scholarly journals The Durability of Various Crucible Materials for Aluminum Nitride Crystal Growth by Sublimation

2004 ◽  
Vol 9 ◽  
Author(s):  
B. Liu ◽  
J.H. Edgar ◽  
Z. Gu ◽  
D. Zhuang ◽  
B. Raghothamachar ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Aluminum Nitride ◽  
Niobium Carbide ◽  
Chemical Properties ◽  
Growth Conditions ◽  
Tantalum Carbide ◽  
Vapor Pressures ◽  
Seeded Growth ◽  
Growth Environment ◽  
And Performance

Producing high purity aluminum nitride crystals by the sublimation-recondensation technique is difficult due to the inherently reactive crystal growth environment, normally at temperature in excess of 2100 °C. The durability of the furnace fixture materials (crucibles, retorts, etc.) at such a high temperature remains a critical problem. In the present study, the suitability of several refractory materials for AlN crystal growth is investigated, including tantalum carbide, niobium carbide, tungsten, graphite, and hot-pressed boron nitride. The thermal and chemical properties and performance of these materials in inert gas, as well as under AlN crystal growth conditions are discussed. TaC and NbC are the most stable crucible materials with very low elemental vapor pressures in the crystal growth system. Compared with refractory material coated graphite crucibles, HPBN crucible is better for AlN self-seeded growth, as crystals tend to nucleate in thin colorless platelets with low dislocation density.

INVESTIGATION ON INTERMOLECULAR INTERACTION IN SUPERSATURATION STATE OF CADMIUM SULPHATE MIXED ZINC tris-THIOUREA SULPHATE SOLUTIONS

2014 ◽  
Vol 02 (03n04) ◽  
pp. 1450002 ◽  
Author(s):  
G. G. MULEY ◽  
A. B. NAIK ◽  
A. B. GAMBHIRE
Keyword(s):  
Crystal Growth ◽  
Intermolecular Interaction ◽  
Growth Parameters ◽  
Chemical Properties ◽  
Adiabatic Compressibility ◽  
Growth Conditions ◽  
Ft Ir ◽  
Solid Form ◽  
Physical And Chemical ◽  
And Chemical Properties

Zinc tris-thiourea sulphate (ZTS) is a well known nonlinear optical (NLO) crystal widely used for various NLO applications. The NLO, physical and chemical properties can be modified by adding impurities and/or modifying crystal growth conditions. The impurities present in the growth solution and growth conditions can affect the crystal growth parameters at great extent. Thus, the study on the nature of intermolecular interaction with the dopant in the solution during crystal growth process becomes important. In the present investigation, the ultrasonic velocity was measured in the aqueous solutions of pure and cadmium sulphate mixed ZTS in the supersaturation state at 313.15 K. The thermodynamic parameters such as adiabatic compressibility, inter molecular free length, acoustic impedance and relative associations have been calculated from the ultrasonic data and densities of water and solutions at 313.15 K, and the nature of intermolecular interaction has been discussed. FT-IR spectra of all mixtures in the solid form at room temperature were recorded and the shifts in the absorption peaks corresponding to the functional groups of ZTS have been reported.

Nanocrystals: The Preparation, Precise Control and Application Toward the Pharmaceutics and Food Industry

2018 ◽  
Vol 24 (21) ◽  
pp. 2425-2431 ◽  
Author(s):  
Cao Wu ◽  
Zhou Chen ◽  
Ya Hu ◽  
Zhiyuan Rao ◽  
Wangping Wu ◽  
...  
Keyword(s):  
Food Industry ◽  
Chemical Properties ◽  
Preparation Methods ◽  
Precise Control ◽  
Significant Process ◽  
Technology Applications ◽  
And Performance ◽  
Physical And Chemical ◽  
Analytical Technology ◽  
And Chemical Properties

Crystallization is a significant process employed to produce a wide variety of materials in pharmaceutical and food area. The control of crystal dimension, crystallinity, and shape is very important because they will affect the subsequent filtration, drying and grinding performance as well as the physical and chemical properties of the material. This review summarizes the special features of crystallization technology and the preparation methods of nanocrystals, and discusses analytical technology which is used to control crystal quality and performance. The crystallization technology applications in pharmaceutics and foods are also outlined. These illustrated examples further help us to gain a better understanding of the crystallization technology for pharmaceutics and foods.

Néel temperature of zinc-blende, MBE-grown MnTe layers: modification by the crystal growth conditions

2004 ◽  
Vol 1 (4) ◽  
pp. 953-956 ◽  
Author(s):  
W. Szuszkiewicz ◽  
E. Dynowska ◽  
J. Z. Domagala ◽  
E. Janik ◽  
E. Łusakowska ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Growth Conditions ◽  
Neel Temperature ◽  
Néel Temperature ◽  
Zinc Blende

Bulk laser damage of large-size KDP crystals obtained at various crystal growth conditions

1994 ◽  
Author(s):  
Marina I. Kolybayeva ◽  
Igor M. Pritula ◽  
Viacheslav M. Puzikov ◽  
Vitaly I. Salo ◽  
Serge V. Garnov ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Growth Conditions ◽  
Laser Damage ◽  
Large Size ◽  
Kdp Crystals

scholarly journals Testing Engine Oil Specifications and Properties and its Effects on the Engines Maintenance and Performance

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Chemical Properties ◽  
Mechanical Tests ◽  
Engine Oil ◽  
Strong Relation ◽  
Degree Of Stability ◽  
And Performance ◽  
The Cost ◽  
Motor Oils ◽  
Physical And Chemical ◽  
And Chemical Properties

This paper presents the results of practical mechanical tests of motor oils, their specifications and characteristics and the effect of their physical and chemical properties on the performance of the engine. The performance of the engine has a strong relation with the engine oil type and efficiency. The degree of stability of oils properties is very important because if oil or lubricants lose their properties, mechanical and chemical excessive corrosion of the motor metals may occur. Consequently, damage occurs to one or more parts of the engine, thereby the system is breaking down where the cost of downtime is too expensive. It has been found that a higher viscosity value is not the optimum as it increases temperature and energy consumption due to frictional losses. The values required for viscosity is the ideals that gives the stable results regardless temperature variations under any conditions of operation, at which the power losses are minimal and the fuel economy is optimal.

scholarly journals BCG Substrains Change Their Outermost Surface as a Function of Growth Media

Vaccines ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 40
Author(s):  
Sandra Guallar-Garrido ◽  
Farners Almiñana-Rapún ◽  
Víctor Campo-Pérez ◽  
Eduard Torrents ◽  
Marina Luquin ◽  
...  
Keyword(s):  
Culture Media ◽  
Chemical Properties ◽  
Growth Conditions ◽  
Neutral Red ◽  
Culture Conditions ◽  
Host Cells ◽  
Growth Media ◽  
Phenotypic Characteristics ◽  
Outermost Surface ◽  
Red Dye

Mycobacterium bovis bacillus Calmette-Guérin (BCG) efficacy as an immunotherapy tool can be influenced by the genetic background or immune status of the treated population and by the BCG substrain used. BCG comprises several substrains with genetic differences that elicit diverse phenotypic characteristics. Moreover, modifications of phenotypic characteristics can be influenced by culture conditions. However, several culture media formulations are used worldwide to produce BCG. To elucidate the influence of growth conditions on BCG characteristics, five different substrains were grown on two culture media, and the lipidic profile and physico-chemical properties were evaluated. Our results show that each BCG substrain displays a variety of lipidic profiles on the outermost surface depending on the growth conditions. These modifications lead to a breadth of hydrophobicity patterns and a different ability to reduce neutral red dye within the same BCG substrain, suggesting the influence of BCG growth conditions on the interaction between BCG cells and host cells.

Temperature-modulated crystal growth and performance for highly reproducible and efficient perovskite solar cells

2017 ◽  
Vol 19 (20) ◽  
pp. 13147-13152 ◽  
Author(s):  
Tongyu Su ◽  
Xinhang Li ◽  
Yongzhuan Zhang ◽  
Fapei Zhang ◽  
Zhigao Sheng
Keyword(s):  
Solar Cells ◽  
Crystal Growth ◽  
Perovskite Solar Cells ◽  
And Performance

The Ta effect on a perovskite precursor combining amorphous PbI2 and CH3NH3I was studied and the best PCE of 17.61% was achieved.

A New Approach Using Artificial Substrates for Growth of High-Quality Precipitate-Free HTS Thin Films, Toward Electronic Device Applications

2005 ◽  
Vol 868 ◽  
Author(s):  
K. Endo ◽  
P. Badica ◽  
H. Sato ◽  
H. Akoh
Keyword(s):  
Thin Films ◽  
Electronic Device ◽  
Growth Conditions ◽  
Device Fabrication ◽  
Artificial Substrates ◽  
High Quality ◽  
New Approach ◽  
Mesa Structure ◽  
Device Applications ◽  
And Performance

AbstractHigh quality thin films of HTS have been grown by MOCVD on substrates with artificial steps of predefined height and width. The surface of the films grown on the steps having width equal to the ‘double of the migration length' of the atomic species depositing on the substrate is totally free of precipitates: precipitates are gathered at the step edges where the free energy is lowest. The method has several advantages: it is simple, universal (it is independent of the materials, substrates, deposition technique or application) and allows control of precipitates segregates so that the quality and growth conditions of the films are the same as for the films grown on conventional substrates. The method is expected to result in new opportunities for the device fabrication, design and performance. As an example we present successful fabrication of a mesa structure showing intrinsic Josephson effect. We have used thin films of Bi-2212/Bi-2223 superstructure grown on (001) SrTiO3 single crystal substrates with artificial steps of 20 μm.

Autonomy of differentiation in avian branchial somites and the influence of adjacent tissues

Development ◽  
1987 ◽  
Vol 100 (3) ◽  
pp. 449-462 ◽  
Author(s):  
T. Kenny-Mobbs ◽  
P. Thorogood
Keyword(s):  
Chorioallantoic Membrane ◽  
Growth Conditions ◽  
Explant Culture ◽  
Developmental Pathways ◽  
Morphological Evidence ◽  
Growth Environment ◽  
Enzymatic Dissociation ◽  
Time Migration ◽  
Recombination Experiments ◽  
Do So

This study investigates the differentiative abilities of avian brachial somites at stages of development before, during and after the migration of somitic cells into the wing primordium. These somites are the source of cells that migrate into the forelimbs and there give rise exclusively, and totally, to the skeletal muscle lineage of the wing and yet show no morphological evidence of commitment to that fate when they leave the somites. The aim of the study was to see if the brachial somitic cells are committed to particular developmental pathways at these stages. The brachial somites were isolated from HH stage-12, -15 and -18 chick embryos, either by microdissection or enzymatic dissociation, and grown in organ culture, in explant culture on different substrata or on the chorioallantoic membrane (CAM) of host chicks, either alone or in combination with adjacent tissues. Myogenesis and chondrogenesis occurred in all stage-18 enzymatically separated somites, regardless of the growth environment. Myogenesis was reduced in stage-15 somites and unobservable in stage-12 somites; however, recombination of stage-12 somites with epithelium or neural tube increased the incidence of myogenesis at this stage. The incidence of chondrogenesis was also less in the younger explants. Unlike its effect on myogenic expression, recombination with epithelium resulted in a dramatic decrease in chondrogenesis in both stage-12 and -15 somites. The recombination experiments suggest that conditions that maintain the normal spatial relationships within isolated somites permit expression of a preexisting specification to a particular fate. They also show that the overlying epithelium can inhibit chondrogenesis in these somites. Overall, the results suggest that by the time migration of somitic cells into wing regions is finishing, brachial somitic cells have become stabilized in their ability to undergo both myogenesis and chondrogenesis for they will do so under a variety of growth conditions and independently of adjacent tissues. However, immediately before (stage 12) and shortly after (stage 15) the onset of migration, both myogenic and chondrogenic expression by brachial somitic cells are still under the influence of interactions with adjacent tissues.

scholarly journals Recent Results in the Crystal Growth of GaN at High N2 Pressure

1996 ◽  
Vol 1 ◽  
Author(s):  
I. Grzegory ◽  
M. Bockowski ◽  
B. Lucznik ◽  
S. Krukowski ◽  
M. Wroblewski ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Growth Direction ◽  
Layer Growth ◽  
Seeded Growth ◽  
Bulk Crystal Growth ◽  
Bulk Gan ◽  
Experimental Solubility Data ◽  
Stable Growth ◽  
Image Position ◽  
Homoepitaxial Layers

We present recent results on bulk GaN crystallization. The best quality GaN crystals grown from the solution at high N2 pressure without an intentional seeding are single crystalline platelets of stable morphology reaching dimensions up to 10 mm. The fastest growth direction for such crystals is [1 0 0], perpendicular to the GaN c-axis. The maximum stable growth rate perpendicular to crystal c-axis is determined from the experiment and used for an estimate of the effective supersaturation for the {10 0} face assuming two dimensional layer growth. The heat of GaN disssolution, determined from experimental solubility data, is used for the estimation of the edge energy of 2-D nuclei on the growing {10 0} face. Bulk crystal growth seeded by a single hexagonal needle with well developed {10 0} faces is also reported. The crystallization mechanisms and morphological stability in seeded growth of GaN are discussed on the basis of experimental results. The physical properties of the GaN crystals and homoepitaxial layers grown on them are briefly reviewed.

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