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Sample records for crystal growth furnace

  1. Adaptive temperature profile control of a multizone crystal growth furnace

    Science.gov (United States)

    Batur, C.; Sharpless, R. B.; Duval, W. M. B.; Rosenthal, B. N.

    1991-01-01

    An intelligent measurement system is described which is used to assess the shape of a crystal while it is growing inside a multizone transparent furnace. A color video imaging system observes the crystal in real time, and determines the position and the shape of the interface. This information is used to evaluate the crystal growth rate, and to analyze the effects of translational velocity and temperature profiles on the shape of the interface. Creation of this knowledge base is the first step to incorporate image processing into furnace control.

  2. Studies of laser crystal growth. 1. Production of crystal growth furnaces and operating results

    International Nuclear Information System (INIS)

    Sugiyama, Akira; Sasuga, Tsuneo; Arisawa, Takashi; Takuma, Hiroshi; Anzai, Yutaka; Katsurayama, Masamichi; Yamazaki, Takafumi; Yamagishi, Kiyoshi.

    1997-10-01

    Table top short pulse Peta-watt laser system is the most promising light source to drive studying high energy field physics in advance photon research. To achieve high efficiency laser oscillation in stable condition, it is required to pull out the best performance from laser crystals as the gain medium. Therefore, we have conducted cooperative investigation with Mitsui Mining and Smelting Co., LTD. to create large ideal laser crystals by improved growth methods which solve several problems in usual growth techniques. This report describes specifications, results of operation, and improvements in two different types of growth furnaces which make homogeneous doped concentration along growth direction of Nd:YAG laser crystal and large fluoride laser crystals with a wide band gap, respectively. It also describes the first four results of crystals such as YAG, Nd:YAG, YLF, and LBO grown by these furnaces. (author)

  3. A numerical model including PID control of a multizone crystal growth furnace

    Science.gov (United States)

    Panzarella, Charles H.; Kassemi, Mohammad

    1992-01-01

    This paper presents a 2D axisymmetric combined conduction and radiation model of a multizone crystal growth furnace. The model is based on a programmable multizone furnace (PMZF) designed and built at NASA Lewis Research Center for growing high quality semiconductor crystals. A novel feature of this model is a control algorithm which automatically adjusts the power in any number of independently controlled heaters to establish the desired crystal temperatures in the furnace model. The control algorithm eliminates the need for numerous trial and error runs previously required to obtain the same results. The finite element code, FIDAP, used to develop the furnace model, was modified to directly incorporate the control algorithm. This algorithm, which presently uses PID control, and the associated heat transfer model are briefly discussed. Together, they have been used to predict the heater power distributions for a variety of furnace configurations and desired temperature profiles. Examples are included to demonstrate the effectiveness of the PID controlled model in establishing isothermal, Bridgman, and other complicated temperature profies in the sample. Finally, an example is given to show how the algorithm can be used to change the desired profile with time according to a prescribed temperature-time evolution.

  4. Automatic Control System for the High Pressure CdTe Crystal Growth Furnace

    Directory of Open Access Journals (Sweden)

    Petr Praus

    2006-08-01

    Full Text Available CdTe and (CdZnTe bulk single crystals have been widely used as substrates for MBE and LPE epitaxy of infrared (HgCdTe as well as gamma- and X-ray detectors. The Cd1-xZnxTe (x = 0.04-0.1 single crystals with diameter up to 100 mm and height at most 40 mm were prepared in our laboratory in a vertical arrangement by gradual cooling of the melt (the Vertical Gradient Freezing method. Achievement of excellent crystal quality required full control of Cd pressure during the growth process and application of high Cd pressures (up to 4 bar at growth temperature. An electronic control system was designed to control both temperature and internal pressure of two zones CZT crystal growth furnace by using two high performance PID controllers/setpoint programmers. Two wire current loop serial communication bus was used for the data exchange and computer control of the furnace electronics setup. Control software was written to supervise the crystal growth process and to collect all important data and parameters.

  5. High-Precision Temperature Control of a Crystal Growth Furnace at 1,500 C

    Science.gov (United States)

    Stenzel, Ch.; Hess, A.; Croell, A.; Breuer, D.; Sauermann, H.

    2012-01-01

    For crystal growth of semiconductor materials a short-term temperature stability of 0.1 C at 1500 C is one of the essential parameters to be addressed for achieving high-quality crystals. Hence, for temperature monitoring and control with high precision in a floating zone furnace two sets of thermo-sensors, type B thermocouples and optical fibre thermometers, have been implemented and successfully operated in the furnace for more than 2000 h. The optical fibre thermometers consist of an optical system made of sapphire (two fibres plus a prism in between for deflection) and transmit the infra-red radiation of the heater to the outside of the hot core of the furnace for pyrometric temperature measurement. A dedicated control algorithm has been set up which controlled the power settings to the individual heaters. Both sensor types showed no degradation after this period and yielded a short-term stability at 1200 C of 0.05 C (optical fibre thermometers), respectively 0.08 C (thermocouples).

  6. Effects of furnace temperature profile on the interface shape during Bridgman crystal growth

    Science.gov (United States)

    Taghavi, K.; Duval, W. M. B.

    1988-01-01

    The effects of asymmetry in furnace temperature profile and pulling velocity on the crystal interface shape are demonstrated while neglecting the latent heat of solidification. It is concluded that the furnace temperature profile may be varied in order to influence the interface shape of the crystal. An exact thermal analysis is performed on the Bridgman technique by including the latent heat of solidification as a source term. The exact temperature field is obtained for the case of a flat melt-crystal interface. The earlier observation regarding the influence of furnace temperature profile on the crystal interface shape is confirmed and a criterion for a flat crystal interface is obtained. Various furnace temperature profiles are selected and their corresponding results are presented.

  7. Adaptive control of interface by temperature and interface profile feedback in transparent multi-zone crystal growth furnace

    Science.gov (United States)

    Batur, Celal

    1991-01-01

    The objective of this research is to control the dynamics of multizone programmable crystal growth furnaces. Due to the inevitable heat exchange among different heating zones and the transient nature of the process, the dynamics of multizone furnaces is time varying, distributed, and therefore complex in nature. Electrical power to heating zones and the translational speed of the ampoule are employed as inputs to control the dynamics. Structural properties of the crystal is the ultimate aim of this adaptive control system. These properties can be monitored in different ways. Following an order of complexity, these may include: (1) on line measurement of the material optical properties such as the refractive index of crystal; (2) on line x-ray imaging of the interface topology; (3) on line optical quantification of the interface profile such as the determination of concavity or convexity of the interface shape; and (4) on line temperature measurement at points closest to the material such as measurements of the ampoule's outside and inside surface temperatures. The research performed makes use of the temperature and optical measurements, specified in (3) and (4) as the outputs of furnace dynamics. However, if the instrumentation is available, the proposed control methodology can be extended to the measurements listed in (1) and (2).

  8. Controllable Growth of Monolayer MoS2 and MoSe2 Crystals Using Three-temperature-zone Furnace

    Science.gov (United States)

    Zheng, Binjie; Chen, Yuanfu

    2017-12-01

    Monolayer molybdenum disulfide (MoS2) and molybdenum diselenide (MoSe2) have attracted a great attention for their exceptional electronic and optoelectronic properties among the two dimensional family. However, controllable synthesis of monolayer crystals with high quality needs to be improved urgently. Here we demonstrate a chemical vapor deposition (CVD) growth of monolayer MoS2 and MoSe2 crystals using three-temperature-zone furnace. Systematical study of the effects of growth pressure, temperature and time on the thickness, morphology and grain size of crystals shows the good controllability. The photoluminescence (PL) characterizations indicate that the as-grown monolayer MoS2 and MoSe2 crystals possess excellent optical qualities with very small full-width-half-maximum (FWHM) of 96 me V and 57 me V, respectively. It is comparable to that of exfoliated monolayers and reveals their high crystal quality. It is promising that our strategy should be applicable for the growth of other transition metal dichalcogenides (TMDs) monolayer crystals.

  9. Single crystal growth of pure and Nd-doped Y2O3 by flotating zone method with Xe arc lamp imaging furnace

    International Nuclear Information System (INIS)

    Tsuiki, H.; Kitazawa, K.; Fueki, K.; Masumoto, T.; Shiroki, K.

    1980-01-01

    Single crystals of undoped and Nd-doped yttrium oxide were grown by the floating zone method with a Xe arc lamp imaging furnace. The crystals were grown in the and directions. Transparent and subgrain-free single crystals were obtained at a growth rate of 30-60 mm/h for the undoped yttrium oxide. Facets of the cubic [100] and [211] were observed though the high temperature phase of the crystal is hexagonal. Dislocation densities of undoped yttrium oxide are given. (orig./WE)

  10. Crystal Growth Furnace (CGF)

    Science.gov (United States)

    Billingsley, Charles E.; Frederick, Larry

    1993-02-01

    The contract baseline, contract requirements review, contract modifications, contract problem areas and conclusions are addressed. Contract baseline was established 11 June 1987 and updated 1 December 1989. Significant changes were introduced into the 1989 baseline as compared to the original baseline. Contract modifications were made to add requirements as the program matured and as definition of requirements were completed. Problems were solved in real time through the contractor/customer team involvement and relationship to assure a timely and successful mission. The conclusion is that the CGF performed as designed and the experiments performed during the USML-1 Mission supports the conclusion.

  11. Single crystal fibers growth of double lithium, lanthanium molybdate and adjustment of a micro-pulling down furnace for high vacuum setup

    International Nuclear Information System (INIS)

    Silva, Fernando Rodrigues da

    2013-01-01

    In this work we investigated crystal growth procedures aiming the development of single crystal fiber (SCF) for laser applications. For quality optimization in the fabrication of fluorides SCF a new growth chamber for a micro-pulling down furnace (μ-PD) was constructed targeting the fibers fabrication with strict atmosphere control (high vacuum, gas flux and static atmospheres). Simultaneously, the SCF growth process of rare earth double molybdates was studied. The growth of pure and Nd 3+ -doped SCF of LiLa(MoO 4 ) 2 (LLM) was studied in the range of 0,5 - 10mol% doping. The designed furnace growth chamber with controlled atmosphere was successfully constructed and tested under different conditions. Specially, it was tested with the growth of LiF SFC under CF 4 atmosphere showing the expected results. Transparent and homogeneous SCF of Nd:LLM were grown. In the pure fibers was observed facets formation, however, these defects were minimized after tuning of the growth parameters and additionally with the fibers doping. X-ray analysis showed the crystallization of a single phase (space group I4 1 /a); the optical coherence tomography showed the presence of scattering centers only in regions were some growth stability occurred due to the manual process control. The measured Nd 3+ distribution showed uniform incorporation, indicative of a segregation coefficient close to unity in LLM. The potential laser gain of the system was determined using a numerical solution of the rate equations system for the 805nm, CW pumping regime, showing the maximum laser emission gain at 1.064 μm for a Nd 3+ -doping of 5mol%. (author)

  12. Experimental observation of the influence of furnace temperature profile on convection and segregation in the vertical Bridgman crystal growth technique

    Science.gov (United States)

    Neugebauer, G. T.; Wilcox, William R.

    1992-01-01

    Azulene-doped naphthalene was directionally solidified during the vertical Bridgman-Stockbarger technique. Doping homogeneity and convection were determined as a function of the temperature profile in the furnace and the freezing rate. Convection velocities were two orders of magnitude lower when the temperature increased with height. Rarely was the convection pattern axisymmetric, even though the temperature varied less than 0.1 K around the circumference of the growth ampoule. Correspondingly the cross sectional variation in azulene concentration tended to be asymmetric, especially when the temperature increased with height. This cross sectional variation changed dramatically along the ingot, reflecting changes in convection presumably due to the decreasing height of the melt. Although there was large scatter and irreproducibility in the cross sectional variation in doping, this variation tended to be least when the growth rate was low and the convection was vigorous. It is expected that compositional variations would also be small at high growth rates with weak convection and flat interfaces, although this was not investigated in the present experiments. Neither rotation of the ampoule nor deliberate introduction of thermal asymmetries during solidification had a significant influence on cross sectional variations in doping. It is predicted that slow directional solidification under microgravity conditions could produce greater inhomogeneities than on Earth. Combined use of microgravity and magnetic fields would be required to achieve homogeneity when it is necessary to freeze slowly in order to avoid constitutional supercooling.

  13. Study on the temperature field of large-sized sapphire single crystal furnace

    Science.gov (United States)

    Zhai, J. P.; Jiang, J. W.; Liu, K. G.; Peng, X. B.; Jian, D. L.; Li, I. L.

    2018-01-01

    In this paper, the temperature field of large-sized (120kg, 200kg and 300kg grade) sapphire single crystal furnace was simulated. By keeping the crucible diameter ratio and the insulation system unchanged, the power consumption, axial and radial temperature gradient, solid-liquid surface shape, stress distribution and melt flow were studied. The simulation results showed that with the increase of the single crystal furnace size, the power consumption increased, the temperature field insulation effect became worse, the growth stress value increased and the stress concentration phenomenon occurred. To solve these problems, the middle and bottom insulation system should be enhanced during designing the large-sized sapphire single crystal furnace. The appropriate radial and axial temperature gradient was favorable to reduce the crystal stress and prevent the occurrence of cracking. Expanding the interface between the seed and crystal was propitious to avoid the stress accumulation phenomenon.

  14. Purification and growth of LiF by induction heating furnace with electronic temperature control

    International Nuclear Information System (INIS)

    Faria Junior, R.N. de

    1985-01-01

    An eletronic power control system for a radio frequency generator and a quartz vacuum furnace heated by induction were developed. This furnace was employed for the growth of single crystals and purification of starting materials. A lithium fluoride single crystal was grown by the Czochralski technique in order to test the temperature control and the quartz furnace. An X-ray diffraction analysis of the crystal revealed the monocrystallinity high optical quality of the crystal obtained. Lithium fluoride of 95% purity prepared by Nuclemon starting material was purified by a vertical Bridgmann method. The emission spectrographic analysis of the purified crystal demonstrated the segregation of impurities. This study showed that the purification by this method of starting materials produced by local industry resulted in a crystal 99.9% pure in the first crystallization. (Author) [pt

  15. Growth of dopamine crystals

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Vidya, E-mail: vidya.patil@ruparel.edu; Patki, Mugdha, E-mail: mugdha.patki@ruparel.edu [D. G. Ruparel College, Senapati Bapat Marg, Mahim, Mumbai – 400 016 (India)

    2016-05-06

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  16. Crystal Growth of New Radiation Detector Materials in Microgravity, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — RMD proposes to conduct a series of crystal growth experiments on the International Space Station in the SUBSA furnace inside the MSG glovebox to grow crystals of...

  17. Crystal growth of various ruthenates

    Energy Technology Data Exchange (ETDEWEB)

    Kunkemoeller, Stefan; Braden, Markus [II. Physikalisches Institut, Universitaet zu Koeln (Germany); Nugroho, Agung [Institut Teknologi Bandung (Indonesia)

    2013-07-01

    Ruthenates of the Ruddlesdon-Popper series exhibit a variety of interesting phenomena ranging from unconventional superconductivity to orbitally polarized Mott insulators. Unfortunately the crystal growth of most of these ruthenates is extremely difficult partially due to the high evaporation of ruthenium; this strongly limits the research on these fascinating materials. We have started to grow single crystals of layered and perovskite ruthenates by the travelling floating-zone method using a Canon SC1-MDH mirror furnace. For the layered Ca{sub 2-x}Sr{sub x}RuO{sub 4} series we focused first on the range of concentration where recent My-SR experiments reveal spin-density wave ordering to occur at relatively high temperature and with a sizeable ordered moment. Good quality crystals of Ca{sub 1.5}Sr{sub 0.5}RuO{sub 4} can be obtained, when an excess of 15 percent of ruthenium is added to the initial preparation of the rod and when a high growth speed up to 40mm/h is used. Even slight modifications of the growing conditions result in large amounts of (Sr/Ca)RuO{sub 3} and (Sr/Ca){sub 3}Ru{sub 2}O{sub 7} intergrowth phases. First attempts to grow perovskite and double-layered ruthenates are discussed as well.

  18. Single crystal fibers growth of double lithium, lanthanium molybdate and adjustment of a micro-pulling down furnace for high vacuum setup; Crescimento de fibras de molibdato duplo de litio e lantanio e adaptacao de sistema de alto vacuo para micro pulling-down

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Fernando Rodrigues da

    2013-07-01

    In this work we investigated crystal growth procedures aiming the development of single crystal fiber (SCF) for laser applications. For quality optimization in the fabrication of fluorides SCF a new growth chamber for a micro-pulling down furnace ({mu}-PD) was constructed targeting the fibers fabrication with strict atmosphere control (high vacuum, gas flux and static atmospheres). Simultaneously, the SCF growth process of rare earth double molybdates was studied. The growth of pure and Nd{sup 3+}-doped SCF of LiLa(MoO{sub 4}){sub 2} (LLM) was studied in the range of 0,5 - 10mol% doping. The designed furnace growth chamber with controlled atmosphere was successfully constructed and tested under different conditions. Specially, it was tested with the growth of LiF SFC under CF{sub 4} atmosphere showing the expected results. Transparent and homogeneous SCF of Nd:LLM were grown. In the pure fibers was observed facets formation, however, these defects were minimized after tuning of the growth parameters and additionally with the fibers doping. X-ray analysis showed the crystallization of a single phase (space group I4{sub 1}/a); the optical coherence tomography showed the presence of scattering centers only in regions were some growth stability occurred due to the manual process control. The measured Nd{sup 3+} distribution showed uniform incorporation, indicative of a segregation coefficient close to unity in LLM. The potential laser gain of the system was determined using a numerical solution of the rate equations system for the 805nm, CW pumping regime, showing the maximum laser emission gain at 1.064 {mu}m for a Nd{sup 3+}-doping of 5mol%. (author)

  19. Crystal growth and crystallography

    Science.gov (United States)

    Chernov, A. A.

    1998-01-01

    Selected topics that may be of interest for both crystal-structure and crystal-growth communities are overviewed. The growth of protein crystals, along with that of some other compounds, is one of the topics, and recent insights into related phenomena are considered as examples of applications of general principles. The relationship between crystal growth shape and structure is reviewed and an attempt to introduce semiquantitative characterization of binding for proteins is made. The concept of kinks for complex structures is briefly discussed. Even at sufficiently low supersaturations, the fluctuation of steps may not be sufficient to implement the Gibbs-Thomson law if the kink density is low enough. Subsurface ordering of liquids and growth of rough interfaces from melts is discussed. Crystals growing in microgravity from solution should be more perfect if they preferentially trap stress-inducing impurities, thus creating an impurity-depleted zone around themselves. Evidently, such a zone is developed only around the crystals growing in the absence of convection. Under terrestrial conditions, the self-purified depleted zone is destroyed by convection, the crystal traps more impurity and grows stressed. The stress relief causes mosaicity. In systems containing stress-inducing but poorly trapped impurities, the crystals grown in the absence of convection should be worse than those of their terrestrial counterparts.

  20. A continuous Czochralski silicon crystal growth system

    Science.gov (United States)

    Wang, C.; Zhang, H.; Wang, T. H.; Ciszek, T. F.

    2003-03-01

    Demand for large silicon wafers has driven the growth of silicon crystals from 200 to 300 mm in diameter. With the increasing silicon ingot sizes, melt volume has grown dramatically. Melt flow becomes more turbulent as melt height and volume increase. To suppress turbulent flow in a large silicon melt, a new Czochralski (CZ) growth furnace has been designed that has a shallow melt. In this new design, a crucible consists of a shallow growth compartment in the center and a deep feeding compartment around the periphery. Two compartments are connected with a narrow annular channel. A long crystal may be continuously grown by feeding silicon pellets into the dedicated feeding compartment. We use our numerical model to simulate temperature distribution and velocity field in a conventional 200-mm CZ crystal growth system and also in the new shallow crucible CZ system. By comparison, advantages and disadvantages of the proposed system are observed, operating conditions are determined, and the new system is improved.

  1. Quartz crystal growth

    Science.gov (United States)

    Baughman, Richard J.

    1992-01-01

    A process for growing single crystals from an amorphous substance that can undergo phase transformation to the crystalline state in an appropriate solvent. The process is carried out in an autoclave having a lower dissolution zone and an upper crystallization zone between which a temperature differential (.DELTA.T) is maintained at all times. The apparatus loaded with the substance, solvent, and seed crystals is heated slowly maintaining a very low .DELTA.T between the warmer lower zone and cooler upper zone until the amorphous substance is transformed to the crystalline state in the lower zone. The heating rate is then increased to maintain a large .DELTA.T sufficient to increase material transport between the zones and rapid crystallization. .alpha.-Quartz single crystal can thus be made from fused quartz in caustic solvent by heating to 350.degree. C. stepwise with a .DELTA.T of 0.25.degree.-3.degree. C., increasing the .DELTA.T to about 50.degree. C. after the fused quartz has crystallized, and maintaining these conditions until crystal growth in the upper zone is completed.

  2. Springer Handbook of Crystal Growth

    CERN Document Server

    Dhanaraj, Govindhan; Prasad, Vishwanath; Dudley, Michael

    2010-01-01

    Over the years, many successful attempts have been made to describe the art and science of crystal growth. Most modern advances in semiconductor and optical devices would not have been possible without the development of many elemental, binary, ternary, and other compound crystals of varying properties and large sizes. The objective of the Springer Handbook of Crystal Growth is to present state-of-the-art knowledge of both bulk and thin-film crystal growth. The goal is to make readers understand the basics of the commonly employed growth processes, materials produced, and defects generated. Almost 100 leading scientists, researchers, and engineers from 22 different countries from academia and industry have been selected to write chapters on the topics of their expertise. They have written 52 chapters on the fundamentals of bulk crystal growth from the melt, solution, and vapor, epitaxial growth, modeling of growth processes and defects, techniques of defect characterization as well as some contemporary specia...

  3. Modeling and simulation of Si crystal growth from melt

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lijun; Liu, Xin; Li, Zaoyang [National Engineering Research Center for Fluid Machinery and Compressors, School of Energy and Power Engineering, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Miyazawa, Hiroaki; Nakano, Satoshi; Kakimoto, Koichi [Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan)

    2009-07-01

    A numerical simulator was developed with a global model of heat transfer for any crystal growth taking place at high temperature. Convective, conductive and radiative heat transfers in the furnace are solved together in a conjugated way by a finite volume method. A three-dimensional (3D) global model was especially developed for simulation of heat transfer in any crystal growth with 3D features. The model enables 3D global simulation be conducted with moderate requirement of computer resources. The application of this numerical simulator to a CZ growth and a directional solidification process for Si crystals, the two major production methods for crystalline Si for solar cells, was introduced. Some typical results were presented, showing the importance and effectiveness of numerical simulation in analyzing and improving these kinds of Si crystal growth processes from melt. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Effect of the Basicity on the Crystallization Behavior of Titanium Bearing Blast Furnace Slag

    Science.gov (United States)

    Meilong, Hu; Ruirui, Wei; Leizhang, Gao; Lu, Liu; Chenguang, Bai

    2018-03-01

    Basicity of titanium bearing blast furnace (BF) slag is critical for its crystallization behavior. Thermodynamics calculation indicates that rutile is the main phase after crystallization (or at room temperature). It precipitates during the cooling when the basicity of the slag is lower than 0.7. With increasing basicity, perovskite appears and becomes the main phase instead which contains titanium. Crystallization temperature of perovskite is higher than that of rutile and the other phases. Namely, perovskite crystallizes firstly from the molten slag during decreasing temperature. XRD analysis shows that CaTi21O38 is the main phase with a basicity of 0.6. CaMg0.39Al0.87Ti0.48Si1.26O6, CaTiSiO5 and CaMgSi2O6 are the main crystallization phases with a basicity of 0.8. The difference between experimental and thermodynamics calculation is due to the complicate crystallization behavior of the multiple slag under super cooling rate. When the slag basicity increases to 1.1, the main precipitatied phase is perovskite, which agrees well with theory calculation. In addition, the crystal structure of the synthesized titanium bearing slag is basically similar regardless of the basicity.

  5. Mathematical modeling and numerical simulation of Czochralski Crystal Growth

    Energy Technology Data Exchange (ETDEWEB)

    Jaervinen, J.; Nieminen, R. [Center for Scientific Computing, Espoo (Finland)

    1996-12-31

    A detailed mathematical model and numerical simulation tools based on the SUPG Finite Element Method for the Czochralski crystal growth has been developed. In this presentation the mathematical modeling and numerical simulation of the melt flow and the temperature distribution in a rotationally symmetric crystal growth environment is investigated. The temperature distribution and the position of the free boundary between the solid and liquid phases are solved by using the Enthalpy method. Heat inside of the Czochralski furnace is transferred by radiation, conduction and convection. The melt flow is governed by the incompressible Navier-Stokes equations coupled with the enthalpy equation. The melt flow is numerically demonstrated and the temperature distribution in the whole Czochralski furnace. (author)

  6. Protein crystal growth - Growth kinetics for tetragonal lysozyme crystals

    Science.gov (United States)

    Pusey, M. L.; Snyder, R. S.; Naumann, R.

    1986-01-01

    Results are reported from theoretical and experimental studies of the growth rate of lysozyme as a function of diffusion in earth-gravity conditions. The investigations were carried out to form a comparison database for future studies of protein crystal growth in the microgravity environment of space. A diffusion-convection model is presented for predicting crystal growth rates in the presence of solutal concentration gradients. Techniques used to grow and monitor the growth of hen egg white lysozyme are detailed. The model calculations and experiment data are employed to discuss the effects of transport and interfacial kinetics in the growth of the crystals, which gradually diminished the free energy in the growth solution. Density gradient-driven convection, caused by presence of the gravity field, was a limiting factor in the growth rate.

  7. Growth of ruby crystals by the heat exchanger method, phase 1: NSF small business innovation research

    Science.gov (United States)

    Schmid, F.; Khattak, C. P.

    1980-03-01

    Conditions for the growth of large, uniformly doped laser crystals by the heat exchanger method are explored. Determination of the melt point, selection of crucible material and establishment of furnace operating parameters are discussed. The melt point of ruby was found to be 2040 plus or minus 10 C. Molybdenum crucibles can be used to contain ruby in vacuum as well as under argon atmospheres at desired superheat temperatures over extended periods required for crystal growth. Thermodynamic analysis was conducted and vapor pressures of volatile species calculated. Experimentally, volatilization of chromium oxides was suppressed by using welded covers on crucibles and operating under an argon pressure in the furnace.

  8. Mutiple Czochralski growth of silicon crystals from a single crucible

    Science.gov (United States)

    Lane, R. L.; Kachare, A. H.

    1980-01-01

    An apparatus for the Czochralski growth of silicon crystals is presented which is capable of producing multiple ingots from a single crucible. The growth chamber features a refillable crucible with a water-cooled, vacuum-tight isolation valve located between the pull chamber and the growth furnace tank which allows the melt crucible to always be at vacuum or low argon pressure when retrieving crystal or introducing recharge polysilicon feed stock. The grower can thus be recharged to obtain 100 kg of silicon crystal ingots from one crucible, and may accommodate crucibles up to 35 cm in diameter. Evaluation of the impurity contents and I-V characteristics of solar cells fabricated from seven ingots grown from two crucibles reveals a small but consistent decrease in cell efficiency from 10.4% to 9.6% from the first to the fourth ingot made in a single run, which is explained by impurity build-up in the residual melt. The crystal grower thus may offer economic benefits through the extension of crucible lifetime and the reduction of furnace downtime.

  9. Growth of emerald single crystals

    International Nuclear Information System (INIS)

    Bukin, G.V.; Godovikov, A.A.; Klyakin, V.A.; Sobolev, V.S.

    1986-01-01

    In addition to its use for jewelry, emerald can also be used in low-noise microwave amplifiers. The authors discuss flux crystallization of emerald and note that when emerald is grown by this method, it is desirable to use solvents which dissolve emerald with minimum deviations from congruence but at the same time with sufficient high efficiency. Emerald synthesis and crystal growth from slowly cooled solutions is discussed as another possibility. The techniques are examined. Vapor synthesis and growht of beryl crystals re reviewed and the authors experimentally study the seeded CVD crystallization of beryl from BeO, Al 2 O 3 and SiO 2 oxides, by using complex compounds as carrier agents. The color of crystals of emerald and other varieties of beryl is detemined by slelective light absorption in teh visible part of the spectrum and depends on the density and structural positions of chromphore ions: chromium, iron, vanadium, nickel, manganese and cobalt

  10. Hydrothermal Growth of Polyscale Crystals

    Science.gov (United States)

    Byrappa, Kullaiah

    In this chapter, the importance of the hydrothermal technique for growth of polyscale crystals is discussed with reference to its efficiency in synthesizing high-quality crystals of various sizes for modern technological applications. The historical development of the hydrothermal technique is briefly discussed, to show its evolution over time. Also some of the important types of apparatus used in routine hydrothermal research, including the continuous production of nanosize crystals, are discussed. The latest trends in the hydrothermal growth of crystals, such as thermodynamic modeling and understanding of the solution chemistry, are elucidated with appropriate examples. The growth of some selected bulk, fine, and nanosized crystals of current technological significance, such as quartz, aluminum and gallium berlinites, calcite, gemstones, rare-earth vanadates, electroceramic titanates, and carbon polymorphs, is discussed in detail. Future trends in the hydrothermal technique, required to meet the challenges of fast-growing demand for materials in various technological fields, are described. At the end of this chapter, an Appendix 18.A containing a more or less complete list of the characteristic families of crystals synthesized by the hydrothermal technique is given with the solvent and pressure-temperature (PT) conditions used in their synthesis.

  11. Nucleation and crystal growth in batch crystallizers

    NARCIS (Netherlands)

    Janse, A.H.

    1977-01-01

    The aim of the present work is to gain knowledge of the mechanism of formation of the crystal size distribution in batch crystallizers in order to give directives for design and operation of batch crystallizers. The crystal size distribution is important for the separation of crystals and mother

  12. Growth morphologies of crystal surfaces

    Science.gov (United States)

    Xiao, Rong-Fu; Alexander, J. Iwan D.; Rosenberger, Franz

    1991-03-01

    We have expanded our earlier Monte Carlo model [Phys. Rev. A 38, 2447 (1988); J. Crystal Growth 100, 313 (1990)] to three dimensions and included reevaporation after accommodation and growth on dislocation-induced steps. We found again that, for a given set of growth parameters, the critical size, beyond which a crystal cannot retain its macroscopically faceted shape, scales linearly with the mean free path in the vapor. However, the three-dimensional (3D) the systems show increased shape stability compared to corresponding 2D cases. Extrapolation of the model results to mean-free-path conditions used in morphological stability experiments leads to order-of-magnitude agreement of the predicted critical size with experimental findings. The stability region for macroscopically smooth (faceted) surfaces in the parameter space of temperature and supersaturation depends on both the surface and bulk diffusion. While surface diffusion is seen to smooth the growth morphology on the scale of the surface diffusion length, bulk diffusion is always destabilizing. The atomic surface roughness increases with increase in growth temperature and supersaturation. That is, the tendency of surface kinetics anisotropies to stabilize the growth shape is reduced through thermal and kinetic roughening. It is also found that the solid-on-solid assumption, which can be advantageously used at low temperatures and supersaturations, is insufficient to describe the growth dynamics of atomically rough interfaces where bulk diffusion governs the process. For surfaces with an emerging screw dislocation, we find that the spiral growth mechanism dominates at low temperatures and supersaturations. The polygonization of a growth spiral decreases with increasing temperature or supersaturation. When the mean free path in the nutrient is comparable to the lattice constant, the combined effect of bulk and surface diffusion reduces the terrace width of a growth spiral in its center region. At elevated

  13. Phase diagrams and crystal growth

    Science.gov (United States)

    Venkrbec, Jan

    1980-04-01

    Phase diagrams are briefly treated as generalized property-composition relationships, with respect to crystal technology optimization. The treatment is based on mutual interaction of three systems related to semiconductors: (a) the semiconducting material systems, (b0 the data bank, (c) the system of crystallization methods. A model is proposed enabling optimatization on the path from application requirements to the desired material. Further, several examples of the selection as to the composition of LED and laser diode material are given. Some of molten-solution-zone methods are being successfully introduced for this purpose. Common features of these methods, the application of phase diagrams, and their pecularities compared with other crystallization methods are illustrated by schematic diagrams and by examples. LPE methods, particularly the steady-state LPE methods such as Woodall's ISM and Nishizawa's TDM-CVP, and the CAM-S (Crystallization Method Providing Composition Autocontrol in Situ) have been chosen as examples. Another approach of exploiting phase diagrams for optimal material selection and for determination of growth condition before experimentation through a simple calculation is presented on InP-GaP solid solutions. Ternary phase diagrams are visualized in space through calculation and constructions based on the corresponding thermodynamic models and anaglyphs. These make it easy to observe and qualitatively analyze the crystallization of every composition. Phase diagrams can be also used as a powerful tool for the deduction of new crystallization methods. Eutectic crystallization is an example of such an approach where a modified molten-solution-zone method can give a sandwich structure with an abrupt concentration change. The concentration of a component can range from 0 to 100% in the different solid phases.

  14. Deposit growth and property development in coal-fired furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, L. [Sandia National Lab., Livermore, CA (United States)

    1995-11-01

    The objectives of this research project are: (1) to provide a self-consistent database of simultaneously measured, time-resolved ash deposit properties in well-controlled and well-defined environments and (2) to provide analytical expressions that relate deposit composition and structure to deposit properties of immediate relevance to PETC`s Combustion 2000 program. This project is distinguished from related work being done elsewhere by: (1) the development and deployment of in-situ diagnostics to monitor deposit properties, including heat transfer coefficients, porosity, emissivity, tenacity, strength, density, and viscosity; (2) the time resolution of such properties during deposit growth; (3) simultaneous measurement of structural and composition properties; (4) development of algorithms from a self-consistent, simultaneously measured database that includes the interdependence of properties; and (5) application of the results to technologically relevant environments such as those being planned under Combustion 2000 program. Work completed during FY94 emphasized diagnostic development. During FY95, this development work will be completed and we will emphasize application of the diagnostics to meet the other project objectives. Included in this work are the development and application of two in-situ, real-time diagnostic systems for monitoring the properties of inorganic materials on Heat transfer surfaces and in the gas-phase during controlled combustion of selected coal samples in Sandia`s Multifuel Combustor (MFC). Also, several diagnostics are being incorporated into the MFC that will eventually be used to characterize ash deposit properties.

  15. Growth of Nd 3 doped LiNbO3 crystals using Bridgman method and ...

    Indian Academy of Sciences (India)

    ... sealed platinum crucibles, growth rate of 1–1.5 mm/h and temperature gradient of 30–35°C/cm across the solid–liquid interface under the furnace temperature of 1300°C, single crystals containing Nd3+ ion with 0.54 mol% concentration were obtained. X-ray diffraction and ICP–AES were used to characterize the crystals ...

  16. Czochralski growth of gallium indium antimonide alloy crystals

    Energy Technology Data Exchange (ETDEWEB)

    Tsaur, S.C.

    1998-02-01

    Attempts were made to grow alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb by the conventional Czochralski process. A transparent furnace was used, with hydrogen purging through the chamber during crystal growth. Single crystal seeds up to about 2 to 5 mole% InSb were grown from seeds of 1 to 2 mole% InSb, which were grown from essentially pure GaSb seeds of the [111] direction. Single crystals were grown with InSb rising from about 2 to 6 mole% at the seed ends to about 14 to 23 mole% InSb at the finish ends. A floating-crucible technique that had been effective in reducing segregation in doped crystals, was used to reduce segregation in Czochralski growth of alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb. Crystals close to the targeted composition of 1 mole% InSb were grown. However, difficulties were encountered in reaching higher targeted InSb concentrations. Crystals about 2 mole% were grown when 4 mole% was targeted. It was observed that mixing occurred between the melts rendering the compositions of the melts; and, hence, the resultant crystal unpredictable. The higher density of the growth melt than that of the replenishing melt could have triggered thermosolutal convection to cause such mixing. It was also observed that the floating crucible stuck to the outer crucible when the liquidus temperature of the replenishing melt was significantly higher than that of the growth melt. The homogeneous Ga{sub 1{minus}x}In{sub x}Sb single crystals were grown successfully by a pressure-differential technique. By separating a quartz tube into an upper chamber for crystal growth and a lower chamber for replenishing. The melts were connected by a capillary tube to suppress mixing between them. A constant pressure differential was maintained between the chambers to keep the growth melt up in the growth chamber. The method was first tested with a low temperature alloy Bi{sub 1{minus}x}Sb{sub x}. Single crystals of Ga{sub 1{minus}x}In{sub x}Sb were grown with uniform

  17. Introduction to crystal growth and characterization

    CERN Document Server

    Benz, Klaus-Werner

    2014-01-01

    This new textbook provides for the first time a comprehensive treatment of the basics of contemporary crystallography and crystal growth in a single volume. The reader will be familiarized with the concepts for the description of morphological and structural symmetry of crystals. The architecture of crystal structures of selected inorganic and molecular crystals is illustrated. The main crystallographic databases as data sources of crystal structures are described. Nucleation processes, their kinetics and main growth mechanism will be introduced in fundamentals of crystal growth. Some phase d

  18. Hanging drop crystal growth apparatus

    Science.gov (United States)

    Naumann, Robert J. (Inventor); Witherow, William K. (Inventor); Carter, Daniel C. (Inventor); Bugg, Charles E. (Inventor); Suddath, Fred L. (Inventor)

    1990-01-01

    This invention relates generally to control systems for controlling crystal growth, and more particularly to such a system which uses a beam of light refracted by the fluid in which crystals are growing to detect concentration of solutes in the liquid. In a hanging drop apparatus, a laser beam is directed onto drop which refracts the laser light into primary and secondary bows, respectively, which in turn fall upon linear diode detector arrays. As concentration of solutes in drop increases due to solvent removal, these bows move farther apart on the arrays, with the relative separation being detected by arrays and used by a computer to adjust solvent vapor transport from the drop. A forward scattering detector is used to detect crystal nucleation in drop, and a humidity detector is used, in one embodiment, to detect relative humidity in the enclosure wherein drop is suspended. The novelty of this invention lies in utilizing angular variance of light refracted from drop to infer, by a computer algorithm, concentration of solutes therein. Additional novelty is believed to lie in using a forward scattering detector to detect nucleating crystallites in drop.

  19. Controlled growth of semiconductor crystals

    Science.gov (United States)

    Bourret-Courchesne, Edith D.

    1992-01-01

    A method for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B.sub.x O.sub.y are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T.sub.m1 of the oxide of boron (T.sub.m1 =723.degree. K. for boron oxide B.sub.2 O.sub.3), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T.sub.m2 of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm.sup.2. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 .mu.m.

  20. Principles of crystallization, and methods of single crystal growth

    International Nuclear Information System (INIS)

    Chacra, T.

    2010-01-01

    Most of single crystals (monocrystals), have distinguished optical, electrical, or magnetic properties, which make from single crystals, key elements in most of technical modern devices, as they may be used as lenses, Prisms, or grating sin optical devises, or Filters in X-Ray and spectrographic devices, or conductors and semiconductors in electronic, and computer industries. Furthermore, Single crystals are used in transducer devices. Moreover, they are indispensable elements in Laser and Maser emission technology.Crystal Growth Technology (CGT), has started, and developed in the international Universities and scientific institutions, aiming at some of single crystals, which may have significant properties and industrial applications, that can attract the attention of international crystal growth centers, to adopt the industrial production and marketing of such crystals. Unfortunately, Arab universities generally, and Syrian universities specifically, do not give even the minimum interest, to this field of Science.The purpose of this work is to attract the attention of Crystallographers, Physicists and Chemists in the Arab universities and research centers to the importance of crystal growth, and to work on, in the first stage to establish simple, uncomplicated laboratories for the growth of single crystal. Such laboratories can be supplied with equipment, which are partly available or can be manufactured in the local market. Many references (Articles, Papers, Diagrams, etc..) has been studied, to conclude the most important theoretical principles of Phase transitions,especially of crystallization. The conclusions of this study, are summarized in three Principles; Thermodynamic-, Morphologic-, and Kinetic-Principles. The study is completed by a brief description of the main single crystal growth methods with sketches, of equipment used in each method, which can be considered as primary designs for the equipment, of a new crystal growth laboratory. (author)

  1. Economic analysis of crystal growth in space

    Science.gov (United States)

    Ulrich, D. R.; Chung, A. M.; Yan, C. S.; Mccreight, L. R.

    1972-01-01

    Many advanced electronic technologies and devices for the 1980's are based on sophisticated compound single crystals, i.e. ceramic oxides and compound semiconductors. Space processing of these electronic crystals with maximum perfection, purity, and size is suggested. No ecomonic or technical justification was found for the growth of silicon single crystals for solid state electronic devices in space.

  2. Dendritic growth forms of borax crystals

    International Nuclear Information System (INIS)

    Takoo, R.K.; Patel, B.R.; Joshi, M.S.

    1983-01-01

    A variety of dendritic forms of borax grown from solutions by the film formation method is given. The changing growth morphology is followed as a function of concentration and temperature. The initial, intermediate and final growth morphologies are described and discussed. Influence of evaporation rate and supersaturation on the mechanism of growth is assessed. It is suggested that under all crystallization conditions, borax crystals have dendritic form in the initial stages of growth. (author)

  3. Homogeneous SiGe crystal growth in microgravity by the travelling liquidus-zone method

    International Nuclear Information System (INIS)

    Kinoshita, K; Arai, Y; Inatomi, Y; Sakata, K; Takayanagi, M; Yoda, S; Miyata, H; Tanaka, R; Sone, T; Yoshikawa, J; Kihara, T; Shibayama, H; Kubota, Y; Shimaoka, T; Warashina, Y

    2011-01-01

    Homogeneous SiGe crystal growth experiments will be performed on board the ISS 'Kibo' using a gradient heating furnace (GHF). A new crystal growth method invented for growing homogeneous mixed crystals named 'travelling liquidus-zone (TLZ) method' is evaluated by the growth of Si 0.5 Ge 0.5 crystals in space. We have already succeeded in growing homogeneous 2mm diameter Si 0.5 Ge 0.5 crystals on the ground but large diameter homogeneous crystals are difficult to be grown due to convection in a melt. In microgravity, larger diameter crystals can be grown with suppressing convection. Radial concentration profiles as well as axial profiles in microgravity grown crystals will be measured and will be compared with our two-dimensional TLZ growth model equation and compositional variation is analyzed. Results are beneficial for growing large diameter mixed crystals by the TLZ method on the ground. Here, we report on the principle of the TLZ method for homogeneous crystal growth, results of preparatory experiments on the ground and plan for microgravity experiments.

  4. Phase-field crystal simulation facet and branch crystal growth

    Science.gov (United States)

    Chen, Zhi; Wang, Zhaoyang; Gu, Xinrui; Chen, Yufei; Hao, Limei; de Wit, Jos; Jin, Kexin

    2018-05-01

    Phase-field crystal model with one mode is introduced to describe morphological transition. The relationship between growth morphology and smooth density distribution was investigated. The results indicate that the pattern selection of dendrite growth is caused by the competition between interface energy anisotropy and interface kinetic anisotropy based on the 2D phase diagram. When the calculation time increases, the crystal grows to secondary dendrite at the dimensionless undercooling equal to - 0.4. Moreover, when noise is introduced in the growth progress, the symmetry is broken in the growth mode, and there becomes irregular fractal-like growth morphology. Furthermore, the single crystal shape develops into polycrystalline when the noise amplitude is large enough. When the dimensionless undercooling is less than - 0.3, the noise has a significant effect on the growth shape. In addition, the growth velocity of crystal near to liquid phase line is slow, while the shape far away from the liquid adapts to fast growth. Based on the simulation results, the method was proved to be effective, and it can easily obtain different crystal shapes by choosing the different points in 2D phase diagram.

  5. Microscopic kinetic model for polymer crystal growth

    Science.gov (United States)

    Hu, Wenbing

    2011-03-01

    Linear crystal growth rates characterize the net result of competition between growth and melting at the liquid-solid interfaces. The rate equation for polymer crystal growth can be derived with a barrier term for crystal growth and with a driving force term of excess lamellar thickness, provided that growth and melting share the same rate-determining steps at the growth front. Such an ansatz can be verified by the kinetic symmetry between growth and melting around the melting point of lamellar crystals, as made in our recent dynamic Monte Carlo simulations. The profile of the growth/melting front appears as wedge-shaped, with the free energy barrier for intramolecular secondary crystal nucleation at its top, and with the driving force gained via instant thickening at its bottom. Such a scenario explains unique phenomena on polymer crystal growth, such as chain folding, regime transitions, molecular segregation of polydisperse polymers, self-poisoning with integer-number chain-folding of short chains, and colligative growth rates of binary mixtures of two chain lengths. Financial support from NNSFC No. 20825415 and NBRPC No. 2011CB606100 is acknowledged.

  6. Growth of single crystals of BaFe12O19 by solid state crystal growth

    Science.gov (United States)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-10-01

    Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

  7. Materials discovery through crystal growth

    Science.gov (United States)

    zur Loye, Hans-Conrad

    2016-04-01

    The discovery of new materials and associated desirable properties has been a driving force behind chemical innovation for centuries. When we look at some of the many recent technological advances, and how widespread and significant their impact has been, we appreciate how much they have relied on new materials. The increase in hard drive storage capacity due to new giant magneto-resistive materials, the ever-shrinking cell phone due to improved microwave dielectric materials, the enhancement in lithium battery storage capacity due to new intercalation materials, or the improved capacitor due to new ferroelectric materials are all excellent examples. How were these materials discovered? While there is no single answer, in all cases there was a First-Material, the archetype in which the phenomenon was first observed, the one that led to further investigations and the subsequent preparation of improved 2nd or 3rd generation materials. It is this First-Material, the archetype, that was discovered - often via crystal growth.

  8. Growth of single crystals of BaFe12O19 by solid state crystal growth

    International Nuclear Information System (INIS)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-01-01

    Single crystals of BaFe 12 O 19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe 12 O 19 are buried in BaFe 12 O 19 +1 wt% BaCO 3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe 12 O 19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe 12 O 19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth. - Highlights: • Single crystals of BaFe 12 O 19 are grown by solid state crystal growth. • A single crystal up to ∼130 μm thick (c-axis direction) grows on the seed crystal. • The single crystal and surrounding ceramic matrix have similar composition. • Micro-Raman scattering shows the single crystal has the BaFe 12 O 19 structure.

  9. Development of a new micro-furnace for "in situ" high-temperature single crystal X-ray diffraction measurements

    Science.gov (United States)

    Alvaro, Matteo; Angel, Ross J.; Marciano, Claudio; Zaffiro, Gabriele; Scandolo, Lorenzo; Mazzucchelli, Mattia L.; Milani, Sula; Rustioni, Greta; Domeneghetti, Chiara M.; Nestola, Fabrizio

    2015-04-01

    Several experimental methods to reliably determine elastic properties of minerals at non-ambient conditions have been developed. In particular, different techniques for generating high-pressure and high-temperature have been successfully adopted for single-crystal and powder X-ray diffraction measurements. High temperature devices for "in-situ" measurements should provide the most controlled isothermal environment as possible across the entire sample. It is intuitive that in general, thermal gradients across the sample increase as the temperature increases. Even if the small isothermal volume required for single-crystal X-ray diffraction experiments makes such phenomena almost negligible, the design of a furnace should also aim to reduce thermal gradients by including a large thermal mass that encloses the sample. However this solution often leads to complex design that results in a restricted access to reciprocal space or attenuation of the incident or diffracted intensity (with consequent reduction of the accuracy and/or precision in lattice parameter determination). Here we present a newly-developed H-shaped Pt-Pt/Rh resistance microfurnace for in-situ high-temperature single-crystal X-ray diffraction measurements. The compact design of the furnace together with the long collimator-sample-detector distance allows us to perform measurements up to 2θ = 70° with no further restrictions on any other angular movement. The microfurnace is equipped with a water cooling system that allows a constant thermal gradient to be maintained that in turn guarantees thermal stability with oscillations smaller than 5°C in the whole range of operating T of room-T to 1200°C. The furnace has been built for use with a conventional 4-circle Eulerian geometry equipped with point detector and automated with the SINGLE software (Angel and Finger 2011) that allows the effects of crystal offsets and diffractometer aberrations to be eliminated from the refined peak positions by the 8

  10. A high compression crystal growth system

    International Nuclear Information System (INIS)

    Nieman, H.F.; Walton, A.A.; Powell, B.M.; Dolling, G.

    1980-01-01

    This report describes the construction and operating procedure for a high compression crystal growth system, capable of growing single crystals from the fluid phase over the temperature range of 4.2 K to 300 K, at pressures up to 900 MPa. Some experimental results obtained with the system are given for solid β-nitrogen. (auth)

  11. Technology of gallium nitride crystal growth

    CERN Document Server

    Ehrentraut, Dirk; Bockowski, Michal

    2010-01-01

    This book deals with the important technological aspects of the growth of GaN single crystals by HVPE, MOCVD, ammonothermal and flux methods for the purpose of free-standing GaN wafer production. Leading experts from industry and academia report in a very comprehensive way on the current state-of-the-art of the growth technologies and optical and structural properties of the GaN crystals are compared.

  12. Crystal growth of uranium compounds and study of UGe2

    International Nuclear Information System (INIS)

    Taufour, V.

    2011-01-01

    In this thesis, the study on the superconducting ferromagnet UGe 2 is presented. Crystal growth of UGe 2 single crystals was realized in a tetra-arc furnace using the Czochralski technique. This technique was also used to obtain high quality single crystals of other uranium compounds, notably UCoGe and URu 2 Si 2 . The Curie temperature of UGe 2 (T(Curie) = 53 K) decreases with pressure and is suppressed at p c = 1.5 GPa. Before being suppressed, the ferromagnetic transition changes from second to first order at a tricritical point. Precise resistivity and Hall resistivity measurements under pressure and magnetic field revealed the position of the tricritical point as well as its evolution under magnetic field which draw a wing structure phase diagram. Despite the theoretical prediction that this diagram is general for a ferromagnet, here we present the first experimental observation. Other measurements focus on the superconductivity (T sc = 0.75 K) which coexists with ferromagnetism under pressure. The bulk nature of the superconductivity is investigated by AC calorimetry measurements under pressure. The attention is turned to the interesting phenomenon of field enhanced superconductivity. (author) [fr

  13. Protein crystal growth in low gravity

    Science.gov (United States)

    Feigelson, Robert S.

    1993-01-01

    This Final Technical Report for NASA Grant NAG8-774 covers the period from April 27, 1989 through December 31, 1992. It covers five main topics: fluid flow studies, the influence of growth conditions on the morphology of isocitrate lyase crystals, control of nucleation, the growth of lysozyme by the temperature gradient method and graphoepitaxy of protein crystals. The section on fluid flow discusses the limits of detectability in the Schlieren imaging of fluid flows around protein crystals. The isocitrate lyase study compares crystals grown terrestrially under a variety of conditions with those grown in space. The controlling factor governing the morphology of the crystals is the supersaturation. The lack of flow in the interface between the drop and the atmosphere in microgravity causes protein precipitation in the boundary layer and a lowering of the supersaturation in the drop. This lowered supersaturation leads to improved crystal morphology. Preliminary experiments with lysozyme indicated that localized temperature gradients could be used to nucleate crystals in a controlled manner. An apparatus (thermonucleator) was designed to study the controlled nucleation of protein crystals. This apparatus has been used to nucleate crystals of materials with both normal (ice-water, Rochelle salt and lysozyme) and retrograde (horse serum albumin and alpha chymotrypsinogen A) solubility. These studies have lead to the design of an new apparatus that small and more compatible with use in microgravity. Lysozyme crystals were grown by transporting nutrient from a source (lysozyme powder) to the crystal in a temperature gradient. The influence of path length and cross section on the growth rate was demonstrated. This technique can be combined with the thermonucleator to control both nucleation and growth. Graphoepitaxy utilizes a patterned substrate to orient growing crystals. In this study, silicon substrates with 10 micron grooves were used to grow crystals of catalase

  14. Ultraslow growth rates of giant gypsum crystals

    Science.gov (United States)

    Van Driessche, A. E. S.; García-Ruíz, J. M.; Tsukamoto, K.; Patiño-Lopez, L. D.; Satoh, H.

    2011-01-01

    Mineralogical processes taking place close to equilibrium, or with very slow kinetics, are difficult to quantify precisely. The determination of ultraslow dissolution/precipitation rates would reveal characteristic timing associated with these processes that are important at geological scale. We have designed an advanced high-resolution white-beam phase-shift interferometry microscope to measure growth rates of crystals at very low supersaturation values. To test this technique, we have selected the giant gypsum crystals of Naica ore mines in Chihuahua, Mexico, a challenging subject in mineral formation. They are thought to form by a self-feeding mechanism driven by solution-mediated anhydrite-gypsum phase transition, and therefore they must be the result of an extremely slow crystallization process close to equilibrium. To calculate the formation time of these crystals we have measured the growth rates of the {010} face of gypsum growing from current Naica waters at different temperatures. The slowest measurable growth rate was found at 55 °C, 1.4 ± 0.2 × 10-5 nm/s, the slowest directly measured normal growth rate for any crystal growth process. At higher temperatures, growth rates increase exponentially because of decreasing gypsum solubility and higher kinetic coefficient. At 50 °C neither growth nor dissolution was observed indicating that growth of giant crystals of gypsum occurred at Naica between 58 °C (gypsum/anhydrite transition temperature) and the current temperature of Naica waters, confirming formation temperatures determined from fluid inclusion studies. Our results demonstrate the usefulness of applying advanced optical techniques in laboratory experiments to gain a better understanding of crystal growth processes occurring at a geological timescale. PMID:21911400

  15. Non-linear optical titanyl arsenates: Crystal growth and properties

    Science.gov (United States)

    Nordborg, Jenni Eva Louise

    Crystals are appreciated not only for their appearance, but also for their unique physical properties which are utilized by the photonic industry in appliances that we come across every day. An important part of enabling the technical use of optical devices is the manufacture of crystals. This dissertation deals with a specific group of materials called the potassium titanyl phosphate (KIP) family, known for their non-linear optical and ferroelectric properties. The isomorphs vary in their linear optical and dielectric properties, which can be tuned to optimize device performance by forming solid solutions of the different materials. Titanyl arsenates have a wide range of near-infrared transmission which makes them useful for tunable infrared lasers. The isomorphs examined in the present work were primarily RbTiOASO4 (RTA) and CsTiOAsO4 (CTA) together with the mixtures RbxCs 1-xTiOAsO4 (RCTA). Large-scale crystals were grown by top seeding solution growth utilizing a three-zone furnace with excellent temperature control. Sufficiently slow cooling and constant upward lifting produced crystals with large volumes useable for technical applications. Optical quality RTA crystals up to 10 x 12 x 20 mm were grown. The greater difficulty in obtaining good crystals of CTA led to the use of mixed RCTA materials. The mixing of rubidium and cesium in RCTA is more favorable to crystal growth than the single components in pure RTA and CTA. Mixed crystals are rubidium-enriched and contain only 20-30% of the cesium concentration in the flux. The cesium atoms show a preference for the larger cation site. The network structure is very little affected by the cation substitution; consequently, the non-linear optical properties of the Rb-rich isomorphic mixtures of RTA and CTA can be expected to remain intact. Crystallographic methods utilizing conventional X-ray tubes, synchrotron radiation and neutron diffraction have been employed to investigate the properties of the atomic

  16. Crystal growth of bismuth tungstate

    Energy Technology Data Exchange (ETDEWEB)

    De L' Eprevier, A. G.; Shukla, V. N.; Payne, D. A.

    1979-01-01

    Bi/sub 2/WO/sub 6/ is a polar material in the bismuth titanate family, Bi/sub 2/M/sub n-1/R/sub n/0/sub 3n+3/. Additions of NaF to a Na/sub 2/WO/sub 4/ - WO/sub 3/ flux yielded large single crystals up to 0.8 mm thick, which were free of inclusions. Total impurities were less than 500 ppM, and the crystals were single domain.

  17. Ultra-high vacuum compatible image furnace.

    Science.gov (United States)

    Neubauer, A; Boeuf, J; Bauer, A; Russ, B; Löhneysen, H v; Pfleiderer, C

    2011-01-01

    We report the design of an optical floating-zone furnace for single-crystal growth under ultra-high vacuum (UHV) compatible conditions. The system is based on a commercial image furnace, which has been refurbished to be all-metal sealed. Major changes concern the use of UHV rotary feedthroughs and bespoke quartz-metal seals with metal-O-rings at the lamp stage. As a consequence, the procedure of assembling the furnace for crystal growth is changed completely. Bespoke heating jackets permit to bake the system. For compounds with elevated vapor pressures, the ultra-high vacuum serves as a precondition for the use of a high-purity argon atmosphere up to 10 bar. In the ferromagnetic Heusler compound Cu(2)MnAl, the improvements of purity result in an improved stability of the molten zone, grain selection, and, hence, single-crystal growth. Similar improvements are observed in traveling-solvent floating-zone growth of the antiferromagnetic Heusler compound Mn(3)Si. These improvements underscore the great potential of optical float-zoning for the growth of high-purity single crystals of intermetallic compounds.

  18. Crystal growth and computational materials science

    International Nuclear Information System (INIS)

    Jayakumar, S.; Ravindran, P.; Arun Kumar, R.; Sudarshan, C.

    2012-01-01

    The proceedings of the international conference on advanced materials discusses the advances being made in the area of single crystals, their preparation and device development from these crystals and details of the progress that is taking place in the computational field relating to materials science. Computational materials science makes use of advanced simulation tools and computer interfaces to develop a virtual platform which can provide a model for real-time experiments. This book includes selected papers in topics of crystal growth and computational materials science. We are confident that the new concepts and results presented will stimulate and enhance progress of research on crystal growth and computational materials science. Papers relevant to INIS are indexed separately

  19. Numerical investigations on hot-zone modified DS furnace for mc-Si growth process

    Energy Technology Data Exchange (ETDEWEB)

    Sanmugavel, S.; Srinivasan, M.; Aravinth, K.; Ramasamy, P., E-mail: ramasamyp@ssn.edu.in [SSN Research Centre, SSN College of Engineering, Chennai - 603 110 (India)

    2016-05-23

    A transient global numerical model has been carried out to simulate the multi-crystalline silicon growth process by the directional solidification method using CGSim 15.1. A two dimensional axisymmetric model was used. The conductive, convective, and radiative heat transfer problems were coupled with our model and these problems were solved iteratively using the finite volume method. In the present work we have modified the heater element to produce a high quality ingot from multi-crystalline silicon. The change has been made to control the temperature distribution. By controlling the temperature distribution, we can also control the melt crystal interface of the ingot. The shape of the melt-crystal interface of the ingot, the temperature distribution in the crucible and the heat flux from the melt as well as from the crystal have been studied. Finally, the simulation results show that the modification in the heater element keeps the melt-crystal interface as planar in the DS system, also it gives better results than conventional system.

  20. Biomolecular Modification of Inorganic Crystal Growth

    Energy Technology Data Exchange (ETDEWEB)

    De Yoreo, J J

    2007-04-27

    The fascinating shapes and hierarchical designs of biomineralized structures are an inspiration to materials scientists because of the potential they suggest for biomolecular control over materials synthesis. Conversely, the failure to prevent or limit tissue mineralization in the vascular, skeletal, and urinary systems is a common source of disease. Understanding the mechanisms by which organisms direct or limit crystallization has long been a central challenge to the biomineralization community. One prevailing view is that mineral-associated macromolecules are responsible for either inhibiting crystallization or initiating and stabilizing non-equilibrium crystal polymorphs and morphologies through interactions between anionic moieties and cations in solution or at mineralizing surfaces. In particular, biomolecules that present carboxyl groups to the growing crystal have been implicated as primary modulators of growth. Here we review the results from a combination of in situ atomic force microscopy (AFM) and molecular modeling (MM) studies to investigate the effect of specific interactions between carboxylate-rich biomolecules and atomic steps on crystal surfaces during the growth of carbonates, oxalates and phosphates of calcium. Specifically, we how the growth kinetics and morphology depend on the concentration of additives that include citrate, simple amino acids, synthetic Asp-rich polypeptides, and naturally occurring Asp-rich proteins found in both functional and pathological mineral tissues. The results reveal a consistent picture of shape modification in which stereochemical matching of modifiers to specific atomic steps drives shape modification. Inhibition and other changes in growth kinetics are shown to be due to a range of mechanisms that depend on chemistry and molecular size. Some effects are well described by classic crystal growth theories, but others, such as step acceleration due to peptide charge and hydrophylicity, were previously unrealized

  1. Atomic force microscopy measurements of crystal nucleation and growth rates in thin films of amorphous Te alloys

    Science.gov (United States)

    Kalb, J.; Spaepen, F.; Wuttig, M.

    2004-06-01

    Ex situ atomic force microscopy in combination with a high-precision furnace has been employed for a systematic study of crystallization kinetics of sputtered amorphous Ag0.055In0.065Sb0.59Te0.29, Ge4Sb1Te5, and Ge2Sb2Te5 thin films used for optical data storage. Direct observation of crystals enabled us to establish the temperature dependence of the crystal nucleation rate and crystal growth velocity around 150°C. While these alloys exhibited similar crystal growth characteristics, the crystal nucleation behavior of Ag0.055In0.065Sb0.59Te0.29 differed significantly from that of Ge4Sb1Te5 and Ge2Sb2Te5. These observations provide an explanation for the different recrystallization mechanisms observed upon laser heating of amorphous marks.

  2. The growth of sapphire single crystals

    Directory of Open Access Journals (Sweden)

    STEVAN DJURIC

    2001-06-01

    Full Text Available Sapphire (Al2O3 single crystals were grown by the Czochralski technique both in air and argon atmospheres. The conditions for growing sapphire single crystals were calculated by using a combination of Reynolds and Grashof numbers. Acritical crystal diameter dc = 20 mm and the critical rate of rotation wc = 20 rpm were calculated from the hydrodynamics of the melt. The value of the rate of crystal growth was experimentally found to be 3.5 mm/h. According to our previous experiments, it was confirmed that three hours exposures to conc. H3PO4 at 593 K was suitable for chemical polishing. Also, three hours exposure to conc.H3PO4 at 523 K was found to be a suitable etching solution. The lattice parameters a = 0.47573 nm and c = 1.29893 nm were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

  3. Barrier for Continuous-Crystal-Growth Crucible

    Science.gov (United States)

    Skutch, M. E.; Piotrowski, P. A.

    1983-01-01

    Properly designed openings permit free flow of melt while restraining pellets. Redesigned partition between growth region and melt-replenishment region of crystal-growth crucible makes it less likely crucible will run out of feed material in middle of cycle. Supply of molten silicon is maintained by addition of silicon pellets to compartment at one end of heated crucible, and partition or barrier is required to hold pellets while allowing melted silicon to flow from compartment.

  4. Czochralski growth and properties of scintillating crystals

    Czech Academy of Sciences Publication Activity Database

    Yoshikawa, A.; Chani, V.; Nikl, Martin

    2013-01-01

    Roč. 124, č. 2 (2013), s. 250-264 ISSN 0587-4246 R&D Projects: GA MŠk LH12150 Institutional support: RVO:68378271 Keywords : Czochralski method * single crystal growth * oxide * fluoride * Ce 3+ * Pr 3+ Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.604, year: 2013

  5. Meniscus Imaging for Crystal-Growth Control

    Science.gov (United States)

    Sachs, E. M.

    1983-01-01

    Silicon crystal growth monitored by new video system reduces operator stress and improves conditions for observation and control of growing process. System optics produce greater magnification vertically than horizontally, so entire meniscus and melt is viewed with high resolution in both width and height dimensions.

  6. Growth and characterization of nonlinear optical single crystals: bis ...

    Indian Academy of Sciences (India)

    methoxy benzoate (C4MB) single crystals were successfully grown by the slow evaporation solution growth technique. The harvested crystals were subjected to single-crystal X-ray diffraction, spectral, optical, thermal and mechanical studies in ...

  7. Temperature profiles in high gradient furnaces

    Science.gov (United States)

    Fripp, A. L.; Debnam, W. J.; Woodell, G. A.; Berry, R.; Crouch, R. K.; Sorokach, S. K.

    1989-01-01

    Accurate temperature measurement of the furnace environment is very important in both the science and technology of crystal growth as well as many other materials processing operations. A high degree of both accuracy and precision is acutely needed in the directional solidification of compound semiconductors in which the temperature profiles control the freezing isotherm which, in turn, affects the composition of the growth with a concomitant feedback perturbation on the temperature profile. Directional solidification requires a furnace configuration that will transport heat through the sample being grown. A common growth procedure is the Bridgman Stockbarger technique which basically consists of a hot zone and a cold zone separated by an insulator. In a normal growth procedure the material, contained in an ampoule, is melted in the hot zone and is then moved relative to the furnace toward the cold zone and solidification occurs in the insulated region. Since the primary path of heat between the hot and cold zones is through the sample, both axial and radial temperature gradients exist in the region of the growth interface. There is a need to know the temperature profile of the growth furnace with the crystal that is to be grown as the thermal load. However it is usually not feasible to insert thermocouples inside an ampoule and thermocouples attached to the outside wall of the ampoule have both a thermal and a mechanical contact problem as well as a view angle problem. The objective is to present a technique of calibrating a furnace with a thermal load that closely matches the sample to be grown and to describe procedures that circumvent both the thermal and mechanical contact problems.

  8. Crystal growth and structural analysis of zirconium sulphoselenide ...

    Indian Academy of Sciences (India)

    Wintec

    tion for the growth of these crystals is given. The stoichiometry of the grown crystals ... 646. Table 1. Growth parameters of zirconium sulphoselenide single crystal grown using chemical vapour transport technique. Physical .... The needle shaped, black or radish shining layered single crystals of zirconium sulphoselenide ...

  9. Crystallization and Growth of Colloidal Nanocrystals

    CERN Document Server

    Leite, Edson Roberto

    2012-01-01

    Since the size, shape, and microstructure of nanocrystalline materials strongly impact physical and chemical properties, the development of new synthetic routes to  nanocrystals with controlled composition and morphology is a key objective of the nanomaterials community. This objective is dependent on control of the nucleation and growth mechanisms that occur during the synthetic process, which in turn requires a fundamental understanding of both classical nucleation and growth and non-classical growth processes in nanostructured materials.  Recently, a novel growth process called Oriented Attachment (OA) was identified which appears to be a fundamental mechanism during the development of nanoscale  materials. OA is a special case of aggregation that provides an important route by which nanocrystals grow, defects are formed, and unique—often symmetry-defying—crystal morphologies can be produced. This growth mechanism involves reversible self-assembly of primary nanocrystals followed by reorientati...

  10. Engineering crystal growth of calcium hydrogenphosphate dihydrate

    Energy Technology Data Exchange (ETDEWEB)

    Sikiric, M.; Babic-Ivancic, V. [Institut Rudjer Boskovic, Zagreb (Croatia); Milat, O. [Zagreb Univ. (Croatia). Inst. za Fiziku; Sarig, S.; Fueredi-Milhofer, H. [Hebrew Univ., Jerusalem (Israel). Inst. of Applied Chemistry

    2001-07-01

    The factors underlying calcium hydrogenphosphate dihydrate (CaHPO{sub 4}.2H{sub 2}O, DCPD) interactions with several structurally different additives: glutamic and aspartic acid, sodium citrate, hexaammonium tetrapolyphosphate, calcium phytate and polyaspartic acid were studied. DCPD crystals were prepared under controlled conditions by fast mixing of the anionic and cationic reactant solutions and subsequent growth without further stirring in the course of 24 hours at 37 C. The initial conditions were c(CaCl{sub 2}) = c(Na{sub 2}HPO{sub 4}) = 0.021 mol dm{sup -3}, c(NaCl) = 0.3 mol dm{sup -3}, pH{sub i} 5.5. The respective additive was added to the anionic component prior to pH adjustment. Crystals were characterized by X-ray diffraction, while their morphology was observed by optical and scanning electron microscopy (SEM). The Miller indices of the crystal faces were determined from SEM micrographs, after the orientation of the most prominent face was ascertained by the Weissenberg method. Mechanism of additive-DCPD crystals interaction depends on size and structure of additive molecule, structural fit between organic molecule and the ionic structure of particular crystal face. Small molecules (ions) specifically adsorb on lateral faces by electrostatic interactions, while macromolecules and molecules with hindered structure specifically adsorb on dominant (010) face, for which certain degree of structural fit is necessary. (orig.)

  11. Studying Crystal Growth With the Peltier Effect

    Science.gov (United States)

    Larsen, David J., Jr.; Dressler, B.; Silberstein, R. P.; Poit, W. J.

    1986-01-01

    Peltier interface demarcation (PID) shown useful as aid in studying heat and mass transfer during growth of crystals from molten material. In PID, two dissimilar "metals" solid and liquid phases of same material. Current pulse passed through unidirectionally solidifying sample to create rapid Peltier thermal disturbance at liquid/solid interface. Disturbance, measured by thermocouple stationed along path of solidification at or near interface, provides information about position and shape of interface.

  12. (PCG) Protein Crystal Growth Human Serum Albumin

    Science.gov (United States)

    1989-01-01

    (PCG) Protein Crystal Growth Human Serum Albumin. Contributes to many transport and regulatory processes and has multifunctional binding properties which range from various metals, to fatty acids, hormones, and a wide spectrum of therapeutic drugs. The most abundant protein of the circulatory system. It binds and transports an incredible variety of biological and pharmaceutical ligands throughout the blood stream. Principal Investigator on STS-26 was Larry DeLucas.

  13. Optical Investigation of Nanoconfined Crystal Growth

    Science.gov (United States)

    Kohler, F.; Dysthe, D. K.

    2015-12-01

    Crystals growing in a confined space exert forces on their surroundings. This crystallization force causes deformation of solids and is therefore particularly relevant for the comprehension of geological processes such as replacement and weathering [1]. In addition, these forces are relevant for the understanding of damages in porous building materials caused by crystallization, which is of great economical importance and fundamental for methods that can help to preserve our cultural heritage [2,3]. However, the exact behavior of the growth and the dissolution process in close contact to an interface are still not known in detail. The crystallization, the dissolution and the transport of material is mediated by a nanoconfined water film. We observe brittle NaClO3 crystals growing against a glass surface by optical methods such as reflective interference contrast microscopy (RICM) [4]. In order to carefully control the supersaturation of the fluid close to the crystal interface, a temperature regulated microfluidic system is used (fig. A). The interference based precision of RICM enables to resolve distance variations down to the sub nanometer range without any unwanted disturbances by the measuring method. The combination of RICM with a sensitive camera allows us to observe phenomena such as periodic, wavelike growth of atomic layers. These waves are particularly obvious when observing the difference between two consecutive images (fig. B). In contradiction to some theoretical results, which predict a smooth interface, some recent experiments have shown that the nanoconfined growth surfaces are rough. In combination with theoretical studies and Kinetic Monte Carlo simulations we aim at providing more realistic descriptions of surface energies and energy barriers which are able to explain the discrepancies between experiments and current theory. References:[1] Maliva, Diagenetic replacement controlled by force of crystallization, Geology, August (1988), v. 16 [2] G

  14. The Effect of Protein Impurities on Lysozyme Crystal Growth

    Science.gov (United States)

    Judge, Russell A.; Forsythe, Elizabeth L.; Pusey, Marc L.

    1998-01-01

    While bulk crystallization from impure solutions is used industrially as a purification step for a wide variety of materials, it is a technique that has rarely been used for proteins. Proteins have a reputation for being difficult to crystallize and high purity of the initial crystallization solution is considered paramount for success in the crystallization. Although little is written on the purifying capability of protein crystallization or of the effect of impurities on the various aspects of the crystallization process, recent published reports show that crystallization shows promise and feasibility as a purification technique for proteins. In order to further examine the issue of purity in macromolecule crystallization this study investigates the effect of the protein impurities, avidin, ovalbumin and conalbumin, at concentrations up to 50%, on the solubility, crystal face growth rates and crystal purity, of the protein lysozyme. Solubility was measured in batch experiments while a computer controlled video microscope system was used to measure the f {101} and {101} lysozyme crystal face growth rates. While little effect was observed on solubility and high crystal purity was obtained (>99.99%), the effect of the impurities on the face growth rates varied from no effect to a significant face specific effect leading to growth cessation, a phenomenon that is frequently observed in protein crystal growth. The results shed interesting light on the effect of protein impurities on protein crystal growth and strengthen the feasibility of using crystallization as a unit operation for protein purification.

  15. Crystal growth of emerald by flux method

    International Nuclear Information System (INIS)

    Inoue, Mikio; Narita, Eiichi; Okabe, Taijiro; Morishita, Toshihiko.

    1979-01-01

    Emerald crystals have been formed in two binary fluxes of Li 2 O-MoO 2 and Li 2 O-V 2 O 5 using the slow cooling method and the temperature gradient method under various conditions. In the flux of Li 2 O-MoO 3 carried out in the range of 2 -- 5 of molar ratios (MoO 3 /Li 2 O), emerald was crystallized in the temperature range from 750 to 950 0 C, and the suitable crystallization conditions were found to be the molar ratio of 3 -- 4 and the temperature about 900 0 C. In the flux of Li 2 O-V 2 O 5 carried out in the range of 1.7 -- 5 of molar ratios (V 2 O 5 /Li 2 O), emerald was crystallized in the temperature range from 900 to 1150 0 . The suitable crystals were obtained at the molar ratio of 3 and the temperature range of 1000 -- 1100 0 C. The crystallization temperature rised with an increase in the molar ratio of the both fluxes. The emeralds grown in two binary fluxes were transparent green, having the density of 2.68, the refractive index of 1.56, and the two distinct bands in the visible spectrum at 430 and 600nm. The emerald grown in Li 2 O-V 2 O 5 flux was more bluish green than that grown in Li 2 O-MoO 3 flux. The size of the spontaneously nucleated emerald grown in the former flux was larger than the latter, when crystallized by the slow cooling method. As for the solubility of beryl in the two fluxes, Li 2 O-V 2 O 5 flux was superior to Li 2 O-MoO 3 flux whose small solubility of SiO 2 caused an experimental problem to the temperature gradient method. The suitability of the two fluxes for the crystal growth of emerald by the flux method was discussed from the view point of various properties of above-mentioned two fluxes. (author)

  16. Historical review of quartz crystal growth

    Science.gov (United States)

    Iwasaki, Fumiko; Iwasaki, Hideo

    2002-04-01

    The history of quartz crystal growth is reviewed from the origin to the industrialization. The developing process of growth techniques is divided into the following three stages: (1) The fundamental work based on the mineralogical genetic view point, which was performed in Italy during the end of the 19th to the beginning of the 20th centuries. (2) The works to attempt the industrial application made in Germany and in England during World War II. (3) The industrialization of quartz growth after World War II. These were initiated in England, in USA and independently in Russia. The highest mass production process was developed in Japan. The historical flow is traced by the interview of several persons based on the original references.

  17. Bridgman growth of large-aperture yttrium calcium oxyborate crystal

    International Nuclear Information System (INIS)

    Wu, Anhua; Jiang, Linwen; Qian, Guoxing; Zheng, Yanqing; Xu, Jun; Shi, Erwei

    2012-01-01

    Highlights: ► YCOB is a novel non-linear optical crystal possessing good thermal, mechanical and nonlinear optical properties. ► Large size crystal growth is key technology question for YCOB crystal. ► YCOB crystals 3 in. in diameter were grown with modified vertical Bridgman method. ► It is a more effective growth method to obtain large size and high quality YCOB crystal. -- Abstract: Large-aperture yttrium calcium oxyborate YCa 4 O(BO 3 ) 3 (YCOB) crystals with 3 in. in diameter were grown with modified vertical Bridgman method, and the large crystal plate (63 mm × 68 mm × 20 mm) was harvested for high-average power frequency conversion system. The crack, facet growth and spiral growth can be effectively controlled in the as-grown crystal, and Bridgman method displays more effective in obtain large size and high quality YCOB crystal plate than Czochralski technique.

  18. Growth of the (001) face of borax crystals

    OpenAIRE

    Suharso, Suharso

    2010-01-01

    he growth rates of borax crystals from aqueous solutions in the (001) direction at various relative supersaturations were measured using in situ cell optical microscopy method. The result shows that the growth mechanism of the (001) face of borax crystal at temperature of 20 °C is spiral growth mechanism.   Keywords: Growth mechanism, borax.

  19. Growth features of ammonium hydrogen d-tartrate single crystals

    Indian Academy of Sciences (India)

    Unknown

    Ammonium hydrogen d-tartrate (d-AHT) single crystals were grown in silica gel. The growth fea- tures of these crystals with variation of parameters like specific gravity of the gel, gel pH, acid concentrations, concentration of the feed solution and gel age were studied in detail. Keywords. d-AHT single crystals; growth features ...

  20. Growth of strontium oxalate crystals in agar–agar gel

    Indian Academy of Sciences (India)

    Crystal growth; strontium oxalate; X-ray spectroscopy; FT–IR. 1. Introduction. The growth of single crystals of various substances has gained considerable attention of several investigators. Sophisticated and strenuous equipments have been devel- oped and employed for growing a wide variety of crystals; either may be due ...

  1. Seed crystal in growth of KDP single crystal for optical harmonic generation

    International Nuclear Information System (INIS)

    Shimomura, Osamu

    1985-01-01

    As for the crystal growth of KDP for optical harmonic generation, the employment of (101) seed crystal plate could reduce crystal growth period in comparison with the employment of conventional (001) seed crystal plate except the case of low phase matching angle. This paper describes seed crystal in the case of types I and II of phase matching, evaluation of minimum crystal volume to cut necessary volume crystal plate for optical harmonic generation in the case of types I and II for (001) and (101) crystal plates, results and discussion of numerical analysis of KDP crystal growth for the above-mentioned cases and experimental results of actual KDP crystal growth. It was clarified from these examinations that the use of a (101) crystal plate as a seed showed faster crystal growth regardless of theta m, a phase matching angle. It was also shown that the minimum crystal volume to cut the necessary volume crystal for optical harmonic generation became less by employing a (101) crystal plate than employing a (001) crystal in the case of high phase matching angle, namely theta m > 23.7 0 for type I and theta m > 11.6 0 for type II. Example calculations showed that 54.4 % of crystal growth period for type I and 33.8 % of that for type II was needed for the (101) seed crystal plate in comparison with the case of the (001) seed crystal plate. It was speculated that this conclusion might be applicable also for DKDP or ADP crystals growth. (Takagi, S.)

  2. The impact of space research on semiconductor crystal growth technology

    Science.gov (United States)

    Witt, A. F.

    1983-01-01

    Crystal growth experiments in reduced gravity environment and related ground-based research have contributed significantly to the establishment of a scientific basis for semiconductor growth from the melt. NASA-sponsored research has been instrumental in the introduction of heat pipes for heat and mass transfer control in crystal growth and in the development of magnetic field induced melt stabilization, approaches primarily responsible for recent advances in crystal growth technology.

  3. Materials of construction for silicon crystal growth

    Science.gov (United States)

    Leipold, M. H.; Odonnell, T. P.; Hagan, M. A.

    1980-01-01

    The performance of materials for construction and in contact with molten silicon for crystal growth is presented. The basis for selection considers physical compatibility, such as thermal expansion and strength, as well as chemical compatibility as indicated by contamination of the silicon. A number of new high technology materials are included as well as data on those previously used. Emphasis is placed on the sources and processing of such materials in that results are frequently dependent on the way a material is prepared as well as its intrinsic constituents.

  4. Solid state single crystal growth of three-dimensional faceted LaFeAsO crystals

    Science.gov (United States)

    Kappenberger, Rhea; Aswartham, Saicharan; Scaravaggi, Francesco; Blum, Christian G. F.; Sturza, Mihai I.; Wolter, Anja U. B.; Wurmehl, Sabine; Büchner, Bernd

    2018-02-01

    Solid state single crystal growth (SSCG) is a crystal growth technique where crystals are grown from a polycrystalline matrix. Here, we present single crystals of the iron pnictide LaFeAsO grown via SSCG using NaAs as a liquid phase to aid crystallization. The size of the as-grown crystals are up to 2 × 3 × 0.4 mm3. Typical for this method, but very uncommon for crystals of the pnictide superconductors and especially for the oxypnictides, the crystals show pronounced facets caused by considerable growth in c direction. The crystals were characterized regarding their composition, structure, magnetic, and thermodynamic properties. This sets the stage for further measurements for which single crystals are crucial such as any c axis and reciprocal space dependent measurements.

  5. Improvement of metastable crystal of acetaminophen via control of crystal growth rate

    Science.gov (United States)

    Nii, Kosuke; Maruyama, Mihoko; Okada, Shino; Adachi, Hiroaki; Takano, Kazufumi; Murakami, Satoshi; Yoshikawa, Hiroshi Y.; Matsumura, Hiroyoshi; Inoue, Tsuyoshi; Imanishi, Masayuki; Tsukamoto, Katsuo; Yoshimura, Masashi; Mori, Yusuke

    2018-03-01

    We showed a relationship among the growth rate, defect generation process, and stability of the metastable phase form II crystal of acetaminophen. Appropriate control of the form II crystal growth rate via slow cooling and nanosize crystal seeding not only suppressed the defect formation but improved the crystallinity of form II. The boundary condition between the interfacial control and transport control was determined based on the relationship between the crystal growth rate and supersaturation. The nanosize crystal seeds met the conditions of interfacial control; thus, the serious defects were suppressed. Finally, better temporal stability of the form II crystal was achieved.

  6. Convective diffusion in protein crystal growth

    Science.gov (United States)

    Baird, J. K.; Meehan, E. J.; Xidis, A. L.; Howard, S. B.

    1986-08-01

    We considered a protein crystal in the form of a flat plate suspended in its parent solution so that the normal to the largest face was perpendicular to the acceleration due to gravity. For simplicity, the protein concentration in the solution adjacent to the plate was taken to be the equilibrium solubility. The bulk of the solution was supersaturated, however, which gave rise to a horizontal concentration gradient driving fluid toward the plate. We also took into account the diffusion of the dissolved protein with respect to the moving fluid. In the boundary layer next to the plate, we solved the Navier-Stokes equation and the equation for convective diffusion to determine the flow velocity and the protein mass flux. We found that, because of the convection, the local rate of growth of the plate varied strongly with depth. The variation was diminished by a factor of 1/30 when the local gravity was reduced from g to 10 -6g as occurs aboard the Space Shuttle in earth orbit. For an aqueous solution of lysozyme at a concentration of 40 mg/ml, the boundary layer at the top of a 1 mm high crystal has a thickness of 80 μm in earths gravity and 2570 μm in 10 -6g. We examined the optical transmission of the boundary layer and compared it with the "haloes" observed by Feher et al. about growing hemispherical crystals of lysozyme.

  7. Advances in the understanding of crystal growth mechanisms

    CERN Document Server

    Nishinaga, T; Harada, J; Sasaki, A; Takei, H

    1997-01-01

    This book contains the results of a research project entitled Crystal Growth Mechanisms on an Atomic Scale, which was carried out for 3 years by some 72 reseachers. Until recently in Japan, only the technological aspects of crystal growth have been emphasized and attention was paid only to its importance in industry. However the scientific aspects also need to be considered so that the technology of crystal growth can be developed even further. This project therefore aimed at understanding crystal growth and the emphasis was on finding growth mechanisms on an atomic scale.

  8. In situ inward epitaxial growth of bulk macroporous single crystals.

    Science.gov (United States)

    Chen, Chenlong; Sun, Shujing; Chou, Mitch M C; Xie, Kui

    2017-12-19

    The functionalities of porous materials could be significantly enhanced if the materials themselves were in single-crystal form, which, owing to structural coherence, would reduce electronic and optical scattering effects. However, growing macroporous single crystals remains a fundamental challenge, let alone manufacturing crystals large enough to be of practical use. Here we demonstrate a straightforward, inexpensive, versatile method for creating macroporous gallium nitride single crystals on a centimetre scale. The synthetic strategy is built upon a disruptive crystal growth mechanism that utilises direct nitridation of a parent LiGaO 2 single crystal rendering an inward epitaxial growth process. Strikingly, the resulting single crystals exhibit electron mobility comparable to that for bulk crystals grown by the conventional sodium flux method. This approach not only affords control of both crystal and pore size through synthetic modification, but proves generic, thus opening up the possibility of designing macroporous crystals in a wealth of other materials.

  9. Growth of lead molybdate crystals by vertical Bridgman method

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The growth of PbMoO4 crystals by the modified Bridgman method has been reported in this paper. The feed material with strict stoichiometric composition is desirable for the Bridgman growth of the crystals. The continuous composition change of the melts during growth can be avoided because the volatiliza-.

  10. Anion-switchable supramolecular gels for controlling pharmaceutical crystal growth

    Science.gov (United States)

    Foster, Jonathan A.; Piepenbrock, Marc-Oliver M.; Lloyd, Gareth O.; Clarke, Nigel; Howard, Judith A. K.; Steed, Jonathan W.

    2010-12-01

    We describe the use of low-molecular-weight supramolecular gels as media for the growth of molecular crystals. Growth of a range of crystals of organic compounds, including pharmaceuticals, was achieved in bis(urea) gels. Low-molecular-weight supramolecular gelators allow access to an unlimited range of solvent systems, in contrast to conventional aqueous gels such as gelatin and agarose. A detailed study of carbamazepine crystal growth in four different bis(urea) gelators, including a metallogelator, is reported. The crystallization of a range of other drug substances, namely sparfloxacin, piroxicam, theophylline, caffeine, ibuprofen, acetaminophen (paracetamol), sulindac and indomethacin, was also achieved in supramolecular gel media without co-crystal formation. In many cases, crystals can be conveniently recovered from the gels by using supramolecular anion-triggered gel dissolution; however, crystals of substances that themselves bind to anions are dissolved by them. Overall, supramolecular gel-phase crystallization offers an extremely versatile new tool in pharmaceutical polymorph screening.

  11. Beginner’s guide to flux crystal growth

    CERN Document Server

    Tachibana, Makoto

    2017-01-01

    This book introduces the principles and techniques of crystal growth by the flux method, which is arguably the most useful way to obtain millimeter- to centimeter-sized single crystals for physical research. As it is possible to find an appropriate solvent (“flux”) for nearly all inorganic materials, the flux method can be applied to the growth of many crystals ranging from transition metal oxides to intermetallic compounds. Both important principles and experimental procedures are described in a clear and accessible manner. Practical advice on various aspects of the experiment, which is not readily available in the literature, will assist the beginning graduate students in setting up the lab and conducting successful crystal growth. The mechanisms of crystal growth at an elementary level are also provided to better understand the techniques and to help in assessing the quality of the crystals. The book also contains many photographs of beautiful crystals with important physical properties of current inte...

  12. Growth of Ce-Doped LSO Single Crystals by Stockbarger-Bridgman Modified Crystallization Method

    International Nuclear Information System (INIS)

    Namtalishvili, M.; Sanadze, T.; Basharuli, N.; Magalashvili, P.; Mikaberidze, A.; Razmadze, Z.; Gabeskiria, M.

    2006-01-01

    The modified Stockbarger-Bridgman method was suggested for the growth of optically perfect LSO:Ce single crystals. Our investigations have shown that the most perfect crystals are grown by by the horizontally directed crystallization. In this case the elements of directional crystallyzation are combined with the zone melting. Crystallization is carried out in the conditions of sufficiently developed mirror of meltin. As a result in this case the chemical purity of grown crystals increases. (author)

  13. Unidirectional seeded single crystal growth from solution of benzophenone

    Science.gov (United States)

    Sankaranarayanan, K.; Ramasamy, P.

    2005-07-01

    A novel crystal growth method has been established for the growth of single crystal with selective orientation at room temperature. Using volatile solvent, the saturated solution containing the material to be crystallized was taken in an ampoule and allowed to crystallize by slow solvent evaporation assisted with a ring heater. The orientation of the growing crystal was imposed by means of a seed fixed at the bottom of the ampoule. By selecting a suitable ring heater voltage and by controlling the ring heater voltage, nucleation and the growth rate of the crystal were controlled more effectively. By employing this novel method, benzophenone single crystal ingots of diameters 10 and 20 mm and length more than 50 mm were successfully grown using xylene as solvent. The ease in scaling up of diameter from 10 to 20 mm shows the vital advantage of this technique. It was possible to achieve solute-crystal conversion efficiency of 100 percent. The grown benzophenone crystal was characterized by FTIR, TG and DTA, powder X-ray diffraction, X-ray rocking curve, optical transmission study and powder SHG measurement. The results show that the crystal quality is at least as good as the quality of the crystal grown by other known methods. Also, microbial growth was naturally avoided in this method, as the fresh solution is constantly made available for the growing crystal.

  14. Modeling the growth rates of tetragonal lysozyme crystals

    Science.gov (United States)

    Li, Meirong; Nadarajah, Arunan; Pusey, Marc L.

    1995-11-01

    Although the faceted growth of tetragonal lysozyme crystals is known to occur by 2D nucleation and dislocation-led growth, the measured growth rates do not follow model predictions based on these mechanisms. One possible reason for this deviation is that these models ignore the highly aggregated state of lysozyme in supersaturated solutions. In this study a growth mechanism for tetragonal lysozyme crystals involving aggregation reactions leading to the formation of the growth unit, mass transport of the growth unit to the crystal interface and faceted crystal growth by growth unit addition, is proposed. The distribution of aggregates in lysozyme nutrient solutions were determined from the equilibrium aggregation reactions and comparisons were made with growth rates calculated from the model based on the proposed mechanism and the measured growth rate data. The results indicated than an octamer corresponding to the tetragonal crystal unit cell was the most likely growth unit for the process. Remarkably good fits were obtained with this model to the measured growth rate data for three sets of pH and salt concentrations, suggesting the validity of the proposed mechanism. The values of the kinetic coefficient for the step velocity was in the range for small molecule crystal growth and the heats of reaction compared well with that obtained from lysozyme solubility data. The results presented here suggest that the inorganic and protein crystal growth processes are quite similar in many ways. Lysozyme crystal growth differs primarily due to growth by an aggregate growth unit and in the effect of nutrient solution conditions on the protein aggregation process.

  15. A versatile Czochralski crystal growth system with automatic diameter control

    Science.gov (United States)

    Aggarwal, M. D.; Metzl, R.; Wang, W. S.; Choi, J.

    1995-07-01

    A versatile Czochralski crystal pulling system with automatic diameter control for the growth of nonlinear optical oxide crystals is discussed. Pure and doped bulk single crystals of bismuth silicon oxide (Bi12SiO20) have been successfully grown using this system. The system consists of a regular Czochralski type pulling system with provision for continuous weighing of the growing crystal to provide feedback for power control.

  16. Scientific/Technical Report: Improvement in compensation and crystal growth of cadmium zinc telluride radiation detectors

    International Nuclear Information System (INIS)

    Kelvin G. Lynn; Kelly A. Jones

    2007-01-01

    Comparison of actual accomplishments with goals and objectives: (1) Growth of 12 ingots--Washington State University (WSU) more than met this goal for the project by growing 12 final ingots for the year. Nine of the twelve crystal growth ingots resolved gamma radiation at room temperature. The other three ingots where resistivity of ∼ 3 x 10 8 Ohm*cm for CG32a, CG36, and CG42 lower than expected, however none of these were tried with blocking contacts. All ingots were evaluated from tip to heel. In these three cases, the group III, dopant Aluminum (Al) was not detected to a level to compensate the Cd vacancies in the cadmium zinc telluride (CZT) thus the ingots were lower resistivity. The nine ingots that were successful radiation detectors averaged a bulk resistivity of 1.25 x 10 10 Ohm*cm and with a average μτ product for electrons of ∼ 2 x 10 -4 cm 2 /V with a 1/4 microsecond shaping time with samples ∼2 mm in thickness. (2) Attempt new compensations techniques--WSU also met this goal. Several doping schemes were attempted and investigated with various amounts of excess Tellurium added to the growth. The combination of Al and Erbium (Er) were first attempted for these ingots and subsequently CG34 was grown with Al, Er and Holmium. These compensation techniques produced radiation detectors and are currently under investigation. These growths were made with significant different doping levels to determine the affect of the dopants. CG43 was doped with Indium and Er. Indium was introduced instead of Al to determine if Indium is more soluble than Al for CZT and was less oxidized. This may decrease the amount of low resistivity ingots grown by doping with Indium instead of Al. (3) Grow large single crystals--Several changes in approach occurred in the crystal growth furnace. Steps were taken to maximize the crystal growth interface during growth by modifying liners, quartz, heat sinks, crucibles and various growth steps and temperature profiles. CG39 ingot

  17. Growth and fabrication of large size sodium iodide crystal scintillator

    International Nuclear Information System (INIS)

    Sabharwal, S.C.; Karandikar, S.C.; Mirza, T.; Ghosh, B.; Deshpande, R.Y.

    1979-01-01

    The growth of 80 - 135 mm dia. Sodium iodide crystals activated with thallium is described in the present report. The growth is effected in a glazed porcelain crucible in a protective ambient of dry nitrogen. The technical details of the equipment developed have been fully described. The results of measurements on the rate of growth of crystal and the optimization of different growth parameters are reported. The dependence of various factors upon the performance characteristics of the scintillator detectors made using these crystals is also discussed. The energy resolution obtained for a typical detector of dimensions 76 mm dia x 76 mm ht. is 10 percent. (auth.)

  18. A Comparative Study of Impurity Effects on Protein Crystallization : Diffusive versus Convective Crystal Growth

    NARCIS (Netherlands)

    Adawy, Alaa; van der Heijden, Esther G. G.; Hekelaar, Johan; van Enckevort, Willem J. P.; de Grip, Willem J.; Vlieg, Elias

    The incorporation of impurities during protein crystallization is one of the main obstacles that prevents the growth of high quality crystals. Mass transport has been shown to affect the incorporation of impurities. Here we used a special growth configuration that enables the simultaneous

  19. Growth and Characterization on PMN-PT-Based Single Crystals

    Directory of Open Access Journals (Sweden)

    Jian Tian

    2014-07-01

    Full Text Available Lead magnesium niobate—lead titanate (PMN-PT single crystals have been successfully commercialized in medical ultrasound imaging. The superior properties of PMN-PT crystals over the legacy piezoelectric ceramics lead zirconate titanate (PZT enabled ultrasound transducers with enhanced imaging (broad bandwidth and improved sensitivity. To obtain high quality and relatively low cost single crystals for commercial production, PMN-PT single crystals were grown with modified Bridgman method, by which crystals were grown directly from stoichiometric melt without flux. For ultrasound imaging application, [001] crystal growth is essential to provide uniform composition and property within a crystal plate, which is critical for transducer performance. In addition, improvement in crystal growth technique is under development with the goals of improving the composition homogeneity along crystal growth direction and reducing unit cost of crystals. In recent years, PIN-PMN-PT single crystals have been developed with higher de-poling temperature and coercive field to provide improved thermal and electrical stability for transducer application.

  20. High-quality single crystals for neutron experiments

    Indian Academy of Sciences (India)

    To make headway on any problem in physics, high-quality single crystals are required. In this talk, special emphasis will be placed on the crystal growth of various oxides (superconductors and magnetic materials), borides and carbides using the image furnaces at Warwick. The floating zone method of crystal growth used in ...

  1. Plant Growth and Water Purification of Porous Vegetation Concrete Formed of Blast Furnace Slag, Natural Jute Fiber and Styrene Butadiene Latex

    Directory of Open Access Journals (Sweden)

    Hwang-Hee Kim

    2016-04-01

    Full Text Available The purpose of this study is to investigate porous vegetation concrete formed using the industrial by-products blast furnace slag powder and blast furnace slag aggregates. We investigated the void ratio, compressive strength, freeze–thaw resistance, plant growth and water purification properties using concretes containing these by-products, natural jute fiber and latex. The target performance was a compressive strength of ≥12 MPa, a void ratio of ≥25% and a residual compressive strength of ≥80% following 100 freeze–thaw cycles. Using these target performance metrics and test results for plant growth and water purification, an optimal mixing ratio was identified. The study characterized the physical and mechanical properties of the optimal mix, and found that the compressive strength decreased compared with the default mix, but that the void ratio and the freeze–thaw resistance increased. When latex was used, the compressive strength, void ratio and freeze–thaw resistance all improved, satisfying the target performance metrics. Vegetation growth tests showed that plant growth was more active when the blast furnace slag aggregate was used. Furthermore, the use of latex was also found to promote vegetation growth, which is attributed to the latex forming a film coating that suppresses leaching of toxic components from the cement. Water purification tests showed no so significant differences between different mixing ratios; however, a comparison of mixes with and without vegetation indicated improved water purification in terms of the total phosphorus content when vegetation had been allowed to grow.

  2. General approach to Monte Carlo simulation of crystal growth

    International Nuclear Information System (INIS)

    Cherepanova, T.A.

    1986-01-01

    This paper presents a statistical-mechanic description of the techniques valid for simulating crystal growth both in single-component and in multi-component crystals, the work being based on the ideas previously developed. A lattice model of a two-phase crystal-melt system is considered. The authors consider general features of crystallization in metal type bindary systems (growth on atomically rough (001) faces) by using simulation techniques and by solving kinetic equations. They choose as a model those systems with primitive cubic lattice symmetry

  3. Growth and defects of explosives crystals

    Science.gov (United States)

    Cady, H. H.

    Large single crystals of PETN, RDX, and TNT can be grown easily from evaporating ethyl acetate solutions. The crystals all share a similar type of defect that may not be commonly recognized. The defect generates conical faces, ideally mosaic crystals, and may account for the 'polymorphs' of TNT and detonator grades of PETN. TATB crystals manufactured by the amination of trichlorotrinitrobenzene in dry toluene entrain two forms of ammonium chloride. One of these forms causes 'worm holes' in the TATB crystals that may be the reason for its unusually low failure diameters. Strained HMX crystals form mechanical twins that can spontaneously revert back to the untwinned form when the straining force is removed. Large strains or temperatures above 100 C lock in the mechanical twins.

  4. Influence of the soluble fraction of blast furnace slag on the growth of some algae

    Energy Technology Data Exchange (ETDEWEB)

    Tokuda, H.

    1977-01-01

    The sea water-soluble fraction of the pulverized slag was prepared in anaerobic condition, and mixed with a basal medium in various ratios for preparation of a culture medium, on which the growth of a diatom, Skeletonema costatum, was suppressed. The inhibitory effect of the soluble fraction to this alga was reduced to a certain degree when the culture medium had been aerated with nitrogen preceding inoculation. The growth of Skel. costatum was also inhibited on the basal medium containing the untreated slag powder in various amounts, while it was stimulated when the slag powder was washed for several days before addition to the basal medium. The soluble fraction of the slag affected unfavorably the growth of a laver, Porphyra yezoensis, also. A diatom, Nitzschia closterium, was able to grow closely adhering to the slag powder. The inhibitory effect of the soluble fraction of the slag to algae seems to be caused largely by potassium or sodium sulfide, and slightly by sulfur oxides and some heavy metals dissolved in trace amounts.

  5. Development of novel growth methods for halide single crystals

    Science.gov (United States)

    Yokota, Yuui; Kurosawa, Shunsuke; Shoji, Yasuhiro; Ohashi, Yuji; Kamada, Kei; Yoshikawa, Akira

    2017-03-01

    We developed novel growth methods for halide scintillator single crystals with hygroscopic nature, Halide micro-pulling-down [H-μ-PD] method and Halide Vertical Bridgman [H-VB] method. The H-μ-PD method with a removable chamber system can grow a single crystal of halide scintillator material with hygroscopicity at faster growth rate than the conventional methods. On the other hand, the H-VB method can grow a large bulk single crystal of halide scintillator without a quartz ampule. CeCl3, LaBr3, Ce:LaBr3 and Eu:SrI2 fiber single crystals could be grown by the H-μ-PD method and Eu:SrI2 bulk single crystals of 1 and 1.5 inch in diameter could be grown by the H-VB method. The grown fiber and bulk single crystals showed comparable scintillation properties to the previous reports using the conventional methods.

  6. Large-volume protein crystal growth for neutron macromolecular crystallography.

    Science.gov (United States)

    Ng, Joseph D; Baird, James K; Coates, Leighton; Garcia-Ruiz, Juan M; Hodge, Teresa A; Huang, Sijay

    2015-04-01

    Neutron macromolecular crystallography (NMC) is the prevailing method for the accurate determination of the positions of H atoms in macromolecules. As neutron sources are becoming more available to general users, finding means to optimize the growth of protein crystals to sizes suitable for NMC is extremely important. Historically, much has been learned about growing crystals for X-ray diffraction. However, owing to new-generation synchrotron X-ray facilities and sensitive detectors, protein crystal sizes as small as in the nano-range have become adequate for structure determination, lessening the necessity to grow large crystals. Here, some of the approaches, techniques and considerations for the growth of crystals to significant dimensions that are now relevant to NMC are revisited. These include experimental strategies utilizing solubility diagrams, ripening effects, classical crystallization techniques, microgravity and theoretical considerations.

  7. Crystal growth methods dedicated to low solubility actinide oxalates

    Energy Technology Data Exchange (ETDEWEB)

    Tamain, C., E-mail: christelle.tamain@cea.fr [CEA, Nuclear Energy Division, Marcoule, RadioChemistry & Processes Department, F-30207 Bagnols sur Cèze (France); Arab-Chapelet, B. [CEA, Nuclear Energy Division, Marcoule, RadioChemistry & Processes Department, F-30207 Bagnols sur Cèze (France); Rivenet, M. [University Lille Nord de France, Unité de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, ENSCL-USTL, B.P. 90108, F-59652 Villeneuve d’Ascq Cedex (France); Grandjean, S. [CEA, Nuclear Energy Division, Marcoule, RadioChemistry & Processes Department, F-30207 Bagnols sur Cèze (France); Abraham, F. [University Lille Nord de France, Unité de Catalyse et de Chimie du Solide, UCCS UMR CNRS 8181, ENSCL-USTL, B.P. 90108, F-59652 Villeneuve d’Ascq Cedex (France)

    2016-04-15

    Two novel crystal growth syntheses dedicated to low solubility actinide-oxalate systems and adapted to glove box handling are described. These methods based on the use of precursors of either actinide metal or oxalic acid have been optimized on lanthanide systems (analogue of actinides(III)) and then assessed on real actinide systems. They allow the synthesis of several actinide oxalate single crystals, Am{sub 2}(C{sub 2}O{sub 4}){sub 3}(H{sub 2}O){sub 3}·xH{sub 2}O, Th(C{sub 2}O{sub 4}){sub 2}·6H{sub 2}O, M{sub 2+x}[Pu{sup IV}{sub 2−x}Pu{sup III}{sub x}(C{sub 2}O{sub 4}){sub 5}]·nH{sub 2}O and M{sub 1−x}[Pu{sup III}{sub 1−x}Pu{sup IV}{sub x}(C{sub 2}O{sub 4}){sub 2}·H{sub 2}O]·nH{sub 2}O. It is the first time that these well-known compounds are formed by crystal growth methods, thus enabling direct structural studies on transuranic element systems and acquisition of basic data beyond deductions from isomorphic (or not) lanthanide compounds. Characterizations by X-ray diffraction, UV–visible solid spectroscopy, demonstrate the potentialities of these two crystal growth methods to obtain oxalate compounds. - Graphical abstract: Two new single crystal growth methods dedicated to actinide oxalate compounds. - Highlights: • Use of diester as oxalate precursor for crystal growth of actinide oxalates. • Use of actinide oxide as precursor for crystal growth of actinide oxalates. • Crystal growth of Pu(III) and Am(III) oxalates. • Crystal growth of mixed Pu(III)/Pu(IV) oxalates.

  8. Development of advanced Czochralski growth process to produce low cost 150 kg silicon ingots from a single crucible for technology readiness. [crystal growth

    Science.gov (United States)

    Lane, R. L.

    1981-01-01

    Six growth runs used the Kayex-Hameo Automatic Games Logic (AGILE) computer based system for growth from larger melts in the Mod CG2000. The implementation of the melt pyrometer sensor allowed for dip temperature monitoring and usage by the operator/AGILE system. Use of AGILE during recharge operations was successfully evaluated. The tendency of crystals to lose cylindrical shape (spiraling) continued to be a problem. The hygrometer was added to the Furnace Gas Analysis System and used on several growth runs. The gas chromatograph, including the integrator, was also used for more accurate carbon monoxide concentration measurements. Efforts continued for completing the automation of the total Gas Analysis System. An economic analysis, based on revised achievable straight growth rate, is presented.

  9. Development of Auto-Seeding System Using Image Processing Technology in the Sapphire Crystal Growth Process via the Kyropoulos Method

    Directory of Open Access Journals (Sweden)

    Churl Min Kim

    2017-04-01

    Full Text Available The Kyropoulos (Ky and Czochralski (Cz methods of crystal growth are used for large-diameter single crystals. The seeding process in these methods must induce initial crystallization by initiating contact between the seed crystals and the surface of the melted material. In the Ky and Cz methods, the seeding process lays the foundation for ingot growth during the entire growth process. When any defect occurs in this process, it is likely to spread to the entire ingot. In this paper, a vision system was constructed for auto seeding and for observing the surface of the melt in the Ky method. An algorithm was developed to detect the time when the internal convection of the melt is stabilized by observing the shape of the spoke pattern on the melt material surface. Then, the vision system and algorithm were applied to the growth furnace, and the possibility of process automation was examined for sapphire growth. To confirm that the convection of the melt was stabilized, the position of the island (i.e., the center of a spoke pattern was detected using the vision system and image processing. When the observed coordinates for the center of the island were compared with the coordinates detected from the image processing algorithm, there was an average error of 1.87 mm (based on an image with 1024 × 768 pixels.

  10. Needle-shaped and platelet growth of borax crystals

    International Nuclear Information System (INIS)

    Takoo, R.K.; Patel, B.R.; Joshi, M.S.

    1983-01-01

    Needle-shaped and platelet growth of borax crystals from solutions is reported. Results of microtopographical studies on both the varieties are discussed. It is suggested that a slow rate of evaporation favours needle growth and a faster rate is conducive to the growth of platelets. (author)

  11. A Cannibalistic Approach to Grand Canonical Crystal Growth.

    Science.gov (United States)

    Karmakar, Tarak; Piaggi, Pablo M; Perego, Claudio; Parrinello, Michele

    2018-04-04

    Canonical molecular dynamics simulations of crystal growth from solution suffer from severe finite-size effects. As the crystal grows, the solute molecules are drawn from the solution to the crystal, leading to a continuous drop in the solution concentration. This is in contrast to experiments in which the crystal grows at an approximately constant supersaturation of a bulk solution. Recently, Perego et al. [ J. Chem. Phys. 2015, 142, 144113] showed that in a periodic setup in which the crystal is represented as a slab, the concentration in the vicinity of the two surfaces can be kept constant while the molecules are drawn from a part of the solution that acts as a molecular reservoir. This method is quite effective in studying crystallization under controlled supersaturation conditions. However, once the reservoir is depleted, the constant supersaturation conditions cannot be maintained. We propose a variant of this method to tackle this depletion problem by simultaneously dissolving one side of the crystal while letting the other side grow. A continuous supply of particles to the solution due to the crystal dissolution maintains a steady solution concentration and avoids reservoir depletion. In this way, a constant supersaturation condition can be maintained for as long as necessary. We have applied this method to study the growth and dissolution of urea crystal from water solution under constant supersaturation and undersaturation conditions, respectively. The computed growth and dissolution rates are in good agreement with those obtained in previous studies.

  12. Nucleation and structural growth of cluster crystals

    International Nuclear Information System (INIS)

    Leitold, Christian; Dellago, Christoph

    2016-01-01

    We study the nucleation of crystalline cluster phases in the generalized exponential model with exponent n = 4. Due to the finite value of this pair potential for zero separation, at high densities the system forms cluster crystals with multiply occupied lattice sites. Here, we investigate the microscopic mechanisms that lead to the formation of cluster crystals from a supercooled liquid in the low-temperature region of the phase diagram. Using molecular dynamics and umbrella sampling, we calculate the free energy as a function of the size of the largest crystalline nucleus in the system, and compare our results with predictions from classical nucleation theory. Employing bond-order parameters based on a Voronoi tessellation to distinguish different crystal structures, we analyze the average composition of crystalline nuclei. We find that even for conditions where a multiply occupied fcc crystal is the thermodynamically stable phase, the nucleation into bcc cluster crystals is strongly preferred. Furthermore, we study the particle mobility in the supercooled liquid and in the cluster crystal. In the cluster crystal, the motion of individual particles is captured by a simple reaction-diffusion model introduced previously to model the kinetics of hydrogen bonds.

  13. Growth of lead molybdate crystals by vertical Bridgman method

    Indian Academy of Sciences (India)

    Unknown

    In this paper, we present what is to our knowledge the first report on the vertical Bridgman growth of PMO crystals, which is demonstrated to be an advantageous process for ..... ratio. Owing to the advantages mentioned above, the pre- sent Bridgman process is promising for mass production of PMO crystals with lower cost.

  14. Single crystal growth of europium and ytterbium based intermetallic ...

    Indian Academy of Sciences (India)

    Abstract. This article covers the use of indium as a potential metal solvent for the crystal growth of europium and ytterbium-based intermetallic compounds. A brief view about the advantage of metal flux technique and the use of indium as reactive and non-reactive flux are outlined. Large single crystals of EuGe2, EuCoGe3.

  15. Theory of the intermediate stage of crystal growth with applications to insulin crystallization

    Science.gov (United States)

    Barlow, D. A.

    2017-07-01

    A theory for the intermediate stage of crystal growth, where two defining equations one for population continuity and another for mass-balance, is used to study the kinetics of the supersaturation decay, the homogeneous nucleation rate, the linear growth rate and the final distribution of crystal sizes for the crystallization of bovine and porcine insulin from solution. The cited experimental reports suggest that the crystal linear growth rate is directly proportional to the square of the insulin concentration in solution for bovine insulin and to the cube of concentration for porcine. In a previous work, it was shown that the above mentioned system could be solved for the case where the growth rate is directly proportional to the normalized supersaturation. Here a more general solution is presented valid for cases where the growth rate is directly proportional to the normalized supersaturation raised to the power of any positive integer. The resulting expressions for the time dependent normalized supersaturation and crystal size distribution are compared with experimental reports for insulin crystallization. An approximation for the maximum crystal size at the end of the intermediate stage is derived. The results suggest that the largest crystal size in the distribution at the end of the intermediate stage is maximized when nucleation is restricted to be only homogeneous. Further, the largest size in the final distribution depends only weakly upon the initial supersaturation.

  16. (PCG) Protein Crystal Growth HIV Reverse Transcriptase

    Science.gov (United States)

    1992-01-01

    HIV Reverse Transcriptase crystals grown during the USML-1 (STS-50) mission using Commercial Refrigerator/Incubator Module (CR/IM) at 4 degrees C and the Vapor Diffusion Apparatus (VDA). Reverse transcriptase is an enzyme responsible for copying the nucleic acid genome of the AIDS virus from RNA to DNA. Studies indicated that the space-grown crystals were larger and better ordered (beyond 4 angstroms) than were comparable Earth-grown crystals. Principal Investigators were Charles Bugg and Larry DeLucas.

  17. Direction-specific interactions control crystal growth by oriented attachment

    DEFF Research Database (Denmark)

    Li, Dongsheng; Nielsen, Michael H; Lee, Jonathan R.I.

    2012-01-01

    The oriented attachment of molecular clusters and nanoparticles in solution is now recognized as an important mechanism of crystal growth in many materials, yet the alignment process and attachment mechanism have not been established. We performed high-resolution transmission electron microscopy...... initiated at the contact point. Interface elimination proceeds at a rate consistent with the curvature dependence of the Gibbs free energy. Measured translational and rotational accelerations show that strong, highly direction-specific interactions drive crystal growth via oriented attachment....

  18. Definition study for temperature control in advanced protein crystal growth

    Science.gov (United States)

    Nyce, Thomas A.; Rosenberger, Franz; Sowers, Jennifer W.; Monaco, Lisa A.

    1990-01-01

    Some of the technical requirements for an expedient application of temperature control to advanced protein crystal growth activities are defined. Lysozome was used to study the effects of temperature ramping and temperature gradients for nucleation/dissolution and consecutive growth of sizable crystals and, to determine a prototype temperature program. The solubility study was conducted using equine serum albumin (ESA) which is an extremely stable, clinically important protein due to its capability to bind and transport many different small ions and molecules.

  19. Silicon crystal growth using a liquid-feeding Czochralski method

    Science.gov (United States)

    Shiraishi, Yutaka; Kurosaka, Shoei; Imai, Masato

    1996-09-01

    Silicon single crystals with uniformity along the growth direction were grown using a new continuous Czochralski (CCZ) method. Polycrystalline silicon rods used as charge materials are melted by carbon heaters over a crucible without contact between the raw material and other substances. Using this method, silicon crystals with diameters as large as 6 or 8 inch and good uniformity along the growth direction were grown.

  20. Controlled growth of filamentary crystals and fabrication of single-crystal whisker probes

    International Nuclear Information System (INIS)

    Givargizov, E. I.

    2006-01-01

    The growth of filamentary crystals (whiskers) on a single-crystal substrate through the vapour-liquid-solid mechanism is described. The possibility of fabricating oriented systems of whiskers on the basis of this mechanism of crystal growth is noted. A phenomenon that is important for nanotechnology is noted: the existence of a critical diameter of whiskers, below which they are not formed. The phenomenon of radial periodic instability, which is characteristic of nanowhiskers, is described and the ways of its elimination are shown. The possibility of transforming whiskers into single-crystal tips and the growth of crystalline diamond particles at their apices are noted as important for practice. Possible applications of systems of whiskers and tips are described briefly. Particular attention is paid to the latest direction in whisker technology-fabrication of single-crystal whisker probes for atomic force microscopy

  1. Single crystal growth of 67%BiFeO 3 -33%BaTiO 3 solution by the floating zone method

    Energy Technology Data Exchange (ETDEWEB)

    Rong, Y.; Zheng, H.; Krogstad, M. J.; Mitchell, J. F.; Phelan, D.

    2018-01-01

    The growth conditions and the resultant grain morphologies and phase purities from floating-zone growth of 67%BiFeO3-33%BaTiO3 (BF-33BT) single crystals are reported. We find two formidable challenges for the growth. First, a low-melting point constituent leads to a pre-melt zone in the feed-rod that adversely affects growth stability. Second, constitutional super-cooling (CSC), which was found to lead to dendritic and columnar features in the grain morphology, necessitates slow traveling rates during growth. Both challenges were addressed by modifications to the floating-zone furnace that steepened the temperature gradient at the melt-solid interfaces. Slow growth was also required to counter the effects of CSC. Single crystals with typical dimensions of hundreds of microns have been obtained which possess high quality and are suitable for detailed structural studies.

  2. Nucleation and growth of the Naica giant gypsum crystals.

    Science.gov (United States)

    Otálora, Fermín; García-Ruiz, JuanMa

    2014-04-07

    The Cave of Giant Crystals in the Naica mine (Mexico) is one of the most amazing displays of mineral beauty ever created in nature. In addition to the colossal crystals of gypsum, which in some cases exceed eleven meters in length and one meter in thickness, the scenery fashioned by the crystalline beams that thrust through the darkness of the cave from floor to ceiling with a luster like moonlight is a unique example of harmony based on crystal symmetry. We review the crystallogenesis of this remarkable and challenging phenomenon of mineralization near equilibrium that can be used to teach the basics of nucleation and crystal growth.

  3. Molecular tagging velocimetry characterization of rapid KDP crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Maynes, D.

    2000-03-01

    Measurements of the tangential and axial velocities near the prism faces of a rotating mock crystal mounted on a rotating platform are presented. These measurements were made using molecular tagging velocimetry and are significant to the rapid growth of KDP crystals because they provide a description of the flow field and the evolution of the relative tangential and axial velocities near the prism faces and in the bulk flow region. These data represent the first measurements of fluid velocities around rotating crystal geometries, and thus provide a benchmark for future computer simulations of the crystal growth process at higher Re than previously obtainable. The measurements provide a temporal and spatial description of the evolving velocity field in the vicinity of a rotating crystal. Rotational conditions and locations on the prism faces where low shear rates are likely to occur, based on the measurements presented, are discussed qualitatively.

  4. Advanced crystal growth techniques for thallium bromide semiconductor radiation detectors

    Science.gov (United States)

    Datta, Amlan; Becla, Piotr; Guguschev, Christo; Motakef, Shariar

    2018-02-01

    Thallium Bromide (TlBr) is a promising room-temperature radiation detector candidate with excellent charge transport properties. Currently, Travelling Molten Zone (TMZ) technique is widely used for growth of semiconductor-grade TlBr crystals. However, there are several challenges associated with this type of crystal growth process including lower yield, high thermal stress, and low crystal uniformity. To overcome these shortcomings of the current technique, several different crystal growth techniques have been implemented in this study. These include: Vertical Bridgman (VB), Physical Vapor Transport (PVT), Edge-defined Film-fed Growth (EFG), and Czochralski Growth (Cz). Techniques based on melt pulling (EFG and Cz) were demonstrated for the first time for semiconductor grade TlBr material. The viability of each process along with the associated challenges for TlBr growth has been discussed. The purity of the TlBr crystals along with its crystalline and electronic properties were analyzed and correlated with the growth techniques. Uncorrected 662 keV energy resolutions around 2% were obtained from 5 mm x 5 mm x 10 mm TlBr devices with virtual Frisch-grid configuration.

  5. Crystal growth and scintillation properties of Lu substituted CeBr.sub.3./sub. single crystals

    Czech Academy of Sciences Publication Activity Database

    Ito, T.; Yokota, Y.; Kurosawa, S.; Král, Robert; Kamada, K.; Pejchal, Jan; Ohashi, Y.; Yoshikawa, A.

    2016-01-01

    Roč. 452, Oct (2016), s. 65-68 ISSN 0022-0248. [American Conference on Crystal Growth and Epitaxy /20./ (ACCGE) / 17th Biennial Workshop on Organometallic Vapor Phase Epitaxy (OMVPE) / 2nd 2D Electronic Materials Symposium. Big Sky, MT, 02.08.2015-07.08.2015] Institutional support: RVO:68378271 Keywords : radiation * halides * scintillator materials * crystal growth Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.751, year: 2016

  6. Crystal-face growth rate: role of the neighbouring concentration

    International Nuclear Information System (INIS)

    Itti, R.

    1967-01-01

    A study has been made of the phenomena occurring in the neighbourhood of a growing crystal-face, with the help of several methods based on interferometric observation. If the system is considered at a given moment, it is possible to express the growth rate of the crystal in two ways: 1) using the origin of the solute contributing to the growth, by application of Fick's law modified in certain cases by a correction factor involving the absolute value of the concentration near the crystal face. 2) directly, using the supersaturation in the crystal-face neighbourhood. On the other hand, if an attempt is made to take into account the changes in growth rate with time, it is seen that this rate is not dependent on diffusion phenomena, but that the convection currents in the solution play an important role. (author) [fr

  7. Compatibility waves drive crystal growth on patterned substrates

    International Nuclear Information System (INIS)

    Neuhaus, T; Schmiedeberg, M; Löwen, H

    2013-01-01

    We explore the crystallization in a colloidal monolayer on a structured template starting from a few-particle nucleus. The competition between the substrate structure and that of the growing crystal induces a new crystal growth scenario. Unlike with the crystal growth in the bulk where a well-defined and connected crystal–fluid interface grows into the fluid, we identify a mechanism where a ‘compatibility wave’ of the prescribed nucleus with the underlying substrate structure dictates the growth direction and efficiency. The growth process is strongly anisotropic and proceeds via transient island formation in front of an initial solid–fluid interface. We demonstrate the validity of this compatibility wave concept for a large class of substrate structures including a square lattice and a quasicrystalline pattern. Dynamical density functional theory that provides a microscopic approach to the crystallization process is employed for colloidal hard spheres. Our predictions can be verified in experiments on confined colloids and also bear consequences for molecular crystal growth on structured substrates. (paper)

  8. Crystallization of lysozyme from lysozyme - ovalbumin mixtures: Separation potential and crystal growth kinetics

    Science.gov (United States)

    Maosoongnern, Somchai; Flood, Chalongsri; Flood, Adrian E.; Ulrich, Joachim

    2017-07-01

    Lysozyme was successfully separated from mixtures of lysozyme and ovalbumin by crystallization. The purity of the lysozyme product is more than 98%, the remaining activity is greater than 97%, and the yields of the crystal products were greater than 80%. The experimental conditions used were varied to study the effect of the operating parameters on the growth kinetics of lysozyme crystal and the separation ability of the process. The growth rates of lysozyme are second order with respect to the relative supersaturation. Therefore the growth kinetics of the crystallization process is controlled by the surface integration mechanism. The calculated growth rate constants were 5.4×10-6 cm/h and 2.5×10-6 cm/h for the crystallization process at 20 °C and 10 °C, respectively. There is no significant effect of the ovalbumin impurity up to the concentration of 67.5% ovalbumin (based on total protein) on the growth kinetics of lysozyme. Changing the NaCl concentration from 4% to 3% had no effect on the growth kinetics of lysozyme, although this does change the solubility and therefore the yield. The calculated activation energy was 53.08 kJ/mol which supports the hypothesis that the crystallization process is controlled by the surface integration mechanism.

  9. Synthesis, crystal growth and characterization of nonlinear optical organic crystal: p-Toluidinium p-toluenesulphonate

    International Nuclear Information System (INIS)

    Vijayakumar, P.; Anandha Babu, G.; Ramasamy, P.

    2012-01-01

    Graphical abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. p-TTS single crystal belongs to negative birefringence crystal. Second harmonic conversion efficiency of p-TTS has been found to be 1.3 times higher than that of KDP. Multiple shot surface laser damage threshold is determined to be 0.30 GW/cm 2 at 1064 nm laser radiation. Highlights: ► It deals with the synthesis, growth and characterization of p-TTS an organic NLO crystal. ► Wide optical transparency window between 280 nm and 1100 nm. ► Negative birefringence crystal and dispersion of birefringence is negligibly small. ► Thermal study reveals that the grown crystal is stable up to 210 °C. ► Multiple shot surface laser damage threshold is 0.30 GW/cm 2 at 1064 nm laser radiation. -- Abstract: p-Toluidinium p-toluenesulphonate (p-TTS) an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that p-TTS crystallizes in monoclinic crystal system. The structural perfection of the grown p-TTS single crystal has been analyzed by high-resolution X-ray diffraction rocking curve measurements. Fourier transform infrared spectral studies have been performed to identify the functional groups. The optical transmittance window and the lower cutoff wavelength of the grown crystals have been identified by UV–vis–IR studies. Birefringence of p-TTS crystal has been studied using channel spectrum measurement. The laser damage threshold value was measured using Nd:YAG laser. The second harmonic conversion efficiency of p-TTS has been determined using Kurtz powder technique. Thermo gravimetric and differential thermal analyses were used to study its thermal properties

  10. Modelling of transport phenomena and defects in crystal growth ...

    Indian Academy of Sciences (India)

    A brief review of single crystal growth techniques and the associated problems is presented. Emphasis is placed on models for various transport and defect phenomena involoved in the growth process with the ultimate aim of integrating them into a comprehensive numerical model. The sources of dislocation nucleation in ...

  11. Growth features of ammonium hydrogen d-tartrate single crystals

    Indian Academy of Sciences (India)

    Unknown

    Most of the tartrate compounds are insoluble in water and decompose before melting. Hence, single crystals of such type cannot be grown either by slow evaporation or by melt technique, but can be grown easily by gel method. Gel method is an alternative method to solution growth with controlled diffusion and the growth ...

  12. Silicon Crystal Growth by the Electromagnetic Czochralski (EMCZ) Method

    Science.gov (United States)

    Watanabe, Masahito; Eguchi, Minoru; Hibiya, Taketoshi

    1999-01-01

    A new method for growing silicon crystals by using electromagnetic force to rotate the melt without crucible rotation has been developed. We call it electromagnetic Czochralski (EMCZ) growth. An electromagnetic force in the azimuthal direction is generated in the melt by the interaction between an electric current (I) through the melt in the radial direction and a vertical magnetic field (B). The rotation rate (ωm) of the silicon melt is continuously changed from 0 to over 105 rpm under I = 0 to 8 A and B = 0 to 0.1 T. Thirty-mm-diameter silicon single crystals free of dislocations could be grown under two conditions: I = 2.0 A and B = 0.05 T (ωm = 105 rpm); and I =0.2 A and B = 0.1 T (ωm = 15 rpm). The oxygen concentration in the crystals was 8 ×1017 atoms/cm3 for the high rotation rate and 1×1017 atoms/cm3 for the low rotation rate. The oxygen-concentration distributions in the radial direction in both crystals were more homogeneous than those in the crystals grown by conventional CZ and/or MCZ growth. This new crystal-growth method can be easily adopted for growing large-diameter silicon crystals.

  13. Patterned solid state growth of barium titanate crystals

    Science.gov (United States)

    Ugorek, Michael Stephen

    An understanding of microstructure evolution in ceramic materials, including single crystal development and abnormal/enhanced grain growth should enable more controlled final ceramic element structures. In this study, two different approaches were used to control single crystal development in a patterned array. These two methods are: (1) patterned solid state growth in BaTiO 3 ceramics, and (2) metal-mediated single crystal growth in BaTiO 3. With the patterned solid state growth technique, optical photolithography was used to pattern dopants as well as [001] and [110] BaTiO3 single crystal template arrays with a 1000 microm line pattern array with 1000 microm spacings. These patterns were subsequently used to control the matrix grain growth evolution and single crystal development in BaTiO3. It was shown that the growth kinetics can be controlled by a small initial grain size, atmosphere conditions, and the introduction of a dopant at selective areas/interfaces. By using a PO2 of 1x10-5 atm during high temperature heat treatment, the matrix coarsening has been limited (to roughly 2 times the initial grain size), while retaining single crystal boundary motion up to 0.5 mm during growth for dwell times up to 9 h at 1300°C. The longitudinal and lateral growth rates were optimized at 10--15 microm/h at 1300°C in a PO2 of 1x10 -5 atm for single crystal growth with limited matrix coarsening. Using these conditions, a patterned microstructure in BaTiO3 was obtained. With the metal-mediated single crystal growth technique, a novel approach for fabricating 2-2 single crystal/polymer composites with a kerf ceramic) composites were prepared. The piezoelectric and dielectric properties of the composites of the two compositions were measured. The d33 and d31 of the composites were similar to the polycrystalline ceramic of the same composition.

  14. Growth of Ti or Fe doped lithium niobate single crystals

    International Nuclear Information System (INIS)

    Lee, J.H.; Kim, J.N.; Ro, J.H.; Kim, J.W.; Jeen, G.S.; Kim, Y.C.; Lee, H.S.

    1982-01-01

    This paper reprots a study of the growth of Ti or Fe doped LiNbO 3 single crystals by Czochralski method and its physical properties. On the basis of this study we have developed a growth procedure that produces a high yield of twin-free boules. The quality is better for crystals that are lightly doped with Ti than for those of high concentrations. However there are no significant quality differences among the crystals with concentrations of less than 0.5wt% of Fe. The crystals are characterized by optical absorption and magnetic susceptibility. Undoped crystals show the magnetic susceptibility of -10x10 -6 cgs, which is diamagnetic. The crystals with 0.01wt% and 0.5wt% of ferromagnetic susceptibilities of 2.6x1a -6 cgs, and 80x10 -6 cgs, respectively. Therefore, Fe-doped crystals are paramagnetic. Very small changes of magnetic susceptibilities have been observed in the Ti-doped crystals. (Author)

  15. Monte Carlo simulation of continuous-space crystal growth

    International Nuclear Information System (INIS)

    Dodson, B.W.; Taylor, P.A.

    1986-01-01

    We describe a method, based on Monte Carlo techniques, of simulating the atomic growth of crystals without the discrete lattice space assumed by conventional Monte Carlo growth simulations. Since no lattice space is assumed, problems involving epitaxial growth, heteroepitaxy, phonon-driven mechanisms, surface reconstruction, and many other phenomena incompatible with the lattice-space approximation can be studied. Also, use of the Monte Carlo method circumvents to some extent the extreme limitations on simulated timescale inherent in crystal-growth techniques which might be proposed using molecular dynamics. The implementation of the new method is illustrated by studying the growth of strained-layer superlattice (SLS) interfaces in two-dimensional Lennard-Jones atomic systems. Despite the extreme simplicity of such systems, the qualitative features of SLS growth seen here are similar to those observed experimentally in real semiconductor systems

  16. Crystal Growth of Ternary Compound Semiconductors in Low Gravity Environment

    Science.gov (United States)

    Su, Ching-Hua

    2014-01-01

    A low gravity material experiment will be performed in the Material Science Research Rack (MSRR) on International Space Station (ISS). There are two sections of the flight experiment: (I) crystal growth of ZnSe and related ternary compounds, such as ZnSeS and ZnSeTe, by physical vapor transport (PVT) and (II) melt growth of CdZnTe by directional solidification. The main objective of the project is to determine the relative contributions of gravity-driven fluid flows to the compositional distribution, incorporation of impurities and defects, and deviation from stoichiometry observed in the grown crystals as results of buoyancy-driven convection and growth interface fluctuations caused by irregular fluid-flows on Earth. The investigation consists of extensive ground-based experimental and theoretical research efforts and concurrent flight experimentation. This talk will focus on the ground-based studies on the PVT crystal growth of ZnSe and related ternary compounds. The objectives of the ground-based studies are (1) obtain the experimental data and conduct the analyses required to define the optimum growth parameters for the flight experiments, (2) perfect various characterization techniques to establish the standard procedure for material characterization, (3) quantitatively establish the characteristics of the crystals grown on Earth as a basis for subsequent comparative evaluations of the crystals grown in a low-gravity environment and (4) develop theoretical and analytical methods required for such evaluations. ZnSe and related ternary compounds have been grown by vapor transport technique with real time in-situ non-invasive monitoring techniques. The grown crystals have been characterized extensively by various techniques to correlate the grown crystal properties with the growth conditions.

  17. Convective-diffusive transport in protein crystal growth

    Science.gov (United States)

    Lin, H.; Rosenberger, F.; Alexander, J. I. D.; Nadarajah, A.

    1995-05-01

    Particular interest in the role of convection in protein crystallization has arisen since some protein single crystals of improved structural quality have been obtained under reduced gravity conditions. We have numerically modeled the time-dependent diffusive-convective transport in an isothermal protein crystal growth system at standard and zero gravity (1 g and 0 g). In the 2D model used, a rectangular crystal of fixed dimensions 400 μm × 600 μm is positioned at the bottom of a 1 mm high and 6 mm wide growth cell. The aqueous solution contains protein and precipitant. For the dependence of the crystal growth rate on interfacial supersaturation, experimental data for lysozyme are used. The repartitioning of water and precipitant at the growing interface is based on experimental segregation data for lysozyme: NaCl, and on complete rejection for a fictitious system in which lysozyme and precipitant have the same diffusivity. The results show that even in the small cell employed, protein concentration nonuniformities and gravity-driven solutal convection can be significant. The calculated convection velocities are of the same order of magnitude as those found in earlier experiments. As expected, convective transport enhances the growth rates. However, even when diffusion dominates mass transport, i.e. at 0 g, lysozyme crystal growth remains kinetically limited. Irrespective of the diffusivity of the precipitant, due to the low growth rates, the precipitant distribution in the solution remains rather uniform even at 0 g, unless strong coupling between precipitant and protein fluxes is assumed. The salt distribution in the crystal is predicted to be non-uniform at both 1 g and 0 g, as a consequence of protein depletion in the solution.

  18. Fluid Physics and Macromolecular Crystal Growth in Microgravity

    Science.gov (United States)

    Helliwell, John R.; Snell, Edward H.; Chayen, Naomi E.; Judge, Russell A.; Boggon, Titus J.; Pusey, M. L.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    The first protein crystallization experiment in microgravity was launched in April, 1981 and used Germany's Technologische Experimente unter Schwerelosigkeit (TEXUS 3) sounding rocket. The protein P-galactosidase (molecular weight 465Kda) was chosen as the sample with a liquid-liquid diffusion growth method. A sliding device brought the protein, buffer and salt solution into contact when microgravity was reached. The sounding rocket gave six minutes of microgravity time with a cine camera and schlieren optics used to monitor the experiment, a single growth cell. In microgravity a strictly laminar diffusion process was observed in contrast to the turbulent convection seen on the ground. Several single crystals, approx 100micron in length, were formed in the flight which were of inferior but of comparable visual quality to those grown on the ground over several days. A second experiment using the same protocol but with solutions cooled to -8C (kept liquid with glycerol antifreeze) again showed laminar diffusion. The science of macromolecular structural crystallography involves crystallization of the macromolecule followed by use of the crystal for X-ray diffraction experiments to determine the three dimensional structure of the macromolecule. Neutron protein crystallography is employed for elucidation of H/D exchange and for improved definition of the bound solvent (D20). The structural information enables an understanding of how the molecule functions with important potential for rational drug design, improved efficiency of industrial enzymes and agricultural chemical development. The removal of turbulent convection and sedimentation in microgravity, and the assumption that higher quality crystals will be produced, has given rise to the growing number of crystallization experiments now flown. Many experiments can be flown in a small volume with simple, largely automated, equipment - an ideal combination for a microgravity experiment. The term "protein crystal growth

  19. High-quality single crystals for neutron experiments

    Indian Academy of Sciences (India)

    Abstract. To make headway on any problem in physics, high-quality single crystals are required. In this talk, special emphasis will be placed on the crystal growth of various oxides (superconductors and magnetic materials), borides and carbides using the image furnaces at Warwick. The floating zone method of crystal ...

  20. Crystal growth and physical properties of Ferro-pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Aswartham, Saicharan

    2012-11-08

    The thesis work presented here emphasizes important aspects of crystal growth and the influence of chemical substitution in Fe-As superconductors. High temperature solution growth technique is one of most powerful and widely used technique to grow single crystals of various materials. The biggest advantage of high temperature solution growth technique is the, possibility of growing single crystals from both congruently and incongruently melting materials. Solution growth technique has the potential to control high vapour pressures, given the fact that, in Fe-based superconductors elements with high vapour pressure like As, K, Li and Na have to be handled during the crystal growth procedure. In this scenario high temperature solution growth is the best suitable growth technique to synthesize sizable homogeneous single crystals. Using self-flux high temperature solution growth technique, large centimeter-sized high quality single crystals of BaFe{sub 2}As{sub 2} were grown. This pristine compound BaFe{sub 2}As{sub 2} undergoes structural and magnetic transition at T{sub S/N} = 137 K. By suppressing this magnetic transition and stabilizing tetragonal phase with chemical substitution, like Co-doping and Na-doping, bulk superconductivity is achieved. Superconducting transitions of as high as T{sub c} = 34 K with Na substitution and T{sub c} = 25 K with Co-doping were obtained. A combined electronic phase diagram has been achieved for both electron doping with Co and hole doping with Na in BaFe{sub 2}As{sub 2}. Single crystals of LiFe{sub 1-x}Co{sub x}As with x = 0, 0.025, 0.05 and 0.075 were grown by a self-flux high temperature solution growth technique. The charge doping in LiFeAs is achieved with the Co-doping in Fe atoms. The superconducting properties investigated by means of temperature dependent magnetization and resistivity revealed that superconductivity is shifted to lower temperatures and with higher amount of charge carriers superconductivity is killed

  1. Bridgman growth of bismuth tellurite crystals

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The photorefractive crystal, Bi2TeO5, was grown by the modified Bridgman method for the first time. High purity Bi2O3 and TeO2 were used as starting materials and were mixed thoroughly with molar ratio of Bi2O3/TeO2 = 1 : 1. Platinum crucible was fabricated with a seed well of 10 mm in diameter and several.

  2. Bridgman growth of bismuth tellurite crystals

    Indian Academy of Sciences (India)

    The photorefractive crystal, Bi2TeO5, was grown by the modified Bridgman method for the first time. High purity Bi2O3 and TeO2 were used as starting materials and were mixed thoroughly with molar ratio of Bi2O3/TeO2 = 1 : 1. Platinum crucible was fabricated with a seed well of 10 mm in diameter and several folds were ...

  3. Hydrothermal crystal growth of oxides for optical applications

    Science.gov (United States)

    McMillen, Colin David

    2007-12-01

    The manipulation of light has proven to be an integral part of today's technology-based society. In particular, there is great interest in obtaining coherent radiation in all regions of the optical spectrum to advance technology in military, medical, industrial, scientific and consumer fields. Exploring new crystal growth techniques as well as the growth of new optical materials is critical in the advancement of solid state optics. Surprisingly, the academic world devotes little attention to the growth of large crystals. This shortcoming has left gaps in the optical spectrum inaccessible by solid state devices. This dissertation explores the hydrothermal crystal growth of materials that could fill two such gaps. The first gap exists in the deep-UV region, particularly below 200 nm. Some materials such as LiB3O5 and beta-BaB2O4 can generate coherent light at wavelengths as low as 205 nm. The growth of these materials was explored to investigate the feasibility of the hydrothermal method as a new technique for growing these crystals. Particular attention was paid to the descriptive chemistry surrounding these systems, and several novel structures were elucidated. The study was also extended to the growth of materials that could be used for the generation of coherent light as low as 155 nm. Novel synthetic schemes for Sr2Be2B2O7 and KBe2BO 3F2 were developed and the growth of large crystals was explored. An extensive study of the structures, properties and crystal growth of related compounds, RbBe2BO3F2 and CsBe2BO 3F2, was also undertaken. Optimization of a number of parameters within this family of compounds led to the hydrothermal growth of large, high quality single crystal at rates suitable for large-scale growth. The second gap in technology is in the area of high average power solid state lasers emitting in the 1 mum and eye-safe (>1.5 mum) regions. A hydrothermal technique was developed to grow high quality crystals of Sc 2O3 and Sc2O3 doped with suitable

  4. Defect reduction in seeded aluminum nitride crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Bondokov, Robert T.; Morgan, Kenneth E.; Schowalter, Leo J.; Stack, Glen A.

    2017-04-18

    Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density.ltoreq.100 cm.sup.-2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.

  5. Defect reduction in seeded aluminum nitride crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Bondokov, Robert T.; Morgan, Kenneth E.; Schowalter, Leo J.; Slack, Glen A.

    2017-06-06

    Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density .ltoreq.100 cm.sup.-2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.

  6. Defect reduction in seeded aluminum nitride crystal growth

    Science.gov (United States)

    Bondokov, Robert T.; Schowalter, Leo J.; Morgan, Kenneth; Slack, Glen A; Rao, Shailaja P.; Gibb, Shawn Robert

    2017-09-26

    Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density.ltoreq.100 cm.sup.-2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.

  7. Crystal growth and comparison of vibrational and thermal properties

    Indian Academy of Sciences (India)

    with the spectrum of urea thiourea mercury chloride (UTHC) (red) isolated by grow- ing a crystal using urea (u), thiourea (tu) and HgCl2, in 1 : 1 : 1 mole ratio showing that both are one and the same. is no mention of growth of any doped crystals other than the UTHC and UTHS. Fur- ther, it is unfortunate that the exact nature ...

  8. The effect of growth rate, diameter and impurity concentration on structure in Czochralski silicon crystal growth

    Science.gov (United States)

    Digges, T. G., Jr.; Shima, R.

    1980-01-01

    It is demonstrated that maximum growth rates of up to 80% of the theoretical limit can be attained in Czochralski-grown silicon crystals while maintaining single crystal structure. Attaining the other 20% increase is dependent on design changes in the grower, to reduce the temperature gradient in the liquid while increasing the gradient in the solid. The conclusions of Hopkins et al. (1977) on the effect of diameter on the breakdown of structure at fast growth rates are substantiated. Copper was utilized as the test impurity. At large diameters (greater than 7.5 cm), concentrations of greater than 1 ppm copper were attained in the solid (45,000 ppm in the liquid) without breakdown at maximum growth speeds. For smaller diameter crystals, the sensitivity of impurities is much more apparent. For solar cell applications, impurities will limit cell performance before they cause crystal breakdown for fast growth rates of large diameter crystals.

  9. Iron single crystal growth from a lithium-rich melt

    Science.gov (United States)

    Fix, M.; Schumann, H.; Jantz, S. G.; Breitner, F. A.; Leineweber, A.; Jesche, A.

    2018-03-01

    α -Fe single crystals of rhombic dodecahedral habit were grown from a Li84N12Fe∼3 melt. Crystals of several millimeter along a side form at temperatures around T ≈ 800 ° C. Upon further cooling the growth competes with the formation of Fe-doped Li3N. The b.c.c. structure and good sample quality of α -Fe single crystals were confirmed by X-ray and electron diffraction as well as magnetization measurements and chemical analysis. A nitrogen concentration of 90 ppm was detected by means of carrier gas hot extraction. Scanning electron microscopy did not reveal any sign of iron nitride precipitates.

  10. Ultra-large single crystals by abnormal grain growth.

    Science.gov (United States)

    Kusama, Tomoe; Omori, Toshihiro; Saito, Takashi; Kise, Sumio; Tanaka, Toyonobu; Araki, Yoshikazu; Kainuma, Ryosuke

    2017-08-25

    Producing a single crystal is expensive because of low mass productivity. Therefore, many metallic materials are being used in polycrystalline form, even though material properties are superior in a single crystal. Here we show that an extraordinarily large Cu-Al-Mn single crystal can be obtained by abnormal grain growth (AGG) induced by simple heat treatment with high mass productivity. In AGG, the sub-boundary energy introduced by cyclic heat treatment (CHT) is dominant in the driving pressure, and the grain boundary migration rate is accelerated by repeating the low-temperature CHT due to the increase of the sub-boundary energy. With such treatment, fabrication of single crystal bars 70 cm in length is achieved. This result ensures that the range of applications of shape memory alloys will spread beyond small-sized devices to large-scale components and may enable new applications of single crystals in other metallic and ceramics materials having similar microstructural features.Growing large single crystals cheaply and reliably for structural applications remains challenging. Here, the authors combine accelerated abnormal grain growth and cyclic heat treatments to grow a superelastic shape memory alloy single crystal to 70 cm.

  11. The mechanism of growth of quartz crystals into fused silica

    Science.gov (United States)

    Fratello, V. J.; Hays, J. F.; Spaepen, F.; Turnbull, D.

    1980-01-01

    It is proposed that the growth of quartz crystals into fused silica is effected by a mechanism involving the breaking of an Si-O bond and its association with an OH group, followed by cooperative motion of the nonbridging oxygen and the hydroxyl group which results in the crystallization of a row of several molecules along a crystalline-amorphous interfacial ledge. This mechanism explains, at least qualitatively, all the results of the earlier experimental study of the dependence of quartz crystal growth upon applied pressure: large negative activation volume; single activation enthalpy below Si-O bond energy; growth velocity constant in time, proportional to the hydroxyl and chlorine content, decreasing with increasing degree of reduction, and enhanced by nonhydrostatic stresses; lower pre-exponential for the synthetic than for the natural silica.

  12. Crystal-growth Underground Breeding Extra-sensitive Detectors

    Science.gov (United States)

    Mei, Dongming

    2012-02-01

    CUBED (Center for Ultra-Low Background Experiments at DUSEL) collaborators from USD, SDSMT, SDSU, Sanford Lab, and Lawrence Berkeley National Laboratory are working on the development of techniques to manufacture crystals with unprecedented purity levels in an underground environment that may be used by experiments proposed for DUSEL. The collaboration continues to make significant progress toward its goal of producing high purity germanium crystals. High quality crystals are being pulled on a weekly basis at the temporary surface growth facility located on the USD campus. The characterization of the grown crystals demonstrates that the impurity levels are nearly in the range of the needed impurity level for detector-grade crystals. Currently, the crystals are being grown in high-purity hydrogen atmosphere. With an increase in purity due to the zone refining, the group expects to grow high-purity crystals by the end of 2011. The one third of the grown crystals will be manufactured to be detectors; the remaining will be fabricated in to wafers that have large applications in electro and optical devices as well as solar panels. This would allow the research to be connected to market and create more than 30 jobs and multi millions revenues in a few years.

  13. Crystal growth of large crystals of YBa2(Cu1-xFex)3Oy

    International Nuclear Information System (INIS)

    Das, B.N.; Osofsky, M.S.; Koon, K.C.

    1991-01-01

    Large crystals of YBa 2 (Cu 1-x Fe x ) 3 O y were grown from a solution of BaO:CuO mixture. The proper amount of Y 2 O 3 , BaCO 3 , CuO and Fe 2 O 3 were well mixed and placed in either Al 2 O 3 or ZrO 2 crucibles. For crystal growth, the crucibles were heated up to 1040 degrees C in air, held there for a specific length of time and cooled slowly in the liquid state from 980 degrees C. This paper discusses the nature of the crystals produced, the Fe content in the crystal as related to the growth condition, the superconducting and the magnetic properties

  14. Growth and Characterization of Tl2S Single Crystals

    Science.gov (United States)

    Gamal, G. A.; Zied, M. Abou; Gerges, M. K.; Galal, E. M.

    2003-09-01

    Single crystals of the Tl2S compound were grown for the first time in our laboratory by a new crystal growth technique based on a modification of the traveling heater method technique (THM). This growth was performed in our laboratory. Electrical conductivity, Hall effect and thermoelectric power (TEP) measurements were carried out in the temperature range (200-575 K). Throughout these measurements, various physical parameters such as effective mass of charge carriers, carrier mobility, diffusion length, diffusion coefficient, and the relaxation time for both majority and minority carriers were found. In conjunction with electrical conductivity and charge carrier concentration, thermoelectric power is discussed.

  15. Studying of crystal growth and overall crystallization of naproxen from binary mixtures.

    Science.gov (United States)

    Kaminska, E; Madejczyk, O; Tarnacka, M; Jurkiewicz, K; Kaminski, K; Paluch, M

    2017-04-01

    Broadband dielectric spectroscopy (BDS) and differential scanning calorimetry (DSC) were applied to investigate the molecular dynamics and phase transitions in binary mixtures composed of naproxen (NAP) and acetylated saccharides: maltose (acMAL) and sucrose (acSUC). Moreover, the application of BDS method and optical microscopy enabled us to study both crystallization kinetics and crystal growth of naproxen from the solid dispersions with the highest content of modified carbohydrates (1:5wt ratio). It was found that the activation barriers of crystallization estimated from dielectric measurements are completely different for both studied herein mixtures. Much higher E a (=205kJ/mol) was obtained for NAP-acMAL solid dispersion. It is probably due to simultaneous crystallization of both components of the mixture. On the other hand, lower value of E a in the case of NAP-acSUC solid dispersion (81kJ/mol) indicated, that naproxen is the only crystallizing compound. This hypothesis was confirmed by X-ray diffraction studies. We also suggested that specific intermolecular dipole-dipole interactions between active substance and excipient may be an alternative explanation for the difference between activation barrier obtained for NAP-acMAL and NAP-acSUC binary mixtures. Furthermore, optical measurements showed that the activation energy for crystal growth of naproxen increases in binary mixtures. They also revealed that both excipients: acMAL and acSUC move the temperature of the maximum of crystal growth towards lower temperatures. Interestingly, this maximum occurs for nearly the same structural relaxation time, which is a good approximation of viscosity, for all samples. Finally, it was also noticed that although naproxen crystallizes to the same polymorphic form in both systems, there are some differences in morphology of obtained crystals. Thus, the observed behavior may have a significant impact on the bioavailability and dissolution rate of API produced in that way

  16. Growth of large detector crystals. CRADA final report

    Energy Technology Data Exchange (ETDEWEB)

    Boatner, L.A. [Oak Ridge National Lab., TN (United States); Samuelson, S. [Deltronic Crystal Industries, Dover, NJ (United States)

    1997-06-18

    In the course of a collaborative research effort between L.A. Boatner of Oak Ridge National Laboratory and Prof. Alex Lempicki of the Department of Chemistry of Boston University, a new highly efficient and very fast scintillator for the detection of gamma-rays was discovered. This new scintillator consists of a single crystal of lutetium orthophosphate (LuPO{sub 4}) to which a small percentage of trivalent cerium is added as an activator ion. The new lutetium orthophosphate-cerium scintillator was found to be superior in performance to bismuth germanium oxide--a material that is currently widely used as a gamma-ray detector in a variety of medical, scientific, and technical applications. Single crystals of LuPO{sub 4} and related rare-earth orthophosphates had been grown for a number of years in the ORNL Solid State Division prior to the discovery of the efficient gamma-ray-scintillation response of LuPO{sub 4}:Ce. The high-temperature-solvent (flux-growth) method used for the growth of these crystals was capable of producing crystals in sizes that were adequate for research purposes but that were inadequate for commercial-scale production and widespread application. The CRADA between ORNL and Deltronic Crystal Industries of Dover, NJ was undertaken for the purpose of investigating alternate approaches, such as top-seeded-solution growth, to the growth of LuPO{sub 4}:Ce scintillator crystals in sizes significantly larger than those obtainable through the application of standard flux-growth methods and, therefore, suitable for commercial sales and applications.

  17. Growth and characterisation of lead iodide single crystals

    International Nuclear Information System (INIS)

    Tonn, Justus

    2012-01-01

    The work in hand deals with the growth and characterisation of lead iodide (PbI 2 ) single crystals. PbI 2 is regarded as a promising candidate for low-noise X- and gamma ray detection at room temperature. Its benefits if compared to conventional materials like HgI 2 , CdTe, Si, or GaAs lie in a band gap energy of 2.32 eV, an excellent ability to absorb radiation, and a high electrical resistivity. For an application of PbI 2 as detector material the growth and characterisation of crystals with high chemical and structural quality is extremely challenging. In light of this, the effectiveness of zone purification of the PbI 2 used for crystal growth was confirmed by spectroscopic analysis. Furthermore, technological aspects during processing of purified PbI 2 were investigated. With the help of thermal analysis, a correlation was found between the degree of exposing the source material to oxygen from the air and the structural quality of the resulting crystals. A hydrogen treatment was applied to PbI 2 as an effective method for the removal of oxidic pollutions, which resulted in a significant reduction of structural defects like polytypic growth and stress-induced cracking. The growth of PbI 2 single crystals was, among others, carried out by the Bridgman-Stockbarger method. In this context, much effort was put on the investigation of influences resulting from the design and preparation of ampoules. For the first time, crystal growth of PbI 2 was also carried out by the Czochralski method. If compared to the Bridgman-Stockbarger method, the Czochralski technique allowed a significantly faster growth of nearly crack-free crystals with a reproducible predetermination of crystallographic orientation. By an optimised sample preparation of PbI 2 , surface orientations perpendicular to the usually cleaved (0001) plane were realised. It is now possible to determine the material properties along directions which were so far not accessible. Thus, for example, the ratio of

  18. Effects of growth conditions on thermal profiles during Czochralski silicon crystal growth

    Science.gov (United States)

    Choe, Kwang Su; Stefani, Jerry A.; Dettling, Theodore B.; Tien, John K.; Wallace, John P.

    1991-01-01

    An eddy current testing method was used to continuously monitor crystal growth process and investigate the effects of growth conditions on thermal profiles during Czochralski silicon crystal growth. The experimental concept was to monitor the intrinsic electrical conductivities of the growing crystal and deduce temperature values from them. In terms of the experiments, the effects of changes in growth parameters, which include the crystal and crucible rotation rates, crucible position, and pull rate, and hot-zone geometries were investigated. The results show that the crystal thermal profile could shift significantly as a function of crystal length if the closed-loop control fails to maintain a constant thermal condition. As a direct evidence to the effects of the melt flow on heat transfer processes, a thermal gradient minimum was observed when the crystal/crucible rotation combination was 20/-10 rpm cw. The thermal gradients in the crystal near the growth interface were reduced most by decreasing the pull rate or by reducing the radiant heat loss to the environment; a nearly constant axial thermal gradient was achieved when either the pull rate was decreased by half, the height of the exposed crucible wall was doubled, or a radiation shield was placed around the crystal. Under these conditions, the average axial thermal gradient along the surface of the crystal was about 4-5°C/mm. When compared to theoretical results found in literature, the axial profiles correlated well with the results of the models which included radiant interactions. However, the radial gradients estimated from three-frequency data were much higher than what were predicted by known theoretical models. This discrepancy seems to indicate that optical phenomenon within the crystal is significant and should be included in theoretical modeling.

  19. The Growth of Protein Crystals Using McDUCK

    Science.gov (United States)

    Ewing, Felicia; Wilson, Lori; Nadarajah, Arunan; Pusey, Marc

    1998-01-01

    Most of the current microgravity crystal growth hardware is optimized to produce crystals within the limited time available on orbit. This often results in the actual nucleation and growth process being rushed or the system not coming to equilibrium within the limited time available. Longer duration hardware exists, but one cannot readily pick out crystals grown early versus those which nucleated and grew more slowly. We have devised a long duration apparatus, the Multi-chamber Dialysis Unit for Crystallization Kinetics, or McDUCK. This apparatus-is a series of protein chambers, stacked upon a precipitant reservoir chamber. All chambers are separated by a dialysis membrane, which serves to pass small molecules while retaining the protein. The volume of the Precipitant chamber is equal to the sum of the volumes of the protein chamber. In operation, the appropriate chambers are filled with precipitant solution or protein solution, and the McDUCK is placed standing upright, with the precipitant chamber on the bottom. The precipitant diffuses upwards over time, with the time to reach equilibration a function of the diffusivity of the precipitant and the overall length of the diffusion pathway. Typical equilibration times are approximately 2-4 months, and one can readily separate rapid from slow nucleation and growth crystals. An advantage on Earth is that the vertical precipitant concentration gradient dominates that of the solute, thus dampening out solute density gradient driven convective flows. However, large Earth-grown crystals have so far tended to be more two dimensional. Preliminary X-ray diffraction analysis of lysozyme crystals grown in McDUCK have indicated that the best, and largest, come from the middle chambers, suggesting that there is an optimal growth rate. Further, the improvements in diffraction resolution have been better signal to noise ratios in the low resolution data, not an increase in resolution overall. Due to the persistently large crystals

  20. Growth, spectral and thermal studies of ibuprofen crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ramukutty, S.; Ramachandran, E. [Department of Physics, Thiruvalluvar College, Papanasam (India)

    2012-01-15

    RS -Ibuprofen was crystallized for the first time in silica gel under suitable pH conditions by reduction of solubility method. The grown crystals were characterized by single crystal X-ray diffraction and density measurement. The functional groups present in the crystal were identified using Fourier transform infrared spectroscopy. Optical bandgap energy of ibuprofen was estimated as 3.19(3) eV from UV-Vis spectrum. Thermogravimetric analysis revealed that ibuprofen is thermally stable upto 102.9 C and the initial loss of mass was due to evaporation only. Morphological study showed that the growth is prominent along b-axis and the prominent face is {l_brace}100{r_brace}. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Growth and scintillation properties of gadolinium and yttrium orthovanadate crystals

    International Nuclear Information System (INIS)

    Voloshina, O.V.; Baumer, V.N.; Bondar, V.G.; Kurtsev, D.A.; Gorbacheva, T.E.; Zenya, I.M.; Zhukov, A.V.; Sidletskiy, O.Ts.

    2012-01-01

    Aiming to explore the possibility of using the undoped rare-earth orthovanadates as scintillation materials, we developed the procedure for growth of gadolinium (GdVO 4 ) and yttrium (YVO 4 ) orthovanadate single crystals by Czochralski method, and determined the optimal conditions of their after-growth annealing. Optical, luminescent, and scintillation properties of YVO 4 and GdVO 4 were discussed versus known literature data. Scintillation characteristics of GdVO 4 were determined for the first time.

  2. Growth morphology of zinc tris (thiourea) sulphate crystals

    Indian Academy of Sciences (India)

    The growth morphology of crystals of zinc tris(thiourea) sulphate (ZTS) is investigated experimentally, and computed using the Hartman–Perdok approach. Attachment energies of the observed habit faces are calculated for determining their relative morphological importance. A computer code is developed for carrying out ...

  3. Growth morphology of zinc tris(thiourea) sulphate crystals

    Indian Academy of Sciences (India)

    Abstract. The growth morphology of crystals of zinc tris(thiourea) sulphate (ZTS) is investigated experimentally, and computed using the Hartman–Perdok approach. Attachment energies of the observed habit faces are calculated for determining their relative morphological importance. A com- puter code is developed for ...

  4. Control of interface shape during high melting sesquioxide crystal growth by HEM technique

    Science.gov (United States)

    Hu, Kaiwei; Zheng, Lili; Zhang, Hui

    2018-02-01

    During crystal growth in heat exchanger method (HEM) system, the shape of the growth interface changes with the proceeding of the growth process, which limits the crystal size and reduces the quality of the crystal. In this paper, a modified HEM system is proposed to control the interface shape for growth of sesquioxide crystals. Numerical simulation is performed to predict heat transfer, melt flow and interface shape during growth of high melting sesquioxide crystals by the heat exchanger method. The results show that a flat or slightly convex interface shape is beneficial to reduce the solute pileup in front of the melt/crystal interface and decrease the radial temperature gradient inside the crystal during growth of sesquioxide crystals. The interface shape can be controlled by adjusting the gap size d and lower resistance heater power during growth. The growth rate and the melt/crystal interface position can be obtained by two measured temperatures.

  5. Selective crystal growth of polymorphs and crystal-to-crystal thermal phase transition of non-peripherally alkyl-substituted phthalocyanine and tetrabenzotriazaporphyrin

    Science.gov (United States)

    Ohmori, Masashi; Nakano, Chika; Fujii, Akihiko; Shimizu, Yo; Ozaki, Masanori

    2017-06-01

    Selective crystal growth of polymorphs and crystal-to-crystal thermal phase transition of non-peripherally alkyl-substituted macrocycle molecules, such as octapentylphthalocyanine (C5PcH2), octahexylphthalocyanine (C6PcH2), and octahexyltetrabenzotriazaporphyrin (C6TBTAPH2) have been investigated. Two types of single crystals, called α-type and β-type, were separately grown by controlling the recrystallization conditions, and the crystal structures were determined by single-crystal X-ray structure analysis. The irreversible crystal-to-crystal thermal phase transition from α-type to β-type were observed by the differential scanning calorimetry and temperature-controlled X-ray structure analysis. The selective crystal growth of the α-type or β-type and the irreversible crystal-to-crystal thermal phase transition have been discussed by taking the alkyl-substituent distribution into consideration.

  6. The 1993 annual conference of the Israeli Association for Crystal Growth. Program and abstracts

    International Nuclear Information System (INIS)

    1993-11-01

    Papers presented in oral and poster sessions of one day conference, organized by Israeli Association for Crystal Growth, are compiled in this document. Main topics covered in this document can be classified as: (i) Fundamental and numerical analysis of crystal growth. (ii) Techniques of crystal growth and structural analysis. (iii) Thin film growth and characterization

  7. Lysozyme crystal growth, as observed by small angle X-ray scattering, proceeds without crystallization intermediates

    International Nuclear Information System (INIS)

    Finet, S.; Bonnete, F.; Frouin, J.; Provost, K.; Tardieu, A.

    1998-01-01

    A combination of small angle X-ray scattering and gel techniques was used to follow the kinetics of protein crystal growth as a function of time. Hen egg white lysozyme, at different protein concentrations, was used as a model system. A new sample holder was designed, in which supersaturation is induced in the presence of salt by decreasing the temperature. It had been shown previously that a decrease in temperature and/or an increase in crystallizing agent induces an increase in the attractive interactions present in the lysozyme solutions, the lysozyme remaining monomeric. In the present paper we show that similar behaviour is observed in NaCl when agarose gels are used. During crystal growth, special attention was paid to determine whether oligomers were formed as the protein in solution was incorporated in the newly formed crystals. From these first series of experiments, we did not find any indication of oligomer formation between monomer in solution and crystal. The results obtained are in agreement with the hypothesis that lysozyme crystals in NaCl grow by addition of monomeric particles. (orig.)

  8. Crystal growth and property characterization for PIN–PMN–PT ternary piezoelectric crystals

    Directory of Open Access Journals (Sweden)

    Jian Tian

    2014-01-01

    Full Text Available Binary piezoelectric crystal Pb(Mg1/3Nb2/3O3–PbTiO3 (PMN–PT has excellent dielectric and piezoelectric properties, which has led to the commercialization for medical ultrasound imaging. Recently, there is a growing demand for piezoelectric crystals with improved thermal and electrical properties. Ternary piezoelectric crystals Pb(In1/2Nb1/2O3–Pb(Mg1/3Nb2/3O3–PbTiO3 (PIN–PMN–PT have increased depoling temperature and coercive field than binary PMN–PT. To better understand the ternary crystal system and improve crystal properties, we systematically investigated crystal growth of PIN–PMN–PT with modified Bridgman method. Like PMN–PT, PIN–PMN–PT crystals have excellent piezoelectric properties (e.g., k33 ~ 0.87–0.92, d33 ~ 1000–2200 pm/V. Higher PIN content leads to ~40°C increase in depoling temperature and more than doubling of coercive field(~7.0 kV/cm. Such improvements are advantageous for applications where high temperature and/or high-drive are needed.

  9. Crystal growth of Mg2Si for IR-detector

    Science.gov (United States)

    Tokairin, Toshio; Ikeda, Junya; Udono, Haruhiko

    2017-06-01

    Semiconducting Mg2Si is known as a thermoelectric material and recently attracts increasing attention as a Si-based, low-cost and environmental friendly material for an infrared (IR) sensor. With the aim of producing cost-effective Mg2Si single crystal substrates for the IR sensor, we have investigated single crystal growth of Mg2Si using the vertical Bridgman (VB) and micro-pulling-down (μ-PD) methods in open-system. Since the evaporation of Mg was not suppressed during the μ-PD, the composition of the Mg2Si single crystal grown by this method was not stoichiometric. On the other hand, single crystalline Mg2Si was produced by the VB method using the Si-treated inner carbon seat and BN-coated carbon crucible. The Mg2Si crystals with a diameter of 30 mm were grown at a growth rate of 0.5 mm/min and a temperature gradient of 5 °C/cm. The electron density and mobility of the crystal so obtained were 1.8×1017 cm-3 and 283 cm2V-1s-1 at 300 K, respectively. The high electron density was due to contamination from the impurities presented in the crucible.

  10. Crystal growth and magnetic property of YFeO3 crystal

    Indian Academy of Sciences (India)

    Experimental. The starting materials for the preparation of feed rods for the floating zone crystal growth were Y2O3 (99·99%) and. Fe2O3 (99·99%) powders. Stoichiometric amounts of the raw materials of absolute ethanol for 24 h were milled in the present study. After drying and screening, the mixture was calcined at 1100.

  11. Control of crystal growth in water purification by directional freeze crystallization

    Science.gov (United States)

    Conlon, William M. (Inventor)

    1996-01-01

    A Directional Freeze Crystallization system employs an indirect contact heat exchanger to freeze a fraction of liquid to be purified. The unfrozen fraction is drained away and the purified frozen fraction is melted. The heat exchanger must be designed in accordance with a Growth Habit Index to achieve efficient separation of contaminants. If gases are dissolved in the liquid, the system must be pressurized.

  12. Thin film modeling of crystal dissolution and growth in confinement

    Science.gov (United States)

    Gagliardi, Luca; Pierre-Louis, Olivier

    2018-01-01

    We present a continuum model describing dissolution and growth of a crystal contact confined against a substrate. Diffusion and hydrodynamics in the liquid film separating the crystal and the substrate are modeled within the lubrication approximation. The model also accounts for the disjoining pressure and surface tension. Within this framework, we obtain evolution equations which govern the nonequilibrium dynamics of the crystal interface. Based on this model, we explore the problem of dissolution under an external load, known as pressure solution. We find that in steady state, diverging (power-law) crystal-surface repulsions lead to flat contacts with a monotonic increase of the dissolution rate as a function of the load. Forces induced by viscous dissipation then surpass those due to disjoining pressure at large enough loads. In contrast, finite repulsions (exponential) lead to sharp pointy contacts with a dissolution rate independent of the load and the liquid viscosity. Ultimately, in steady state, the crystal never touches the substrate when pressed against it. This result is independent from the nature of the crystal-surface interaction due to the combined effects of viscosity and surface tension.

  13. Crystal Splitting in the Growth of Bi2S3

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jing; Alivisatos, A. Paul

    2006-06-15

    Novel Bi{sub 2}S{sub 3} nanostructures with a sheaf-like morphology are obtained via reaction of bismuth acetate-oleic acid complex with elemental sulfur in 1-octadecence. We propose these structures form by the splitting crystal growth mechanism, which is known to account for the morphology some mineral crystals assume in nature. By controlling the synthetic parameters, different forms of splitting, analogous to observed in minerals, are obtained in our case of Bi{sub 2}S{sub 3}. These new and complex Bi{sub 2}S{sub 3} nanostructures are characterized by TEM, SEM, XRD and ED.

  14. Nanoparticle-mediated nonclassical crystal growth of sodium fluorosilicate nanowires and nanoplates

    Directory of Open Access Journals (Sweden)

    Hongxia Li

    2011-12-01

    Full Text Available We observed nonclassical crystal growth of the sodium fluorosilicate nanowires, nanoplates, and hierarchical structures through self-assembly and aggregation of primary intermediate nanoparticles. Unlike traditional ion-by-ion crystallization, the primary nanoparticles formed first and their subsequent self-assembly, fusion, and crystallization generated various final crystals. These findings offer direct evidences for the aggregation-based crystallization mechanism.

  15. Crystal growth and characterization of calcium metaborate scintillators

    Science.gov (United States)

    Fujimoto, Y.; Yanagida, T.; Kawaguchi, N.; Fukuda, K.; Totsuka, D.; Watanabe, K.; Yamazaki, A.; Chani, V.; Nikl, M.; Yoshikawa, A.

    2013-03-01

    Calcium metaborate CaB2O4 single crystals were grown by the Czochralski (CZ) method with the radio-frequency (RF) heating system. In these crystals, a plane cleavage was observed along the growth direction. The crystals had an 80% transparency, and no absorption bands were detected in the 190-900 nm wavelength range. The 241Am 5.5 MeV α-ray-excited radioluminescence spectrum of CaB2O4 demonstrated a broad intrinsic luminescence peak at 300-400 nm, which originated from the lattice defects or an exciton-based emission. According to the pulse height spectrum, when irradiated by neutrons from a 252Cf source, the scintillation light yielded approximately 3200 photons per neutron (ph/n).

  16. Numerical simulation of the oxygen concentration distribution in silicon melt for different crystal lengths during Czochralski growth with a transverse magnetic field

    Science.gov (United States)

    Chen, Jyh-Chen; Chiang, Pei-Yi; Nguyen, Thi Hoai Thu; Hu, Chieh; Chen, Chun-Hung; Liu, Chien-Cheng

    2016-10-01

    A three-dimensional simulation model is used to study the oxygen concentration distribution in silicon crystal during the Czochralski growth process under a transverse uniform magnetic field. The flow, temperature, and oxygen concentration distributions inside the furnace are calculated for different crystal lengths. There is significant variation in the flow structure in the melt with the growth length. The results show that in the initial stages, there is a decrease in the oxygen concentration at the crystal-melt interface as the length of the growing crystal increases. As the crystal lengthens further, a minimum value is reached after which the oxygen concentration increases continuously. This trend is consistent with that shown in the experimental results. The variation of the oxygen concentration with the growth length is strongly related to the depth of the melt in the crucible and the flow structure inside the melt. Better uniformity of the axial oxygen concentration can be achieved by proper adjustment of the crucible rotation rate during the growth process.

  17. Crystal growth and anisotropy of high temperature thermoelectric properties of yttrium borosilicide single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Hossain, M. Anwar [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba 305-0044 (Japan); Center for Crystal Science and Technology, University of Yamanashi, Miyamae 7-32, Kofu, Yamanashi 400-8511 (Japan); Tanaka, Isao [Center for Crystal Science and Technology, University of Yamanashi, Miyamae 7-32, Kofu, Yamanashi 400-8511 (Japan); Tanaka, Takaho; Khan, A. Ullah [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba 305-0044 (Japan); Mori, Takao, E-mail: MORI.Takao@nims.go.jp [International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba 305-0044 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba 305-8671 (Japan)

    2016-01-15

    We studied thermoelectric properties of YB{sub 41}Si{sub 1.3} single crystals grown by the floating zone method. The composition of the grown crystal was confirmed by electron probe micro-analysis. We have determined the growth direction for the first time for these borosilicides, and discovered relatively large anisotropy in electrical properties. We measured the electrical resistivity and Seebeck coefficient along [510] (the growth direction) and [052] directions and we found that this crystal exhibits strong electrical anisotropy with a maximum of more than 8 times. An interesting layered structural feature is revealed along [510] with dense boron cluster layers and yttrium layers, with conductivity enhanced along this direction. We obtained 3.6 times higher power factor along [510] compared to that along [052]. Although the ZT of the present system is low, anisotropy in the thermoelectric properties of a boride was reported for the first time, and can be a clue in developing other boride systems also. - Graphical abstract: The growth direction ([510]) was determined for the first time in YB{sub 41}Si{sub 1.3} single crystals and revealed an interesting layered feature of boron clusters and metal atoms, along which the electrical conductivity and thermoelectric power factor was strongly enhanced. - Highlights: • We have grown YB{sub 41}Si{sub 1.3} single crystals by the floating zone method. • Growth direction of [510] determined for first time in REB{sub 41}Si{sub 1.2}. • Electrical resistivity was strongly anisotropic with possible enhancement along metal layers. • The obtained power factor along [510] is 3.6 times higher than that along [052].

  18. Surface-engineered growth of AgIn₅S₈ crystals.

    Science.gov (United States)

    Lai, Chia-Hung; Chiang, Ching-Yeh; Lin, Po-Chang; Yang, Kai-Yu; Hua, Chi Chung; Lee, Tai-Chou

    2013-05-01

    The growth of semiconductor crystals and thin films plays an essential role in industry and academic research. Considering the environmental damage caused by energy consumption during their fabrication, a simpler and cheaper method is desired. In fact, preparing semiconductor materials at lower temperatures using solution chemistry has potential in this research field. We found that solution chemistry, the physical and chemical properties of the substrate surface, and the phase diagram of the multicomponent compound semiconductor have a decisive influence on the crystal structure of the material. In this study, we used self-assembled monolayers (SAMs) to modify the silicon/glass substrate surface and effectively control the density of the functional groups and surface energy of the substrates. We first employed various solutions to grow octadecyltrichlorosilane (OTS), 3-mercaptopropyl-trimethoxysilane (MPS), and mixed OTS-MPS SAMs. The surface energy can be adjusted between 24.9 and 50.8 erg/cm(2). Using metal sulfide precursors in appropriate concentrations, AgIn5S8 crystals can be grown on the modified substrates without any post-thermal treatment. We can easily adjust the nucleation in order to vary the density of AgIn5S8 crystals. Our current process can achieve AgIn5S8 crystals of a maximum of 1 μm in diameter and a minimum crystal density of approximately 0.038/μm(2). One proof-of-concept experiment demonstrated that the material prepared from this low temperature process showed positive photocatalytic activity. This method for growing crystals can be applied to the green fabrication of optoelectronic materials.

  19. Single-crystal metal growth on amorphous insulating substrates.

    Science.gov (United States)

    Zhang, Kai; Pitner, Xue Bai; Yang, Rui; Nix, William D; Plummer, James D; Fan, Jonathan A

    2018-01-23

    Metal structures on insulators are essential components in advanced electronic and nanooptical systems. Their electronic and optical properties are closely tied to their crystal quality, due to the strong dependence of carrier transport and band structure on defects and grain boundaries. Here we report a method for creating patterned single-crystal metal microstructures on amorphous insulating substrates, using liquid phase epitaxy. In this process, the patterned metal microstructures are encapsulated in an insulating crucible, together with a small seed of a differing material. The system is heated to temperatures above the metal melting point, followed by cooling and metal crystallization. During the heating process, the metal and seed form a high-melting-point solid solution, which directs liquid epitaxial metal growth. High yield of single-crystal metal with different sizes is confirmed with electron backscatter diffraction images, after removing the insulating crucible. Unexpectedly, the metal microstructures crystallize with the [Formula: see text] direction normal to the plane of the film. This platform technology will enable the large-scale integration of high-performance plasmonic and electronic nanosystems.

  20. Confined crystallization of organic materials in nanopipettes : tracking the early stages of crystal growth and making seeds for unusual polymorphs

    OpenAIRE

    Maddar, Faduma; Perry, David; Unwin, Patrick R.

    2017-01-01

    Nanopipettes are used as nanoreactors to study the crystallization of bicalutamide, in a nanoscale antisolvent configuration. Potential controlled ion migration is used to mix an aqueous solution and a dimethyl sulfoxide phase containing bicalutamide, inducing crystallization at the nanopore interface, and generating current blockades due to the nucleation and growth of crystal seeds.

  1. Development and melt growth of novel scintillating halide crystals

    Czech Academy of Sciences Publication Activity Database

    Yoshikawa, A.; Yokota, Y.; Shoji, Y.; Král, Robert; Kamada, K.; Kurosawa, S.; Ohashi, Y.; Arakawa, M.; Chani, V.I.; Kochurikhin, V.V.; Yamaji, A.; Medvedev, A.; Nikl, Martin

    2017-01-01

    Roč. 74, Dec (2017), s. 109-119 ISSN 0925- 3467 Institutional support: RVO:68378271 Keywords : scintillator * halide * crystal growth from the melt * Bridgman method * Czochralski method * edge-defined film-fed method * micro-pulling-down method Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.238, year: 2016

  2. Growth of crystalline semiconductor materials on crystal surfaces

    CERN Document Server

    Aleksandrov, L

    2013-01-01

    Written for physicists, chemists, and engineers specialising in crystal and film growth, semiconductor electronics, and various applications of thin films, this book reviews promising scientific and engineering trends in thin films and thin-films materials science. The first part discusses the physical characteristics of the processes occurring during the deposition and growth of films, the principal methods of obtaining semiconductor films and of reparing substrate surfaces on which crystalline films are grown, and the main applications of films. The second part contains data on epitaxial i

  3. In Situ Observation of Antisite Defect Formation during Crystal Growth

    International Nuclear Information System (INIS)

    Kramer, M. J.; Napolitano, R. E.; Mendelev, M. I.

    2010-01-01

    In situ x-ray diffraction (XRD) coupled with molecular dynamics (MD) simulations have been used to quantify antisite defect trapping during crystallization. Rietveld refinement of the XRD data revealed a marked lattice distortion which involves an a axis expansion and a c axis contraction of the stable C11b phase. The observed lattice response is proportional in magnitude to the growth rate, suggesting that the behavior is associated with the kinetic trapping of lattice defects. MD simulations demonstrate that this lattice response is due to incorporation of 1% to 2% antisite defects during growth.

  4. A simple furnace for neutron diffraction studies

    International Nuclear Information System (INIS)

    Bailey, F.P.; Bennett, C.E.G.

    1979-01-01

    A simple yet effective high temperature furnace for heating crystals or powder specimens for neutron diffraction studies on a theta/2theta diffractometer is described. The furnace can maintain samples at temperatures up to 1573 K, in air, with a stability of +- 4 K for periods of many hours. Specimen temperature is uniform within 12 K, or much less with the use of a silica sleeve. (Auth.)

  5. A Proposed Model for Protein Crystal Nucleation and Growth

    Science.gov (United States)

    Pusey, Marc; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    How does one take a molecule, strongly asymmetric in both shape and charge distribution, and assemble it into a crystal? We propose a model for the nucleation and crystal growth process for tetragonal lysozyme, based upon fluorescence, light, neutron, and X-ray scattering data, size exclusion chromatography experiments, dialysis kinetics, AFM, and modeling of growth rate data, from this and other laboratories. The first species formed is postulated to be a 'head to side' dimer. Through repeating associations involving the same intermolecular interactions this grows to a 4(sub 3) helix structure, that in turn serves as the basic unit for nucleation and subsequent crystal growth. High salt attenuates surface charges while promoting hydrophobic interactions. Symmetry facilitates subsequent helix-helix self-association. Assembly stability is enhanced when a four helix structure is obtained, with each bound to two neighbors. Only two unique interactions are required. The first are those for helix formation, where the dominant interaction is the intermolecular bridging anion. The second is the anti-parallel side-by-side helix-helix interaction, guided by alternating pairs of symmetry related salt bridges along each side. At this stage all eight unique positions of the P4(sub3)2(sub 1),2(sub 1) unit cell are filled. The process is one of a) attenuating the most strongly interacting groups, such that b) the molecules begin to self-associate in defined patterns, so that c) symmetry is obtained, which d) propagates as a growing crystal. Simple and conceptually obvious in hindsight, this tells much about what we are empirically doing when we crystallize macromolecules. By adjusting the growth parameters we are empirically balancing the intermolecular interactions, preferentially attenuating the dominant strong (for lysozyme the charged groups) while strengthening the lesser strong (hydrophobic) interactions. In the general case for proteins the lack of a singularly defined

  6. Crystal growth, structure analysis and characterisation of 2 - (1, 3 - dioxoisoindolin - 2 - yl) acetic acid single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sankari, R. Siva, E-mail: sivasankari.sh@act.edu.in [Department of Physics, Agni College of Technology, Thalambur, Chennai-603103 (India); Perumal, Rajesh Narayana [Department of Physics, SSN College of Engineering, Kalavakkam, Chennai-603110 (India)

    2014-04-24

    Single crystal of dielectric material 2 - (1, 3 - dioxoisoindolin - 2 - yl) acetic acid has been grown by slow evaporation solution growth method. The grown crystal was harvested in 25 days. The crystal structure was analyzed by Single crystal X - ray diffraction. UV-vis-NIR analysis was performed to examine the optical property of the grown crystal. The thermal property of the grown crystal was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The dielectric measurements were carried out and the dielectric constant was calculated and plotted at all frequencies.

  7. Magnetic Control in Crystal Growth from a Melt

    Science.gov (United States)

    Huang, Yue

    Control of bulk melt crystal growth techniques is desirable for producing semiconductors with the highest purity and ternary alloys with tunable electrical properties. Because these molten materials are electrically conducting, external magnetic fields are often employed to regulate the flow in the melt. However, complicated by the coupled flow, thermal, electromagnetic and chemical physics, such magnetic control is typically empirical or even an educated guess. Two magnetic flow control mechanisms: flow damping by steady magnetic fields, and flow stirring by alternating magnetic fields, are investigated numerically. Magnetic damping during optically-heated float-zone crystal growth is modeled using a spectral collocation method. The Marangoni convection at the free melt-gas interface is suppressed when exposed to a steady axial magnetic field, measured by the Hartmann number Ha. As a result, detrimental flow instabilities are suppressed, and an almost quiescent region forms in the interior, ideal for single crystal growth. Using normal mode linear stability analyses, dominant flow instabilities are determined in a range applicable to experiments (up to Ha = 300 for Pr = 0.02, and up to Ha = 500 for Pr = 0.001). The hydrodynamic nature of the instability for small Prandtl number Pr liquid bridges is confirmed by energy analyses. Magnetic stirring is modeled for melt crystal growth in an ampule exposed to a transverse rotating magnetic field. Decoupled from the flow field at small magnetic Reynolds number, the electromagnetic field is first solved via finite element analysis. The flow field is then solved using the spectral element method. At low to moderate AC frequencies (up to a few kHz), the electromagnetic body force is dominant in the azimuthal direction, which stirs a steady axisymmetric flow primarily in the azimuthal direction. A weaker secondary flow develops in the meridional plane. However, at high AC frequencies (on the order of 10 kHz and higher), only

  8. Crystal growth and scintillation properties of selected fluoride crystals for VUV scintillators

    Czech Academy of Sciences Publication Activity Database

    Pejchal, Jan; Fukuda, K.; Yamaji, A.; Yokota, Y.; Kurosawa, S.; Král, Robert; Nikl, Martin; Yoshikawa, A.

    2014-01-01

    Roč. 401, Sep (2014), s. 833-838 ISSN 0022-0248. [International Conference on Crystal Growth and Epitaxy /17./. Warsaw, 11.08.2013-16..08.2013] R&D Projects: GA MŠk LH12150 Institutional support: RVO:68378271 Keywords : vacuum-ultra-violet emission * micro-pulling-down method * barium -lutetium fluoride * erbium fluoride Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.698, year: 2014

  9. Acquisition of Single Crystal Growth and Characterization Equipment. Final report

    International Nuclear Information System (INIS)

    Maple, M. Brian; Zocco, Diego A.

    2008-01-01

    Final Report for DOE Grant No. DE-FG02-04ER46178 'Acquisition of Single Crystal Growth and Characterization Equipment'. There is growing concern in the condensed matter community that the need for quality crystal growth and materials preparation laboratories is not being met in the United States. It has been suggested that there are too many researchers performing measurements on too few materials. As a result, many user facilities are not being used optimally. The number of proficient crystal growers is too small. In addition, insufficient attention is being paid to the enterprise of finding new and interesting materials, which is the driving force behind much of condensed matter research and, ultimately, technology. While a detailed assessment of this situation is clearly needed, enough evidence of a problem already exists to compel a general consensus that the situation must be addressed promptly. This final report describes the work carried out during the last four years in our group, in which a state-of-the-art single crystal growth and characterization facility was established for the study of novel oxides and intermetallic compounds of rare earth, actinide and transition metal elements. Research emphasis is on the physics of superconducting (SC), magnetic, heavy fermion (HF), non-Fermi liquid (NFL) and other types of strongly correlated electron phenomena in bulk single crystals. Properties of these materials are being studied as a function of concentration of chemical constituents, temperature, pressure, and magnetic field, which provide information about the electronic, lattice, and magnetic excitations at the root of various strongly correlated electron phenomena. Most importantly, the facility makes possible the investigation of material properties that can only be achieved in high quality bulk single crystals, including magnetic and transport phenomena, studies of the effects of disorder, properties in the clean limit, and spectroscopic and scattering

  10. Acquisition of Single Crystal Growth and Characterization Equipment

    Energy Technology Data Exchange (ETDEWEB)

    Maple, M. Brian; Zocco, Diego A.

    2008-12-09

    Final Report for DOE Grant No. DE-FG02-04ER46178 'Acquisition of Single Crystal Growth and Characterization Equipment'. There is growing concern in the condensed matter community that the need for quality crystal growth and materials preparation laboratories is not being met in the United States. It has been suggested that there are too many researchers performing measurements on too few materials. As a result, many user facilities are not being used optimally. The number of proficient crystal growers is too small. In addition, insufficient attention is being paid to the enterprise of finding new and interesting materials, which is the driving force behind much of condensed matter research and, ultimately, technology. While a detailed assessment of this situation is clearly needed, enough evidence of a problem already exists to compel a general consensus that the situation must be addressed promptly. This final report describes the work carried out during the last four years in our group, in which a state-of-the-art single crystal growth and characterization facility was established for the study of novel oxides and intermetallic compounds of rare earth, actinide and transition metal elements. Research emphasis is on the physics of superconducting (SC), magnetic, heavy fermion (HF), non-Fermi liquid (NFL) and other types of strongly correlated electron phenomena in bulk single crystals. Properties of these materials are being studied as a function of concentration of chemical constituents, temperature, pressure, and magnetic field, which provide information about the electronic, lattice, and magnetic excitations at the root of various strongly correlated electron phenomena. Most importantly, the facility makes possible the investigation of material properties that can only be achieved in high quality bulk single crystals, including magnetic and transport phenomena, studies of the effects of disorder, properties in the clean limit, and spectroscopic and

  11. Controlling Molecular Growth between Fractals and Crystals on Surfaces.

    Science.gov (United States)

    Zhang, Xue; Li, Na; Gu, Gao-Chen; Wang, Hao; Nieckarz, Damian; Szabelski, Paweł; He, Yang; Wang, Yu; Xie, Chao; Shen, Zi-Yong; Lü, Jing-Tao; Tang, Hao; Peng, Lian-Mao; Hou, Shi-Min; Wu, Kai; Wang, Yong-Feng

    2015-12-22

    Recent studies demonstrate that simple functional molecules, which usually form two-dimensional (2D) crystal structures when adsorbed on solid substrates, are also able to self-assemble into ordered openwork fractal aggregates. To direct and control the growth of such fractal supramolecules, it is necessary to explore the conditions under which both fractal and crystalline patterns develop and coexist. In this contribution, we study the coexistence of Sierpiński triangle (ST) fractals and 2D molecular crystals that were formed by 4,4″-dihydroxy-1,1':3',1″-terphenyl molecules on Au(111) in ultrahigh vacuum. Growth competition between the STs and 2D crystals was realized by tuning substrate and molecular surface coverage and changing the functional groups of the molecular building block. Density functional theory calculations and Monte Carlo simulations are used to characterize the process. Both experimental and theoretical results demonstrate the possibility of steering the surface self-assembly to generate fractal and nonfractal structures made up of the same molecular building block.

  12. Morphology of β-BaB2O4 (BBO) in relation to its crystal structure and growth conditions

    International Nuclear Information System (INIS)

    Bolt, R.J.; Bennema, P.

    1993-01-01

    A periodic-bond-chain (PBC) analysis has been made of the structure of β-BaB 2 O 4 (BBO) and related to crystal growth conditions, in order to explain the sometimes tangerine-shaped, sometimes needle-shaped crystals that are observed when BBO is grown experimentally. The periodic bond chains generate eight-connected nets in BBO. The order of morphological importance (MI) of these F faces is determined by comparing the nearest-neighbour interaction ionic bond energies. The results are compared with experimental data. Six faces, sometimes observed parallel to the c axis of BBO, were identified as the hexagonal prism {11 anti 20}. Two other forms are either the trigonal pyramids {01 anti 12} and {01 anti 1 anti 2} or the trigonal pyramids {10 anti 12} and {01 anti 1 anti 2}. {0001} is an important cleavage plane. The tangerine habit is a result of the strong temperature gradient, which is often used when growing BBO. The isotherms of the furnace impose their habit on the growing crystal. (orig.)

  13. Diagenetic Crystal Growth in the Murray Formation, Gale Crater, Mars

    Science.gov (United States)

    Kah, L. C.; Kronyak, R. E.; Ming, D. W.; Grotzinger, J. P.; Schieber, J.; Sumner, D. Y.; Edgett, K. S.

    2015-01-01

    The Pahrump region (Gale Crater, Mars) marks a critical transition between sedimentary environments dominated by alluvial-to-fluvial materials associated with the Gale crater rim, and depositional environments fundamentally linked to the crater's central mound, Mount Sharp. At Pahrump, the Murray formation consists of an approximately 14-meter thick succession dominated by massive to finely laminated mudstone with occasional interbeds of cross-bedded sandstone, and is best interpreted as a dominantly lacustrine environment containing tongues of prograding fluvial material. Murray formation mudstones contain abundant evidence for early diagenetic mineral precipitation and its subsequent removal by later diagenetic processes. Lenticular mineral growth is particularly common within lacustrine mudstone deposits at the Pahrump locality. High-resolution MAHLI images taken by the Curiosity rover permit detailed morphological and spatial analysis of these features. Millimeter-scale lenticular features occur in massive to well-laminated mudstone lithologies and are interpreted as pseudomorphs after calcium sulfate. The distribution and orientation of lenticular features suggests deposition at or near the sediment-water (or sediment-air) interface. Retention of chemical signals similar to host rock suggests that original precipitation was likely poikilotopic, incorporating substantial amounts of the primary matrix. Although poikilotopic crystal growth is common in burial environments, it also occurs during early diagenetic crystal growth within unlithified sediment where high rates of crystal growth are common. Loss of original calcium sulfate mineralogy suggests dissolution by mildly acidic, later-diagenetic fluids. As with lenticular voids observed at Meridiani by the Opportunity Rover, these features indicate that calcium sulfate deposition may have been widespread on early Mars; dissolution of depositional and early diagenetic minerals is a likely source for both calcium

  14. Single Crystals of Organolead Halide Perovskites: Growth, Characterization, and Applications

    KAUST Repository

    Peng, Wei

    2017-04-01

    crystals will be discussed in Chapter 3 and 4. Despite their outstanding charge transport characteristics, organolead halide perovskite single crystals grown by hitherto reported crystallization methods are not suitable for most optoelectronic devices due to their small aspect ratios and free standing growth. As the other major part of work of this dissertation, explorative work on growing organolead halide perovskite monocrystalline films and further their application in solar cells will be discussed in Chapter 5.

  15. The growth of single crystals of Ni-W alloy under conditions of high temperature gradient

    International Nuclear Information System (INIS)

    Azhazha, V.M.; Gorbenko, Yu.V.; Kovtun, G.P.; Ladygin, A.N.; Malykhin, D.G.; Rudycheva, T.Yu.; Sverdlov, V.Ya.; Shcherban', A.P.; Zhemanyuk, P.D.; Klochikhin, V.V.

    2004-01-01

    The structure of single crystals of the NV-4 nickel alloy containing 32-36 wt % W is investigated. The temperature gradient at the crystallization front and the velocity of the crystallization front are the variable parameters of directional crystallization. The degrees of structural perfection of the single crystals grown under different conditions are compared. The crystallization parameters providing growth of single crystals that have high structural perfection and can be successfully used as seeds for the growth of single-crystal blades are determined. Typical defects formed upon directional crystallization of single crystals of the Ni-W (35 wt %) alloy are examined. The studied defects are classified, and the factors responsible for the disturbance of the single-crystal structure are analyzed

  16. Modeling of crystal morphology : growth simulation on facets in arbitrary orientations

    NARCIS (Netherlands)

    Boerrigter, Stephan Xander Mattheus

    2003-01-01

    Many aspects of crystal morphology modeling are studied in this thesis. Most important of all, is the dependence of crystal growth on supersaturation--the driving force for crystallization--which not only influences the crystal morphology, but also polymorphism and nucleation. It is shown that an

  17. Investigation on the bulk growth of α-LiIO 3 single crystals and the ...

    Indian Academy of Sciences (India)

    2017-07-26

    Jul 26, 2017 ... Herein, we investigate to grow bulk size good quality crystals of α-LiIO3 based on the observed problems during its crystallization process. A systematic investigation was carried out to find the effect of pH on solubility, crystal growth, structural, surface and laser damage properties of α-LiIO3 single crystals.

  18. Modeling the effects of the vertical temperature gradient in the furnace in an edge-defined film-fed growth technique

    International Nuclear Information System (INIS)

    Epure, S.; Braescu, L.; Balint, St.

    2006-01-01

    In this paper, the mathematical model for the growth of cylindrical bars described elsewhere is considered. Using MathCAD 11 Enterprise Edition and mathematical tools, the asymptotically stable steady-states (r*, h*) of the nonlinear system of differential equations which governs the evolution of the bar radius r=r(t) and the meniscus height h=h(t), for different values of the pulling rate v, the melt temperature T 0 at the meniscus basis and the vertical temperature gradient k in the furnace, respectively, are found. For a given k, the range of the stable growth regions in the (v, T 0 ) plane (i.e. those couples (v, T 0 ) for which (r*, h*) has physical sense) are determined. The effects of the changes of the vertical temperature gradient k are investigated and it is shown that if v and T 0 are constant, and k increases, then the bar radius r increases and the meniscus height h decreases. Numerical results are given for the silicon bar grown in an edge-defined film-fed growth (E.F.G.) system with a die radius r 0e =20(cmx10 -2 )

  19. Comparative Study of Furnace and Flash Lamp Annealed Silicon Thin Films Grown by Plasma Enhanced Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Maheshwar Shrestha

    2018-03-01

    Full Text Available Low-temperature growth of microcrystalline silicon (mc-Si is attractive for many optoelectronic device applications. This paper reports a detailed comparison of optical properties, microstructure, and morphology of amorphous silicon (a-Si thin films crystallized by furnace annealing and flash lamp annealing (FLA at temperatures below the softening point of glass substrate. The initial a-Si films were grown by plasma enhanced chemical vapor deposition (PECVD. Reflectance measurement indicated characteristic peak in the UV region ~280 nm for the furnace annealed (>550 °C and flash lamp annealed films, which provided evidence of crystallization. The film surface roughness increased with increasing the annealing temperature as well as after the flash lamp annealing. X-ray diffraction (XRD measurement indicated that the as-deposited samples were purely amorphous and after furnace crystallization, the crystallites tended to align in one single direction (202 with uniform size that increased with the annealing temperature. On the other hand, the flash lamp crystalized films had randomly oriented crystallites with different sizes. Raman spectroscopy showed the crystalline volume fraction of 23.5%, 47.3%, and 61.3% for the samples annealed at 550 °C, 650 °C, and with flash lamp, respectively. The flash lamp annealed film was better crystallized with rougher surface compared to furnace annealed ones.

  20. Apparatus for growing HgI.sub.2 crystals

    Science.gov (United States)

    Schieber, Michael M.; Beinglass, Israel; Dishon, Giora

    1978-01-01

    A method and horizontal furnace for vapor phase growth of HgI.sub.2 crystals which utilizes controlled axial and radial airflow to maintain the desired temperature gradients. The ampoule containing the source material is rotated while axial and radial air tubes are moved in opposite directions during crystal growth to maintain a desired distance and associated temperature gradient with respect to the growing crystal, whereby the crystal interface can advance in all directions, i.e., radial and axial according to the crystallographic structure of the crystal. Crystals grown by this method are particularly applicable for use as room-temperature nuclear radiation detectors.

  1. Effect of melt supercooling on growth shape of iron crystals

    International Nuclear Information System (INIS)

    Kostyuchenko, V.P.; Fedorov, O.P.

    1985-01-01

    When investigating solidification of pure iron castings in supercooling interval from 0 to 300 K it is shown that at high ΔT=100-300 K nucleation takes place from one centre. Granular sturucture of a casting is a resutt of secondary processes and is not related to the solidification structure. At ΔT=100-300 K a transition from dendrite to needle mode of growth is detected, which is accompanied by grinding and breaking of structure elements. Comparison with the morphology of crystals of model material-cyclohexanol, is carried out

  2. Inclusion free cadmium zinc tellurium and cadmium tellurium crystals and associated growth method

    Science.gov (United States)

    Bolotnikov, Aleskey E [South Setauket, NY; James, Ralph B [Ridge, NY

    2010-07-20

    The present disclosure provides systems and methods for crystal growth of cadmium zinc tellurium (CZT) and cadmium tellurium (CdTe) crystals with an inverted growth reactor chamber. The inverted growth reactor chamber enables growth of single, large, high purity CZT and CdTe crystals that can be used, for example, in X-ray and gamma detection, substrates for infrared detectors, or the like. The inverted growth reactor chamber enables reductions in the presence of Te inclusions, which are recognized as an important limiting factor in using CZT or CdTe as radiation detectors. The inverted growth reactor chamber can be utilized with existing crystal growth techniques such as the Bridgman crystal growth mechanism and the like. In an exemplary embodiment, the inverted growth reactor chamber is a U-shaped ampoule.

  3. VO{sub 2} (A): Reinvestigation of crystal structure, phase transition and crystal growth mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Rao Popuri, Srinivasa [ICMCB, CNRS, UPR 9048, F-33608 Pessac (France); University of Bordeaux, ICMCB, UPR 9048, F-33608 Pessac (France); National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, Plautius Andronescu Str. No. 1, 300224 Timisoara (Romania); Artemenko, Alla [ICMCB, CNRS, UPR 9048, F-33608 Pessac (France); University of Bordeaux, ICMCB, UPR 9048, F-33608 Pessac (France); Labrugere, Christine [CeCaMA, University of Bordeaux 1, ICMCB, 87 Avenue du Dr. A. Schweitzer, F-33608 Pessac (France); Miclau, Marinela [National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, Plautius Andronescu Str. No. 1, 300224 Timisoara (Romania); Villesuzanne, Antoine [ICMCB, CNRS, UPR 9048, F-33608 Pessac (France); University of Bordeaux, ICMCB, UPR 9048, F-33608 Pessac (France); Pollet, Michaël, E-mail: pollet@icmcb-bordeaux.cnrs.fr [ICMCB, CNRS, UPR 9048, F-33608 Pessac (France); University of Bordeaux, ICMCB, UPR 9048, F-33608 Pessac (France)

    2014-05-01

    Well crystallized VO{sub 2} (A) microrods were grown via a single step hydrothermal reaction in the presence of V{sub 2}O{sub 5} and oxalic acid. With the advantage of high crystalline samples, we propose P4/ncc as an appropriate space group at room temperature. From morphological studies, we found that the oriented attachment and layer by layer growth mechanisms are responsible for the formation of VO{sub 2} (A) micro rods. The structural and electronic transitions in VO{sub 2} (A) are strongly first order in nature, and a marked difference between the structural transition temperatures and electronic transitions temperature was evidenced. The reversible intra- (LTP-A to HTP-A) and irreversible inter- (HTP-A to VO{sub 2} (M1)) structural phase transformations were studied by in-situ powder X-ray diffraction. Attempts to increase the size of the VO{sub 2} (A) microrods are presented and the possible formation steps for the flower-like morphologies of VO{sub 2} (M1) are described. - Graphical abstract: Using a single step and template free hydrothermal synthesis, well crystallized VO{sub 2} (A) microrods were prepared and the P4/ncc space group was assigned to the room temperature crystal structure. Reversible and irreversible phase transitions among different VO{sub 2} polymorphs were identified and their progressive nature was highlighted. Attempts to increase the microrods size, involving layer by layer formation mechanisms, are presented. - Highlights: • Highly crystallized VO{sub 2} (A) microrods were grown via a single step hydrothermal process. • The P4/ncc space group was determined for VO{sub 2} (A) at room temperature. • The electronic structure and progressive nature of the structural phase transition were investigated. • A weak coupling between structural and electronic phase transitions was identified. • Different crystallite morphologies were discussed in relation with growth mechanisms.

  4. On the origin of radiation growth of hcp crystals

    Energy Technology Data Exchange (ETDEWEB)

    Golubov, Stanislav I [ORNL; Barashev, Aleksandr [University of Liverpool; Stoller, Roger E [ORNL

    2012-03-01

    The aim of the present work is to study theoretically the radiation growth (RG) of hcp-type materials with a particular focus on the effect of one-dimensionally (1-D) migrating clusters of self-interstitial atoms (SIAs), which are steadily produced in displacement cascades under neutron or heavy-ion irradiation. A reaction-diffusion model is developed for the description of RG in single hcp-type metallic crystals. The model reproduces all RG stages observed in neutron-irradiated annealed samples of pure Zr and Zr alloys, such as high strain rate at low, strain saturation at intermediate and breakaway growth at relatively high irradiation doses. In addition, it accounts for the striking observations of negative strains in prismatic directions and coexistence of vacancy- and SIA-type prismatic loops. The role of cold work in RG behavior and alignment of the vacancy-type loops along basal planes are revealed and the maximum strain rate is estimated.

  5. Growth and Characteristics of Bulk Single Crystals Grown from Solution on Earth and in Microgravity

    Science.gov (United States)

    Aggarwal, M. D.; Batra, A. K.; Lal, R. B.; Penn, Benjamin G.; Frazier, Donald O.

    2011-01-01

    The growth of crystals has been of interest to physicists and engineers for a long time because of their unique properties. Single crystals are utilized in such diverse applications as pharmaceuticals, computers, infrared detectors, frequency measurements, piezoelectric devices, a variety of high technology devices and sensors. Solution crystal growth is one of the important techniques to grow a variety of crystals when the material decomposes at the melting point and a suitable solvent is available to make a saturated solution at a desired temperature. In this chapter an attempt is made to give some fundamentals of growing crystals from solution including improved designs of various crystallizers. Since the same solution crystal growth technique could not be used in microgravity, authors had proposed a new cooled sting technique to grow crystals in space. Authors? experiences of conducting two space shuttle experiments relating to solution crystal growth are also detailed in this work. The complexity of these solution growth experiments to grow crystals in space are discussed. These happen to be some of the early experiments performed in space, and various lessons learned are described. A brief discussion of protein crystal growth that also shares basic principles of solution growth technique is given along with some flight hardware information for its growth in microgravity.

  6. Growth and evaluation of lanthanoids orthoniobates single crystals processed by a miniature pedestal growth technique

    International Nuclear Information System (INIS)

    Octaviano, E.S.; Reyes Ardila, D.; Andrade, L.H.C.; Siu Li, M.; Andreeta, J.P.

    2004-01-01

    Optimized conditions for the growth of lanthanoids orthoniobates (LnNbO 4 , Ln=lanthanide elements) single crystal minirods by a floating zone technique were investigated. Adequate atmospheres and pulling to feeding speed ratios to grow these materials were determined. Emphasis is given to the study of LaNbO 4 because of their more favorable growth conditions and crystalline quality. This material can be efficiently doped with rare earth elements such as erbium. It grows with high crystallinity and its preferential growth direction is [110]. A preliminary evaluation of optical properties of Er 3+ -doped LaNbO 4 single crystal under the Judd-Ofelt formalism indicates spectral parameters Ω t close and even larger than for Er 3+ ions in YVO 4 . (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Crystal growth, structural and thermal studies of amino acids admixtured L-arginine phosphate monohydrate single crystals

    Science.gov (United States)

    Anandan, P.; Saravanan, T.; Parthipan, G.; Kumar, R. Mohan; Bhagavannarayana, G.; Ravi, G.; Jayavel, R.

    2011-05-01

    To study the improved characteristics of L-arginine phosphate monohydrate (LAP) crystals, amino acids mixed LAP crystals have been grown by slow cooling method. Amino acids like glycine, L-alanine, and L-valine have been selected for doping. Optical quality bulk crystals have been harvested after a typical growth period of about twenty days. The effect of amino acids in the crystal lattice and molecular vibrational frequencies of various functional groups in the crystals have been studied using X-ray powder diffraction and Fourier Transform infrared (FTIR) analyses respectively. Thermal behavior of the amino acids mixed LAP crystals have been studied from the TG and DTG analyses. High-resolution X-ray diffraction studies have been carried out to find the crystalline nature. Optical transmission studies have been carried out by UV-vis spectrophotometer. The cut off wavelength is below 240 nm for the grown crystals.

  8. A peek into the history of sapphire crystal growth

    Science.gov (United States)

    Harris, Daniel C.

    2003-09-01

    After the chemical compositions of sapphire and ruby were unraveled in the middle of the 19th century, chemists set out to grow artificial crystals of these valuable gemstones. In 1885 a dealer in Geneva began to sell ruby that is now believed to have been created by flame fusion. Gemnologists rapidly concluded that the stones were artificial, but the Geneva ruby stimulated A. V. L. Verneuil in Paris to develop a flame fusion process to produce higher quality ruby and sapphire. By 1900 there was brisk demand for ruby manufactured by Verneuil's method, even though Verneuil did not publicly announce his work until 1902 and did not publish details until 1904. The Verneuil process was used with little alteration for the next 50 years. From 1932-1953, S. K. Popov in the Soviet Union established a capability for manufacturing high quality sapphire by the Verneuil process. In the U.S., under government contract, Linde Air Products Co. implemented the Verneuil process for ruby and sapphire when European sources were cut off during World War II. These materials were essential to the war effort for jewel bearings in precision instruments. In the 1960s and 1970s, the Czochralski process was implemented by Linde and its successor, Union Carbide, to make higher crystal quality material for ruby lasers. Stimulated by a government contract for structural fibers in 1966, H. LaBelle invented edge-defined film-fed growth (EFG). The Saphikon company, which is currently owned by Saint-Gobain, evolved from this effort. Independently and simultaneously, Stepanov developed edge-defined film-fed growth in the Soviet Union. In 1967 F. Schmid and D. Viechnicki at the Army Materials Research Lab grew sapphire by the heat exchanger method (HEM). Schmid went on to establish Crystal Systems, Inc. around this technology. Rotem Industries, founded in Israel in 1969, perfected the growth of sapphire hemispheres and near-net-shape domes by gradient solidification. In the U.S., growth of near

  9. Growth of high quality bulk size single crystals of inverted solubility lithium sulphate monohydrate

    Energy Technology Data Exchange (ETDEWEB)

    Silambarasan, A.; Rajesh, P., E-mail: rajeshp@ssn.edu.in; Ramasamy, P. [Center for Crystal Growth, SSN College of Engineering, Kalavakkam-603110 (India)

    2015-06-24

    The paper summarizes the processes of growing large lithium sulfate monohydrate (LSMH) single crystals. We have established a procedure to grow high quality bulk size single crystals of inverted solubility LSMH by a newly developed unidirectional crystallization technique called the Sankeranarayenan - Ramasamy (SR) method. The convective flow of crystal growth processes from solution and the conditions of growing crystals of various aspects were discussed. Good quality LSMH single crystal is grown of the size 20 mmX80 mm without cracks, localized-defects and inclusions. The as-grown crystals are suitable for piezoelectric and nonlinear optical applications.

  10. EFFECT OF SODIUM DODECYLBENZENESULFONIC ACID (SDBS ON THE GROWTH RATE AND MORPHOLOGY OF BORAX CRYSTAL

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available An investigation of the effect of sodium dodecylbenzenesulfonic acid (SDBS on both growth rate and morphology of borax crystal has been carried out.  This experiment was carried out at temperature of 25 °C and relative supersaturation of 0.21 and 0.74 under in situ cell optical microscopy method.  The result shows that SDBS inhibits the growth rate and changes the morphology of borax crystal.   Keywords: Borax; growth rate; crystallization, SDBS

  11. Electromelt furnace evaluation

    International Nuclear Information System (INIS)

    Reimann, G.A.; Welch, J.M.

    1981-09-01

    An electromelt furnace was designed, built, and operated at the Idaho National Engineering Laboratory to demonstrate the suitability of this equipment for large-scale processing of radioactive wastes in iron-enriched basalt. Several typical waste compositions were melted and cast. The furnace was disassembled and the components evaluated. Calcines and fluorides attacked the furnace lining, unoxidized metals accumulated under the slag, and electrode attrition was high

  12. The performance studies of DKDP crystals grown by a rapid horizontal growth method

    Science.gov (United States)

    Xie, Xiaoyi; Qi, Hongji; Wang, Bin; Wang, Hu; Chen, Duanyang; Shao, Jianda

    2018-04-01

    A deuterated potassium dihydrogen phosphate (DKDP) crystal with about 70% deuterium level was grown by a rapid horizontal growth method with independent design equipment, which includes a continuous filtration system. The cooling program during crystal growth was designed according to a self-developed software to catch the size of growing crystal in real time. The crystal structure, optical performance and laser induced damage threshold (LIDT) of this DKDP crystal were investigated in this paper. The deuterium concentration of the crystal was confirmed by the neutron diffraction technique, which was effective and available in determining a complete range of deuteration level. The dielectric property was measured to evaluate the perfection of the lattice. The transmittance and LIDT were carried out further to evaluate the optical and functional properties of this DKDP crystal grown in the rapid horizontal growth technique. All of the detailed characterization for DKDP figured out that the 70% deuterated KDP crystal grown in this way had relatively good qualities.

  13. Investigation of grain competitive growth during directional solidification of single-crystal nickel-based superalloys

    International Nuclear Information System (INIS)

    Zhao, Xinbao; Liu, Lin; Zhang, Jun

    2015-01-01

    Grain competitive growth of nickel-based single-crystal superalloys during directional solidification was investigated. A detailed characterization of bi-crystals' competitive growth was performed to explore the competitive grain evolution. It was found that high withdrawal rate improved the efficiency of grain competitive growth. The overgrowth rate was increased when the misorientation increased. Four patterns of grain competitive growth with differently oriented dispositions were characterized. The results indicated that the positive branching of the dendrites played a significant role in the competitive growth process. The effect of crystal orientation and heat flow on the competitive growth can be attributed to the blocking mechanism between the adjacent grains. (orig.)

  14. Growth, morphology, spectral and thermal studies of gel grown diclofenac acid crystals

    Science.gov (United States)

    Ramachandran, E.; Ramukutty, S.

    2014-03-01

    The crystal growth of diclofenac acid in silica gel is the first to be reported in literature. The growth parameters were varied to optimize the suitable growth condition. Single crystal X-ray diffraction method was used for the conformation of the crystal structure. Morphology studies showed that the growth is prominent along the b-axis and the prominent face is {002}. Fourier transform infrared spectral study was performed to identify the functional groups present in the crystal. Thermal stability and decomposition of the material were analyzed using thermo calorimetry in the temperature range 30-500 °C.

  15. Growth of cadmium oxide whiskers on cadmium sulphide single crystals with copper as growth activator

    International Nuclear Information System (INIS)

    Koparanova, N.; Simov, S.

    1985-01-01

    Some results on the growth and morphology of cadmium oxide whiskers, obtained on cadmium sulphide single crystals with copper as a growth activator, are presented in this work. Cadmium oxide whiskers have been obtained on brace 112-bar0 brace faces of cadmium sulphide plates with a copper layer deposited in advance. The whiskers grew during the annealing of the plates in a weak stream of technically pure argon at temperatures 670 to 730 deg C for 15 min to 3.5 h. Details about the procedure have been given elsewhere. The composition and morphology of the whiskers have been studied by an X-ray microanalyser JEOL 35 DDS and a scanning electron microscope JEOL, JSM 35. The optical microscopic observations have shown that after annealing, a gray-black granular layer is formed on the cadmium sulphide single crystals and this layer can easily be separated from the crystal substrate. Under the granular layer the crystal is heavily damaged. The whiskers grow on the granular layer and they are coloured yellow-brown or red-brown. The maximum whisker length attains several hundreds of micrometres and in some cases up to 1 mm or more. (author)

  16. Growth of cadmium oxide whiskers on cadmium sulphide single crystals with copper as growth activator

    Energy Technology Data Exchange (ETDEWEB)

    Koparanova, N.; Simov, S. (Bylgarska Akademiya na Naukite, Sofia. Inst. po Fizika na Tvyrdoto Tyalo); Genchev, D. (Bylgarska Akademiya na Naukite, Sofia. Inst. za Yadrena Izsledvaniya i Yadrena Energetika); Metchenov, G. (Research Inst. of Criminalistics and Criminology, Sofia (Bulgaria))

    1985-02-01

    Some results on the growth and morphology of cadmium oxide whiskers, obtained on cadmium sulphide single crystals with copper as a growth activator, are presented in this work. Cadmium oxide whiskers have been obtained on brace 112-bar0 brace faces of cadmium sulphide plates with a copper layer deposited in advance. The whiskers grew during the annealing of the plates in a weak stream of technically pure argon at temperatures 670 to 730 deg C for 15 min to 3.5 h. Details about the procedure have been given elsewhere. The composition and morphology of the whiskers have been studied by an X-ray microanalyser JEOL 35 DDS and a scanning electron microscope JEOL, JSM 35. The optical microscopic observations have shown that after annealing, a gray-black granular layer is formed on the cadmium sulphide single crystals and this layer can easily be separated from the crystal substrate. Under the granular layer the crystal is heavily damaged. The whiskers grow on the granular layer and they are coloured yellow-brown or red-brown. The maximum whisker length attains several hundreds of micrometres and in some cases up to 1 mm or more.

  17. Helical growth of aluminum nitride: new insights into its growth habit from nanostructures to single crystals.

    Science.gov (United States)

    Zhang, Xing-Hong; Shao, Rui-Wen; Jin, Lei; Wang, Jian-Yu; Zheng, Kun; Zhao, Chao-Liang; Han, Jie-Cai; Chen, Bin; Sekiguchi, Takashi; Zhang, Zhi; Zou, Jin; Song, Bo

    2015-05-15

    By understanding the growth mechanism of nanomaterials, the morphological features of nanostructures can be rationally controlled, thereby achieving the desired physical properties for specific applications. Herein, the growth habits of aluminum nitride (AlN) nanostructures and single crystals synthesized by an ultrahigh-temperature, catalyst-free, physical vapor transport process were investigated by transmission electron microscopy. The detailed structural characterizations strongly suggested that the growth of AlN nanostructures including AlN nanowires and nanohelixes follow a sequential and periodic rotation in the growth direction, which is independent of the size and shape of the material. Based on these experimental observations, an helical growth mechanism that may originate from the coeffect of the polar-surface and dislocation-driven growth is proposed, which offers a new insight into the related growth kinetics of low-dimensional AlN structures and will enable the rational design and synthesis of novel AlN nanostructures. Further, with the increase of temperature, the growth process of AlN grains followed the helical growth model.

  18. Growth of single-crystal YAG fiber optics.

    Science.gov (United States)

    Nie, Craig D; Bera, Subhabrata; Harrington, James A

    2016-07-11

    Single-crystal YAG (Y3Al5O12) fibers have been grown by the laser heated pedestal growth technique with losses as low as 0.3 dB/m at 1.06 μm. These YAG fibers are as long as about 60 cm with diameters around 330 μm. The early fibers were grown from unoriented YAG seed fibers and these fibers exhibited facet steps or ridges on the surface of the fiber. However, recently we have grown fibers using an oriented seed to grow step-free fibers. Scattering losses made on the fibers indicate that the scattering losses are equal to about 30% of the total loss.

  19. The averaged face growth rates of lysozyme crystals: the effect of temperature

    Science.gov (United States)

    Nadarajah, Arunan; Forsythe, Elizabeth L.; Pusey, Marc L.

    1995-05-01

    Measurements of the averaged or macroscopic face growth rates of lysozyme crystals are reported here for the (110) face of tetragonal lysozyme, at three sets of pH and salt concentrations, with temperatures over a 4-22°C range for several protein concentrations. The growth rate trends with supersaturation were similar to previous microscopic growth rate measurements. However, it was found that at high supersaturations the growth rates attain a maximum and then start decreasing. No "dead zone" was observed but the growth rates were found to approach zero asymptotically at very low supersaturations. The growth rate data also displayed a dependence on pH and salt concentration which could not be characterized solely by the supersaturation. A complete mechanism for lysozyme crystal growth, involving the formation of an aggregate growth unit, mass transport of the growth unit to the crystal interface and faceted crystal growth by growth unit addition, is suggested. Such a mechanism may provide a more consistent explanation for the observed growth rate trends than those suggested by other investigators. The nutrient solution interactions leading to the formation of the aggregate growth unit may, thus, be as important as those occurring at the crystal interface and may account for the differences between small molecule and protein crystal growth.

  20. Growth of 2-amino-5-chlorobenzophenone single crystal by ...

    Indian Academy of Sciences (India)

    Abstract. Organic single crystals of 2-amino-5-chlorobenzophenone (2A5CB) were grown by Microtube Czochral- ski method using Microtube as a seed. The grown crystals were characterized by single crystal and powder X-ray diffraction. The functional groups of the grown crystal were found using Fourier transform ...

  1. Growth and Characterization of ZnTe Crystal

    International Nuclear Information System (INIS)

    Nann Thazin

    2011-12-01

    High quality ZnTe crystals have been synthesized by vapor Transport method. The grown crystals were p-type. The concentration and mobility were 2.5 x 10 16 cm-3 and 23 cm2/Vs at 300K, according to Hall effect measurements. Surface morphology of the crystal was investigated by scanning electron microscope (SEM). Crystal orientation and lattice parameters of the crystals were also analysed by XRD. From X-ray diffraction studies the structure of the grown crystals were found to be zinc-blende. The crystal emitted light in the visible range at room temperature.

  2. Crystal growth, crystal structure and physical characterization of CeMo/sub 6/S/sub 8/

    International Nuclear Information System (INIS)

    Pena, O.; Geantet, C.; Hortyn, R.; Potel, M.; Padiou, J.; Sergent, M.

    1987-01-01

    Single crystals of Ce/sub x/Mo/sub 6/S/sub 8/ were grown using two methods of crystal growth. Refinement of the crystal structure shows an upper stoichiometry of x = 1.0. The cerium atom occupies the origin site of the hexagonal-rhombohedral unit-cell, with no visible delocalization. Crystals were characterized through their susceptibility and transport properties. A.c. susceptibility shows a smooth ''shoulder'' at 2.4 K, due to a magnetic order. The resistivity of a single crystal presents a minimum at 19 K, followed by a small logarithmic increase with decreasing temperature, and a sharp decrease between 2.7 and 2.4 K. These results on single crystals are discussed in comparison with previous reports on sintered powder

  3. Investigation on the bulk growth of α-LiIO 3 single crystals and the ...

    Indian Academy of Sciences (India)

    2017-07-26

    Jul 26, 2017 ... (a) Solubility of LiIO3 in aqueous solvent, (b) spurious crystals at the bottom of the growth vessel and (c) the harvested spurious crystals. ..... 20. Small spot. 25. 8–9. Big spot with crack parts of the grown crystal. As LiIO3 is an indirect bandgap material, the optical bandgap (Eg) has been estimated from the.

  4. Crystal growth iron based pnictide compounds; Kristallzuechtung eisenbasierter Pniktidverbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Nacke, Claudia

    2012-11-15

    The present work is concerned with selected crystal growth method for producing iron-based superconductors. The first part of this work introduces significant results of the crystal growth of BaFe{sub 2}As{sub 2} and the cobalt-substituted compound Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} with x{sub Nom} = 0.025, 0.05, 0.07, 0.10 and 0.20. For this purpose a test procedure for the vertical Bridgman method was developed. The second part of this work contains substantial results for growing a crystal of LiFeAs and the nickel-substituted compound Li{sub 1-δ}Fe{sub 1-x}Ni{sub x}As with x{sub Nom} = 0.015, 0.025, 0.05, 0.06, 0.075 and 0.10. For this purpose a test procedure for the melt flow process has been developed successfully. [German] Die vorliegende Arbeit befasst sich mit ausgewaehlten Kristallzuechtungsverfahren zur Herstellung eisenbasierter Supraleiter. Der erste Teil dieser Arbeit fuehrt wesentliche Ergebnisse der Kristallzuechtung von BaFe{sub 2}As{sub 2} sowie der Cobalt-substituierten Verbindung Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} mit x{sub Nom} =0.025, 0.05, 0.07, 0.10 und 0.20 auf. Hierzu wurde eine Versuchsdurchfuehrung fuer das vertikale Bridgman-Verfahren konzipiert, mit welcher erfolgreich Kristalle dieser Zusammensetzungen gezuechtet wurden. Der zweite Teil dieser Arbeit enthaelt wesentliche Ergebnisse zur Kristallzuechtung von LiFeAs sowie der Nickel-substituierten Verbindung Li{sub 1-δ}Fe{sub 1-x}Ni{sub x}As mit x{sub Nom} = 0.015, 0.025, 0.05, 0.06, 0.075 und 0.10. Hierfuer wurde erfolgreich eine Versuchsdurchfuehrung fuer das Schmelzfluss-Verfahren entwickelt.

  5. Synthesis, crystal growth, optical, thermal, and mechanical properties of a nonlinear optical single crystal: ammonium sulfate hydrogen sulphamate (ASHS)

    Science.gov (United States)

    Sudhakar, K.; Nandhini, S.; Muniyappan, S.; Arumanayagam, T.; Vivek, P.; Murugakoothan, P.

    2018-04-01

    Ammonium sulfate hydrogen sulphamate (ASHS), an inorganic nonlinear optical crystal, was grown from the aqueous solution by slow evaporation solution growth technique. The single-crystal XRD confirms that the grown single crystal belongs to the orthorhombic system with the space group of Pna21. Powder XRD confirms the crystalline nature and the diffraction planes were indexed. Crystalline perfection of grown crystal was analysed by high-resolution X-ray diffraction rocking curve technique. UV-Vis-NIR studies revealed that ASHS crystal has optical transparency 65% and lower cut-off wavelength at 218 nm. The violet light emission of the crystal was identified by photoluminescence studies. The particle size-dependent second-harmonic generation efficiency for ASHS crystal was evaluated by Kurtz-Perry powder technique using Nd:YAG laser which established the existence of phase matching. Surface laser damage threshold value was evaluated using Nd:YAG laser. Optical homogeneity of the crystal was evaluated using modified channel spectrum method through birefringence study. Thermal analysis reveals that ASHS crystal is stable up to 213 °C. The mechanical behaviour of the ASHS crystal was analysed using Vickers microhardness study.

  6. Kinetic Roughening and Energetics of Tetragonal Lysozyme Crystal Growth: A Preliminary Atomic Force Microscopy Investigation

    Science.gov (United States)

    Gorti, Sridhar; Forsythe, Elizabeth L.; Pusey, Marc L.

    2004-01-01

    We examined particulars of crystal growth from measurements obtained at both microscopic and molecular levels. The crystal growth measurements performed at the microscopic level are well characterized by a model that balances the flux of macromolecules towards the crystal surface with the flux of the crystal surface. Numerical evaluation of model with measurements of crystal growth, in time, provided accurate estimates for the average growth velocities. Growth velocities thus obtained were also interpreted using well-established phenomenological theories. Moreover, we find that microscopic measurements of growth velocity measurements obtained as a function of temperature best characterizes changes in crystal growth modes, when present. We also examined the possibility of detecting a change in crystal growth modes at the molecular level using atomic force microscopy, AFM. From preliminary AFM measurements performed at various supersaturations, we find that magnitude of surface height fluctuations, h(x), increases with supersaturation. Further examination of surface height fluctuations using methods established for fluctuation spectroscopy also enabled the discovery of the existence of a characteristic length, c, which may possibly determine the mode of crystal growth. Although the results are preliminary, we establish the non- critical divergence of 5 and the root-mean-square (rms) magnitude of height-height fluctuations as the kinetic roughening transition temperatures are approached. Moreover, we also examine approximate models for interpreting the non-critical behavior of both 6 and rms magnitude of height-height fluctuations, as the solution supersaturation is increased towards the kinetic roughening supersaturation.

  7. A theoretical model describing the one-dimensional growth of single crystals on free sustained substrates

    Science.gov (United States)

    Ye, Ziran; Wang, Ke; Lu, Chenxi; Jin, Ying; Sui, Chenghua; Yan, Bo; Gao, Fan; Cai, Pinggen; Lv, Bin; Li, Yun; Chen, Naibo; Sun, Guofang; Xu, Fengyun; Ye, Gaoxiang

    2018-03-01

    We develop a theoretical model that interprets the growth mechanism of zinc (Zn) crystal nanorods on a liquid substrate by thermal evaporation. During deposition, Zn atoms diffuse randomly on an isotropic and quasi-free sustained substrate, the nucleation of the atoms results in the primary nanorod (or seed crystal) growth. Subsequently, a characteristic one-dimensional atomic aggregation is proposed, which leads to the accelerating growth of the crystal nanorod along its preferential growth direction until the growth terminates. The theoretical results are in good agreement with the experimental findings.

  8. Raman spectrum analysis on the solid-liquid boundary layer of BGO crystal growth

    International Nuclear Information System (INIS)

    Zhang Xia; Yin Shaotang; Wan Songming; Zhang Qingli; You Jinglin; Chen Hui; Zhao Sijie

    2007-01-01

    We study the Raman spectra of Bi 4 Ge 3 O 12 crystal at different temperatures, as well as its melt. The structure characters of the single crystal, melt and growth solid-liquid boundary layer of BGO are investigated by their high-temperature Raman spectra for the first time. The rule of structure change of BGO crystal with increasing temperature is analysed. The results show that there exists [GeO 4 ] polyhedral structure and Bi ion independently in BGO melt. The bridge bonds Bi-O-Bi and Bi-O-Ge appear in the crystal and at the boundary layer, but disappear in the melt. The structure of the growth solid-liquid boundary layer is similar to that of BGO crystal. In the melt, the long-range order structure of the crystal disappears. The thickness of the growth solid-liquid boundary layer of BGO crystal is about 50 μm. (authors)

  9. Advanced steel reheat furnace

    Energy Technology Data Exchange (ETDEWEB)

    Moyeda, D.; Sheldon, M.; Koppang, R. [Energy and Environmental Research Corp., Irvine, CA (United States); Lanyi, M.; Li, X.; Eleazer, B. [Air Products and Chemicals, Inc., Allentown, PA (United States)

    1997-10-01

    Energy and Environmental Research Corp. (EER) under a contract from the Department of Energy is pursuing the development and demonstration of an Advanced Steel Reheating Furnace. This paper reports the results of Phase 1, Research, which has evaluated an advanced furnace concept incorporating two proven and commercialized technologies previously applied to other high temperature combustion applications: EER`s gas reburn technology (GR) for post combustion NOx control; and Air Product`s oxy-fuel enrichment air (OEA) for improved flame heat transfer in the heating zones of the furnace. The combined technologies feature greater production throughput with associated furnace efficiency improvements; lowered NOx emissions; and better control over the furnace atmosphere, whether oxidizing or reducing, leading to better control over surface finish.

  10. Crystal growth of new charge-transfer salts based on π-conjugated donor molecules

    Energy Technology Data Exchange (ETDEWEB)

    Morherr, Antonia, E-mail: morherr@stud.uni-frankfurt.de [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Witt, Sebastian [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Chernenkaya, Alisa [Graduate School Materials Science in Mainz, 55128 Mainz (Germany); Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz (Germany); Bäcker, Jan-Peter [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Schönhense, Gerd [Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz (Germany); Bolte, Michael [Institut für anorganische Chemie, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany); Krellner, Cornelius [Physikalisches Institut, Goethe-Universität Frankfurt am Main, 60438 Frankfurt am Main (Germany)

    2016-09-01

    New charge transfer crystals of π-conjugated, aromatic molecules (phenanthrene and picene) as donors were obtained by physical vapor transport. The melting behavior, optimization of crystal growth and the crystal structure are reported for charge transfer salts with (fluorinated) tetracyanoquinodimethane (TCNQ-F{sub x}, x=0, 2, 4), which was used as acceptor material. The crystal structures were determined by single-crystal X-ray diffraction. Growth conditions for different vapor pressures in closed ampules were applied and the effect of these starting conditions for crystal size and quality is reported. The process of charge transfer was investigated by geometrical analysis of the crystal structure and by infrared spectroscopy on single crystals. With these three different acceptor strengths and the two sets of donor materials, it is possible to investigate the distribution of the charge transfer systematically. This helps to understand the charge transfer process in this class of materials with π-conjugated donor molecules.

  11. LSA Large Area Silicon Sheet Task. Continuous Liquid Feed Czochralski Growth. [for solar cell fabrication

    Science.gov (United States)

    Fiegl, G.

    1979-01-01

    The design and development of equipment and processes to demonstrate continuous growth of crystals by the Czochralski method suitable for producing single silicon crystals for use in solar cells is presented. The growth of at least 150 kg of mono silicon crystal, 150 mm in diameter is continuous from one growth container. A furnace with continuous liquid replenishment of the growth crucible, accomplished by a meltdown system with a continuous solid silicon feed mechanism and a liquid transfer system, with associated automatic feedback controls is discussed. Due to the silicon monoxide build up in the furnace and its retarding effect on crystal growth the furnace conversion for operation in the low pressure range is described. Development of systems for continuous solid recharging of the meltdown chamber for various forms of poly silicon is described.

  12. Second harmonic chalcone crystal: Synthesis, growth and characterization

    Energy Technology Data Exchange (ETDEWEB)

    D' Silva, E.D., E-mail: deepak.dsilva@gmail.co [Department of studies in Physics, Mangalore University, Mangalagangotri, Mangalore 574199 (India); Narayan Rao, D. [School of Physics, University of Hyderabad, Hyderabad 500046 (India); Philip, Reji [Light and Matter Physics Group, Raman Research Institute, Bangalore 560080 (India); Butcher, Ray J. [Department of Chemistry, Howard University, Washington, DC 20059 (United States); Rajnikant [Department of Physics and Electronics, University of Jammu, Jammu Tawi 180006 (India); Dharmaprakash, S.M. [Department of studies in Physics, Mangalore University, Mangalagangotri, Mangalore 574199 (India)

    2011-05-15

    The novel nonlinear optical chalcone derivative (2E)-3-[4-(methylsulfanyl)phenyl]-1-(3-bromophenyl)prop-2-en-1-one (3Br4MSP) crystals have been grown by slow evaporation technique at ambient temperature. The crystal was subjected to different types of characterization method in order to study its possible application in nonlinear optics. The structure determination of the grown crystal was done by single crystal X-ray diffraction study. The morphology of the crystal is studied. The crystal was subjected to thermal analysis to find its thermal stability. The grown crystals were characterized for their optical transmission and mechanical hardness. The second harmonic generation (SHG) efficiency of the crystal is obtained by classical powdered technique. The laser damage threshold for 3Br4MSP crystal was determined using Q-switched Nd:YAG laser.

  13. Growth and characterization of 2-methylquinolinium L-malate single crystal

    Science.gov (United States)

    Bharathi, M. Divya; Ahila, G.; Mohana, J.; Anbalagan, G.

    2017-05-01

    An organic nonlinear optical single crystal, 2-methylquinolinium L-malate (MLM) was grown from ethanol solvent using slow evaporation solution growth technique. The single crystal X-ray diffraction studies confirmed that the crystal belongs to the monoclinic system with the non-centrosymmetric space group P21. The crystal is transparent in the entire visible region. The second harmonic generation efficiency of the grown crystal has been obtained by the Kurtz-Perry powder technique. The laser damage threshold value 5.58 GW/cm2 indicates that this crystal can be used for high-power laser applications.

  14. A Simple Inexpensive Bridgman-Stockbarger Crystal Growth System for Organic Materials

    Science.gov (United States)

    Choi, J.; Aggarwal, M. D.; Wang, W. S.; Metzl, R.; Bhat, K.; Penn, Benjamin G.; Frazier, Donald O.

    1996-01-01

    Direct observation of solid-liquid interface is important for the directional solidification to determine the desired interface shape by controlling the growth parameters. To grow good quality single crystals of novel organic nonlinear optical materials, a simple inexpensive Bridgman-Stockbarger (BS) crystal growth system has been designed and fabricated. Two immiscible liquids have been utilized to create two zones for this crystal growth system. Bulk single crystals of benzil derivative and n-salicylidene-aniline have been successfully grown in this system. The optimum lowering rate has been found to be 0.1 mm/h for the flat interface. Results on the crystal growth and other parameters of the grown crystals are presented.

  15. Electron microscopy of crystalline solids and non-classical crystal growth

    OpenAIRE

    Greer, Heather Frances

    2013-01-01

    This project concerns the non-classical crystal growth of various porous and non-porous materials. In order to determine their crystal growth mechanism, the reaction was stopped at several different reaction times with the size, morphology, crystal structure and orientation of the particles analysed using scanning electron microscopy and high resolution transmission electron microscopy as the principal characterisation techniques. Other techniques used include X-ray diffraction, energy disper...

  16. Growth and time dependent alignment of KCl crystals in Hemoglobin LB monolayer

    International Nuclear Information System (INIS)

    Mahato, Mrityunjoy; Pal, Prabir; Tah, Bidisha; Kamilya, Tapanendu; Talapatra, G.B.

    2012-01-01

    Nature and organism often use the biomineralization technique to build up various highly regular structures such as bone, teeth, kidney stone etc., and recently this becomes the strategy to design and synthesis of novel biocomposite materials. We report here the controlled crystallization of KCl in Langmuir and Langmuir Blodgett (LB) monolayer of Hemoglobin (Hb) at ambient condition. The nucleation and growth of KCl crystals in Hb monolayer has temporal and KCl concentration dependency. The growth of KCl crystals in LB film of Hb has distinct behavior in the alignment of crystals from linear to fractal like structures depending on growth time. The crystallographic identity of the biomineralized KCl crystal is confirmed from HR-TEM, XRD, and from powder diffraction simulation. Our results substantiated that the template of Langmuir monolayer of proteins plays a crucial role in biomineralization as well as in designing and synthesizing of novel biocomposite materials. Highlights: ► Biomineralization of KCl crystal has been studied in Hemoglobin LB film. ► KCl crystal growth is time and concentration of KCl dependent. ► The alignment of KCl crystal growth is fractal nature with time. ► The unfolding of Hb and evaporation factor has some role in crystallization and fractal growth.

  17. Crystal growth of an organic non-linear optical material from the vapour phase

    International Nuclear Information System (INIS)

    Hou, W.

    1999-01-01

    Due to the potential applications of organic non-linear optical materials in the areas of optical processing and communication, the investigation of the crystal growth of new organic NLO materials has been an active field for the last 20 years. For such uses it is necessary to produce single crystals of high quality and perfection, free of strain and defects. When crystals are grown from the solution and the melt, solvent and the decomposition component in the melt can introduce impurities and imperfection to the as-grown crystals. For crystals grown from vapour phase, in the absence of the solvent, this cannot occur and the method promises to yield single crystals of higher quality. Despite this attraction, little attention has been paid to the vapour phase growth of organic NLO crystals. It was with this in mind that the following investigation was carried out. Using Methyl p-hydroxybenzoate (p-MHB), a potential organic NLO material, a comparison investigation was made of its crystal growth from both the vapour phase and solution; this included an examination of morphological assessment, structural perfection, surface morphology and growth kinetics of the as-grown crystals and the mass transport properties in the growth ampoule. Collation of this data allows the definition of the best conditions for vapour phase growth to produce specimens of high quality and purity. (author)

  18. Investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium crystals by the Czochralski method

    International Nuclear Information System (INIS)

    Budenkova, O. N.; Vasiliev, M. G.; Yuferev, V. S.; Ivanov, I. A.; Bul'kanov, A. M.; Kalaev, V. V.

    2008-01-01

    Numerical investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium garnet crystals in the same thermal zone and comparison of the obtained results with the experimental data have been performed. It is shown that the difference in the behavior of the crystallization front during growth of the crystals is related to their different transparency in the IR region. In gadolinium gallium garnet crystals, which are transparent to thermal radiation, a crystallization front, strongly convex toward the melt, is formed in the growth stage, which extremely rapidly melts under forced convection. Numerical analysis of this process has been performed within the quasistationary and nonstationary models. At the same time, in terbium gallium garnet crystals, which are characterized by strong absorption of thermal radiation, the phase boundary shape changes fairly smoothly and with a small amplitude. In this case, as the crystal is pulled, the crystallization front tends to become convex toward the crystal bulk.

  19. Extracellular matrix protein in calcified endoskeleton: a potential additive for crystal growth and design

    Science.gov (United States)

    Azizur Rahman, M.; Fujimura, Hiroyuki; Shinjo, Ryuichi; Oomori, Tamotsu

    2011-06-01

    In this study, we demonstrate a key function of extracellular matrix proteins (ECMPs) on seed crystals, which are isolated from calcified endoskeletons of soft coral and contain only CaCO 3 without any living cells. This is the first report that an ECMP protein extracted from a marine organism could potentially influence in modifying the surface of a substrate for designing materials via crystallization. We previously studied with the ECMPs from a different type of soft coral ( Sinularia polydactyla) without introducing any seed crystals in the process , which showed different results. Thus, crystallization on the seed in the presence of ECMPs of present species is an important first step toward linking function to individual proteins from soft coral. For understanding this interesting phenomenon, in vitro crystallization was initiated in a supersaturated solution on seed particles of calcite (1 0 4) with and without ECMPs. No change in the crystal growth shape occurred without ECMPs present during the crystallization process. However, with ECMPs, the morphology and phase of the crystals in the crystallization process changed dramatically. Upon completion of crystallization with ECMPs, an attractive crystal morphology was found. Scanning electron microscopy (SEM) was utilized to observe the crystal morphologies on the seeds surface. The mineral phases of crystals nucleated by ECMPs on the seeds surface were examined by Raman spectroscopy. Although 50 mM Mg 2+ is influential in making aragonite in the crystallization process, the ECMPs significantly made calcite crystals even when 50 mM Mg 2+ was present in the process. Crystallization with the ECMP additive seems to be a technically attractive strategy to generate assembled micro crystals that could be used in crystals growth and design in the Pharmaceutical and biotechnology industries.

  20. Crystallization Kinetics of Organic–Inorganic Trihalide Perovskites and the Role of the Lead Anion in Crystal Growth

    KAUST Repository

    Moore, David T.

    2015-02-18

    © 2015 American Chemical Society. Methylammonium lead halide perovskite solar cells continue to excite the research community due to their rapidly increasing performance which, in large part, is due to improvements in film morphology. The next step in this progression is control of the crystal morphology which requires a better fundamental understanding of the crystal growth. In this study we use in situ X-ray scattering data to study isothermal transformations of perovskite films derived from chloride, iodide, nitrate, and acetate lead salts. Using established models we determine the activation energy for crystallization and find that it changes as a function of the lead salt. Further analysis enabled determination of the precursor composition and showed that the primary step in perovskite formation is removal of excess organic salt from the precursor. This understanding suggests that careful choice of the lead salt will aid in controlling crystal growth, leading to superior films and better performing solar cells.

  1. Crystal growth, electrical and photophysical properties of Tl2S ...

    Indian Academy of Sciences (India)

    The Tl2S compound was prepared in a single crystal form using a special local technique, and the obtained crystals were analysed by X-ray diffraction. For the resultant crystals, the electrical properties (electrical conductivity and Hall effect) and steady-state photoconductivity were elucidated in this work. The electrical ...

  2. Crystal growth and structural analysis of zirconium sulphoselenide ...

    Indian Academy of Sciences (India)

    The grown crystals were examined under optical zoom microscope for their surface topography study. Hall effect measurements were carried out on grown crystals at room temperature. The negative value of Hall coefficient implies that these crystals are -type in nature. The conductivity is found to decrease with increase of ...

  3. Protein Crystal Growth in Gels and Stationary Magnetic Fields

    International Nuclear Information System (INIS)

    Moreno, A.; Quiroz-Garcia, B.; Yokaichiya, F.; Stojanoff, V.; Rudolph, P.

    2007-01-01

    Thaumatin, lysozyme, and ferritin single crystals were grown in solutions and gels without and with surrounding strong stationary magnetic fields. The crystal size, number and alignment in dependence on the induction force were analyzed. The crystal quality, like mosaicity, as function of the magnetic force is discussed by using synchrotron X-ray diffraction analysis

  4. Growth of strontium oxalate crystals in agar–agar gel

    Indian Academy of Sciences (India)

    single diffusion technique in which the gel medium does. Figure 4. a. Transparent prismatic bi-pyramidal platy shaped crystals at interstitial and spherulite crystals well inside test-tube using NH4Cl additive in single diffusion and b. some good quality crystals obtained using NH4Cl as addictive in single diffusion.

  5. Progress in art and science of crystal growth and its impacts on modern society

    Science.gov (United States)

    Nishinaga, Tatau

    2015-05-01

    The impacts of the progress in the art and science of crystal growth on human life are reviewed. Even before the invention of the transistor, quartz and corundum crystals were used as crystal oscillators and jewel bearings, respectively. However, a major impact of crystal growth on society was experienced with the invention of the transistor, which required high-purity and perfect germanium crystals. Once the importance of crystal growth was clearly recognized, the science of crystal growth also extensively developed. The growth of single crystalline silicon allows us to produce integrated circuits, which are used in all the electronic devices in everyday use. The technological developments in the growth of compound semiconductors have also had a large impact on society through the inventions of the laser diode for optical communication and the p-n junction nitride light-emitting diode toward the realization of a less energy-intensive society. The latter invention was awarded the 2014 Nobel Prize in Physics. Finally, future aspects of crystal growth are discussed.

  6. Calculations in furnace technology

    CERN Document Server

    Davies, Clive; Hopkins, DW; Owen, WS

    2013-01-01

    Calculations in Furnace Technology presents the theoretical and practical aspects of furnace technology. This book provides information pertinent to the development, application, and efficiency of furnace technology. Organized into eight chapters, this book begins with an overview of the exothermic reactions that occur when carbon, hydrogen, and sulfur are burned to release the energy available in the fuel. This text then evaluates the efficiencies to measure the quantity of fuel used, of flue gases leaving the plant, of air entering, and the heat lost to the surroundings. Other chapters consi

  7. The inhibition of crystal growth of mirabilite in aqueous solutions in the presence of phosphonates

    Science.gov (United States)

    Vavouraki, A. I.; Koutsoukos, P. G.

    2016-02-01

    The formation of sodium sulfate decahydrate (Mirabilite) has been known to cause serious damages to structural materials both of modern and of historical buildings. Methods which can retard or completely suppress the development of mirabilte crystals are urgently needed especially as remedies or preventive measures for the preservation of the built cultural heritage. In the present work we present results on the effect of the presence of phosphonate compounds on the kinetics of crystal growth from aqueous supersaturated solutions at 18 °C using the seeded growth technique. The phosphonate compounds tested differed with respect to the number of ionizable phosphonate groups and with respect to the number of amino groups in the respective molecules. The crystal growth process was monitored by the temperature changes during the exothermic crystallization of mirabilite in the stirred supersaturated solutions. The crystal growth of mirabilite in the presence of: (1-hydroxyethylidene)-1, 1-diphosphonic acid (HEDP), amino tri (methylene phosphonic acid) (ATMP), hexamethylenediaminetetra (methylene)phosphonic acid (HTDMP), and diethylene triamine penta(methylene phosphonic acid)(DETPMP) over a range of concentrations between 0.1-5% w/w resulted in significant decrease of the rates of mirabilite crystal growth. All phosphonic compounds tested reduced the crystallization rates up to 60% in comparison with additive-free solutions. The presence of the test compounds did not cause changes of the mechanism of crystal growth which was surface diffusion controlled, as shown by the second order dependence of the rates of mirabilite crystal growth on the relative supersaturation. The excellent fit of the measured rates to a kinetic Langmuir-type model suggested that the activity of the tested inhibitors could be attributed to the adsorption and subsequent reduction of the active crystal growth sites of the seed crystals. In all cases, the inhibitory activity was reduced with

  8. The Effects of Impurities on Protein Crystal Growth and Nucleation: A Preliminary Study

    Science.gov (United States)

    Schall, Constance A.

    1998-01-01

    Kubota and Mullin (1995) devised a simple model to account for the effects of impurities on crystal growth of small inorganic and organic molecules in aqueous solutions. Experimentally, the relative step velocity and crystal growth of these molecules asymptotically approach zero or non-zero values with increasing concentrations of impurities. Alternatively, the step velocity and crystal growth can linearly approach zero as the impurity concentration increases. The Kubota-Mullin model assumes that the impurity exhibits Langmuirian adsorption onto the crystal surface. Decreases in step velocities and subsequent growth rates are related to the fractional coverage (theta) of the crystal surface by adsorbed impurities; theta = Kx / (I +Kx), x = mole fraction of impurity in solution. In the presence of impurities, the relative step velocity, V/Vo, and the relative growth rate of a crystal face, G/Go, are proposed to conform to the following equations: V/Vo approx. = G/Go = 1 - (alpha)(theta). The adsorption of impurity is assumed to be rapid and in quasi-equilibrium with the crystal surface sites available. When the value of alpha, an effectiveness factor, is one the growth will asymptotically approach zero with increasing concentrations of impurity. At values less than one, growth approaches a non-zero value asymptotically. When alpha is much greater than one, there will be a linear relationship between impurity concentration and growth rates. Kubota and Mullin expect alpha to decrease with increasing supersaturation and shrinking size of a two dimensional nucleus. It is expected that impurity effects on protein crystal growth will exhibit behavior similar to that of impurities in small molecule growth. A number of proteins were added to purified chicken egg white lysozyme, the effect on crystal nucleation and growth assessed.

  9. Synthesis, growth, crystal structure, optical and third order nonlinear optical properties of quinolinium derivative single crystal: PNQI

    Science.gov (United States)

    Karthigha, S.; Krishnamoorthi, C.

    2018-03-01

    An organic quinolinium derivative nonlinear optical (NLO) crystal, 1-ethyl-2-[2-(4-nitro-phenyl)-vinyl]-quinolinium iodide (PNQI) was synthesized and successfully grown by slow evaporation solution growth technique. Formation of a crystalline compound was confirmed by single crystal X-ray diffraction. The quinolinium compound PNQI crystallizes in the triclinic crystal system with a centrosymmetric space group of P-1 symmetry. The molecular structure of PNQI was confirmed by 1H NMR and 13C NMR spectral studies. The thermal properties of the crystal have been investigated by thermogravimetric (TG) and differential scanning calorimetry (DSC) studies. The optical characteristics obtained from UV-Vis-NIR spectral data were described and the cut-off wavelength observed at 506 nm. The etching study was performed to analyse the growth features of PNQI single crystal. The third order NLO properties such as nonlinear refractive index (n2), nonlinear absorption coefficient (β) and nonlinear susceptibility (χ (3)) of the crystal were investigated using Z-scan technique at 632.8 nm of Hesbnd Ne laser.

  10. Competitive Growth of - -Crystals in -Nucleated Isotactic Polypropylene under Shear Flow

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.; Mao, Y; Li, Z; Hsiao, B

    2010-01-01

    It has been well established that, although both shear flow and {beta}-nucleating agent could separately induce {beta}-crystals in isotactic polypropylene (iPP) in an efficient manner, their combination in fact depressed the content of {beta}-crystals when compared with quiescently crystallized {beta}-nucleated iPP. In the current study, in-situ synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) measurements were performed to investigate this behavior. The WAXD data obtained were quantitatively analyzed to determine the independent contributions of applied shear flow and added {beta}-nucleating agent in terms of nucleation stage and subsequent {alpha}- and {beta}-crystal growth stage. In the nucleation stage, the addition of {beta}-nucleating agent increased the amount of {beta}-nuclei, while the application of shear flow and the interactions between shear and {beta}-nucleating agent enhanced the amount of {alpha}-nuclei (the amounts of {alpha}- and {beta}-nuclei were in the same order of magnitude). As a result, in the initial crystallization, {alpha}- and {beta}-crystals grew competitively, causing simultaneously increments of {alpha}- and {beta}-crystals. However, in the growth stage, the growth rate of {beta}-crystals was faster than that of {alpha}-crystals where the epitaxial growth of {beta}-crystals on {alpha}-crystals also occurred (due to more favorable isothermal crystallization temperature for {beta}-crystal growth). Consequently, the content of {beta}-crystals became dominant in the limited growth space; however, it was still less than that formed from the quiescent isothermal crystallization of {beta}-nucleated iPP. As the shear rate increased, more shear-induced {alpha}-nuclei were formed, further decreasing the amount of {beta}-crystals. Nevertheless, when shear and {beta}-nucleating agent coexisted, {beta}-crystals emerged earlier than {alpha}-crystals. The SAXS results indicated that the combination of shear

  11. Boron Arsenide and Boron Phosphide for High Temperature and Luminescent Devices. [semiconductor devices - crystal growth/crystal structure

    Science.gov (United States)

    Chu, T. L.

    1975-01-01

    The crystal growth of boron arsenide and boron phosphide in the form of bulk crystals and epitaxial layers on suitable substrates is discussed. The physical, chemical, and electrical properties of the crystals and epitaxial layers are examined. Bulk crystals of boron arsenide were prepared by the chemical transport technique, and their carrier concentration and Hall mobility were measured. The growth of boron arsenide crystals from high temperature solutions was attempted without success. Bulk crystals of boron phosphide were also prepared by chemical transport and solution growth techniques. Techniques required for the fabrication of boron phosphide devices such as junction shaping, diffusion, and contact formation were investigated. Alloying techniques were developed for the formation of low-resistance ohmic contacts to boron phosphide. Four types of boron phosphide devices were fabricated: (1) metal-insulator-boron phosphide structures, (2) Schottky barriers; (3) boron phosphide-silicon carbide heterojunctions; and (4) p-n homojunctions. Easily visible red electroluminescence was observed from both epitaxial and solution grown p-n junctions.

  12. Crystal Growth Inhibitors for the Prevention of L-Cystine Kidney Stones Through Molecular Design

    Energy Technology Data Exchange (ETDEWEB)

    Rimer, Jeffrey D.; An, Zhihua; Zhu, Zina; Lee, Michael H.; Goldfarb, David S.; Wesson, Jeffrey A.; Ward, Michael D. (NY Univ.); (MCW)

    2010-11-12

    Crystallization of L-cystine is a critical step in the pathogenesis of cystine kidney stones. Treatments for this disease are somewhat effective but often lead to adverse side effects. Real-time in situ atomic force microscopy (AFM) reveals that L-cystine dimethylester (L-CDME) and L-cystine methylester (L-CME) dramatically reduce the growth velocity of the six symmetry-equivalent {l_brace}100{r_brace} steps because of specific binding at the crystal surface, which frustrates the attachment of L-cystine molecules. L-CDME and L-CME produce L-cystine crystals with different habits that reveal distinct binding modes at the crystal surfaces. The AFM observations are mirrored by reduced crystal yield and crystal size in the presence of L-CDME and L-CME, collectively suggesting a new pathway to the prevention of L-cystine stones by rational design of crystal growth inhibitors.

  13. On melt solutions for the growth of CaTiO3 crystals

    Science.gov (United States)

    Klimm, Detlef; Schmidt, Max; Wolff, Nora; Guguschev, Christo; Ganschow, Steffen

    2018-03-01

    When calcium titanate crystals are grown from stoichiometric melts, they crystallize in the cubic perovskite structure. Upon cooling to room temperature they undergo subsequent phase transitions to tetragonal and orthorhombic modifications. These phase transitions are disruptive and result in severely damaged crystals. This paper presents differential thermal analysis data for several prospective solvents, with the aim to identify a system offering the possibility to perform crystal growth of undistorted CaTiO3 crystals by crystallizing them significantly below the melting point directly in the low temperature modification. From mixtures CaF2:TiO2:CaTiO3 = 3:1:1 (molar ratio) the growth of undistorted, at least millimeter-sized CaTiO3 crystals is possible.

  14. The effect of tailor-made additives on crystal growth of methyl paraben: Experiments and modelling

    Science.gov (United States)

    Cai, Zhihui; Liu, Yong; Song, Yang; Guan, Guoqiang; Jiang, Yanbin

    2017-03-01

    In this study, methyl paraben (MP) was selected as the model component, and acetaminophen (APAP), p-methyl acetanilide (PMAA) and acetanilide (ACET), which share the similar molecular structure as MP, were selected as the three tailor-made additives to study the effect of tailor-made additives on the crystal growth of MP. HPLC results indicated that the MP crystals induced by the three additives contained MP only. Photographs of the single crystals prepared indicated that the morphology of the MP crystals was greatly changed by the additives, but PXRD and single crystal diffraction results illustrated that the MP crystals were the same polymorph only with different crystal habits, and no new crystal form was found compared with other references. To investigate the effect of the additives on the crystal growth, the interaction between additives and facets was discussed in detail using the DFT methods and MD simulations. The results showed that APAP, PMAA and ACET would be selectively adsorbed on the growth surfaces of the crystal facets, which induced the change in MP crystal habits.

  15. Crystal growth and properties of novel organic nonlinear optical crystals of 4-Nitrophenol urea

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, M. Krishna, E-mail: krishnamohan.m@ktr.srmuniv.ac.in; Ponnusamy, S.; Muthamizhchelvan, C.

    2017-07-01

    Single crystals of 4-Nitrophenol urea have been grown from water using slow evaporation technique at constant temperature, with the vision to improve the properties of the crystals. The unit cell parameters of the grown crystals were determined by single crystal and powder X-Ray diffraction. FTIR studies reveals the presence of different vibrational bands. The Optical studies confirmed that the crystal is transparent up to 360 nm .TGA and DSC studies were carried out to understand the thermal behavior of crystals. The SHG studies show the suitability of the crystals for NLO applications. The etching studies were carried out to study the behavior of the crystals under different conditions.These studies reveal that the crystals of 4-Nitrophenol urea are suitable for device applications. - Highlights: • 4-Nitrophenol urea crystals of dimensions 14 mm × 1 mm were grown. • UV–Visible studies indicate the crystal is transparent in the region of 370–800 nm. • Thermal studies show the crystal starts decomposing at 170 °C. • SHG studies indicate that the crystals have NLO efficiency 3.5 times that of KDP.

  16. Experimental and numerical study on growth of high-quality ZnO single-crystal microtubes by optical vapor supersaturated precipitation method

    Science.gov (United States)

    Wang, Qiang; Yan, Yinzhou; Zeng, Yong; Jiang, Yijian

    2017-06-01

    In this work, high-quality free-standing ZnO single-crystal microtubes with hexagonal cross-section were fabricated by an optical image furnace. Optical vapor supersaturated precipitation (OVSP) and axial photo-thermal-decomposition were proposed to interpret the microrods growth and microtubes formation, respectively. The maximum dimensions of the grown microtube were 5 mm in length, 100 μm in diameter and 1 μm in facet wall thickness. In our previous work, a new room-temperature photoluminescence (PL) peak ( 392 nm) of ZnO microtubes was attributed to VZn-related donor-acceptor-pairs (DAP) transition. This work further confirmed the VZn-related acceptors widely existing during ZnO microrods/ microtubes growth by OVSP. The effects of major growth parameters (e.g. lamp power, filament geometry and growth platform shape) on temperature field at the growth platform of precursor rod were studied by a finite element model as well. The lamp power of 65% (1500 W), thick single-filament and appropriate conical growth platform were optimized for a uniform temperature field to achieve consistent finish quality of microtubes and prevent twin-microtubes formation. This work would be beneficial for batch growth of the novel ZnO microtubes/microrods with high quality for a variety of applications.

  17. Crystal Growth and Scintillation Properties of Eu2+ doped Cs4CaI6 and Cs4SrI6

    Science.gov (United States)

    Stand, L.; Zhuravleva, M.; Chakoumakos, B.; Johnson, J.; Loyd, M.; Wu, Y.; Koschan, M.; Melcher, C. L.

    2018-03-01

    In this work we present the crystal growth and scintillation properties of two new ternarymetal halide scintillators activated with divalent europium, Cs4CaI6 and Cs4SrI6. Single crystals of each compound were grown in evacuated quartz ampoules via the vertical Bridgman technique using a two-zone transparent furnace. Single crystal X-ray diffraction experiments showed that both crystals have a trigonal (R-3c) structure, with a density of 3.99 g/cm3 and 4.03 g/cm3. The radioluminescence and photoluminescence measurements showed typical luminescence properties due to the 5d-4f radiative transitions in Eu2+. At this early stage of development Cs4SrI6:Eu and Cs4CaI6:Eu have shown very promising scintillation properties, with light yields and energy resolutions of 62,300 ph/MeV and 3.3%, and 51,800 photons/MeV and 3.6% at 662 keV, respectively.

  18. Modeling the effect of crystal and crucible rotation on the interface shape in Czochralski growth of piezoelectric langatate crystals

    Science.gov (United States)

    Stelian, C.; Nehari, A.; Lasloudji, I.; Lebbou, K.; Dumortier, M.; Cabane, H.; Duffar, T.

    2017-10-01

    Single La3Ga5.5Ta0.5O14 (LGT) crystals have been grown by using the Czochralski technique with inductive heating. Some ingots exhibit imperfections such as cracks, dislocations and striations. Numerical modeling is applied to investigate the factors affecting the shape of the crystal-melt interface during the crystallization of ingots having 3 cm in diameter. It was found that the conical shape of the interface depends essentially on the internal radiative exchanges in the semi-transparent LGT crystal. Numerical results are compared to experimental visualization of the growth interface, showing a good agreement. The effect of the forced convection produced by the crystal and crucible rotation is numerically investigated at various rotation rates. Increasing the crystal rotation rate up to 50 rpm has a significant flattening effect on the interface shape. Applying only crucible rotation enhances the downward flow underneath the crystal, leading to an increased interface curvature. Counter rotation between the crystal and the crucible results in a distorted shape of the interface.

  19. Stacking fault growth of FCC crystal: The Monte-Carlo simulation approach

    International Nuclear Information System (INIS)

    Jian Jianmin; Ming Naiben

    1988-03-01

    The Monte-Carlo method has been used to simulate the growth of the FCC (111) crystal surface, on which is presented the outcrop of a stacking fault. The comparison of the growth rates has been made between the stacking fault containing surface and the perfect surface. The successive growth stages have been simulated. It is concluded that the outcrop of stacking fault on the crystal surface can act as a self-perpetuating step generating source. (author). 7 refs, 3 figs

  20. A framework for multi-scale simulation of crystal growth in the presence of polymers.

    Science.gov (United States)

    Mandal, Taraknath; Huang, Wenjun; Mecca, Jodi M; Getchell, Ashley; Porter, William W; Larson, Ronald G

    2017-03-01

    We present a multi-scale simulation method for modeling crystal growth in the presence of polymer excipients. The method includes a coarse-grained (CG) model for small molecules of known crystal structure whose force field is obtained using structural properties from atomistic simulations. This CG model is capable of stabilizing the molecular crystal structure and capturing the crystal growth from the melt for a wide range of small organic molecules, as demonstrated by application of our method to the molecules isoniazid, urea, sulfamethoxazole, prilocaine, oxcarbazepine, and phenytoin. This CG model can also be used to study the effect of additives, such as polymers, on the inhibition of crystal growth by polymers, as exemplified by our simulation of suppression of the rate of crystal growth of phenytoin, an active pharmaceutical ingredient (API), by a cellulose excipient, functionalized with acetate (Ac), hydroxy-propyl (Hp) and succinate (Su) groups. We show that the efficacy of the cellulosic polymers in slowing crystal growth of small molecules strongly depends on the functional group substitution on the cellulose backbone, with the acetate substituent group slowing crystal growth more than does the deprotonated succinate group, which we confirm by experimental drug supersaturation studies.

  1. A Study of Biomolecules as Growth Modifiers of Calcium Oxalate Crystals

    Science.gov (United States)

    Kwak, Junha John

    Crystallization processes are ubiquitous in nature, science, and technology. Controlling crystal growth is pivotal in many industries as material properties and functions can be tailored by tuning crystal habits (e.g. size, shape, phase). In biomineralization, organisms exert excellent control over bottom-up synthesis and assembly of inorganic-organic structures (e.g. bones, teeth, exoskeletons). This is made possible by growth modifiers that range from small molecules to macromolecules, such as proteins. Molecular recognition of the mineral phase allows proteins to function as nucleation templates, matrices, and growth inhibitors or promoters. We are interested in taking a biomimetic approach to control crystallization via biomolecular growth modifiers. We investigated calcium oxalate monohydrate (COM), found in plants and kidney stones, as a model system of crystallization. We studied the effects of four common proteins on COM crystallization: bovine serum albumin (BSA), transferrin, lactoferrin, and lysozyme. Through kinetic studies of COM crystallization, we classified BSA and lysozyme as COM growth inhibitor and promoter respectively. Their inhibition and promotion effects were also evident in the macroscopic crystal habit. Through adsorption and microscopy experiments, we showed that BSA exhibits binding specificity for the apical surfaces of macroscopic COM crystals. Lysozyme, on the other, functions via a non-binding mechanism at the surface to accelerate the growth of the apical surfaces. We also synthesized and studied peptides derived from the protein primary sequences to identify putative domains responsible for these inhibition and promotion effects. Collectively, our study of physiologically relevant biomolecules suggests potential roles of COM modifiers in pathological crystallization and helps to develop guidelines for rational design of biomolecular growth modifiers for applications in crystal engineering.

  2. ENERGY STAR Certified Furnaces

    Data.gov (United States)

    U.S. Environmental Protection Agency — Certified models meet all ENERGY STAR requirements as listed in the Version 4.1 ENERGY STAR Program Requirements for Furnaces that are effective as of February 1,...

  3. Crystal Growth and Fluid Mechanics Problems in Directional Solidification

    Science.gov (United States)

    Tanveer, Saleh A.; Baker, Gregory R.; Foster, Michael R.

    2001-01-01

    Our work in directional solidification has been in the following areas: (1) Dynamics of dendrites including rigorous mathematical analysis of the resulting equations; (2) Examination of the near-structurally unstable features of the mathematically related Hele-Shaw dynamics; (3) Numerical studies of steady temperature distribution in a vertical Bridgman device; (4) Numerical study of transient effects in a vertical Bridgman device; (5) Asymptotic treatment of quasi-steady operation of a vertical Bridgman furnace for large Rayleigh numbers and small Biot number in 3D; and (6) Understanding of Mullins-Sererka transition in a Bridgman device with fluid dynamics is accounted for.

  4. Single-crystal growth of ceria-based materials

    International Nuclear Information System (INIS)

    Ulbrich, Gregor

    2015-01-01

    In this work it could be shown that Skull-Melting is a suitable method for growing ceria single crystals. Twenty different ceria-based single crystals could be manufactured. It was possible to dope ceria single crystals with Gd, Sm, Y, Zr, Ti, Ta, and Pr in different concentrations. Also co-doping with the named metals was realized. However, there remain some problems for growing ceria-based single crystals by Skull-Melting. As ignition metal zirconium was used because no ceria-based material works well. For that reason all single crystals show small zirconium contamination. Another problem is the formation of oxygen by the heat-induced reduction of ceria during the melting process. Because of that the skull of sintered material is often destroyed by gas pressure. This problem had to be solved individually for every single crystal. The obtained single crystals were characterized using different methods. To ensure the single crystal character the y were examined by Laue diffraction. All manufactured crystals are single crystals. Also powder diffraction patterns of the milled and oxidized samples were measured. For the determination of symmetry and metric the structural parameters were analyzed by the Rietveld method. All synthesized materials crystallize in space group Fm-3m known from calcium fluoride. The cubic lattice parameter a was determined for all crystals. In the case of series with different cerium and zirconium concentrations a linear correlation between cerium content and cubic lattice parameter was detected. The elemental composition was determined by WDX. All crystals show a homogeneous elemental distribution. The oxygen content was calculated because the WDX method isn't useful for determination.

  5. Insights into crystal growth rates from a study of orbicular granitoids from western Australia

    Science.gov (United States)

    Zhang, J.; Lee, C. T.

    2017-12-01

    The purpose of this study is to develop new tools for constraining crystal growth rate in geologic systems. Of interest is the growth of crystals in magmatic systems because crystallization changes the rheology of a magma as well as provides surfaces on which bubbles can nucleate. To explore crystal growth in more detail, we conducted a case study of orbicular granitoids from western Australia. The orbicules occur as spheroids dispersed in a granitic matrix. Most orbicules have at least two to three concentric bands, composed of elongate and radially oriented hornblende surrounded by interstitial plagioclase. We show that mineral modes and hence bulk composition at the scale of the band is homogeneous from rim to core. Crystal number density decreases and crystal size increases from rim to core. These observations suggest that the orbicules crystallized rapidly from rim to core. We hypothesize that the orbicules are blobs of hot dioritic liquid injected into a cold granitic magma and subsequently cooled and solidified. Crystals stop growing when the mass transport rate tends to zero due to the low temperature. We estimated cooling timescales based on conductive cooling models, constraining crystal growth rates to be 10-6 to 10-5 m/s. We also show that the oscillatory banding is controlled by disequilibrium crystallization, wherein hornblende preferentially crystallizes, resulting in the diffusive growth of a chemical boundary layer enriched in plagioclase component, which in turns results in crystallization of plagioclase. We show that the correlation between the width of each crystallization couplet (band) with distance from orbicule rim is linear, with the slope corresponding to the square root of the ratio between chemical diffusivity in the growth medium and thermal diffusivity. We estimate chemical diffusivity of 2*10-7 m2/s, which is remarkably fast for silicate liquids but reasonable for diffusion in hot aqueous fluids, suggesting that crystallization

  6. Surface growth mechanisms and structural faulting in the growth of large single and spherulitic titanosilicate ETS-4 crystals

    Science.gov (United States)

    Miraglia, Peter Q.; Yilmaz, Bilge; Warzywoda, Juliusz; Sacco, Albert

    2004-10-01

    Morphological, surface and crystallographic analyses of titanosilicate ETS-4 products, with diverse habits ranging from spherulitic particles composed of submicron crystallites to large single crystals, are presented. Pole figures revealed that crystal surfaces with a-, b- and c- axes corresponded to , and directions, respectively. Thus, technologically important 8-membered ring pores and titania chains in ETS-4 run along the b-axis of single crystals and terminate at the smallest crystal face. Height of the spiral growth steps observed on {1 0 0} and {0 0 1} surfaces corresponded to the interplanar spacings associated with their crystallographic orientation, and is equivalent to the thickness of building units that form the ETS-4 framework. Data suggest that the more viscous synthesis mixtures, with a large driving force for growth, increased the two- and three-dimensional nucleation, while limiting the transport of nutrients to the growth surface. These conditions increase the tendency for stacking fault formation on {1 0 0} surfaces and small angle branching, which eventually results in spherulitic growth. The growth of high quality ETS-4 single crystals (from less viscous synthesis mixtures) occurred at lower surface nucleation rates. Data suggest that these high quality, large crystals grew due to one-dimensional nucleation at spiral hillocks, and indicate that under these conditions un-faulted growth is preferred.

  7. Growth and microtopographic study of CuInSe{sub 2} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Sanjaysinh M.; Chaki, Sunil, E-mail: sunilchaki@yahoo.co.in; Deshpande, M. P. [Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Gujarat - 388120 (India); Tailor, J. P. [Applied Physics Department, S.V.N.I.T., Surat, Gujarat - 395007 (India)

    2016-05-23

    The CuInSe{sub 2} single crystals were grown by chemical vapour transport (CVT) technique using iodine as transporting agent. The elemental composition of the as-grown CuInSe{sub 2} single crystals was determined by energy dispersive analysis of X-ray (EDAX). The unit cell crystal structure and lattice parameters were determined by X-ray diffraction (XRD) technique. The surface microtopographic study of the as-grown CuInSe{sub 2} single crystals surfaces were done to study the defects, growth mechanism, etc. of the CVT grown crystals.

  8. Inhibition of ice crystal growth in ice cream mix by gelatin hydrolysate.

    Science.gov (United States)

    Damodaran, Srinivasan

    2007-12-26

    The inhibition of ice crystal growth in ice cream mix by gelatin hydrolysate produced by papain action was studied. The ice crystal growth was monitored by thermal cycling between -14 and -12 degrees C at a rate of one cycle per 3 min. It is shown that the hydrolysate fraction containing peptides in the molecular weight range of about 2000-5000 Da exhibited the highest inhibitory activity on ice crystal growth in ice cream mix, whereas fractions containing peptides greater than 7000 Da did not inhibit ice crystal growth. The size distribution of gelatin peptides formed in the hydrolysate was influenced by the pH of hydrolysis. The optimum hydrolysis conditions for producing peptides with maximum ice crystal growth inhibitory activity was pH 7 at 37 degrees C for 10 min at a papain to gelatin ratio of 1:100. However, this may depend on the type and source of gelatin. The possible mechanism of ice crystal growth inhibition by peptides from gelatin is discussed. Molecular modeling of model gelatin peptides revealed that they form an oxygen triad plane at the C-terminus with oxygen-oxygen distances similar to those found in ice nuclei. Binding of this oxygen triad plane to the prism face of ice nuclei via hydrogen bonding appears to be the mechanism by which gelatin hydrolysate might be inhibiting ice crystal growth in ice cream mix.

  9. Ultratough CVD single crystal diamond and three dimensional growth thereof

    Science.gov (United States)

    Hemley, Russell J [Washington, DC; Mao, Ho-kwang [Washington, DC; Yan, Chih-shiue [Washington, DC

    2009-09-29

    The invention relates to a single-crystal diamond grown by microwave plasma chemical vapor deposition that has a toughness of at least about 30 MPa m.sup.1/2. The invention also relates to a method of producing a single-crystal diamond with a toughness of at least about 30 MPa m.sup.1/2. The invention further relates to a process for producing a single crystal CVD diamond in three dimensions on a single crystal diamond substrate.

  10. Uniaxial crystal growth in thin film by utilizing supercooled state of mesogenic phthalocyanine

    Science.gov (United States)

    Fiderana Ramananarivo, Mihary; Higashi, Takuya; Ohmori, Masashi; Sudoh, Koichi; Fujii, Akihiko; Ozaki, Masanori

    2016-06-01

    A method of uniaxial crystal growth in wet-processed thin films of the mesogenic phthalocyanine 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) is proposed. It consists of applying geometrically linear thermal stimulation to a supercooled state of liquid crystalline C6PcH2. The thin film showed highly ordered molecular stacking structure and uniaxial alignment over a macroscopic scale. An explanation of the crystal growth mechanism is suggested by taking into account the temperature range of crystal growth and the hysteresis property of C6PcH2 in the phase transition.

  11. VO2 (A): Reinvestigation of crystal structure, phase transition and crystal growth mechanisms

    Science.gov (United States)

    Rao Popuri, Srinivasa; Artemenko, Alla; Labrugere, Christine; Miclau, Marinela; Villesuzanne, Antoine; Pollet, Michaël

    2014-05-01

    Well crystallized VO2 (A) microrods were grown via a single step hydrothermal reaction in the presence of V2O5 and oxalic acid. With the advantage of high crystalline samples, we propose P4/ncc as an appropriate space group at room temperature. From morphological studies, we found that the oriented attachment and layer by layer growth mechanisms are responsible for the formation of VO2 (A) micro rods. The structural and electronic transitions in VO2 (A) are strongly first order in nature, and a marked difference between the structural transition temperatures and electronic transitions temperature was evidenced. The reversible intra- (LTP-A to HTP-A) and irreversible inter- (HTP-A to VO2 (M1)) structural phase transformations were studied by in-situ powder X-ray diffraction. Attempts to increase the size of the VO2 (A) microrods are presented and the possible formation steps for the flower-like morphologies of VO2 (M1) are described.

  12. Introducing uncertainty analysis of nucleation and crystal growth models in Process Analytical Technology (PAT) system design of crystallization processes.

    Science.gov (United States)

    Samad, Noor Asma Fazli Abdul; Sin, Gürkan; Gernaey, Krist V; Gani, Rafiqul

    2013-11-01

    This paper presents the application of uncertainty and sensitivity analysis as part of a systematic model-based process monitoring and control (PAT) system design framework for crystallization processes. For the uncertainty analysis, the Monte Carlo procedure is used to propagate input uncertainty, while for sensitivity analysis, global methods including the standardized regression coefficients (SRC) and Morris screening are used to identify the most significant parameters. The potassium dihydrogen phosphate (KDP) crystallization process is used as a case study, both in open-loop and closed-loop operation. In the uncertainty analysis, the impact on the predicted output of uncertain parameters related to the nucleation and the crystal growth model has been investigated for both a one- and two-dimensional crystal size distribution (CSD). The open-loop results show that the input uncertainties lead to significant uncertainties on the CSD, with appearance of a secondary peak due to secondary nucleation for both cases. The sensitivity analysis indicated that the most important parameters affecting the CSDs are nucleation order and growth order constants. In the proposed PAT system design (closed-loop), the target CSD variability was successfully reduced compared to the open-loop case, also when considering uncertainty in nucleation and crystal growth model parameters. The latter forms a strong indication of the robustness of the proposed PAT system design in achieving the target CSD and encourages its transfer to full-scale implementation. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Supersaturation Control using Analytical Crystal Size Distribution Estimator for Temperature Dependent in Nucleation and Crystal Growth Phenomena

    Science.gov (United States)

    Zahari, Zakirah Mohd; Zubaidah Adnan, Siti; Kanthasamy, Ramesh; Saleh, Suriyati; Samad, Noor Asma Fazli Abdul

    2018-03-01

    The specification of the crystal product is usually given in terms of crystal size distribution (CSD). To this end, optimal cooling strategy is necessary to achieve the CSD. The direct design control involving analytical CSD estimator is one of the approaches that can be used to generate the set-point. However, the effects of temperature on the crystal growth rate are neglected in the estimator. Thus, the temperature dependence on the crystal growth rate needs to be considered in order to provide an accurate set-point. The objective of this work is to extend the analytical CSD estimator where Arrhenius expression is employed to cover the effects of temperature on the growth rate. The application of this work is demonstrated through a potassium sulphate crystallisation process. Based on specified target CSD, the extended estimator is capable of generating the required set-point where a proposed controller successfully maintained the operation at the set-point to achieve the target CSD. Comparison with other cooling strategies shows a reduction up to 18.2% of the total number of undesirable crystals generated from secondary nucleation using linear cooling strategy is achieved.

  14. GROWTH RATE DISTRIBUTION OF BORAX SINGLE CRYSTALS ON THE (001 FACE UNDER VARIOUS FLOW RATES

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available The growth rates of borax single crystals from aqueous solutions at various flow rates in the (001 direction were measured using in situ cell method. From the growth rate data obtained, the growth rate distribution of borax crystals was investigated using Minitab Software and SPSS Software at relative supersaturation of 0807 and temperature of 25 °C. The result shows that normal, gamma, and log-normal distribution give a reasonably good fit to GRD. However, there is no correlation between growth rate distribution and flow rate of solution.   Keywords: growth rate dispersion (GRD, borax, flow rate

  15. On the growth of calcium tartrate tetrahydrate single crystals

    Indian Academy of Sciences (India)

    Unknown

    menon, especially those involved in the gel technique. With an aim of controlling nucleation and improving the size, in the present study, we have grown pure calcium tartrate tetrahydrate single crystals using calcium formate mixed with formic acid as the supernatant solution. The grown crystals have been characterized by ...

  16. Crystal growth and morphology of calcium oxalates and carbonates

    NARCIS (Netherlands)

    Heijnen, W.M.M.

    1986-01-01

    The main purpose of the research described in this thesis is to establish a relationship between the crystal structure and morphology of calcium oxalate and calcium carbonate crystals grown from aqueous solutions. Starting point is the PBC (Periodic Bond Chain) theory formulated by Hartman and

  17. Crystal growth and structural analysis of zirconium sulphoselenide ...

    Indian Academy of Sciences (India)

    Wintec

    The effect of sulphur propor- tion on the lattice parameter, unit cell ... Hall effect measure- ments were carried out on grown crystals at room temperature. The negative value of Hall coefficient implies that these crystals are n-type in nature. The conductivity is found to ... Resistivity, Hall coefficient and thermo electric power ...

  18. Control of nucleation and crystal growth of a silicate apatitic phase in a glassy matrix

    International Nuclear Information System (INIS)

    Ligny, D.; Caurant, D.; Bardez, I.; Dussossoy, J.L.; Loiseau, P.; Neuville, D.R.

    2004-01-01

    Nucleation and growth of crystal in an oxide glass was studied in a Si B Al Zr Nd Ca Na O system. The nucleation and growth process were monitored by thermal analysis and isothermal experiments. The effect of the network modifier was studied. Therefore for a Ca rich sample the crystallization is homogeneous in the bulk showing a slow increase of crystallinity as temperature increases. On the other hand, a Na rich sample undergoes several crystallization processes in the bulk or from the surface, leading to bigger crystals. The activation energy of the viscous flow and the glass transition are of same magnitude when that of crystallization is a lot smaller. Early diffusion of element is done with a mechanism different than the configurational rearrangements of the liquid sate. The global density and small size of the crystals within the Ca rich matrix confirmed that it would be a profitable waste form for minor actinides. (authors)

  19. Existence of thickness threshold for crystal growth rate of ascorbic acid from its thin solution film

    Science.gov (United States)

    Yamazaki, Yoshihiro; Yoshino, Hiroki; Kikuchi, Mitsunobu; Kashiwase, Sakiko

    2017-06-01

    Growth rate of ascorbic acid crystal domains from its aqueous solution film depends on the film thickness. Existence of a thickness threshold is experimentally confirmed below which growth rate becomes quite low and is considered to almost stop. This threshold is one of the essential factors for the dynamical transition between uniform and rhythmic growth modes.

  20. Growth of large aluminum nitride single crystals with thermal-gradient control

    Science.gov (United States)

    Bondokov, Robert T; Rao, Shailaja P; Gibb, Shawn Robert; Schowalter, Leo J

    2015-05-12

    In various embodiments, non-zero thermal gradients are formed within a growth chamber both substantially parallel and substantially perpendicular to the growth direction during formation of semiconductor crystals, where the ratio of the two thermal gradients (parallel to perpendicular) is less than 10, by, e.g., arrangement of thermal shields outside of the growth chamber.

  1. Crystal growth, optical properties, and laser operation of Yb3+-doped NYW single crystal

    Science.gov (United States)

    Cheng, Y.; Xu, X. D.; Yang, X. B.; Xin, Z.; Cao, D. H.; Xu, J.

    2009-11-01

    Laser crystal Yb3+-doped NaY(WO4)2 (Yb:NYW) with excellent quality has been grown by Czochralski technique. The rocking curves from (400) plane of as-grown Yb:NYW crystal was measured and the full-width value at half-maximum was 19.92″. The effective segregation coefficients were measured by the X-ray fluorescence method. The polarized absorption spectra and the fluorescence spectra of Yb:NYW crystal were measured at room temperature. The fluorescence decay lifetime of Yb3+ ion in NYW crystal has been investigated. The spectroscopic parameters of Yb:NYW crystal are calculated and compared with those of Yb:YAG crystal. A continuous wave output power of 3.06 W at 1031 nm was obtained with a slope efficiency of 42% by use of diode pumping.

  2. Controlling single and few-layer graphene crystals growth in a solid carbon source based chemical vapor deposition

    International Nuclear Information System (INIS)

    Papon, Remi; Sharma, Subash; Shinde, Sachin M.; Vishwakarma, Riteshkumar; Tanemura, Masaki; Kalita, Golap

    2014-01-01

    Here, we reveal the growth process of single and few-layer graphene crystals in the solid carbon source based chemical vapor deposition (CVD) technique. Nucleation and growth of graphene crystals on a polycrystalline Cu foil are significantly affected by the injection of carbon atoms with pyrolysis rate of the carbon source. We observe micron length ribbons like growth front as well as saturated growth edges of graphene crystals depending on growth conditions. Controlling the pyrolysis rate of carbon source, monolayer and few-layer crystals and corresponding continuous films are obtained. In a controlled process, we observed growth of large monolayer graphene crystals, which interconnect and merge together to form a continuous film. On the other hand, adlayer growth is observed with an increased pyrolysis rate, resulting few-layer graphene crystal structure and merged continuous film. The understanding of monolayer and few-layer crystals growth in the developed CVD process can be significant to grow graphene with controlled layer numbers.

  3. Studies on growth, crystal structure and characterization of novel organic nicotinium trifluoroacetate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dhanaraj, P.V. [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110 (India); Rajesh, N.P., E-mail: rajeshnp@hotmail.com [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam 603 110 (India); Sundar, J. Kalyana; Natarajan, S. [Department of Physics, Madurai Kamaraj University, Madurai 625 021 (India); Vinitha, G. [Department of Physics, Crescent Engineering College, Chennai 600 048 (India)

    2011-09-15

    Highlights: {yields} Good quality crystals of nicotinium trifluoroacetate in monoclinic system were grown for first time. {yields} Nicotinium trifluoroacetate crystal exhibits third order nonlinear optical properties. {yields} The optical spectrum of nicotinium trifluoroacetate crystal reveals the wide transmission in the entire range with cutoff wavelength at 286 nm. {yields} Nicotinium trifluoroacetate is a low dielectric constant material. - Abstract: An organic material, nicotinium trifluoroacetate (NTF) was synthesized and single crystals in monoclinic system were grown from aqueous solution for the first time. Its solubility and metastable zone width were estimated. The crystal structure of NTF was analyzed to reveal the molecular arrangements and the formation of hydrogen bonds in the crystal. High-resolution X-ray diffraction rocking curve measurements were performed to analyze the structural perfection of the grown crystals. Functional groups in NTF were identified by Fourier transform infrared spectral analysis. Thermal behaviour and stability of NTF were studied by thermogravimetric and differential thermal analysis and differential scanning calorimetry. Mechanical and dielectric properties of NTF crystals were analyzed. Optical studies reveal that NTF crystals are transparent in the wavelength range 286-1100 nm. The third order nonlinear optical parameters of NTF were derived by the Z-scan technique.

  4. Growth, crystal structure and characterization of a nonlinear optical crystal: Deuterated L-arginine trifluoroacetate

    Energy Technology Data Exchange (ETDEWEB)

    Sun, G.H., E-mail: sgh2@mail.sdu.edu.cn [State Key Lab of Crystal Materials and Institute of Crystal Materials, Shandong, University, Jinan, 250100 (China); Zhang, G.H.; Sun, Z.H.; Wang, X.Q. [State Key Lab of Crystal Materials and Institute of Crystal Materials, Shandong, University, Jinan, 250100 (China); Xu, D., E-mail: xdoffice@sdu.edu.cn [State Key Lab of Crystal Materials and Institute of Crystal Materials, Shandong, University, Jinan, 250100 (China)

    2011-05-16

    Research highlights: {yields} Bulk crystals of deuterated L-arginine trifluoroacetate (DLATF) have been grown successfully. {yields} The distances between the N-D covalent bonds in DLATF crystal is about 0.4% shorter than N-H bonds in LATF crystal, which agrees with other reports. {yields} Due to deuterating, the degree of transmission and the transparent region of the crystal have been improved observably. {yields} Furthermore, the crystal possesses relatively large specific heat and higher laser damage threshold. - Abstract: In order to reduce the absorption of L-arginine trifluoroacetate (LATF) in near-infrared region, deuterated LATF (DLATF) crystals have been synthesized and grown successfully. The grown crystals were characterized by the single crystal and powder X-ray diffraction methods, Fourier transform infrared and Raman spectra. DLATF belongs to monoclinic space system, space group P2{sub 1}, with unit cell parameters: a = 10.547(6), b = 5.696(3), c = 10.825(6) A, {beta} = 106.747(10){sup o}, V = 622.8(6) A{sup 3} and Z = 2. Thermogravimetric (TG) and differential thermal analysis (DTA) studies were carried out to characterize its thermal behaviors. The specific heat has been investigated in the temperature range of 293-453 K. Optical transmission spectrum and second harmonic generation were investigated to study its optical properties. The laser-induced damage threshold measurement revealed that the crystal has a higher damage threshold than that of LATF.

  5. A Low-Cost System Based on Image Analysis for Monitoring the Crystal Growth Process

    Directory of Open Access Journals (Sweden)

    Fabrício Venâncio

    2017-05-01

    Full Text Available Many techniques are used to monitor one or more of the phenomena involved in the crystallization process. One of the challenges in crystal growth monitoring is finding techniques that allow direct interpretation of the data. The present study used a low-cost system, composed of a commercial webcam and a simple white LED (Light Emitting Diode illuminator, to follow the calcium carbonate crystal growth process. The experiments were followed with focused beam reflectance measurement (FBRM, a common technique for obtaining information about the formation and growth of crystals. The images obtained in real time were treated with the red, blue, and green (RGB system. The results showed a qualitative response of the system to crystal formation and growth processes, as there was an observed decrease in the signal as the growth process occurred. Control of the crystal growth was managed by increasing the viscosity of the test solution with the addition of monoethylene glycol (MEG at 30% and 70% in a mass to mass relationship, providing different profiles of the RGB average curves. The decrease in the average RGB value became slower as the concentration of MEG was increased; this reflected a lag in the growth process that was proven by the FBRM.

  6. Crystal growth, characterization and theoretical studies of 4-aminopyridinium picrate

    Science.gov (United States)

    Aditya Prasad, A.; Muthu, K.; Rajasekar, M.; Meenatchi, V.; Meenakshisundaram, S. P.

    2015-01-01

    Single crystals of 4-aminopyridinium picrate (APP) were grown by slow evaporation of a mixed solvent system methanol-acetone (1:1, v/v) containing equimolar quantities of 4-aminopyridine and picric acid. Structure is elucidated by single crystal XRD analysis and the crystal belongs to monoclinic system with four molecules in the unit cell (space group P21/c) and the cell parameter values are, a = 8.513 Å (±0.015), b = 11.33 Å (±0.02), c = 14.33 Å (±0.03) and β = 104.15° (±0.019), V = 1340 A3 (±6) with refined R factors R1 = 0.0053 and wR2 = 0.0126. The electron density mapping is interpreted to find coordinates for each atom in the crystallized molecules. The various functional groups present in the molecule are confirmed by FT-IR analysis. UV-visible spectral analysis was used to determine the band gap energy of 4-aminopyridinium picrate. Powder X-ray diffraction pattern reveals the crystallinity of the as-grown crystal and it closely resembles the simulated XRD from the single crystal XRD analysis. Scanning electron microscopy reveals the surface morphology of the grown crystal. Optimized geometry is derived by Hartree-Fock theory calculations and the first-order molecular hyperpolarizability (β), theoretically calculated bond length, bond angles and excited state energy from theoretical UV-vis spectrum were estimated.

  7. Acousto-optical phonon excitation in piezoelectric wurtzite slabs and crystal growth orientation effects

    DEFF Research Database (Denmark)

    Duggen, Lars; Willatzen, Morten

    2017-01-01

    This paper presents a theoretical investigation of phonon dispersion in piezoelectric slabs of hexagonal crystal symmetry (wurtzite). Specifically we solve the fully coupled dispersion relations in a GaN free standing quantum well by varying the crystal growth direction from the [001] axis...

  8. Crystal growth and scintillation properties of Nd:CaF.sub.2./sub..

    Czech Academy of Sciences Publication Activity Database

    Tanaka, H.; Kawaguchi, N.; Abe, N.; Furuya, Y.; Yokota, Y.; Yanagida, T.; Pejchal, Jan; Nikl, Martin; Kawazoe, Y.; Yoshikawa, A.

    2011-01-01

    Roč. 33, č. 3 (2011), 284-287 ISSN 0925- 3467 Institutional research plan: CEZ:AV0Z10100521 Keywords : fluoride * single crystal * crystal growth from the melt * Nd 3+ 5d-4f * radiation * scintillator Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.023, year: 2011

  9. Growth and study of barium oxalate single crystals in agar gel

    Indian Academy of Sciences (India)

    Barium oxalate was grown in agar gel at ambient temperature. The effect of various parameters like gel concentration, gel setting time and concentration of the reactants on the growth of these crystals was studied. Prismatic platy shaped spherulites and dendrites were obtained. The grown crystals were characterized by ...

  10. Lattice Boltzmann simulation of water isotope fractionation during ice crystal growth in clouds

    Science.gov (United States)

    Lu, Guoping; DePaolo, Donald J.

    2016-05-01

    We describe a lattice Boltzmann (LB) method for simulating water isotope fractionation during diffusion-limited ice crystal growth by vapor deposition from water-oversaturated air. These conditions apply to the growth of snow crystals in clouds where the vapor composition is controlled by the presence of both ice crystals and water droplets. Modeling of water condensation with the LB method has the advantage of allowing concentration fields to evolve based on local conditions so that the controls on grain shapes of the condensed phase can be studied simultaneously with the controls on isotopic composition and growth rate. Water isotope fractionation during snow crystal growth involves kinetic effects due to diffusion of water vapor in air, which requires careful consideration of the boundary conditions at the ice-vapor interface. The boundary condition is relatively simple for water isotopes because the molecular exchange rate for water at the interface is large compared to the crystal growth rate. Our results for the bulk crystal isotopic composition are consistent with simpler models using analytical solutions for radial geometry. However, the model results are sufficiently different for oxygen isotopes that they could affect the interpretation of D-excess values of snow and ice. The extent of vapor oversaturation plays a major role in determining the water isotope fractionation as well as the degree of dendritic growth. Departures from isotopic equilibrium increase at colder temperatures as diffusivity decreases. Dendritic crystals are isotopically heterogeneous. Isotopic variations within individual snow crystals could yield information on the microphysics of ice condensation as well as on the accommodation or sticking coefficient of water associated with vapor deposition. Our results are ultimately a first step in implementing LB models for kinetically controlled condensation or precipitation reactions, but needs to be extended also to cases where the

  11. The transport phenomena during the growth of ZnTe crystal by the temperature gradient solution growth technique

    Science.gov (United States)

    Yin, Liying; Jie, Wanqi; Wang, Tao; Zhou, Boru; Yang, Fan

    2017-03-01

    A numerical model is developed to simulate the temperature field, the thermosolutal convection, the solute segregation and the growth interface morphology during the growth of ZnTe crystal from Te rich solution by the temperature gradient solution growth (TGSG) technique. Effects of the temperature gradient on the transport phenomena, the growth interface morphology and the growth rate are examined. The influences of the latent heat and the thermal conductivity of ZnTe crystal on the transport phenomena and the growth interface are also discussed. We find that the mass transfer of ZnTe in the solution is very slow because of the low diffusion coefficient and the lack of mixing in the lower part of the solution. During the growth, dilute solution with high density and low growth temperature accumulates in the central region of the growth interface, making the growth interface change into two distinct parts. The inner part is very concave, while the outer part is relatively flat. Growth conditions in front of the two parts of the growth interface are different. The crystalline quality of the inner part of the ingot is predicted to be worse than that of the outer part. High temperature gradient can significantly increase the growth rate, and avoid the diffusion controlled growth to some extent.

  12. Radioactive waste melting furnace

    International Nuclear Information System (INIS)

    Nakayama, Junpei.

    1997-01-01

    The present invention provides a radioactive waste melting furnace excellent in heat insulating property, capable of exchanging only refractory materials with lesser amount of contamination. Namely, an heat insulation layer is disposed on the outer wall of the melting furnace. A refractory layer is disposed on the inner wall being in contact with molten materials in the melting furnace. A metal vessel covering the refractory layer is interposed between the heat insulation layer and the refractory layer. In addition, a metal outer shell covering the heat insulation layer is disposed on the heat insulation layer on the outer wall of the melting furnace. Bricks comprising, for example, alumina, carbon, zircon, magnesia or chromia having a low heat conductivity are used for the outer wall heat insulation layer irrespective of the melting performance. The refractory layer on the inner wall is made of bricks comprising chromia, alumina and zircon as molten materials of low basicity and chromia and magnesia as molten materials of high basicity. The materials of the metal vessel may be ordinary carbon steels, cast irons, or stainless steels. The refractory layer is taken out from the melting furnace together with the metal vessel, and only the refractory layer can be removed. Radiation contamination is eliminated. The metal vessel can be used again. (I.S.)

  13. Coupling between Molecular Mobility and Kinetics of Crystal Growth in a Hydrogen-Bonded Liquid

    DEFF Research Database (Denmark)

    Sanz, Alejandro; Niss, Kristine

    2017-01-01

    Our aim here is to gain new insight into the nature of the crystalline phase formed in supercooled glycerol near the glass transition temperature and to establish the interrelationship between the kinetics of crystal growth and fundamental dynamic properties. The liquid’s dynamics...... rate. The coupling between dynamic properties, such as dielectric α relaxation time, viscosity, and self-diffusion coefficient, and the characteristic crystal growth time is analyzed. We find that the crystal growth time scales with the glycerol’s self-diffusion coefficient as taucryst ∝ D−0...... and the crystalline development in glycerol, a hydrogen-bonded liquid, is studied by means of dielectric spectroscopy. We monitored the kinetics of crystallization by isothermal treatment at temperatures between 220 and 240 K (Tg = 185 K). Given the thermal protocol employed, we stimulated the growth...

  14. Study on growth techniques and macro defects of large-size Nd:YAG laser crystal

    Science.gov (United States)

    Quan, Jiliang; Yang, Xin; Yang, Mingming; Ma, Decai; Huang, Jinqiang; Zhu, Yunzhong; Wang, Biao

    2018-02-01

    Large-size neodymium-doped yttrium aluminum garnet (Nd:YAG) single crystals were grown by the Czochralski method. The extinction ratio and wavefront distortion of the crystal were tested to determine the optical homogeneity. Moreover, under different growth conditions, the macro defects of inclusion, striations, and cracking in the as-grown Nd:YAG crystals were analyzed. Specifically, the inclusion defects were characterized using scanning electron microscopy and energy dispersive spectroscopy. The stresses of growth striations and cracking were studied via a parallel plane polariscope. These results demonstrate that improper growth parameters and temperature fields can enhance defects significantly. Thus, by adjusting the growth parameters and optimizing the thermal environment, high-optical-quality Nd:YAG crystals with a diameter of 80 mm and a total length of 400 mm have been obtained successfully.

  15. Monitoring and Characterization of Crystal Nucleation and Growth during Batch Crystallization

    NARCIS (Netherlands)

    Kadam, S.S.

    2012-01-01

    Batch crystallization is commonly used in pharmaceutical, agrochemical, specialty and fine chemicals industry. The advantages of batch crystallization lie in its ease of operation and the relatively simple equipment that can be used. On the other hand a major disadvantage associated with it is the

  16. Crystal growth and magnetic property of YFeO3 crystal

    Indian Academy of Sciences (India)

    tional homogeneities, crystalline qualities, inclusion defects, second phases and surface morphology have been inves- tigated on the YFeO3 crystals grown by the .... carried out systematically on magnetic property of YFeO3 crystal in the future. Acknowledgements. The authors would like to acknowledge the financial sup-.

  17. On the growth of calcium tartrate tetrahydrate single crystals

    Indian Academy of Sciences (India)

    The grown crystals were characterized by atomic absorption spectroscopy (AAS), X-ray diffraction analysis (XRD), microhardness measurement, Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and differential thermal analysis (DTA). The results obtained are compared with the previous work.

  18. Crystal growth and comparison of vibrational and thermal properties ...

    Indian Academy of Sciences (India)

    Keywords. Urea thiourea mercuric sulphate; urea thiourea mercuric chloride; nonlinear optic crystals; ultraviolet–visible; Fourier transform infrared; atomic absorption spectroscopy; thermogravimetric analysis; differential thermogram analysis; second harmonic generation.

  19. Crystal growth, spectral and laser properties of Nd:LuAG single crystal

    International Nuclear Information System (INIS)

    Xu, X D; Meng, J Q; Cheng, Y; Li, D Z; Cheng, S S; Wu, F; Zhao, Z W; Wang, X D; Xu, J

    2009-01-01

    Nd:LuAG (Nd:Lu 3 Al 5 O 12 ) crystal was grown by the Czochralski method. X-ray powder diffraction experiments show that the Nd:LuAG crystal crystallizes in the cubic with space group Ia3d and has the cell parameter: a = 1.1907 nm, V = 1.6882 nm 3 . The absorption and fluorescence spectra of Nd:LuAG crystal at room temperature were investigated. With a fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Nd:LuAG crystal was demonstrated. The maximum output power at 1064 nm was obtained to be 3.8 W under the incident pump power of 17.3 W, with the optical conversion efficiency 22.0% and the slope efficiency 25.7%

  20. Crystal growth, spectral and laser properties of Nd:LuAG single crystal

    Science.gov (United States)

    Xu, X. D.; Wang, X. D.; Meng, J. Q.; Cheng, Y.; Li, D. Z.; Cheng, S. S.; Wu, F.; Zhao, Z. W.; Xu, J.

    2009-09-01

    Nd:LuAG (Nd:Lu3Al5O12) crystal was grown by the Czochralski method. X-ray powder diffraction experiments show that the Nd:LuAG crystal crystallizes in the cubic with space group Ia3d and has the cell parameter: a = 1.1907 nm, V = 1.6882 nm3. The absorption and fluorescence spectra of Nd:LuAG crystal at room temperature were investigated. With a fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Nd:LuAG crystal was demonstrated. The maximum output power at 1064 nm was obtained to be 3.8 W under the incident pump power of 17.3 W, with the optical conversion efficiency 22.0% and the slope efficiency 25.7%.

  1. Crystal growth, spectral and laser properties of Nd:LSAT single crystal

    Science.gov (United States)

    Hu, P. C.; Yin, J. G.; Zhao, C. C.; Gong, J.; He, X. M.; Zhang, L. H.; Liang, X. Y.; Hang, Y.

    2011-10-01

    Nd:(La, Sr)(Al, Ta)O3 (Nd:LSAT) crystal was grown by the Czochralski method. The absorption and fluorescence spectra of Nd:LSAT crystal at room temperature were investigated. With a fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Nd:LSAT crystal was demonstrated. The result of diode-pumped laser operation of Nd:LSAT crystal single crystal is reported for what is to our knowledge the first time. The maximum output power at 1064 nm was obtained to be 165 mW under the incident pump power of 3 W, with the slope efficiency 10.9%.

  2. Nanohybrid shish kebab paper: Crystal growth and film properties

    Science.gov (United States)

    Laird, Eric D.; Li, Bing; Cheng, Shan; Dong, Bin; Bose, Ranjita K.; Lau, Kenneth K. S.; Li, Christopher Y.

    2012-02-01

    Polyethylene single crystals were uniformly grown heterogeneously from carbon nanotubes (CNTs) in solution, forming the nanohybrid shish kebab (NHSK) structure. We demonstrate that highly uniform, free-standing nanohybrid buckypaper with high CNT contents (13-70%) could be produced from vacuum-filtrated polymer single crystal-decorated CNTs. In this way, polymer crystals served as unique spacers for CNTs so that uniform hybrid buckypaper films could be obtained without CNT agglomeration. Wetting techniques, thermal analysis, and scanning electron microscopy were used to elucidate the effect of polymer single crystals on the resultant structure. Surface roughness of NHSK paper could be controlled by tuning the polymer single crystal size (CNT separation distance). Superhydrophobic NHSK papers were obtained with high surface adhesion, which mimics the rose petal effect. Conductivity of the NHSK papers also varied with polymer crystal size. Great enhancement of important properties could be achieved through the formation of ternary hybrids. To that end, initiated- and oxidative chemical vapor deposition methods extend NHSK buckypaper applicability by providing functional polymer surfaces. NHSK papers may find applications in sensors, electrochemical devices and coatings.

  3. Crystal structure, growth and nonlinear optical studies of isonicotinamide p-nitrophenol: A new organic crystal for optical limiting applications

    Science.gov (United States)

    Vijayalakshmi, A.; Vidyavathy, B.; Vinitha, G.

    2016-08-01

    Isonicotinamide p-nitrophenol (ICPNP), a new organic material, was synthesized using methanol solvent. Single crystals of ICPNP were grown using a slow evaporation solution growth technique. Crystal structure of ICPNP is elucidated by single crystal X-ray diffraction analysis. It belongs to monoclinic crystal system with space group of P21/c. It forms two dimensional networks by O-H…O, N-H…O and C-H…O hydrogen bonds. The molecular structure of ICPNP was further confirmed by Fourier transform infrared (FTIR) spectral analysis. The optical transmittance range and the lower cut-off wavelength (421 nm) with the optical band gap (2.90 eV) of the ICPNP crystal were determined by UV-vis-NIR spectral study. Thermal behavior of ICPNP was studied by thermo gravimetric and differential thermal analyses (TG/DTA). The relative dielectric permittivity was calculated for various temperature ranges. Laser damage threshold of ICPNP crystal was found to be 1.9 GW/cm2 using an Nd:YAG laser. A Z-scan technique was employed to measure the nonlinear absorption coefficient, nonlinear refractive index and nonlinear optical susceptibility. Optical limiting behavior of ICPNP was observed at 35 mW input power.

  4. Ignition and growth modeling of detonation reaction zone experiments on single crystals of PETN and HMX

    Science.gov (United States)

    White, Bradley W.; Tarver, Craig M.

    2017-01-01

    It has long been known that detonating single crystals of solid explosives have much larger failure diameters than those of heterogeneous charges of the same explosive pressed or cast to 98 - 99% theoretical maximum density (TMD). In 1957, Holland et al. demonstrated that PETN single crystals have failure diameters of about 8 mm, whereas heterogeneous PETN charges have failure diameters of less than 0.5 mm. Recently, Fedorov et al. quantitatively determined nanosecond time resolved detonation reaction zone profiles of single crystals of PETN and HMX by measuring the interface particle velocity histories of the detonating crystals and LiF windows using a PDV system. The measured reaction zone time durations for PETN and HMX single crystal detonations were approximately 100 and 260 nanoseconds, respectively. These experiments provided the necessary data to develop Ignition and Growth (I&G) reactive flow model parameters for the single crystal detonation reaction zones. Using these parameters, the calculated unconfined failure diameter of a PETN single crystal was 7.5 +/- 0.5 mm, close to the 8 mm experimental value. The calculated failure diameter of an unconfined HMX single crystal was 15 +/- 1 mm. The unconfined failure diameter of an HMX single crystal has not yet been determined precisely, but Fedorov et al. detonated 14 mm diameter crystals confined by detonating a HMX-based plastic bonded explosive (PBX) without initially overdriving the HMX crystals.

  5. Mediation of calcium oxalate crystal growth on human kidney epithelial cells with different degrees of injury

    International Nuclear Information System (INIS)

    Zhang Shen; Su Zexuan; Yao Xiuqiong; Peng Hua; Deng Suiping; Ouyang Jianming

    2012-01-01

    The current study examined the role of injured human kidney tubular epithelial cell (HKC) in the mediation of formation of calcium oxalate (CaOxa) crystals by means of scanning electronic microscopy and X-ray diffraction. HKC was injured using different concentrations of H 2 O 2 . Cell injury resulted in a significant decrease in cell viability and superoxide dismutase (SOD) concentration and an increase in the level of malondialdehyde (MDA) and expression of osteopontin (OPN). Injured cells not only promote nucleation and aggregation of CaOxa crystals, but also induce the formation of calcium oxalate monohydrate (COM) crystals that strongly adhere to cells. These results imply that injured HKCs promote stone formation by providing more nucleating sites for crystals, promoting the aggregation of crystals, and inducing the formation of COM crystals. - Graphical abstract: Injured cells promote nucleation and aggregation of CaOxa crystals, induce the formation of calcium oxalate monohydrate (COM) crystals. Highlights: ► A direct nucleation and growth of CaOxa crystals on both normal and injured cells. ► Stronger green fluorescence, i.e. OPN expression, was seen on the injury cell surface ► Injured cells promote nucleation and aggregation of CaOxa crystals. ► Injured cells induce the formation of calcium oxalate monohydrate crystals. ► H 2 O 2 decrease cell viability in a dose-dependent manner at 0.1–1 mmol/L.

  6. Single crystal growth, crystal structure and characterization of a novel crystal: L-arginine 4-nitrophenolate 4-nitrophenol dehydrate (LAPP)

    Science.gov (United States)

    Wang, L. N.; Wang, X. Q.; Zhang, G. H.; Liu, X. T.; Sun, Z. H.; Sun, G. H.; Wang, L.; Yu, W. T.; Xu, D.

    2011-07-01

    A novel organic crystal, L-arginine 4-nitrophenolate 4-nitrophenol dehydrate (LAPP), synthesized and grown from aqueous solution, is presented. X-ray single diffraction shows that LAPP belongs to the monoclinic crystallographic system with space group P2 1. FT-IR and UV/vis/NIR transmission spectra have been employed to characterize the crystal. The computational calculation based on the density functional theory at the B3LYP/6-31G (d, p) level has been used to compute the first-order hyperpolarizability of LAPP relating to different molecular models. The morphology, nonlinear characteristic and thermal stability of the crystal have also been investigated.

  7. Crystal growth and scintillation properties of Pr-doped SrI2 single crystals

    Science.gov (United States)

    Yokota, Yuui; Ito, Tomoki; Yoshino, Masao; Yamaji, Akihiro; Ohashi, Yuji; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira

    2018-04-01

    Pr-doped SrI2 (Pr:SrI2) single crystals with various Pr concentrations were grown by the halide-micro-pulling-down (H-μ-PD) method, and the scintillation properties were investigated. Pr1%:SrI2 single crystal with high transparency could be grown by the H-μ-PD method while Pr2, 3 and 5%:SrI2 single crystals included some cracks and opaque parts. In the photoluminescence spectrum of the Pr1%:SrI2 single crystal, an emission peak originated from the Pr3+ ion was observed around 435 nm while the radioluminescence spectra showed an emission peak around 535 nm for the undoped SrI2 and Pr:SrI2 single crystals. Light yields of Pr1, 2, 3 and 5%:SrI2 single crystals under γ-ray irradiation were 7700, 8700, 7200 and 6700 photons/MeV, respectively. Decay times of Pr1 and 2%:SrI2 single crystals under γ-ray irradiation were 55.9 and 35.0 ns of the fast decay component, and 435 and 408 ns of the slow decay component, respectively.

  8. Crystal growth of K2TiGe3O9 in the glass

    Directory of Open Access Journals (Sweden)

    Grujić Snežana R.

    2010-01-01

    Full Text Available The kinetics and mechanism of isothermal crystal growth of K2TiGe3O9 from a glass of the same stoichiometric composition were studied. The crystal growth rate U = 1 x 10-11-1.27 x 10-10 m s-1 was experimentally determined in the temperature interval of t = 540-600°C. In the range of high undercooling, Δt=435-375°C, spherical crystals growing at (374 ± 19 kJ mol-1 was observed.

  9. An instrument for in situ growth rate characterization of mechanically strained crystals

    Science.gov (United States)

    Zikic, A. M.; Ristic, R. I.; Sherwood, J. N.

    1998-07-01

    The crystal growth and dissolution characteristics of a certain material can be considerably influenced by the strain present in a growing (dissolving) crystal. Strain can be induced in various ways. One of the most common and always present in industrial processes, where attrition processes are always accompanied by generation of mechanical strain in a newly formed small crystal fragments, is mechanical stressing, in situ, during preparation and handling. To gain deeper insights into some aspects of this phenomenon, a sophisticated equipment is needed for in situ controlled stressing of extremely brittle and fragile crystals. For this purpose, we have developed an apparatus which comprises a specially designed straining cell coupled with a laser Michelson interferometer for growth rate measurements. The straining cell is designed to accommodate crystals that undergo fracture below 200 microstrains. The stress imposed on a crystal is computer controlled with a precision of approximately 5%. Details of the instrument are given together with two examples of straining in situ brittle paracetamol and plastic sodium nitrate crystals. The measured changes in growth rate of a paracetamol crystal, in the quasi linear region 0-70 kPa are estimated to be (-9.4±0.1)×10-11 m/s/kPa.

  10. GROWTH RATE DISPERSION (GRD OF THE (010 FACE OF BORAX CRYSTALS IN FLOWING SOLUTION

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available The growth rates of borax crystals from aqueous solutions in the (010 direction at various flow rates were measured. The observed variations of the growth rate can be represented by a normal distribution.  It was found that there is no correlation between growth rate distribution and solution flow under these experimental conditions.   Keywords: Growth rate dispersion (GRD, borax, flow rate

  11. Synthesis, growth, structure determination and optical properties of chalcone derivative single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Karthi, S., E-mail: girijaeaswaradas@gmail.com; Girija, E. K., E-mail: girijaeaswaradas@gmail.com [Department of Physics, Periyar University, Salem - 636011 (India)

    2014-04-24

    Acquiring large nonlinear optical (NLO) efficient organic material is essential for the development of optoelectronics and photonic devices. Chalcone is the donor - Π - acceptor - Π - donor (D-Π-A-Π-D) type conjugated molecule with appreciable hyperpolarizability of potential interest in NLO applications. The addition of vinyl and electron donor groups in the chalcone molecule may enhance the second harmonic generation (SHG) efficiency. Here we report the synthesis, crystal growth and characterization of a chalcone derivative 1-(4-methylphenyl)-5-(4-methoxyphenyl)-penta-2,4-dien-1-one (MPMPP). The MPMPP crystal was grown by slow evaporation solution growth technique from acetone. The grown crystal structure was studied by single crystal X-ray diffraction. The SHG efficiency of the grown crystal was determined by Kurtz and Perry method.

  12. Potassium-cobalt sulphate crystal growth assisted by low frequency vibrations

    Science.gov (United States)

    Sadovsky, A.; Ermochenkov, I.; Dubovenko, E.; Sukhanova, E.; Bebyakin, M.; Dubov, V.; Avetissov, I.

    2018-02-01

    Single crystals of K2Co(SO4)2·6H2O were grown from solution using the temperature reduction method enhanced by the axial low frequency vibration control technique (AVC-technique). Physical modeling of heat-mass transfer in solution under the AVC action was performed. The growth rate of the AVC grown crystal was found to be twice that of the crystal grown under natural convection conditions. Analysis of spectral characteristics (absorption and Raman spectra) as well as structural properties (dislocation density and microhardness) of the grown crystals showed the significant superiority of the AVC technique for the growth of K2Co(SO4)2·6H2O crystals.

  13. Crystal growth and characterization of a semiorganic nonlinear optical single crystal of gamma glycine

    International Nuclear Information System (INIS)

    Prakash, J. Thomas Joseph; Kumararaman, S.

    2008-01-01

    Gamma glycine has been successfully synthesized by taking glycine and potassium chloride and single crystals have been grown by solvent evaporation method for the first time. The grown single crystals have been analyzed with XRD, Fourier transform infrared (FTIR), and thermo gravimetric and differential thermal analyses (TG/DTA) measurements. Its mechanical behavior has been assessed by Vickers microhardness measurements. Its nonlinear optical property has been tested by Kurtz powder technique. Its optical behavior was examined by UV-vis., and found that the crystal is transparent in the region between 240 and 1200 nm. Hence, it may be very much useful for the second harmonic generation (SHG) applications

  14. Crystal growth, spectroscopic and laser properties of Tm:LuAG crystal

    Science.gov (United States)

    Xu, X. D.; Wang, X. D.; Lin, Z. F.; Cheng, Y.; Li, D. Z.; Cheng, S. S.; Wu, F.; Zhao, Z. W.; Gao, C. Q.; Gao, M. W.; Xu, J.

    2009-11-01

    Tm:Lu3Al5O12 (Tm:LuAG) crystal was grown by the Czochralski method. The segregation coefficient was measured by Inductively Coupled Plasma Atomic Emission Spectrometer. The cell parameters were analyzed with X-ray powder diffraction experiments. The absorption and fluorescence spectra of Tm:LuAG crystal at room temperature were investigated. With a 20 W fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Tm:LuAG crystal was demonstrated. The maximum output power at 2020 nm was obtained to be 3.04 W, and the slope efficiency was 25.3%.

  15. Sublimation growth of nonpolar AlN single crystals and defect characterization

    Energy Technology Data Exchange (ETDEWEB)

    Satoh, Issei; Arakawa, Satoshi; Tanizaki, Keisuke; Miyanaga, Michimasa; Yamamoto, Yoshiyuki [Sumitomo Electric Industries, Ltd., 1-1-1 Koyakita, Itami, Hyogo 664-0016 (Japan)

    2010-07-15

    Sublimation growth of nonpolar AlN single crystals was investigated. The crystals were prepared in two methods: By slicing along the m -plane from c -plane-grown thick crystals, and by heteroepitaxial growth on m -plane SiC substrates. Defects of the crystals were observed by high-resolution transmission electron microscope. Dislocation density in AlN/SiC (0001) decreased significantly at about 1.5 {mu}m above the interface, while stacking faults initiated from the interface toward the growth surface in AlN/SiC (1-100). With increasing crystal thickness, the dislocation density decreases up to 5 x 10{sup 4}/cm{sup 2} at the thickness of 10 mm. In the AlN single crystal grown on SiC (0001), it is noteworthy that the dislocations are localized around the AlN/SiC interface and that far fewer dislocations occur near the growth surface. High-crystallinity AlN thick single crystals could be grown on SiC (0001) substrates. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Selective Acceleration of Crystal Growth of Indomethacin Polymorphs by Low-Concentration Poly(ethylene oxide).

    Science.gov (United States)

    Shi, Qin; Zhang, Jie; Zhang, Chen; Jiang, Jing; Tao, Jun; Zhou, Dongshan; Cai, Ting

    2017-12-04

    Physical stability of pharmaceutical amorphous solid dispersions is one of the critical attributes to the successful development of the formulation. Herein, we studied the impact of low-concentration poly(ethylene oxide) (PEO) on the crystallization rates of three polymorphs of indomethacin (IMC, γ-, α-, and δ-form). We observed that the addition of 3% w/w PEO significantly increased the crystal growth rates of γ-form and α-form of IMC, but had a negligible effect on the δ-form. The reduction of the activation energy for the crystal growth of IMC polymorphs after adding the PEO follows the order γ-form > α-form > δ-form, which is consistent with the trend toward the accelerating effects of PEO on the crystal growth rates of three polymorphs. With the addition of low-concentration PEO, there is an increase of molecular mobility of IMC as evidenced by the decreased structural relaxation times and viscosities. This study suggests that the substantially different effects of PEO on the crystal growth rates of IMC polymorphs are attributable to the different adsorption of PEO on the crystal surface of those polymorphs, which in turn exerts a selective accelerating effect on IMC molecules to organize into the different crystalline phases. These findings are relevant for understanding the crystallization behavior of amorphous solid dispersions containing polymorphic drugs.

  17. The influence of a homologous protein impurity on lysozyme crystal growth

    Science.gov (United States)

    Bhamidi, V.; Hanson, B. L.; Edmundson, A.; Skrzypczak-Jankun, E.; Schall, C.

    1999-08-01

    The effect of a structurally similar protein impurity, turkey ( Meleagris gallopavo) egg-white lysozyme (TEWL) on crystallization of the host protein, hen-egg-white lysozyme (HEWL) from chicken ( Gallus gallus) was studied under varying impurity and host solution concentrations. A change in morphology is observed when crystals of HEWL are grown in the presence of TEWL. As the relative amount of TEWL increases, HEWL crystals become more elongated in the [0 0 1] direction. Elongation is more pronounced in samples with lower initial concentrations of HEWL than in samples with higher initial concentrations. This behavior is consistent with that of impurities in small molecule crystal growth and with predictions based on the Kubota-Mullin model. The observed effect on the growth process can be attributed to the apparent inhibition in the [1 1 0] crystal growth direction of HEWL by TEWL since slowly growing faces become dominant faces in crystal growth. Incorporation of TEWL into HEWL crystals grown in a sitting drop batch method was measured using cation exchange chromatography. The results indicate that impurity incorporation is associated with increasing supersaturation. This conclusion is consistent with a kinetically controlled process of impurity incorporation. The observed impurity effects are most probably associated with the interchange of glutamine in position 41 of HEWL by histidine in TEWL.

  18. Unidirectional growth and characterization of L-arginine monohydrochloride monohydrate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sangeetha, K. [Department of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu 620 024 (India); Babu, R. Ramesh, E-mail: rampap2k@yahoo.co.in [Department of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu 620 024 (India); Bhagavannarayana, G. [Materials Characterization Division, National Physical Laboratory, New Delhi 110 012 (India); Ramamurthi, K. [Department of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu 620 024 (India)

    2011-10-17

    Highlights: {yields} L-Arginine monohydrochloride monohydrate (LAHCl) single crystal was grown successfully by unidirectional solution growth method for the first time. {yields} High crystalline perfection was observed for UDS grown crystal compared to CS grown crystal. {yields} The optical transparency and mechanical stability are high for UDS grown LAHCl single crystal. {yields} Optical birefringence measurement on this material. {yields} The piezoelectric resonance frequencies observation - first time observation on this material. - Abstract: L-Arginine monohydrochloride monohydrate (LAHCl) single crystals were grown successfully by conventional and unidirectional solution growth methods. The crystalline perfection of grown crystals was analyzed by high-resolution X-ray diffraction. The linear optical transmittance, mechanical stability of conventional and unidirectional grown LAHCl single crystals were analyzed and compared along (0 0 1) plane. The refractive index and birefringence of LAHCl single crystals were also measured using He-Ne laser source. From the dielectric studies, piezoelectric resonance frequencies were observed in kHz frequency range for both conventional and unidirectional grown LAHCl single crystals along (0 0 1) plane.

  19. Growth Rate and Morphology of a Single Calcium Carbonate Crystal on Polysulfone Film Measured with Time Lapse Raman Micro Spectroscopy

    NARCIS (Netherlands)

    Liszka, B.; Lenferink, Aufrid T.M.; Otto, Cornelis

    2016-01-01

    The growth of single, self- nucleated calcium carbonate crystals on a polysulfone (PSU) film was investigated with high resolution, time lapse Raman imaging. The Raman images were acquired on the interface of the polymer with the crystal. The growth of crystals could thus be followed in time. PSU is

  20. The crystallization of a solid solution in a solvent and the stability of a growth interface

    International Nuclear Information System (INIS)

    Malmejac, Yves

    1971-03-01

    The potential uses of germanium-silicon alloys as thermoelectric generators in hitherto unexploited temperature ranges initiated the present study. Many delicate problems are encountered in the classical methods of preparation. An original technique was sought for crystallization in a metallic solvent. The thermodynamic equilibria between the various phases of the ternary System used were studied in order to justify the method used. The conditions (temperature and composition) were determined in which the cooling of a ternary liquid mixture induces the precipitation of a binary solid solution with the desired composition. If large crystals are to be obtained from the solid solution, metallic solvent precipitation must be replaced by a mono-directional solvent crystallization. The combined effect of a certain number of simple physical phenomena on the stability of a crystal liquid interface was studied: the morphological stability of the crystal growth interface is the first step towards obtaining perfect crystals. (author) [fr

  1. Defects in silicon effect on device performance and relationship to crystal growth conditions

    Science.gov (United States)

    Jastrzebski, L.

    1985-01-01

    A relationship between material defects in silicon and the performance of electronic devices will be described. A role which oxygen and carbon in silicon play during the defects generation process will be discussed. The electronic properties of silicon are a strong function of the oxygen state in the silicon. This state controls mechanical properties of silicon efficiency for internal gettering and formation of defects in the device's active area. In addition, to temperature, time, ambience, and the cooling/heating rates of high temperature treatments, the oxygen state is a function of the crystal growth process. The incorporation of carbon and oxygen into silicon crystal is controlled by geometry and rotation rates applied to crystal and crucible during crystal growths. Also, formation of nucleation centers for oxygen precipitation is influenced by the growth process, although there is still a controversy which parameters play a major role. All these factors will be reviewed with special emphasis on areas which are still ambiguous and controversial.

  2. Damping of Solute Convection During Crystal Growth by Applying Magnetic Field Gradients

    Science.gov (United States)

    Wakayama, Nobuko I.

    2005-06-01

    One of the advantages of crystal growth under microgravity conditions is the damping of solute convection that affects crystal quality. The mechanism of the dampening effect of magnetic field gradients, B(dB/dz), on solute convection was studied, and the magnitude of B(dB/dz) required for dampening was calculated. When the absolute value of mass magnetic susceptibility, χg, of a solute is about 70% of that of a solvent (e.g., KCl crystal growth from an aqueous solution) and the weight ratio is 0.26, the gradient to damp convection considerably is estimated to be -3018 T2/m. On the other hand, when the χg of the solute is nearly equal to that of the solvent [protein crystal growth (lysozyme)], a gradient of -1394 T2/m damps convection completely on the earth.

  3. Crystal growth and reflectivity studies of Zn1–xMnxTe crystals

    Indian Academy of Sciences (India)

    Unknown

    –2000 nm wavelength range. 3. Chemical analysis. Compositional analysis of the crystals is carried out using. EDAX technique. The average composition of the end compounds is within ± 5 % variation with respect to the target composition.

  4. Crystal growth, spectral properties, and laser demonstration of laser crystal Nd:LYSO

    International Nuclear Information System (INIS)

    Li, D Z; Xu, X D; Zhou, D H; Xia, C T; Wu, F; Zhuang, S D; Wang, Z P; Xu, J

    2010-01-01

    A Nd:LYSO crystal has been grown by the Czochralski technique. The cell parameters were analyzed with X-ray diffraction (XRD). The Judd-Ofelt intense parameters Ω 2,4,6 were obtained to be 2.65, 5.75, and 7.37×10 -20 cm 2 , respectively. The absorption and emission cross sections and the branching ratios were calculated. The large absorption cross section (6.14×10 -20 cm 2 ) and broad absorption band (5 nm) around 811 nm indicate that this crystal can be pumped efficiently by laser diodes. The broad emission band from the 4 F 3/2 multiplet shows that the crystal is a promising medium for ultrashort pulse lasers. Pumped by a laser diode, the maximum 814 mW continuous-wave laser output has been obtained with a slope efficiency of 28.9%. All the results show that this crystal is a promising laser material

  5. Investigating calcite growth rates using a quartz crystal microbalance with dissipation (QCM-D)

    Science.gov (United States)

    Cao, Bo; Stack, Andrew G.; Steefel, Carl I.; DePaolo, Donald J.; Lammers, Laura N.; Hu, Yandi

    2018-02-01

    Calcite precipitation plays a significant role in processes such as geological carbon sequestration and toxic metal sequestration and, yet, the rates and mechanisms of calcite growth under close to equilibrium conditions are far from well understood. In this study, a quartz crystal microbalance with dissipation (QCM-D) was used for the first time to measure macroscopic calcite growth rates. Calcite seed crystals were first nucleated and grown on sensors, then growth rates of calcite seed crystals were measured in real-time under close to equilibrium conditions (saturation index, SI = log ({Ca2+}/{CO32-}/Ksp) = 0.01-0.7, where {i} represent ion activities and Ksp = 10-8.48 is the calcite thermodynamic solubility constant). At the end of the experiments, total masses of calcite crystals on sensors measured by QCM-D and inductively coupled plasma mass spectrometry (ICP-MS) were consistent, validating the QCM-D measurements. Calcite growth rates measured by QCM-D were compared with reported macroscopic growth rates measured with auto-titration, ICP-MS, and microbalance. Calcite growth rates measured by QCM-D were also compared with microscopic growth rates measured by atomic force microscopy (AFM) and with rates predicted by two process-based crystal growth models. The discrepancies in growth rates among AFM measurements and model predictions appear to mainly arise from differences in step densities, and the step velocities were consistent among the AFM measurements as well as with both model predictions. Using the predicted steady-state step velocity and the measured step densities, both models predict well the growth rates measured using QCM-D and AFM. This study provides valuable insights into the effects of reactive site densities on calcite growth rate, which may help design future growth models to predict transient-state step densities.

  6. Bulk Crystal Growth, and High-Resolution X-ray Diffraction Results of LiZnAs Semiconductor Material

    Science.gov (United States)

    Montag, Benjamin W.; Reichenberger, Michael A.; Sunder, Madhana; Ugorowski, Philip B.; Nelson, Kyle A.; Henson, Luke C.; McGregor, Douglas S.

    2017-08-01

    LiZnAs is being explored as a candidate for solid-state neutron detectors. The compact form, solid-state device would have greater efficiency than present day gas-filled 3He and 10BF3 detectors. Devices fabricated from LiZnAs having either natural Li (nominally 7.5% 6Li) or enriched 6Li (usually 95% 6Li) as constituent atoms may provide a material for compact high efficiency neutron detectors. The 6Li( n, t)4He reaction yields a total Q-value of 4.78 MeV, an energy larger than that of the 10B reaction, which can easily be identified above background radiations. LiZnAs material was synthesized by preparing equimolar portions of Li, Zn, and As sealed under vacuum (10-6 Torr) in quartz ampoules lined with boron nitride and subsequently reacted in a compounding furnace (Montag et al. in J Cryst Growth 412:103, 2015). The raw synthesized LiZnAs was purified by a static vacuum sublimation in quartz (Montag et al. in J Cryst Growth 438:99, 2016). Bulk crystalline LiZnAs ingots were grown from the purified material with a high-temperature Bridgman-style growth process described here. One of the largest LiZnAs ingots harvested was 9.6 mm in diameter and 4.2 mm in length. Samples were harvested from the ingot and were characterized for crystallinity using a Bruker AXS Inc. D8 AXS Inc. D2 CRYSO, energy dispersive x-ray diffractometer, and a Bruker AXS Inc. D8 DISCOVER, high-resolution x-ray diffractometer equipped with molybdenum radiation, Gobel mirror, four bounce germanium monochromator and a scintillation detector. The primary beam divergence was determined to be 0.004°, using a single crystal Si standard. The x-ray based characterization revealed that the samples nucleated in the (110) direction and a high-resolution open detector rocking curve recorded on the (220) LiZnAs yielded a full width at half maximum (FWHM) of 0.235°. Sectional pole figures using off-axis reflections of the (211) LiZnAs confirmed in-plane ordering, and also indicated the presence of multiple

  7. Controlling Fundamental Fluctuations for Reproducible Growth of Large Single-Crystal Graphene.

    Science.gov (United States)

    Guo, Wei; Wu, Bin; Wang, Shuai; Liu, Yunqi

    2018-02-27

    The controlled growth of graphene by the chemical vapor deposition method is vital for its various applications; however, the reproducibility remains a great challenge. Here, using single-crystal graphene growth on a Cu surface as a model system, we demonstrate that a trace amount of H 2 O and O 2 impurity gases in the reaction chamber is key for the large fluctuation of graphene growth. By precisely controlling their parts per million level concentrations, centimeter-sized single-crystal graphene is obtained in a reliable manner with a maximum growth rate up to 190 μm min -1 . The roles of oxidants are elucidated as an effective modulator for both graphene nucleation density and growth rate. This control is more fundamental for reliable growth of graphene beyond previous findings and is expected to be useful for the growth of various 2D materials that are also sensitive to trace oxidant impurities.

  8. Synthesis, growth and characterization of a new nonlinear optical crystal: Glycinium hydrogen squarate (GHS)

    Science.gov (United States)

    Paramasivam, P.; Ramachandra Raja, C.

    Single crystals of glycinium hydrogen squarate (GHS) have been successfully synthesized and purity of the material has been increased by repeated recrystallization process. Single crystals were grown by slow evaporation solution growth technique using water and ethanol as solvents at room temperature. Then the grown crystal was characterized by different techniques for finding its suitability for device fabrications. The grown crystal was characterized by single crystal XRD, powder XRD, FT-IR, UV-Vis-NIR, 1H NMR, 13C NMR, SHG and DTA/TGA analyses respectively. From the single crystal XRD diffraction, the crystal system was identified as monoclinic. The presence of functional groups were identified by FT-IR analysis. The UV transparency cut-off wavelength of the grown crystal occurs at 342 nm. 1H NMR and 13C NMR spectroscopic studies were employed to elucidate the structure of the grown crystal. The second harmonic generation efficiency test by Kurtz-Perry technique showed positive result. The decomposition temperature of the grown crystal was studied by DTA/TGA analysis. The results observed from the characterization analyses show its suitability for NLO applications.

  9. Synthesis, growth and characterization of L-Phenylalaninium methanesulfonate nonlinear optical single crystal

    Science.gov (United States)

    Mangaiyarkarasi, K.; Ravichandran, A. T.; Anitha, K.; Manivel, A.

    2018-03-01

    The titled compound, L-Phenylalaninium methanesulfonate (LPA-MS) was synthesized and grown into single crystals by slow solvent evaporation solution growth technique in aqueous solution containing equimolar concentrations of L-phenylalanine and methanesulfonic acid at room temperature. The grown crystals were subjected to single crystal X-ray diffraction studies. It crystallizes in the monoclinic crystal structure with P21 space group and the unit cell parameters are a = 5.312 (10) Å, b = 8.883 (2) Å and c = 25.830 (7) Å. The functional groups of the LPA-MS crystal were confirmed with FT-IR and FT-Raman analysis. The carbon-hydrogen skeleton was confirmed with 1H NMR and 13C NMR analysis. TG-DTG and DSC studies were carried out to determine the thermal stability of the crystals. The optical transparency ranges were studied through UV-vis-spectroscopy and the crystal was found to be transparent in the visible region. The second Harmonic generation (SHG) efficiency of the grown LPA-MS crystal was measured by the Kurtz-Perry powder technique. The dipolar nature of the L-phenylalaninium methanesulfonate and the presence of the intermolecular hydrogen bonding between the molecules are the vital factors responsible for the existence of SHG activity in the crystal.

  10. Growth patterns of monosodium urate monohydrate (gouty and urinary) crystals in gel: An in vitro study.

    Science.gov (United States)

    Ahmed, Salman; Hasan, Muhammad Mohtasheemul; Mahmood, Zafar Alam

    2017-11-01

    Monosodium urate monohydrate crystals are deposited in peripheral joints causing gout and elicit an intense localized inflammatory attack whereas in collecting ducts and medullary interstitium as a urinary calculi which causes dysuria, nausea and hematuria. The purpose of present study is to observe possible growth patterns of monosodium urate monohydrate crystals. The crystals were grown in test tubes by single diffusion gel technique and were observed at 7th, 14th, 21st, 28th and 40th day. Needle and spherulite type crystals were observed at 14th day, while arboresque, crystal sheaves, densely branched, dumbbell, mushroom type spherulites, plumose and hexagonal prismatic crystals were observed for the first time. After 40th day complete spherulites were observed with their aggregates. The crystals were characterized by Scanning Electron Microscopy, Energy-Dispersive X-ray and Fourier Transform infra Red spectroscopies. The pattern of MSUM will be helpful to determine the role of different natural products in the modulation, inhibition or promotion of these crystals by affecting the shape, size, transparency, approximate number and total mass of growing crystals. In case of inhibition or modulation it will be helpful for evaluation the prophylactic management whereas the promotion of the crystal will give an idea about the risk factors of gout and kidney stones.

  11. Radial furnace shows promise for growing straight boron carbide whiskers

    Science.gov (United States)

    Feingold, E.

    1967-01-01

    Radial furnace, with a long graphite vaporization tube, maintains a uniform thermal gradient, favoring the growth of straight boron carbide whiskers. This concept seems to offer potential for both the quality and yield of whiskers.

  12. CMOS Thermal Ox and Diffusion Furnace: Tystar Tytan 2000

    Data.gov (United States)

    Federal Laboratory Consortium — Description:CORAL Names: CMOS Wet Ox, CMOS Dry Ox, Boron Doping (P-type), Phos. Doping (N-Type)This four-stack furnace bank is used for the thermal growth of silicon...

  13. L-alanine distribution in the growth pyramids of TGS crystals and its influence on the growth, switching and domain structure

    International Nuclear Information System (INIS)

    Brezina, B.; Havrankova, M.

    1985-01-01

    The full-faced crystals of triglycine sulphate (TGS) and deuterated homologs substituted by L-alanine (LATGS and LADTGS, resp.) were grown from growth solutions with various concentrations of the substituent. The distribution of L, alanine (L,al) in various growth pyramids of crystals was measured by the electrical switching method. The stability of domain structure of doped crystals was studied by the liquid crystal method. (author)

  14. Effect of zinc acetate addition on crystal growth, structural, optical, thermal properties of glycine single crystals

    Directory of Open Access Journals (Sweden)

    S. Anbu Chudar Azhagan

    2017-05-01

    Full Text Available In the present study, γ-glycine has been crystallized by using zinc acetate dihydrate as an additive for the first time by slow solvent evaporation method. The second harmonic conversion efficiency of γ-glycine crystal was determined using Kurtz and Perry powder technique and was found to be 3.66 times greater than that of standard inorganic material potassium dihydrogen phosphate (KDP. The analytical grade chemicals of glycine and zinc acetate dihydrate were taken in six different molar ratios: 1:0.2, 1:0.4, 1:0.6, 1:0.7, 1:0.8, and 1:0.9 respectively to find out the γ-polymorph of glycine. The lower molar concentration of zinc acetate yield only α-polymorph where as the higher molar concentration of zinc acetate inhibits the γ-polymorph of glycine which was confirmed by single crystal XRD and powder XRD studies. Inductively coupled plasma optical emission spectrometry (ICP-OES was carried out to quantify the concentration of zinc element in the grown glycine single crystals. The concentration of zinc element in the presence of grown γ-glycine single crystal is found to be 0.73 ppm. UV–Visible–NIR transmittance spectra were recorded for the samples to analyse the transparency in visible and near infrared region (NIR. The optical band gap Eg was estimated for γ-glycine single crystal using UV–Visible–NIR study. Functional groups present in the samples were identified by FTIR spectroscopic analysis. Differential scanning calorimetry technique was employed to determine the phase transition, thermal stability and melting point of the grown crystal.

  15. Crystal growth, FTIR and thermal characterization of bis ...

    Indian Academy of Sciences (India)

    The grown crystals were characterized by elemental analysis, powder X-ray diffraction, thermal analysis, nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infra-red spectroscopy (FTIR) techniques. The chemical ... The second harmonic generation behaviour was tested by Nd:YAG laser source.

  16. Growth and characterization of nonlinear optical single crystals: bis ...

    Indian Academy of Sciences (India)

    Administrator

    telecommunication, optical switching, optical frequency conversion, THz generation, electro-optical and inte- grated optics.1,2 In recent times, polar aromatic organic molecules have received great attention for NLO applica- tions. However, NLO properties of several inorganic crystals such as LiNbO3, GaP have been widely ...

  17. Crystal growth, electrical and photophysical properties of Tl2S ...

    Indian Academy of Sciences (India)

    The electrical conductivity measurements were extended to elucidate the temper- ature dependence of the Hall coefficient for Tl2S layered single crystals and to determine important physical parameters. Also the scattering mechanism for the charge carriers was elucidated and discussed in this section. In this experiment.

  18. Crystal growth, FTIR and thermal characterization of bis ...

    Indian Academy of Sciences (India)

    Quaternary phosphonium salts can be made into casts with commercially available polymeric sus- pension to form membranes for the mass transport of cations, anions and neutral species. [14]. However, no attempt has been made so far to crystallize these compounds and check their suitability for industrial applications.

  19. Crystal growth and characterization of calcium metaborate scintillators

    Czech Academy of Sciences Publication Activity Database

    Fujimoto, Y.; Yanagida, T.; Kawaguchi, N.; Fukuda, K.; Totsuka, D.; Watanabe, K.; Yamazaki, A.; Chani, V.; Nikl, Martin; Yoshikawa, A.

    2013-01-01

    Roč. 703, MAR (2013), s. 7-10 ISSN 0168-9002 Institutional support: RVO:68378271 Keywords : Czochralski method * single crystal * scintillator * calcium metaborate * luminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.316, year: 2013

  20. Phonon-enhanced crystal growth and lattice healing

    Science.gov (United States)

    Buonassisi, Anthony; Bertoni, Mariana; Newman, Bonna

    2013-05-28

    A system for modifying dislocation distributions in semiconductor materials is provided. The system includes one or more vibrational sources for producing at least one excitation of vibrational mode having phonon frequencies so as to enhance dislocation motion through a crystal lattice.

  1. Crystal growth of proteins, nucleic acids, and viruses in gels.

    Science.gov (United States)

    Lorber, Bernard; Sauter, Claude; Théobald-Dietrich, Anne; Moreno, Abel; Schellenberger, Pascale; Robert, Marie-Claire; Capelle, Bernard; Sanglier, Sarah; Potier, Noëlle; Giegé, Richard

    2009-11-01

    Medium-sized single crystals with perfect habits and no defect producing intense and well-resolved diffraction patterns are the dream of every protein crystallographer. Crystals of biological macromolecules possessing these characteristics can be prepared within a medium in which mass transport is restricted to diffusion. Chemical gels (like polysiloxane) and physical gels (such as agarose) provide such an environment and are therefore suitable for the crystallisation of biological macromolecules. Instructions for the preparation of each type of gel are given to urge crystal growers to apply diffusive media for enhancing crystallographic quality of their crystals. Examples of quality enhancement achieved with silica and agarose gels are given. Results obtained with other substances forming gel-like media (such as lipidic phases and cellulose derivatives) are presented. Finally, the use of gels in combination with capillary tubes for counter-diffusion experiments is discussed. Methods and techniques implemented with proteins can also be applied to nucleic acids and nucleoprotein assemblies such as viruses.

  2. Growth morphology of zinc tris(thiourea) sulphate crystals

    Indian Academy of Sciences (India)

    The crystal structure of ZTS involves extensive hydrogen bonding. In keeping with the current trend, the contribution of this bonding to the cohesive energy was computed by us through the Coulomb interaction term. The total expression for the interaction potential between two atoms A(r ) and A(r ), with formal charges q and ...

  3. On the growth of calcium tartrate tetrahydrate single crystals

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... The grown crystals were characterized by atomic absorption spectroscopy (AAS), X-ray diffraction analysis (XRD), microhardness measurement, Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and differential thermal analysis (DTA). The results obtained are compared with the ...

  4. Crystal growth and comparison of vibrational and thermal properties ...

    Indian Academy of Sciences (India)

    troscopy; thermogravimetric analysis; differential thermogram analysis; second harmonic generation. PACS Nos 32.30-r; .... present in the synthesized compound and to determine the molecular structure. To analyse qualitatively the ... This shows that the binding of metal with thiourea is through sulphur in both the crystals.

  5. Interfacial morphologies and growth modes of F.C.C. metallic crystals from liquid alloys

    International Nuclear Information System (INIS)

    Camel, Denis

    1980-01-01

    Equilibrium and growth morphologies of f.c.c. metallic crystals in contact with liquid alloys have been observed in-situ using transmission electron microscopy. These morphologies have been discussed in terms of atomic interfacial structure and growth mechanisms with the help of a statistical thermodynamic model which takes into account the effects of chemical interactions and interfacial adsorption. (author) [fr

  6. Translation effects on vertical Bridgman growth and optical, mechanical and surface analysis of 2-phenylphenol single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sadhasivam, S., E-mail: sadha.phy1@gmail.com [Department of Physics, Center for Crystal Growth, SSN College of Engineering, Tamil Nadu, India-603 110 (India); Perumal, Rajesh Narayana

    2016-05-06

    2-phenylphenol optical crystals were grown in cone ampoules using vertical Bridgman technique. Single crystal of 2-phenylphenol with 150 mm length has been grown. The inclination on the conical part of the ampoule reduces the growth defects in the 2-phenylphenol single crystal. The lattice parameters and structure studied using single crystal X-ray diffraction method. 2-phenylphenol single crystal belongs to orthorhombic space group Fdd2. The micro translation rate affects crystal growth of 2-phenylphenol crystal was studied. The translation rate dependent defects present in the crystal were investigated by transmittance, indentation and etching characterizations. The dislocation induced indentation crack lengths variations were studied. Etch pits and striations observed for the selective etchants furnish significant information on growth aspects and degree of defect present in the crystal.

  7. Effect of mechanical deformations on the growth of crystals (according to atomic force microscopy data)

    Science.gov (United States)

    Piskunova, N. N.; Askhabov, A. M.

    2017-05-01

    Nanosized morphological transformations occurring on the surface of a crystal in the area drawn by a probe needle during the growth of a scratch and the growth kinetics of crystals subjected to mechanical impact have been studied by atomic force microscopy (AFM). A series of experiments with mechanical impact on topographically different areas of a growing face (100) of a dioxidine crystal has been performed. It has been shown that even slight local contact between the probe needle and the surface on a nanoscale leads to essential crystallogenetic (morphological and kinetic) consequences, and its effect is perceptible for a long time. Among these consequences are the coarsening of stages, the appearance of great fluctuations in the growth rate of stages, the loss of morphological stability by the surface even at a distance of several tens of micrometers from the contact area, and also the phenomenon of simultaneous growth and dissolution in neighboring areas of stages.

  8. Crystal growth, spectroscopic characterization and laser performance of Tm/Mg:LiNbO3 crystal

    Science.gov (United States)

    Zhang, P. X.; Yin, J. G.; Zhang, R.; Li, H. Q.; Xu, J. Q.; Hang, Y.

    2014-03-01

    A Tm, Mg co-doped LiNbO3 crystal was grown by the traditional Czochralski method. The room-temperature absorption, photo-luminescence spectra and fluorescence lifetime of Tm3+ ions in the crystal have been investigated. The experimental results show that the co-doped of MgO can lead to the lengthening of the measured fluorescence lifetime of the upper Tm3+:3F4 level. Based on the Judd-Ofelt approach, the intensity parameters Ω2,4,6 of Tm3+ were calculated to be Ω2 (6.29 × 10-20 cm2), Ω4 (0.54 × 10-20 cm2) and Ω6 (0.79 × 10-20 cm2). Other spectroscopic parameters that relate to laser performance were also obtained. Non-photorefractive continuous wave laser operation with a Tm, Mg:LiNbO3 single crystal is demonstrated at room temperature for the first time. We obtained 1.026 W output power at 1.885 μm with a slope efficiency of near 14%, which, to the best of our knowledge, is the largest output power and the highest slope efficiency obtained for this crystal thus far. The output power was observed to be stable, and the crystal showed no sign of photorefractive damage.

  9. Control of melt-crystal interface shape during sapphire crystal growth by heat exchanger method

    Science.gov (United States)

    Wu, Ming; Liu, Lijun; Ma, Wencheng

    2017-09-01

    We numerically investigate the melt-crystal interface shape during the early stage of the solidification process when the crystal diameter increases. The contact angle between the melt-crystal interface and the crucible bottom wall is found obtuse during this stage, which is unfavorable for the crystal quality. We found that the obtuse contact angle is caused by the thermal resistance difference between the sapphire crystal and melt as well as the insufficient cooling effect of the crucible bottom. Two approaches are proposed to suppress the obtuse contact angle. The first approach is to increase the emissivity of the outer surface of crucible bottom. The second approach is to install a heat shield near the crucible bottom. The reduction of the emissivity of the heat shield is also favorable for the suppression of the obtuse contact angle. Compared with the increase of the emissivity of the crucible bottom, the installation of a heat shield is a more effective approach to prevent the appearance of an obtuse contact angle for the sake of reliability since a molybdenum heat shield can be reused and will not induce other impurities.

  10. Enhancement of mercuric iodide detector performance through crystal growth in microgravity: The roles of lattice order

    International Nuclear Information System (INIS)

    Steiner, B.; Laor, U.; Berg, L. van den

    1998-01-01

    The hole-mobility·carrier-lifetime product of α mercuric iodide high energy radiation detectors has been enhanced through vapor crystal growth in microgravity. This improvement is closely correlated with specific characteristics of the crystal lattice, which have been identified by high resolution synchrotron X-ray diffraction imaging. These structural features and the associated performance are now being approached in terrestrial growth of α mercuric iodide. Gravity may affect the uniformity of this crystal lattice in two distinct ways: (1) directly through deformation that it imposes on the lattice during growth and (2) indirectly through convection, which mixes any extraneous material. Inclusions associated with these processes harden the lattice and facilitate lattice folding. These changes affect the electronic parameters of detectors made from the crystals. As purification procedures are optimized, the incorporation of extraneous material is curtailed, enhancing electronic properties in spite of lattice flexing through loss of precipitation hardening. These studies provide insight into the contribution of various aspects of crystalline order in α-mercuric iodide crystals to property improvement. This knowledge has led to modification of requirements for starting materials, adjustment of physical vapor growth procedures, and change in crystal handling procedures. As a result, the electronic performance of terrestrially grown radiation detectors has been improved, and the authors provide evidence that further enhancement is still possible

  11. Low-Temperature Growth of Two-Dimensional Layered Chalcogenide Crystals on Liquid.

    Science.gov (United States)

    Zhou, Yubing; Deng, Bing; Zhou, Yu; Ren, Xibiao; Yin, Jianbo; Jin, Chuanhong; Liu, Zhongfan; Peng, Hailin

    2016-03-09

    The growth of high-quality two-dimensional (2D) layered chalcogenide crystals is highly important for practical applications in future electronics, optoelectronics, and photonics. Current route for the synthesis of 2D chalcogenide crystals by vapor deposition method mainly involves an energy intensive high-temperature growth process on solid substrates, often suffering from inhomogeneous nucleation density and grain size distribution. Here, we first demonstrate a facile vapor-phase synthesis of large-area high-quality 2D layered chalcogenide crystals on liquid metal surface with relatively low surface energy at a growth temperature as low as ∼100 °C. Uniform and large-domain-sized 2D crystals of GaSe and GaxIn1-xSe were grown on liquid metal surface even supported on a polyimide film. As-grown 2D GaSe crystals have been fabricated to flexible photodetectors, showing high photoresponse and excellent flexibility. Our strategy of energy-sustainable low-temperature growth on liquid metal surface may open a route to the synthesis of high-quality 2D crystals of Ga-, In-, Bi-, Hg-, Pb-, or Sn-based chalcogenides and halides.

  12. Imaging transport phenomena during lysozyme protein crystal growth by the hanging drop technique

    Science.gov (United States)

    Sethia Gupta, Anamika; Gupta, Rajive; Panigrahi, P. K.; Muralidhar, K.

    2013-06-01

    The present study reports the transport process that occurs during the growth of lysozyme protein crystals by the hanging drop technique. A rainbow schlieren technique has been employed for imaging changes in salt concentration. A one dimensional color filter is used to record the deflection of the light beam. An optical microscope and an X-ray crystallography unit are used to characterize the size, tetragonal shape and Bravais lattice constants of the grown crystals. A parametric study on the effect of drop composition, drop size, reservoir height and number of drops on the crystal size and quality is reported. Changes in refractive index are not large enough to create a meaningful schlieren image in the air gap between the drop and the reservoir. However, condensation of fresh water over the reservoir solution creates large changes in the concentration of NaCl, giving rise to clear color patterns in the schlieren images. These have been analyzed to obtain salt concentration profiles near the free surface of the reservoir solution as a function of time. The diffusion of fresh water into the reservoir solution at the early stages of crystal growth followed by the mass flux of salt from the bulk solution towards the free surface has been recorded. The overall crystal growth process can be classified into two regimes, as demarcated by the changes in slope of salt concentration within the reservoir. The salt concentration in the reservoir equilibrates at long times when the crystallization process is complete. Thus, transport processes in the reservoir emerge as the route to monitor protein crystal growth in the hanging drop configuration. Results show that crystal growth rate is faster for a higher lysozyme concentration, smaller drops, and larger reservoir heights.

  13. Investigation on the growth of DAST crystals of large surface area for THz applications

    International Nuclear Information System (INIS)

    Vijay, R. Jerald; Melikechi, N.; Thomas, Tina; Gunaseelan, R.; Arockiaraj, M. Antony; Sagayaraj, P.

    2012-01-01

    Graphical abstract: It is evident from the photographs that the crystal tend to grow as a needle (Fig. 1a) in the lower concentration region (2–3 g/200 mL); whereas, in the high concentration region (5 g/200 mL) though there is a marked enlargement in the size of the crystal, the morphology of the resulting DAST crystal is slightly irregular (Fig. 1d) in nature. Among the four concentrations employed, best result was obtained with the DAST–methanol solution of concentration 4 g/200 mL; which resulted in the DAST crystal of large surface area (270 mm 2 ) with high transparency and nearly square shape (Fig. 1c) in a growth period of 20–25 days. Highlights: ► DAST crystals of different sizes are obtained for different concentrations. ► The main focus is to grow DAST crystals with large surface area. ► Structural, optical, thermal and mechanical properties are investigated. - Abstract: The growth of high quality 4-N,N-dimethylamino-4-N-methyl-stilbazoliumtosylate (DAST) crystal with large surface area is reported by adopting the slope nucleation coupled slow evaporation method (SNM-SE). The structure and composition of the crystal are studied by single crystal X-ray diffraction and CHN analyses. The linear optical properties are investigated by UV–vis absorption. The melting point and thermal behavior of DAST are investigated using differential scanning calorimetric (DSC) and thermogravimetric analyses (TGA). The Vickers microhardness number (VHN) and work hardening coefficient of the grown crystal have been determined. The surface features of the DAST crystal are analyzed by scanning electron microscopy (SEM) and it confirmed the presence of narrow line defects (NLDs) in the sample.

  14. Free-falling Crystals: Biological Macromolecular Crystal Growth Studies in Low Earth Orbit

    Science.gov (United States)

    Judge, Russell A.; Snell, E. H.; Pusey, M. L.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Spacecraft orbiting the earth experience a reduced acceleration environment due to being in a state of continuous free-fall. This state colloquially termed microgravity, has produced improved X-ray diffraction quality crystals of biological macromolecules. Improvements in X-ray diffraction resolution (detail) or signal to noise, provide greater detail in the three-dimensional molecular structure providing information about the molecule, how it works, how to improve its function or how to impede it. Greater molecular detail obtained by crystallization in microgravity, has important implications for structural biology. In this article we examine the theories behind macromolecule crystal quality improvement in microgravity using results obtained from studies with the model protein, chicken egg white lysozyme.

  15. Effect of solvents on the bulk growth of 4-aminobenzophenone single crystals: A potential material for blue and green lasers

    Science.gov (United States)

    Natarajan, V.; Usharani, S.; Arivanandhan, M.; Anandan, P.; Hayakawa, Y.

    2015-06-01

    Although 4-aminobenzophenone (4-ABP) is the best derivative of benzophenone with 260 times higher second harmonic generation (SHG) efficiency than potassium dihydrogen phosphate (KDP), growth of high quality bulk crystal still remains a difficult task. In the present work, the effect of solvents on solubility and growth aspects of 4-ABP was investigated to grow inclusion free 4-ABP crystals. The growth processes were discussed based on solute-solvent interaction in two different growth media of ethyl acetate and ethanol. The growth rate and thereby solvent inclusions are relatively higher in ethyl acetate grown crystal than the crystal grown from ethanol. The structural, thermal and optical properties of 4-ABP crystals were studied. The enthalpy of 4-ABP melting process was estimated from differential thermal analysis. The optical transmission study shows that 4-ABP crystals grown from ethanol has high transparency compared to ethyl acetate grown sample due to solvent inclusion in the later crystal.

  16. Magnetic Field Applications in Semiconductor Crystal Growth and Metallurgy

    Science.gov (United States)

    Mazuruk, Konstantin; Ramachandran, Narayanan; Grugel, Richard; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    The Traveling Magnetic Field (TMF) technique, recently proposed to control meridional flow in electrically conducting melts, is reviewed. In particular, the natural convection damping capability of this technique has been numerically demonstrated with the implication of significantly improving crystal quality. Advantages of the traveling magnetic field, in comparison to the more mature rotating magnetic field method, are discussed. Finally, results of experiments with mixing metallic alloys in long ampoules using TMF is presented

  17. Ground Based Program for the Physical Analysis of Macromolecular Crystal Growth

    Science.gov (United States)

    Malkin, Alexander J.

    1999-01-01

    In a reported period in situ atomic force microscopy was utilized in our laboratory to study mechanisms of growth and kinetics of crystallization of ten protein and virus crystals. These included canavalin, thaumatin, apoferritin, lipase, catalase, t-RNA, lysozyme, xylanase, turnip yellow mosaic virus (TYMV) and satellite tobacco mosaic virus (STMV). We have also designed and constructed in our laboratory both in situ conventional two-beam Michelson and phase shift Mach-Zenhder interferometers. Computer software for the processing of the interferometric images was developed as well. Interferometric techniques were applied for studies of growth kinetics and transport phenomena in crystallization of several macromolecular crystals. As a result of this work we have published 21 papers and have given many presentations at international and national meetings. A list of these publications and conference presentations is attached.

  18. Growth of methyl 2-(2,4-dinitrophenyl)aminopropanoate single crystals

    Science.gov (United States)

    Perigaud, A.; Nicolau, Y. F.

    1986-12-01

    Methyl 2-(2,4-dinitrophenyl)aminopropanoate single crystals, 1 cm in diameter and 7 cm in length have been grown by a travelling-heater-Bridgman method in polyethylene tubes introduced into glass ampoules, at a growth rate of 1.5-6 mm/day. The starting material was synthesised and purified by recrystallization from methanol and by vacuum evaporation to a purity of 99.994%. The period of growth, and hence the length of the crystal, is limited due to melt decomposition and polycondensation. The b-axis of the crystals is always oriented at about 72° to the ampoule axis. Good quality single crystals have been obtained giving a FWHM of the Cu Kα (040) rocking curve of about 1'.

  19. Crystal growth and optical properties of Sm:CaNb2O6 single crystal

    International Nuclear Information System (INIS)

    Di Juqing; Xu Xiaodong; Xia Changtai; Zeng Huidan; Cheng Yan; Li Dongzhen; Zhou Dahua; Wu Feng; Cheng Jimeng; Xu Jun

    2012-01-01

    Highlights: ► Sm:CaNb 2 O 6 single crystal was grown by the Czochralski method. ► Thermal expansion coefficients and J–O parameters were calculated. ► We found that this crystal had high quantum efficiency of 97%. - Abstract: Sm:CaNb 2 O 6 single crystal has been grown by the Czochralski method. Its high-temperature X-ray powder diffraction, optical absorption, emission spectroscopic as well as lifetime have been studied. Thermal expansion coefficients (α), J–O parameters (Ω i ), radiative lifetime (τ rad ), branching ratios (β) and stimulated emission cross-sections (σ e ) were calculated. The quantum efficiency (η) was calculated to be 97%. The intense peak emission cross section at 610, 658 nm were calculated to be 2.40 × 10 −21 , 2.42 × 10 −21 cm 2 . These results indicate that Sm:CaNb 2 O 6 crystal has potential use in visible laser and photonic devices area.

  20. Crystal growth, spectral properties, and laser demonstration of laser crystal Nd:LYSO

    Science.gov (United States)

    Li, D. Z.; Xu, X. D.; Zhou, D. H.; Zhuang, S. D.; Wang, Z. P.; Xia, C. T.; Wu, F.; Xu, J.

    2010-11-01

    A Nd:LYSO crystal has been grown by the Czochralski technique. The cell parameters were analyzed with X-ray diffraction (XRD). The Judd-Ofelt intense parameters Ω2,4,6 were obtained to be 2.65, 5.75, and 7.37×10-20 cm2, respectively. The absorption and emission cross sections and the branching ratios were calculated. The large absorption cross section (6.14×10-20 cm2) and broad absorption band (5 nm) around 811 nm indicate that this crystal can be pumped efficiently by laser diodes. The broad emission band from the 4F3/2 multiplet shows that the crystal is a promising medium for ultrashort pulse lasers. Pumped by a laser diode, the maximum 814 mW continuous-wave laser output has been obtained with a slope efficiency of 28.9%. All the results show that this crystal is a promising laser material.

  1. Crystal growth and luminescence properties of Pr-doped LuLiF4 single crystal

    International Nuclear Information System (INIS)

    Sugiyama, Makoto; Yanagida, Takayuki; Yokota, Yuui; Kurosawa, Shunsuke; Fujimoto, Yutaka; Yoshikawa, Akira

    2013-01-01

    0.1, 1, and 3% Pr (with respect to Lu) doped LuLiF 4 (Pr:LuLiF 4 ) single crystals were grown by the micro-pulling-down (μ-PD) method. Transparency of the grown crystals was higher than 70% in the visible wavelength region with some absorption bands due to Pr 3+ 4f-4f transitions. Intense absorption bands related with the Pr 3+ 4f-5d transitions were observed at 190 and 215 nm. In radioluminescence spectra, Pr 3+ 5d-4f emissions were observed at 220, 240, 340, and 405 nm. In the pulse height spectra recorded under 137 Cs γ-ray excitation, the Pr 3% doped sample showed the highest light yield of 2050 photons/MeV and the scintillation decay time of it exhibited 23 and 72 ns also excited by 137 Cs γ-ray. -- Highlights: ► 0.1, 1, and 3% Pr-doped LuLiF 4 single crystals were grown by the μ-PD method. ► Pr 3+ 5d-4f emission peaks appeared at 220, 240, 340, and 405 nm ► The Pr 3%:LuLiF 4 crystal showed the highest light yield of 2050 photons/MeV

  2. Solubility and peculiarities of the yttrium-aluminium borate crystal growth

    Energy Technology Data Exchange (ETDEWEB)

    Azizov, A.V.; Leonyuk, N.I.; Rezvyj, V.R.; Timchenko, T.I.; Belov, N.V. (Moskovskij Gosudarstvennyj Univ. (USSR))

    The nature of crystallization media and crystallization peculiarities of YAl/sub 3/(BO/sub 3/)/sub 4/ yttrium-alluminium borate (YAB) were investigated. The investigation of YAB solubility was conducted in the melts of two different compositions: 88.1K/sub 2/Mo/sub 2/O/sub 10/-3.5V/sub 2/O/sub 3/-8.4B/sub 2/O/sub 3/ (1) and 89.5K/sub 2/Mo/sub 3/O/sub 10/ - - 10.5B/sub 2/O/sub 3/ (2) at 1060-900 deg C. The YAB crystals obtained from different crystallization media had different habit and morphology. The revealed peculiarities are significant for the choice of the YAB crystal growing conditions on orientated seedings: more rapid growth can be exercised along the (0001) face from the solution in the melt (2).

  3. Growth and characterization of 2-Methylimidazolium D-tartrate single crystal

    Science.gov (United States)

    Srinivasan, T. P.; Anandhi, S.; Gopalakrishnan, R.

    2011-03-01

    Single crystal of 2-Methylimidazolium D-tartrate (2MImdT; C8N2O6H12) has been grown by slow evaporation solution growth technique at room temperature using mixed solvents of ethanol and deionized water. Single crystal X-ray diffraction study confirms that 2-Methylimidazolium D-tartrate belongs to monoclinic crystal system with non-centrosymmetric space group P21. The Fourier transform infrared spectrum of 2-Methylimidazolium D-tartrate reveals the presence of methyl and carboxyl functional groups in the compound. The mechanical properties of 2MImdT crystal were studied. The theoretical factor group analysis predicts 168 optical modes in the title compound. The dielectric behavior of 2MImdT crystals was studied at different frequencies and temperatures. Decomposition and melting point of 2MImdT were found using thermal measurements. SHG behavior of the title compound was demonstrated using Q-switched Nd:YAG laser.

  4. Tabular silver halide crystals prepared by controlled Ostwald growth in the presence of dimethyl sulphoxide

    Energy Technology Data Exchange (ETDEWEB)

    Dyonizy, A.; Nowak, P.; Mora, C.; Krol-Gracz, A.; Michalak, E. [Institute of Physical and Theoretical Chemistry, Wroclaw University of Technology, Wybrzeze St. Wyspianskiego 27, 50-370 Wroclaw (Poland)

    2010-03-15

    The results of research in the size and shape of silver bromide crystals precipitated by the Ostwald controlled growth method at the presence of dimethyl sulphoxide were presented in the paper. The silver bromide crystals were produced in the form of microcrystal suspension stabilised by gelatine. In the course of the synthesis of crystals, the constant concentration of dimethyl sulphoxide, concentration of excessive bromide ions and the constant ionic strength were achieved. The tabular crystals of silver bromide with their average size of 50 {mu}m and their aspect ratio equal to 100 were obtained by means of this method. The suspensions of flat silver bromide crystals produced in this manner can be used in the production of high-sensitivity materials. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Effect of growth rate on the compositional variations in directionally solidified Hg(1-x)Cd/sub xSe/

    International Nuclear Information System (INIS)

    Andrews, R.N.

    1986-01-01

    Several Hg/sub 1-x/Cd/sub x/Se crystals of composition x = 0.2 were grown in a Bridgman-type directional solidification furnace at varying translation rates. The influence of growth rate on both the longitudinal and radial compositional uniformity for the crystals was determined using density measurements and infrared transmission-edge mapping

  6. Growth of CdZnTe Crystals for Radiation Detector Applications by Directional Solidification

    Science.gov (United States)

    Su, Ching-Hua

    2014-01-01

    Advances in Cadmium Zinc Telluride (Cd(sub 1-x)Zn(sub x)Te) growth techniques are needed for the production of large-scale arrays of gamma and x-ray astronomy. The research objective is to develop crystal growth recipes and techniques to obtain large, high quality CdZnTe single crystal with reduced defects, such as charge trapping, twinning, and tellurium precipitates, which degrade the performance of CdZnTe and, at the same time, to increase the yield of usable material from the CdZnTe ingot. A low gravity material experiment, "Crystal Growth of Ternary Compound Semiconductors in Low Gravity Environment", will be performed in the Material Science Research Rack (MSRR) on International Space Station (ISS). One section of the flight experiment is the melt growth of CdZnTe ternary compounds. This talk will focus on the ground-based studies on the growth of Cd(sub 0.80)Zn(sub 0.20)Te crystals for radiation detector applications by directional solidification. In this investigation, we have improved the properties that are most critical for the detector applications (electrical properties and crystalline quality): a) Electrical resistivity: use high purity starting materials (with reproducible impurity levels) and controlled Cd over pressure during growth to reproducibly balance the impurity levels and Cd vacancy concentration b) Crystalline quality: use ultra-clean growth ampoule (no wetting after growth), optimized thermal profile and ampoule design, as well as a technique for supercool reduction to growth large single crystal with high crystalline quality

  7. Method for single crystal growth of photovoltaic perovskite material and devices

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jinsong; Dong, Qingfeng

    2017-11-07

    Systems and methods for perovskite single crystal growth include using a low temperature solution process that employs a temperature gradient in a perovskite solution in a container, also including at least one small perovskite single crystal, and a substrate in the solution upon which substrate a perovskite crystal nucleates and grows, in part due to the temperature gradient in the solution and in part due to a temperature gradient in the substrate. For example, a top portion of the substrate external to the solution may be cooled.

  8. Enhancement of heat transfer in Czochralski growth of silicon crystals with a chemical cooling technique

    Science.gov (United States)

    Ding, Junling; Liu, Lijun; Zhao, Wenhan

    2017-06-01

    The cost of producing single-crystalline silicon with the Czochralski method can be reduced by promoting the crystal size and/or crystal pulling rate. However, more latent heat of solidification needs to be released from the melt-crystal (m-c) interface during the crystal growth process. In this study, the C-CO2 chemical endothermic reaction is proposed as a novel and efficient cooling technique to solve this problem. Compared with the conventional gas cooling method, C-CO2 endothermic reaction method can significantly enhance the heat transfer in the crystal at the m-c interface. It was found that the heat transfer is more enhanced with a chemical reaction of smaller activation energy, and the m-c interface becomes flatter. The influence of the carbon concentration in the chemical reactive gas flow on the heat removal in the crystal at the m-c interface is also investigated. The cooling effect is significantly increased with the increase in the carbon concentration when it is small. However, when the carbon concentration in the reactive gas is high, the cooling effect just increases slightly. The research demonstrates that the proposed chemical endothermic reaction is a promising cooling technique to be applied in CZ-Si crystal growth with large size/high pulling rate.

  9. Silk fibroin/sodium alginate fibrous hydrogels regulated hydroxyapatite crystal growth.

    Science.gov (United States)

    Ming, Jinfa; Jiang, Zhijuan; Wang, Peng; Bie, Shiyu; Zuo, Baoqi

    2015-06-01

    Use of organic templates for controlling the growth of inorganic crystals is one of the research topics in biomimetic field. In particular, oriented growth of hydroxyapatite (HAp) in organic fibrous matrix is provided a new view angle to study biomineralization of bone and its potential biomedical applications. The crystallization of HAp in fibrous hydrogels could mimic such biomineralization. In this paper, we report HAp nanorod crystal synthesized successfully by a biomimetic method using calcium chloride and ammonium dihydrogen phosphate as reagents in the presence of silk fibroin/sodium alginate (SF/SA) fibrous hydrogels. The effects of influence factors such as mineral times, pH, and temperature on controlling HAp nanorod crystals are discussed. The elongated HAp nanorods with rectangular column are grown with the increase of mineral times in biomimetic process. By changing pH, HAp nanorod crystals are obtained at alkaline condition in fibrous hydrogels. Moreover, compared to other temperatures, rod-shaped HAp crystals were formed at 20°C. The results imply this to be an effective method for preparing HAp crystals with controllable morphology for bone repair application. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Solution-mediated growth of NBA-ZSM-5 crystals retarded by gel entrapment

    Science.gov (United States)

    Aguilar-Mamani, Wilson; Akhtar, Farid; Hedlund, Jonas; Mouzon, Johanne

    2018-04-01

    The synthesis of flat tablet-shaped ZSM-5 crystals from a gel using metakaolin as aluminosilicate source and n-butyl amine as structure directing agent was investigated. The evolution inside the solid phase was characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetry and mass spectrometry. A kinetic study indicated that the nucleation of the majority crystals occurred concurrently with the formation of the gel upon heating the starting liquid suspension. Microstructural evidences undeniably showed that the gel precipitated on ZSM-5 crystals and mineral impurities originating from kaolin. As a result, crystal growth was retarded by gel entrapment, as indicated by the configuration and morphology of the embedded crystals. The results presented herein are harmonized with a solution-mediated nucleation and growth mechanism. Our observations differ from the autocatalytic model that suggests that the nuclei rest inside the gel until released when the gel is consumed. Our results show instead that it is crystals that formed in an early stage before entrapment inside the gel that rest inside the gel until exposed at the gel surface. These results illustrate the limitation of the classical method used in the field to determine nucleation profiles when the crystals become trapped inside the gel.

  11. Growth of protein crystals under very small gravity environment. Bisho juryoku kankyoka deno tanpakushitsu kessho seicho

    Energy Technology Data Exchange (ETDEWEB)

    Aibara, S. (Kyoto University, Kyoto (Japan). Faculty of Engineering)

    1994-04-05

    This paper describes influence of very small gravity in space on growth of protein crystals and its future prospect based on the results of the past three space experiments. Protein crystals under very small gravity in space grow by only mutual actions among protein molecules because precipitation and convection of protein molecules in aqueous solution are suppressed. Further, because the crystal nucleus generation process reaches a rate controlling stage in the crystal growth, the crystals grow taking longer time than on the ground. However, the crystal nuclei would not move much in the aqueous solution and grow in situ, hence it is estimated that monocrystals with good crystallinity can be obtained. An experiment utilizing a space shuttle has performed crystallization at 20[degree]C for seven days. Test samples included lysozyme in chicken egg white, myoglobin in horse skeleton muscle, pseudomonas [omega]-aminotransferases, human insulin, and peroxidase in soil bacteria. High quality monocrystals with little mosaics can be obtained under very small gravity in space. 22 refs., 4 figs., 3 tabs.

  12. Growth, crystal structure, spectral properties and laser performance of Yb3+:NaLu(MoO4)2 crystal

    International Nuclear Information System (INIS)

    Yu, Yi; Zhang, Lizhen; Huang, Yisheng; Lin, Zhoubin; Wang, Guofu

    2013-01-01

    A double molybdate Yb 3+ :NaLu(MoO 4 ) 2 crystal was successfully grown from a flux of Na 2 Mo 2 O 7 by the top-seeded solution growth method, for the first time to our knowledge. The crystal belongs to the tetragonal system with space group I4 1 /a, and the unit-cell parameters are a = b = 5.159 Å, c = 11.246 Å. Na and Lu atoms co-occupy the same lattice site, which leads to the disordered structure of NaLu(MoO 4 ) 2 crystal. The thermal expansion coefficients of the crystal are 1.35 × 10 −5 K −1 along the c-axis, and 1.01 × 10 −5 K −1 along the a-axis. The full-width at half-maximum of the emission bands are 67 nm for the σ-polarization and 50 nm for the π-polarization at about 1020 nm. The maximum emission cross-sections for the σ- and π-polarizations are 2.79 × 10 −20 cm 2 and 2.94 × 10 −20 cm 2 , respectively. 0.3 W output power at 1025 nm was obtained at an absorbed pump power of 1.7 W, with a slope efficiency of 24%. (paper)

  13. Growth, crystal structure, spectral properties and laser performance of Yb3+:NaLu(MoO4)2 crystal

    Science.gov (United States)

    Yu, Yi; Zhang, Lizhen; Huang, Yisheng; Lin, Zhoubin; Wang, Guofu

    2013-10-01

    A double molybdate Yb3+:NaLu(MoO4)2 crystal was successfully grown from a flux of Na2Mo2O7 by the top-seeded solution growth method, for the first time to our knowledge. The crystal belongs to the tetragonal system with space group I41/a, and the unit-cell parameters are a = b = 5.159 Å, c = 11.246 Å. Na and Lu atoms co-occupy the same lattice site, which leads to the disordered structure of NaLu(MoO4)2 crystal. The thermal expansion coefficients of the crystal are 1.35 × 10-5 K-1 along the c-axis, and 1.01 × 10-5 K-1 along the a-axis. The full-width at half-maximum of the emission bands are 67 nm for the σ-polarization and 50 nm for the π-polarization at about 1020 nm. The maximum emission cross-sections for the σ- and π-polarizations are 2.79 × 10-20 cm2 and 2.94 × 10-20 cm2, respectively. 0.3 W output power at 1025 nm was obtained at an absorbed pump power of 1.7 W, with a slope efficiency of 24%.

  14. Crystal nucleation and dendrite growth of metastable phases in undercooled melts

    International Nuclear Information System (INIS)

    Herlach, Dieter

    2011-01-01

    Research highlights: → Homogenous nucleation. → Effects of convection on dendrite growth kinetics. → Description of disorder trapping validated by experiment. - Abstract: An undercooled melt possesses an enhanced free enthalpy that opens up the possibility to crystallize metastable crystalline solids in competition with their stable counterparts. Crystal nucleation selects the crystallographic phase whereas the growth dynamics controls microstructure evolution. We apply containerless processing techniques such as electromagnetic and electrostatic levitation to containerlesss undercool and solidify metallic melts. Owing to the complete avoidance of heterogeneous nucleation on container-walls a large undercooling range becomes accessible with the extra benefit that the freely suspended drop is direct accessible for in situ observation of crystallization far away from equilibrium. Results of investigations of maximum undercoolability on pure zirconium are presented showing the limit of maximum undercoolability set by the onset of homogeneous nucleation. Rapid dendrite growth is measured as a function of undercooling by a high-speed camera and analysed within extended theories of non-equilibrium solidification. In such both supersaturated solid solutions and disordered superlattice structure of intermetallics are formed at high growth velocities. A sharp interface theory of dendrite growth is capable to describe the non-equilibrium solidification phenomena during rapid crystallization of deeply undercooled melts. Eventually, anomalous growth behaviour of Al-rich Al-Ni alloys is presented, which may be caused by forced convection.

  15. Epitaxial crystal growth by sputter deposition: Applications to semiconductors. Part 2

    International Nuclear Information System (INIS)

    Greene, J.E.

    1984-01-01

    The understanding of the physics of ion-surface interactions has progressed sufficiently to allow sputter depositinn to be used as a crystal growth technique for depositing a wide variety of single crystal elemental, compound, alloy, and superlattice semiconductors. In many cases, films with essentially bulk values of carrier concentrations and mobilities have been obtained. The controlled use of low energy particle bombardment of the growing film during sputter deposition has been shown to affect all stages of crystal growth ranging from adatom mobilities and nucleation kinetics to elemental incorporation probabilities. Such effects provide inherent advantages for sputter deposition over other vapor phase techniques for the low temperature growth of compound and alloy semiconductors and are essential in allowing the growth of new and unique single crystal metastable semiconductors. Part 1 of this review includes sections on experimental techniques, the physics of ion-surface interactions, and ion bombardment effects on film nucleation and growth, while Part 2 presents a discussion of recent results in the growth of elemental, III-V, II-VI, IV-VI, metastable, and other compound semiconductors

  16. In Situ Determination of Thermal Profiles during Czochralski Silicon Crystal Growth by an Eddy Current Technique.

    Science.gov (United States)

    Choe, Kwang Su.

    An eddy current testing method was developed to continuously monitor crystal growth process and determine thermal profiles in situ during Czochralski silicon crystal growth. The work was motivated by the need to improve the quality of the crystal by controlling thermal gradients and annealing history over the growth cycle. The experimental concept is to monitor intrinsic electrical conductivities of the growing crystal and deduce temperature values from them. The experiments were performed in a resistance-heated Czochralski puller with a 203 mm (8 inch) diameter crucible containing 6.5 kg melt. The silicon crystals being grown were about 80 mm in diameter and monitored by an encircling sensor operating at three different test frequencies (86, 53 and 19 kHz). A one-dimensional analytical solution was employed to translate the detected signals into electrical conductivities. In terms of experiments, the effects of changes in growth condition, which is defined by crystal and crucible rotation rates, crucible position, pull rate, and hot-zone configuration, were investigated. Under a given steady-state condition, the thermal profile was usually stable over the entire length of crystal growth. The profile shifted significantly, however, when the crucible rotation rate was kept too high. As a direct evidence to the effects of melt flow on heat transfer process, a thermal gradient minimum was observed about the crystal/crucible rotation combination of 20/-10 rpm cw. The thermal gradient reduction was still most pronounced when the pull rate or the radiant heat loss to the environment was decreased: a nearly flat axial thermal gradient was achieved when either the pull rate was halved or the height of the exposed crucible wall was effectively doubled. Under these conditions, the average axial thermal gradient along the surface of the crystal was about 4-5 ^{rm o}C/mm. Regardless of growth condition, the three-frequency data revealed radial thermal gradients much larger

  17. Growth and characterization of nonlinear optical single crystals: bis ...

    Indian Academy of Sciences (India)

    Administrator

    Organic compound; growth from solution; characterization; nonlinear optical materials. 1. Introduction. Organic nonlinear optical (NLO) materials have attracted much attention due to their potential applications in telecommunication, optical switching, optical frequency conversion, THz generation, electro-optical and inte-.

  18. Development of low-cost silicon crystal growth techniques for terrestrial photovoltaic solar energy conversion

    Science.gov (United States)

    Zoutendyk, J. A.

    1976-01-01

    Because of the growing need for new sources of electrical energy, photovoltaic solar energy conversion is being developed. Photovoltaic devices are now being produced mainly from silicon wafers obtained from the slicing and polishing of cylindrically shaped single crystal ingots. Inherently high-cost processes now being used must either be eliminated or modified to provide low-cost crystalline silicon. Basic to this pursuit is the development of new or modified methods of crystal growth and, if necessary, crystal cutting. If silicon could be grown in a form requiring no cutting, a significant cost saving would potentially be realized. Therefore, several techniques for growth in the form of ribbons or sheets are being explored. In addition, novel techniques for low-cost ingot growth and cutting are under investigation.

  19. The influence of biuret on the growth kinetics of urea crystals from aqueous solutions

    Science.gov (United States)

    Davey, R.; Fila, W.; Garside, J.

    1986-12-01

    The growth kinetics of urea in the [001] and [110] directions are presented for both pure solutions and solutions containing up to 6% biuret. This impurity is formed during the synthesis of urea and acts as a powerful habit modifier. In pure solutions urea grows very quickly in the [001] but very slowly in the [110] direction. As a result long needle-like crystals are produced. In the presence of biuret [001] growth is dramatically reduced while [110] growth is virtually unaffected, so producing a crystal with a much lower length: breadth ratio. The influence of biuret is explained by the replacement of two urea molecules in the crystal lattice by a biuret molecule. The resulting disruption of the (001) face leaves insufficient NH 2-groups to satisfy the hydrogen bonding linkages.

  20. Study on influence of growth conditions on position and shape of crystal/melt interface of alkali lead halide crystals at Bridgman growth

    Czech Academy of Sciences Publication Activity Database

    Král, Robert

    2012-01-01

    Roč. 360, S1 (2012), s. 162-166 ISSN 0022-0248. [5th International Workshop on Crystal Growth Technology (IWCGT). Berlin, 26.06.2011-30.06.2011] R&D Projects: GA AV ČR KJB200100901 Institutional research plan: CEZ:AV0Z10100521 Keywords : Interfaces * morphological stability * segregation * Bridgman technique * halides Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.552, year: 2012

  1. Growth and characterization of Nd:CLNGG crystal

    Science.gov (United States)

    Shi, Z. B.; Zhang, H. J.; Wang, J. Y.; Yu, Y. G.; Wang, Z. P.; Yu, H. H.; Sun, S. Q.; Xia, H. R.; Jiang, M. H.

    2009-07-01

    The disordered laser crystal neodymium-doped calcium lithium niobium gallium garnet (Nd:CLNGG) was successfully grown by the Czochralski method. Its thermal properties, including the average linear thermal expansion coefficient, thermal diffusion coefficient, specific heat, and thermal conductivity were measured, and continuous-wave (CW) laser performance at 1.06 μm was demonstrated. The maximum power of 1.48 W was achieved with corresponding optical conversion efficiency of 12.4% and slope efficiency of 16.2%.

  2. Crystal growth and evaluation of silicon for VLSI and ULSI

    CERN Document Server

    Eranna, Golla

    2014-01-01

    PrefaceAbout the AuthorIntroductionSilicon: The SemiconductorWhy Single CrystalsRevolution in Integrated Circuit Fabrication Technology and the Art of Device MiniaturizationUse of Silicon as a SemiconductorSilicon Devices for Boolean ApplicationsIntegration of Silicon Devices and the Art of Circuit MiniaturizationMOS and CMOS Devices for Digital ApplicationsLSI, VLSI, and ULSI Circuits and ApplicationsSilicon for MEMS ApplicationsSummaryReferencesSilicon: The Key Material for Integrated Circuit Fabrication TechnologyIntroductionPreparation of Raw Silicon MaterialMetallurgical-Grade SiliconPuri

  3. Crystal growth kinetics in undercooled melts of pure Ge, Si and Ge-Si alloys

    Science.gov (United States)

    Herlach, Dieter M.; Simons, Daniel; Pichon, Pierre-Yves

    2018-01-01

    We report on measurements of crystal growth dynamics in semiconducting pure Ge and pure Si melts and in Ge100-xSix (x = 25, 50, 75) alloy melts as a function of undercooling. Electromagnetic levitation techniques are applied to undercool the samples in a containerless way. The growth velocity is measured by the utilization of a high-speed camera technique over an extended range of undercooling. Solidified samples are examined with respect to their microstructure by scanning electron microscopic investigations. We analyse the experimental results of crystal growth kinetics as a function of undercooling within the sharp interface theory developed by Peter Galenko. Transitions of the atomic attachment kinetics are found at large undercoolings, from faceted growth to dendrite growth. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'.

  4. Crystal growth kinetics in undercooled melts of pure Ge, Si and Ge-Si alloys.

    Science.gov (United States)

    Herlach, Dieter M; Simons, Daniel; Pichon, Pierre-Yves

    2018-02-28

    We report on measurements of crystal growth dynamics in semiconducting pure Ge and pure Si melts and in Ge 100- x Si x ( x  = 25, 50, 75) alloy melts as a function of undercooling. Electromagnetic levitation techniques are applied to undercool the samples in a containerless way. The growth velocity is measured by the utilization of a high-speed camera technique over an extended range of undercooling. Solidified samples are examined with respect to their microstructure by scanning electron microscopic investigations. We analyse the experimental results of crystal growth kinetics as a function of undercooling within the sharp interface theory developed by Peter Galenko. Transitions of the atomic attachment kinetics are found at large undercoolings, from faceted growth to dendrite growth.This article is part of the theme issue 'From atomistic interfaces to dendritic patterns'. © 2018 The Author(s).

  5. Atomic force microscopy studies on growth mechanisms of LAP crystals grown in solution containing excessive amount of L-arginine

    International Nuclear Information System (INIS)

    Geng, Y.L.; Xu, D.; Sun, D.L.; Du, W.; Liu, H.Y.; Zhang, G.H.; Wang, X.Q.

    2005-01-01

    Atomic force microscopy (AFM) has been used to investigate the growth mechanisms of the L-arginine phosphate monohydrate (LAP) crystal grown from the aqueous solution containing excessive amount of L-arginine molecules. Under this condition, the LAP crystals grow by both 2D nucleation mechanism and spiral dislocation mechanism. 2D nucleation growth is the intrinsical growth mechanism owing to the crystal structure of LAP. The spiral growth mechanism probably results from the distortion of the crystal lattices produced by the LA n P unit or separated L-arginine molecule. Pinning points of impurities and curved step type induced by them are also explored

  6. Control of heat transfer in continuous-feeding Czochralski-silicon crystal growth with a water-cooled jacket

    Science.gov (United States)

    Zhao, Wenhan; Liu, Lijun

    2017-01-01

    The continuous-feeding Czochralski method is an effective method to reduce the cost of single crystal silicon. By promoting the crystal growth rate, the cost can be reduced further. However, more latent heat will be released at the melt-crystal interface under a high crystal growth rate. In this study, a water-cooled jacket was applied to enhance the heat transfer at the melt-crystal interface. Quasi-steady-state numerical calculation was employed to investigate the impact of the water-cooled jacket on the heat transfer at the melt-crystal interface. Latent heat released during the crystal growth process at the melt-crystal interface and absorbed during feedstock melting at the feeding zone was modeled in the simulations. The results show that, by using the water-cooled jacket, heat transfer in the growing crystal is enhanced significantly. Melt-crystal interface deflection and thermal stress increase simultaneously due to the increase of radial temperature at the melt-crystal interface. With a modified heat shield design, heat transfer at the melt-crystal interface is well controlled. The crystal growth rate can be increased by 20%.

  7. Segregation of Ge in B and Ge codoped Czochralski-Si crystal growth

    International Nuclear Information System (INIS)

    Arivanandhan, Mukannan; Gotoh, Raira; Fujiwara, Kozo; Uda, Satoshi; Hayakawa, Yasuhiro

    2015-01-01

    Highlights: • Effective segregation of Ge in B and Ge codoped Czochralski-Si crystal growth was analyzed. • The equilibrium segregation coefficient of Ge was calculated. • The experimentally results were analytically analyzed using partitioning theory. - Abstract: The segregation of Ge in B and Ge codoped Czochralski (CZ)-Si crystal growth was investigated. The concentration of Ge in heavily Ge codoped CZ-Si was measured by electron probe micro analysis (EPMA) and X-ray fluorescence spectroscopy. The effective segregation coefficient of Ge (k eff ) was calculated by fitting the EPMA data to the normal freezing equation, and by taking the logarithmic ratio of the Ge concentrations at the seed and tail of the ingots (top to bottom approach). The k eff of Ge increased from 0.30 to 0.55, when the initial Ge concentration in the Si melt (C L(o) Ge ) was increased from 3 × 10 19 to 3 × 10 21 cm −3 . To avoid cellular growth, the crystal pulling rate was decreased for heavily Ge codoped crystal growth (C L(o) Ge > 3 × 10 20 cm −3 ). The equilibrium segregation coefficient (k 0 ) of Ge was calculated by partitioning theory, and was smaller than the experimentally estimated k eff . The variation of k eff from k 0 was discussed based on Ge clustering in the heavily Ge codoped crystal, which led to changes in the bonding and strain energies caused by the incorporation of Ge into Si

  8. Growth kinetics of protein single crystals in the gel acupuncture technique

    Science.gov (United States)

    García-Ruiz, Juan Manuel; Moreno, Abel

    1997-07-01

    The growth of single crystals of tetragonal HEW lysozyme and thaumatin I into glass capillaries was monitored by time lapse video-microscopy. The crystals were obtained by unidirectional transport of the precipitating agent through capillaries of internal diameter ranging from 0.2 to 1.2 mm, using the gel acupuncture technique. For crystals growing from true protein solutions, the measured average growth rates varies with capillary diameter from 1.7 to 3.7 Å/s for thaumatin and from 2.8 to 22 Å/s for lysozyme. The measured average growth rates for crystals growing into gelled protein solutions were 1.8 Å/s for thaumatin and 2.5 Å/s for lysozyme. The trend in the variation of the growth rate with time is similar and suggests that, for capillaries with internal radius lower than 0.8 mm, diffusion dominates the global mass transport control. However, the existence of convection rolls near the crystal-solution interface and close to zones with high density gradient cannot be discarded.

  9. Contribution to the study of the role of diffusion in the growth of crystals from solution

    International Nuclear Information System (INIS)

    Quivy, M.

    1965-12-01

    In the case of the two-dimensional growth of crystals from solution, the concentration distribution could be explained on the basis of Fick diffusion equation. The limiting conditions are defined in a satisfactory way, and the curves of equal concentration in the solution surrounding the crystal are calculated using a resistance network device. These curves are similar to the observed interference fringes. The limiting conditions are different according as to whether the type of crystal growth is regular or dendritic. In this work the growth rate of the crystal faces in solution has been measured for various substances. These direct measurements were carried out using a micrometric eye-piece and chrono-photographs. The interferential method using polarized light has been used for determining the concentration distribution in the neighbourhood of the crystal; it was thereby possible, knowing the diffusion coefficient, to calculate the growth rate and to observe the existence of a disagreement, of the order of two, with the direct measurements. This discrepancy can even attain a value of ten in the case of very soluble substances; these latter have been studied by R. ITTI. (author) [fr

  10. Studies on crystal growth, vibrational and optical properties of organic nonlinear optical crystal: p-Aminoazobenzene

    Science.gov (United States)

    Eazhilarasi, G.; Nagalakshmi, R.; Krishnakumar, V.

    2008-11-01

    p-Aminoazobenzene ( p-AAZB), an organic nonlinear optical (NLO) crystal having good optical quality has been grown by slow evaporation solution technique using ethanol as a solvent. Solubility studies were performed at different temperatures. The structural characterization of the grown crystals was carried out by X-ray diffraction. Group theoretical analysis was carried out to calculate the number of modes of vibration. The lowering of the wave numbers of azo group suggests the existence of strong intermolecular N-H⋯H hydrogen bonding. This has been analysed based on the vibrational spectral features. Optical absorption studies show the effective transmission in the entire UV-vis region. The second harmonic generation results show the suitability of this material for NLO applications.

  11. Mediation of calcium oxalate crystal growth on human kidney epithelial cells with different degrees of injury

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Shen [Graduate School of Southern Medical University, Guangzhou 510515 (China); Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Su Zexuan, E-mail: suz2008@126.com [The First Affiliated Hospital, Jinan University, Guangzhou 510632 (China); Yao Xiuqiong; Peng Hua; Deng Suiping [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Ouyang Jianming, E-mail: toyjm@jnu.edu.cn [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China)

    2012-05-01

    The current study examined the role of injured human kidney tubular epithelial cell (HKC) in the mediation of formation of calcium oxalate (CaOxa) crystals by means of scanning electronic microscopy and X-ray diffraction. HKC was injured using different concentrations of H{sub 2}O{sub 2}. Cell injury resulted in a significant decrease in cell viability and superoxide dismutase (SOD) concentration and an increase in the level of malondialdehyde (MDA) and expression of osteopontin (OPN). Injured cells not only promote nucleation and aggregation of CaOxa crystals, but also induce the formation of calcium oxalate monohydrate (COM) crystals that strongly adhere to cells. These results imply that injured HKCs promote stone formation by providing more nucleating sites for crystals, promoting the aggregation of crystals, and inducing the formation of COM crystals. - Graphical abstract: Injured cells promote nucleation and aggregation of CaOxa crystals, induce the formation of calcium oxalate monohydrate (COM) crystals. Highlights: Black-Right-Pointing-Pointer A direct nucleation and growth of CaOxa crystals on both normal and injured cells. Black-Right-Pointing-Pointer Stronger green fluorescence, i.e. OPN expression, was seen on the injury cell surface Black-Right-Pointing-Pointer Injured cells promote nucleation and aggregation of CaOxa crystals. Black-Right-Pointing-Pointer Injured cells induce the formation of calcium oxalate monohydrate crystals. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} decrease cell viability in a dose-dependent manner at 0.1-1 mmol/L.

  12. Effect of crucible and crystal rotations on the convexity and the thermal stress in large size sapphire crystals during Czochralski growth

    Science.gov (United States)

    Nguyen, Tran Phu; Hsieh, Yao-Te; Chen, Jyh-Chen; Hu, Chieh; Nguyen, Huy Bich

    2017-06-01

    In this study, the effect of the temperature and flow fields generated by the rotation of the crucible and the crystal on the convexity of a c-axis, large-diameter sapphire crystal during the Czochralski growth process is investigated numerically. The thermal stress distributions in different sizes of crystal are also considered. The computational results show that the convexity and the thermal stress of the crystal are strongly dependent on the crucible and crystal rotation rates. The counter rotation between the crucible and the crystal results in a flatter crystal-melt interface, compared to the case of no crucible rotation or crystal rotation. Maximum thermal stress occurs at the highest curvature of the crystal-melt interface which appears near the center of the growing crystal, and the value is directly proportional to the crystal's size. Moreover, there is a significant decrease in the von Mises stress for the crystal-melt interface with lower convexity due to a reduction in the temperature gradient in the radial direction along the interface. As the crystal length gets larger, the maximum von Mises stress rapidly reduces.

  13. (Li1−xFexOHFeSe Superconductors: Crystal Growth, Structure, and Electromagnetic Properties

    Directory of Open Access Journals (Sweden)

    Guo-Yong Zhang

    2017-06-01

    Full Text Available This review focuses on the growth of high-quality (Li1−xFexOHFeSe single crystals by a hydrothermal method using floating-zone-grown AxFe2−ySe2 (A = K, Rb, and Cs as precursors. The structure, superconductivity, and magnetic behavior of the obtained crystals are highly influenced by the growth conditions, such as time, temperature, and composition. A phase diagram with temperature against the c-lattice constant is summarized including the antiferromagnetic spin density wave, superconducting, and paramagnetic phases.

  14. Dual Effect of the Cubic Ag₃PO₄ Crystal on Pseudomonas syringae Growth and Plant Immunity

    Directory of Open Access Journals (Sweden)

    Mi Kyung Kim

    2016-04-01

    Full Text Available We previously found that the antibacterial activity of silver phosphate crystals on Escherichia coli depends on their structure. We here show that the cubic form of silver phosphate crystal (SPC can also be applied to inhibit the growth of a plant-pathogenic Pseudomonas syringae bacterium. SPC pretreatment resulted in reduced in planta multiplication of P. syringae. Induced expression of a plant defense marker gene PR1 by SPC alone is suggestive of its additional plant immunity-stimulating activity. Since SPC can simultaneously inhibit P. syringae growth and induce plant defense responses, it might be used as a more effective plant disease-controlling agent.

  15. Synthesis and growth of single crystals of PrCl3

    International Nuclear Information System (INIS)

    Pei, Jen Shieh.

    1984-01-01

    An efficient method for growth of high optical quality single crystals of PrCl 3 . The method consists in careful drying of the hydrated chloride, PrCl 3 . 7H 2 O, with a protective atmosphere of anhydrous HCl and Ar. A subsequent growth was done by the zone melting technique. The hydrated chloride had prepared from dissolution of the oxide Pr 6 O 11 in hydrochloric acid. The grown crystals had characterized fluorescence and x-ray diffraction measurements. (Author) [pt

  16. Direct growth of self-crystallized graphene and graphite nanoballs with Ni vapor-assisted growth: From controllable growth to material characterization

    Science.gov (United States)

    Yen, Wen-Chun; Chen, Yu-Ze; Yeh, Chao-Hui; He, Jr-Hau; Chiu, Po-Wen; Chueh, Yu-Lun

    2014-01-01

    A directly self-crystallized graphene layer with transfer-free process on arbitrary insulator by Ni vapor-assisted growth at growth temperatures between 950 to 1100°C via conventional chemical vapor deposition (CVD) system was developed and demonstrated. Domain sizes of graphene were confirmed by Raman spectra from ~12 nm at growth temperature of 1000°C to ~32 nm at growth temperature of 1100°C, respectively. Furthermore, the thickness of the graphene is controllable, depending on deposition time and growth temperature. By increasing growth pressure, the growth of graphite nano-balls was preferred rather than graphene growth. The detailed formation mechanisms of graphene and graphite nanoballs were proposed and investigated in detail. Optical and electrical properties of graphene layer were measured. The direct growth of the carbon-based materials with free of the transfer process provides a promising application at nanoelectronics. PMID:24810224

  17. New Crystal-Growth Methods for Producing Lattice-Matched Substrates for High-Temperature Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Boatner, L.A.

    2008-06-24

    This effort addressed the technical problem of identifying and growing, on a commercial scale, suitable single-crystal substrates for the subsequent deposition of epitaxial thin films of high temperature semiconductors such as GaN/AlN. The lack of suitable lattice-matched substrate materials was one of the major problem areas in the development of semiconducting devices for use at elevated temperatures as well as practical opto-electronic devices based on Al- and GaN technology. Such lattice-matched substrates are necessary in order to reduce or eliminate high concentrations of defects and dislocations in GaN/AlN and related epitaxial thin films. This effort concentrated, in particular, on the growth of single crystals of ZnO for substrate applications and it built on previous ORNL experience in the chemical vapor transport growth of large single crystals of zinc oxide. This combined expertise in the substrate growth area was further complemented by the ability of G. Eres and his collaborators to deposit thin films of GaN on the subject substrates and the overall ORNL capability for characterizing the quality of such films. The research effort consisted of research on the growth of two candidate substrate materials in conjunction with concurrent research on the growth and characterization of GaN films, i.e. the effort combined bulk crystal growth capabilities in the area of substrate production at both ORNL and the industrial partner, Commercial Crystal Growth Laboratories (CCL), Naples, Florida, with the novel thin-film deposition techniques previously developed in the ORNL SSD.

  18. The Way towards Ultrafast Growth of Single-Crystal Graphene on Copper.

    Science.gov (United States)

    Zhang, Zhihong; Xu, Xiaozhi; Qiu, Lu; Wang, Shaoxin; Wu, Tianwei; Ding, Feng; Peng, Hailin; Liu, Kaihui

    2017-09-01

    The exceptional properties of graphene make it a promising candidate in the development of next-generation electronic, optoelectronic, photonic and photovoltaic devices. A holy grail in graphene research is the synthesis of large-sized single-crystal graphene, in which the absence of grain boundaries guarantees its excellent intrinsic properties and high performance in the devices. Nowadays, most attention has been drawn to the suppression of nucleation density by using low feeding gas during the growth process to allow only one nucleus to grow with enough space. However, because the nucleation is a random event and new nuclei are likely to form in the very long growth process, it is difficult to achieve industrial-level wafer-scale or beyond (e.g. 30 cm in diameter) single-crystal graphene. Another possible way to obtain large single-crystal graphene is to realize ultrafast growth, where once a nucleus forms, it grows up so quickly before new nuclei form. Therefore ultrafast growth provides a new direction for the synthesis of large single-crystal graphene, and is also of great significance to realize large-scale production of graphene films (fast growth is more time-efficient and cost-effective), which is likely to accelerate various graphene applications in industry.

  19. Phosphorus diffusion in float zone silicon crystal growth

    DEFF Research Database (Denmark)

    Larsen, Theis Leth

    2000-01-01

    , including centrifugal, buoyancy, thermocapillary and electromagnetic forces, is used to determine flow field, after the phase boundaries have been determined, by the heat transfer model. A finite element model for calculating dopant transport, using the calculated unsteady flow field, has been developed.......8'' conguration. The heat transfer calculations of the same three congurations, yields the global temperature field, from which temperature gradients are determined. The heat transfer model is furthermore expanded to study convective cooling of the crystal from natural convection in the pressurized surrounding...... boundary layers at the lower phase boundaries. The dopant concentrations, at the lower phase boundaries, are used to determine radial resistivity profies, which with fair agreement are compared to measurements. Simulations of defect transport are conducted for both of the 4'', as well as the 0...

  20. Bulk Group-III Nitride Crystal Growth in Supercritical Ammonia-Sodium Solutions

    Science.gov (United States)

    Griffiths, Steven Herbert

    Gallium nitride (GaN) and its alloys with indium nitride (InGaN) and aluminum nitride (AlGaN), collectively referred to as Group-III Nitride semiconductors, have enabled white solid-state lighting (SSL) sources and power electronic devices. While these technologies have already made a lasting, positive impact on society, improvements in design and efficiency are anticipated by shifting from heteroepitaxial growth on foreign substrates (such as sapphire, Si, SiC, etc.) to homoepitaxial growth on native, bulk GaN substrates. Bulk GaN has not supplanted foreign substrate materials due to the extreme conditions required to achieve a stoichiometric GaN melt (temperatures and pressures in excess of 2200°C and 6 GPa, respectively). The only method used to produce bulk GaN on an industrial scale is hydride vapor phase epitaxy (HVPE), but the high cost of gaseous precursors and relatively poor crystal quality have limited the adoption of this technology. A solution growth technique known as the ammonothermal method has attracted interest from academia and industry alike for its ability to produce bulk GaN boules of exceedingly high crystal quality. The ammonothermal method employs supercritical ammonia (NH3) solutions to dissolve, transport, and crystallize GaN. However, ammonothermal growth pressures are still relatively high (˜200 MPa), which has thus far prevented the acquisition of fundamental crystal growth knowledge needed to efficiently (i.e. through data-driven approaches) advance the field. This dissertation focused on addressing the gaps in the literature through two studies employing in situ fluid temperature analysis. The first study focused on identifying the solubility of GaN in supercritical NH3-Na solutions. The design and utilization of in situ and ex situ monitoring equipment enabled the first reports of the two-phase nature of supercritical NH3-Na solutions, and of Ga-alloying of Ni-containing autoclave components. The effects of these error sources on

  1. Simulation of V/G During Φ450 mm Czochralski Grown Silicon Single Crystal Growth Under the Different Crystal and Crucible Rotation Rates

    Directory of Open Access Journals (Sweden)

    Guan X J

    2016-01-01

    Full Text Available For discovering the principle of processing parameter combination for the stable growth and better wafer quality of Φ450 mm Czochralski grown silicon single crystal (shortly called Cz silicon crystal, the effects of crystal rotation rate and crucible one on the V/G ratio were simulated by using CGSim software. The results show that their effect laws on the V/G ratio for Φ450 mm Cz silicon crystal growth are some different from that for Φ200 mm Cz silicon one, and the effects of crucible rotation rate are relatively smaller than that of crystal one and its increasing only makes the demarcation point between two regions with different V/G ratio variations outward move along radial direction, and it promotes the wafer quality to weaken crystal rotation rate and strengthen crucible one.

  2. Recent developments in Liquid Phase Electroepitaxial growth of bulk crystals under magnetic field

    Science.gov (United States)

    Dost, Sadik; Lent, Brian; Sheibani, Hamdi; Liu, Yongcai

    2004-05-01

    This review article presents recent developments in Liquid Phase Electroepitaxial (LPEE) growth of bulk single crystals of alloy semiconductors under an applied static magnetic field. The growth rate in LPEE is proportional to the applied electric current. However, at higher electric current levels the growth becomes unstable due to the strong convection occurring in the liquid zone. In order to address this problem, a significant body of research has been performed in recent years to suppress and control the natural convection for the purpose of prolonging the growth process to grow larger crystals. LPEE growth experiments show that the growth rate under an applied static magnetic field is also proportional and increases with the field intensity level. The modeling of LPEE growth under magnetic field was also the subject of interest. Two-dimensional mathematical models developed for the LPEE growth process predicted that the natural convection in the liquid zone would be suppressed almost completely with increasing the magnetic field level. However, experiments and also three-dimensional models have shown that there is an optimum magnetic field level below which the growth process is stable and the convection in the liquid zone is suppressed, but above such a field level the convective flow becomes very strong and leads to unstable growth with unstable interfaces. To cite this article: S. Dost et al., C. R. Mecanique 332 (2004).

  3. Non-carbon induction furnace

    Science.gov (United States)

    Holcombe, C.E.; Masters, D.R.; Pfeiler, W.A.

    1984-01-06

    The present invention is directed to an induction furnace for melting and casting highly pure metals and alloys such as uranium and uranium alloys in such a manner as to minimize contamination of the melt by carbon derived from the materials and the environment within the furnace. The subject furnace is constructed of non-carbon materials and is housed within a conventional vacuum chamber. The furnace comprises a ceramic oxide crucible for holding the charge of metal or alloys. The heating of the crucible is achieved by a plasma-sprayed tungsten susceptor surrounding the crucible which, in turn, is heated by an rf induction coil separated from the susceptor by a cylinder of inorganic insulation. The furnace of the present invention is capable of being rapidly cycled from ambient temperatures to about 1650/sup 0/C for effectively melting uranium and uranium alloys without the attendant carbon contamination problems previously encountered when using carbon-bearing furnace materials.

  4. Microdefects revealed by X-ray diffusion scattering in Czochralski-growth dislocation-free silicon single crystals

    International Nuclear Information System (INIS)

    Bublik, B.T.; Zotov, N.M.

    1997-01-01

    Microdefects in the regions of Si crystals having different thermal history defined by growth conditions was studied by the X-ray diffuse scattering method on a triple crystal X-ray diffractometer. It was shown that in such crystals the microdefects with positive strength are prevalent. However, between the above indicated regions the defects with the strength of opposite sign prevail

  5. Simulation and characterization of the crystal growth by photoemission

    International Nuclear Information System (INIS)

    Fazouan, N.

    1994-01-01

    In this thesis, we argue in favour of photoemission as an in-situ characterization tool for the homo-epitaxial growth of GaAs. The first part, is concerned with the interpretation of the origin of the photoemission oscillations as first observed by J.N. Eckstein and al during MBE growth of GaAs. To study this effect, two approaches have been used. These approaches are based on reaction surface and roughness observations to study the growth mode. They associate the photoemission current with the presence of uncovered gallium adatoms, i.e. those which do not have an arsenic atom above them. The first approach is based on chemical rate theory, whereas the second is based on an atomistic simulation of GaAs homo-epitaxy. This last approach introduces the notion of interlayer migration processes and uses a Monte Carlo technique to look at the temporal evolution of the configuration and hence the morphology. It is shown with these two approaches that the photoemission current has similar characteristics as to those of RHEED, c.g.the same oscillation period. The results obtained have shown the relationship between the photoemission oscillations amplitude and the growth mode which are determined by the mechanisms of absorption and diffusion of gallium atoms and arsenic atoms of molecules. Finally, the study of the effect of the surface reactions shows the importance of these in the case where arsenic is supplied in molecular form (As 2 ). The last part concerns the experimental measurements at the threshold photoemission current during epitaxial growth of GaAs by metal-organic vapour phase epitaxy (MOVPE). The objective of this experimental study is to test the good running of the photo-assisted MOVPE low pressure system and to study the possibilities offered by this as an in-situ diagnostic tool for MOVPE. (author). 101 refs., 80 figs., 6 tabs

  6. Influence of controlling vibrations on heat transfer in floating zone crystal growth*

    Science.gov (United States)

    Fedyushkin, A. I.

    The crystal growth processes of monocrystals are strongly vibrational sensitive systems and in particular it concerns to a floating zone method as presence of a free surface and two fronts of crystallization and melting that aggravate it The given work is devoted to numerical investigations of the influence of controlling vibrations on heat transfer during crystal growth by floating zone technique Normal and weightless environment conditions are considered Mathematical simulation is performed on the numerical solutions of basis unsteady Navier-Stokes equations for incompressible fluid flows and energy equation 2D axisymmetric geometry was used in model Marangoni convection and radiation condition on the curvature free surface were taken in account The calculations of the shape of a free surface of a liquid zone and influences on it of a corner of wetting force of weight and size of factor of a superficial tension are carried out The simulations of convective heat transfer for real curvature free surface of a liquid zone with and without the taking into account of the following factors parameters of radiation rotations natural and Marangoni convection and vibrations are carried out The given calculations are carried out for semiconductors melts with Prandtl number Pr 1 and for oxides Pr 1 The influence of vibrations of a crystal on melt flow and on the wide of dynamic and thermal boundary layers at melt-crystal interface is studied The action of vibrations on an enhancement of heat fluxes at the melt crystal interface is shown

  7. Temperature dependence of protein solubility-determination, application to crystallization, and growth kinetics studies

    Science.gov (United States)

    Rosenberger, Franz

    1993-01-01

    A scintillation method was developed for determinations of the temperature dependence of the solubility, and of nucleation induction times of proteins, in 50-100 mu(l) volumes of solution. Solubility data for lysozyme and horse serum albumin were obtained for various combinations of pH and precipitant concentrations. These data and the nucleation induction information were used for dynamic crystallization control, that is, for the controlled separation of nucleation and growth stages. Individual lysozyme and horse serum albumin crystals were grown in 15-20 mu(l) solution volumes contained in x-ray capillaries. The morphology and kinetics of the growth and dissolution of lysozyme in aqueous solutions with 2.5 percent NaCl and at pH = 4.5 was studied in situ with a depth resolution of 300 A (4 unit cells) by high resolution optical microscopy and digital image processing. The bulk super- or under saturation, sigma, of the solution inside a closed growth cell was controlled by temperature. The growth habit was bound by (110) and (101) faces that grew through layer spreading, although with different growth rate dependencies on supersaturation/temperature. At sigma less than 10 (obtained at higher temperatures) growth was purely kinetic ally controlled, with impurity effects (macrostep formation and kinetic hindrance) becoming significant for sigma less than 2. At sigma greater than 10 (lower temperatures), anisotropies in the interfacial kinetics were more pronounced, with interfacial kinetics and bulk transport becoming equally important to the growth morphology. Growth rates were growth history dependent. The formation of striations (layers of irregularly incorporated solution) was unambiguously correlated with growth temperature variations. Etching exposed dislocations and various high-index faces whose growth morphologies were studied during return to the steady state growth form. Growth steps were observed to originate from two-dimensional nuclei or from outcrops

  8. Improved Casting Furnace Conceptual Design

    Energy Technology Data Exchange (ETDEWEB)

    Fielding, Randall Sidney [Idaho National Lab. (INL), Idaho Falls, ID (United States); Tolman, David Donald [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-02-01

    In an attempt to ensure more consistent casting results and remove some schedule variance associated with casting, an improved casting furnace concept has been developed. The improved furnace uses the existing arc melter hardware and glovebox utilities. The furnace concept was designed around physical and operational requirements such as; a charge sized of less than 30 grams, high heating rates and minimal additional footprint. The conceptual model is shown in the report as well as a summary of how the requirements were met.

  9. Application of temperature control strategies to the growth of hen egg-white lysozyme crystals

    Science.gov (United States)

    Schall, Constance A.; Riley, Jill S.; Li, Edwin; Arnold, Edward; Wiencek, John M.

    1996-08-01

    Solubility data were combined with mass balances and growth kinetics to derive a temperature control algorithm which maintains a constant level of supersaturation. This constant supersaturation control (CSC) algorithm attempts to maximize the size of protein crystals by maintaining the growth conditions in the metastable zone. Using hen egg-white lysozyme as a model protein system, four temperature programming strategies were employed in seeded and unseeded systems: the CSC algorithm, a linear ramp derived from the CSC algorithm, isothermal 20°C, and isothermal 4°C. Both the CSC-derived linear and the CSC temperature programs yielded large, well-formed crystals which were significantly larger than crystals grown isothermally at 20 and 4°C. The isothermal 4°C program resulted in poorly formed crystals due to the high initial growth rates. The seeded systems displayed much higher levels of nucleation than the unseeded systems which is attributed to secondary nucleation. The results indicate that moderate deviations (˜ 20%) from constant supersaturation can be tolerated, while still producing large, well-formed crystals appropriate for X-ray crystallography.

  10. Single-crystal growth of Group IVB and VB carbides by the floating-zone method

    International Nuclear Information System (INIS)

    Finch, C.B.; Chang, Y.K.; Abraham, M.M.

    1989-02-01

    The floating-zone method for the growth of Group IVB and VB carbides is described and reviewed. We have systematically investigated the technique and confirmed the growth of large single crystals of TiC/sub 0.95/, ZrC/sub 0.93/, ZrC/sub 0.98/, VC/sub 0.80/, NbC/sub 0.95/, TaC/sub 0.89/. Optimal growth conditions were in the 0.5-2.0 cm/h range under 8-12 atm helium. Good crystal growth results were achieved with hot-pressed starting rods of 90-95% density, using a ''double pancake'' induction coil and a 200-kHz/100- kW rf power supply. 36 refs., 5 figs., 3 tabs

  11. Czochralski growth and topographic study of tetragonal (La,Sr)(Al,Ta)O 3 single crystals

    Science.gov (United States)

    Xiao, Jingzhong; Shao, Manjun; Tian, Yulian; Huang, Wanxia; Wang, Aihua; Yin, Shaotang

    2002-03-01

    Large tetragonal phase (La,Sr)(Al,Ta)O 3 (LSAT) crystals used as substrates for growing functional thin-film materials were successfully grown by the Czochralski method using [0 0 1] LaAlO 3 rod as seed. The crystal phase was determined by the method of powder X-ray diffraction analysis and the transmission spectrum indicates that the absorption edge of the crystal is at 270 nm while no apparent absorption peaks were found. Through the technique of environmental scanning electron microscopy and synchrotron radiation white-beam topography, the surface topography and defects were characterized, and clear and stable images of twins, micro-cracks, inclusions, grain boundaries, dislocation etch pits, and growth striations in the as-grown LSAT crystals were obtained.

  12. Synthesis, crystal growth and studies on non-linear optical property of new chalcones

    Science.gov (United States)

    Sarojini, B. K.; Narayana, B.; Ashalatha, B. V.; Indira, J.; Lobo, K. G.

    2006-09-01

    The synthesis, crystal growth and non-linear optical (NLO) property of new chalcone derivatives are reported. 4-Propyloxy and 4-butoxy benzaldehydes were made to under go Claisen-Schmidt condensation with 4-methoxy, 4-nitro and 4-phenoxy acetophenones to form corresponding chalcones. The newly synthesized compounds were characterized by analytical and spectral data. The Second harmonic generation (SHG) efficiency of these compounds was measured by powder technique using Nd:YAG laser. Among tested compounds three chalcones showed NLO property. The chalcone 1-(4-methoxyphenyl)-3-(4-propyloxy phenyl)-2-propen-1-one exhibited SHG conversion efficiency 2.7 times that of urea. The bulk crystal of 1-(4-methoxyphenyl)-3-(4-butoxyphenyl)-2-propen-1-one (crystal size 65×28×15 mm 3) was grown by slow-evaporation technique from acetone. Microhardness of the crystal was tested by Vicker's microhardness method.

  13. Electron microscopic studies on the initial process of lysozyme crystal growth

    Science.gov (United States)

    Michinomae, M.; Mochizuki, M.; Ataka, M.

    1999-02-01

    The initial process of lysozyme crystallization has been investigated by negatively stained electron microscopy. In the initial process of crystallization, two steps were distinguished by the appearance of associating protein molecules. One is the formation of the short threads, and the other the formation of the spherical structure (looks like a rice-ball). From among the mass of the rice-balls, larger structure appears. Some of them show the arrangement of molecules as a crystalline lattice. The spacing between the molecules agrees with one of the lattice constants known for the tetragonal lysozyme crystals. The rice-balls may be taken into crystals as essential growth units. Similarly, the thread-like structures may be the unit to form the rice-balls that appear in the next step.

  14. Use of anomolous thermal imaging effects for multi-mode systems control during crystal growth

    Science.gov (United States)

    Wargo, Michael J.

    1989-01-01

    Real time image processing techniques, combined with multitasking computational capabilities are used to establish thermal imaging as a multimode sensor for systems control during crystal growth. Whereas certain regions of the high temperature scene are presently unusable for quantitative determination of temperature, the anomalous information thus obtained is found to serve as a potentially low noise source of other important systems control output. Using this approach, the light emission/reflection characteristics of the crystal, meniscus and melt system are used to infer the crystal diameter and a linear regression algorithm is employed to determine the local diameter trend. This data is utilized as input for closed loop control of crystal shape. No performance penalty in thermal imaging speed is paid for this added functionality. Approach to secondary (diameter) sensor design and systems control structure is discussed. Preliminary experimental results are presented.

  15. Atomistic Simulations of Nonequilibrium Crystal-Growth Kinetics from Alloy Melts

    Science.gov (United States)

    Yang, Yang; Humadi, Harith; Buta, Dorel; Laird, Brian B.; Sun, Deyan; Hoyt, Jeffrey J.; Asta, Mark

    2011-07-01

    Nonequilibrium kinetic properties of alloy crystal-melt interfaces are calculated by molecular-dynamics simulations. The relationships between the interface velocity, thermodynamic driving force, and solute partition coefficient are computed and analyzed within the framework of kinetic theories accounting for solute trapping and solute drag. The results show a transition to complete solute trapping at high growth velocities, establish appreciable solute drag at low growth velocities, and provide insights into the nature of crystalline anisotropies and solute effects on interface mobilities.

  16. Growth of co-doped semi-insulation indium phospide crystals for X-ray detection

    Czech Academy of Sciences Publication Activity Database

    Pekárek, Ladislav; Žďánský, Karel

    2005-01-01

    Roč. 275, - (2005), e409-e413 ISSN 0022-0248. [International Conference on Crystal Growth /14./. Grenoble, 09.08.20004-12.08.2004] R&D Projects: GA AV ČR(CZ) IBS2067354 Institutional research plan: CEZ:AV0Z10100520 Keywords : growth from melt * Czochralski method * indium phosphide * semiconductor doping Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.681, year: 2005

  17. Flux Growth of Heavy Fermion LiV2O4 Single Crystals

    Science.gov (United States)

    Das, S.; Zong, X.; Niazi, A.; Johnston, D. C.

    2007-03-01

    The spinel-structure compound LiV2O4 is a rare d- electron heavy fermion. Measurements on single crystals are needed to clarify the mechanism for the heavy fermion behavior. In addition, it is known that small concentrations (< 1 mol%) of magnetic defects in the structure strongly affect the properties, and measurements on single crystals containing magnetic defects would help to understand the latter behaviors. Herein, we report growth at 950--1030 ^oC of 1 mm^3 size octahedron-shaped LiV2O4 single crystals using a self- flux technique. The magnetic susceptibility of the as-grown crystals shows a Curie-like upturn at low temperatures arising from 0.5 mol% magnetic defects within the spinel structure. After annealing at 700 ^oC, the Curie-like upturn (and magnetic defects) disappeared in some crystals, thus revealing the known intrinsic nearly temperature-independent behavior below ˜20 K@. Preliminary heat capacity measurements on as-grown crystals containing magnetic defects showed a high linear specific heat coefficient γ = 450 mJ/ (mole K^2) at 1.8 K@. Additional electronic tranport, magnetic and thermal measurements on both as-grown and annealed crystals will be presented.

  18. Solvent effects on the crystal growth structure and morphology of the pharmaceutical dirithromycin

    Science.gov (United States)

    Wang, Yuan; Liang, Zuozhong

    2017-12-01

    Solvent effects on the crystal structure and morphology of pharmaceutical dirithromycin molecules were systematically investigated using both experimental crystallization and theoretical simulation. Dirithromycin is one of the new generation of macrolide antibiotics with two polymorphic forms (Form I and Form II) and many solvate forms. Herein, six solvates of the dirithromycin, including acetonitrile, acetonitrile/water, acetone, 1-propanol, N,N-dimethylformamide (DMF) and cyclohexane, were studied. Experimentally, we crystallized the dirithromycin molecules in different solvents by the solvent evaporating method and measured the crystal structures with the X-ray diffraction (XRD). We compared these crystal structures of dirithromycin solvates and analyzed the solvent property-determined structure evolution. The solvents have a strong interaction with the dirithromycin molecule due to the formation of inter-molecular interactions (such as the hydrogen bonding and close contacts (sum of vdW radii)). Theoretically, we calculated the ideal crystal habit based on the solvated structures with the attachment growth (AE) model. The predicted morphologies and aspect ratios of dirithromycin solvates agree well with the experimental results. This work could be helpful to better understand the structure and morphology evolution of solvates controlled by solvents and guide the crystallization of active pharmaceutical ingredients in the pharmaceutical industry.

  19. Seeded growth of boron arsenide single crystals with high thermal conductivity

    Science.gov (United States)

    Tian, Fei; Song, Bai; Lv, Bing; Sun, Jingying; Huyan, Shuyuan; Wu, Qi; Mao, Jun; Ni, Yizhou; Ding, Zhiwei; Huberman, Samuel; Liu, Te-Huan; Chen, Gang; Chen, Shuo; Chu, Ching-Wu; Ren, Zhifeng

    2018-01-01

    Materials with high thermal conductivities are crucial to effectively cooling high-power-density electronic and optoelectronic devices. Recently, zinc-blende boron arsenide (BAs) has been predicted to have a very high thermal conductivity of over 2000 W m-1 K-1 at room temperature by first-principles calculations, rendering it a close competitor for diamond which holds the highest thermal conductivity among bulk materials. Experimental demonstration, however, has proved extremely challenging, especially in the preparation of large high quality single crystals. Although BAs crystals have been previously grown by chemical vapor transport (CVT), the growth process relies on spontaneous nucleation and results in small crystals with multiple grains and various defects. Here, we report a controllable CVT synthesis of large single BAs crystals (400-600 μm) by using carefully selected tiny BAs single crystals as seeds. We have obtained BAs single crystals with a thermal conductivity of 351 ± 21 W m-1 K-1 at room temperature, which is almost twice as conductive as previously reported BAs crystals. Further improvement along this direction is very likely.

  20. Synthesis, growth, structural, optical and thermal properties of a new organic salt crystal: 3-nitroanilinium trichloroacetate

    Science.gov (United States)

    Selvakumar, E.; Chandramohan, A.; Anandha Babu, G.; Ramasamy, P.

    2014-09-01

    A new organic non-linear optical salt 3-nitroanilinium trichloroacetate has been synthesized and single crystals grown by slow solvent evaporation solution growth technique at room temperature using methanol as the solvent. The 1H and 13C Nuclear magnetic resonance spectra were recorded to establish the molecular structure of the title salt. The crystal structure of the title crystal has been determined by single crystal X-ray diffraction analysis and it belongs to monoclinic crystal system with non-centrosymmetric space group P21. Fourier transform infrared spectral study has been carried out to confirm the presence of various functional groups. The optical transmittance spectrum was recorded in the range 200-2500 nm, to find the optical transmittance window and lower cut off wavelength. The thermo gravimetric and differential thermal analyses were carried out to establish the thermal stability of the title crystal. The second harmonic generation in the title crystal was confirmed by the modified Kurtz-Perry powder test employing the Nd: YAG laser as the source for infrared radiation.

  1. Crystal growth and scintillation characteristics of the Nd.sup.3+./sup. doped LaF.sub.3./sub. single crystal

    Czech Academy of Sciences Publication Activity Database

    Fukuda, K.; Kawaguchi, N.; Ishizu, S.; Yanagida, T.; Suyama, T.; Nikl, Martin; Yoshikawa, A.

    2010-01-01

    Roč. 32, č. 9 (2010), s. 1142-1145 ISSN 0925- 3467 Grant - others:AV(CZ) M100100910 Institutional research plan: CEZ:AV0Z10100521 Keywords : fluoride * single crystal * crystal growth from the melt * scintillator Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.679, year: 2010

  2. Crystal growth and scintillation characteristics of the Nd.sup.3+./sup. doped LiLuF.sub.4./sub. single crystals

    Czech Academy of Sciences Publication Activity Database

    Fukuda, K.; Kawaguchi, N.; Ishizu, S.; Nagami, T.; Suyama, T.; Yanagida, T.; Yokota, Y.; Nikl, Martin; Yoshikawa, A.

    2011-01-01

    Roč. 33, č. 6 (2011), s. 924-927 ISSN 0925- 3467 Grant - others:AV ČR(CZ) M100100910 Institutional research plan: CEZ:AV0Z10100521 Keywords : fluoride * single crystal * VUV Nd 3 + 5d–4f * crystal growth from the melt Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.023, year: 2011

  3. Growth of Bulk Wide Bandgap Semiconductor Crystals and Their Potential Applications

    Science.gov (United States)

    Chen, Kuo-Tong; Shi, Detang; Morgan, S. H.; Collins, W. Eugene; Burger, Arnold

    1997-01-01

    Developments in bulk crystal growth research for electro-optical devices in the Center for Photonic Materials and Devices since its establishment have been reviewed. Purification processes and single crystal growth systems employing physical vapor transport and Bridgman methods were assembled and used to produce high purity and superior quality wide bandgap materials such as heavy metal halides and II-VI compound semiconductors. Comprehensive material characterization techniques have been employed to reveal the optical, electrical and thermodynamic properties of crystals, and the results were used to establish improved material processing procedures. Postgrowth treatments such as passivation, oxidation, chemical etching and metal contacting during the X-ray and gamma-ray device fabrication process have also been investigated and low noise threshold with improved energy resolution has been achieved.

  4. Growth and PhysioChemical Properties of Second-Order Nonlinear Optical L-Threonine Single Crystals

    Directory of Open Access Journals (Sweden)

    G. Ramesh Kumar

    2009-01-01

    Full Text Available The present aim of the paper is to grow and to study the various properties of L-threonine amino acid single crystal in various aspects. Crystal growth of L-threonine single crystals has been carried out with the help of crystallization kinetics. pH and deuteration effects on the properties of the grown crystals have been studied and the results presented in a lucid manner. The various second-order NLO parameters were evaluated using anharmonic oscillator model. Particle and ion irradiation effects on structural, optical, and surface properties of the crystals have also been studied in detail.

  5. Bridgman growth and defects of Nd : Sr3Ga2Ge4O14 laser crystals

    Indian Academy of Sciences (India)

    Unknown

    . ... Nd3+ : SGG crystal; Bridgman method; EPMA; inclusion; dislocation. ... A pair of Pt–. Pt/Rh thermocouples was installed in the tube to measure the temperature of the melt near the top of the seed. The. Bridgman growth was carried out in a ...

  6. Large potassium dihydrogen phosphate crystal growth using a three-vessel system for fusion lasers

    International Nuclear Information System (INIS)

    Sasaki, T.; Yokotani, A.; Yamanaka, T.; Nakai, S.; Yamanaka, C.

    1989-01-01

    Large scale laser fusion experiments are being performed in the Institute of Laser Engineering, Osaka University, using the glass laser system Gekko-XII. For this laser, very large nonlinear crystals of potassium dihydrogen phosphate (KDP) with a cross section over 40 X 40 cm is needed as a frequency converter to obtain a short wavelength laser. Generally the temperature falling method (TFM) is used to grow such a huge crystal, but the volume of the growing vessel becomes tremendously large. The three-vessel system (TVS), which is a constant temperature and concentration method, allows better control of supersaturation than does the TFM, and the volume of the main growth vessel can be smaller than that in the case of the TFM. The authors have constructed a TVS. The KDP crystal grew in the growth tank that was kept at a constant temperature of 20 +- 0.01 0 C. The authors show the growth history of the KDP crystal of a 40- X 40-cm cross section. This system is now being operated to obtain the KDP of 100-cm height, and a theoretical estimate of the growth rate is under consideration. These results are presented

  7. Laminar and turbulent melt flow in computational modeling of crystal growth

    Czech Academy of Sciences Publication Activity Database

    Přikryl, Petr; Jelínek, Pavel; Černý, R.

    2002-01-01

    Roč. 3, - (2002), s. 201-208 ISSN 1108-7609 R&D Projects: GA ČR GA106/01/0648; GA ČR GA201/01/1200 Institutional research plan: CEZ:AV0Z1019905; CEZ:AV0Z1019905 Keywords : crystal growth * computational model * turbulent melt flow Subject RIV: BK - Fluid Dynamics

  8. Identification of a macromolecular crystal growth inhibitor in human urine as osteopontin

    DEFF Research Database (Denmark)

    Sørensen, Steen; Justesen, S J; Johnsen, A H

    1995-01-01

    Macromolecules occurring in human urine inhibit the growth and/or aggregation of calcium oxalate crystals and may prevent the formation of kidney stones. Attention has focused particularly on proteins, as these seem to be most responsible for the inhibitory activity; three proteins, nephrocalcin...

  9. Growth of Nd doped LiNbO3 crystals using Bridgman method and its ...

    Indian Academy of Sciences (India)

    Administrator

    Laboratory of Photo-Electronic Materials, Ningbo University, Ningbo 315211, PR China. ††. College of Chemical and Materials Engineering, Zhejiang University of Technology,. Hangzhou 310014, PR China. MS received 23 July 2008; revised 10 October 2008. Abstract. The growth of Nd. 3+ doped lithium niobate crystals ...

  10. Growth and study of barium oxalate single crystals in agar gel

    Indian Academy of Sciences (India)

    Unknown

    In the present work, agar–agar gel (Brezina and Harvan- kova 1991; Agrawal et al 1999) was preferentially used for the growth of crystals by single and double diffusion tech- niques. A test tube having 25 cm in length and 2⋅5 cm in dia- meter was employed. In single diffusion, hot aqueous agar gel and oxalic acid solution ...

  11. Melt growth and properties of bulk BaSnO3 single crystals

    Science.gov (United States)

    Galazka, Z.; Uecker, R.; Irmscher, K.; Klimm, D.; Bertram, R.; Kwasniewski, A.; Naumann, M.; Schewski, R.; Pietsch, M.; Juda, U.; Fiedler, A.; Albrecht, M.; Ganschow, S.; Markurt, T.; Guguschev, C.; Bickermann, M.

    2017-02-01

    We present the first-time growth of bulk BaSnO3 single crystals from the melt by direct solidification, their basic electrical and optical properties as well as their structural quality. Our measurement of the melting point (MP) of BaSnO3 amounts to 1855 °C  ±  25 K. At this temperature an intensive decomposition and non-stoichiometric evaporation takes place as the partial pressure of SnO(g) is about 90 times higher than that of BaO(g). X ray powder diffraction identified only the BaSnO3 perovskite phase, while narrow rocking curves having a full width at half maximum of 26 arcsec and etch pit densities below 106 cm-2 confirm a high degree of structural perfection of the single crystals. In this respect they surpass the structural properties of those single crystals that were reported in the literature. The electrical conductivity of nominally undoped crystals depends on the growth conditions and ranges from insulating to medium n-type conductivity. After post-growth annealing in an oxidizing atmosphere undoped crystals are generally insulating. Doping the crystals with lanthanum during growth results in a high n-type conductivity. For a La doping concentration of 0.123 wt.% we measured an electron concentration of 3.3  ×  1019 cm-3 and an electron mobility of 219 cm2 V-1 s-1. Based on optical absorption measurements we determined an energy of 3.17  ±  0.04 eV at 5 K and of 2.99  ±  0.04 eV at 297 K for the indirect band gap of BaSnO3.

  12. Crystal growth and optical properties of Gd admixed Ce-doped Lu.sub.2./sub.Si.sub.2./sub.O.sub.7./sub. single crystals

    Czech Academy of Sciences Publication Activity Database

    Horiai, T.; Kurosawa, S.; Murakami, R.; Yamaji, A.; Shoji, Y.; Ohashi, Y.; Pejchal, Jan; Kamada, K.; Yokota, Y.; Yoshikawa, A.

    2017-01-01

    Roč. 468, Jun (2017), s. 391-394 ISSN 0022-0248 Grant - others:AV ČR(CZ) JSPS-17-18 Program:Bilaterální spolupráce Institutional support: RVO:68378271 Keywords : growth from melt * seed crystals * single crystal growth * oxides * scintillator materials Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.751, year: 2016

  13. Modifications of micro-pulling-down method for the growth of selected Li-containing crystals for neutron scintillator and VUV scintillation crystals

    Science.gov (United States)

    Pejchal, J.; Fujimoto, Y.; Chani, V.; Yanagida, T.; Yokota, Y.; Yoshikawa, A.; Nikl, M.; Beitlerova, A.

    2012-12-01

    To develop new and efficient neutron scintillator, Ti-doped LiAlO2 single crystal was grown by micro-pulling-down method. The X-ray excited radioluminescence spectra and neutron light yield were measured. Positive effect of Mg codoping on the overall scintillation efficiency was found. The BaLu2F8 single crystal was grown by micro-pulling-down method using low temperature gradient at growth interface and applying quenching immediately after growth process.

  14. Cupola Furnace Computer Process Model

    Energy Technology Data Exchange (ETDEWEB)

    Seymour Katz

    2004-12-31

    The cupola furnace generates more than 50% of the liquid iron used to produce the 9+ million tons of castings annually. The cupola converts iron and steel into cast iron. The main advantages of the cupola furnace are lower energy costs than those of competing furnaces (electric) and the ability to melt less expensive metallic scrap than the competing furnaces. However the chemical and physical processes that take place in the cupola furnace are highly complex making it difficult to operate the furnace in optimal fashion. The results are low energy efficiency and poor recovery of important and expensive alloy elements due to oxidation. Between 1990 and 2004 under the auspices of the Department of Energy, the American Foundry Society and General Motors Corp. a computer simulation of the cupola furnace was developed that accurately describes the complex behavior of the furnace. When provided with the furnace input conditions the model provides accurate values of the output conditions in a matter of seconds. It also provides key diagnostics. Using clues from the diagnostics a trained specialist can infer changes in the operation that will move the system toward higher efficiency. Repeating the process in an iterative fashion leads to near optimum operating conditions with just a few iterations. More advanced uses of the program have been examined. The program is currently being combined with an ''Expert System'' to permit optimization in real time. The program has been combined with ''neural network'' programs to affect very easy scanning of a wide range of furnace operation. Rudimentary efforts were successfully made to operate the furnace using a computer. References to these more advanced systems will be found in the ''Cupola Handbook''. Chapter 27, American Foundry Society, Des Plaines, IL (1999).

  15. Potassium terbium fluoride crystal growth development for faraday rotator discs fabrication, 6 July 1978--6 February 1979

    Energy Technology Data Exchange (ETDEWEB)

    1979-05-17

    Crystal growth experiments were performed and growth of KTb/sub 3/F/sub 10/ crystals were accomplished. The crystal growth experiments consisted of hot zone modification and development of growth parameters. Several boules of KTb/sub 3/F/sub 10/ 30 to 40mm in diameter and one boule 50mm in diameter were grown at rates varying from .5mm/hr to 3.0mm/hr. The crystals evaluated display excellent optical quality. The optical path distortion was less than 0.5 fringe/cm at 633nm as viewed in Twyman--Green interferometry. Growth of large crystals has been limited by mechanical cleavage.

  16. Crystal growth, morphology, thermal and spectral studies of an organosulfur nonlinear optical bis(guanidinium) 5-sulfosalicylate (BG5SS) single crystals

    Science.gov (United States)

    Dhavamurthy, M.; Peramaiyan, G.; Babu, K. Syed Suresh; Mohan, R.

    2015-04-01

    Organosulfur nonlinear optical single crystals of orthorhombic bis(guanidinium) 5-sulfosalicylate (2CH6N3 +·C7H4O6S2-·H2O) with dimension 14 mm × 4 mm × 5 mm have been grown from methanol and water solvents in 1:1 ratio by the slow evaporation growth technique. The crystal structure and morphology of the crystals have been studied by single-crystal X-ray diffraction. FTIR spectroscopic studies were carried out to identify the functional groups and vibrational modes present in the grown crystals. The UV-Vis spectrum was studied to analyze the linear optical properties of the grown crystals. The thermal gravimetric analysis was conducted on the grown crystals, and the result revealed that the grown crystal is thermally stable up to 65 °C. The dielectric tensor components ɛ 11, ɛ 22 and ɛ 33 of BG5SS crystal were evaluated as a function of frequency at 40 °C. The surface laser damage threshold for the grown crystal was measured using Nd:YAG laser. Further, Vickers micro-hardness study was carried out to analyze the mechanical strength of the grown crystals for various loads.

  17. Recharging the Silicon Crucible in a Hot Furnace

    Science.gov (United States)

    Lane, R. L.

    1982-01-01

    "Melt recharger" adds raw silicon to crucible in crystal-growing furnace without disturbing inert-gas atmosphere or significantly lowering temperature of melt. Crucible-refill hopper is lowered into hot zone of crystal-pulling chamber through an isolation valve. Cable that supports hopper is fastened to cone-shaped stopper in bottom of hopper. Stopper moves out of opening in hopper, allowing part of polysilicon charge to drop into crucible.

  18. Growth kinetics of NaCl crystals in a drying drop of gelatin: transition from faceted to dendritic growth

    Science.gov (United States)

    Dutta Choudhury, Moutushi; Dutta, Tapati; Tarafdar, Sujata

    We report a study on the kinetics of drying of a droplet of aqueous gelatin containing sodium chloride. The process of drying recorded on video, clearly shows different regimes of growth leading to a variety of crystalline patterns. Large faceted crystals of $\\sim$mm size form in the early stages of evaporation, followed by highly branched multi-fractal patterns with micron sized features. We simulate the growth using a simple algorithm incorporating aggregation and evaporation, which reproduces the cross-over between the two growth regimes. As evaporation proceeds, voids form in the gel film. The time development of the fluid-void system can be characterized by an Euler number. A minimum in the Euler number marks the transition between the two regimes of growth.

  19. Crystal growth mechanisms and morphological control of the prototypical metal-organic framework MOF-5 revealed by atomic force microscopy.

    Science.gov (United States)

    Cubillas, Pablo; Anderson, Michael W; Attfield, Martin P

    2012-11-26

    Crystal growth of the metal-organic framework MOF-5 was studied by atomic force microscopy (AFM) for the first time. Growth under low supersaturation conditions was found to occur by a two-dimensional or spiral crystal growth mechanism. Observation of developing nuclei during the former reveals growth occurs through a process of nucleation and spreading of metastable and stable sub-layers revealing that MOFs may be considered as dense phase structures in terms of crystal growth, even though they contain sub-layers consisting of ordered framework and disordered non-framework components. These results also support the notion this may be a general mechanism of surface crystal growth at low supersaturation applicable to crystalline nanoporous materials. The crystal growth mechanism at the atomistic level was also seen to vary as a function of the growth solution Zn/H(2)bdc ratio producing square terraces with steps parallel to the direction or rhombus-shaped terraces with steps parallel to the direction when the Zn/H(2)bdc ratio was >1 or about 1, respectively. The change in relative growth rates can be explained in terms of changes in the solution species concentrations and their influence on growth at different terrace growth sites. These results were successfully applied to the growth of as-synthesized cube-shaped crystals to increase expression of the {111} faces and to grow octahedral crystals of suitable quality to image using AFM. This modulator-free route to control the crystal morphology of MOF-5 crystals should be applicable to a wide variety of MOFs to achieve the desired morphological control for performance enhancement in applications. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Chemically Engineered Substrates for Patternable Growth of Two-Dimensional Chalcogenide Crystals.

    Science.gov (United States)

    Wang, Mingzhan; Wu, Jinxiong; Lin, Li; Liu, Yujing; Deng, Bing; Guo, Yunfan; Lin, Yuanwei; Xie, Tian; Dang, Wenhui; Zhou, Yubing; Peng, Hailin

    2016-11-22

    The key challenge of direct integration of two-dimensional (2D) chalcogenide crystals into functional modules is precise control of the nucleation sites of the building blocks. Herein, we exploit the chemical activities and surface engineering of the substrates to manipulate the nucleation energy barrier of 2D crystals and thereby realize the patternable growth of 2D crystals. The selective-region chemical modifications of the substrates are achieved via microcontact printing combined with the elegant self-assembly of octadecyltrichlorosilane molecules on the substrates. The patternable growth method is versatile and can be used as a general strategy for growing a broad class of high-quality 2D chalcogenide crystals with tailorable configurations on a variety of chemically engineered substrates. Moreover, we demonstrate flexible transparent electrodes based on large-scale patterned nanogrids of topological insulator Bi 2 Se 3 , which possess tailored trade-off between electric conductivity and optical transmittance across the visible to near-infrared regime. We hope this method may open an avenue to the efficient integration and batch production of 2D chalcogenide crystals and could inspire ongoing efforts of the fabrication of van der Waals heterostructures.

  1. Epitaxial Growth of Ternary Topological Insulator Bi2 Te2 Se 2D Crystals on Mica.

    Science.gov (United States)

    Liu, Yujing; Tang, Min; Meng, Mengmeng; Wang, Mingzhan; Wu, Jinxiong; Yin, Jianbo; Zhou, Yubing; Guo, Yunfan; Tan, Congwei; Dang, Wenhui; Huang, Shaoyun; Xu, H Q; Wang, Yong; Peng, Hailin

    2017-05-01

    Nanostructures of ternary topological insulator (TI) Bi 2 Te 2 Se are, in principle, advantageous to the manifestation of topologically nontrivial surface states, due to significantly enhanced surface-to-volume ratio compared with its bulk crystals counterparts. Herein, the synthesis of 2D Bi 2 Te 2 Se crystals on mica via the van der Waals epitaxy method is explored and systematically the growth behaviors during the synthesis process are investigated. Accordingly, 2D Bi 2 Te 2 Se crystals with domain size up to 50 µm large and thickness down to 2 nm are obtained. A pronounced weak antilocalization effect is clearly observed in the 2D Bi 2 Te 2 Se crystals at 2 K. The method for epitaxial growth of 2D ternary Bi 2 Te 2 Se crystals may inspire materials engineering toward enhanced manifestation of the subtle surface states of TIs and thereby facilitate their potential applications in next-generation spintronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. CORELESS INDUCTION FURNACE. CONSTRUCTIVE DIFFERENCES, OPERATION

    Directory of Open Access Journals (Sweden)

    A. N. Saharevich

    2012-01-01

    Full Text Available The main tendencies of development of induction crucible furnaces are considered. constructive differences of crucible furnaces in comparison with fuel furnaces are given. The area of their application is specified.

  3. Growth of ZnO crystals by vapour transport: Some ways to act on physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Tena-Zaera, R.; Martinez-Tomas, C.; Munoz-Sanjose, V. [Dept. Fisica Aplicada i Electromagnetisme, Universitat de Valencia, C/ Dr. Moliner 50, 46100 Burjassot (Spain); Gomez-Garcia, C.J. [Instituto de Ciencia Molecular, Universitat de Valencia, C/ Dr. Moliner 50, 46100 Burjassot (Spain)

    2006-08-15

    Nowadays, the growth of ZnO by vapor transport in silica ampoules is generally made in presence of graphite. As it has been already shown, this means that the growth process is carried out in presence of a Zn excess. In order to control that and act, as a consequence, on the physical properties of crystals we have performed a systematic study of the growth process in a wide range of Zn excess compositions using well defined experimental conditions. As a preliminary characterization, optical absorption and electrical properties have been analyzed at room temperature. The results show how some physical properties of as-grown ZnO crystals can be changed in a controlled way by an adequate combination of different growth conditions such as graphite covering of inner ampoule walls, thermal difference between source material and crystallization zone and additional gas (composition and pressure). In this frame some post-growth annealing processes can be avoided reducing the time and cost of processes. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Ultrafast growth of single-crystal graphene assisted by a continuous oxygen supply

    Science.gov (United States)

    Xu, Xiaozhi; Zhang, Zhihong; Qiu, Lu; Zhuang, Jianing; Zhang, Liang; Wang, Huan; Liao, Chongnan; Song, Huading; Qiao, Ruixi; Gao, Peng; Hu, Zonghai; Liao, Lei; Liao, Zhimin; Yu, Dapeng; Wang, Enge; Ding, Feng; Peng, Hailin; Liu, Kaihui

    2016-11-01

    Graphene has a range of unique physical properties and could be of use in the development of a variety of electronic, photonic and photovoltaic devices. For most applications, large-area high-quality graphene films are required and chemical vapour deposition (CVD) synthesis of graphene on copper surfaces has been of particular interest due to its simplicity and cost effectiveness. However, the rates of growth for graphene by CVD on copper are less than 0.4 μm s-1, and therefore the synthesis of large, single-crystal graphene domains takes at least a few hours. Here, we show that single-crystal graphene can be grown on copper foils with a growth rate of 60 μm s-1. Our high growth rate is achieved by placing the copper foil above an oxide substrate with a gap of ∼15 μm between them. The oxide substrate provides a continuous supply of oxygen to the surface of the copper catalyst during the CVD growth, which significantly lowers the energy barrier to the decomposition of the carbon feedstock and increases the growth rate. With this approach, we are able to grow single-crystal graphene domains with a lateral size of 0.3 mm in just 5 s.

  5. Silicon impurity as a possible growth-regime indicator for LiNbO3 crystals

    Energy Technology Data Exchange (ETDEWEB)

    Erdei, S.; Szaller, Z.; Raksanyi, K.; Matok, G.

    1985-08-01

    The influence of Si concentration and temperature regimes on the visually observable properties of LiNbO3 single crystals grown by Czochralski method was studied. Si concentration measurements were carried out and minima in the radial and axial distribution curves have been established. An upper estimate is given for the equilibrium distribution coefficient of Si in LiNbO3. A direct correlation has been found between the degree of opacity and the Si concentration. The variation of the Grashof number during growth and a correlated modification of the structure of the concentration layer width, implying a position dependent fulfilment of the Hurle-Bardsley criterium for constitutional super cooling, accounts reasonably well with the visually observable properties of the opaque regions appearing in the course of crystal growth. The use of Si as an overall indicator for the characterization of growth regimes is discussed.

  6. Crystal Growth and Glass-Like Thermal Conductivity of Ca3RE2(BO34 (RE = Y, Gd, Nd Single Crystals

    Directory of Open Access Journals (Sweden)

    L. V. Gudzenko

    2017-03-01

    Full Text Available Crystal growth and thermal properties of binary borates, Ca3RE2(BO34 (RE = Y, Gd, Nd, are considered promising crystals for laser applications. These single crystals were grown by the Czochralski method. The crystal and defect structure were characterized. Volumetric chemical methods without prior separation of the components were developed and applied for the determination of the dependence of chemical compositions of the crystals on the growth conditions. The thermal conductivity was investigated in the 50–300 K range. The character of the temperature dependence of thermal conductivity was found to be similar to that of glass. The possible reasons of the observed features of the thermal conductivity were analyzed.

  7. Growth of tourmaline single crystals containing transition metal elements in hydrothermal solutions

    Science.gov (United States)

    Setkova, Tatiana; Shapovalov, Yury; Balitsky, Vladimir

    2011-03-01

    Interest in the growth of tourmaline single crystals is based on the promising piezoelectric and pyroelectric properties of this material compared to quartz crystals currently in use. Moreover, synthetic tourmaline can be used as a substitute for the natural stone in the jewelry industry similar to other synthetic analogues of gemstones. Single crystals of colored Co-, Ni-, Fe-, (Ni,Cr)-, (Ni,Fe)-, and (Co,Ni,Cr)-containing tourmalines with concentration of transition metal elements up to 16 wt% on a seed have been grown from complex boron-containing hydrothermal solutions at a range of temperatures 400-750 °C and pressures 100 MPa. Experiments were conducted under conditions of a thermal gradient in titanium and chromium-nickel autoclaves. Tourmaline growth on a seed crystal occurs only if separate tourmaline-forming components (monocrystalline corundum and quartz bars) are used as charge. All tourmalines specified above grow in analogous (+) direction of the optical axis with a speed of 0.05 mm/day by faces of the trigonal pyramid, except tourmalines containing chromium. They grow in analogous (+0001) direction with a speed 0.05 mm/day, and in antilogous (-0001) direction with a speed of 0.01 mm/day by faces of the trigonal pyramid and in prism direction with a speed of 0.001 mm/day. Along with the large single crystals, a great amount of finest (30-150 μm in size) tourmaline crystals was formed during the runs by spontaneous nucleation both on the surface of the seed crystals and in the charge.

  8. Large-size TlBr single crystal growth and defect study

    Science.gov (United States)

    Zhang, Mingzhi; Zheng, Zhiping; Chen, Zheng; Zhang, Sen; Luo, Wei; Fu, Qiuyun

    2018-04-01

    Thallium bromide (TlBr) is an attractive semiconductor material for fabrication of radiation detectors due to its high photon stopping power originating from its high atomic number, wide band gap and high resistivity. In this paper the vertical Bridgman method was used for crystal growth and TlBr single crystals with diameter of 15 mm were grown. X-ray diffraction (XRD) was used to identify phase and orientation. Electron backscatter diffraction (EBSD) was used to investigate crystal microstructure and crystallographic orientation. The optical and electric performance of the crystal was characterized by infrared (IR) transmittance spectra and I-V measurement. The types of point defects in the crystals were investigated by thermally stimulated current (TSC) spectra and positron annihilation spectroscopy (PAS). Four types of defects, with ionization energy of each defect fitting as follows: 0.1308, 0.1540, 0.3822 and 0.538 eV, were confirmed from the TSC result. The PAS result showed that there were Tl vacancies in the crystal.

  9. Numerical model of protein crystal growth in a diffusive field such as the microgravity environment

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiroaki, E-mail: tanakah@confsci.co.jp [Confocal Science Inc., Hayakawa 2nd Building 7F, 2-12-2 Iwamoto-cho, Chiyoda-ku, Tokyo 101-0032 (Japan); Sasaki, Susumu [Neo Force, 5-9-14-403 Tsurumaki, Setagaya-ku, Tokyo 154-0016 (Japan); Takahashi, Sachiko [Confocal Science Inc., Hayakawa 2nd Building 7F, 2-12-2 Iwamoto-cho, Chiyoda-ku, Tokyo 101-0032 (Japan); Inaka, Koji [Maruwa Foods and Biosciences Inc., 170-1 Tsutsui-cho, Yamatokoriyama, Nara 639-1123 (Japan); Wada, Yoshio; Yamada, Mitsugu; Ohta, Kazunori; Miyoshi, Hiroshi; Kobayashi, Tomoyuki; Kamigaichi, Shigeki [Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-8505 (Japan)

    2013-11-01

    Numerical analysis of the concentration depletion zones in a transient state suggested that, in microgravity, protein crystals grow in a lower supersaturation and the impurity ratio decreases in the centre of the crystal. It is said that the microgravity environment positively affects the quality of protein crystal growth. The formation of a protein depletion zone and an impurity depletion zone due to the suppression of convection flow were thought to be the major reasons. In microgravity, the incorporation of molecules into a crystal largely depends on diffusive transport, so the incorporated molecules will be allocated in an orderly manner and the impurity uptake will be suppressed, resulting in highly ordered crystals. Previously, these effects were numerically studied in a steady state using a simplified model and it was determined that the combination of the diffusion coefficient of the protein molecule (D) and the kinetic constant for the protein molecule (β) could be used as an index of the extent of these depletion zones. In this report, numerical analysis of these depletion zones around a growing crystal in a non-steady (i.e. transient) state is introduced, suggesting that this model may be used for the quantitative analysis of these depletion zones in the microgravity environment.

  10. Polyol synthesis of silver nanoplates: The crystal growth mechanism based on a rivalrous adsorption

    International Nuclear Information System (INIS)

    Luo Xiaolin; Li Zongxiao; Yuan Chunlan; Chen Yashao

    2011-01-01

    Highlights: → Silver nanoplates have been successfully synthesized by polyol reduction in the presence of poly (vinylpyrrolidone) (PVP) and HNO 3 . → Due to the discovery of CN - ions in the solution, a mechanism for the anisotropic growth of silver nanoplates is systematically discussed. → TG, FT-IR and SERS were used to provide some direct evidences of rivalrous adsorption between PVP and CN - ions on the surface of the silver crystals. - Abstract: A polyol reducing approach has been applied to synthesize silver nanoplates with an average thickness of 50 nm and edge length of 3 μm in the presence of poly (vinylpyrrolidone) (PVP) and HNO 3 . X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscropy (TEM), and electron diffraction are used to characterize these silver nanoplates. Findings indicate that the nanoplates are single crystals and with their basal plane as (1 1 1) lattice plane. On the basis of the results from thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy, a crystal growth mechanism based on the rivalrous adsorption between PVP and CN - ions on the surface of silver nanoplates is supposed to explain the crystal anisotropic growth.

  11. Probing and characterizing the growth of a crystal of ultracold bosons and light

    Science.gov (United States)

    Ostermann, S.; Piazza, F.; Ritsch, H.

    2017-12-01

    The non-linear coupled particle light dynamics of an ultracold gas in the field of two independent counter-propagating laser beams can lead to the dynamical formation of a self-ordered lattice structure as presented in (2016) Phys. Rev. X 6 021026. Here we present new numerical studies on experimentally observable signatures to monitor the growth and properties of such a crystal in real time. While, at least theoretically, optimal non-destructive observation of the growth dynamics and the hallmarks of the crystalline phase can be performed by analyzing scattered light, monitoring the evolution of the particle’s momentum distribution via time-of-flight probing is an experimentally more accessible choice. In this work we show that both approaches allow us to unambiguously distinguish the crystal from independent collective scattering as it occurs in matter wave super-radiance. As a clear crystallization signature, we identify spatial locking between the two emerging standing laser waves, together creating the crystal potential. For sufficiently large systems, the system allows reversible adiabatic ramping into the crystalline phase as an alternative to a quench across the phase transition and growth from fluctuations.

  12. Growth and characterization of CdTe single crystals for radiation detectors

    CERN Document Server

    Funaki, M; Satoh, K; Ohno, R

    1999-01-01

    To improve the productivity of CdTe radiation detectors, the crystal growth by traveling heater method (THM) as well as the quality of the fabricated detectors were investigated. In the THM growth, optimization of the solvent volume was found to be essential because it affects the shape of the growth interface. The use of the slightly tilted seed from B was also effective to limit the generation of twins having different directions. Single-crystal (1 1 1) wafers, larger than 30x30 mm sup 2 were successfully obtained from a grown crystal of 50 mm diameter. Pt/CdTe/Pt detectors of dimensions 4x4x2 mm sup 3 , fabricated from the whole crystal ingot, showed an energy resolution (FWHM of 122 keV peak from a sup 5 sup 7 Co source) between 6% and 8%. Similarly, Pt/CdTe/In detectors of dimensions 2x2x0.5 mm sup 3 showed a resolution better than 3%. These characteristics encourage the practical applications of various types of CdTe detectors.

  13. Assess progress being made for the KTeV electromagnetic calorimeter crystal order in France

    Science.gov (United States)

    Childress, S. R.

    1993-08-01

    This report contains a record of our activities at the Quartz & Silice facility during this visit. Significant progress was achieved in illustrating the importance and practical application of particular measurements in characterizing crystal quality, and in understanding problems with crystal polishing techniques currently being used. Detailed discussions with Quartz & Silice personnel on these issues were held, as were discussions on current production and furnace growth cycle options which may significantly increase ingot production rates.

  14. Directory of crystal growth and solid state materials production and research

    International Nuclear Information System (INIS)

    Connolly, T.F.; Battle, G.C.; Keesee, A.M.

    1979-03-01

    This directory lists only those who returned questionnaires distributed by the Research Materials Information Center during 1978. The directory includes, in addition to crystal growers, those preparing starting materials for crystal growth and ultrapure noncrystalline research specimens. It also includes responses from those characterizing, or otherwise studying, the properties of materials provided by others. The international coverage of the directory is limited to the United States, Argentina, Australia, Bulgaria, Canada, Czechoslovakia, Egypt, Finland, East Germany, Hungary, India, Israel, Japan, Mexico, Poland, Romania, South Africa, Taiwan, Yugoslavia, and Zaire

  15. Directory of crystal growth and solid state materials production and research

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, T.F.; Battle, G.C.; Keesee, A.M. (comps.)

    1979-03-01

    This directory lists only those who returned questionnaires distributed by the Research Materials Information Center during 1978. The directory includes, in addition to crystal growers, those preparing starting materials for crystal growth and ultrapure noncrystalline research specimens. It also includes responses from those characterizing, or otherwise studying, the properties of materials provided by others. The international coverage of the directory is limited to the United States, Argentina, Australia, Bulgaria, Canada, Czechoslovakia, Egypt, Finland, East Germany, Hungary, India, Israel, Japan, Mexico, Poland, Romania, South Africa, Taiwan, Yugoslavia, and Zaire.

  16. Influence of vacuum degree on growth of Bi2Te3 single crystal

    Science.gov (United States)

    Tang, Yan-Kun; Zhao, Wen-Juan; Zhu, Hua-Qiang; Huang, Yong-Chao; Cao, Wei-Wei; Yang, Qian; Yao, Xiao-Yan; Zhai, Ya; Dong, Shuai

    2015-07-01

    Bi2Te3 single crystals were prepared by the solid-state reaction method. The effect of the vacuum on the growth of Bi2Te3 single crystals was studied with varying the oxygen content by controlling the air pressure in the silica tube. High quality Bi2Te3 single crystals have been obtained and there is no influence on the growth by an extremely small amount of oxygen in a high vacuum at 1.0 × 10-3 Pa. As the air pressure is increased at 1.0 × 10-2 Pa, oxygen only mainly impacts on the growth of the surface for the prepared samples. Micron-sized rod-like structure and flower-like clusters are observed on the surface. For the samples prepared at 1.0 × 10-1 Pa, x-ray diffraction data show that the yellow part on the surface is Bi2TeO5, while the Bi2Te3 single crystal is still the major phase as the inside part. More interestingly, various crystal morphologies are observed by scanning electron microscope for Bi2Te3 near the boundary between Bi2Te3 and Bi2TeO5. Possible growth mechanisms for Bi2Te3 with different morphologies are discussed in detail. Project supported by the National Natural Science Foundation of China (Grant Nos. 10904013 and 11274060), the Natural Science Foundation of Jiangsu Province, China (Grant Nos. BK2009260 and BK20141329), and the Scientific Research Staring Foundation for the Returned Overseas Chinese Scholars,Ministry of Education of China.

  17. Synthesis and single crystal growth of perovskite semiconductor CsPbBr3

    Science.gov (United States)

    Zhang, Mingzhi; Zheng, Zhiping; Fu, Qiuyun; Chen, Zheng; He, Jianle; Zhang, Sen; Chen, Cheng; Luo, Wei

    2018-02-01

    As a typical representative of all-inorganic lead halide perovskites, cesium lead bromine (CsPbBr3) has attracted significant attention in recent years. The direct band gap semiconductor CsPbBr3 has a wide band gap of 2.25 eV and high average atomic number (Cs: 55, Pb: 82 and Br: 35), which meet most of the requirements for detection of X- and γ-ray radiation, such as high attenuation, high resistivity, and significant photoconductivity response. However, the growth of large volume CsPbBr3 single crystals remains a challenge. In this paper, the synthesis of CsPbBr3 polycrystalline powders by a chemical co-precipitation method was investigated and the optimum synthesis conditions were obtained. A large CsPbBr3 single crystal of 8 mm diameter and 60 mm length was obtained by a creative electronic dynamic gradient (EDG) method. X-ray diffraction (XRD) patterns and X-ray rocking curve showed that the CsPbBr3 crystal preferentially oriented in the (1 1 0) direction and had a low dislocation density and small residual stress in the crystal. The IR and UV-Vis transmittance and temperature-dependent photoluminescence (PL) spectra showed the crystal had a good basic optical performance. The almost linear current-voltage (I-V) curves implied good ohmic contact between the electrodes and crystal surfaces. The resistivity of the crystal was calculated 109-1010 Ω cm. The above results showed that the quality of the obtained crystal had met the demand of optoelectronic applications.

  18. On the origin of surface imposed anisotropic growth of salicylic and acetylsalicylic acids crystals during droplet evaporation.

    Science.gov (United States)

    Przybyłek, Maciej; Cysewski, Piotr; Pawelec, Maciej; Ziółkowska, Dorota; Kobierski, Mirosław

    2015-03-01

    In this paper droplet evaporative crystallization of salicylic acid (SA) and acetylsalicylic acid (ASA) crystals on different surfaces, such as glass, polyvinyl alcohol (PVA), and paraffin was studied. The obtained crystals were analyzed using powder X-ray diffraction (PXRD) technique. In order to better understand the effect of the surface on evaporative crystallization, crystals deposited on glass were scraped off. Moreover, evaporative crystallization of a large volume of solution was performed. As we found, paraffin which is non-polar surface promotes formation of crystals morphologically similar to those obtained via bulk evaporative crystallization. On the other hand, when crystallization is carried out on the polar surfaces (glass and PVA), there is a significant orientation effect. This phenomenon is manifested by the reduction of the number of peaks in PXRD spectrum recorded for deposited on the surface crystals. Noteworthy, reduction of PXRD signals is not observed for powder samples obtained after scraping crystals off the glass. In order to explain the mechanism of carboxylic crystals growth on the polar surfaces, quantum-chemical computations were performed. It has been found that crystal faces of the strongest orientation effect can be characterized by the highest surface densities of intermolecular interactions energy (IIE). In case of SA and ASA crystals formed on the polar surfaces the most dominant faces are characterized by the highest adhesive and cohesive properties. This suggests that the selection rules of the orientation effect comes directly from surface IIE densities.

  19. Investigation on the influence of foreign metal ions in crystal growth and characterization of L-Alaninium Maleate (LAM) single crystals.

    Science.gov (United States)

    Ruby Nirmala, L; Thomas Joseph Prakash, J

    2013-11-01

    A Nonlinear Optical, good quality, single crystals of doped and undoped l-Alaninium Maleate (LAM) were grown by slow evaporation solution growth technique at room temperature. The lattice parameters were analyzed by single crystal X-ray diffraction technique. The identification of Cadmium ion in the doped crystals was done using the EDAX spectrum. The presence of functional group of the dopant with LAM molecule was studied using FTIR spectra. The results of UV-Vis study is used to compare the transparencies of the doped and undoped LAM crystals. The optical band gap energy of the grown crystal was also calculated. The relative second harmonic generation (SHG) efficiency measurement with KDP reference is used to find the incorporation of metal to l-Alaninium Maleate crystals and the parent material. Also the thermal stability of the grown crystals was studied by TGA/DTA spectrum. The mechanical stability of the grown crystals was confirmed through Vickers micro hardness study. By parallel plate capacitor technique, the dielectric response was studied over a wide range of frequencies at different temperatures. The various studies showed the incorporation of the impurity Cd(2+) into LAM crystals and the investigations indicated that the impurity played an important role in the changes of the spectral and structural properties of LAM crystals. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Dynamic light scattering study of inhibition of nucleation and growth of hydroxyapatite crystals by osteopontin.

    Directory of Open Access Journals (Sweden)

    John R de Bruyn

    Full Text Available We study the effect of isoforms of osteopontin (OPN on the nucleation and growth of crystals from a supersaturated solution of calcium and phosphate ions. Dynamic light scattering is used to monitor the size of the precipitating particles and to provide information about their concentration. At the ion concentrations studied, immediate precipitation was observed in control experiments with no osteopontin in the solution, and the size of the precipitating particles increased steadily with time. The precipitate was identified as hydroxyapatite by X-ray diffraction. Addition of native osteopontin (nOPN extracted from rat bone caused a delay in the onset of precipitation and reduced the number of particles that formed, but the few particles that did form grew to a larger size than in the absence of the protein. Recombinant osteopontin (rOPN, which lacks phosphorylation, caused no delay in initial calcium phosphate precipitation but severely slowed crystal growth, suggesting that rOPN inhibits growth but not nucleation. rOPN treated with protein kinase CK2 to phosphorylate the molecule (p-rOPN produced an effect similar to that of nOPN, but at higher protein concentrations and to a lesser extent. These results suggest that phosphorylations are critical to OPN's ability to inhibit nucleation, whereas the growth of the hydroxyapatite crystals is effectively controlled by the highly acidic OPN polypeptide. This work also demonstrates that dynamic light scattering can be a powerful tool for delineating the mechanism of protein modulation of mineral formation.

  1. Synthesis, growth, structural, optical, thermal, electrical and mechanical properties of hydrogen bonded organic salt crystal: Triethylammonium-3, 5-dinitrosalicylate

    Science.gov (United States)

    Rajkumar, Madhu; Chandramohan, Angannan

    2017-04-01

    Triethylammonium-3, 5-dinitrosalicylate, an organic salt was synthesized and single crystals grown by slow solvent evaporation solution growth technique using methanol as a solvent. The presence of various functional groups and mode of vibrations has been confirmed by FT-IR spectroscopic technique. The UV-vis-NIR Spectrum was recorded in the range 200-1200 nm to find optical transmittance window and lower cut off wavelength of the title crystal. The formation of the salt and the molecular structure was confirmed by NMR spectroscopic technique. Crystal system, crystalline nature, cell parameters and hydrogen bonding interactions of the grown crystal were determined by single crystal x-ray diffraction analysis. The thermal characteristics of grown crystal were analyzed by thermo gravimetric and differential thermal analyses. Dielectric studies were carried out to study the distribution of charges within the crystal. The mechanical properties of the title crystal were studied by Vicker's microhardness technique.

  2. Acousto-optical phonon excitation in cubic piezoelectric slabs and crystal growth orientation effects

    DEFF Research Database (Denmark)

    Willatzen, Morten; Duggen, Lars

    2017-01-01

    In this paper we investigate theoretically the influence of piezoelectric coupling on phonon dispersion relations. Specifically we solve dispersion relations for a fully coupled zinc-blende freestanding quantum well for different orientations of the crystal unit cell. It is shown that the phonon...... mode density in GaAs can change by a factor of approximately 2–3 at qx a = 1 for different crystal-growth directions relative to the slab thickness direction. In particular, it is found that optical and acoustic phonon modes are always piezoelectrically coupled, independent of the crystal...... that the piezoelectric effect leads to a drastically enhanced coupling of acoustic and optical phonon modes and increase in the local phonon density of states near the plasma frequency where the permittivity approaches zero....

  3. The growth, spectral and thermal properties of the coordination compound crystal-strontium malate

    International Nuclear Information System (INIS)

    Jini, T.; Saban, K.V.; Varghese, G.

    2006-01-01

    Growth of single crystals of the title compound Sr(C 4 H 4 O 5 ).3H 2 O is achieved using the gel diffusion technique. Multifaceted single crystals of size up to 4x3x3 mm 3 are obtained. X-Ray Diffraction (XRD) pattern of the grown crystal and the Fourier Transform Infra-Red (FTIR) spectrum in the range 400-4000 cm -1 are recorded. The vibrational bands corresponding to different functional groups are assigned. Thermal behavior of the material is investigated using Thermo Gravimetry (TG) and Differential Thermal Analysis (DTA). Thermal studies are indicative of a five-stage decomposition scheme. copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim. (orig.)

  4. Temperature fluctuations in a LiNbO 3 melt during crystal growth

    Science.gov (United States)

    Suzuki, Tetsuro

    2004-10-01

    Variations in temperature induced by forced convection on the surface of a LiNbO3 melt during crystal growth have been studied. Temperature measurements on the melt surface of single crystals growing (∅ 50 mm) at rotation rates of 15-40 rpm on an RF-heated Czochralski puller has revealed that the melt surface continuously alternates between a steady and unsteady state of flow. This was attributed to the intermittently turbulent flow mode at intermediate rotation rates. The fluctuation period is thought to depend on the thickness of its boundary layer. The boundary layer varies in thickness due to the melt flow, which stops as the interface moves toward the crystal and resumes once the interface reverts to its former position. By contrast, at above 60 rpm, the melt surface temperature drops without fluctuation, indicating that turbulent flow is dominant at faster rotation rates.

  5. Crystal growth and characterization of Tm doped mixed rare-earth aluminum perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Totsuka, Daisuke, E-mail: totsuka@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Nihon Kessho Kogaku Co., Ltd., 810-5 Nobe-cho, Tatebayashi, Gunma 374-0047 (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Sugiyama, Makoto; Fujimoto, Yutaka; Yokota, Yuui [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer (Lu{sub x}Gd{sub y}Y{sub 0.99-x-y}Tm{sub 0.01})AP single crystals were grown by the {mu}-PD method. Black-Right-Pointing-Pointer The grown crystals were single phase with perovskite structure (Pbnm). Significant segregation of Lu and Gd was detected in the growth direction. Black-Right-Pointing-Pointer Some absorption bands due to Tm{sup 3+}, Gd{sup 3+} and color centers were exhibited. Black-Right-Pointing-Pointer Radioluminescence spectra showed several emission peaks ascribed to Tm{sup 3+} and Gd{sup 3+}. -- Abstract: In this work, we present results of structural characterization and optical properties including radio luminescence of (Lu{sub x}Gd{sub y}Y{sub 0.99-x-y}Tm{sub 0.01})AP single crystal scintillators for (x, y) = (0.30, 0.19), (0, 0.19) and (0, 0) grown by the micro-pulling-down ({mu}-PD) method. The grown crystals were single phase materials with perovskite structure (Pbnm) as confirmed by XRD and had a good crystallinity. The distribution of the crystal constituents in growth direction was evaluated, and significant segregation of Lu and Gd was detected in (Lu{sub 0.30}Gd{sub 0.19}Y{sub 0.50}Tm{sub 0.01})AP sample. The crystals demonstrated 70% transmittance in visible wavelength range and some absorption bands due to Tm{sup 3+}, Gd{sup 3+} and color centers were exhibited in 190-900 nm. The radioluminescence measurement under X-ray irradiation demonstrated several emission peaks ascribed to 4f-4f transitions of Tm{sup 3+} and Gd{sup 3+}. The ratio of emission intensity in longer wavelength range was increased when Y was replaced by Lu or Gd.

  6. Ultra-high vacuum compatible induction-heated rod casting furnace.

    Science.gov (United States)

    Bauer, A; Neubauer, A; Münzer, W; Regnat, A; Benka, G; Meven, M; Pedersen, B; Pfleiderer, C

    2016-06-01

    We report the design of a radio-frequency induction-heated rod casting furnace that permits the preparation of polycrystalline ingots of intermetallic compounds under ultra-high vacuum compatible conditions. The central part of the system is a bespoke water-cooled Hukin crucible supporting a casting mold. Depending on the choice of the mold, typical rods have a diameter between 6 mm and 10 mm and a length up to 90 mm, suitable for single-crystal growth by means of float-zoning. The setup is all-metal sealed and may be baked out. We find that the resulting ultra-high vacuum represents an important precondition for processing compounds with high vapor pressures under a high-purity argon atmosphere up to 3 bars. Using the rod casting furnace, we succeeded to prepare large high-quality single crystals of two half-Heusler compounds, namely, the itinerant antiferromagnet CuMnSb and the half-metallic ferromagnet NiMnSb.

  7. Study of the reduction mechanism of ironsands with addition of blast furnace bag dust

    Science.gov (United States)

    Xing, Xiangdong; Chen, Yunfei; Liu, Yiran

    2018-02-01

    To improve the reduction properties of ironsands carbon-containing briquettes, the behavior of ironsand during reduction by the addition of blast furnace bag dust (BFBD) is studied using a high temperature resistance furnace, X-ray diffraction (XRD) analysis and scanning electron microscopy. Additionally, the reduction mechanism is discussed in this study. The results showed that the reduction level and compressive strength of ironsand carbon-containing briquettes could be promoted by increasing the proportion of BFBD. When the addition rate of BFBD was 31.25%, the metallization rate and compressive strength increased from 82.1% and 21.5 N/a to 91.4% and 172.5 N/a, respectively. Metallic iron reduced from BFBD particles favored the carbon gasification reaction, which enhanced the internal CO concentration, and then promoted the FeTiO3 reduction to Fe in ironsand. Meanwhile, a large amount of the liquid phase generated during the reduction process also favored Fe2+ diffusion, spread of iron joined crystals and the growth of crystals, which resulted in the improvement of the compressive strength of the ironsand carbon-containing briquettes.

  8. Nucleation and crystal growth behavior of nepheline in simulated high-level waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Amoroso, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Mcclane, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-26

    The Savannah River National Laboratory (SRNL) has been tasked with supporting glass formulation development and process control strategies in key technical areas, relevant to the Department of Energy’s Office of River Protection (DOE-ORP) and related to high-level waste (HLW) vitrification at the Waste Treatment and Immobilization Plant (WTP). Of specific interest is the development of predictive models for crystallization of nepheline (NaAlSiO4) in HLW glasses formulated at high alumina concentrations. This report summarizes recent progress by researchers at SRNL towards developing a predicative tool for quantifying nepheline crystallization in HLW glass canisters using laboratory experiments. In this work, differential scanning calorimetry (DSC) was used to obtain the temperature regions over which nucleation and growth of nepheline occur in three simulated HLW glasses - two glasses representative of WTP projections and one glass representative of the Defense Waste Processing Facility (DWPF) product. The DWPF glass, which has been studied previously, was chosen as a reference composition and for comparison purposes. Complementary quantitative X-ray diffraction (XRD) and optical microscopy confirmed the validity of the methodology to determine nucleation and growth behavior as a function of temperature. The nepheline crystallization growth region was determined to generally extend from ~ 500 to >850 °C, with the maximum growth rates occurring between 600 and 700 °C. For select WTP glass compositions (high Al2O3 and B2O3), the nucleation range extended from ~ 450 to 600 °C, with the maximum nucleation rates occurring at ~ 530 °C. For the DWPF glass composition, the nucleation range extended from ~ 450 to 750 °C with the maximum nucleation rate occurring at ~ 640 °C. The nepheline growth at the peak temperature, as determined by XRD, was between 35 - 75 wt.% /hour. A maximum nepheline growth rate of ~ 0.1 mm/hour at 700 °C was measured for the DWPF

  9. Effect of Gravity Level on the Particle Shape and Size During Zeolite Crystal Growth

    Science.gov (United States)

    Song, Hong-Wei; Ilebusi, Olusegun J.; Sacco, Albert, Jr.

    2003-01-01

    A microscopic diffusion model is developed to represent solute transport in the boundary layer of a growing zeolite crystal. This model is used to describe the effect of gravity on particle shape and solute distribution. Particle dynamics and crystal growth kinetics serve as the boundary conditions of flow and convection-diffusion equations. A statistical rate theory is used to obtain the rate of solute transport across the growing interface, which is expressed in terms of concentration and velocity of solute species. Microgravity can significantly decrease the solute velocity across the growing interface compared to its earth-based counterpart. The extent of this reduction highly depends on solute diffusion constant in solution. Under gravity, the flow towards the crystal enhances solute transport rate across the growing interface while the flow away from crystals reduces this rate, suggesting a non-uniform growth rate and thus an elliptic final shape. However, microgravity can significantly reduce the influence of flow and obtain a final product with perfect spherical shape. The model predictions compare favorably with the data of space experiment of zeolites grown in space.

  10. Growth of poly-crystalline silicon–germanium on silicon by aluminum-induced crystallization

    International Nuclear Information System (INIS)

    Lin, Jian-Yang; Chang, Pai-Yu

    2012-01-01

    The formation of poly-crystalline silicon–germanium films on single-crystalline silicon substrates by the method of aluminum-induced crystallization was investigated. The aluminum and germanium films were evaporated onto the single-crystalline silicon substrate to form an amorphous-germanium/aluminum/single-crystalline silicon structure that was annealed at 450 °C–550 °C for 0–3 h. The structural properties of the films were examined using x-ray diffraction, Raman spectroscopy and Auger electron spectroscopy. The x-ray diffraction patterns confirmed that the initial transition from an amorphous to a poly-crystalline structure occurs after 20 min of aluminum-induced crystallization annealing process at 450 °C. The micro-Raman spectral analysis showed that the aluminum-induced crystallization process yields a better poly-crystalline SiGe film when the film is annealed at 450 °C for 40 min. The growth mechanism of the poly-crystalline silicon–germanium by aluminum-induced crystallization was also studied and is discussed. - Highlights: ► Aluminum-induced poly-SiGe growth on Si substrates has been studied. ► Initial transition from a-SiGe to poly-SiGe occurs after 20-min AIC at 450 °C. ► Free Ge and Si atoms undergo inter-diffusion during AIC.

  11. Single crystal growth and optical properties of a transparent perovskite oxide LaInO3

    Science.gov (United States)

    Jang, Dong Hyun; Lee, Woong-Jhae; Sohn, Egon; Kim, Hyung Joon; Seo, Dongmin; Park, Ju-Young; Choi, E. J.; Kim, Kee Hoon

    2017-03-01

    Transparent LaInO3 single crystals have been grown using the optical floating zone method. Optimal growth, resulting in the highest optical transparency and best crystallinity, has been found at a growth speed of 15 mm/h and an O2 gas pressure of 10 bar. Under these conditions, single crystals as large as ˜4 × 4 mm2 have been obtained. Chemical compositions and structural analyses reveal that the resulting LaInO3 single crystal is stoichiometric without any impurity phase and forms an orthorhombic perovskite structure. Optical transmission spectra exhibit multiple optical transitions in a wide spectral range (0.5-4.2 eV). Although the main optical absorption occurs at ˜4.13 eV, weak absorption starts to develop from ˜1.4 eV, in agreement with an activation energy of ˜0.7 eV derived from electrical resistivity measurements. The dielectric constant ɛ is found to be 23.7 at room temperature. This LaInO3 single crystal can be used as a transparent perovskite substrate for growing oxide semiconductors with lattice constants close to ˜4.12 Å, such as doped BaSnO3.

  12. Growth, spectral, dielectric and antimicrobial studies on 4-piperidinium carboxylamide picrate crystals

    Science.gov (United States)

    Dhanabal, T.; Tharanitharan, V.; Amirthaganesan, G.; Dhandapani, M.

    2014-07-01

    Single crystal of 4-piperidinium carboxylamide picrate was grown by slow evaporation solution growth technique at ambient temperature. The average dimensions of grown crystal were 0.7 × 0.3 × 0.2 cm3. The solubility of the compound was analyzed using methanol and acetone. Optical property of the compound was ascertained by UV-visible absorption spectral study. The sharp and well defined Bragg peaks observed in the powder X-ray diffraction pattern confirm its crystallinity. The different kinds of protons and carbons in the compound were confirmed by 1H and 13C NMR spectral analyses. The presence of various functional groups in the compound was assigned through polarized Raman spectral study. The mechanical property of the crystal was measured by Vicker's microhardness test and the compound was found to be soft material. The dielectric constant and dielectric loss of the crystal decrease with increase in frequency. The antibacterial and antifungal activities of the crystal were studied by disc diffusion method and found that the compound shows good inhibition efficiency against various bacteria and fungi species.

  13. Growth, structural and magnetic characterization of Al-substituted barium hexaferrite single crystals

    International Nuclear Information System (INIS)

    Vinnik, D.A.; Zherebtsov, D.A.; Mashkovtseva, L.S.; Nemrava, S.; Bischoff, M.; Perov, N.S.; Semisalova, A.S.; Krivtsov, I.V.; Isaenko, L.I.; Mikhailov, G.G.; Niewa, R.

    2014-01-01

    Highlights: • Growth of large Al-substituted crystals BaFe 12−x Al x O 19. • Al-content controllable by flux composition. • Crystallographic site preference of Al unraveled. • Magnetic characterization depending on Al-content. - Abstract: Large single crystals of aluminum-substituted M-type barium hexaferrite BaFe 12−x Al x O 19 were obtained from carbonate flux. The Al content in the crystals can be controlled via the Al content of the flux up to x = 1.1 according to single crystal X-ray structure refinements. Al shows a distinct preference to substitute Fe on crystallographic sites with high coordination numbers by oxygen atoms, whereas no significant amounts of Al can be found on a tetrahedrally coordinated site. An increasing amount of the aluminum dopant results in a monotonous reduction of the Curie temperature from 440 to 415 °C and the saturation magnetization at room temperature from 68 to 57 emu/g for single crystal and from 61 to 53 emu/g for powder samples

  14. Crystal Growth Team in the Spacelab Payload Operations Control Center (SL POCC) During the STS-42

    Science.gov (United States)

    1992-01-01

    The primary payload for Space Shuttle Mission STS-42, launched January 22, 1992, was the International Microgravity Laboratory-1 (IML-1), a pressurized manned Spacelab module. The goal of IML-1 was to explore in depth the complex effects of weightlessness of living organisms and materials processing. Around-the-clock research was performed on the human nervous system's adaptation to low gravity and effects of microgravity on other life forms such as shrimp eggs, lentil seedlings, fruit fly eggs, and bacteria. Materials processing experiments were also conducted, including crystal growth from a variety of substances such as enzymes, mercury iodide, and a virus. The Huntsville Operations Support Center (HOSC) Spacelab Payload Operations Control Center (SL POCC) at the Marshall Space Flight Center (MSFC) was the air/ground communication channel used between the astronauts and ground control teams during the Spacelab missions. Featured is the Crystal Growth team in the SL POCC during STS-42, IML-1 mission.

  15. Numerical investigation of flows in Czochralski crystal growth by an axisymmetric lattice Boltzmann method

    Science.gov (United States)

    Peng, Y.; Shu, C.; Chew, Y. T.; Qiu, J.

    2003-03-01

    An alternative new method called lattice Boltzmann method (LBM) is applied in this work to simulate the flows in Czochralski crystal growth, which is one of the widely used prototypical systems for melt-crystal growth. The standard LBM can only be used in Cartesian coordinate system and we extend it to be applicable to this axisymmetric thermal flow problem, avoiding the use of three-dimensional LBM on Cartesian coordinate system. The extension is based on the following idea. By inserting position and time dependent source terms into the evolution equation of standard LBM, the continuity and NS equations on the cylindrical coordinate system [1] can be recovered. Our extension is validated by its application to the benchmark problem suggested by Wheeler [2].

  16. Numerical investigation of flows in Czochralski crystal growth by an axisymmetric lattice Boltzmann method

    CERN Document Server

    Peng, Y; Chew, Y T; Qiu, J

    2003-01-01

    An alternative new method called lattice Boltzmann method (LBM) is applied in this work to simulate the flows in Czochralski crystal growth, which is one of the widely used prototypical systems for melt-crystal growth. The standard LBM can only be used in Cartesian coordinate system and we extend it to be applicable to this axisymmetric thermal flow problem, avoiding the use of three-dimensional LBM on Cartesian coordinate system. The extension is based on the following idea. By inserting position and time dependent source terms into the evolution equation of standard LBM, the continuity and NS equations on the cylindrical coordinate system can be recovered. Our extension is validated by its application to the benchmark problem suggested by Wheeler .

  17. Numerical investigation of flows in Czochralski crystal growth by an axisymmetric lattice Boltzmann method

    International Nuclear Information System (INIS)

    Peng, Y.; Shu, C.; Chew, Y.T.; Qiu, J.

    2003-01-01

    An alternative new method called lattice Boltzmann method (LBM) is applied in this work to simulate the flows in Czochralski crystal growth, which is one of the widely used prototypical systems for melt-crystal growth. The standard LBM can only be used in Cartesian coordinate system and we extend it to be applicable to this axisymmetric thermal flow problem, avoiding the use of three-dimensional LBM on Cartesian coordinate system. The extension is based on the following idea. By inserting position and time dependent source terms into the evolution equation of standard LBM, the continuity and NS equations on the cylindrical coordinate system can be recovered. Our extension is validated by its application to the benchmark problem suggested by Wheeler

  18. Challenges in Melt Furnace Tests

    Science.gov (United States)

    Belt, Cynthia

    2014-09-01

    Measurement is a critical part of running a cast house. Key performance indicators such as energy intensity, production (or melt rate), downtime (or OEE), and melt loss must all be understood and monitored on a weekly or monthly basis. Continuous process variables such as bath temperature, flue temperature, and furnace pressure should be used to control the furnace systems along with storing the values in databases for later analysis. While using measurement to track furnace performance over time is important, there is also a time and place for short-term tests.

  19. Growth Temperature Dependence of Morphology of GaN Single Crystals in the Na-Li-Ca Flux Method

    Science.gov (United States)

    Wu, Xi; Hao, Hangfei; Li, Zhenrong; Fan, Shiji; Xu, Zhuo

    2018-02-01

    In this paper, the effect of growth temperature on the morphology and transparency of the GaN crystals obtained by the Li-Ca-added Na Flux method was studied. Addition of Li-Ca was attempted to control the growth habit and further improve transparency of GaN crystals. The samples with wurtzite structure of GaN were confirmed by the x-ray powder diffraction analysis. GaN single crystal with maximum size of about 6 mm was grown at 750°C. As the growth temperature was increased from 700°C to 850°C, the morphology of the crystals changed from pyramid to prism, and their surfaces became smooth. It was found that high growth temperature was beneficial to obtain a transparent crystal, but the evaporation of sodium would suppress its further growth. The E 2 (high) mode in the Raman spectra was at 568 cm-1, and the full-width at half-maximum values of this peak for the crystals obtained at 700°C, 750°C, 800°C, and 850°C were 7.5 cm-1, 10.3 cm-1, 4.4 cm-1, and 4.0 cm-1, respectively. It indicates that all the crystals are stress free and the transparent crystal grown at high temperature has high structural quality or low impurity concentrations.

  20. Kinetic study of nucleation and crystal growth during oxalic precipitation in the nuclear industry

    International Nuclear Information System (INIS)

    Andrieu, Murielle

    1999-01-01

    In spite of an extensive use in chemical industry, most of precipitation processes are based on global and empirical knowledge. However, in the recent years, fundamental and phenomenological theories have been developed and they can be used to better understand the mechanisms of precipitation of plutonium IV oxalate, which is a significant stage of the irradiated fuel reprocessing. For this reason, appropriate methods were developed to study nucleation and crystal growth kinetics in a nuclear environment under a wide range of operating conditions. Each phenomena was studied individually in order to reduce the free parameters of the System. This study bears on the oxalates of plutonium and elements which simulate plutonium behaviour during the precipitation, neodymium III and uranium IV. A compact apparatus of a specific construction was used for nucleation measurements in accordance with the Nielsen's method. The state of the mixing was characterised at the reactor scale (macro-mixing) and at molecular scale (micro-mixing). The experimental results for the studied oxalates are in good agreement with the Volmer and Weber's theory. We propose primary nucleation kinetic laws over a wide range of operating conditions (temperature, non-stoichiometric conditions, acidity...). An original method, using a high seed charge, was developed for the determination of crystal growth kinetics, in a batch crystallizer. The crystal growth rate is first order with respect to the supersaturation and the kinetic constant follows an Arrhenius type relation with activation energies of 14, 29 and 36 kJ.mol -1 for respectively neodymium III, uranium IV and plutonium IV oxalates. The overall growth process is surface integration controlled, with a screw dislocation mechanism. [fr

  1. Pattern transition between periodic Liesegang pattern and crystal growth regime in reaction-diffusion systems

    Science.gov (United States)

    Lagzi, István; Ueyama, Daishin

    2009-01-01

    The pattern transition between periodic precipitation pattern formation (Liesegang phenomenon) and pure crystal growth regimes is investigated in silver nitrate and potassium dichromate system in mixed agarose-gelatin gel. Morphologically different patterns were found depending on the quality of the gel, and transition between these typical patterns can be controlled by the concentration of gelatin in mixed gel. Effect of temperature and hydrodynamic force on precipitation pattern structure was also investigated.

  2. Growth and optical properties of RE-doped ternary rubidium lead chloride single crystals

    Czech Academy of Sciences Publication Activity Database

    Král, Robert; Nitsch, Karel; Babin, Vladimir; Šulc, J.; Jelínková, H.; Yokota, Y.; Yoshikawa, A.; Nikl, Martin

    2013-01-01

    Roč. 36, č. 2 (2013), s. 214-220 ISSN 0925- 3467 R&D Projects: GA MŠk LH12150 Institutional support: RVO:68378271 Keywords : rubidium lead chloride * crystal growth * micro-pulling-down method * rare earth doping * luminescence Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.075, year: 2013 http://www.sciencedirect.com/science/article/pii/S0925346713004710

  3. Optical and dielectric studies of KH2PO4 crystal influenced by organic ligand of citric acid and l-valine: A single crystal growth and comparative study

    Directory of Open Access Journals (Sweden)

    Mohd Anis

    Full Text Available In the present study pure, citric acid (CA and l-valine (LV doped potassium dihydrogen phosphate (KDP crystals have been grown with the aim to investigate the nonlinear optical applications facilitated by UV–visible, third order nonlinear optical (TONLO and dielectric properties. The structural parameters of grown crystals have been confirmed by single crystal X-ray diffraction analysis. The enhancement in optical transparency of KDP crystal due to addition of CA and LV has been examined within 200–900 nm by means of UV–visible spectral analysis. In addition, the transmittance data have been used to evaluate the effect of dopants on reflectance, refractive index and extinction coefficient of grown crystals in the visible region. The Z-scan analysis has been performed at 632.8 nm to identify the nature of photoinduced nonlinear refraction and nonlinear absorption in doped KDP crystals. The influence of π-bonded ligand of dopant CA and LV on TONLO susceptibility (χ3, refractive index (n2 and absorption coefficient (β of KDP crystals has been evaluated to discuss laser assisted device applications. The decrease in dielectric constant and dielectric loss of KDP crystal due to addition of CA and LV has been explored using the temperature dependent dielectric studies. Keywords: Crystal growth, Nonlinear optical materials, UV–visible studies, Z-scan analysis, Dielectric studies

  4. Transient from crystallization to fractal growth observed in both boar bile and SnI sub 2 vapour

    CERN Document Server

    Zhang Ji Zhong; Xie An Jian

    2003-01-01

    A visual transient of the growth mechanism from crystallization to fractal growth was observed clearly in a drop of boar bile. The growing crystals were replaced by treelike fractal structures during solidification of the sample. It is fascinating to compare the transient with the result observed in SnI sub 2 vapour. They were completely identical, and revealed that under certain conditions a linear growth could be transferred spontaneously into nonlinear growth. It may be possible to consider the transient as a 'bridge' between linear and nonlinear growth, and to develop a quantitative expression of transient dynamics.

  5. Crystal grain growth during room temperature high pressure Martensitic alpha to omega transformation in zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Velisavljevic, Nenad [Los Alamos National Laboratory; Chesnut, Gary N [Los Alamos National Laboratory; Stevens, Lewis L [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory

    2008-01-01

    Systematic increase in transition pressure with increase in interstitial impurities is observed for the martensitic {alpha} {yields} {omega} structural phase transition in Zr. Significant room temperature crystal grain growth is also observed for the two highest purity samples at this transition, while in the case of the lowest purity sample interstitial impurities obstruct grain growth even as the sample is heated to 1279 K. Our results show the importance of impurities in controlling structural phase stability and other mechanical properties associated with the {alpha} {yields} {omega} structural phase transition.

  6. Phase-field study of crystal growth in three-dimensional capillaries: Effects of crystalline anisotropy

    Science.gov (United States)

    Debierre, Jean-Marc; Guérin, Rahma; Kassner, Klaus

    2016-07-01

    Phase-field simulations are performed to explore the thermal solidification of a pure melt in three-dimensional capillaries. Motivated by our previous work for isotropic or slightly anisotropic materials, we focus here on the more general case of anisotropic materials. Different channel cross sections are compared (square, hexagonal, circular) to reveal the influence of geometry and the effects of a competition between the crystal and the channel symmetries. In particular, a compass effect toward growth directions favored by the surface energy is identified. At given undercooling and anisotropy, the simulations generally show the coexistence of several growth modes. The relative stability of these growth modes is tested by submitting them to a strong spatiotemporal noise for a short time, which reveals a subtle hierarchy between them. Similarities and differences with experimental growth modes in confined geometry are discussed qualitatively.

  7. Growth rate anisotropy and absorption studies on β-BaB 2O 4 single crystals grown by the top-seeded solution growth technique

    Science.gov (United States)

    Bhatt, Rajeev; Ganesamoorthy, S.; Bhaumik, Indranil; Karnal, A. K.; Wadhawan, V. K.

    2007-03-01

    Beta barium borate (β-BaB2O4; BBO) single crystals have been grown from Na2O flux by the TSSG technique and the observed growth rate anisotropy is reported. The symmetrical conoscopic interference pattern on the c-cut plate confirmed strain-free and optical homogeneity of the crystals. The observed growth habits of as-grown crystals are explained using crystal growth theories. The relative growth rate along different crystallographic directions of BBO can be described by R[100] = R[010] > R[001]. The absorption measurements show a nearly 9 nm shift in fundamental absorption edges in X and Z cut samples. Band gap energies measured were 6.45 and 6.2 eV along the X and Z directions, respectively. The absorption spectra near the fundamental absorption edges (AE) follow Urbach's rule.

  8. Crystal Growth of Ca3Nb(Ga1−xAlx3Si2O14 Piezoelectric Single Crystals with Various Al Concentrations

    Directory of Open Access Journals (Sweden)

    Yuui Yokota

    2015-08-01

    Full Text Available Ca3Nb(Ga1−xAlx3Si2O14 (CNGAS single crystals with various Al concentrations were grown by a micro-pulling-down (µ-PD method and their crystal structures, chemical compositions, crystallinities were investigated. CNGAS crystals with x = 0.2, 0.4 and 0.6 indicated a single phase of langasite-type structure without any secondary phases. In contrast, the crystals with x = 0.8 and 1 included some secondary phases in addition to the langasite-type phase. Lattice parameters, a- and c-axes lengths, of the langasite-type phase systematically decreased with an increase of Al concentration. The results of chemical composition analysis revealed that the actual Al concentrations in as-grown crystals were almost consistent with the nominal compositions. In addition, there was no large segregation of each cation along the growth direction.

  9. The crystalline quality distribution in CdZnTe single crystal correlated to the interface shape during growth

    Energy Technology Data Exchange (ETDEWEB)

    Azoulay, M.; Rotter, S.; Gafni, G. (Soreq Nuclear Research Center, Yavne (Israel)); Roth, M. (School of Applied Science and Technology, Hebrew Univ. of Jerusalem (Israel))

    1992-02-01

    Crystalline quality of CdZnTe single crystals grown by the vertical gradient freeze (VGF) method has been evaluated using the double crystal rocking curve (DCRC) analysis and etch pits density (EPD) measurements. The full width at half maximum (HWHM) values of the DCRCs vary within 40% while the EPD values range from 2 to 8 x 10{sup 4} cm{sup -2} along the crystal growth axis. Best results are obtained for the central part of the crystals, where the growth interface exhibits a nearly planar shape. The results obtained have been used for practical implications with regard to the use of CdZnTe crystals as a substrate material for HgCdTe thin films growth. (orig.).

  10. Arc -furnace Flicker Compensation in Ethiopia.

    African Journals Online (AJOL)

    series capacitors nor the translater scheme is appli- cable where more ... The arc furnace is of conventional design. The furnace ... power of the furnace. This reactor had three tappings and a short-circuiting switch. REQUIREMENTS OF THE COMPENSATOR. The fluctuations could be caused by the furnace on whichever ...

  11. Fossil fuel furnace reactor

    Science.gov (United States)

    Parkinson, William J.

    1987-01-01

    A fossil fuel furnace reactor is provided for simulating a continuous processing plant with a batch reactor. An internal reaction vessel contains a batch of shale oil, with the vessel having a relatively thin wall thickness for a heat transfer rate effective to simulate a process temperature history in the selected continuous processing plant. A heater jacket is disposed about the reactor vessel and defines a number of independent controllable temperature zones axially spaced along the reaction vessel. Each temperature zone can be energized to simulate a time-temperature history of process material through the continuous plant. A pressure vessel contains both the heater jacket and the reaction vessel at an operating pressure functionally selected to simulate the continuous processing plant. The process yield from the oil shale may be used as feedback information to software simulating operation of the continuous plant to provide operating parameters, i.e., temperature profiles, ambient atmosphere, operating pressure, material feed rates, etc., for simulation in the batch reactor.

  12. crystal

    Science.gov (United States)

    Yu, Yi; Huang, Yisheng; Zhang, Lizhen; Lin, Zhoubin; Sun, Shijia; Wang, Guofu

    2014-07-01

    A Nd3+:Na2La4(WO4)7 crystal with dimensions of ϕ 17 × 30 mm3 was grown by the Czochralski method. The thermal expansion coefficients of Nd3+:Na2La4(WO4)7 crystal are 1.32 × 10-5 K-1 along c-axis and 1.23 × 10-5 K-1 along a-axis, respectively. The spectroscopic characteristics of Nd3+:Na2La4(WO4)7 crystal were investigated. The Judd-Ofelt theory was applied to calculate the spectral parameters. The absorption cross sections at 805 nm are 2.17 × 10-20 cm2 with a full width at half maximum (FWHM) of 15 nm for π-polarization, and 2.29 × 10-20 cm2 with a FWHM of 14 nm for σ-polarization. The emission cross sections are 3.19 × 10-20 cm2 for σ-polarization and 2.67 × 10-20 cm2 for π-polarization at 1,064 nm. The fluorescence quantum efficiency is 67 %. The quasi-cw laser of Nd3+:Na2La4(WO4)7 crystal was performed. The maximum output power is 80 mW. The slope efficiency is 7.12 %. The results suggest Nd3+:Na2La4(WO4)7 crystal as a promising laser crystal fit for laser diode pumping.

  13. Synthesis, growth, structural, optical, thermal, dielectric and mechanical studies of an organic guanidinium p-nitrophenolate crystal

    Science.gov (United States)

    Dhavamurthy, M.; Peramaiyan, G.; Mohan, R.

    2014-08-01

    Guanidinium p-nitrophenolate (GUNP), a novel organic compound, was synthesized and crystals were grown from methanol solution by a slow evaporation solution growth technique. A single crystal X-ray diffraction study elucidated the crystal structure of GUNP belonging to the orthorhombic crystal system with space group Pnma. Thermal studies revealed that the GUNP crystal is thermally stable up to 192 °C. The lower cut-off wavelength of GUNP was found to be 505 nm by UV-vis-NIR spectral studies. The luminescence properties of the GUNP crystal were investigated. The three independent tensor coefficients ε11, ε22 and ε33 of the dielectric permittivity were calculated. The mechanical properties of the grown crystal were studied by Vickers' microhardness hardness technique.

  14. Exploring growth conditions and Eu2+ concentration effects for KSr2I5:Eu scintillator crystals II: Ø 25 mm crystals

    Science.gov (United States)

    Stand, L.; Zhuravleva, M.; Johnson, J.; Koschan, M.; Wu, Y.; Donnald, S.; Vaigneur, K.; Lukosi, E.; Melcher, C. L.

    2018-02-01

    Europium doped potassium strontium iodide is a very promising scintillator for national security applications due to its ease of growth and excellent scintillation properties. For this work the fast crystal growth and scintillation properties of 1-inch diameter single crystals of KSr2I5:Eu2+ (KSI:Eu) were investigated. We focused our efforts on optimizing the growth parameters required to produce one-inch diameter crystals without decreasing the previously reported fast pulling rate of 5 mm/h. Cracking was minimized by replacing the quartz ampoules with carbon coated quartz ampoules; thus, several crack free single crystals of KSI with varying Eu2+ concentrations were grown, including a Ø 1″ by 6″ long boule with 2.5% Eu. The maximum achievable performance of each crystal was measured using small 0.012 cm3 specimens. The volumetric dependencies of the light yield, energy resolution and decay time were evaluated using KSI:Eu 2% specimens with volumes ranging from 0.012 cm3 to 18 cm3. For large volumes (≥ 9 cm3), the performance was comparable to other high performing scintillators, with light yields up to 78,200 ph/MeV and energy resolutions as good as 3.2% at 662 keV. The initial version of a hermetic package has been developed, and the stability of the sealed crystal is promising.

  15. Acceleration of Crystal Growth of Amorphous Griseofulvin by Low-Concentration Poly(ethylene oxide): Aspects of Crystallization Kinetics and Molecular Mobility.

    Science.gov (United States)

    Shi, Qin; Zhang, Chen; Su, Yuan; Zhang, Jie; Zhou, Dongshan; Cai, Ting

    2017-07-03

    This study aims to investigate the crystallization behavior and molecular dynamics of amorphous griseofulvin (GSF) in the presence of low-concentration poly(ethylene oxide) (PEO). We observe that the addition of 3% w/w PEO remarkably increases the crystal growth rate of GSF by two orders of magnitude in both the supercooled liquid and glassy states. The liquid dynamics of amorphous GSF in the presence and absence of PEO are characterized by dielectric spectroscopy. With an increase of the PEO content, the α-relaxation times of the systems decrease, indicating the increase of global molecular mobility. The couplings between molecular mobility and crystallization kinetics of GSF systems show strong time-dependences below T g . The overlapping of α-relaxation times of GSF in presence and absence of PEO as a function of T g /T suggest the "plasticization" effect of PEO additives. However, the crystallization kinetics of amorphous GSF containing low-concentration PEO do not overlap with those of pure GSF on a T g /T scale. The remarkable accelerating effect of crystal growth of amorphous GSF by low-concentration PEO can be partially attributed to the increase of global mobility. The high segmental mobility of PEO is expected to strongly affect the crystal growth rates of GSF. These findings are relevant for understanding and predicting the physical stability of amorphous pharmaceutical solid dispersions.

  16. Thermodynamical properties of III-V nitrides and crystal growth of GaN at high N 2 pressure

    Science.gov (United States)

    Porowski, S.; Grzegory, I.

    1997-06-01

    In this paper, thermodynamical properties of AIN, GaN and InN are considered. It is shown that significant differences in melting conditions, thermal stability and solubilities in liquid group III metals lead to different possibilities of growing crystals from high temperature solutions, at N 2 pressure up to 20 kbar. It is shown that the best conditions for crystal growth at available pressure and temperature conditions can be achieved for GaN. High quality 6-10 mm single crystals of GaN have been grown at high N 2 pressure in 60-150 h processes. The mechanisms of nucleation and growth of GaN crystals are discussed on the basis of the experimental results. The crystallization of AlN is less efficient due to relatively low solubility of AlN in liquid Al. Possibility for the growth of InN crystals is strongly limited since this compound loses its stability at T > 600°C, even at 2 GPa N 2 pressure. The crystals of GaN grown at high pressure are the first crystals of this material used for homoepitaxial layer deposition. Both MOCVD and MBE methods have been successfully applied. Structural, electrical and optical properties of both GaN single crystals and homoepitaxial layers are reviewed.

  17. Crystal growth and scintillation properties of Tm:K.sub.2./sub.NaLuF.sub.6./sub..

    Czech Academy of Sciences Publication Activity Database

    Abe, N.; Yanagida, T.; Yokota, Y.; Maeo, S.; Pejchal, Jan; Fujimoto, Y.; Furuya, Y.; Tanaka, H.; Kawaguchi, N.; Fukuda, K.; Chani, V.; Kamada, K.; Nikl, Martin; Yoshikawa, A.

    2010-01-01

    Roč. 32, č. 5 (2010), s. 589-594 ISSN 0925- 3467 Grant - others:AV ČR(CZ) M100100910 Institutional research plan: CEZ:AV0Z10100521 Keywords : fluoride, * single crystal * crystal growth from the melt * Tm 3+ luminescence * scintillator Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.679, year: 2010

  18. The growth of benzophenone crystals by Sankaranarayanan–Ramasamy (SR) method and slow evaporation solution technique (SEST): A comparative investigation

    International Nuclear Information System (INIS)

    Senthil Pandian, M.; Boopathi, K.; Ramasamy, P.; Bhagavannarayana, G.

    2012-01-01

    Highlights: ► Benzophenone single crystal was grown by Sankaranarayanan–Ramasamy method which has the sizes of 1060 mm length and 55 mm diameter for the first time. ► The conventional and SR-grown benzophenone crystals were characterized and compared using HRXRD, etching, laser damage threshold, microhardness, UV-transmittance, birefringence and dielectric analysis. ► The SR-grown benzophenone crystal has higher LDT, microhardness, transparency, dielectric permittivity, birefringence and lower FWHM, EPD, dielectric loss than the crystal grown by conventional method. ► The probable reason for higher crystalline perfection in SR-grown crystal was discussed. -- Abstract: Longest unidirectional〈1 0 0〉 benzophenone (BP) crystal having dimension of 1060 mm length and 55 mm diameter was grown by Sankaranarayanan–Ramasamy method. The growth rate was measured by monitoring the elevation of the crystal–solution interface at different temperatures. The high resolution X-ray diffraction and etching measurements indicate that the unidirectional grown benzophenone crystal has good crystalline perfection and less density of defects. The optical damage threshold of SEST and SR grown BP crystals has been investigated and found that the SR grown benzophenone crystal has higher laser damage threshold value than the conventional method grown crystal. Microhardness measurement shows that crystals grown by SR method have a higher mechanical stability than the crystals grown by SEST method. Dielectric permittivity and birefringence are high in SR grown crystal compared to SEST grown BP crystal. The UV–vis-NIR results show that SR method grown crystal exhibits 7% higher transmittance as against crystals grown by conventional method.

  19. Investigating the crystal growth behavior of biodegradable polymer blend thin films using in situ atomic force microscopy

    CSIR Research Space (South Africa)

    Malwela, T

    2014-01-01

    Full Text Available This article reports the crystal growth behavior of biodegradable polylactide (PLA)/poly[(butylene succinate)-co-adipate] (PBSA) blend thin films using atomic force microscopy (AFM). Currently, polymer thin films have received increased research...

  20. The impact of nanoclay on the crystal growth kinetics and morphology of biodegradable poly(ethylene succinate) composite

    CSIR Research Space (South Africa)

    Bandyopadhyay, J

    2012-07-01

    Full Text Available The impact of nanoclay on the isothermal crystal growth kinetics and morphology of biodegradable poly(ethylene succinate) (PES) is reported. A PES composite (PESNC) containing 5 wt% organically modified montmorillonite, was prepared via solvent...