精确测定单晶点阵参数的一种方法

基于透镜形花样的球面三角理论，提出了分析透射点发散Ｘ－Ｒａｙ花样的新理论即虚晶面理论．通过分析发现：目前通用的透镜形花样的球面三角理认仅为虚晶面理论的一个推论，亦即虚晶面理论包括了透镜花样的球面三角理论     

从电子衍射谱测定晶体取向关系的快速分析法

从电子衍射谱测定晶体取向关系的方法,过去都是用极图描点法借助于吴氏网进行手工操作。本文提出一种快速分析法,取向分析的全部过程由计算机自动完成,且准确、直观。它适用于各大晶系和点阵。经过多次运用,证明该方法是行之有效的。     

Reactions of bis(3-aminopropyl)amine with formaldehyde in the presence of a metal ion: Preparation of a metal-free macropolycycle and a dinuclear copper(II) complex

The reaction of bis(3-aminopropyl)amine with excess formaldehyde in the presence of Ni²⁺ ion produces the macropentacyclic compound L¹(ClO₄)₂ (1) L¹ = 1,3,7,11,13,17- hexaazapentacyclo[15.3.1.1^3.7.1^7.13.1^13.17]tetracosane). The dinuclear complex [Cu₂(L²)₂(H₂O)₂](ClO₄)₂ (2) (HL¹ = 1-(3-aminopropyl)-3-(hydroxymethyl)-1,3-diazacyclohexane) as well as 1 can be prepared by the condensation reaction in the presence of Cu²⁺ ion. Interestingly, 2 · 2H₂O exhibits uncommon magnetic behavior.     

硅灰石球磨过程中晶体结构的变化

研究了湖北大冶硅灰石精矿粉经不同时间刚玉球干磨后,晶体结构的变化特点。初期以多型转变为主,后期以晶体结构破坏为主,晶格畸变效应贯穿变化的全过程。在球磨过程中晶粒的剥离方向并不总是平行于{100}解理方向而是变化的,变化的剥离方向平行于晶体结构中单四面体的某些边棱方向。     

Field emission properties and growth mechanism of In2O3 nanostructures

Four kinds of nanostructures, nanoneedles, nanohooks, nanorods, and nanotowers of In₂O₃, have been grown by the vapor transport process with Au catalysts or without any catalysts. The morphology and structure of the prepared nanostructures are determined on the basis of field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM). The growth direction of the In₂O₃ nanoneedles is along the [001], and those of the other three nanostructures are along the [100]. The growth mechanism of the nanoneedles is the vapor-liquid–solid (VLS), and those of the other three nanostructures are the vapor-solid (VS) processes. The field emission properties of four kinds of In₂O₃ nanostructures have been investigated. Among them, the nanoneedles have the best field emission properties with the lowest turn-on field of 4.9 V/μm and the threshold field of 12 V/μm due to possessing the smallest emitter tip radius and the weakest screening effect.     

Growth mechanisms of MgO nanocrystals via a sol-gel synthesis using different complexing agents

In the preparation of nanostructured materials, it is important to optimize synthesis parameters in order to obtain the desired material. This work investigates the role of complexing agents, oxalic acid and tartaric acid, in the production of MgO nanocrystals. Results from simultaneous thermogravimetric analysis (STA) show that the two different synthesis routes yield precursors with different thermal profiles. It is found that the thermal profiles of the precursors can reveal the effects of crystal growth during thermal annealing. X-ray diffraction confirms that the final products are pure, single phase and of cubic shape. It is also found that complexing agents can affect the rate of crystal growth. The structures of the oxalic acid and tartaric acid as well as the complexation sites play very important roles in the formation of the nanocrystals. The complexing agents influence the rate of growth which affects the final crystallite size of the materials. Surprisingly, it is also found that oxalic acid and tartaric acid act as surfactants inhibiting crystal growth even at a high temperature of 950°C and a long annealing time of 36 h. The crystallite formation routes are proposed to be via linear and branched polymer networks due to the different structures of the complexing agents.     

Preparation and characterization of single crystalline In2O3 films deposited on MgO (110) substrates by MOCVD

Epitaxial indium oxide (In₂O₃) films have been prepared on MgO (110) substrates by metal-organic chemical vapor deposition (MOCVD). The deposition temperature varies from 500 °C to 700 °C. The films deposited at each temperature display a cube-on-cube orientation relation with respect to the substrate. The In₂O₃ film deposited at 600 °C exhibits the best crystalline quality. A clear epitaxial relationship of In₂O₃ (110)|MgO (110) with In₂O₃ [001]|MgO [001] has been observed from the interface area between the film and the substrate. The average transmittance of the prepared films in the visible range is over 95%. The band gap of the obtained In₂O₃ films is about 3.55–3.70 eV.     

Particle Size Control and Crystal Habit Modification of Phenacetin Using Ultrasonic Crystallization

Power ultrasound is applied for cooling crystallization to control and modify the particle size and crystal habit of an active pharmaceutical ingredient, phenacetin. Operating parameters including sonication intensity and duration, solution concentration, and cooling rate are studied and compared. With respect to mean particle size, the effect of sonication intensity is most significant. In addition, the crystal habit of recrystallized phenacetin is modified substantially and shows an elliptic shape. Recrystallized phenacetin also provides an enhanced dissolution rate compared with the original sample. These results prove that ultrasonic crystallization is an efficient tool for controlling the solid‐state properties of an active pharmaceutical ingredient.     

Synthesis,microstructure and electromechanical properties of undoped (K0·5Na0·5)NbO3

Conventional solid state mixed oxide route using manual and ball milling is investigated for the preparation of K_0·5Na_0·5NbO₃ (KNN) ceramics. Microstructure engineering was made using two milling methods and sintering techniques, and the crystal growth; then electromechanical properties were investigated as a function of sintering temperature, densification and grain size. The sintering conditions were set at 920°C/5 min for spark plasma sintering and 1090–1120°C/10 and 48 h for classical sintering. KNN crystal was grown using floating zone technique under nitrogen gas, where the translation and rotation speeds were fixed at 3 mm h^?1 and 20 rev min^?1 respectively. Piezoelectric and dielectric performances were measured and related to the microstructure. High k_t (33 to 48%), k_p of 18 to 48% and d₃₃ of 127–140 pC N^?1 were reached for relative densities of 84 to 96%. KNN ceramics are now available for the design of ultrasonic sensors.     

奥克托今转晶研究

采用α－ＨＭＸ为原料，以醋酐法工艺的废酸为溶剂，溶解α－ＨＭＸ和在废酸中氧化α－ＨＭＸ的所含杂质，运用升降温冷却结晶技术，进行转晶取得成功。并摸索出制备中等粒度级别的工艺条件，产品酸度均小于或等于０．０２％，熔点大于或等于２７３℃。为醋酐法制备ＨＭＸ生产工艺的改进和降低ＨＭＸ生产成本奠定了基础。