Crystal growth and morphology of hindered phenol AO-60

Crystal growth of a hindered phenol compound, tetrakis [methylene-3-(3-5-ditert-butyl-4-hydroxy phenyl) propionyloxy] methane (trade name AO-60), was successfully recorded by optical microscopy (OM) equipped with a hot stage. The morphology of AO-60 crystals, grown at 100 °C from amorphous state, appeared in the form of tetragonal-sloped step growth. Further study using scanning electron microscopy (SEM) and atomic force microscopy (AFM) experimentally demonstrated that AO-60 crystals had a hopper-like morphology, which had occurred rarely in the condition of organic compound crystals but predominantly rather to inorganic compound crystals in the reported literatures. The morphological features observed on the crystal surfaces suggested step growth and hopper growth mechanism. Besides, a raising around the edge of the AO-60 hopper crystal was also experimentally characterized for the first time.     

Synthesis,growth mechanism and optical characterization of zinc nitride hollow structures

In this report, we describe the noncatalytic and template-free synthesis of zinc nitride (Zn₃N₂) novel microstructures with hollow interiors via simple nitridation reaction of zinc powder at optimum temperature of 600° C for 120 min in ammonia gas environment under atmospheric pressure. Hollow microstructures obtained were mostly of spherical shape with diameters in the range 8–35 μm and with open mouth on the surface. The growth mechanism has been proposed for the elucidation of hollow structures formation. Crystal structure and phase purity of the product were investigated by X-ray diffraction (XRD) characterization and energy dispersive X-ray spectroscopy (EDS) analysis confirmed the chemical composition of the product. Morphology of the as-prepared product was investigated using scanning electron microscopy (SEM). Ultraviolet–visible–near infrared (UV–vis–NIR) spectrophotometry was used to study the transmittance behaviour of zinc nitride microstructures and thereby an indirect optical band gap of 2.81 eV was calculated using Davis–Mott model. Room temperature photoluminescence (PL) studies exhibited two prominent peaks of the product; one very strong peak near band edge UV emission (395 nm) and other comparatively suppressed and broad peak at orange luminescence emission (670 nm).     

GaP:Mg layers grown on GaN by MOCVD

We have investigated the growth of magnesium-doped GaP (GaP:Mg) layers on GaN by metalorganic chemical vapor deposition. The hole carrier concentration increased linearly from 0.8×10¹⁸ to 4.2×10¹⁸ cm⁻³ as the Bis(cyclopentadienyl) magnesium (Cp₂Mg) mole flow rate increased from 1.2×10⁻⁷ to 3.6×10⁻⁷ mol/min. However, the hole carrier concentration decreased when the CP₂Mg mole flow rate was further increased. The double crystal X-ray diffraction (DCXRD) rocking curves showed that the GaP:Mg layers were single crystalline at low CP₂Mg molar flow. However, the GaP:Mg layers became polycrystalline if the CP₂Mg molar flow was too high. The decrease in hole carrier concentration at high CP₂Mg molar flow was due to crystal quality deterioration of the GaP layer, which also resulted in the low hole mobility of the GaP:Mg layer.     

Polar dependence of impurity incorporation and yellow luminescence in GaN films grown by metal-organic chemical vapor deposition

We have investigated the unintentional impurities, oxygen and carbon, in GaN films grown on c-plane, r-plane as well as m-plane sapphire by metal-organic chemical vapor deposition. The GaN layer was analyzed by secondary ion mass spectroscopy. The different trend of the incorporation of oxygen and carbon has been explained in the polar (0 0 0 1), nonpolar (1 1 2¯ 0) and semipolar (1 1 2¯ 2) GaN by a combination of the atom bonding structure and the origin direction of the impurities. Furthermore, it has been found that there is a stronger yellow luminescence (YL) in GaN with higher concentration of carbon, suggesting that C-involved defects are originally responsible for the YL.     

定容高压气体的压缩因子

１前言压缩因子是比较实际气体与理想气体之差异的重要物理量，从某状态的压缩因子Ｚ可求出该状态下实际气体的Ｐ或Ｖ来。现在高压气体的Ｚ大多是在高压ＰＶＴ实验台上用定容测试方法（绝对法）测试出来。但测试过程耗时费资，在新型气态工质不断涌现的今天，一些特殊高压高温条件很难在实验中满足；而工程上则多从对比态原理出发，从两参量或三参量的普遍化压缩因子图中近似求出，显然，其系统误差一般较大，一般说来，高压气体的Ｚ是系统温度Ｔ，压力Ｐ和偏心因子。的函数Ｚ＝Ｚ（Ｔ，Ｐ），其解析形式一直是热物性工作者努力探求的目标，…     

三层介质长圆柱界面上极化电荷和磁化电流的分立镜像

计算表明，三层介质无工圆柱界面上的极化电荷和磁化电流可用多个分立镜像代替，从而使电场和磁场的计算更简单和直观。