A new metal-organic crystal: Potassium thiourea chloride

The growth and characterization of a new nonlinear metal-organic crystal, potassium thiourea chloride (PTC), is reported. The growth of single crystals of PTC was accomplished by the slow evaporation solution growth method. Single crystal X-ray diffraction analysis confirms the crystal structure. The FT-IR analysis confirms the presence of sulfur to potassium bonds in the complex. From the optical spectrum PTC has a good optical transmission in the entire visible region, which is an essential requirement for a nonlinear crystal.     

Controllable growth of Se nanotubes and nanowires from different solvent during the sonochemical process

Selenium (Se) nanotubes and nanowires have been controllably prepared by a solution-phase approach consisting of hydrothermal process and subsequent sonochemical process in different solvent including methanol, ethanol, acetone, dimethyl formamide, water, isopropanol and ethylene glycol. It is revealed that the formation of the Se nanotubes or nanowires is dependent on the breakage or not of the in-situ generated Se nanoparticles. The effects of the solvents on the morphology of Se nanostructures have been preliminarily discussed. Finally, Se nanotubes and nanowires have been characterized by X-ray powder diffraction (XRD), field emission scan electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy.     

C_(60)单晶生长的优化研究

用晶体生长动力学考察了籽晶法气相生长C60单晶体的生长工艺，得出关键在于处理成核与长大两个因素之间的矛盾。对管状炉的温度场进行了重新设计，将冷端的最低温度点移至合适部位，有效地控制了成核的数目。通过不断地优化实验，经选出恰当的冷、热端温度及生长周期，生长出的C6。单晶的最大钱度超过6mm，且有较高的结晶品质。同一单晶的劳厄像显示出C60的生长暴露面有（111）和（100）两种。     

A new method to evaluate the quality of single crystal Cu by an X-ray diffraction butterfly pattern method

A new method for the evaluation of the quality of an Ohno continuous cast (OCC) Cu single crystal by X-ray diffraction (XRD) butterfly pattern was brought forward. Experimental results show that the growth direction of single crystal Cu is inclined from both sides of the single crystal Cu rod to the axis and is axially symmetric. The degree of deviation from the [100] orientation from the crystal axis is less than 5° with a casting speed 10–40 mm/min. The orientation of single crystal Cu does not have a fixed direction but is in a regular range. Moreover, the orientation of stray grains in the single crystal Cu is random from continuous casting.     

Development and validation of a two-dimensional population balance model for a supercritical CO2 antisolvent batch crystallization process

In this study, a two-dimensional population balance model with solvent removal kinetics has been developed to predict the dynamic behavior of carbamazepine form II crystals produced by a supercritical CO₂ antisolvent batch crystallization process. The model was simulated and validated using experimental crystal size distribution data (CSD). The model was able to accurately predict the behavior of CSD with a change in process operating conditions. The model was also applied to study the time evolution of aspect ratio, average crystal length, and solute concentration in the solution. Finally, solvent removal kinetics were modeled to evaluate the solvent content and drying temperature of the drying gas during the solvent removal process. The developed mathematical model and the presented results suggest the ability of the discussed approach to make suitable model predictions, which can significantly reduce the number of experimental trials required for process design, optimization, and control.     

Growth of hexagonal selenium crystals: Observation of new growth morphologies

In this communication, we report the single crystal growth of selenium by the solution method. We have observed a new mesh-like growth pattern in hexagonal selenium for the first time. Crystals having hexagonal morphology are packed together like hay stick bunches.     

Release Property of Progesterone from a Mixed-Base Suppository Consisting of Witepsol® W35 and Witepsol® E85

The mechanism of drug release from progesterone suppositories that consist of two types of hard fat (Witepsol® W35 and Witepsol® E85) was investigated. The strength, the thermodynamic characteristics, the surface structures, the drug release property, methylene blue penetration into suppositories, and change of surface structure after the dissolution test were employed for detecting characteristics of progesterone suppositories. The formulation with a mixing ratio of Witepsol W35 and Witepsol E85 at a 1:1 ratio showed the maximum strength value. The peak temperature of the suppositories showed a tendency to increase with increases in the ratio of Witepsol E85. The maximum height of the profiles measured with laser microscopy, from 20.8 μm to 29.2 μm, reached a maximum after 3 h of the dissolution test. When the suppositories were immersed in pH 7.4 phosphate buffer containing 0.5% methylene blue at 37°C, the penetrating area increased with time. The weight of the suppositories also increased with time. According to these findings, it was suggested that the release of drug from a mixed type of suppository containing progesterone was via the matrix and pores.     

Mesocrystals: a new class of solid materials

Possible types of, and formation mechanisms for, mesocrystals are summarized. Mesocrystals are a new class of solid materials, which can be regarded as assemblies of crystallographically oriented nanocrystals. Mesocrystals have high crystallinity as well as high porosity, making them promising substitutes for single-crystalline and/or porous polycrystalline materials in many applications such as catalysis, sensing, and solar-energy conversion.     

Growth and characterization of new oxide and fluoride crystals for optical applications

High quality oxide and fluoride single crystals for optical applications have been grown by the Czochralski technique. Lattice parameter investigation of grown Gd₃Yb _x Ga_5−x O₁₂ suggested that this crystal will be a superior material as substrate for optical isolators with large Faraday effect. Growth conditions of (La,Sr)(Al,Ta)O₃ single crystals are discussed. These crystals have excellent lattice matching with GaN, a promising material for optoelectronic devices. Ce-doped fluoride single crystals—LiCaAIF₆, LiYF₄ and BaLiF₃—have been grown for solid state UV laser applications. Growth results and optical characterization are discussed.     

Growth and optical properties of (Yb3−xYx)Al5O12:Ce single crystals

To improve the infrared emission of Yb³⁺ ions doped in the garnet host Y₃Al₅O₁₂ (YAG) single crystal through the energy transfer from Ce³⁺ to Yb³⁺ ions, the 〈1 1 1〉-oriented YAG:Ce³⁺, YAG:Yb³⁺, YAG:(Ce³⁺, Yb³⁺) and Yb₃Al₅O₁₂:Ce³⁺ (YbAG:Ce³⁺) single crystals were grown using the Czochralski Method, respectively. The excitation and emission spectra of these garnet single crystals were characterized. In YAG:Ce³⁺ crystal, the yellow emission of Ce³⁺ ions present, but it was completely extinguished in YAG:(Ce³⁺, Yb³⁺) crystal and YbAG:Ce³⁺ crystal. However, the characteristic absorption bands of Ce³⁺ still existed in the excitation spectrum of Yb³⁺ ions, which showed that the energy absorbed by Ce³⁺ ions can be transferred to Yb³⁺ ions for its infrared emission.     

Synthesis,crystal structure and thermal analysis of a new stilbazolium salt crystal

A new organic crystal of 4-N, N-dimethylamino-4′-N′-methyl-stilbazolium benzene sulfonate (DASBS) was synthesized and characterized for the first time. It is a derivative of 4-N, N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST) with the benzene sulfonate replacing p-toluenesulfonate. Single crystal XRD demonstrated that the crystal structure of DASBS·H₂O was triclinic. The thermal analysis of this new crystal was also conducted, and the melting point was obtained to be 232°C.     

Nano-hybrid shish-kebab: Isotactic polypropylene epitaxial growth on electrospun polyamide 66 nanofibers via isothermal crystallization

Polyamide 66 (PA 66) nanofibers, with the mean diameter of about 140 nm, were prepared by electrospinning. Nano-hybrid shish-kebab (NHSK) structure was achieved in PA 66 nanofibers/isotactic polypropylene (iPP) composites via isothermal solution crystallization. The morphology of such NHSK was observed by scanning electron microscopy (SEM). It was found that PA 66 nanofibers act as “shish”, and iPP crystals serve as “kebabs”. Furthermore, the concentration of iPP solution remarkably affects the morphology of the NHSK, i.e., the size of iPP crystals becomes much bigger with the increasing iPP solutions' concentration. The reason for this can be explained as that the high concentration of iPP solutions contain more free chains which can participate into the process of crystallization.     

Growth and characterization of dexterous nonlinear optical material: Dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol (DMAPNP)

The crystals (dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol [DMAPNP] suitable for NLO applications were grown by the slow cooling method. The solubility and metastable zone width measurement of DMAPNP specimen was studied. The material crystallizes in the orthorhombic crystal system with noncentrosymmetric space group of P2₁2₁2_1. The ocular precision in the intact visible region was found to be good for non-linear optical claim. Quality of the grown crystal is ascertained by the HRXRD and etching studies. Laser Damage Threshold and Photoluminescence studies designate that the grown crystal contains less imperfection. The mechanical behaviour of DMAPNP sample at different temperatures was investigated to determine the hardness stability of the grown specimen. The piezoelectric temperament and the relative Second Harmonic Generation (for diverse particle sizes) of the material were also studied. The third order nonlinear optical properties of DMAPNP crystals were premeditated by Z-scan method. Birefringence and optical homogeneity of the crystal were evaluated using modified channel spectrum method. The half wave voltage of the grown crystal deliberate from the elector optic experimentation. Photoconductivity measurement specified consummate of inducing dipoles owing to brawny incident radiation and also disclose the nonlinear activities of the grown specimen.     

A novel approach to fabrication of fullerene C60 nanotubes: Using C60-pyridine colloid as a precursor

A novel approach to rapid fabrication of fullerene C₆₀ nanotubes (FNTs) has been developed using C₆₀-pyridine colloid as a precursor. The colloid was prepared by exposing a C₆₀-pyridine solution to visible light. Without irradiation of the visible light, growth of FNTs is not found in the freshly prepared C₆₀-pyridine solution and the ultrasound-agitated solution. By contrast, the FNTs were easily grown in the C₆₀-pyridine solution which was exposed to the visible light. The observation of the Tyndall effect indicated the formation of C₆₀-pyridine colloid that is essential for synthesizing the FNTs with excellent reproducibility. The results showed that the wall of FNTs was a local face-centered cubic crystal arrangement.     

Synthesis of MoO3 nanoplates from a metallorganic molecular precursor

Orthorhombic phase MoO₃ nanoplates were synthesized directly by thermolysis of an air-stable metallorganic molecular precursor (molybdenum diethyldithiocarbamate oxide: Mo((C₂H₅)₂NCS₂)₂O₂, which was prepared simply through the precipitation reaction of ammonium peramolybdate and sodium diethyldithiocarbamate in distilled water under the ambient condition) in air at 350-400 °C for 5 h. The control experiments with ammonium peramolybdate as precursor could only obtain mostly irregular microcrystallites, indicating that the metallorganic molecular precursor, Mo((C₂H₅)₂NCS₂)₂O₂ played an important role in the successful synthesis of MoO₃ nanoplates.     

Synthesis ZnO nanoparticles from a new Zinc(II) coordination polymer precursor

A new zinc(II) nitrite coordination polymer, [Zn(3-bpdh)(NO₂)₂]_n (1), 3-bpdh = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene} was prepared and characterized by elemental analyses and IR spectroscopy. Compound 1 was structurally characterized by single-crystal X-ray diffraction and is one-dimensional polymer with coordination environment of distorted octahedral, ZnN₂O₄. Thermal decomposition of this precursor in oleic acid at 240 °C under air atmosphere results in the formation of nanoparticles of ZnO. The nano-materials were characterized by scanning electron microscopy, X-ray powder diffraction (XRD) and IR spectroscopy. The thermal stability of nano-structure ZnO was studied by thermal gravimetric and differential thermal analyses and showed that there is no reportable loss of weight in the TGA curves that proves the existence of zinc(II) oxide. This study demonstrates the coordination polymers may be suitable precursors for the preparation of nanoscale materials.     

氟化物激光晶体Nd3+:LiYF4的坩埚下降法生长

本文报道了氟化物激光晶体Ｎｄ＾３＋：ＬｉＹＦ４的坩埚埚下降法生长工艺,采用经氟化处理的无水氟化物原料,按照ＬｉＦ：ＹＦ３＝５１５：４８．５的比例配料,控制炉体温度于９２０－９６０℃,晶体生长速度为０．４－０．８ｍｍ／ｈ,通过密闭条件下的坩埚下降法生长出尺寸为φ２５ｍｍ＊８０ｍｍ的完整单晶。     

Nanostructured tellurium semiconductor: from nanoparticles to nanorods

Selective fabrication of single crystalline tellurium nanorods of various lengths and spherical nanoparticles can be easily achieved by a simple hydrothermal reduction method. The product was characterised by X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction and energy-dispersive X-ray spectroscopy techniques. It was found that when the concentration of orthotelluric acid gradually increased from 4 to 10, 20, 30 and 50?mM with other conditions controlled, the morphology of the tellurium nanocrystals gradually changed from long nanorod to shorter nanorods and eventually became spherical. Based on the experimental results, the morphology control mechanism of tellurium nanocrytals was well reasoned.     

氟化物激光晶体 Nd3+:LiYF4的坩埚下降法生长

本文报道了氟化物激光晶体Ｎｄ３＋： ＬｉＹＦ４的坩埚下降法生长工艺．采用经氟化处理的无水氟化物原料,按照 ＬｉＦ： ＹＦ３＝ ５１．５： ４８．５的比例配料,控制炉体温度于 ９２０～９６０℃,晶体生长速度为 ０．４～０．８ ｍｍ／ｈ,通过密闭条件下的坩埚下降法生长出尺寸为 ４２５ｍｍ×８０ｍｍ的完整单晶．