOH nanostructures were investigated. The obtained products were characterized by X‐ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy techniques. The XRD results show that with the increasing temperature, the transformation of boehmite into well‐crystallized α‐Al₂O₃ and the morphology from nanoplatelets with spindle‐like edges to vermicular structure take place. The crystallite size and lattice parameters were calculated by Rietveld refinement. The convincing evidence for the crystal phase of the as‐prepared and annealed samples was provided by FTIR spectra. The Raman spectra unveil the change in vibrational modes of the phase transition alumina.     

纳米Al_20_3的制备及红外吸收研究

用溶胶凝胶法制备了不同晶型和晶粒尺寸的A1203纳米粉末样品,分析了反应过程中各因素对产物形态的影响。对所制得样品的红外吸收能力进行了研究。结果表明,样品的红外吸收能力对其晶型和晶粒尺寸具有一定的依赖性。     

硅酸铋(Bi4Si3O12)晶列结构中的晶粒尺寸和晶粒夹角分布

取向之夹角也服从正态分布,其总体夹角的平均值为122.3°,标准差为11.1°.     

Structural and thermal studies of silver nanoparticles and electrical transport study of their thin films

This work reports the preparation and characterization of silver nanoparticles synthesized through wet chemical solution method and of silver films deposited by dip-coating method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and energy dispersive spectroscopy (EDX) have been used to characterize the prepared silver nanoparticles and thin film. The morphology and crystal structure of silver nanoparticles have been determined by FESEM, HRTEM, and FETEM. The average grain size of silver nanoparticles is found to be 17.5 nm. The peaks in XRD pattern are in good agreement with that of face-centered-cubic form of metallic silver. TGA/DTA results confirmed the weight loss and the exothermic reaction due to desorption of chemisorbed water. The temperature dependence of resistivity of silver thin film, determined in the temperature range of 100-300 K, exhibit semiconducting behavior of the sample. The sample shows the activated variable range hopping in the localized states near the Fermi level.     

Al2O3掺杂方式对Ce0.8Sm0.2O1.9电解质结构和性能的影响

研究了Al2O3掺杂方式对Ce0.8Sm0.2O1.9 (SDC) 材料性能的影响。用XRD、SEM、XEDS和热膨胀系数仪等检测手段对样品的晶体结构、力学、热学、显微结构和微区元素进行检测分析。结果表明：采用低温燃烧一步合成法制备的样品其力学性能、烧结性和离子电导率均优于采用铝溶胶直接添加法所制备的样品,其主要原因在于铝溶胶直接添加法会在SDC材料中产生残留Al2O3,并富集在晶界处形成晶界夹杂,阻碍了氧离子迁移。     

Hot pressing sintering of zinc sulfide microsphere decorated with nanorods synthesized by the simple refluxing method

A zinc sulfide microsphere decorated with nanorods was synthesized using the refluxing method. Then, the as-obtained ZnS nanostructures were consolidated via the hot pressing (HP) technique. X-ray diffraction, Fourier transforms infrared spectroscopy, high-resolution transmission electron microscopy, field emission scanning electron microscopy (FESEM), diffuse reflectance spectroscopy, and X-ray mapping analyzes were used to characterize the ZnS sample. The effects of various factors such as pH, temperature, and reaction time were investigated on the morphology and particle size of ZnS nanostructures. The formation of sphalerite phase of ZnS nanoparticles was confirmed by the XRD analysis. FESEM also revealed that ZnS nanostructures with the molar ratio 1:1.3 (zinc: sulfur) had a spherical morphology decorated with sulfur nanorods. The ZnS nanostructures were consolidated by hot pressing technique at 860 °C for 2h under vacuum atmosphere. XRD analysis indicated that the sintered ceramic had a sphalerite phase. FESEM study demonstrated that ZnS ceramic had a grain size diameter within the range of 1–3 μm.