WorldWideScience

Sample records for crystal growth thermal

  1. 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.)

  2. 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.

  3. 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.

  4. 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.

  5. 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 ...

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.)

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Computational analysis of heat transfer, thermal stress and dislocation density during resistively Czochralski growth of germanium single crystal

    Science.gov (United States)

    Tavakoli, Mohammad Hossein; Renani, Elahe Kabiri; Honarmandnia, Mohtaram; Ezheiyan, Mahdi

    2018-02-01

    In this paper, a set of numerical simulations of fluid flow, temperature gradient, thermal stress and dislocation density for a Czochralski setup used to grow IR optical-grade Ge single crystal have been done for different stages of the growth process. A two-dimensional steady state finite element method has been applied for all calculations. The obtained numerical results reveal that the thermal field, thermal stress and dislocation structure are mainly dependent on the crystal height, heat radiation and gas flow in the growth system.

  2. 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.

  3. An analytical approach to thermal modeling of Bridgman type crystal growth: One dimensional analysis. Computer program users manual

    Science.gov (United States)

    Cothran, E. K.

    1982-01-01

    The computer program written in support of one dimensional analytical approach to thermal modeling of Bridgman type crystal growth is presented. The program listing and flow charts are included, along with the complete thermal model. Sample problems include detailed comments on input and output to aid the first time user.

  4. 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.

  5. Growth, structural, optical, thermal and mechanical studies on 4-Aminopyridinium monophthalate: A novel nonlinear optical crystal

    Science.gov (United States)

    Marudhu, G.; Krishnan, S.; Palanichamy, M.

    2016-03-01

    A novel nonlinear optical crystal of 4-Aminopyridinium monophthalate (4-APMP) was grown by slow evaporation technique using methanol as solvent. Single crystal X-ray diffraction analysis confirms that the grown crystal belongs to orthorhombic system. The presence of functional groups was qualitatively determined by FTIR analysis. The optical absorption studies reveal very low absorption in the entire visible region. The fluorescence emission spectrum shows the emission is in blue region. The thermal stability of the grown crystal is found to be around 197.2 °C. The SHG efficiency of the grown crystal is found to be 1.1 times than that of KDP crystals.

  6. Influence of Crucible Thermal Conductivity on Crystal Growth in an Industrial Directional Solidification Process for Silicon Ingots

    Directory of Open Access Journals (Sweden)

    Zaoyang Li

    2016-01-01

    Full Text Available We carried out transient global simulations of heating, melting, growing, annealing, and cooling stages for an industrial directional solidification (DS process for silicon ingots. The crucible thermal conductivity is varied in a reasonable range to investigate its influence on the global heat transfer and silicon crystal growth. It is found that the crucible plays an important role in heat transfer, and therefore its thermal conductivity can influence the crystal growth significantly in the entire DS process. Increasing the crucible thermal conductivity can shorten the time for melting of silicon feedstock and growing of silicon crystal significantly, and therefore large thermal conductivity is helpful in saving both production time and power energy. However, the high temperature gradient in the silicon ingots and the locally concave melt-crystal interface shape for large crucible thermal conductivity indicate that high thermal stress and dislocation propagation are likely to occur during both growing and annealing stages. Based on the numerical simulations, some discussions on designing and choosing the crucible thermal conductivity are presented.

  7. 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.

  8. Thermally controlled growth of surface nanostructures on ion-modified AIII-BV semiconductor crystals

    Science.gov (United States)

    Trynkiewicz, Elzbieta; Jany, Benedykt R.; Wrana, Dominik; Krok, Franciszek

    2018-01-01

    The primary motivation for our systematic study is to provide a comprehensive overview of the role of sample temperature on the pattern evolution of several AIII-BV semiconductor crystal (001) surfaces (i.e., InSb, InP, InAs, GaSb) in terms of their response to low-energy Ar+ ion irradiation conditions. The surface morphology and the chemical diversity of such ion-modified binary materials has been characterized by means of scanning electron microscopy (SEM). In general, all surface textures following ion irradiation exhibit transitional behavior from small islands, via vertically oriented 3D nanostructures, to smoothened surface when the sample temperature is increased. This result reinforces our conviction that the mass redistribution of adatoms along the surface plays a vital role during the formation and growth process of surface nanostructures. We would like to emphasize that this paper addresses in detail for the first time the topic of the growth kinetics of the nanostructures with regard to thermal surface diffusion, while simultaneously offering some possible approaches to supplementing previous studies and therein gaining a new insight into this complex issue. The experimental results are discussed with reference to models of the pillars growth, abutting on preferential sputtering, the self-sustained etch masking effect and the redeposition process recently proposed to elucidate the observed nanostructuring mechanism.

  9. Crystal growth, structural, thermal and mechanical behavior of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) single crystals

    Science.gov (United States)

    Mahadevan, M.; Ramachandran, K.; Anandan, P.; Arivanandhan, M.; Bhagavannarayana, G.; Hayakawa, Y.

    2014-12-01

    Single crystals of L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) have been grown successfully from the solution of L-arginine and 4-nitrophenol. Slow evaporation of solvent technique was adopted to grow the bulk single crystals. Single crystal X-ray diffraction analysis confirms the grown crystal has monoclinic crystal system with space group of P21. Powder X-ray diffraction analysis shows the good crystalline nature. The crystalline perfection of the grown single crystals was analyzed by HRXRD by employing a multicrystal X-ray diffractometer. The functional groups were identified from proton NMR spectroscopic analysis. Linear and nonlinear optical properties were determined by UV-Vis spectrophotometer and Kurtz powder technique respectively. It is found that the grown crystal has no absorption in the green wavelength region and the SHG efficiency was found to be 2.66 times that of the standard KDP. The Thermal stability of the crystal was found by obtaining TG/DTA curve. The mechanical behavior of the grown crystal has been studied by Vicker's microhardness method.

  10. A thermal model for czochralski silicon crystal growth with an axial magnetic field

    Science.gov (United States)

    Hjellming, L. N.

    1990-07-01

    This paper presents a thermal model for molten silicon in a Czochralski crystal puller system with an applied uniform axial magnetic field. The melt depth is treated as continually decreasing, which affects the thermal environment of the melt and crystal. The radiative heat loss and the input heat flux are treated as functions of time, with a constraint placed on the heat lost to the crystal from the melt. As the melt motion reaches a steady state rapidly, the temperature and flow fields are treated as instantaneously steady at each melt depth. The heat transport is a mixture of conduction and convection, and by considering the crystal and crucible to be rotating with the same angular velocity, the flows driven by buoyancy and thermocapillarity are isolated and provide the convective heat transport in the melt for the range of magnetic field strengths 0.2 ≤ B ≤ 1.0T.

  11. Growth, structural, thermal and optical studies of deuterated L-Arginine phosphate (dLAP) single crystals

    International Nuclear Information System (INIS)

    Haja Hameed, A.S.; Ravi, G.; Nixon Azariaha, A.; Ramasamy, P.

    2001-01-01

    L-arginine phosphate (LAP) and deuterated L-arginine phosphate(dLAP) are promising non linear optical materials having good non linear coefficient, high damage threshold and less hygroscopic nature as compared to potassium dihydrogen phosphate (KDP). Due to the significant absorptions in the near infrared in the pure LAP, its deuterated analog (dLAP) crystals have been grown. The presence of deuterium in dLAP shifts this absorption by 3%. This crystals are grown from the solvent of heavy water (D 2 O) by slow cooling method. The growth conditions for the growth of monoclinic dLAP crystals are optimized by adjusting the growth parameters, such as pH, temperature etc. The grown crystals are morphologically compared with the pure LAP crystals. The variation of lattice parameters of dLAP crystal with pure LAP is found from the X-ray powder diffraction studies. The thermal behaviour and molecular vibrations of dLAP are reported from DT and TG and FTIR studies. (author)

  12. Growth, thermal and laser properties of Yb:YxLu1−xVO4 mixed crystal

    International Nuclear Information System (INIS)

    Zhong, Degao; Teng, Bing; Kong, Weijin; Li, Jianhong; Zhang, Shiming; Li, Yuyi; Cao, Lifeng; Yang, Liting; He, Linxiang; Huang, Wanxia

    2015-01-01

    New mixed crystal of Yb: Y 0.78 Lu 0.22 VO 4 with Yb ion concentration of 0.3 at% was grown by Czochralski method. Transmission synchrotron X-ray topography implies that this mixed crystal follows a rotational growth pattern. Crystal structure of this crystal was determined by X-ray diffraction. It showed that this crystal possesses a tetragonal zircon structure (ZrSiO 4 , space group I41/amd), as YVO 4 and LuVO 4 do. Thermal properties of this crystal were characterized by measuring its specific heat, thermal expansion coefficients and thermal conductivities. The specific heat was determined to be 0.500 J g −1 K −1 at 293 K. The average linear thermal expansion coefficients were calculated to be α 11 = 1.73 × 10 −6 K −1 and α 33 = 9.43 × 10 −6 K −1 , over the temperature range of 300–777 K. The thermal conductivities were calculated to be κ 11 = 5.47 W m −1 K −1 and κ 33 = 6.64 W m −1 K −1 at 303 K. Continuous-wave (cw) laser test on Yb: Y 0.78 Lu 0.22 VO 4 was conducted at room temperature in the wavelength range of 1035.7–1048.3 nm, and a 13.5% optical-to-optical efficiency was achieved. The good thermal properties of Yb:Y 0.78 Lu 0.22 VO 4 mixed crystal and its attractive cw laser performance make it very suitable for practical applications. - Highlights: • New Yb:Y 0.78 Lu 0.22 VO 4 mixed laser crystals were grown. • The thermal expansion, thermal diffusivity and specific heat were measured. • Cw laser operation was realized at room temperature in the range of 1035.7–1048.3 nm

  13. Optimized Pyroelectric Vidicon Thermal Imager. Volume II. Improper Ferroelectric Crystal Growth.

    Science.gov (United States)

    1980-09-01

    and Identify by block number) §Complete dielectric, pyroelectric, and thermal characterizations of Fe3B"O rl, CuBO "C1 and Mn"B’O ’ I were performed...by molecul*Nngineering tech- niques exhibited the rich potential in this family of pyr lectrics for de - signing materials to meet specific device...to pursue these two growth avenues simultaneously. As described below, these efforts led to development of novel synthesis and growth methods and

  14. 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.

  15. Crystal growth, vibrational, optical, thermal and theoretical studies of a nonlinear optical material: 2-Methyl 3,5-dinitrobenzoic acid

    Energy Technology Data Exchange (ETDEWEB)

    Sangeetha, K. [Department of Physics, Sri Sarada College for Women, Salem-16 (India); Guru Prasad, L. [Department of Science & Humanities, M. Kumarasamy College of Engineering, Karur (India); Mathammal, R. [Department of Physics, Sri Sarada College for Women, Salem-16 (India)

    2016-11-15

    Single crystals of 2-methyl 3,5-dinitro benzoic acid with reasonable size have been grown by slow evaporation solution growth method using ethanol as solvent. Quantum chemical calculation of 2-methyl 3,5-Dinitro benzoic acid was carried out by using DFT/B3LYP/6-31+G(d,p) method. The powder X-ray diffraction pattern was recorded and indexed. Both the experimental and theoretical vibrational spectrum validates the presence of functional groups. Polarizability, first order hyperpolarizability and the electric dipole moment values have been computed theoretically. The {sup 1}H and {sup 13}C NMR chemical shift of the molecule was calculated and compared with experimental results. TG/DSC analysis has been employed to understand the thermal and physio-chemical stability of the title compound. Frequency conversion property of the crystal was tested by Kurtz and Perry method. Optical absorption behavior of the grown crystal was examined by recording the optical spectrum and band gap energy was also estimated. The calculated HOMO and LUMO energy shows the charge transfer nature of the molecule.

  16. 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.

  17. Growth, structural, optical and thermal properties of a new semiorganic NLO crystal: L-prolyl mercury (II) chloride

    Science.gov (United States)

    Prabu, P.; Vijayabhaskaran, B.; Vasuki, G.; Ramachandra Raja, C.

    2018-01-01

    A new semiorganic crystal L-Prolyl Mercury (II) Chloride (LPMC), with molecular formula C5H7Cl2Hg NO2 has been grown from aqueous solution by employing slow evaporation technique. The crystal structure of LPMC has been determined from single crystal X-ray diffraction data and it crystallizes with two independent molecules in the asymmetric unit. The LPMC crystallizes in orthorhombic system with space group P212121, cell parameters a = 7.1638 (6) Å, b = 13.5231 (14) Å, c = 18.5866 (18) Å, α = 90°, β = 90° and γ = 90°. The vibrations of functional groups were studied by FT-IR and FT-Raman analysis. The chemical environment of carbon and hydrogen in the grown crystal was confirmed by nuclear magnetic resonance (NMR) studies. The thermal stability of the compound was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) and the crystal is found to have been stable up to 180 °C. Ultraviolet-visible-Near infrared (UV-vis-NIR) spectral analysis reveals that the crystal is transparent in the wavelength range of 250-1100 nm. The second harmonic generation (SHG) efficiency of LPMC crystal was determined after applying Kurtz and Perry powder test. The SHG efficiency is 1.257 times that of potassium dihydrogen phosphate (KDP).

  18. Thermal node of the growth vessel of apparatus of large-sized crystals of germanium growing by the immersible pivoted shaper method

    International Nuclear Information System (INIS)

    Bogomaz, A.V.; Krytskaja, T.V.; Karpenko, A.V.

    2013-01-01

    The construction of a thermal knot of the growth vessel of apparatus of large-sized crystals of germanium growing by the immersible pivoted shaper method is developed and tested. In a construction as a bowl material carbon and carbon-carbon composite bodied by pyrolytic carbon are used. Series of advantages of bowls from carbon-carbon composite material in the part of assurance of the given allocation of temperature on a surface of a bowl, heightening of a mechanical strength and fraction soot impurities lowering in a crystal is fixed. In experimental-industrial conditions crystals of germanium in diameter to 420 mm with high optical characteristic are received

  19. 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 ...

  20. Growth, crystalline perfection, optical, thermal, laser damage threshold and electrical characterization of melaminium levulinate monohydrate single crystal

    Science.gov (United States)

    Sivakumar, N.; Kanagathara, N.; Bhagavannarayana, G.; Kalainathan, S.; Anbalagan, G.

    2015-09-01

    Equimolar amounts of melamine and levulinic acid results an organic crystal of melaminium levulinate monohydrate (MLM) at room temperature. MLM belongs to a monoclinic crystal structure having P21/c space group which was confirmed by single crystal X-ray diffraction study. Functional groups present in the MLM crystal were identified by FT-IR spectral study. HRXRD study dictates the quality of MLM crystal. UV-visble spectrum of MLM reveals the lower cut-off wavelength of 293 nm with 55% optical transparency and optical band gap was found to be 4.20 eV for the prominent plane (1 0 -1). Refractive indices for the three axes of MLM crystal were found to be nx=2.6, ny=2.4 and nz=2.2 respectively. Further the thermal stability and melting point of MLM crystal were investigated by TG/DTA study. Dielectric permittivity tensor components were estimated for the planes (1 0 -1), (0 1 0) and (1 1 1) respectively. The thermal conductivity of the crystal by Wiedemann-Franz law was found to be 5.99×10-11 W/mK at 70 °C. LDT value (2.84 GW/cm2) of MLM was estimated for laser optical device applications.

  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. Growth, structural, optical, thermal and laser damage threshold studies of an organic single crystal: 1,3,5 – triphenylbenzene (TPB)

    International Nuclear Information System (INIS)

    Raja, R. Subramaniyan; Babu, G. Anandha; Ramasamy, P.

    2016-01-01

    Good quality single crystals of pure hydrocarbon 1,3,5-Triphenylbenzene (TPB) have been successfully grown using toluene as a solvent using controlled slow cooling solution growth technique. TPB crystallizes in orthorhombic structure with the space group Pna2 1 . The structural perfection of the grown crystal has been analysed by high resolution X-ray diffraction measurements. The range and percentage of the optical transmission are ascertained by recording the UV-vis spectrum. Thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. Powder second harmonic generation studies were carried out to explore its NLO properties. Laser damage threshold value has been determined using Nd:YAG laser operating at 1064 nm.

  3. Growth, structural, optical, thermal and laser damage threshold studies of an organic single crystal: 1,3,5 – triphenylbenzene (TPB)

    Energy Technology Data Exchange (ETDEWEB)

    Raja, R. Subramaniyan; Babu, G. Anandha; Ramasamy, P., E-mail: E-mail-ramasamyp@ssn.edu.in [Department of Physics, SSN College of Engineering, Kalavakkam,Tamilnadu-603110 (India)

    2016-05-23

    Good quality single crystals of pure hydrocarbon 1,3,5-Triphenylbenzene (TPB) have been successfully grown using toluene as a solvent using controlled slow cooling solution growth technique. TPB crystallizes in orthorhombic structure with the space group Pna2{sub 1}. The structural perfection of the grown crystal has been analysed by high resolution X-ray diffraction measurements. The range and percentage of the optical transmission are ascertained by recording the UV-vis spectrum. Thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. Powder second harmonic generation studies were carried out to explore its NLO properties. Laser damage threshold value has been determined using Nd:YAG laser operating at 1064 nm.

  4. Effect of Nickel sulphate on Growth, Structural, Optical, Mechanical and thermal properties of L-alanine Single Crystals (LANS)

    Science.gov (United States)

    Jothimani, R.; Selvarajan, P.

    2017-08-01

    The nonlinear optical materials find excellent place in frequency conversion, optical telecommunication, image processing, optical computing, and data storage. Due to possessing chiral symmetry and nature of crystallize in noncentro-symmetric space groups, the amino acids are applicable in NLO applications. A transparent nickel sulphate admixtured L-alanine crystal has been developed by solution method. X ray diffraction analysis depicts the orthorhombic crystal system of the sample. NLO efficiency of the sample was found to be highly pronounced compare to KDP. An enhanced linear optical property of the sample shows its suitability for NLO applications. Thermal behaviour of the sample was found by TGA/DTA analysis. Hardness parameters were also found for the sample by microhardness measurements. Laser damage threshold were also measured using Nd: YAG laser.

  5. 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

  6. 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...

  7. Growth, optical, thermal, mechanical and dielectric studies of sodium succinate hexahydrate (β phase) single crystal: A promising third order NLO material

    Science.gov (United States)

    Mageshwari, P. S. Latha; Priya, R.; Krishnan, S.; Joseph, V.; Das, S. Jerome

    2016-11-01

    A third order nonlinear optical (NLO)single crystals of sodium succinate hexahydrate (SSH) (β phase) has been grown by a slow evaporation growth technique using aqueous solution at ambient temperature. The lattice parameters and morphology of SSH were determined by single crystal X-ray diffraction analysis. SSH crystallizes in centrosymmetric monoclinic system with space group P 21 / c and the crystalline purity was analyzed by powder X-ray diffraction analysis. The UV-vis-NIR spectrum reveals that the crystal is transparent in the entire visible region. The recorded FT-IR spectrum verified the presence of various functional groups in the material. NMR analysis of the grown crystal confirms the structural elucidation and detects the major and minor functional groups present in the title compound. ICP-OES analysis proved the presence of sodium in SSH. TG-DTA/DSCanalysis was used to investigate the thermal stability of the material. The dielectric permittivity and dielectric loss of SSH were carried out as a function of frequency for different temperatures and the results were discussed. The mechanical stability was evaluated from Vicker's microhardness test. The third order nonlinear optical properties of SSH has been investigated employing Z-scan technique with He-Ne laser operating at 632.8 nm wavelength.

  8. 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.

  9. The growth of high density network of MOF nano-crystals across macroporous metal substrates - Solvothermal synthesis versus rapid thermal deposition

    Science.gov (United States)

    Maina, James W.; Gonzalo, Cristina Pozo; Merenda, Andrea; Kong, Lingxue; Schütz, Jürg A.; Dumée, Ludovic F.

    2018-01-01

    Fabrication of metal organic framework (MOF) films and membranes across macro-porous metal substrates is extremely challenging, due to the large pore sizes across the substrates, poor wettability, and the lack of sufficient reactive functional groups on the surface, which prevent high density nucleation of MOF crystals. Herein, macroporous stainless steel substrates (pore size 44 × 40 μm) are functionalized with amine functional groups, and the growth of ZIF-8 crystals investigated through both solvothermal synthesis and rapid thermal deposition (RTD), to assess the role of synthesis routes in the resultant membranes microstructure, and subsequently their performance. Although a high density of well interconnected MOF crystals was observed across the modified substrates following both techniques, RTD was found to be a much more efficient route, yielding high quality membranes under 1 h, as opposed to the 24 h required for solvothermal synthesis. The RTD membranes also exhibited high gas permeance, with He permeance of up to 2.954 ± 0.119 × 10-6 mol m-2 s-1 Pa-1, and Knudsen selectivities for He/N2, Ar/N2 and CO2/N2, suggesting the membranes were almost defect free. This work opens up route for efficient fabrication of MOF films and membranes across macro-porous metal supports, with potential application in electrically mediated separation applications.

  10. 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.

  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. Studies on the growth aspects, structural, thermal, dielectric and third order nonlinear optical properties of solution grown 4-methylpyridinium p-nitrophenolate single crystal

    Science.gov (United States)

    Devi, S. Reena; Kalaiyarasi, S.; Zahid, I. MD.; Kumar, R. Mohan

    2016-11-01

    An ionic organic optical crystal of 4-methylpyridinium p-nitrophenolate was grown from methanol by slow evaporation method at ambient temperature. Powder and single crystal X-ray diffraction studies revealed the crystal system and its crystalline perfection. The rocking curve recorded from HRXRD study confirmed the crystal quality. FTIR spectral analysis confirmed the functional groups present in the title compound. UV-visible spectral study revealed the optical window and band gap of grown crystal. The thermal, electrical and surface laser damage threshold properties of harvested crystal were examined by using TGA/DTA, LCR/Impedance Analyzer and Nd:YAG laser system respectively. The third order nonlinear optical property of grown crystal was elucidated by Z-scan technique.

  13. 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

  14. 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.

  15. Synthesis, growth, structural, optical and thermal properties of a new organic nonlinear optical crystal: 2-amino 5-chloropyridinium-L-tartarate

    Science.gov (United States)

    Jayanalina, T.; Rajarajan, G.; Boopathi, K.; Sreevani, K.

    2015-09-01

    A new organic nonlinear optical crystal 2-amino-5-chloropyridinium-L-tartarate [2A5CPLTA] has been synthesized and the crystals were grown by slow evaporation solution technique at room temperature using methanol as solvent. The crystal structure of the title compound has been determined by the single crystal X-ray diffraction study and it belongs to the monoclinic system with noncentrosymmetric space group P21. The presence of functional groups was ascertained by Fourier transform infrared analysis. The transmittance and lower cut off of the grown crystal was ascertained by the UV-vis-NIR spectroscopy. Thermal studies reveled that 2A5CPLTA crystal is thermally stable up to 144 °C. The dielectric measurements of the grown crystal were carried out with different frequencies and temperatures. Vickers micro hardness measurement was carried out to study the mechanical behavior of the grown crystal. The second harmonic generation of the title crystal was confirmed by the Kurtz-Perry powder test employing the Nd: YAG laser as the source.

  16. 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

  17. Thermal expansion accompanying the glass-liquid transition and crystallization

    Directory of Open Access Journals (Sweden)

    M. Q. Jiang

    2015-12-01

    Full Text Available We report the linear thermal expansion behaviors of a Zr-based (Vitreloy 1 bulk metallic glass in its as-cast, annealed and crystallized states. Accompanying the glass-liquid transition, the as-cast Vitreloy 1 shows a continuous decrease in the thermal expansivity, whereas the annealed glass shows a sudden increase. The crystallized Vitreloy 1 exhibits an almost unchanged thermal expansivity prior to its melting. Furthermore, it is demonstrated that the nucleation of crystalline phases can induce a significant thermal shrinkage of the supercooled liquid, but with the growth of these nuclei, the thermal expansion again dominates. These results are explained in the framework of the potential energy landscape, advocating that the configurational and vibrational contributions to the thermal expansion of the glass depend on both, structure and temperature.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Growth, spectral, thermal, laser damage threshold, microhardness, dielectric, linear and nonlinear optical properties of an organic single crystal: L-phenylalanine DL-mandelic acid

    Energy Technology Data Exchange (ETDEWEB)

    Jayaprakash, P. [PG & Research Department of Physics, Arignar Anna Govt. Arts College, Cheyyar 604 407, Tamil Nadu (India); Peer Mohamed, M. [PG & Research Department of Physics, Arignar Anna Govt. Arts College, Cheyyar 604 407, Tamil Nadu (India); Department of Physics, C. Abdul Hakeem College, Melvisharam 632 509, Tamil Nadu (India); Krishnan, P. [Department of Physics, St. Joseph’s College of Engineering, Chennai 600 119, Tamil Nadu (India); Nageshwari, M.; Mani, G. [PG & Research Department of Physics, Arignar Anna Govt. Arts College, Cheyyar 604 407, Tamil Nadu (India); Lydia Caroline, M., E-mail: lydiacaroline2006@yahoo.co.in [PG & Research Department of Physics, Arignar Anna Govt. Arts College, Cheyyar 604 407, Tamil Nadu (India)

    2016-12-15

    Single crystals of L-phenylalanine dl-mandelic acid [C{sub 9}H{sub 11}NO{sub 2}. C{sub 8}H{sub 8}O{sub 3}], have been grown by the slow evaporation technique at room temperature using aqueous solution. The single crystal XRD study confirms monoclinic system for the grown crystal. The functional groups present in the grown crystal have been identified by FTIR and FT-Raman analyses. The optical absorption studies show that the crystal is transparent in the visible region with a lower cut-off wavelength of 257 nm and the optical band gap energy E{sub g} is determined to be 4.62 eV. The Kurtz powder second harmonic generation was confirmed using Nd:YAG laser with fundamental wavelength of 1064 nm. Further, the thermal studies confirmed no weight loss up to 150°C for the as-grown crystal. The photoluminescence spectrum exhibited three peaks (414 nm, 519 nm, 568 nm) due to the donation of protons from carboxylic acid to amino group. Laser damage threshold value was found to be 4.98 GW/cm{sup 2}. The Vickers microhardness test was carried out on the grown crystals and there by Vickers hardness number (H{sub v}), work hardening coefficient (n), yield strength (σ{sub y}), stiffness constant C{sub 11} were evaluated. The dielectric behavior of the crystal has been determined in the frequency range 50 Hz–5 MHz at various temperatures.

  3. Crystal growth, structural, spectral, thermal, dielectric, linear and nonlinear optical characteristics of a new organic acentric material: L-Methionine-Succinic acid (2/1)

    Science.gov (United States)

    Nageshwari, M.; Kumari, C. Rathika Thaya; Vinitha, G.; Mohamed, M. Peer; Sudha, S.; Caroline, M. Lydia

    2018-03-01

    L-Methionine-Succinic acid (2/1) (LMSA), 2C5H11NO2S·C4H6O4, a novel nonlinear optical material which belongs to the class of organic category was grown-up for the first time by the technique of slow evaporation. Purity of LMSA was improved using repetitive recrystallization. LMSA was analyzed by single crystal and powder X-ray diffraction investigation to affirm the crystal structure and crystalline character. The single crystal XRD revealed that LMSA corresponds to the crystal system of triclinic with P1 as space group showing the asymmetric unit consists of a neutral succinic acid molecule and two methionine residues which are crystallographically independent existing in zwitterionic form. The functional groups existing in LMSA was accomplished using Fourier transform infrared spectroscopy. The optical transparency and the band gap energy were identified utilizing UV-Visible spectrum. The optical constants specifically reflectance and extinction coefficient clearly indicate the elevated transparency of LMSA. The thermal analyses affirmed its thermal stability. The luminescence behavior of LMSA has been analyzed by Photoluminescence (PL) spectral study. The mechanical, laser damage threshold and dielectric investigation of LMSA was done to suggest the material for practical applications. The second and third harmonic generation efficacy was confirmed by means of Kurtz-Perry and Z-scan procedure which attest its potentiality in the domain of nonlinear optics.

  4. Thermal diode made by nematic liquid crystal

    Energy Technology Data Exchange (ETDEWEB)

    Melo, Djair, E-mail: djfmelo@gmail.com [Instituto de Física, Universidade Federal de Alagoas, Av. Lourival Melo Mota, s/n, 57072-900 Maceió, AL (Brazil); Fernandes, Ivna [Instituto de Física, Universidade Federal de Alagoas, Av. Lourival Melo Mota, s/n, 57072-900 Maceió, AL (Brazil); Moraes, Fernando [Departamento de Física, CCEN, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900, João Pessoa, PB (Brazil); Departamento de Física, Universidade Federal Rural de Pernambuco, 52171-900 Recife, PE (Brazil); Fumeron, Sébastien [Institut Jean Lamour, Université de Lorraine, BP 239, Boulevard des Aiguillettes, 54506 Vandoeuvre les Nancy (France); Pereira, Erms [Escola Politécnica de Pernambuco, Universidade de Pernambuco, Rua Benfíca, 455, Madalena, 50720-001 Recife, PE (Brazil)

    2016-09-07

    This work investigates how a thermal diode can be designed from a nematic liquid crystal confined inside a cylindrical capillary. In the case of homeotropic anchoring, a defect structure called escaped radial disclination arises. The asymmetry of such structure causes thermal rectification rates up to 3.5% at room temperature, comparable to thermal diodes made from carbon nanotubes. Sensitivity of the system with respect to the heat power supply, the geometry of the capillary tube and the molecular anchoring angle is also discussed. - Highlights: • An escaped radial disclination as a thermal diode made by a nematic liquid crystal. • Rectifying effects comparable to those caused by carbon and boron nitride nanotubes. • Thermal rectification increasing with radius and decreasing with height of the tube. • Asymmetric BCs cause rectification from the spatial asymmetry produced by the escape. • Symmetric BCs provide rectifications smaller than those yields by asymmetric BCs.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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)

  10. Growth, thermal properties and laser operation of a novel disordered Yb:Ca3La2(BO3)4 laser crystal

    Science.gov (United States)

    Pan, Zhongben; Cai, Huaqiang; Huang, Hui; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2014-10-01

    A high quality disordered Yb:Ca3La2(BO3)4 laser crystal has been successfully grown by the Czochralski method. The complete set of anisotropic thermal properties were systematically measured for the first time. In addition, continuous-wave laser along the three crystallographic axis were obtained. Passively Q-switched by a Cr4+:YAG saturable absorber, the laser yielded an average output power of 0.47 W with a slope efficiency of 7.6% for the first time. The generated pulse energy, duration, and peak power were 94 μJ, 33 ns, and 2.85 KW, respectively. We believe that the reliability and stability of these lasers makes the disordered Yb:Ca3La2(BO3)4 crystal of considerable interest for future applications.

  11. Synthesis, crystal structure, thermal analysis and dielectric

    Indian Academy of Sciences (India)

    Annual Meetings · Mid Year Meetings · Discussion Meetings · Public Lectures · Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 39; Issue 5. Synthesis, crystal structure, thermal analysis and dielectric properties of two mixed trichlorocadmiates (II).

  12. 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.

  13. 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)

  14. Measurements of thermal conductivity and thermal diffusivity of hen egg-white lysozyme crystals using a short hot wire method

    Science.gov (United States)

    Fujiwara, Seiji; Maki, Syou; Tanaka, Seiichi; Maekawa, Ryunosuke; Masuda, Tomoki; Hagiwara, Masayuki

    2017-07-01

    Thermal conductivity and thermal diffusivity of hen egg-white lysozyme (HEWL) crystals were examined by using the transient short hot wire method. This method is based on the conventional hot wire method, but improved by using a wire that is much shorter than conventional ones. The magneto-Archimedes levitation technique was utilized to attach the HEWL crystals onto the wire. Owing to the upward magnetic force, the HEWL crystals were deposited at the air-liquid interface of the protein buffer solution where the short hot wire was preliminarily fixed. In situ observation clarified that the wire was completely buried into the HEWL crystals. By means of these techniques, the measurement of thermal conductivity and thermal diffusivity of HEWL crystals was realized for the first time. Gadolinium chloride (a paramagnetic subject) was used as a precipitant agent of crystallization. Crystal growth was carried out over 20 h at 17.2 °C. The applied magnetic field was 4 T. Measurements were conducted during the crystal growth at two different times. The thermal conductivity and diffusivity of the HEWL crystals were determined to be 0.410 W/(m.K) and 3.77×10-8 m2/s at 14 h after, and 0.438 W/(m.K) and 5.18×10-8 m2/s at 20 h after, respectively. We emphasize that this method is versatile and applicable for other protein crystals.

  15. 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

  16. A new ~1 μm laser crystal Nd:Gd2SrAl2O7: growth, thermal, spectral and lasing properties

    Science.gov (United States)

    Yuan, Feifei; Liao, Wenbin; Huang, Yisheng; Zhang, Lizhen; Sun, Shijia; Wang, Yeqing; Lin, Zhoubin; Wang, Guofu; Zhang, Ge

    2018-03-01

    Nd:Gd2SrAl2O7 crystals were grown by the Czochralski technique; thermal, spectral and laser properties were investigated in detail. The average thermal expansion coefficients along a- and c-axis are 12.6  ×  10-6 K-1 and 14.9  ×  10-6 K-1, respectively. At room temperature, the thermal conductivities are 4.98 and 5.24 W (m-1 * K-1) along the a- and c-axis, respectively. The absorption cross sections at ~808 nm are 13.7  ×  10-20 cm2 with a FWHM of 3.3 nm for π-polarization and 11.84  ×  10-20 cm2 with a FWHM of 3.4 nm for σ-polarization. The emission cross sections at ~1080 nm are 15  ×  10-20 cm2 and 12.7  ×  10-20 cm2 with a FWHM of about 5.1 nm and 12.5 nm for π- and σ-polarization, respectively. The fluorescence lifetime for the 4F3/2  →  4I11/2 transition was fitted to be 118 µs. Pumped by a fiber-coupled 808 nm laser diode, the maximum 1.55 W continuous-wave laser output at ~1.08 µm was achieved with a slope efficiency of 30.5%. All the results show that Nd:Gd2SrAl2O7 crystal is a promising laser material.

  17. Single-crystal growth, crystallography, magnetic susceptibility, heat capacity, and thermal expansion of the antiferromagnetic S=1 chain compound CaV[subscript 2]O[subscript 4

    Energy Technology Data Exchange (ETDEWEB)

    Niazi, A.; Bud' ko, S.L.; Schlagel, D.L.; Yan, J.Q.; Lograsso, T.A.; Kreyssig, A.; Das, S.; Nandi, S.; Goldman, A.I.; Honecker, A.; McCallum, R.W.; Reehuis, M.; Pieper, O.; Lake, B.; Johnston, D.C.; (Ames; Gö); (tingen); (HMI); (MXPL-F)

    2009-05-01

    The compound CaV{sub 2}O{sub 4} contains V{sup +3} cations with spin S=1 and has an orthorhombic structure at room temperature containing zigzag chains of V atoms running along the c axis. We have grown single crystals of CaV{sub 2}O{sub 4} and report crystallography, static magnetization, magnetic susceptibility x, ac magnetic susceptibility, heat capacity C{sub p}, and thermal expansion measurements in the temperature T range of 1.8--350 K on the single crystals and on polycrystalline samples. An orthorhombic-to-monoclinic structural distortion and a long-range antiferromagnetic (AF) transition were found at sample-dependent temperatures T{sub S}{approx}108--145 K and T{sub N}{approx}51--76 K, respectively. In two annealed single crystals, another transition was found at {approx}200 K. In one of the crystals, this transition is mostly due to V{sub 2}O{sub 3} impurity phase that grows coherently in the crystals during annealing. However, in the other crystal the origin of this transition at 200 K is unknown. The x(T) shows a broad maximum at {approx}300 K associated with short-range AF ordering and the anisotropy of x above T{sub N} is small. The anisotropic x(T{yields}0) data below T{sub N} show that the (average) easy axis of the AF magnetic structure is the b axis. The C{sub p}(T) data indicate strong short-range AF ordering above T{sub N}, consistent with the x(T) data. We fitted our x data by a J{sub 1}-J{sub 2} S=1 Heisenberg chain model, where J{sub 1}(J{sub 2}) is the (next)-nearest-neighbor exchange interaction. We find J{sub 1}{approx}230 K and surprisingly, J{sub 2}/J{sub 1}{approx}0 (or J{sub 1}/J{sub 2}{approx}0). The interaction J{sub {perpendicular}} between these S=1 chains leading to long-range AF ordering at T{sub N} is estimated to be J{sub {perpendicular}}/J{sub 1}{approx_equal}0.04.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. Synthesis, crystal growth, thermal studies and scaled quantum chemical studies of structural and vibrational spectra of the highly efficient organic NLO crystal: 1-(4-Aminophenyl)-3-(3,4-dimethoxyphenyl)-prop-2-en-1-one

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Lynnette [Department of Physics, Bishop Moore College, Mavelikara, Alappuzha 690110, Kerala (India); Department of Physics, C.M.S College, Kottayam 686001, Kerala (India); Sajan, D., E-mail: dsajand@gmail.com [Department of Physics, Bishop Moore College, Mavelikara, Alappuzha 690110, Kerala (India); Shettigar, Venkataraya [Department of Physics, Gokhale Centenary College, Ankola 581 314, Karnataka (India); Chaitanya, K. [Key Laboratory of Soft Chemistry and Functional Materials of MOE, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Misra, Neeraj [Department of Physics, University of Lucknow, Lucknow 22607 (India); Sundius, Tom [Department of Physics, University of Helsinki, P.O. Box 64, FIN-00014 Helsinki (Finland); Němec, I. [Charles University in Prague, Faculty of Science, Department of Inorganic Chemistry, Hlavova 8, 128 40 Prague 2 (Czech Republic)

    2013-08-15

    A new chalcone derivative, 1-(4-aminophenyl)-3-(3,4-dimethoxyphenyl)-prop-2-en-1-one (DMAC) was synthesized and single crystals were grown by slow evaporation technique. The FT-Raman and FT-IR spectra of the sample were recorded in the region 3700–100 cm{sup −1} and 4000–400 cm{sup −1}, respectively. The spectra were interpreted with the aid of normal coordinate analysis following structure optimizations and force field calculations based on density functional theory (DFT) at the B3LYP/6-311+G(d,p) level of theory. Normal coordinate calculations were performed using the DFT force field, corrected by a recommended set of scaling factors, yielding fairly good agreement between the observed and calculated wavenumbers. DMAC is thermally stable up to 220.0 °C and optically transparent in the visible region. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with electrostatic potential surfaces (ESP). The SHG efficiency of DMAC is observed to be 10 times that of standard urea crystal of identical particle size. - Highlights: • A chalcone derivative, DMAC has been synthesized and crystals are grown. • FT-IR and FT-Raman spectra, thermogravimetric and UV–Vis studies were carried out. • SHG effect from a centrosymmetric crystal has been reported.

  6. 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)

  7. 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.

  8. 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

  9. Non-isothermal crystallization kinetics and thermal behaviour of ...

    Indian Academy of Sciences (India)

    Administrator

    neering applications. The thermal property and crystalli- zation behaviour of these blends greatly influence the polymer properties through the crystal structure and mor- phology generated. Hence, it is desirable to study the thermal behaviour and crystallization kinetics of. PA/elastomer blends in both the isothermal and non-.

  10. 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

  11. Thermal behaviour of strontium tartrate single crystals grown in gel

    Indian Academy of Sciences (India)

    Thermal behaviour of strontium tartrate crystals grown with the aid of sodium metasilicate gel is investigated using thermogravimetry (TG) and differential thermal analysis (DTA). Effect of magnetic field and dopant (Pb)2+ on the crystal stability is also studied using thermal analysis. This study reveals that water molecules are ...

  12. 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.

  13. 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.

  14. Crystal growth and evaluation of scintillation properties of Eu and alkali-metal co-doped LiSrAlF{sub 6} single crystals for thermal neutron detector

    Energy Technology Data Exchange (ETDEWEB)

    Wakahara, Shingo; Yokota, Yuui; Yamaji, Akihiro; Fujimoto, Yutaka; Sugiyama, Makoto; Kurosawa, Shunsuke [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe), 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Pejchal, Jan [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Institute of Physics AS CR, Cukrovarnicka 10, Prague 16253 (Czech Republic); Kawaguchi, Noriaki [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Tokuyama, Co. Ltd., Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); Fukuda, Kentaro [Tokuyama, Co. Ltd., Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (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)

    2012-12-15

    In recent work, Na co-doping have found to improve the light output of Eu doped LiCaAlF{sub 6} (Eu:LiCAF) for thermal neutron scintillator. We grew Eu 2% and alkali metal 1% co-doped LiSAF crystals by Micro-Pulling down method to understand the effect of alkali metal co-doping on scintillation properties and mechanism compared with LiCAF. In photo- and {alpha}-ray induced radio-luminescence spectra of the all grown crystals, the emissions from d-f transition of Eu{sup 2+} were observed. Without relation to excitation source, decay times of co-doped LiSAF were longer than Eu only doped one. The light yield of Na, K and Cs co-doped LiSAF under {sup 252}Cf neutron excitation were improved. Especially, K co-doped Eu:LiSAF reached 33200 ph/n, which outperformed Eu only doped one by approximately 20% (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. 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

  16. 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

  17. 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

  18. 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)

  19. 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.

  20. 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.

  1. Application of liquid crystals in thermal nondestructive evaluation

    International Nuclear Information System (INIS)

    Panakal, J.P.; Mukherjee, S.; Ghosh, J.K.

    1983-01-01

    In recent years, thermal nondestructive evaluation using Cholestric liquid crystals have found wide applications in industry. Thermography using Cholesteric liquid crystals can be used for detection of nonbonds in metallic composites, hot spots in electronic circuits and preliminary examination of welded pressure vessels. This paper presents the results of experiments on thermography of components using encapsulated liquid crystals. (author)

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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 ...

  7. Mold Flux Crystallization and Mold Thermal Behavior

    Science.gov (United States)

    Peterson, Elizabeth Irene

    Mold flux plays a small but critical role in the continuous casting of steel. The carbon-coated powder is added at the top of the water-cooled copper mold, over time it melts and infiltrates the gap between the copper mold and the solidifying steel strand. Mold powders serve five primary functions: (1) chemical insulation, (2) thermal insulation, (3) lubrication between the steel strand and mold, (4) absorption of inclusions, and (5) promotion of even heat flux. All five functions are critical to slab casting, but surface defect prevention is primarily controlled through even heat flux. Glassy fluxes have high heat transfer and result in a thicker steel shell. Steels with large volumetric shrinkage on cooling must have a crystalline flux to reduce the radiative heat transfer and avoid the formation of cracks in the shell. Crystallinity plays a critical role in steel shell formation, therefore it is important to study the thermal conditions that promote each phase and its morphology. Laboratory tests were performed to generate continuous cooling transformation (CCT) and time-temperature-transformation (TTT) diagrams. Continuous cooling transformation tests were performed in an instrumented eight cell step chill mold. Results showed that cuspidine was the only phase formed in conventional fluxes and all observed structures were dendritic. An isothermal tin bath quench method was also developed to isothermally age glassy samples. Isothermal tests yielded different microstructures and different phases than those observed by continuous cooling. Comparison of aged tests with industrial flux films indicates similar faceted structures along the mold wall, suggesting that mold flux first solidifies as a glass along the mold wall, but the elevated temperature devitrifies the glassy structure forming crystals that cannot form by continuous cooling.

  8. 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...

  9. 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.)

  10. 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.

  11. (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.

  12. Peculiarities of linear thermal expansion of CuInS2 single crystal

    International Nuclear Information System (INIS)

    Akira, Nagaoka; Kenji, Yoshino; Hideto, Miyake

    2010-01-01

    Full text : I-III-VI 2 chalcopyrire semiconductors have made rapid progress in recent years. In addition chalcopyrite semiconductors show unique thermal properties. Usually, liner thermal expansion in semiconductors increases with increasing temperature. However, liner thermal expansion of most chalcopyrite semiconductors decreases at low temperature. For example, AgGaSe 2 shows decreasing the liner thermal expansion below 100 K 1 , 2). It is well known that high-quality single crystals of the I-III-VI 2 compounds are difficult to grow because most of the compounds grow through a peritectic reaction or a solid state transition during the cooling process. CuInS 2 single crystal can be grown by traveling heater method (THM), which is one of the solution growth techniques. Advantages of the THM growth are following that growth temperature is low compared with that of the other melt growth and larger crystals can be grown compared with a conventional solution growth. In a previous study, CuGaS 2 , CuGaSe 2 , CuGaTe 2 , CuInSe 2 ternary compounds have been obtained by the THM technique. In this work, it is investigated a liner thermal expansion of single crystal CuInS 2 by using X-ray diffraction. Measurement temperature was changed from 10 K to 300 K. From results of XRD measurement, it is calculated lattice constants of a and c axes and the liner thermal expansion. As a result, lattice constants of a axis increase with increasing temperature, that of c axis decreases with increasing temperature. The liner thermal expansion decreases for T 2 single crystal at low temperature

  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. Effect of power history on the shape and the thermal stress of a large sapphire crystal during the Kyropoulos process

    Science.gov (United States)

    Nguyen, Tran Phu; Chuang, Hsiao-Tsun; Chen, Jyh-Chen; Hu, Chieh

    2018-02-01

    In this study, the effect of the power history on the shape of a sapphire crystal and the thermal stress during the Kyropoulos process are numerically investigated. The simulation results show that the thermal stress is strongly dependent on the power history. The thermal stress distributions in the crystal for all growth stages produced with different power histories are also studied. The results show that high von Mises stress regions are found close to the seed of the crystal, the highly curved crystal surface and the crystal-melt interface. The maximum thermal stress, which occurs at the crystal-melt interface, increases significantly in value as the crystal expands at the crown. After this, there is reduction in the maximum thermal stress as the crystal lengthens. There is a remarkable enhancement in the maximum von Mises stress when the crystal-melt interface is close to the bottom of the crucible. There are two obvious peaks in the maximum Von Mises stress, at the end of the crown stage and in the final stage, when cracking defects can form. To alleviate this problem, different power histories are considered in order to optimize the process to produce the lowest thermal stress in the crystal. The optimal power history is found to produce a significant reduction in the thermal stress in the crown stage.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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)

  1. 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.

  2. Remarkable reduction of thermal conductivity in phosphorene phononic crystal.

    Science.gov (United States)

    Xu, Wen; Zhang, Gang

    2016-05-05

    Phosphorene has received much attention due to its interesting physical and chemical properties, and its potential applications such as thermoelectricity. In thermoelectric applications, low thermal conductivity is essential for achieving a high figure of merit. In this work, we propose to reduce the thermal conductivity of phosphorene by adopting the phononic crystal structure, phosphorene nanomesh. With equilibrium molecular dynamics simulations, we find that the thermal conductivity is remarkably reduced in the phononic crystal. Our analysis shows that the reduction is due to the depressed phonon group velocities induced by Brillouin zone folding, and the reduced phonon lifetimes in the phononic crystal. Interestingly, it is found that the anisotropy ratio of thermal conductivity could be tuned by the 'non-square' pores in the phononic crystal, as the phonon group velocities in the direction with larger projection of pores is more severely suppressed, leading to greater reduction of thermal conductivity in this direction. Our work provides deep insight into thermal transport in phononic crystals and proposes a new strategy to reduce the thermal conductivity of monolayer phosphorene.

  3. 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.

  4. Effect of oxalic acid on the optical, thermal, dielectric and mechanical behaviour of ADP crystals

    International Nuclear Information System (INIS)

    Rajesh, P.; Ramasamy, P.

    2009-01-01

    The effect of the addition, over a concentration range from 1 to 5 mol%, of oxalic acid on the growth rate, optical transparency, hardness, dielectric behaviour, and SHG efficiency of ammonium dihydrogen phosphate single crystals grown by slow evaporation method has been investigated. UV-Vis studies show that the transparency of the oxalic acid added crystals decreased gradually. Thermal studies indicate that the decomposition temperatures of the crystal are decreased in oxalic acid added ADP crystals. It is observed from the dielectric measurements that the dielectric constant and dielectric loss increase with increase in temperature for all the crystals. Vicker's microhardness study reveals that the addition of higher concentration of oxalic acid decreases the hardness of the crystal. SHG efficiency of 1 mol% of oxalic acid is higher than the pure ADP.

  5. Synthesis, crystal structure, thermal analysis and dielectric ...

    Indian Academy of Sciences (India)

    In both the materials, the crystal structure has been determined by X-ray single crystal analysis at room temperature (293 K). The compound structures consist of K + (or NH 4 + ) cations and double chains of CdCl 6 octahedra sharing one edge extending along b -axis. The mixture of KA + /NH 4 + cations are located ...

  6. imide, crystal structure, thermal and dielectric studies

    Indian Academy of Sciences (India)

    Abstract. A new geminal di-cationic ionic liquid (IL) containing a central cationic unit methylidene capped by a basic functionality (imidazole) is synthesized. The compound was characterized by means of 1H, 13C, 19F NMR,. IR and Raman spectroscopies and its crystal structure is confirmed by single crystal X-ray diffraction ...

  7. Thermal expansion of crystals of the N2 type

    International Nuclear Information System (INIS)

    Tolkachev, A.M.; Manzhelii, V.G.; Azarenkov, V.P.; Jezowski, A.; Kosobutskaya, E.A.

    1981-01-01

    Linear expansion coefficients of low temperature crystals with linear molecules and Pa3 lattice N 2 (2-21 K), CO(2-28 K), CO 2 (2-25 K), N 2 O(2-90 K) were measured. A version of the law of corresponding states to describe the translational component of the thermal expansion of the substances studied and other low temperature crystals with close-packed lattices is proposed. In the thermal properties of crystals consisting of molecules without inversion centre, we have found anomalies interpreted as the evidence of a partial dipole ordering. (orig.)

  8. 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 ...

  9. 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 ...

  10. 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.

  11. 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.)

  12. 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.

  13. Thermal conductivity of niobium single crystals in a magnetic field

    International Nuclear Information System (INIS)

    Gladun, C.; Vinzelberg, H.

    1980-01-01

    The thermal conductivity in longitudinal magnetic fields up to 5 T and in the temperature range 3.5 to 15 K is measured in two high purity niobium single crystals having residual resistivity ratios of 22700 and 19200 and orientations of the rod axis [110] and [100]. The investigations show that by means of the longitudinal magnetic field the thermal conductivity may decrease only to a limiting value. In the crystal directions [110] and [100] for the ratio of the thermal conductivity in zero field and the thermal conductivity in the saturation field the temperature-independent factors 1.92 and 1.27, respectively, are determined. With the aid of these factors the thermal conductivity in the normal state is evaluated from the measured values of thermal conductivity below Tsub(c) in the magnetic field. The different conduction and scattering mechanisms are discussed. (author)

  14. Thermal neutron detectors based on complex oxide crystals

    CERN Document Server

    Ryzhikov, V; Volkov, V; Chernikov, V; Zelenskaya, O

    2002-01-01

    The ways of improvement of spectrometric quality of CWO and GSO crystals have been investigated with the aim of their application in thermal neutron detectors based on radiation capture reactions. The efficiency of the neutron detection by these crystals was measured, and the obtained data were compared with the results for sup 6 LiI(Tl) crystals. It is shown that the use of complex oxide crystals and neutron-absorption filters for spectrometry of thermal and resonance neutrons could be a promising method in combination with computer data processing. Numerical calculations are reported for spectra of gamma-quanta due to radiation capture of the neutrons. To compensate for the gamma-background lines, we used a crystal pair of heavy complex oxides with different sensitivity to neutrons.

  15. Analysis of the temperature dependence of the thermal conductivity of insulating single crystal oxides

    Directory of Open Access Journals (Sweden)

    E. Langenberg

    2016-10-01

    Full Text Available The temperature dependence of the thermal conductivity of 27 different single crystal oxides is reported from ≈20 K to 350 K. These crystals have been selected among the most common substrates for growing epitaxial thin-film oxides, spanning over a range of lattice parameters from ≈3.7 Å to ≈12.5 Å. Different contributions to the phonon relaxation time are discussed on the basis of the Debye model. This work provides a database for the selection of appropriate substrates for thin-film growth according to their desired thermal properties, for applications in which heat management is important.

  16. 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.

  17. 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.

  18. Thermal Conductivity and Liquid Crystal Thermometers.

    Science.gov (United States)

    Edge, R. D., Ed.

    1993-01-01

    Describes using stock liquid crystal postcards as inexpensive classroom thermometers. Also suggests using these postcards as a good visual temperature indicator for classroom demonstrations such as temperature gradients. One such activity is provided. (MVL)

  19. 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.

  20. Synthesis, crystal structure, thermal analysis and dielectric ...

    Indian Academy of Sciences (India)

    2.2 X-ray structure determination. Two transparent parallelepipedic crystals with dimensions,. 0.20 × 0.12 × 0.04 and 0.26 × 0.14 × 0.12, were chosen from the preparation. The intensity data were collected on. An APEX II diffractometer with graphite–crystal monochro- mated MoKα radiation (0.71073 Å). Lorentz and polariz-.

  1. 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.

  2. 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.

  3. 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

  4. 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)

  5. Review of aragonite and calcite crystal morphogenesis in thermal spring systems

    Science.gov (United States)

    Jones, Brian

    2017-06-01

    Aragonite and calcite crystals are the fundamental building blocks of calcareous thermal spring deposits. The diverse array of crystal morphologies found in these deposits, which includes monocrystals, mesocrystals, skeletal crystals, dendrites, and spherulites, are commonly precipitated under far-from-equilibrium conditions. Such crystals form through both abiotic and biotic processes. Many crystals develop through non-classical crystal growth models that involve the arrangement of nanocrystals in a precisely controlled crystallographic register. Calcite crystal morphogenesis has commonly been linked to a ;driving force;, which is a conceptual measure of the distance of the growth conditions from equilibrium conditions. Essentially, this scheme indicates that increasing levels of supersaturation and various other parameters that produce a progressive change from monocrystals and mesocrystals to skeletal crystals to crystallographic and non-crystallographic dendrites, to dumbbells, to spherulites. Despite the vast amount of information available from laboratory experiments and natural spring systems, the precise factors that control the driving force are open to debate. The fact that calcite crystal morphogenesis is still poorly understood is largely a reflection of the complexity of the factors that influence aragonite and calcite precipitation. Available information indicates that variations in calcite crystal morphogenesis can be attributed to physical and chemical parameters of the parent water, the presence of impurities, the addition of organic or inorganic additives to the water, the rate of crystal growth, and/or the presence of microbes and their associated biofilms. The problems in trying to relate crystal morphogenesis to specific environmental parameters arise because it is generally impossible to disentangle the controlling factor(s) from the vast array of potential parameters that may act alone or in unison with each other.

  6. 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

  7. 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-.

  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. Vibrational and Thermal Properties of Oxyanionic Crystals

    Science.gov (United States)

    Korabel'nikov, D. V.

    2018-03-01

    The vibrational and thermal properties of dolomite and alkali chlorates and perchlorates were studied in the gradient approximation of density functional theory using the method of a linear combination of atomic orbitals (LCAO). Long-wave vibration frequencies, IR and Raman spectra, and mode Gruneisen parameters were calculated. Equation-of-state parameters, thermodynamic potentials, entropy, heat capacity, and thermal expansion coefficient were also determined. The thermal expansion coefficient of dolomite was established to be much lower than for chlorates and perchlorates. The temperature dependence of the heat capacity at T > 200 K was shown to be generally governed by intramolecular vibrations.

  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. 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. Synthesis, crystal structure, thermal analysis and dielectric ...

    Indian Academy of Sciences (India)

    [13] Perry C H and Lowdes R P 1969 J. Chem. Phys. 51 3648. [14] Sheldrick G M 1997 SHELXS9, Program for the Refinement of Crystal Structures (Germany: University of Gottingen). [15] Loukil M, Kabadou A, Salles Ph and Ben Salah A 2004 Chem. Phys. 300 247. [16] Rolies M M and De Ranter C J 1978 Acta Crystallogr.

  16. Crystal structure, thermal behavior, vibrational spectroscopy and ...

    Indian Academy of Sciences (India)

    64

    SHELXL-97 programs included in WINGX package [6, 7, and 8]. ... Elmer software. 2.6. Absorption and photoluminescence measurements. A PerkinElmer LS 55 spectrometer and exciting with 350 nm radiation were used to record ..... [8] Farrugia LJ, 1999, WinGX suite for small-molecule single-crystal crystallography. J.of.

  17. Crystal structure and thermal property of polyethylene glycol octadecyl ether

    International Nuclear Information System (INIS)

    Meng, Jie-yun; Tang, Xiao-fen; Li, Wei; Shi, Hai-feng; Zhang, Xing-xiang

    2013-01-01

    Highlights: ► The crystal structure of C18En for n ≥ 20 is a monoclinic system. ► Polyethylene glycol octadecyl ether crystallizes perfectly. ► The number of repeat units has significant effect on the melting, crystallizing temperature and enthalpy. ► The thermal stable temperature increases rapidly with increasing the number of repeat unit. - Abstract: The crystal structure, phase change property and thermal stable temperature (T d ) of polyethylene glycol octadecyl ether [HO(CH 2 CH 2 O) n C 18 H 37 , C18En] with various numbers of repeat units (n = 2, 10, 20 and 100) as phase change materials (PCMs) were investigated using temperature variable Fourier transformed infrared spectroscopy (FTIR), wide-angle X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TG). C18En crystallizes perfectly at 0 °C; and the crystal structure for n ≥ 20 is a monoclinic system. The number of repeat units has great effect on the phase change properties of C18En. The thermal stable temperature increases rapidly with increasing the number of repeat units. They approach to that of PEG-2000 as the number of repeat units is more than 10. T d increases rapidly with increasing the number of repeat units. C18En are a series of promising polymeric PCMs

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Intrinsic thermal expansion of crystal defects

    International Nuclear Information System (INIS)

    Ganne, J.-P.

    1981-02-01

    Although the phenomenon of thermal expansion has long been known, the intrinsic thermal expansion coefficient (ITEC) βsub(d) of a point defect, derived from its formation volume vsub(d), has never been measured directly. The differential dilatometer by interferometry built by ASTY and GILDER is described. It has allowed βsub(d) to be measured for several defects. Vacancies and small interstitial loops were produced in aluminium by low temperature (20 K) fast neutron irradiation followed by an anneal up to the beginning of stage III (160 K). The very high value of the measured ratio βsub(d)/β 0 (12+-4) is comparable with a lattice statics calculated (42) value (11.5 0 [fr

  4. Synthesis and Spectroscopic, Thermal and Crystal Structure Studies ...

    African Journals Online (AJOL)

    NICO

    The salt undergoes melting followed by decomposition to give gaseous products. KEYWORDS. Hydrazine, succinic acid, hydrazinium hydrogensuccinate, crystal structure, thermal studies. 1. Introduction. Dibasic acids are known to form N2H5HA, (N2H5)2A and. N2H5HA.H2A type salts (H2A = dibasic acid) with hydrazine.

  5. Thermal, optical and spectroscopic characterizations of borate laser crystals

    Czech Academy of Sciences Publication Activity Database

    Chavoutier, M.; Jubera, V.; Veber, P.; Velazquez, M.; Viraphong, O.; Hejtmánek, Jiří; Decourt, R.; Debray, J.; Menaert, B.; Segonds, P.; Adamietz, F.; Rodriguez, V.; Manek-Hönninger, I.; Fargues, A.; Descamps, D.; Garcia, A.

    2011-01-01

    Roč. 184, č. 2 (2011), s. 441-446 ISSN 0022-4596 Institutional research plan: CEZ:AV0Z10100521 Keywords : borate crystals * thermal properties * refractive index * luminescence * ytterbium * laser materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.159, year: 2011

  6. Extra phase noise from thermal fluctuations in nonlinear optical crystals

    DEFF Research Database (Denmark)

    César, J. E. S.; Coelho, A.S.; Cassemiro, K.N.

    2009-01-01

    We show theoretically and experimentally that scattered light by thermal phonons inside a second-order nonlinear crystal is the source of additional phase noise observed in optical parametric oscillators. This additional phase noise reduces the quantum correlations and has hitherto hindered the d...

  7. 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.

  8. Effect of defects induced by doping and fast neutron irradiation on the thermal properties of lithium ammonium sulphate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kandil, S.H.; Ramadan, T.A.; Darwish, M.M. (Alexandria Univ. (Egypt). Dept. of Materials Science); Kassem, M.E.; El-Khatib, A.M. (Alexandria Univ. (Egypt). Dept. of Physics)

    1994-05-01

    Structural defects were introduced in lithium ammonium sulphate crystals (LAS) either in the process of crystal growth (in the form of foreign ions) or by neutron irradiation. The effect of such defects on the thermal properties of LAS crystals was studied in the temperature range 300-500 K. It was assumed that the doped LAS crystals are composed of a two-phase system having different thermal parameters in each phase. The specific heat at constant pressure, C[sub p], of irradiated samples was found to decrease with increasing irradiation doses. The thermal expansion of LAS crystals was found to be dependent on neutron irradiation, and was attributed to two processes: the release of new species and the trapping process. (author).

  9. Ultrafast crystallization and thermal stability of In-Ge doped eutectic Sb70Te30 phase change material

    International Nuclear Information System (INIS)

    Lee Meiling; Miao Xiangshui; Ting Leehou; Shi Luping

    2008-01-01

    Effect of In and Ge doping in the form of In 2 Ge 8 Sb 85 Te 5 on optical and thermal properties of eutectic Sb 70 Te 30 alloys was investigated. Crystalline structure of In 2 Ge 8 Sb 85 Te 5 phase change material consists of a mixture of phases. Thermal analysis shows higher crystallization temperature and activation energy for crystallization. Isothermal reflectivity-time measurement shows a growth-dominated crystallization mechanism. Ultrafast crystallization speed of 30 ns is realized upon irradiation by blue laser beam. The use of ultrafast and thermally stable In 2 Ge 8 Sb 85 Te 5 phase change material as mask layer in aperture-type super-resolution near-field phase change disk is realized to increase the carrier-to-noise ratio and thermal stability

  10. 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.

  11. Anisotropic thermal transport in phosphorene: effects of crystal orientation.

    Science.gov (United States)

    Liu, Te-Huan; Chang, Chien-Cheng

    2015-06-28

    As an intrinsic thermally anisotropic material, the thermal properties of phosphorene must vary with respect to the crystal chirality. Nevertheless, previous studies of heat transfer in phosphorene have been limited to the 0.0° (zigzag, ZZ) and 90.0° (armchair, AC) chiralities. In this study, we investigate the orientation-dependent thermal transport in phosphorene sheets with a complete set of crystal chirality ranging from 0.0° to 90.0° using the Boltzmann transport equation (BTE) associated with the first-principles calculations. It was found that in the phosphorene sheets, the intrinsic thermal conductivity is a smooth monotonic decreasing function of the crystal chirality, which exhibits sinusoidal behavior bounded by the two terminated values 48.9 (0.0°) and 27.8 (90.0°) W m(-1) K(-1). The optical modes have unusually large contributions to heat transfer, which account for almost 30% of the total thermal conductivity of phosphorene sheets. This is because the optical phonons have comparable group velocities and relaxation times to the acoustic phonons.

  12. 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.)

  13. 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

  14. 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.

  15. 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%.

  16. Crystal growth, structural, spectral, thermal, linear and nonlinear optical characterization of a new organic nonlinear chiral compound: L-tryptophan-fumaric acid-water (1/1/1) suitable for laser frequency conversion

    Science.gov (United States)

    Peer Mohamed, M.; Jayaprakash, P.; Nageshwari, M.; Rathika Thaya Kumari, C.; Sangeetha, P.; Sudha, S.; Mani, G.; Lydia Caroline, M.

    2017-08-01

    A new organic active nonlinear optical crystal L-tryptophan fumaric acid water (1/1/1), (C15H17N2 O7. H2O)(LTFAW), consisting of zwitterion tryptophan molecule in conjunction with a fumaric acid molecule and a water molecule was grown by slow solvent evaporation technique from aqueous solution. The organic chromophore crystallizes from water in its zwitterions exhibiting tabular habit in monoclinic system with acentric space group C2 (Z = 4). The sharp peaks observed in Powder X-ray diffractogram depicts the crystalline nature. The presence of functional groups in the grown crystal was analyzed using FT-IR spectrum. The carbon and hydrogen environment in molecular structure was investigated using FT-NMR technique using deuterated DMSO solution. Ultraviolet-visible spectral analysis reveal that the crystal possess lower cut-off wavelength down to 275 nm, is a key factor to exhibit Second Harmonic Generation (SHG) signal. The direct optical band gap is evaluated to be 5.28 eV from the UV absorption profile. The evaluation of optical constants by employing UV-visible absorbance data such as, extinction coefficient, reflectance, refractive index, optical conductivity are supportive towards good performance as NLO devices. Temperature of decomposition was investigated using thermogravimetric analysis/differential thermal analysis techniques (TG/DTA). The luminescence profile exhibited two peaks (362 nm, 683 nm) due to the donation of protons from carboxylic group to amino group. The nonlinear optical behavior from the noncentrosymmetric crystal was observed by the generation of frequency doubled (2ω) optical radiation when subjected to pulsed Nd:YAG laser (1064 nm, 10 ns, 10 Hz) using Kurtz-Perry method. The variation of dielectric constant (εʹ) and dielectric loss (εʹʹ) vs. Log f for the title compound was analysed at a few selected temperatures and frequencies.

  17. High dno/dT liquid crystals and their applications in a thermally tunable liquid crystal photonic crystal fiber

    DEFF Research Database (Denmark)

    Li, J.; Gauza, S.; Wu, S.-T.

    2006-01-01

    We have analyzed the physical origins of the temperature gradient of the ordinary refractive index (odn/dT) of liquid crystals. To achieve a large odn/dT , high birefringence (Delta n) and low clearing temperature play crucial roles. Based on these guidelines, we formulated two exemplary liquid...... crystal mixtures, designated as UCF-1 and UCF-2. The dn(o)/dT of UCF-1 is similar to 4x higher than that of 5CB at room temperature. By infiltrating UCF-1 into the air holes of a three-rod core photonic crystal fiber, we demonstrate a thermally tunable photonic bandgap fiber with tuning sensitivity of 27...

  18. 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

  19. 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.

  20. 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.

  1. Process of making cryogenically cooled high thermal performance crystal optics

    Science.gov (United States)

    Kuzay, T.M.

    1992-06-23

    A method is disclosed for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N[sub 2] is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation. 7 figs.

  2. Crystallization and thermal properties of Polylactide/Palygorskite composites

    CSIR Research Space (South Africa)

    Kesavan Pillai, Sreejarani

    2014-06-01

    Full Text Available of Applied Polymer Science For Peer Review 1 Crystallization and thermal properties of polylactide/palygorskite composites Sreejarani Kesavan Pillai1*, Vincent Ojijo1 and Suprakas Sinha Ray1,2,3 1DST/CSIR Nanotechnology Innovation Centre, National... limits the processability of the polymer.3 This specifically becomes an issue when PLA is to be used in extrusion and injection moulding where it is hard to get high PLA crystallinity in a short time.4 Therefore, how to enhance crystallization kinetics...

  3. Thermal and electrical transport properties of ? single crystals

    Science.gov (United States)

    Gamal, G. A.; Nassary, M. M.; Nagat, A. T.; Abou-Alwafa, A. M.

    1996-04-01

    Electrical conductivity, Hall effect and thermoelectric power measurements are made for the compound 0268-1242/11/4/009/img2. This compound, which is a semiconductor grown in a single-crystal form, is studied over a wide range of temperature from 150 to 375 K. The crystal is grown by a modification of the Bridgman method. The combination of the electrical and thermal measurements in the present investigation makes it possible to find various physical parameters and to reveal the general behaviour of this semiconductor.

  4. Modification of Thermal Emission via Metallic Photonic Crystals

    International Nuclear Information System (INIS)

    Norris, David J.; Stein, Andreas; George, Steven M.

    2012-01-01

    Photonic crystals are materials that are periodically structured on an optical length scale. It was previously demonstrated that the glow, or thermal emission, of tungsten photonic crystals that have a specific structure - known as the 'woodpile structure' - could be modified to reduce the amount of infrared radiation from the material. This ability has implications for improving the efficiency of thermal emission sources and for thermophotovoltaic devices. The study of this effect had been limited because the fabrication of metallic woodpile structures had previously required a complex fabrication process. In this project we pursued several approaches to simplify the fabrication of metallic photonic crystals that are useful for modification of thermal emission. First, we used the self-assembly of micrometer-scale spheres into colloidal crystals known as synthetic opals. These opals can then be infiltrated with a metal and the spheres removed to obtain a structure, known as an inverse opal, in which a three-dimensional array of bubbles is embedded in a film. Second, we used direct laser writing, in which the focus of an infrared laser is moved through a thin film of photoresist to form lines by multiphoton polymerization. Proper layering of such lines can lead to a scaffold with the woodpile structure, which can be coated with a refractory metal. Third, we explored a completely new approach to modified thermal emission - thin metal foils that contain a simple periodic surface pattern, as shown in Fig. 1. When such a foil is heated, surface plasmons are excited that propagate along the metal interface. If these waves strike the pattern, they can be converted into thermal emission with specific properties.

  5. Thermal characterization of nanoscale phononic crystals using supercell lattice dynamics

    Directory of Open Access Journals (Sweden)

    Bruce L. Davis

    2011-12-01

    Full Text Available The concept of a phononic crystal can in principle be realized at the nanoscale whenever the conditions for coherent phonon transport exist. Under such conditions, the dispersion characteristics of both the constitutive material lattice (defined by a primitive cell and the phononic crystal lattice (defined by a supercell contribute to the value of the thermal conductivity. It is therefore necessary in this emerging class of phononic materials to treat the lattice dynamics at both periodicity levels. Here we demonstrate the utility of using supercell lattice dynamics to investigate the thermal transport behavior of three-dimensional nanoscale phononic crystals formed from silicon and cubic voids of vacuum. The periodicity of the voids follows a simple cubic arrangement with a lattice constant that is around an order of magnitude larger than that of the bulk crystalline silicon primitive cell. We consider an atomic-scale supercell which incorporates all the details of the silicon atomic locations and the void geometry. For this supercell, we compute the phonon band structure and subsequently predict the thermal conductivity following the Callaway-Holland model. Our findings dictate that for an analysis based on supercell lattice dynamics to be representative of the properties of the underlying lattice model, a minimum supercell size is needed along with a minimum wave vector sampling resolution. Below these minimum values, a thermal conductivity prediction of a bulk material based on a supercell will not adequately recover the value obtained based on a primitive cell. Furthermore, our results show that for the relatively small voids and void spacings we consider (where boundary scattering is dominant, dispersion at the phononic crystal unit cell level plays a noticeable role in determining the thermal conductivity.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Thermal conductivity of bulk GaN single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Jezowski, A.; Stachowiak, P.; Suski, T.; Krukowski, S.; Bockowski, M.; Grzegory, I.; Danilchenko, B

    2003-05-01

    We have measured thermal conductivity, {kappa}, in the wide temperature range 4-300 K of GaN bulk single crystals grown by high-pressure, high-temperature synthesis. Obtained results (1600 W/Km at 45 K) are the highest {kappa} values reported on GaN material. At the room temperature {kappa} is about 210 W/Km. The contributions to the GaN thermal resistance of Umklapp process, mass point defects as well as phonon scattering on dislocations and sample boundary are discussed.

  12. 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)

  13. Lattice variation and thermal parameters of gel grown KDP crystals ...

    Indian Academy of Sciences (India)

    Pure and impurity added (with NH4Cl, NH4NO3, NH4H2PO4, and (NH4)2SO4) KDP single crystals were grown by the gel method using silica gels. X-ray diffraction data were collected for powder samples and used for the estimation of lattice variation and thermal parameters like Debye–Waller factor, mean-square ...

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. (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.

  20. 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.)

  1. 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....

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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%.

  9. Thermal analysis of line-defect photonic crystal lasers

    DEFF Research Database (Denmark)

    Xue, Weiqi; Ottaviano, Luisa; Chen, Yaohui

    2015-01-01

    under CW optical pumping, whereas InGaAsP membranes only lase under pulsed conditions. By varying the duty cycle of the pump beam, we quantify the heating induced by optical pumping in the two material platforms and compare their thermal properties. Full 3D finite element simulations show the spatial......We report a systematic study of thermal effects in photonic crystal membrane lasers based on line-defect cavities. Two material platforms, InGaAsP and InP, are investigated experimentally and numerically. Lasers with quantum dot layers embedded in an InP membrane exhibit lasing at room temperature...... temperature profile and are in good agreement with the experimental results concerning the thermal tolerance of the two platforms....

  10. 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.

  11. Synthesis, linear optical, non-linear optical, thermal and mechanical characterizations of dye-doped semi-organic NLO crystals

    International Nuclear Information System (INIS)

    Sesha Bamini, N; Choedak, Tenzin; Muthukrishnan, P; Ancy, C J; Vidyalakshmy, Y; Kejalakshmy, N

    2015-01-01

    Organic laser dyes Coumarin 485, Coumarin 540 and Rhodamine 590 Chloride were used to dope potassium acid phthalate crystals (KAP). Dye-doped KAP crystals with different dye concentrations such as 0.01 mM, 0.03 mM, 0.05 mM, 0.07 mM and 0.09 mM (in the KAP growth solution) were grown. The linear optical, non-linear optical, mechanical and thermal characterizations of dye-doped KAP crystals were studied and compared to understand the effect of dye and dye concentration on the KAP crystal. Absorption and emission studies of KAP and dye-doped KAP single crystals indicated the inclusion of the dye into the KAP crystal lattice. The effect of dye and its concentration on the SHG efficiency of the KAP crystal was studied using the Kurtz and Perry powder technique. It was observed that the absorption maximum wavelength and concentration of the dye used for doping the KAP single crystal decided the SHG efficiency of the dye-doped KAP single crystals. The mechanical hardness of the dye-doped and undoped (pure) KAP single crystals were studied using the Vickner’s microhardness test. It was observed that doping the KAP crystals with the laser dyes changed them from softer material to harder material. Etching studies showed an improvement in the optical quality of the KAP crystal after doping with laser dyes. (paper)

  12. 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

  13. 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

  14. 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)

  15. 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

  16. Thermal decomposition kinetics of strontium permanganate trihydrate, cadmium permanganate hexahydrate and calcium permanganate pentahydrate crystals

    International Nuclear Information System (INIS)

    Sakurai, K.R.; Schaeffer, D.A.; Herley, P.J.

    1978-01-01

    A thermogravimetric study of the kinetics of thermal nuclei formation and growth has been carried out for the dehydration and decomposition of single crystal strontium permanganate trihydrate, cadmium permanganate hexahydrate, and calcium permanganate pentahydrate. The isothermal dehydration of strontium parmanganate trihydrate occurs in two stages between 50 and 100 0 C. The dehydration kinetics suggest that the two dehydration stages are based on a single-step nucleation process followed by a growth process without nuclei overlap. The resulting activation energies are consistent with the proposed nucleation theory. For the dehydration kinetics of cadmium permanganate hexahydrate, an overlapping nucleation growth mechanism appears to be operating between 30 and 60 0 C. The results are irreproducible for the dehydration of calcium permanganate pentahydrate at 100 0 C. The thermal decomposition studies indicate that the data of the sigmoidal, isothermal fractional decomposition vs. time curves are reproducible for whole and ground crystals of each dehydrated permanganate. All of the data plots contain an induction or slow rate period, an acceleratory and a decay period. The induction period can be shortened by irradiation with 60 Co γ-rays prior to decomposition. Activation energies obtained for all three materials for the various thermal decomposition periods are found to be similar to those published previously on other alkali and alkaline-earth permanganates. (Auth.)

  17. 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.

  18. 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 ...

  19. 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 ...

  20. 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.

  1. 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.

  2. 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)

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. Method for thermal processing alumina-enriched spinel single crystals

    Science.gov (United States)

    Jantzen, Carol M.

    1995-01-01

    A process for age-hardening alumina-rich magnesium aluminum spinel to obtain the desired combination of characteristics of hardness, clarity, flexural strength and toughness comprises selection of the time-temperature pair for isothermal heating followed by quenching. The time-temperature pair is selected from the region wherein the precipitate groups have the characteristics sought. The single crystal spinel is isothermally heated and will, if heated long enough pass from its single phase through two pre-precipitates and two metastable precipitates to a stable secondary phase precipitate within the spinel matrix. Quenching is done slowly at first to avoid thermal shock, then rapidly.

  10. Local lattice dynamics and negative thermal expansion in crystals

    Energy Technology Data Exchange (ETDEWEB)

    Fornasini, P [Dip. di Fisica, Universita di Trento, Via Sommarive 14, I-38050 Povo (Trento) (Italy); Sanson, A [Ist. di Fotonica e Nanotecnologie del CNR, Sezione di Trento, I-38050 Povo (Trento) (Italy); Vaccari, M [European Synchrotron Radiation Facility, Grenoble (France); Artioli, G [Dip. di Geoscienze, University di Padova, via Giotto 1, I-35137 Padova (Italy); Dapiaggi, M [Dip. di Scienze della Terra, Universita di Milano, via Botticelli 23, I-20133 Milan (Italy)

    2007-12-15

    The investigations on the origin of negative thermal expansion (NTE) in crystals can greatly benefit from the joint use of Bragg diffraction and extended x-ray absorption fine structure (EXAFS). In this paper, the relative merits of the two techniques are critically discussed, and recent results on CuCl (zincblende structure) and Cu{sub 2}O and Ag{sub 2}O (cuprite structure) are compared. The tension effect giving rise to NTE can be correlated to the anisotropy of the mean square relative displacements.

  11. 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 ...

  12. 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

  13. 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

  14. 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.

  15. 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 ...

  16. Grain growth and thermal stability accompanying recrystallization in undercooled Ni-3at.%Sn alloy

    International Nuclear Information System (INIS)

    Chen, Z.; Chen, Q.; Shen, C.J.; Liu, F.

    2015-01-01

    The grain growth and thermal stability after recrystallization in as-solidified highly undercooled Ni-3at.%Sn alloy melt were investigated. As for undercooled Ni-3at.%Sn alloy, a transition from dendritic to granular crystals occurred when ΔT≥ΔT * , which was induced by the plastic deformation of dendrites and subsequent recrystallization. On this basis, the subsequent grain growth and solute segregation accompanying recalescence were calculated by a recently proposed thermo-kinetic model, which showed close agreement with the experimental results. It is concluded that the grain growth process was interrelated to recalescence, solute trapping and solute segregation of Sn atoms captured by solute trapping, which was responsible for the reduction of grain boundary energy and improvement of thermal stability. - Highlights: • A transition from dendritic to granular crystals occurred when ΔT≥ΔT * . • The grain growth accompanying recalescence was calculated. • A close agreement with the experimental results was shown

  17. 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

  18. Stochastic modeling of thermal fatigue crack growth

    CERN Document Server

    Radu, Vasile

    2015-01-01

    The book describes a systematic stochastic modeling approach for assessing thermal-fatigue crack-growth in mixing tees, based on the power spectral density of temperature fluctuation at the inner pipe surface. It shows the development of a frequency-temperature response function in the framework of single-input, single-output (SISO) methodology from random noise/signal theory under sinusoidal input. The frequency response of stress intensity factor (SIF) is obtained by a polynomial fitting procedure of thermal stress profiles at various instants of time. The method, which takes into account the variability of material properties, and has been implemented in a real-world application, estimates the probabilities of failure by considering a limit state function and Monte Carlo analysis, which are based on the proposed stochastic model. Written in a comprehensive and accessible style, this book presents a new and effective method for assessing thermal fatigue crack, and it is intended as a concise and practice-or...

  19. Crystallization of nuclear glass under a thermal gradient: application to the self-crucible produced in the skull melting process

    International Nuclear Information System (INIS)

    Delattre, O.

    2013-01-01

    In the context of the vitrification of high level nuclear waste, a new industrial process has been launched in 2010 at the La Hague factory: The skull melting process. This setup applies thermal gradients to the melt, which leads to the formation of a solid layer of glass: the 'self-crucible'. The question would be to know whether these thermal gradients have an impact or not on the crystallization behaviour of the considered glasses in the self crucible. In order to answer that question, the crystallization of two glass compositions of nuclear interest has been investigated with an image analysis based method in isothermal and thermal gradient heat treatments conditions. The isothermal experiments allow for the quantification (growth speed, nucleation, crystallized fraction) of the crystallization of apatites (660 C-900 C) and powellites (630 C-900 C). The comparison of the results obtained through these two types of experimentations allows us to conclude that there is no impact of the thermal gradient on the crystallization of the studied glass compositions. In order to complete the image analysis study (based on surfaces), in and ex situ microtomography experiments have been performed at ESRF (Grenoble) on the ID19 beamline. This study allowed us to follow the crystallization of apatites in a simplified glass and to confirm the reliability of the image analysis method based on the analysis of surfaces. (author) [fr

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. The opto-thermal effect on encapsulated cholesteric liquid crystals

    Science.gov (United States)

    Liu, Yu-Sung; Lin, Hui-Chi; Yang, Kin-Min

    2017-12-01

    In this study, we implemented a micro-encapsulated CLC electronic paper that is optically addressed and electrically erasable. The mechanism that forms spot diameters on the CLC films is discussed and verified through various experimental parameters, including the thickness of CLCs and Poly(2,3-dihydrothieno-1,4-dioxin)-poly(styrenesulfonate) (PEDOT:PSS), pump intensity, and pumping time. The opto-thermal effect, brought on by the PEDOT:PSS absorbing layer, causes the spot diameters on the cholesteric liquid crystal thin films to vary. According to our results, the spot diameter is larger for a sample with a thinner cholesteric liquid crystal layer with the same excitation conditions and same thickness of the PEDOT layer. The spot diameter is also larger for a sample with a thicker PEDOT under the same excitation conditions and same thickness of the cholesteric liquid crystal layer. We proposed a simple heat-conducting model to explain the experimental results, which qualitatively agree with this theoretical model.

  10. Crystallization behaviour and thermal stability of two aluminium-based metallic glass powder materials

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.P.; Yan, M. [University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, QLD 4072 (Australia); Yang, B.J. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, J.Q., E-mail: jqwang@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Schaffer, G.B. [University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, QLD 4072 (Australia); Qian, M., E-mail: ma.qian@uq.edu.au [University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, QLD 4072 (Australia)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer The crystallization paths and products of Al{sub 86}Ni{sub 7}Y{sub 4.5}Co{sub 1}La{sub 1.5} powder have been identified. Black-Right-Pointing-Pointer The thermal stability of Al{sub 86}Ni{sub 7}Y{sub 4.5}Co{sub 1}La{sub 1.5} powder has been assessed. Black-Right-Pointing-Pointer The Al{sub 86}Ni{sub 7}Y{sub 4.5}Co{sub 1}La{sub 1.5} powder shows a wide processing window of 75 K. Black-Right-Pointing-Pointer The powder has the potential to be consolidated into thick BMG components based on the findings. Black-Right-Pointing-Pointer The Al{sub 85}Ni{sub 5}Y{sub 6}Co{sub 2}Fe{sub 2} powder shows similar characteristics but inferior thermal stability. - Abstract: The crystallization behaviour and thermal stability of two Al-based metallic glass powder materials, Al{sub 85}Ni{sub 5}Y{sub 6}Co{sub 2}Fe{sub 2} and Al{sub 86}Ni{sub 6}Y{sub 4.5}Co{sub 2}La{sub 1.5}, have been investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electron microscopy. Both alloy powders show a distinct three-stage crystallization process with a similar gap of {approx}75 K between the onset crystallization temperature (T{sub x}) and the second crystallization temperature. Crystallization occurs by the precipitation and growth of fcc-Al, without intermetallic formation. The apparent activation energy for each stage of crystallization was determined from DSC analyses and the phases resulting from each crystallization stage were identified by XRD and electron microscopy. The critical cooling rate for each alloy powder was calculated from the DSC data. These results are necessary to inform the consolidation of amorphous powder particles of Al{sub 85}Ni{sub 5}Y{sub 6}Co{sub 2}Fe{sub 2} or Al{sub 86}Ni{sub 6}Y{sub 4.5}Co{sub 2}La{sub 1.5} into thick (>1 mm) metallic glass components.

  11. 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.

  12. Structural, vibrational, thermal and optical studies of organic single crystal: Benzotriazolium p-toluene sulfonate (BTPTS)

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, R. Ramesh; Sathya, P.; Gopalakrishnan, R., E-mail: krgkrishnan@yahoo.com [Department of Physics, College of Engineering, Guindy, Anna University, Chennai-600 025 (India)

    2016-05-06

    Benzotriazolium p-toluene sulfonate (BTPTS) was grown by solution growth technique. The powder X-ray diffraction analysis was carried out to evaluate crystal system of the compound. LeBail Profile fitting analysis was performed to extract the individual peak intensities. FTIR spectrum analysis was recorded to study vibration frequencies of the prepared organic salt. Thermal studies were carried out using TG-DSC analysis. Optical absorption and energy band gap of the title compound was evaluated by UV-Vis spectral study.

  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. 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.

  17. Thermal gradient migration of brine inclusions in salt crystals

    International Nuclear Information System (INIS)

    Yagnik, S.K.

    1982-01-01

    Natural salt deposits, which are being considered for high-level nuclear wastes repositories, contain a small volume fraction of water in the form of brine inclusions distributed throughout the salt. Radioactive decay heating of the nuclear wastes will impose a temperature gradient on the surrounding salt which mobilizes the brine inclusions. Inclusions filled completely with brine (the all-liquid inclusions) migrate up the temperature gradient and eventually accumulate brine near the buried waste forms. The brine may slowly corrode or degrade the waste forms which is undesirable. In the present work, thermal gradient migration of both all-liquid and gas-liquid inclusions was experimentally studied in synthetic single crystals of NaCl and KCl using a hot-stage attachment to an optical microscope which was capable of imposing temperature gradients and axial compressive loads on the crystals. The migration velocities of the inclusions were found to be dependent on temperature, temperature gradient, and inclusion shape and size. The velocities were also dictated by the interfacial mass transfer resistance at brine/solid interface. This interfacial resistance depends on the dislocation density in the crystal, which in turn, depends on the axial compressive loading of the crystal. At low axial loads, the dependence between the velocity and temperature gradient is nonlinear. At high axial loads, however, the interfacial resistance is reduced and the migration velocity depends linearly on the temperature gradient. All-liquid inclusions filled with mixed brines were also studied. For gas-liquid inclusions, three different gas phases (helium, air and argon) were compared. Migration studies were also conducted on single crystallites of natural salt as well as in polycrystalline natural salt samples. The behavior of the inclusions at large angle grain boudaries was observed

  18. Thermal-gradient migration of brine inclusions in salt crystals

    International Nuclear Information System (INIS)

    Yagnik, S.K.

    1982-09-01

    It has been proposed that high-level nuclear waste be disposed in a geologic repository. Natural-salt deposits, which are being considered for this purpose, contain a small volume fraction of water in the form of brine inclusions distributed throughout the salt. Radioactive-decay heating of the nuclear wastes will impose a temperature gradient on the surrounding salt which mobilizes the brine inclusions. Inclusions filled completely with brine migrate up the temperature gradient and eventually accumulate brine near the buried waste forms. The brine may slowly corrode or degrade the waste forms which is undesirable. In this work, thermal gradient migration of both all-liquid and gas-liquid inclusions was experimentally studied in synthetic single crystals of NaCl and KCl using a hot-stage attachment to an optical microscope which was capable of imposing temperature gradients and axial compressive loads on the crystals. The migration velocities of the inclusions were found to be dependent on temperature, temperature gradient, and inclusion shape and size. The velocities were also dictated by the interfacial mass transfer resistance at brine/solid interface. This interfacial resistance depends on the dislocation density in the crystal, which in turn, depends on the axial compressive loading of the crystal. At low axial loads, the dependence between the velocity and temperature gradient is non-linear.At high axial loads, however, the interfacial resistance is reduced and the migration velocity depends linearly on the temperature gradient. All-liquid inclusions filled with mixed brines were also studied. For gas-liquid inclusions, three different gas phases (helium, air and argon) were compared. Migration studies were also conducted on single crystallites of natural salt as well as in polycrystalline natural salt samples. The behavior of the inclusions at large angle grain boundaries was observed. 35 figures, 3 tables

  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. The Effect of Thermal Cycling on Crystal-Liquid Separation During Lunar Magma Ocean Differentiation

    Science.gov (United States)

    Mills, Ryan D.

    2013-01-01

    Differentiation of magma oceans likely involves a mixture of fractional and equilibrium crystallization [1]. The existence of: 1) large volumes of anorthosite in the lunar highlands and 2) the incompatible- rich (KREEP) reservoir suggests that fractional crystallization may have dominated during differentiation of the Moon. For this to have occurred, crystal fractionation must have been remarkably efficient. Several authors [e.g. 2, 3] have hypothesized that equilibrium crystallization would have dominated early in differentiation of magma oceans because of crystal entrainment during turbulent convection. However, recent numerical modeling [4] suggests that crystal settling could have occurred throughout the entire solidification history of the lunar magma ocean if crystals were large and crystal fraction was low. These results indicate that the crystal size distribution could have played an important role in differentiation of the lunar magma ocean. Here, I suggest that thermal cycling from tidal heating during lunar magma ocean crystallization caused crystals to coarsen, leading to efficient crystal-liquid separation.

  1. 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.

  2. 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)

  3. 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%.

  4. 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

  5. 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.

  6. 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.

  7. 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 ...

  8. 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 ...

  9. Studies on crystal growth and physical properties of 4-(dimethylamino)benzaldehyde-2,4-dinitroaniline single crystal

    Science.gov (United States)

    Jebin, R. P.; Suthan, T.; Rajesh, N. P.; Vinitha, G.; Dhas, S. A. Britto

    2016-07-01

    The organic material 4-(dimethylamino)benzaldehyde-2,4-dinitroaniline has been grown by slow evaporation technique. Single crystal and Powder X-ray diffraction studies have been carried out to conform the grown crystal. FTIR and FT-Raman spectra were recorded to identify the functional groups present in the crystal. The optical property of the grown crystal was analysed by UV-Vis-NIR measurement. The thermal property of the grown crystal was analysed by thermogravimetric (TG) and differential thermal analyses (DTA). Thermal diffusivity of the grown crystal was analysed by Photo acoustic spectroscopic (PAS) studies. The third order nonlinear optical properties of 4-(dimethylamino)benzaldehyde-2,4-dinitroaniline was measured by the Z-scan technique using 532 nm diode pumped continuous wave (CW) Nd:YAG laser. The mechanical property of the grown crystal was analysed by using microhardness studies.

  10. 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.

  11. 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.

  12. 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

  13. 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.)

  14. Thermal profiles, crystallization behaviors and microstructure of diacylglycerol-enriched palm oil blends with diacylglycerol-enriched palm olein.

    Science.gov (United States)

    Xu, Yayuan; Zhao, Xiaoqing; Wang, Qiang; Peng, Zhen; Dong, Cao

    2016-07-01

    To elucidate the possible interaction mechanisms between DAG-enriched oils, this study investigated how mixtures of DAG-enriched palm-based oils influenced the phase behavior, thermal properties, crystallization behaviors and the microstructure in binary fat blends. DAG-enriched palm oil (PO-DAGE) was blended with DAG-enriched palm olein (POL-DAGE) in various percentages (0%, 10%, 30%, 50%, 70%, 90%, 100%). Based on the observation of iso-solid diagram and phase diagram, the binary mixture of PO-DAGE/POL-DAGE showed a better compatibility in comparison with their corresponding original blends. DSC thermal profiles exhibited that the melting and crystallization properties of PO-DAGE/POL-DAGE were distinctively different from corresponding original blends. Crystallization kinetics revealed that PO-DAGE/POL-DAGE blends displayed a rather high crystallization rate and exhibited no spherulitic crystal growth. From the results of polarized light micrographs, PO-DAGE/POL-DAGE blends showed more dense structure with very small needle-like crystals than PO/POL. X-ray diffraction evaluation revealed when POL-DAGE was added in high contents to PO-DAGE, above 30%, β-polymorph dominated, and the mount of β' forms crystals was decreasing. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Thermal expansion of C60 single crystals under pressure

    International Nuclear Information System (INIS)

    Grube, K.D.

    1995-12-01

    The thermal expansion and compressibility of C 60 single crystals have been investigated by a newly developed capacitive dilatometer. The dilatometer was integrated in a high pressure cell and exposed to a hydrostatic pressure of maximal 0.85 GPa with He or Ar as pressure transmitting medium. The relative length change of the C 60 -samples was measured with a resolution of ΔL/L∼10 -9 . The crystals consist of weakly bonded C 60 -molecules which can rotate nearly free at room temperature. The gradual freezing-in of the rotational motions leads to a first order phase transition at 260 K and a glass transition at 90 K. The pressure dependence of these transitions was determined in a temperature range from 50 K to 325 K up to a pressure of 0.85 GPa. The phase transition at 260 K shows a positive pressure dependence of 174 K/GPa. The glass transition temperature first increases with 75 K/GPa under pressure, then it jumps discontinuously by 10 K at 0.15 GPa followed by a further increase with a slope of 54 K/GPa. The jump in the glass transition temperature at 0.15 GPa can be explained with an orientation-dependent interaction between the C 60 -molecules. (orig.) [de

  16. 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.)

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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].

  5. 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 .

  6. 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

  7. 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.

  8. 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.

  9. Achieving dynamic behaviour and thermal expansion in the organic solid state via co-crystallization.

    Science.gov (United States)

    Hutchins, Kristin M; Groeneman, Ryan H; Reinheimer, Eric W; Swenson, Dale C; MacGillivray, Leonard R

    2015-08-01

    Thermal expansion involves a response of a material to an external stimulus that typically involves an increase in a crystallographic axis (positive thermal expansion (PTE)), although shrinking with applied heat (negative thermal expansion (NTE)) is known in rarer cases. Here, we demonstrate a means to achieve dynamic molecular motion and thermal expansions in organic solids via co-crystallizations. One co-crystal component is known to exhibit dynamic behaviour in the solid state while the second, when varied systematically, affords co-crystals with linear thermal expansion coefficients that range from colossal to nearly zero. Two co-crystals exhibit rare NTE. We expect the approach to guide the design of molecular solids that enable predesigned motion related to thermal expansion processes.

  10. 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.

  11. Structure and Growth Control of Organic–Inorganic Halide Perovskites for Optoelectronics: From Polycrystalline Films to Single Crystals

    Science.gov (United States)

    Chen, Yani; He, Minhong; Peng, Jiajun; Sun, Yong

    2016-01-01

    Recently, organic–inorganic halide perovskites have sparked tremendous research interest because of their ground‐breaking photovoltaic performance. The crystallization process and crystal shape of perovskites have striking impacts on their optoelectronic properties. Polycrystalline films and single crystals are two main forms of perovskites. Currently, perovskite thin films have been under intensive investigation while studies of perovskite single crystals are just in their infancy. This review article is concentrated upon the control of perovskite structures and growth, which are intimately correlated for improvements of not only solar cells but also light‐emitting diodes, lasers, and photodetectors. We begin with the survey of the film formation process of perovskites including deposition methods and morphological optimization avenues. Strategies such as the use of additives, thermal annealing, solvent annealing, atmospheric control, and solvent engineering have been successfully employed to yield high‐quality perovskite films. Next, we turn to summarize the shape evolution of perovskites single crystals from three‐dimensional large sized single crystals, two‐dimensional nanoplates, one‐dimensional nanowires, to zero‐dimensional quantum dots. Siginificant functions of perovskites single crystals are highlighted, which benefit fundamental studies of intrinsic photophysics. Then, the growth mechanisms of the previously mentioned perovskite crystals are unveiled. Lastly, perspectives for structure and growth control of perovskites are outlined towards high‐performance (opto)electronic devices. PMID:27812463

  12. Structure and Growth Control of Organic-Inorganic Halide Perovskites for Optoelectronics: From Polycrystalline Films to Single Crystals.

    Science.gov (United States)

    Chen, Yani; He, Minhong; Peng, Jiajun; Sun, Yong; Liang, Ziqi

    2016-04-01

    Recently, organic-inorganic halide perovskites have sparked tremendous research interest because of their ground-breaking photovoltaic performance. The crystallization process and crystal shape of perovskites have striking impacts on their optoelectronic properties. Polycrystalline films and single crystals are two main forms of perovskites. Currently, perovskite thin films have been under intensive investigation while studies of perovskite single crystals are just in their infancy. This review article is concentrated upon the control of perovskite structures and growth, which are intimately correlated for improvements of not only solar cells but also light-emitting diodes, lasers, and photodetectors. We begin with the survey of the film formation process of perovskites including deposition methods and morphological optimization avenues. Strategies such as the use of additives, thermal annealing, solvent annealing, atmospheric control, and solvent engineering have been successfully employed to yield high-quality perovskite films. Next, we turn to summarize the shape evolution of perovskites single crystals from three-dimensional large sized single crystals, two-dimensional nanoplates, one-dimensional nanowires, to zero-dimensional quantum dots. Siginificant functions of perovskites single crystals are highlighted, which benefit fundamental studies of intrinsic photophysics. Then, the growth mechanisms of the previously mentioned perovskite crystals are unveiled. Lastly, perspectives for structure and growth control of perovskites are outlined towards high-performance (opto)electronic devices.

  13. 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.

  14. 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.

  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. Crystal growth and characterization of semi-organic 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals for third-order nonlinear optical (NLO) applications

    Science.gov (United States)

    Vediyappan, Sivasubramani; Arumugam, Raja; Pichan, Karuppasamy; Kasthuri, Ramachandran; Muthu, Senthil Pandian; Perumal, Ramasamy

    2017-12-01

    Semi-organic nonlinear optical (NLO) 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals have been grown by slow evaporation solution technique (SEST) with the growth period of 60 days. The single-crystal XRD analysis confirms the unit cell parameters of the grown crystal. The crystallinity of grown 2A5NPBr was analyzed by powder X-ray diffraction (PXRD) measurement. The presence of functional groups of 2A5NPBr crystal was confirmed by Fourier transform infrared (FTIR) spectrum analysis. The optical transmittance of the grown crystal was analyzed by UV-Vis-NIR analysis. It shows good transparency in the visible and NIR region and it is favorable for nonlinear optical (NLO) device applications. The chemical etching study was carried out and it reveals that the grown crystal has less dislocation density. The photoconductivity study reveals that the grown crystal possesses positive photoconductive nature. The thermal stability of the crystal has been investigated by thermogravimetric (TG) and differential thermal analysis (DTA). The dielectric constant and dielectric loss as a function of frequency were measured. The electronic polarizability (α) of 2A5NPBr molecule has been calculated theoretically by different ways such as Penn analysis, Clausius-Mossotti relation, Lorentz-Lorenz equation, optical bandgap, and coupled dipole method (CDM). The obtained values of electronic polarizability (α) are in good agreement with each other. Laser damage threshold (LDT) of 2A5NPBr crystal has been measured using Nd:YAG laser with the wavelength of 1064 nm. Third-order nonlinear optical property of the grown crystal was studied by Z-scan technique using He-Ne laser of wavelength 632.8 nm.

  17. Polymorphic equilibrium responsive thermal and mechanical stimuli in light-emitting crystals of N-methylaminonaphthyridine.

    Science.gov (United States)

    Harada, Naomi; Abe, Yuichiro; Karasawa, Satoru; Koga, Noboru

    2012-12-21

    Crystal polymorphs of 1,8-naphthyridine derivative, being anti and syn conformers, show a reversible transformation from anti to syn by heating and from syn to anti by grinding with the alteration of emittance intensity, and notably, thermal transformation from anti to syn conformer took place in single-crystal-to-single-crystal (SC-to-SC) form, which was confirmed by a single crystal X-ray crystallography.

  18. Thermal neutron spectra measurements in IEAR-1 Reactor, by using a crystal spectrometer

    International Nuclear Information System (INIS)

    Fulfaro, R.; Figueiredo Neto, A.M.; Stasiulevicius, E.; Vinhas, L.A.

    1975-01-01

    The thermal neutron spectrum of the IEN Argonauta reactor has been measured in the wavelength from 0.7 to 1.9A, using a neutron crystal spectrometer. An aluminium single crystal, in transmission, was used as monochromator. The aluminium crystal reflectivity employed in the analysis of the data was calculated for the first five permitted orders. An effective absorption coefficient of the crystal was used to perform the calculations instead of the macroscopic cross section of the element

  19. A numerical simulation to verify the stress-free growth of silicon crystal ribbon

    Science.gov (United States)

    Ray, Sujit K.; Utku, Senol; Wada, Ben K.

    1987-01-01

    Thermal stresses developed during the growth of silicon crystal ribbon have been shown to be negligible, thus eliminating residual stresses and dislocations, if the temperature profile satisfies a second-order partial differential equation inside the ribbon. This has been numerically verified through a finite element model, an outline of which is presented here. This model shows that, for homogeneous isotropic material with temperature independent thermal expansion coefficients, thermal stresses will vanish if the temperature profile satisfies the Laplacian. A comparison of stresses due to uniform and nonuniform temperature gradients in the plane of the ribbon is also presented. The strategies employed to control the round-off error and to validate the computer model are discussed.

  20. Experimental determination of phonon thermal conductivity and Lorenz ratio of single crystal bismuth telluride

    OpenAIRE

    Yao, Mengliang; Wilson, Stephen; Zebarjadi, Mona; Opeil, Cyril

    2017-01-01

    We use a magnetothermal resistance method to measure the lattice thermal conductivity of a single crystal of Bi$_2$Te$_3$ from 5 to 60 K. We apply a large transverse magnetic field to suppress the electronic thermal conduction while measuring thermal conductivity and electrical resistivity. The lattice thermal conductivity is then calculated by extrapolating the thermal conductivity versus electrical conductivity curve to a zero electrical conductivity value. Our results show that the measure...

  1. 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.

  2. Growth and characterization of Tm-doped Y 2O 3 single crystals

    Science.gov (United States)

    Mun, J. H.; Jouini, A.; Novoselov, A.; Guyot, Y.; Yoshikawa, A.; Ohta, H.; Shibata, H.; Waseda, Y.; Boulon, G.; Fukuda, T.

    2007-07-01

    The rare-earth sesquioxides (RE2O3, RE = Lu, Y and Sc) are promising host materials for solid-state lasers due to their low phonon energy and high thermal conductivity. On the other hand, Tm3+ and Yb3+ are preferable activators for advanced laser diode pumped solid-state lasers. In addition to that, Tm-doped materials can be used for eye-safe lasers application. Tm-doped Y2O3 single crystals were grown using the micro-pulling-down method. Crystals were transparent with gray and blue colors of 4.2 mm in diameter and 13-20 mm in length. The crystallinity was characterized using X-ray rocking curve analysis. Tm-doped Y2O3 single crystals have a good compositional homogeneity along the growth axis and their thermal conductivity was calculated from the measurements of thermal diffusivity, heat capacity and density. We have also recorded absorption, fluorescence spectra and measured fluorescence lifetimes as a function of the Tm content, we have found a very attractive fluorescence around the eye-safe wavelength of 1.9 mm which corresponds to a 3F4 → 3H6 transition of Tm3+.

  3. 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].

  4. 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.

  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. 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.

  7. 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

  8. Synthesis, crystal structure, spectral and thermal properties of 4-dimethylaminopyridinium salicylate monohydrate

    Science.gov (United States)

    Arunkumar, A.; Ramasamy, P.

    2013-06-01

    4-dimethylaminopyridinium salicylate monohydrate (DMAPSA) was synthesized and its crystal structure was determined using single crystal X-ray diffraction analysis. From the crystal structure analysis it can be inferred that the crystal belongs to monoclinic system with space group of P21/n. Investigation has been carried out to assign the vibrational frequencies of the grown crystals by FTIR spectral studies. 1H and 13C FT-NMR has been recorded to elucidate the molecular structure. The molecular mass of DMAPSA has been measured using mass spectroscopic analysis. The thermal stability and thermal decomposition of DMAPSA have been investigated by means of thermogravimetric analysis and differential thermal analysis. The melting point of crystal was observed as 172 °C by melting point apparatus. Fluorescence spectra were taken for the excitation wavelength of 240 nm.

  9. 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

  10. 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.

  11. Tuning of a cavity in a silicon photonic crystal by thermal expansion of an elastomeric infill

    NARCIS (Netherlands)

    Erdamar, A.K.; Van Leest, M.M.; Picken, S.J.; Caro, J.

    2011-01-01

    We use an elastomer as infill material for a photonic crystal. As a result of the thermal-expansion-induced strongly negative thermal optical coefficient, this material is highly suitable for thermal tuning of the transmission of a cavity. This is demonstrated by global infilling of a hole-type

  12. Spectral, mechanical, thermal, optical and solid state parameters, of metal-organic bis(hydrogenmaleate)-CO(II) tetrahydrate crystal

    Energy Technology Data Exchange (ETDEWEB)

    Chandran, Senthilkumar [Centre for Crystal Growth, Department of Physics, SSN College of Engineering, Kalavakkam 603110 (India); Jagan, R. [Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India); Paulraj, Rajesh, E-mail: rajeshp@ssn.edu.in [Centre for Crystal Growth, Department of Physics, SSN College of Engineering, Kalavakkam 603110 (India); Ramasamy, P. [Centre for Crystal Growth, Department of Physics, SSN College of Engineering, Kalavakkam 603110 (India)

    2015-10-15

    Metal-organic bis(hydrogenmaleate)-Co(II) tetrahydrate single crystals have been grown by slow evaporation solution growth technique at room temperature. The crystal structure and the unit cell parameters were analyzed from the X-ray diffraction studies. Single-crystal X-ray diffraction analyses reveal that the grown crystal belongs to triclinic system with the space group P-1. Functional groups in bis(hydrogenmaleate)-Co(II) tetrahydrate were identified by Fourier transform infrared spectral analysis. The peak observed at 663 cm{sup −1} is assigned to the (Co–O) stretching vibrations. The optical transmission of the crystal was studied by UV–vis–NIR spectral analysis. The photoluminescence emission studies were carried out for the title compound in a wide wavelength range between 350 nm and 550 nm at 303 K. Mechanical strength was tested by Vickers microhardness test. The laser damage threshold value has been determined using Nd:YAG laser operating at 1064 nm. At various frequencies and temperatures the dielectric behavior of the material was investigated. Solid state parameters such as plasma energy, Penn gap, Fermi energy and electronic polarizability were evaluated. Photoconductivity measurements were carried out for the grown crystal in the presence of DC electric field at room temperature. Thermal stability and decomposition of the crystal were studied by TG–DTA. The weight loss of the title compound occurs in different steps. - Graphical abstract: Molecular structure of the bis(hydrogenmaleate)-Co(II) tetrahydrate drawn at 40% ellipsoid probability level. - Highlights: • Bis(hydrogenmaleate)-Co(II) tetrahydrate single crystal is grown by slow evaporation method. • Structural and optical properties were discussed. • The title complex crystal is thermally stable up to 91 °C. • Plasma energy, Fermi energy and electronic polarizability are evaluated. • It exhibits positive photoconductivity.

  13. 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

  14. 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

  15. Thermal stress resistance of ion implanted sapphire crystals

    International Nuclear Information System (INIS)

    Gurarie, V.N.; Jamieson, D.N.; Szymanski, R.; Orlov, A.V.; Williams, J.S.; Conway, M.

    1999-01-01

    Monocrystals of sapphire have been subjected to ion implantation with 86 keV Si - and 80 keV Cr - ions to doses in the range of 5x10 14 -5x10 16 cm -2 prior to thermal stress testing in a pulsed plasma. Above a certain critical dose ion implantation is shown to modify the near-surface structure of samples by introducing damage, which makes crack nucleation easier under the applied stress. The effect of ion dose on the stress resistance is investigated and the critical doses which produce a noticeable change in the stress resistance are determined. The critical dose for Si ions is shown to be much lower than that for Cr - ions. However, for doses exceeding 2x10 16 cm -2 the stress resistance parameter decreases to approximately the same value for both implants. The size of the implantation-induced crack nucleating centers and the density of the implantation-induced defects are considered to be the major factors determining the stress resistance of sapphire crystals irradiated with Si - and Cr - ions

  16. Isotopic effect on thermal physical properties of isotopically modified boron single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Quanli [Japan Science and Technology Corporation, Kawaguchi, Saitama (Japan); Noda, Tetsuji; Suzuki, Hiroshi; Araki, Hiroshi; Numazawa, Takenori; Hirano, Toshiyuki [National Institute for Materials Science, Tsukuba, Ibaraki (Japan); Nogi, Naoyuki; Tanaka, Satoru [University of Tokyo, Department of Quantum Engineering and Systems Science, Tokyo (Japan)

    2002-04-01

    The measurement of specific heat and thermal conductivity at low temperature for isotopically modified boron single crystals was performed between 0.5 and 100K using relaxation method and steady heat flow method, respectively. The results indicate that the specific heat has obvious divergences at T<5K. At 40K, the thermal conductivity of {sup 10}B-enriched crystal is about 570 W/m{center_dot}K, which is 40% larger than that of natural boron crystal. The influence of lattice vibration modes and the isotopic effect on specific heat and thermal conductivity for isotopically modified boron are discussed. (author)

  17. 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

  18. Crystal structure and thermal expansion of CsCaI3:Eu and CsSrBr3:Eu scintillators

    Science.gov (United States)

    Loyd, Matthew; Lindsey, Adam; Patel, Maulik; Koschan, Merry; Melcher, Charles L.; Zhuravleva, Mariya

    2018-01-01

    The distorted-perovskite scintillator materials CsCaI3:Eu and CsSrBr3:Eu prepared as single crystals have shown promising potential for use in radiation detection applications requiring a high light yield and excellent energy resolution. We present a study using high temperature powder X-ray diffraction experiments to examine a deleterious high temperature phase transition. High temperature phases were identified through sequential diffraction pattern Rietveld refinement in GSAS II. We report the linear coefficients of thermal expansion for both high and low temperature phases of each compound. Thermal expansion for both compositions is greatest in the [0 0 1] direction. As a result, Bridgman growth utilizing a seed oriented with the [0 0 1] along the growth direction should be used to mitigate thermal stress.

  19. Lattice Thermal Conductivity of Polyethylene Molecular Crystals from First-Principles Including Nuclear Quantum Effects.

    Science.gov (United States)

    Shulumba, Nina; Hellman, Olle; Minnich, Austin J

    2017-11-03

    Molecular crystals such as polyethylene are of intense interest as flexible thermal conductors, yet their intrinsic upper limits of thermal conductivity remain unknown. Here, we report a study of the vibrational properties and lattice thermal conductivity of a polyethylene molecular crystal using an ab initio approach that rigorously incorporates nuclear quantum motion and finite temperature effects. We obtain a thermal conductivity along the chain direction of around 160  W m^{-1} K^{-1} at room temperature, providing a firm upper bound for the thermal conductivity of this molecular crystal. Furthermore, we show that the inclusion of quantum nuclear effects significantly impacts the thermal conductivity by altering the phase space for three-phonon scattering. Our computational approach paves the way for ab initio studies and computational material discovery of molecular solids free of any adjustable parameters.

  20. 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

  1. 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

  2. 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.

  3. Numerical simulation of convection and heat transfer in Czochralski crystal growth by multiple-relaxation-time LBM

    Science.gov (United States)

    Liu, Ding; Huang, Weichao; Zhang, Ni

    2017-07-01

    A two-dimensional axisymmetric swirling model based on the lattice Boltzmann method (LBM) in a pseudo Cartesian coordinate system is posited to simulate Czochralski (Cz) crystal growth in this paper. Specifically, the multiple-relaxation-time LBM (MRT-LBM) combined with the finite difference method (FDM) is used to analyze the melt convection and heat transfer in the process of Cz crystal growth. An incompressible axisymmetric swirling MRT-LB D2Q9 model is applied to solve for the axial and radial velocities by inserting thermal buoyancy and rotational inertial force into the two-dimensional lattice Boltzmann equation. In addition, the melt temperature and the azimuthal velocity are solved by MRT-LB D2Q5 models, and the crystal temperature is solved by FDM. The comparison results of stream functions values of different methods demonstrate that our hybrid model can be used to simulate the fluid-thermal coupling in the axisymmetric swirling model correctly and effectively. Furthermore, numerical simulations of melt convection and heat transfer are conducted under the conditions of high Grashof (Gr) numbers, within the range of 105 ˜ 107, and different high Reynolds (Re) numbers. The experimental results show our hybrid model can obtain the exact solution of complex crystal-growth models and analyze the fluid-thermal coupling effectively under the combined action of natural convection and forced convection.

  4. 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

  5. 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.

  6. Numerical computation of the linear stability of the diffusion model for crystal growth simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, C.; Sorensen, D.C. [Rice Univ., Houston, TX (United States); Meiron, D.I.; Wedeman, B. [California Institute of Technology, Pasadena, CA (United States)

    1996-12-31

    We consider a computational scheme for determining the linear stability of a diffusion model arising from the simulation of crystal growth. The process of a needle crystal solidifying into some undercooled liquid can be described by the dual diffusion equations with appropriate initial and boundary conditions. Here U{sub t} and U{sub a} denote the temperature of the liquid and solid respectively, and {alpha} represents the thermal diffusivity. At the solid-liquid interface, the motion of the interface denoted by r and the temperature field are related by the conservation relation where n is the unit outward pointing normal to the interface. A basic stationary solution to this free boundary problem can be obtained by writing the equations of motion in a moving frame and transforming the problem to parabolic coordinates. This is known as the Ivantsov parabola solution. Linear stability theory applied to this stationary solution gives rise to an eigenvalue problem of the form.

  7. A thermally tunable inverse opal photonic crystal for monitoring glass transition.

    Science.gov (United States)

    Sun, Liguo; Xie, Zhuoying; Xu, Hua; Xu, Ming; Han, Guozhi; Wang, Cheng; Bai, Xuduo; Gu, ZhongZe

    2012-03-01

    An optical method was developed to monitor the glass transition of the polymer by taking advantage of reflection spectrum change of the thermally tunable inverse opal photonic crystal. The thermally tunable photonic bands of the polymer inverse opal photonic crystal were traceable to the segmental motion of macromolecules, and the segmental motion was temperature dependent. By observing the reflection spectrum change of the polystyrene inverse opal photonic crystal during thermal treatment, the glass transition temperature of polystyrene was gotten. Both changes of the position and intensity of the reflection peak were observed during the glass transition process of the polystyrene inverse opal photonic crystal. The optical change of inverse opal photonic crystal was so large that the glass transition temperature could even be estimated by naked eyes. The glass transition temperature derived from this method was consistent with the values measured by differential scanning calorimeter.

  8. The effect of linear imperfection in [001] direction on the thermal properties of silver crystal

    Directory of Open Access Journals (Sweden)

    J Davoodi

    2013-09-01

    Full Text Available  The aim of this investigation was to calculate the thermal properties of silver crystal in the presence of linear imperfection. The simulations were performed by molecular dynamics simulation technique in NPT as well as NVT ensemble based on quantum Sutton-Chen many body potential. The thermal properties including cohesive energy, melting temperature, isobaric heat capacity and thermal expansion of imperfect silver crystal were calculated and compared to those of the perfect crystal. Moreover, the quantities such as radial distribution function, order parameter and lindemann index were calculated in order to obtain information on crystal structure and disorder in atoms. All calculations were done both with liner imperfection in [001] direction and without imperfection at different temperature. The simulation results show that cohesive energy, linear thermal expansion coefficient increase and melting temperature, latent heat of fusion decrease with increasing linear imperfection. Also, the results show that linear imperfection has no effect on the heat capacity.

  9. Crystal growth and characterization of new nonlinear optical piperidine derivative: (4-hydroxypiperidin-1-yl)(4-methylphenyl) methanone

    Science.gov (United States)

    Revathi, B. K.; Reuben Jonathan, D.; Sathya, S.; Usha, G.

    2018-02-01

    Organic compound (4-hydroxypiperidin-1-yl)(4-methylphenyl) methanone[HPMP] with molecular formula C13H17N O2 was synthesized using Scholten-Boumann condensation reaction method. The single crystals were grown using slow evaporation solution growth technique. Single crystal XRD study shows that the compound crystallizes in the orthorhombic system with a space group Pca21.1H and 13C NMR spectra were recorded to identify the various types of protons and carbons present in the compound and confirm the chemical structure. The Various functional groups present in the compound were identified using recorded FT-IR spectrum. The UV-Visible spectrum study reveals that the crystal is transparent in the entire visible region and the absorption is observed at 236 nm. The PL spectrum shows the emission takes place at 432 nm. The thermal study reveals that the thermal stability of the crystal is good. The Kurtz powder second harmonic generation (SHG) test shows that the HPMP is NLO active and its SHG efficiency is 1.86 times that of KDP. The micro hardness test was carried out and the work hardening coefficient value (n) of the crystal was found to be 2.20. This indicates that the crystal is hard and is suitable for device application.

  10. Growth and physicochemical properties of second-order nonlinear optical 2-amino-5-chloropyridinium trichloroacetate single crystals

    Science.gov (United States)

    Renugadevi, R.; Kesavasamy, R.

    2015-09-01

    The growth of organic nonlinear optical (NLO) crystal 2-amino-5-chloropyridinium trichloroacetate (2A5CPTCA) has been synthesized and single crystals have been grown from methanol solvent by slow evaporation technique. The grown crystals were subjected to various characterization analyses in order to find out the suitability for device fabrication. Single crystal X-ray diffraction analysis reveals that 2A5CPTCA crystallizes in monoclinic system with the space group Cc. The grown crystal was further characterized by Fourier transform infrared spectral analysis to find out the functional groups. The nuclear magnetic resonance spectroscopy is a research technique that exploits the magnetic properties of certain atomic nuclei. The optical transparency window in the visible and near-IR (200--1100 nm) regions was found to be good for NLO applications. Thermogravimetric analysis and differential thermal analysis were used to study its thermal properties. The powder second harmonic generation efficiency measurement with Nd:YAG laser (1064 nm) radiation shows that the highest value when compared with the standard potassium dihydrogen phosphate crystal.

  11. 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

  12. Growth-melt asymmetry in ice crystals under the influence of spruce budworm antifreeze protein

    Energy Technology Data Exchange (ETDEWEB)

    Pertaya, Natalya [Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Celik, Yeliz [Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); DiPrinzio, Carlos L [Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States); Wettlaufer, J S [Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109 (United States); Davies, Peter L [Department of Biochemistry, Queen' s University, Kingston, ON K7L 3N6 (Canada); Braslavsky, Ido [Department of Physics and Astronomy, Ohio University, Athens, OH 45701 (United States)

    2007-10-17

    Here we describe studies of the crystallization behavior of ice in an aqueous solution of spruce budworm antifreeze protein (sbwAFP) at atmospheric pressure. SbwAFP is an ice binding protein with high thermal hysteresis activity, which helps protect Choristoneura fumiferana (spruce budworm) larvae from freezing as they overwinter in the spruce and fir forests of the north eastern United States and Canada. Different types of ice binding proteins have been found in many other species. They have a wide range of applications in cryomedicine and cryopreservation, as well as the potential to protect plants and vegetables from frost damage through genetic engineering. However, there is much to learn regarding the mechanism of action of ice binding proteins. In our experiments, a solution containing sbwAFP was rapidly frozen and then melted back, thereby allowing us to produce small single crystals. These maintained their hexagonal shapes during cooling within the thermal hysteresis gap. Melt-growth-melt sequences in low concentrations of sbwAFP reveal the same shape transitions as are found in pure ice crystals at low temperature (-22 deg. C) and high pressure (2000 bar) (Cahoon et al 2006 Phys. Rev. Lett. 96 255502); while both growth and melt shapes display faceted hexagonal morphology, they are rotated 30 deg. relative to one another. Moreover, the initial melt shape and orientation is recovered in the sequence. To visualize the binding of sbwAFP to ice, we labeled the antifreeze protein with enhanced green fluorescent protein (eGFP) and observed the sbwAFP-GFP molecules directly on ice crystals using confocal microscopy. When cooling the ice crystals, facets form on the six primary prism planes (slowest growing planes) that are evenly decorated with sbwAFP-GFP. During melting, apparent facets form on secondary prism planes (fastest melting planes), leaving residual sbwAFP at the six corners of the hexagon. Thus, the same general growth-melt behavior of an apparently

  13. 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

  14. 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.

  15. Liquid-Crystal Display (LCD) Screen Thermal Testing to Simulate Solar Gain

    Science.gov (United States)

    2015-12-01

    ARL-TN-0723 ● DEC 2015 US Army Research Laboratory Liquid - Crystal Display (LCD) Screen Thermal Testing to Simulate Solar Gain...longer needed. Do not return it to the originator. ARL-TN-0723 ● DEC 2015 US Army Research Laboratory Liquid - Crystal Display (LCD...1. REPORT DATE (DD-MM-YYYY) December 2015 2. REPORT TYPE Final 3. DATES COVERED (From - To) 09/2013 4. TITLE AND SUBTITLE Liquid - Crystal

  16. The Effects of Thermal History on Nucleation of Tetragonal Lysozyme Crystals, or Hot Protein and Cold Nucleation

    Science.gov (United States)

    Burke, Michael; Judge, Russell; Pusey, Marc

    2000-01-01

    Chicken egg white lysozyme has a well characterized thermally driven phase transition. Between pH 4.2 and 5.2, the transition temperature, as defined by the point where the tetragonal and orthorhombic solubilities are equal, is a function of the pH, salt (precipitant) type and concentration, and most likely of the buffer concentration as well. This phase transition can be carried out with protein solution alone, prior to addition of precipitant solution. Warming a lysozyme solution above the phase transition point, then cooling it back below this point, has been shown to affect the subsequent nucleation rate, as determined by the numbers and size of crystals formed, but not the growth rate for the tetragonal crystal form . We have now measured the kinetics of this process and investigated its reversibility. The transition effects are progressive with temperature, having a half time of about 1 hour at 37C at pH 4.8. After holding a lysozyme solution at 37C (prior to addition of precipitant) for 16 hours, then cooling it back to 4C no return to the pre-warmed nucleation kinetics are observed after at least 4 weeks. Orthorhombic lysozyme crystals apparently do not undergo the flow-induced growth cessation of tetragonal lysozyme crystals. Putting the protein in the orthorhombic form does not affect the averaged face growth kinetics, only nucleation, for tetragonal crystals. This differential behaviour may be exploited to elucidate how and where flow affects the lysozyme crystal growth process. The presentation will focus on the results of these and ongoing studies in this area.

  17. 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

  18. Crystal growth and second harmonic generation efficiency of a chalcone derivative

    Science.gov (United States)

    Meenatchi, V.; Muthu, K.; Rajasekar, M.; Meenakshisundaram, SP.

    2013-06-01

    Single crystals of (2E,6E)-2-(4-fluorobenzylidine)-6-(4-methoxybenzylidine)cyclohexanone (FBMBC) have been grown by a slow evaporation solution growth technique from ethanol at room temperature. The single crystal X-ray diffraction study reveals that the FBMBC belongs to triclinic system and the cell parameters are a=9.790(6) Å, b=12.08(7) Å, c=14.09(9) Å and V=1577 Å3. The structure and the crystallinity of the material were further confirmed by powder X-ray diffraction analysis. The various functional groups present in the molecule are confirmed by Fourier transform infrared spectral analysis. The scanning electron microscopy study reveals the surface morphology of the as-grown crystal. Thermogravimetric/differential thermal analysis studies reveal the purity of the material and the crystals are transparent in the visible region having a low optical cut-off at ∼475 nm. The second harmonic generation efficiency of FBMBC is estimated by the Kurtz and Perry technique. Theoretical calculations were performed using the Hartree-Fock method with 6-31 G(d,p) as the basis set to derive the optimized geometry and the first-order molecular hyperpolarizability (β) values.

  19. Crystal growth and second harmonic generation efficiency of a chalcone derivative

    Energy Technology Data Exchange (ETDEWEB)

    Meenatchi, V.; Muthu, K.; Rajasekar, M.; Meenakshisundaram, SP., E-mail: aumats2009@gmail.com

    2013-06-15

    Single crystals of (2E,6E)-2-(4-fluorobenzylidine)-6-(4-methoxybenzylidine)cyclohexanone (FBMBC) have been grown by a slow evaporation solution growth technique from ethanol at room temperature. The single crystal X-ray diffraction study reveals that the FBMBC belongs to triclinic system and the cell parameters are a=9.790(6) Å, b=12.08(7) Å, c=14.09(9) Å and V=1577 Å{sup 3}. The structure and the crystallinity of the material were further confirmed by powder X-ray diffraction analysis. The various functional groups present in the molecule are confirmed by Fourier transform infrared spectral analysis. The scanning electron microscopy study reveals the surface morphology of the as-grown crystal. Thermogravimetric/differential thermal analysis studies reveal the purity of the material and the crystals are transparent in the visible region having a low optical cut-off at ∼475 nm. The second harmonic generation efficiency of FBMBC is estimated by the Kurtz and Perry technique. Theoretical calculations were performed using the Hartree–Fock method with 6-31 G(d,p) as the basis set to derive the optimized geometry and the first-order molecular hyperpolarizability (β) values.

  20. Numerical investigation of thermal and residual stress of sapphire during c-axis vertical Bridgman growth process considering the solidification history effect

    Science.gov (United States)

    Hwang, Ji Hoon; Lee, Young Cheol; Lee, Wook Jin

    2018-01-01

    Sapphire single crystals have been highlighted for epitaxial of gallium nitride films in high-power laser and light emitting diode industries. In this study, the evolution of thermally induced stress in sapphire during the vertical Bridgman crystal growth process was investigated using a finite element model that simplified the real Bridgman process. A vertical Bridgman process of cylindrical sapphire crystal with a diameter of 50 mm was considered for the model. The solidification history effect during the growth was modeled by the quite element technique. The effects of temperature gradient, seeding interface shape and seeding position on the thermal stress during the process were discussed based on the finite element analysis results.

  1. 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.

  2. 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.

  3. 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

  4. 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...

  5. Control of the structural parameters in the (Zn – Zn16Ti single crystal growth

    Directory of Open Access Journals (Sweden)

    W. Wołczyński

    2011-10-01

    Full Text Available The (Zn - single crystal was obtained by means of the Bridgman system. Several growth rates were applied during the experiment. The graphite crucible was used in order to perform the solidification process. The unidirectional solidification occurred with the presence of the moving temperature field. The thermal gradient was positive so that the constrained growth of the single crystal was ensured. The (Zn single crystal was doped with small addition of titanium and copper. The titanium formed an intermetallic compound Zn16-Ti. The copper was solved in the solid solution (Zn. The precipitates of (Zn and Zn16-Ti formed a stripes localized cyclically along the single crystal length. The intermetallic compound Zn16-Ti strengthened the (Zn single crystal. The structural transitions were observed in the stripes with the increasing solidification rate. Within the first range of the solidification rates ( the irregular L-shape rod-like intermetalliccompoundwas revealed. At the- threshold growth rate branches disappear continuously till the growth rate equal to. At the same range of growth rates the regular lamellar eutectic structure (Zn – Zn16-Ti appeared continuously and it existed exclusively till the second threshold growth rate equal to. Above the second threshold growth rate the regular rod-like eutectic structure was formed, only. Thegeneral theory for the stationary eutectic solidification was developed. According to this theory the eutectic structure localized within the stripes is formed under stationary state. Therefore, the criterion of the minimum entropy production defines well the stationary solidification. The entropy production was calculated for the regular rod-like eutectic structure formation and for the regular lamellar eutectic structure formation. It was postulated that the observed structure are subjected to the competition. That is why the structural transitionwere observed at therevealedthreshold growth rates.Moreover, it was

  6. 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.

  7. 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.

  8. 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.)

  9. Thermal tuning of a silicon photonic crystal cavity infilled with an elastomer

    NARCIS (Netherlands)

    Erdamar, A.K.; Van Leest, M.M.; Picken, S.J.; Caro, J.

    2011-01-01

    Thermal tuning of the transmission of an elastomer infilled photonic crystal cavity is studied. An elastomer has a thermal expansion-induced negative thermo-optic coefficient that leads to a strong decrease of the refractive index upon heating. This property makes elastomer highly suitable for

  10. Full-scale experiments on solid-pellets feed continuous Czochralski growth of silicon crystals

    Science.gov (United States)

    Anselmo, A.; Koziol, J.; Prasad, V.

    1996-06-01

    Two long-term solid-pellets feed continuous Czochralski growth experiments were performed in an industrial Czochralski crystal puller as an extension to our previous work [7]. The goals of these experiments were to examine how polysilicon pellets would melt in a standard Cz system, to discover the thermal effects the pellets would have on the overall melt, and to find if pellet addition could be an effective melt replenishment technique. These experiments demonstrate that the quality of the melt for the CCz growth is based heavily on the surface temperature of the melt. A novel characterization method ("impact severity") is developed to characterize the quality of the CCz melt. Stable feed rate and melt conditions were achieved for three different pull rates. These experiments demonstrate that the process is technically feasible, and can be retrofitted to the existing industrial systems. Several critical issues that need to be addressed to develop a successful CCz process are also discussed.

  11. Thermal tunability of photonic bandgaps in liquid crystal infiltrated microstructured polymer optical fibers

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Wei, Lei; Alkeskjold, Thomas Tanggaard

    2009-01-01

    We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used to demons......We demonstrate the photonic bandgap effect and the thermal tunability of bandgaps in microstructured polymer optical fibers infiltrated with liquid crystal. Two liquid crystals with opposite sign of the temperature gradient of the ordinary refractive index (E7 and MDA-00- 1444) are used...... to demonstrate that both signs of the thermal tunability of the bandgaps are possible. The useful bandgaps are ultimately bounded to the visible range by the transparency window of the polymer....

  12. Thermalization calorimetry: A simple method for investigating glass transition and crystallization of supercooled liquids

    DEFF Research Database (Denmark)

    Jakobsen, Bo; Sanz, Alejandro; Niss, Kristine

    2016-01-01

    and their crystallization, e.g., for locating the glass transition and melting point(s), as well as for investigating the stability against crystallization and estimating the relative change in specific heat between the solid and liquid phases at the glass transition......We present a simple method for fast and cheap thermal analysis on supercooled glass-forming liquids. This “Thermalization Calorimetry” technique is based on monitoring the temperature and its rate of change during heating or cooling of a sample for which the thermal power input comes from heat...

  13. 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

  14. Growth and physicochemical properties of organometallic (DL)-trithioureatartrato-O1,O2,O3-cadmium(II) single crystals

    Science.gov (United States)

    Sathyamoorthy, K.; Vinothkumar, P.; Irshad Ahamed, J.; Murali Manohar, P.; Priya, M.; Liu, Jinghe

    2018-04-01

    Single crystals of organometallic (DL)-trithioureatartrato-O1,O2,O3-cadmium(II) (TUDLC) have been grown from methanol solution by using the slow evaporation of solvent growth technique. The lattice structure and crystalline perfection have been determined by carrying out single crystal X-ray diffraction and high resolution X-ray diffraction measurements. The grown crystal was characterized thermally and mechanically by carrying out thermo-gravimetric and micro hardness measurements. The linear and nonlinear optical characterizations were made by carrying out optical transmittance, surface laser damage threshold, particle size-dependent second harmonic generation (SHG) efficiency and photo conductivity measurements. The grown crystal was electrically characterized by carrying out frequency-dependent dielectric measurements. Chemical etching study was also carried out and the dislocation density was estimated. Results obtained in the present study indicate that the grown TUDLC crystal is optically transparent with lower cut-off wavelength 304 nm, mechanically soft, thermally stable up to 101 °C and NLO active with SHG efficiency 2.13 (in KDP unit). The grown crystal is found to have considerably large size, good crystalline perfection, large specific heat capacity, higher surface laser damage threshold and negative photoconductivity.

  15. Spatial distribution of gamma-crystals in metallocene-made isotactic polypropylene crystallized under combined thermal and flow fields.

    Science.gov (United States)

    Wang, Yan; Pan, Ji-Lin; Mao, Yimin; Li, Zhong-Ming; Li, Liangbin; Hsiao, Benjamin S

    2010-05-27

    The present Article reports the relationships between molecular orientation, formation, and spatial distribution of gamma-crystals in metallocene-made isotactic polypropylene (m-iPP) samples prepared by two industrial processes: conventional injection molding (CIM) and oscillatory shear injection molding (OSIM), in which combined thermal and flow fields typically exist. In particular, spatial distributions of crystallinity, fraction of gamma-crystal (f(gamma)) with respect to alpha-crystal, and lamella-branched shish-kebab structure in the shaped samples were characterized by synchrotron two-dimensional (2D) wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. The results showed that the crystallinity in any given region of OSIM samples was always higher than that of CIM samples. The value of f(gamma) increased monotonously from skin to core in CIM samples, whereas the corresponding f(gamma) increased nonmonotonically in OSIM samples. The spatial distribution of gamma-crystal in OSIM samples can be explained by the epitaxial arrangement between gamma- and alpha-crystal in a lamella-branched shish-kebab structure. In the proposed model, the parent lamellae of alpha-crystal provide secondary nucleation sites for daughter lamellae of alpha-crystal and gamma-crystal, and the different content of parent lamellae results in varying amounts of gamma-crystal. In OSIM samples, the smallest parent-daughter ratio ([R]) = 1.38) in the core region led to the lowest fraction of gamma-crystal (0.57), but relatively higher gamma-crystal content (0.69) at 600 and 1200 mum depth of the samples (corresponding to [R] of 4.5 and 5.8, respectively). This is consistent with the proposed model where more parent lamellae provide more nucleation sites for crystallization, thus resulting in higher content of gamma-crystal. The melting behavior of CIM and OSIM samples was studied by differential scanning calorimetery (DSC). The observed double-melting peaks

  16. Spatial Distribution of -Crystals in Metallocene-Made Isotactic Polypropylene Crystallized under Combined Thermal and Flow Fields

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Pan, J; Mao, Y; Li, Z; Li, L; Hsiao, B

    2010-01-01

    The present Article reports the relationships between molecular orientation, formation, and spatial distribution of {gamma}-crystals in metallocene-made isotactic polypropylene (m-iPP) samples prepared by two industrial processes: conventional injection molding (CIM) and oscillatory shear injection molding (OSIM), in which combined thermal and flow fields typically exist. In particular, spatial distributions of crystallinity, fraction of {gamma}-crystal (f{gamma}) with respect to {alpha}-crystal, and lamella-branched shish-kebab structure in the shaped samples were characterized by synchrotron two-dimensional (2D) wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. The results showed that the crystallinity in any given region of OSIM samples was always higher than that of CIM samples. The value of f{gamma} increased monotonously from skin to core in CIM samples, whereas the corresponding f{gamma} increased nonmonotonically in OSIM samples. The spatial distribution of {gamma}-crystal in OSIM samples can be explained by the epitaxial arrangement between {gamma}- and {alpha}-crystal in a lamella-branched shish-kebab structure. In the proposed model, the parent lamellae of {alpha}-crystal provide secondary nucleation sites for daughter lamellae of {alpha}-crystal and {gamma}-crystal, and the different content of parent lamellae results in varying amounts of {gamma}-crystal. In OSIM samples, the smallest parent-daughter ratio ([R] = 1.38) in the core region led to the lowest fraction of {gamma}-crystal (0.57), but relatively higher {gamma}-crystal content (0.69) at 600 and 1200 {micro}m depth of the samples (corresponding to [R] of 4.5 and 5.8, respectively). This is consistent with the proposed model where more parent lamellae provide more nucleation sites for crystallization, thus resulting in higher content of {gamma}-crystal. The melting behavior of CIM and OSIM samples was studied by differential scanning calorimetery (DSC). The

  17. ORTEP-III: Oak Ridge Thermal Ellipsoid Plot Program for crystal structure illustrations

    Energy Technology Data Exchange (ETDEWEB)

    Burnett, M.N.; Johnson, C.K.

    1996-07-01

    This report describes a computer program for drawing crystal structure illustrations. Ball-and-stick type illustrations of a quality suitable for publication are produced with either spheres or thermal-motion probability ellipsoids on the atomic sites. The program can also produce stereoscopic pairs of illustrations which aid in the visualization of complex packing arrangements of atoms and thermal motion patterns. Interatomic distances, bond angles, and principal axes of thermal motion are also calculated to aid the structural study.

  18. THERMAL LENSING MEASUREMENTS IN THE ANISOTROPIC LASER CRYSTALS UNDER DIODE PUMPING

    Directory of Open Access Journals (Sweden)

    P. A. Loiko

    2012-01-01

    Full Text Available An experimental setup was developed for thermal lensing measurements in the anisotropic diode-pumped laser crystals. The studied crystal is placed into the stable two-mirror laser cavity operating at the fundamental transversal mode. The output beam radius is measured with respect to the pump intensity for different meridional planes (all these planes contain the light propagation direction. These dependencies are fitted using the ABCD matrix method in order to obtain the sensitivity factors showing the change of the optical power of thermal lens due to variation of the pump intensity. The difference of the sensitivity factors for two mutually orthogonal principal meridional planes describes the thermal lens astigmatism degree. By means of this approach, thermal lensing was characterized in the diode-pumped monoclinic Np-cut Nd:KGd(WO42 laser crystal at the wavelength of 1.067 μm for light polarization E || Nm.

  19. 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.

  20. 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

  1. 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.

  2. 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.)

  3. Synthesis, growth, structure, mechanical and optical properties of a new semi-organic 2-methyl imidazolium dihydrogen phosphate single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Nagapandiselvi, P., E-mail: nagapandiselvip@ssn.edu.in [Department of Physics, SSN College of Engineering, Kalavakkam (India); Baby, C. [Sophisticated Analytical Instrument Facility, Indian Institute of Technology Madras, Chennai (India); Gopalakrishnan, R. [Crystal Research Lab, Department of Physics, Anna University, Chennai (India)

    2016-09-15

    Highlights: • 2MIDP crystals were grown by slow evaporation solution growth technique. • Single crystal XRD revealed self-assembled supramolecular framework. • Z scan technique is employed for third order nonlinear optical susceptibility. • Structure-property correlation is established. - Abstract: A new semi-organic compound, 2-methyl imidazolium dihydrogen phosphate (2MIDP), was prepared and good quality single crystals of 2MIDP were grown by slow evaporation solution growth technique. Crystal structure elucidated using Single crystal XRD showed that 2MIDP crystallizes in monoclinic system with P2{sub 1}/c space group. FT-IR, UV-Vis-NIR, Fluorescence and FT-NMR spectra confirm the molecular structure of 2MIDP. The UV-Vis-NIR spectra established the suitability of the compound for NLO applications. TG-DSC showed that 2MIDP is thermally stable up to 200 °C. Mechanical characteristics like hardness number (H{sub v}), stiffness constant (C{sub 11}), yield strength (σ{sub v}), fracture toughness (K{sub c}) and brittleness index (B{sub i}) were assessed using Vicker’s microhardness tester. Third order nonlinear optical properties determined from Z-scan measurement using femto and picosecond lasers showed two photon reverse saturable absorption. The enhancement of nonlinear optical properties in femto second laser, revealed the suitability of 2MIDP for optical limiting applications.

  4. 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)

  5. 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.

  6. Spray-Dried Cellulose Nanofibril-Reinforced Polypropylene Composites for Extrusion-Based Additive Manufacturing: Nonisothermal Crystallization Kinetics and Thermal Expansion

    Directory of Open Access Journals (Sweden)

    Lu Wang

    2018-02-01

    Full Text Available Isotactic polypropylene (iPP is a versatile polymer. It accounts for the second-largest polymer consumption worldwide. However, iPP is difficult to 3D print via extrusion-based processing. This is attributable to its rapid crystallization rate. In this study, spray-dried cellulose nanofibrils (SDCNF and maleic anhydride polypropylene (MAPP were investigated to reveal their effects on the nonisothermal crystallization kinetics and thermal expansion of iPP. SDCNF at 3 wt % and 30 wt % accelerated the crystallization rate of iPP, while SDCNF at 10 wt % retarded the crystallization rate by restricting crystal growth and moderately increasing the nucleation density of iPP. Additionally, adding MAPP into iPP/SDCNF composites accelerated the crystallization rate of iPP. The effective activation energy of iPP increased when more than 10 wt % SDCNF was added. Scanning electron microscopy and polarized light microscopy results indicated that high SDCNF content led to a reduced gap size among SDCNF, which hindered the iPP crystal growth. The coefficient of thermal expansion of iPP/SDCNF10% was 11.7% lower than the neat iPP. In summary, SDCNF, at 10 wt %, can be used to reduce the warping of iPP during extrusion-based additive manufacturing.

  7. XRD- and infrared-probed anisotropic thermal expansion properties of an organic semiconducting single crystal.

    Science.gov (United States)

    Mohanraj, J; Capria, E; Benevoli, L; Perucchi, A; Demitri, N; Fraleoni-Morgera, A

    2018-01-17

    The anisotropic thermal expansion properties of an organic semiconducting single crystal constituted by 4-hydroxycyanobenzene (4HCB) have been probed by XRD in the range 120-300 K. The anisotropic thermal expansion coefficients for the three crystallographic axes and for the crystal volume have been determined. A careful analysis of the crystal structure revealed that the two different H-bonds stemming from the two independent, differently oriented 4HCB molecules composing the unit cell have different rearrangement patterns upon temperature variations, in terms of both bond length and bond angle. Linearly Polarized Mid InfraRed (LP-MIR) measurements carried out in the same temperature range, focused on the O-H bond spectral region, confirm this finding. The same LP-MIR measurements, on the basis of a semi-empirical relation and of geometrical considerations and assumptions, allowed calculation of the -CNH-O- hydrogen bond length along the a and b axes of the crystal. In turn, the so-calculated -CNH-O- bond lengths were used to derive the thermal expansion coefficients along the corresponding crystal axes, as well as the volumetric one, using just the LP-MIR data. Reasonable to good agreement with the same values obtained from XRD measurements was obtained. This proof-of-principle opens interesting perspectives about the possible development of a rapid, low cost and industry-friendly assessment of the thermal expansion properties of organic semiconducting single crystals (OSSCs) involving hydrogen bonds.

  8. 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.

  9. Influence of materials' property of laser crystal on thermal effects in high-power DPL

    Science.gov (United States)

    Dai, Qin; Li, Xin-zhong; Wu, Ri-na; Xu, Song-ning

    2009-07-01

    The physical property parameters of laser crystal in solid state lasers vary strongly with temperature, which will intensely affect the thermal effects of high power LD pumping solid state laser (DPL). In this study, by correcting the intensity distribution of the laser beam emitted from the pumping source of laser diodes, a heat transmission model for the laser crystal of a side-pumping geometry with a triangle uniform distribution was established. The temperature and stress distribution are calculated and compared using finite element method under two different conditions, which thermal conductivity, heat capacity and coefficient of thermal expansion of the laser crystal media vary with the temperature, and these physical property parameters are constant. The results show that temperature at the center of laser crystal media will further increase, and there will produce an additional stress except for thermal stress due to the temperature gradient at the radial direction in the laser crystal, which result in more serious thermal effects. This study provides a more visual and accurate reference model for the design and optimization of high power laser diode side pumped solid state lasers.

  10. 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.

  11. Crystal growth and optical properties of CdS-doped lead silicate glass

    International Nuclear Information System (INIS)

    Liu Hao; Liu Qiming; Zhao Xiujian

    2007-01-01

    The crystal growth and optical properties of CdS microcrystallite-doped lead silicate glass is investigated in this paper. The existence of CdS nanocrystals was confirmed via X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results reveal that a two-stage heat-treat procedure can produce a better size distribution of CdS nanocrystals than a one-stage heat-treat procedure in glasses. The second harmonic generation (SHG) from the base glass and CdS microcrystallite doped glasses was observed, and the effects of the heat treatments and the thermal poling temperature on the crystallization of CdS and second-order harmonic (SH) intensity were discussed, respectively. It is indicated that samples doped with CdS microcrystallite showed larger SH intensity than that of the base glass. Use of a higher thermal poling temperature than the glass transformation temperature does not result in a good SH intensity in glasses

  12. 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.

  13. 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.

  14. 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 ...

  15. Growth and characterization of lead-free (K,Na)NbO3-based piezoelectric single crystals

    International Nuclear Information System (INIS)

    Liu, Hairui

    2016-01-01

    Lead-free piezoelectric materials have received increasing attention in the last decade, driven by environmental issues and health concerns. Of considerable interest is the (K,Na)NbO 3 (KNN)-based system, which possesses a relatively high Curie temperature and good piezoelectric properties. Abundant publications on KNN-based polycrystalline ceramics increased the interest in studying their single-crystalline form, based on two major concerns. The first concern refers to the negative role of grain interactions on the electromechanical response. The second concern deals with domain engineering. The relationship between external electric field direction, crystallographic orientation, and spontaneous polarization vectors for a specific structure can be more readily established in single crystals and thus offers a pathway for an in-depth understanding of fundamental mechanism and potential applications. The exciting enhancement of both piezoelectric and ferroelectric response in lead-based single crystals also encourages the further exploration of KNN-based piezoelectric crystals, as they possess the same perovskite structure. The main goal of this thesis is to find possible approaches for improved electromechanical properties in KNN-based piezoelectric single crystals. In Chapter 2, the current development of KNN-based single crystals as piezoelectrics is reviewed, following a short introduction of fundamental knowledge on piezoelectrics and ferroelectrics. Both submerged-seed solution growth and top-seeded solution growth techniques were employed to produce single crystals, as described detailed in Chapter 3. Emphasis is subsequently placed on issues of the crystal growth process, effective methods to enhance electrical properties, and crystallographic orientation-dependent electrical properties in Li-, Ta-, and/or Sb-substituted KNN single crystals. The main conclusions from the crystal growth aspect are presented in Chapter 4 and can be summarized as follows: (i

  16. 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.

  17. 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

  18. Bulk crystal growth and their effective third order nonlinear optical properties of 2-(4-fluorobenzylidene) malononitrile (FBM) single crystal

    Science.gov (United States)

    Priyadharshini, A.; Kalainathan, S.

    2018-04-01

    2-(4-fluorobenzylidene) malononitrile (FBM), an organic third order nonlinear (TONLO) single crystal with the dimensions of 32 × 7 × 11 mm3, has been successfully grown in acetone solution by slow evaporation technique at 35 °C. The crystal system (triclinic), space group (P-1) and crystalline purity of the titular crystal were measured by single crystal and powder X-ray diffraction, respectively. The molecular weight and the multiple functional groups of the FBM material were confirmed through the mass and FT-IR spectral analysis. UV-Vis-NIR spectral study enroles that the FBM crystal exhibits excellent transparency (83%) in the entire visible and near infra-red region with a wide bandgap 2.90 eV. The low dielectric constant (εr) value of FBM crystal is appreciable for microelectronics industry applications. Thermal stability and melting point (130.09 °C) were ascertained by TGA-DSC analysis. The laser-induced surface damage threshold (LDT) value of FBM specimen is found to be 2.14 GW/cm2, it is fairly good compared to other reported NLO crystals. The third - order nonlinear optical character of the FBM crystal was confirmed through the typical single beam Z-scan technique. All these finding authorized that the organic crystal of FBM is favorably suitable for NLO applications.

  19. 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.

  20. Hot Views on Cold Crystals: The Application of Thermal Imaging in Cryo-crystallography

    Science.gov (United States)

    Snell, E. H.; vanderWoerd, M. J.; Deacon, A.

    2003-01-01

    In the past we have used thermal imaging techniques to visualize the cryocooling processes of macromolecular crystals. From these images it was clear that a cold wave progresses through a crystal starting at the face closest to the origin of the cold stream and ending at the point furthest away. During these studies we used large volume crystals, which were clearly distinguished from the loop holding them. These large crystals, originally grown for neutron diffraction studies, were chosen deliberately to enhance the imaging. As an extension to this work, we present used thermal imaging to study small crystals, held in a cryo-loop, in the presence of vitrified mother liquor. The different infrared transmission and reflectance properties of the crystal in comparison to the mother liquor surrounding it are thought to be the parameter that produces the contrast that makes the crystal visible. An application of this technology may be the determination of the exact location of small crystals in a cryo-loop. Data from initial tests in support of application development was recorded for lysozyme crystals and for bFGF/dna complex crystals, which were cryo-cooled and imaged in large loops, both with visible light and with infrared radiation. The crystals were clearly distinguished from the vitrified solution in the infrared spectrum, while in the case of the bFGF/dna complex the illumination had to be carefully manipulated to make the crystal visible in the visible spectrum. These results suggest that the thermal imaging may be more sensitive than visual imaging for automated location of small crystals. However, further work on small crystals robotically mounted at SSRL did not clearly visualize those crystals. The depth of field of the camera proved to be limiting and a different cooling geometry was used, compared to the previous, successful experiments. Analysis to exploit multiple images to improve depth of field and experimental work to understand cooling geometry

  1. Hot Views on Cold Crystals: The Application of Thermal Imaging in Cryocrystallography

    Science.gov (United States)

    Snell, Eddie H.

    2003-01-01

    In the past we have used thermal imaging techniques to visualize the cryocooling processes of macromolecular crystals. From these images it was clear that a cold wave progresses through a crystal starting at the face closest to the origin of the cold stream and ending at the point furthest away. During these studies we used large volume crystals, which were clearly distinguished from the loop holding them. These large crystals, originally grown for neutron diffraction studies, were chosen deliberately to enhance the imaging. As an extension to this work, we used thermal imaging to study small crystals, held in a cryo- loop, in the presence of vitrified mother liquor. The different infrared transmission and reflectance properties of the crystal in comparison to the mother liquor surrounding it are thought to be the parameter that produces the contrast that makes the crystal visible. An application of this technology may be the determination of the exact location of small crystals in a cryo-loop. Data from initial tests in support of application development was recorded for lysozyme crystals and for bFGF/dna complex crystals, which were cryo-cooled and imaged in large loops, both with visible light and with infrared radiation. The crystals were clearly distinguished from the vitrified solution in the infrared spectrum, while in the case of the bFGF/dna complex the illumination had to be carefully manipulated to make the crystal visible in the visible spectrum. These results suggest that the thermal imaging may be more sensitive than visual imaging for automated location of small crystals. However, further work on small crystals robotically mounted at SSRL did not clearly visualize those crystals. The depth of field of the camera proved to be limiting and a different cooling geometry was used, compared to the previous, successful experiments. Analysis to exploit multiple images to improve depth of field and experimental work to understand cooling geometry effects is

  2. 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.

  3. 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.

  4. Normal processes of phonon-phonon scattering and thermal conductivity of germanium crystals with isotopic disorder

    CERN Document Server

    Kuleev, I G

    2001-01-01

    The effect of normal processes of the phonon-phonon scattering on the thermal conductivity of the germanium crystals with various isotopic disorder degrees is considered. The phonon pulse redistribution in the normal scattering processes both inside each oscillatory branch (the Simons mechanism) and between various phonon oscillatory branches (the Herring mechanism) is accounted for. The contributions of the longitudinal and cross-sectional phonons drift motion into the thermal conductivity are analyzed. It is shown that the pulse redistribution in the Herring relaxation mechanism leads to essential suppression of the longitudinal phonons drift motion in the isotopically pure germanium crystals. The calculations results of thermal conductivity for the Herring relaxation mechanism agree well with experimental data on the germanium crystals with various isotopic disorder degrees

  5. Tris(dithiocarboxylato)indium(III): Thermal studies and crystal ...

    Indian Academy of Sciences (India)

    WINTEC

    as a single source precursor for the preparation of metal sulfide thin films and nanoparticles has been realized only .... thoroughly with methanol and dried in vacuo. 2.3 Crystallography. Intensity data for single crystal of .... as ethylene glycol (190°C), 1,4-butane diol (230°C), polyethylene glycol (290°C) and hexadecylamine.

  6. Thermal behaviour of strontium tartrate single crystals grown in gel

    Indian Academy of Sciences (India)

    Unknown

    lengths of the diffusing ions increase which slow down the vertical displacement of the ions due to the increased resistance of the extra path which the ions have to travel. In effect this is equivalent to reducing the diffusion coeffi- cient of the medium. The observed delay in the time of formation of the crystal in magnetic field is ...

  7. 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)

  8. Effect of controlled crucible movement on melting process and carbon contamination in Czochralski silicon crystal growth

    Science.gov (United States)

    Liu, Xin; Han, Xue-Feng; Nakano, Satoshi; Kakimoto, Koichi

    2018-02-01

    In Czochralski silicon (CZ-Si) crystal growth, packed Si chunks experience collapse and volume shrinkage during the melting process. The axial movements of the crucible and the melting of the Si feedstock lead to dynamic thermal and flow fields and affect mass transport. To study the effect of crucible movement on the melting process and carbon (C) contamination, the cases of fixed and lifting crucible were investigated by the transient global simulation with dynamic mesh deformation. The gap width between the gas-guide and the top surface of Si feedstock was kept constant during the crucible lifting process. Impurity and species transport in Si feedstock and argon gas was investigated for the cases with the fixed and lifting crucibles. The comparison of C accumulation processes indicated that the lifting crucible case resulted in higher C contamination than that found in the fixed crucible case. Furthermore, lifting crucible cases with different gap widths were investigated to elaborate strategies for controlling the crucible movement for its effect on the melting process and C contamination in CZ-Si crystal growth. It was observed that the optimum gap width for C reduction results from the trade-off between the back diffusion and gas convection.

  9. 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.

  10. Growth and crystal structure of solid solutions SrAl0.5Ta0.5O3:LaAlO3

    International Nuclear Information System (INIS)

    Berkowski, M.; Fink-Finowicki, J.; Aleksiyko, R.; Kikalejshvili-Domukhovska, R.; Byszewski, P.; Diduszko, R.

    2003-01-01

    Crystals (SrAl 0.5 Ta 0.5 O 3 ) 1-x :(LaAlO 3 ) x ((SAT) 1-x (LA) x ) were obtained by the Czochralski and floating zone method in whole composition range; structure of this crystals was investigated by x-ray measurements. A schematic phase diagram of this solution is propose; it was found that solid solutions exist at concentration 0≤x≤0.5 and crystals adopt cubic structure. The Czochralski method was successfully used to growth of single crystals with x = 0.23 - 0.41. Structural phase transformations and tendency to formation of twins were no stated. The proper range of lattice parameters and high melting point close to 1850 o C indicate their high thermal and chemical stability. Therefore these crystals may be used as substrates for the growth of HTSc, manganites or GaN epitaxial layers. (author)

  11. 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.

  12. 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.

  13. Seedless Growth of Bismuth Nanowire Array via Vacuum Thermal Evaporation

    Science.gov (United States)

    Liu, Mingzhao; Nam, Chang-Yong; Zhang, Lihua

    2015-01-01

    Here a seedless and template-free technique is demonstrated to scalably grow bismuth nanowires, through thermal evaporation in high vacuum at RT. Conventionally reserved for the fabrication of metal thin films, thermal evaporation deposits bismuth into an array of vertical single crystalline nanowires over a flat thin film of vanadium held at RT, which is freshly deposited by magnetron sputtering or thermal evaporation. By controlling the temperature of the growth substrate the length and width of the nanowires can be tuned over a wide range. Responsible for this novel technique is a previously unknown nanowire growth mechanism that roots in the mild porosity of the vanadium thin film. Infiltrated into the vanadium pores, the bismuth domains (~ 1 nm) carry excessive surface energy that suppresses their melting point and continuously expels them out of the vanadium matrix to form nanowires. This discovery demonstrates the feasibility of scalable vapor phase synthesis of high purity nanomaterials without using any catalysts. PMID:26709727

  14. Modeling of Thermal Phase Noise in a Solid Core Photonic Crystal Fiber-Optic Gyroscope.

    Science.gov (United States)

    Song, Ningfang; Ma, Kun; Jin, Jing; Teng, Fei; Cai, Wei

    2017-10-26

    A theoretical model of the thermal phase noise in a square-wave modulated solid core photonic crystal fiber-optic gyroscope has been established, and then verified by measurements. The results demonstrate a good agreement between theory and experiment. The contribution of the thermal phase noise to the random walk coefficient of the gyroscope is derived. A fiber coil with 2.8 km length is used in the experimental solid core photonic crystal fiber-optic gyroscope, showing a random walk coefficient of 9.25 × 10 -5 deg/√h.

  15. Bulk AlN crystal growth: self-seeding and seeding on 6H-SiC substrates

    Science.gov (United States)

    Edgar, J. H.; Liu, L.; Liu, B.; Zhuang, D.; Chaudhuri, J.; Kuball, M.; Rajasingam, S.

    2002-12-01

    The properties of bulk AlN crystals grown by sublimation recondensation and either randomly nucleated (i.e. self-seeded) or seeded on 6H-SiC substrates or compared. Self-seeding produces crystals of the highest perfection, lowest stress, and low Si and C impurity content, but the crystals grow in random crystallographic orientations. Crystals grown in boron nitride crucibles typically form thin platelets with the fastest growth occurring in the c-axis direction. Growth striations run the length of the crystals in the c-axis direction. Anisotropic etching in aqueous 45 wt% KOH solutions shows that the growth (0 0 0 1) planes exposed to the AlN source predominately have an aluminum polarity. AlN crystals seeded on 6H-SiC(0 0 0 1) have a single crystallographic orientation and the largest dimensions are perpendicular to the c-axis, determined by the size of the substrate. Cracking and voids in the AlN layer produced by differences in thermal expansion coefficients of AlN and SiC and decomposition of the SiC were ameliorated by depositing an AlN-SiC alloy layer on the SiC before growing the AlN layer. Raman spectroscopy measurements suggest the AlN and AlN-SiC alloy layer are both under tensile stress. The defect density in AlN crystals grown on composite AlN-SiC/6H-SiC substrates was 3.7×10 5 cm -2, as determined by synchrotron white beam X-ray topography.

  16. 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...

  17. Crystallization kinetics, glass transition kinetics, and thermal stability of Se70-xGa30Inx (x=5, 10, 15, and 20) semiconducting glasses

    International Nuclear Information System (INIS)

    Imran, Mousa M.A.

    2011-01-01

    Crystallization and glass transition kinetics of Se 70-x Ga 30 In x (x=5, 10, 15, and 20) semiconducting chalcogenide glasses were studied under non-isothermal condition using a Differential Scanning Calorimeter (DSC). DSC thermograms of the samples were recorded at four different heating rates 5, 10, 15, and 20 K/min. The variation of the glass transition temperature (T g ) with the heating rate (β) was used to calculate the glass transition activation energy (E t ) using two different models. Meanwhile, the variation of the peak temperature of crystallization (T p ) with β was utilized to deduce the crystallization activation energy (E c ) using Kissinger, Augis-Bennet, and Takhor models. Results reveal that E t decreases with increasing In content, while both T g and E c exhibit the opposite behavior, and the crystal growth occurs in one dimension. The variation of these thermal parameters with the average coordination number was also discussed, and the results were interpreted in terms of the type of bonding that In makes with Se. Assessment of thermal stability and glass forming ability (GFA) was carried out on the basis of some quantitative criteria and the results indicate that thermal stability is enhanced while the crystallization rate is reduced with the addition of In to Se-Ga glass. -- Research highlights: → Addition of In to Se-Ga glass decreases the glass transition activation energy. → The crystallization rate in Se-Ga-In glass is reduced as In content increases. → The crystal growth in Se-Ga-In glass occurs in one dimension. → Thermal properties of Se-Ga-In glass indicate a shift in Phillips-Thorpe threshold.

  18. Thermal, mechanical, electrical, linear and nonlinear optical properties of L-arginine dihydrofluoride single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sankar, D.; Menon, Vinay Raj; Sagayaraj, P. [Department of Physics, Loyola College, Chennai 600 034 (India); Madhavan, J., E-mail: jmadhavang@yahoo.co [Department of Physics, Loyola College, Chennai 600 034 (India)

    2010-01-01

    L-arginine dihydrofluoride of dimensions upto 15x10x9 mm{sup 3} was successfully grown by slow evaporation technique from aqueous solution. The crystal was characterized by X-ray diffractometry, Elemental analysis, FT-IR, UV-Vis-NIR spectroscopy, thermal and microhardness studies. The dielectric constant and dielectric loss of the crystal were studied as function of frequency. Photoconductivity studies were also carried out on the sample. Kurtz powder SHG measurement confirms the NLO property of the grown crystals.

  19. Single crystal cupric oxide nanowires: Length- and density-controlled growth and gas-sensing characteristics

    Science.gov (United States)

    Duc, Le Duy; Le, Dang Thi Thanh; Duy, Nguyen Van; Hoa, Nguyen Duc; Hieu, Nguyen Van

    2014-04-01

    Nanowire structured p-type CuO semiconductor is a promising material for gas-sensing applications because of its unique electrical and optical properties. In this study, we demonstrate the length and density controlled synthesis of single crystal CuO nanowires (CuO NWs) by a simple and convenient thermal oxidation of high-purity copper foils in ambient atmosphere. The density and length of the CuO NWs are controlled by varying the oxidation temperature and heating duration to investigate their growth mechanism. As-synthesized materials are characterized by different techniques, such as X-ray diffraction, field emission-scanning electron microscopy, and high-resolution transmission electron microscopy. The gas-sensing characteristics of the CuO NWs are tested using hydrogen and ethanol gases. The results show that the CuO NWs could potentially sense hydrogen and ethanol gases given a working temperature of 400 °C.

  20. 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.

  1. Thermal properties photonic crystal fiber transducers with ferromagnetic nanoparticles

    Science.gov (United States)

    Przybysz, N.; Marć, P.; Kisielewska, A.; Jaroszewicz, L. R.

    2015-12-01

    The main aim of the research is to design new types of fiber optic transducers based on filled photonic crystal fibers for sensor applications. In our research we propose to use as a filling material nanoparticles' ferrofluids (Fe3O4 NPs). Optical properties of such transducers are studied by measurements of spectral characteristics' changes when transducers are exposed to temperature and magnetic field changes. From synthesized ferrofluid several mixtures with different NPs' concentrations were prepared. Partially filled commercially available photonic crystal fiber LMA 10 (NKT Photonics) was used to design PCF transducers. Their thermo-optic properties were tested in a temperature chamber. Taking into account magnetic properties of synthetized NPs the patch cords based on a partially filled PM 1550 PCF were measured.

  2. Growth and structure of thermally evaporated Bi{sub 2}Te{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rogacheva, E.I., E-mail: rogacheva@kpi.kharkov.ua [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine); Budnik, A.V. [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine); Dobrotvorskaya, M.V.; Fedorov, A.G.; Krivonogov, S.I.; Mateychenko, P.V. [Institute for Single Crystals of NAS of Ukraine, 60 Lenin Prospect, Kharkov 61001 (Ukraine); Nashchekina, O.N.; Sipatov, A.Yu. [National Technical University “Kharkov Polytechnic Institute”, 21 Frunze St., Kharkov 61002 (Ukraine)

    2016-08-01

    The growth mechanism, microstructure, and crystal structure of the polycrystalline n-Bi{sub 2}Te{sub 3} thin films with thicknesses d = 15–350 nm, prepared by thermal evaporation in vacuum onto glass substrates, were studied. Bismuth telluride with Te excess was used as the initial material for the thin film preparation. The thin film characterization was performed using X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scan electron microscopy, and electron force microscopy. It was established that the chemical composition of the prepared films corresponded rather well to the starting material composition and the films did not contain any phases apart from Bi{sub 2}Te{sub 3}. It was shown that the grain size and the film roughness increased with increasing film thickness. The preferential growth direction changed from [00l] to [015] under increasing d. The X-ray photoelectron spectroscopy studies showed that the thickness of the oxidized surface layer did not exceed 1.5–2.0 nm and practically did not change in the process of aging at room temperature, which is in agreement with the results reported earlier for single crystals. The obtained data show that using simple and inexpensive method of thermal evaporation in vacuum and appropriate technological parameters, one can grow n-Bi{sub 2}Te{sub 3} thin films of a sufficiently high quality. - Highlights: • The polycrystalline n-Bi{sub 2}Te{sub 3} thin films were grown thermal evaporation onto glass. • The growth mechanism and film structure were studied by different structure methods. • The grain size and film roughness increased with increasing film thickness. • The growth direction changes from [00l] to [015] under film thickness increasing. • The oxidized layer thickness (1–2 nm) did not change under aging at room temperature.

  3. 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.

  4. 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)

  5. Electrical and thermal transport properties of Cr-Si alloy single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Prinsloo, A R E; Alberts, H L; Strydom, A M, E-mail: alettap@uj.ac.z [Department of Physics, University of Johannesburg, PO Box 524, Auckland Park, 2006 (South Africa)

    2010-01-01

    Electrical resistivity ({rho}), Seebeck coefficient (S) and thermal conductivity ({kappa}) measurements on Cr{sub 1-x}Si{sub x} alloy single crystals with x = 0.005, 0.012 and 0.016 reveal novel features not previously detected in polycrystalline alloys. Our results prove thermal transport to be an experimental probe that is especially well disposed towards exposing spin-density-wave ordering in an itinerant system such as Cr-Si.

  6. 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.

  7. 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.

  8. 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 ...

  9. 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 ...

  10. 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

  11. 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.

  12. 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.

  13. Non-isothermal crystallization kinetics and thermal behaviour of ...

    Indian Academy of Sciences (India)

    Administrator

    engineering applications particularly in automotive and electrical industries.5–7 A major limitation of PA is its inherently low impact strength, especially at low tempera- ture. Hence, blending of PA with elastomers has been extensively used to make them suitable for versatile engi- neering applications. The thermal property ...

  14. Synthesis, growth, optical and anisotropic mechanical behaviour of organic nonlinear optical imidazolium 2-chloro-4-nitrobenzoate single crystals

    Science.gov (United States)

    Krishnakumar, Varadharajan; Jayaprakash, Jeyaram; Boobas, Singaram; Komathi, Muniraj

    2016-10-01

    The title compound, imidazolium 2-chloro-4-nitrobenzoate (I2C4NB), has been synthesized and optical quality single crystals were grown with a dimension of 4 × 2 × 1 mm3 using an ethanol and acetone (1:1) mixed solvent by slow evaporation solution growth technique. The powder XRD analysis confirmed the crystal structure and found that it is crystallized in the non-centrosymmetric space group P21 with the monoclinic system. The symmetries of molecular vibrations were confirmed by FT-IR spectrum. The CHN(S) analysis confirmed the stoichiometric composition of the grown crystal. It also exhibits a good transparency in the entire visible region (300-800nm) and it was thermally stable up to 131.1 °C. The microhardness measurement shows the anisotropic nature of I2C4NB and also that it belongs to a soft material category. Photoconductivity studies reveal a linear increase of the photocurrent with respect to the applied electric field. HOMO LUMO studies were carried out for the crystal. The second harmonic generation test by the Kurtz powder method shows that the crystal exhibits phase matching and a conversion efficiency which is 2 times that of KDP.

  15. Bi2(Sr, Ln)2CuOz (Ln = Nd, Sm) phases: stability, crystal growth and superconducting properties

    International Nuclear Information System (INIS)

    Faqir, H.; Kikuchi, M.; Syono, Y.; Mansori, M.; Satre, P.; Sebaoun, A.; Vacquier, G.

    2000-01-01

    Bi 2 (Sr,Ln) 2 CuO z (Ln = Nd, Sm) single crystals were successfully grown by a self-flux method from stoichiometric and (Bi, Cu)-rich melts. Thermal analysis and thermogravimetry were used to determine stability and the melting sequence of Bi 2 (Sr,Ln) 2 CuO z phases in air. As-grown crystals of the ideal Bi 2 (Sr,Ln) 2 CuO z phase, of dimensions 1x0.5x0.03 mm 3 , exhibit superconducting behaviour with critical temperature T c = 21 K for the Bi 1.9 Sr 1.6 Nd 0.6 CuO z crystal and Tc = 14 K for the Bi 1.8 Sr 1.6 Sm 0.6 CuO z crystal. The compositions of these crystals were homogeneous and close to the stoichiometric composition. We report on the growth of Bi 2 Sr 2-x Sm x CuO z single crystals of large dimensions 9x3x0.03 mm 3 using Bi 2 Sr 1.5 Sm 0.5 CuO z as precursor and Bi 2 CuO 4 as flux. (author)

  16. Influence of Thermal Processing Protocol upon the Crystallization and Photovoltaic Performance of Organic–Inorganic Lead Trihalide Perovskites

    KAUST Repository

    Saliba, Michael

    2014-07-31

    We investigate the thermally induced morphological and crystalline development of methylammonium lead mixed halide perovskite (CH 3NH3PbI3-xClx) thin films and photovoltaic device performance with meso-superstructured and planar heterojunction architectures. We observe that a short rapid thermal annealing at 130 °C leads to the growth of large micron-sized textured perovskite domains and improved the short circuit currents and power conversion efficiencies up to 13.5% for the planar heterojunction perovskite solar cells. This work highlights the criticality of controlling the thin film crystallization mechanism of hybrid perovskite materials for high-performing photovoltaic applications. © 2014 American Chemical Society.

  17. 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

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

    Indian Academy of Sciences (India)

    ... Nos 32.30-r; 33.20.Ea; 42.65.Ky; 61.50.Lt; 81.70.Pg. 1. Introduction. Nonlinear optical materials generating second harmonic frequency have a significant impact on laser technology, optical communication and optical storage technology. [1,2]. High-performance electro-optic switching elements for telecommunications.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Fatigue Crack Growth in Bodies with Thermally Sprayed Coating

    Czech Academy of Sciences Publication Activity Database

    Kovářík, O.; Haušild, P.; Medřický, Jan; Tomek, L.; Siegl, J.; Mušálek, Radek; Curry, N.; Björklund, S.

    2016-01-01

    Roč. 25, 1-2 (2016), s. 311-320 ISSN 1059-9630. [ITSC 2015 : International Thermal Spray Conference and Exposition. Long Beach, California, 11.05. 2015 -14.05. 2015 ] R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : Thermal barrier coating * fatigue * crack growth * digital image correlation * digital image correlation Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.488, year: 2016 http://link.springer.com/article/10.1007%2Fs11666-015-0329-9

  4. Fatigue Crack Growth in Bodies with Thermally Sprayed Coating

    Czech Academy of Sciences Publication Activity Database

    Kovářík, O.; Haušild, P.; Medřický, Jan; Tomek, L.; Siegl, J.; Mušálek, Radek; Curry, N.; Björklund, S.

    2016-01-01

    Roč. 25, 1-2 (2016), s. 311-320 ISSN 1059-9630. [ITSC 2015: International Thermal Spray Conference and Exposition. Long Beach, California, 11.05.2015-14.05.2015] R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : Thermal barrier coating * fatigue * crack growth * digital image correlation * digital image correlation Subject RIV: JK - Corrosion ; Surface Treatment of Materials Impact factor: 1.488, year: 2016 http://link.springer.com/article/10.1007%2Fs11666-015-0329-9

  5. 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.

  6. Thermally induced phase mismatching in a repetitively Gaussian pulsed pumping KTP crystal: a spatiotemporal treatment.

    Science.gov (United States)

    Rezaee, Mostafa Mohammad; Sabaeian, Mohammad; Motazedian, Alireza; Jalil-Abadi, Fatemeh Sedaghat; Askari, Hadi; Khazrk, Iman

    2015-05-20

    Thermally induced phase mismatching (TIPM) has been proven to be an influential issue in nonlinear phenomena. It occurs when refractive indices of crystal are changed due to temperature rise. In this work, the authors report on a modeling of spatiotemporal dependence of TIPM in a repetitively pulsed pumping KTP crystal. Gaussian profiles for both spatial and temporal dependences of pump beam were used to generate second-harmonic waves in a type II configuration. This modeling is of importance in predicting the nonlinear conversion efficiency of crystals when heat is loaded in the system. To this end, at first, an approach to solve the heat equation in a repetitively pulsed pumping system with consideration of the temperature dependence of thermal conductivity and realistic cooling mechanisms such as conduction, convection, and radiation, is presented. The TIPM is then calculated through the use of experimental thermal dispersion relations of KTP crystal. The results show how accumulative behaviors of temperature and TIPM (with its reverse sign) happen when the number of pulses is increased. Fluctuations accompanying temperature and TIPM were observed which were attributed to the off-time between successive pulses. Moreover, in this work, a numerical procedure for solving a repetitively pulsed pumped crystal is introduced. This procedure enables us to solve the problem with home-used computing machines.

  7. Thermal radiation in quasiperiodic photonic crystals with negative refractive index

    International Nuclear Information System (INIS)

    Medeiros, F F de; Albuquerque, E L; Vasconcelos, M S; Mauriz, P W

    2007-01-01

    In this work we investigated the thermal power spectrum of the electromagnetic radiation through one-dimensional stacks of alternating negative and positive refractive index layers, arranged as truncated quasiperiodic photonic structures obeying the Fibonacci (FB), Thue-Morse (TM), and double-period (DP) sequences. The thermal radiation power spectra are determined by means of a theoretical model based on a transfer matrix formalism for both normal and oblique incidence geometries, together with Kirchoff's second law. We studied the radiation spectra by considering the case where both refractive indices of layers A and B are assumed to be a constant, as well as a more realistic case which takes into account the frequency-dependent electric permittivity ε and magnetic permeability μ to characterize the negative refractive index n in layer B

  8. Rare Earth Borohydrides—Crystal Structures and Thermal Properties

    Directory of Open Access Journals (Sweden)

    Christoph Frommen

    2017-12-01

    Full Text Available Rare earth (RE borohydrides have received considerable attention during the past ten years as possible hydrogen storage materials due to their relatively high gravimetric hydrogen density. This review illustrates the rich chemistry, structural diversity and thermal properties of borohydrides containing RE elements. In addition, it highlights the decomposition and rehydrogenation properties of composites containing RE-borohydrides, light-weight metal borohydrides such as LiBH4 and additives such as LiH.

  9. Thermal stability and crystallization kinetics of quaternary Sb–Se–Ge–In chalcogenide glasses

    International Nuclear Information System (INIS)

    Sharda, Sunanda; Sharma, Neha; Sharma, Pankaj; Sharma, Vineet

    2014-01-01

    Highlights: • DTA has been carried out on Sb 10 Se 65 Ge 25−y In y alloys under non-isothermal conditions at different heating rates. • E g with In content shows that probability of atoms to jump to lower metastable states increases. • The heating rate dependence of crystallization temperature shows that E c decreases. - Abstract: Thermal analysis plays an important role to know the characteristic behavior of alloys for various applications. Differential thermal analysis has been carried out on Sb 10 Se 65 Ge 25−y In y (y = 0, 3, 6, 9, 12, 15) alloys under non-isothermal conditions at different heating rates. We report the analysis of thermal parameters, viz. glass transition temperature, crystallization temperature and melting temperature. The thermal stability factor, reduced glass transition temperature, and heating rate dependence of glass transition and crystallization peaks have been investigated. The dependence of activation energies of glass transition and crystallization with In content have been discussed in terms of energy barrier and chemical bond approach respectively

  10. Thermal transport in phononic crystals: The role of zone folding effect

    Science.gov (United States)

    Dechaumphai, Edward; Chen, Renkun

    2012-04-01

    Recent experiments [Yu et al., Nature Nanotech 5, 718 (2010); Tang et al., Nano Lett. 10, 4279 (2010); Hopkins etal., Nano Lett. 11, 107(2011)] on silicon based nanoscale phononic crystals demonstrated substantially reduced thermal conductivity compared to bulk Si, which cannot be explained by incoherent phonon boundary scattering within the Boltzmann Transport Equation (BTE). In this paper, partial coherent treatment of phonons, where phonons are regarded as either wave or particles depending on their frequencies, was considered. Phonons with mean free path smaller than the characteristic size of phononic crystals are treated as particles and the transport in this regime is modeled by BTE with phonon boundary scattering taken into account. On the other hand, phonons with mean free path longer than the characteristic size are treated as waves. In this regime, phonon dispersion relations are computed using the Finite Difference Time Domain (FDTD) method and are found to be modified due to the zone folding effect. The new phonon spectra are then used to compute phonon group velocity and density of states for thermal conductivity modeling. Our partial coherent model agrees well with the recent experimental results on in-plane thermal conductivity of phononic crystals. Our study highlights the importance of zone folding effect on thermal transport in phononic crystals.

  11. 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.

  12. 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

  13. 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.

  14. OR TEP-II: a FORTRAN Thermal-Ellipsoid Plot Program for crystal structure illustrations

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, C.K.

    1976-03-01

    A computer program is described for drawing crystal structure illustrations using a mechanical plotter. Ball-and-stick type illustrations of a quality suitable for publication are produced with either spheres or thermal-motion probability ellipsoids on the atomic sites. The program can produce stereoscopic pairs of illustrations which aid in the visualization of complex packing arrangements of atoms and thermal motion patterns. Interatomic distances, bond angles, and principal axes of thermal motion are also calculated to aid the structural study. The most recent version of the program, OR TEP-II, has a hidden-line-elimination feature to omit those portions of atoms or bonds behind other atoms or bonds.

  15. Thermal properties and continuous-wave laser performance of Yb:LuVO4 crystal

    Science.gov (United States)

    Cheng, Y.; Zhang, H. J.; Yu, Y. G.; Wang, J. Y.; Tao, X. T.; Liu, J. H.; Petrov, V.; Ling, Z. C.; Xia, H. R.; Jiang, M. H.

    2007-03-01

    A laser crystal of Yb:LuVO4 with high optical quality was grown by the Czochralski technique. Its thermal properties including specific heat, thermal expansion coefficients, and thermal conductivities along the a- and c-axis have been measured for the first time. Continuous-wave laser output up to 3.5 W at 1031 nm was obtained at room temperature through end-pumping by a high-power diode laser. The corresponding optical conversion efficiency was 43% and the slope efficiency was 72%.

  16. OR TEP-II: a FORTRAN Thermal-Ellipsoid Plot Program for crystal structure illustrations

    International Nuclear Information System (INIS)

    Johnson, C.K.

    1976-03-01

    A computer program is described for drawing crystal structure illustrations using a mechanical plotter. Ball-and-stick type illustrations of a quality suitable for publication are produced with either spheres or thermal-motion probability ellipsoids on the atomic sites. The program can produce stereoscopic pairs of illustrations which aid in the visualization of complex packing arrangements of atoms and thermal motion patterns. Interatomic distances, bond angles, and principal axes of thermal motion are also calculated to aid the structural study. The most recent version of the program, OR TEP-II, has a hidden-line-elimination feature to omit those portions of atoms or bonds behind other atoms or bonds

  17. Thermal properties of borate crystals for high power optical parametric chirped-pulse amplification.

    Science.gov (United States)

    Riedel, R; Rothhardt, J; Beil, K; Gronloh, B; Klenke, A; Höppner, H; Schulz, M; Teubner, U; Kränkel, C; Limpert, J; Tünnermann, A; Prandolini, M J; Tavella, F

    2014-07-28

    The potential of borate crystals, BBO, LBO and BiBO, for high average power scaling of optical parametric chirped-pulse amplifiers is investigated. Up-to-date measurements of the absorption coefficients at 515 nm and the thermal conductivities are presented. The measured absorption coefficients are a factor of 10-100 lower than reported by the literature for BBO and LBO. For BBO, a large variation of the absorption coefficients was found between crystals from different manufacturers. The linear and nonlinear absorption coefficients at 515 nm as well as thermal conductivities were determined for the first time for BiBO. Further, different crystal cooling methods are presented. In addition, the limits to power scaling of OPCPAs are discussed.

  18. From crystal to glass-like thermal conductivity in crystalline minerals.

    Science.gov (United States)

    Bouyrie, Y; Candolfi, C; Pailhès, S; Koza, M M; Malaman, B; Dauscher, A; Tobola, J; Boisron, O; Saviot, L; Lenoir, B

    2015-08-14

    The ability of some materials with a perfectly ordered crystal structure to mimic the heat conduction of amorphous solids is a remarkable physical property that finds applications in numerous areas of materials science, for example, in the search for more efficient thermoelectric materials that enable to directly convert heat into electricity. Here, we unveil the mechanism in which glass-like thermal conductivity emerges in tetrahedrites, a family of natural minerals extensively studied in geology and, more recently, in thermoelectricity. By investigating the lattice dynamics of two tetrahedrites of very close compositions (Cu12Sb2Te2S13 and Cu10Te4S13) but with opposite glasslike and crystal thermal transport by means of powder and single-crystal inelastic neutron scattering, we demonstrate that the former originates from the peculiar chemical environment of the copper atoms giving rise to a strongly anharmonic excess of vibrational states.

  19. Nonlinear continuous-wave optical propagation in nematic liquid crystals: Interplay between reorientational and thermal effects.

    Science.gov (United States)

    Alberucci, Alessandro; Laudyn, Urszula A; Piccardi, Armando; Kwasny, Michał; Klus, Bartlomiej; Karpierz, Mirosław A; Assanto, Gaetano

    2017-07-01

    We investigate nonlinear optical propagation of continuous-wave (CW) beams in bulk nematic liquid crystals. We thoroughly analyze the competing roles of reorientational and thermal nonlinearity with reference to self-focusing/defocusing and, eventually, the formation of nonlinear diffraction-free wavepackets, the so-called spatial optical solitons. To this extent we refer to dye-doped nematic liquid crystals in planar cells excited by a single CW beam in the highly nonlocal limit. To adjust the relative weight between the two nonlinear responses, we employ two distinct wavelengths, inside and outside the absorption band of the dye, respectively. Different concentrations of the dye are considered in order to enhance the thermal effect. The theoretical analysis is complemented by numerical simulations in the highly nonlocal approximation based on a semi-analytic approach. Theoretical results are finally compared to experimental results in the Nematic Liquid Crystals (NLC) 4-trans-4'-n-hexylcyclohexylisothiocyanatobenzene (6CHBT) doped with Sudan Blue dye.

  20. 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.

  1. 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.

  2. Growth and characterization of L-alanine cadmium bromide a semiorganic nonlinear optical crystals.

    Science.gov (United States)

    Ilayabarathi, P; Chandrasekaran, J

    2012-10-01

    A new semiorganic nonlinear optical crystal, l-alanine cadmium bromide (LACB) was grown from aqueous solution by slow solvent evaporation method at room temperature. As grown crystals were characterized for its spectral, thermal, linear and second order nonlinear optical properties. LACB crystallizes in orthorhombic system and unit cell parameters a=5.771(2)Å, b=6.014(4)Å, c=12.298(2)Å, α=β=γ=90° and volume=426.8(3)Å(3). The mode of vibrations of different molecular groups present in the crystal was identified by FTIR study. The grown crystals were found to be transparent in the entire visible region. The thermal strength and the decomposition of the grown crystals were studied using TG/DTA and DSC analysis. Dielectric measurement revealed that the crystals had very low dielectric constant at higher frequency in room temperature. The mechanical behavior was studied by Vicker's microhardness tester. The grown crystal has negative photoconductivity nature. The fluorescence spectrum of the crystal was recorded and its optical band gap is about 3.356 eV. The NLO property of crystal using modified Kurtz-Perry powder technique with Nd:YAG laser light of wavelength 1064nm indicated that their second harmonic generation (SHG) efficiency was half that of pure KDP. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Application of ZnO single-crystal wire grown by the thermal evaporation method as a chemical gas sensor for hydrogen sulfide.

    Science.gov (United States)

    Park, N K; Lee, S Y; Lee, T J

    2011-01-01

    A zinc oxide single-crystal wire was synthesized for application as a gas-sensing material for hydrogen sulfide, and its gas-sensing properties were investigated in this study. The gas sensor consisted of a ZnO thin film as the buffer layer and a ZnO single-crystal wire. The ZnO thin film was deposited over a patterning silicon substrate with a gold electrode by the CFR method. The ZnO single-crystal wire was synthesized over the ZnO thin film using zinc and activated carbon as the precursor for the thermal evaporation method at 800 degrees C. The electrical properties of the gas sensors that were prepared for the growth of ZnO single-crystal wire varied with the amount of zinc contained in the precursor. The charged current on the gas sensors increased with the increasing amount of zinc in the precursor. It was concluded that the charged current on the gas sensors was related to ZnO single-crystal wire growth on the silicon substrate area between the two electrodes. The charged current on the gas sensor was enhanced when the ZnO single-crystal wire was exposed to a H2S stream. The experimental results obtained in this study confirmed that a ZnO single-crystal wire can be used as a gas sensor for H2S.

  4. Blocking rapid ice crystal growth through nonbasal plane adsorption of antifreeze proteins.

    Science.gov (United States)

    Olijve, Luuk L C; Meister, Konrad; DeVries, Arthur L; Duman, John G; Guo, Shuaiqi; Bakker, Huib J; Voets, Ilja K

    2016-04-05

    Antifreeze proteins (AFPs) are a unique class of proteins that bind to growing ice crystal surfaces and arrest further ice growth. AFPs have gained a large interest for their use in antifreeze formulations for water-based materials, such as foods, waterborne paints, and organ transplants. Instead of commonly used colligative antifreezes such as salts and alcohols, the advantage of using AFPs as an additive is that they do not alter the physicochemical properties of the water-based material. Here, we report the first comprehensive evaluation of thermal hysteresis (TH) and ice recrystallization inhibition (IRI) activity of all major classes of AFPs using cryoscopy, sonocrystallization, and recrystallization assays. The results show that TH activities determined by cryoscopy and sonocrystallization differ markedly, and that TH and IRI activities are not correlated. The absence of a distinct correlation in antifreeze activity points to a mechanistic difference in ice growth inhibition by the different classes of AFPs: blocking fast ice growth requires rapid nonbasal plane adsorption, whereas basal plane adsorption is only relevant at long annealing times and at small undercooling. These findings clearly demonstrate that biomimetic analogs of antifreeze (glyco)proteins should be tailored to the specific requirements of the targeted application.

  5. 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.

  6. Geometric tuning of thermal conductivity in three-dimensional anisotropic phononic crystals.

    Science.gov (United States)

    Wei, Zhiyong; Wehmeyer, Geoff; Dames, Chris; Chen, Yunfei

    2016-10-07

    Molecular dynamics simulations are performed to investigate the thermal transport properties of a three-dimensional (3D) anisotropic phononic crystal consisting of silicon nanowires and films. The calculation shows that the in-plane thermal conductivity is negatively correlated with the out-of-plane thermal conductivity upon making geometric changes, whether varying the nanowire diameter or the film thickness. This enables the anisotropy ratio of thermal conductivity to be tailored over a wide range, in some cases by more than a factor of 20. Similar trends in thermal conductivity are also observed from an independent phonon ray tracing simulation considering only diffuse boundary scattering effects, though the range of anisotropy ratios is smaller than that obtained in MD simulation. By analyzing the phonon dispersion relation with varied geometric parameters, it is found that increasing the nanowire diameter increases the out-of-plane acoustic phonon group velocities, but reduces the in-plane longitudinal and fast transverse acoustic phonon group velocities. The calculated phonon irradiation further verified the negative correlation between the in-plane and the out-of-plane thermal conductivity. The proposed 3D phononic crystal may find potential application in thermoelectrics, energy storage, catalysis and sensing applications owing to its widely tailorable thermal conductivity.

  7. Effect of the packing structure of silicon chunks on the melting process and carbon reduction in Czochralski silicon crystal growth

    Science.gov (United States)

    Liu, Xin; Nakano, Satoshi; Kakimoto, Koichi

    2017-06-01

    Carbon (C) contamination in Czochralski silicon (CZ-Si) crystal growth mainly originates from carbon monoxide (CO) generation on the graphite components, which reaches a maximum during the melting stage. Loading a crucible with poly-Si feedstock includes many technical details for optimization of the melting and growth processes. To investigate the effect of the packing structure of Si chunks on C accumulation in CZ-Si crystal growth, transient global simulations of heat and mass transport were performed for the melting process with different packing structures of poly-Si. The heat transport modeling took into account the effective thermal conductivity (ETC) of the Si feedstock, which is affected by the packing structure. The effect of the chunk size on the melting process and C accumulation were investigated by parametric studies of different packing structures. The heat transport and melting process in the crucible were affected by the ETC and the emissivity of the Si feedstock. It was found that smaller Si chunks packed in the upper part could speed up the melting process and smooth the power profile. Decreasing the duration of the melting process is favorable for reduction of C contamination in the Si feedstock. Parametric studies indicated that optimization of the melting process by the packing structure is possible and essential for C reduction in CZ-Si crystal growth.

  8. 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.

  9. Measurements of Thermal Conductivity and Thermal Diffusivity of Hen Egg-White Lysozyme Crystals and Its Solution Using the Transient Short Hot Wire Method

    Science.gov (United States)

    Fujiwara, Seiji; Maki, Syou; Maekawa, Ryunosuke; Tanaka, Seiichi; Hagiwara, Masayuki

    2017-08-01

    Protein crystals are an essentially important biological sample to advance the analysis of X-ray structure, but their thermophysical properties, especially thermal conductivity and thermal diffusivity, have not been studied sufficiently. This current situation can be attributed to various kinds of technical problems; e.g., the fragility of protein crystals and the difficulty of nucleation control. Ideally speaking, protein crystallization should be carried out under a " containerless condition" to eliminate any mechanical distortion of the crystals from the walls. To realize the condition, we have developed an original crystallization method by means of the magneto-Archimedes effect. In this paper, a transient short hot wire method was combined with the technique of magneto-Archimedes effect to realize simultaneous measurement of thermal conductivity and thermal diffusivity of hen egg-white lysozyme (HEWL) crystals. As the results, thermal conductivity and thermal diffusivity of HEWL crystals were found to be 0.410-0.438 \\hbox {W}\\cdot \\hbox {m}^{-1}\\cdot \\hbox {K}^{-1} and 3.77-5.18× 10^{-8} \\hbox {m}2\\cdot \\hbox {s}^{-1}, respectively. We clarified by the crystallizing process of HEWL that the crystals were magnetically levitated at the air-liquid interface and the short hot wire was completely buried into them as the crystals grew. We also measured the HEWL solution by the same methods. The thermal conductivity of the solution had almost the same value as that of water and had little dependency on the concentration of HEWL, but the thermal diffusivity was unclear.

  10. Crack growth resistance under thermal shock loading of alumina

    Energy Technology Data Exchange (ETDEWEB)

    Saadaoui, M. [Ecole Mohammadia d`Ingenieurs (EMIL), Rabat (Morocco); Fantozzi, G. [GEMPPM-UMR CNRS 5510, INSA Lyon, Villeurbanne (France)

    1998-06-01

    Thermal shock experiments, conducted in an apparatus in which all the parameters can be controlled, are modelled by a two dimensional cooling model, allowing a precise determination of the induced stress intensity factors (SIF). Fracture mechanics analysis in terms of stress intensity factors is applied to determine R-curve behaviour of indentation cracks in alumina materials subjected to thermal shock. The instant of unstable crack growth was obtained by acoustic emission (AE). As in bending tests, the coarse grained material showed a more pronounced R-curve behaviour than the fine grained material. The results are discussed considering the influence of the R-curve behaviour on the retained strength after thermal shock. (orig.) 25 refs.

  11. Interface dynamics and domain growth in thermally bistable fluids

    International Nuclear Information System (INIS)

    Shaviv, N.J.; Regev, O.

    1994-01-01

    Domain growth kinetics in a thermally bistable fluid with heat diffusion is studied. The time evolution of interfaces between the stable phases is calculated numerically in two dimensions and compared to some general results derived analytically. The qualitative behavior is found to be similar to the previously studied cases where fluid dynamics was neglected. There are, however, several important differences such as the value of the dynamical exponent, which determines the power law of the system's correlation length growth. The introduction of fluid motion into the model introduces additional properties, unfamiliar to previously studied systems, like the change of the pressure or the size of the system. This behavior is due to the advection of mass. The present model may have general relevance to any system modeled by a real Ginzburg-Landau-type equation coupled to fluid dynamical conservation equations. In particular, it is a step forward on the way to a faithful modeling of thermally bistable cloudy astrophysical media

  12. Crystallization, structural relaxation and thermal degradation in Poly(L-lactide)/cellulose nanocrystal renewable nanocomposites.

    Science.gov (United States)

    Lizundia, E; Vilas, J L; León, L M

    2015-06-05

    In this work, crystallization, structural relaxation and thermal degradation kinetics of neat Poly(L-lactide) (PLLA) and its nanocomposites with cellulose nanocrystals (CNC) and CNC-grafted-PLLA (CNC-g-PLLA) have been studied. Although crystallinity degree of nanocomposites remains similar to that of neat homopolymer, results reveal an increase on the crystallization rate by 1.7-5 times boosted by CNC, which act as nucleating agents during the crystallization process. In addition, structural relaxation kinetics of PLLA chains has been drastically reduced by 53% and 27% with the addition of neat and grafted CNC, respectively. The thermal degradation activation energy (E) has been determined from thermogravimetric analysis in the light of Kissinger's and Ozawa-Flynn-Wall theoretical models. Results reveal a reduction on the thermal stability when in presence of CNC-g-PLLA, while raw CNC slightly increases the thermal stability of PLLA. Fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy results confirm that the presence of residual catalyst in CNC-g-PLLA plays a pivotal role in the thermal degradation behavior of nanocomposites. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Formation and growth of crystal defects in directionally solidified multicrystalline silicon for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ryningen, Birgit

    2008-07-01

    crucible bottom and the subsequent growth is governed by dislocations. For the other type of ingots which is dominated by twins and has a higher minority carrier lifetime, a higher undercooling has occurred before crystal nucleation. It is suggested that this undercooling can reach the critical value for dendritic nucleation to occur (10 K). After dendritic nucleation, subsequent crystal growth is dominated by twins. Nucleation and multiplication mechanisms for dislocations are complex, and investigations on a microscopic scale have been performed. Mechanisms such as punch-out from precipitates with a thermal expansion coefficient different from that of the silicon matrix, intergranular - and intragranular hardening and development of strain fields due to differences in the elasticity module between different grains are thought to play a role in the nucleation of dislocations higher up in the cast. The multiplication has been explained by a macroscopic stress field at the solidification front, stresses developed during cooling and pinning by oxygen impurities. For dislocations nucleated by an angular grain boundary a multiplication and growth mechanism is proposed where dislocations can cross slip and line up at certain crystallographic directions during crystal growth. (Author). 134 refs., 29 figs., 4 tabs

  14. Thermalization calorimetry: A simple method for investigating glass transition and crystallization of supercooled liquids

    Directory of Open Access Journals (Sweden)

    Bo Jakobsen

    2016-05-01

    Full Text Available We present a simple method for fast and cheap thermal analysis on supercooled glass-forming liquids. This “Thermalization Calorimetry” technique is based on monitoring the temperature and its rate of change during heating or cooling of a sample for which the thermal power input comes from heat conduction through an insulating material, i.e., is proportional to the temperature difference between sample and surroundings. The monitored signal reflects the sample’s specific heat and is sensitive to exo- and endothermic processes. The technique is useful for studying supercooled liquids and their crystallization, e.g., for locating the glass transition and melting point(s, as well as for investigating the stability against crystallization and estimating the relative change in specific heat between the solid and liquid phases at the glass transition.

  15. Thermal oxidative degradation behaviours of flame-retardant thermotropic liquid crystal copolyester/PET blends

    International Nuclear Information System (INIS)

    Du Xiaohua; Zhao Chengshou; Wang Yuzhong; Zhou Qian; Deng Yi; Qu Minghai; Yang Bing

    2006-01-01

    The flame retardancy and the thermal oxidative degradation behaviors of the blend of poly(ethylene terephthalate) (PET) with a kind of phosphorus-containing thermotropic liquid crystal copolyester (TLCP) with high flame retardancy (limited oxygen index, 70%) have been investigated by oxygen index test (LOI), UL-94 rating and thermogravimetric analysis (TGA) in air. The results show that TLCP can dramatically improve the flame retardancy and the melt dripping behavior of PET. Moreover, the apparent activation energies of thermal oxidative degradation of the blends were evaluated using Kissinger and Flynn-Wall-Ozawa methods. It is found that addition of TLCP improve thermal stability and restrain thermal decomposition of PET in air, especially at the primary degradation stage. Py-GC/MS analysis shows that there are remarkable changes in the pyrolysis products when TLCP are blended into PET. The interaction between TLCP and PET has changed their thermal oxidative degradation mechanism

  16. Crystal plasticity extend FEM implementation of thermal-tensile aluminum alloy

    Directory of Open Access Journals (Sweden)

    Liu Yang

    2016-01-01

    Full Text Available Multi-level approach has been used to simulate the thermal deformation of aluminium alloy at different temperature and strain rate. The crystal plasticity model is extended in the finite element method and the thermal behaviour is integrated in the constitutive equations. Moreover, the damage evolution is also reflected in the simulation using continuum damage mechanics model. Thus, the void evolution and thermal effect could both be shown in the simulation. A new shear strain rate model is constructed with the thermal activated mechanism to describe the rate dependent behaviours during tensile test. The thermal parameters are determined in a fitting test of representative volume element to compare with the experimental data. The results prove that the mechanical tensile behaviour of 5052 aluminium alloy could be well described at different temperatures. The damage evolution process is expressed by the stress concentration and strain concentration in the finite element simulation, which are also confirmed by the experiments.

  17. 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.

  18. Thermally reversible single-crystal to single-crystal transformation of mononuclear to dinuclear Zn(II) complexes by [2+2] cycloaddition reaction.

    Science.gov (United States)

    Medishetty, Raghavender; Yap, Terence Teck Sheng; Koh, Lip Lin; Vittal, Jagadese J

    2013-10-25

    Two Zn(II) complexes of trans-4-styrylpyridine ligands undergo [2+2] cycloaddition reaction forming Zn(II) complex dimers in a single-crystal to single-crystal (SCSC) manner which were thermally reversible. The dimers are presumed to be the stable intermediates in the formation of 1D coordination polymers upon prolonged exposure to UV light.

  19. Thermal optical nonlinearity in photonic crystal fibers filled with nematic liquid crystals doped with gold nanoparticles

    Science.gov (United States)

    Lesiak, Piotr; Budaszewski, Daniel; Bednarska, Karolina; Wójcik, Michał; Sobotka, Piotr; Chychłowski, Miłosz; Woliński, Tomasz R.

    2017-05-01

    In this work we studied a newly reported class of nonlinear effects observed in 5CB liquid crystals doped with gold nanoparticles (GNPs). The size of the GNP was determined by direct TEM imaging and by X-ray scattering of the diluted NP solution. GNPs was coated by thiols with the ratio of mesogenic to n-alkyl thiols varying from 1:2 to 1:1. The research involved comparing properties of both undoped and doped 5CB (nematic LC) by infiltrating LC cell and microholes of the photonic crystal fiber (PCF) separately. In our experiment the PCF fiber type LMA-10 made by NKT Photonics as host material has been used.

  20. 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.

  1. 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.

  2. 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.

  3. Experimental determination of phonon thermal conductivity and Lorenz ratio of single crystal metals: Al, Cu and Zn

    OpenAIRE

    Yao, Mengliang; Zebarjadi, Mona; Opeil, Cyril P.

    2017-01-01

    We use a magnetothermal resistance method to measure lattice thermal conductivity of pure single crystal metals over a wide range of temperatures. Large transverse magnetic fields are applied to suppress electronic thermal conduction. The total thermal conductivity and the electrical conductivity are measured as functions of applied magnetic field. The lattice thermal conductivity is then extracted by extrapolating the thermal conductivity versus electrical conductivity curve at zero electric...

  4. 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

  5. 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 ...

  6. 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

  7. 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 ...

  8. 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.

  9. Structural, thermal and optical characterization of an organic NLO material—Benzaldehyde thiosemicarbazone monohydrate single crystals

    Science.gov (United States)

    Santhakumari, R.; Ramamurthi, K.

    2011-02-01

    Single crystals of the organic NLO material, benzaldehyde thiosemicarbazone (BTSC) monohydrate, were grown by slow evaporation method. Solubility of BTSC monohydrate was determined in ethanol at different temperatures. The grown crystals were characterized by single crystal X-ray diffraction analysis to determine the cell parameters and by FT-IR technique to study the presence of the functional groups. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. UV-vis-NIR spectrum shows excellent transmission in the region of 200-1100 nm. Theoretical calculations were carried out to determine the linear optical constants such as extinction coefficient and refractive index. Further the optical nonlinearities of BTSC have been investigated by Z-scan technique with He-Ne laser radiation of wavelength 632.8 nm. Mechanical properties of the grown crystal were studied using Vickers microhardness tester. Second harmonic generation efficiency of the powdered BTSC monohydrate was tested using Nd:YAG laser and it is found to be ˜5.3 times that of potassium dihydrogen orthophosphate.

  10. 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.

  11. 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.

  12. Crystal-Growing Crucible To Suppress Convection

    Science.gov (United States)

    Richter, R.

    1986-01-01

    Platform under growth region stabilizes melt for more uniform crystal growth. In new crucible, platform just below growth interface so melt is too shallow to support convection. Critical depth for onset of pertinent instability calculated from heat flux through surface of melt, volume coefficient of thermal expansion, thermal conductivity, thermal diffusivity, and kinematic viscosity.

  13. ANSYS program and re-validation of the thermal analysis of the Cornell silicon crystal

    International Nuclear Information System (INIS)

    Khounsary, A.; Kuzay, T.

    1992-01-01

    Thermal analysis of the Cornell three-channel silicon crystal is carried out using the ANSYS finite element program. Results are in general agreement with those previously obtained using the Transient Heat Transfer, version B (THTB) program. The main thrust of the present study has been to (a) explore the thermal analysis potentials of the ANSYS program in solving thermal hydraulic problems in the APS beamline design, (b) compare the ANSYS results with those obtained by THTB for a specific test crystal, and (c) obtain some cost benchmarks for the ANSYS program. On the basis of a limited number of test runs for the silicon crystal problem, conclusions can be drawn that (a) except for conduction problems with simple boundary conditions the utility of ANSYS for solving a variety of three-dimensional thermal hydraulic problems is at best limited, (b) in comparison with THTB program, ANSYS requires a more detailed modeling (with increasing computation time) for comparably accurate results, and (c) no firm statement regarding the cost factor can be made at this time although the ANSYS program appears to be more expensive than any other code we have used so far

  14. 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.

  15. Thermally enhanced optical nonlinearity in nematic liquid crystal close to phase transition temperature

    Science.gov (United States)

    Shih, Chia-Chi; Chen, Yu-Jen; Hung, Wen-Chi; Jiang, I.-Min; Tsai, Ming-Shan

    2010-09-01

    This study investigates the beam profile and the liquid crystal (LC) arrangement affected by an optical field on LC thin films at a temperature close to nematic-isotropic phase transition temperature ( TNI). A combined microscopic and conoscopic technique was used in experiments as a convenient way to analyze the optical nonlinearity that is associated with the molecular configuration of nematic liquid crystal (NLC). An optical field combined with thermal enhancement enhances molecular reorientation and causes additional molecular excitation along the axis of propagation of the beam. The reorientational nonlinearity yields an undulating structure with multi-foci; the length between each pair of foci increases with time, as described.

  16. 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.

  17. 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...

  18. 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

  19. 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 ...

  20. Calculation of thermal deformations in water-cooled monochromator crystals

    International Nuclear Information System (INIS)

    Nakamura, Ario; Hashimoto, Shinya; Motohashi, Haruhiko

    1994-11-01

    Through calculation of temperature distribution and thermal deformation of monochromators, optical degradation by the heat loads in SPring-8 have been discussed. Cooling experiments were made on three models of copper structures with the JAERI Electron Beam Irradiation Stand (JEBIS) and the results were used to estimate heat transfer coefficients in the models. The heat transfer coefficients have been adopted to simulate heating processes on silicon models of the same structures as the copper models, for which radiations from the SPring-8 bending magnet and the JAERI prototype undulator (WPH-33J) were considered. It has been concluded that, in the case of bending magnet (with power density of 0.27[MW/m 2 ] on monochromator surface), the temperature at the surface center reaches about 30[degC] from the initial temperature of 27[degC] in all the models. In the case of WPH-33J (with power density of 8.2[MW/m 2 ]), the temperature reaches about 200 to 280[degC] depending on the models. The radiation from WPH-33J yields slope errors bigger than the Darwin's width(23[μrad]). (author)

  1. 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

  2. Calorimetric determination of inhibition of ice crystal growth by antifreeze protein in hydroxyethyl starch solutions.

    Science.gov (United States)

    Hansen, T N; Carpenter, J F

    1993-01-01

    Differential scanning calorimetry and cryomicroscopy were used to investigate the effects of type I antifreeze protein (AFP) from winter flounder on 58% solutions of hydroxyethyl starch. The glass, devitrification, and melt transitions noted during rewarming were unaffected by 100 micrograms/ml AFP. Isothermal annealing experiments were undertaken to detect the effects of AFP-induced inhibition of ice crystal growth using calorimetry. A premelt endothermic peak was detected during warming after the annealing procedure. Increasing the duration or the temperature of the annealing for the temperature range from -28 and -18 degrees C resulted in a gradual increase in the enthalpy of the premelt endotherm. This transition was unaffected by 100 micrograms/ml AFP. Annealing between -18 and -10 degrees C resulted in a gradual decrease in the premelt peak enthalpy. This process was inhibited by 100 micrograms/ml AFP. Cryomicroscopic examination of the samples revealed that AFP inhibited ice recrystallization during isothermal annealing at -10 degrees C. Annealing at lower temperatures resulted in minimal ice recrystallization and no visible effect of AFP. Thus, the 100 micrograms/ml AFP to have a detectable influence on thermal events in the calorimeter, conditions must be used that result in significant ice growth without AFP and visible inhibition of this process by AFP. Images FIGURE 8 PMID:7690257

  3. Fast crystallization of amorphous Gd2Zr2O7 induced by thermally activated electron-beam irradiation

    Science.gov (United States)

    Huang, Zhangyi; Qi, Jianqi; Zhou, Li; Feng, Zhao; Yu, Xiaohe; Gong, Yichao; Yang, Mao; Shi, Qiwu; Wei, Nian; Lu, Tiecheng

    2015-12-01

    We investigate the ionization and displacement effects of an electron-beam (e-beam) on amorphous Gd2Zr2O7 synthesized by the co-precipitation and calcination methods. The as-received amorphous specimens were irradiated under electron beams at different energies (80 keV, 120 keV, and 2 MeV) and then characterized by X-ray diffraction and transmission electron microscopy. A metastable fluorite phase was observed in nanocrystalline Gd2Zr2O7 and is proposed to arise from the relatively lower surface and interface energy compared with the pyrochlore phase. Fast crystallization could be induced by 120 keV e-beam irradiation (beam current = 0.47 mA/cm2). The crystallization occurred on the nanoscale upon ionization irradiation at 400 °C after a dose of less than 1017 electrons/cm2. Under e-beam irradiation, the activation energy for the grain growth process was approximately 10 kJ/mol, but the activation energy was 135 kJ/mol by calcination in a furnace. The thermally activated ionization process was considered the fast crystallization mechanism.

  4. Thermal pre-treated effect on the thermoluminescent response of NaCl: Eu crystals

    International Nuclear Information System (INIS)

    Mondragon G, G.; Mendoza A, D.; Gonzalez, P.R.; Nicho D, M.E.; Reyes G, J.

    2007-01-01

    Full text: A thermoluminescent (TL) study with ultraviolet (UV) radiation in Czochralski-grew NaCl:Eu crystals previously thermal treated at 100, 200, 300, 400, 500 and 600 C for 2h in an inert atmosphere is presented. According to the results obtained, all samples thermal treated showed an important TL signal, however the intensity and the glow curve shape was different depending of the treatment temperature. The sample thermal treated at 300 showed a highest sensitivity with four TL peaks at 85, 109, 139 and 193 C, while the sample thermal treated at 500 showed a lowest sensitivity with three TL-peaks at 84, 106 and 201 C. This study was- complemented with an analysis of the fading behavior to evaluate the possibility to use this kind of material as dosimeter of ultraviolet radiation. (Author)

  5. Straightforward measurement of anisotropic thermal properties of a Bi2Se3 single crystal.

    Science.gov (United States)

    Fournier, Danièle; Marangolo, Massimiliano; Eddrief, Mahmoud; Kolesnikov, Nicolai N; Fretigny, Christian

    2018-02-06

    We demonstrate here a simple measurement protocol which allows the thermal properties of anisotropic crystalline materials to be determined. This protocol is validated by the measurement of Bi2Se3, a layered material consisting of covalently bonded sheets with weak van-der-Waals bonds between each layer, which has highly anisotropic thermal properties. Thermoreflectance microscopy measurements were carried out on a single-crystal Bi2Se3 sample, firstly on the bare sample and then after capping wih a 100 nm thick gold layer. Whereas on the bare sample lateral heat diffusion is dominated by the in-plane thermal diffusivity, on the metal-capped substrate heat diffusion perpendicular to the sample surface dominates. Using a simple theoretical model, we show how this double measurement protocol allows the anisotropic thermal conductivity coefficients of bulk Bi2Se3 to be evaluated. © 2018 IOP Publishing Ltd.

  6. 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

  7. 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-.

  8. Investigation of SR method grown <0 0 1> directed KDP single crystal and its characterization by high-resolution X-ray diffractometry (HRXRD), laser damage threshold, dielectric, thermal analysis, optical and hardness studies

    Energy Technology Data Exchange (ETDEWEB)

    Balamurugan, S. [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam, Chennai 603 110 (India); Ramasamy, P., E-mail: ramasamyp@ssn.edu.in [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam, Chennai 603 110 (India); Sharma, S.K. [LMDDD, RRCAT, Indore (India); Inkong, Yutthapong; Manyum, Prapun [School of Physics, Institute of Science, Suranaree University of Technology (Thailand)

    2009-10-15

    <0 0 1> directed potassium dihydrogen orthophosphate (KDP) single crystal was grown by Sankaranarayanan-Ramasamy (SR) method. The <0 0 1> oriented seed crystals were mounted at the bottom of the platform and the size of the crystals were 10 mm diameter, 110 mm height. Two different growths were tried, in one the crystal diameter was the ampoule's inner diameter and in the other the crystal thickness was less than the ampoule diameter. In the first case only the top four pyramidal faces were existing whereas in the second case the top four pyramidal faces and four prismatic faces were existing through out the growth. The crystals were grown using same stoichiometric solution. The results of the two growths are discussed in this paper. The grown crystals were characterized by high-resolution X-ray diffractometry (HRXRD), laser damage threshold, dielectric, thermal analysis, UV-vis spectroscopy and microhardness studies. The HRXRD analysis indicates that the crystalline perfection is excellent without having any very low angle internal structural grain boundaries. Laser damage threshold value has been determined using Nd:glass laser operating at 1054 nm. The damage threshold for the KDP crystal is greater than 4.55 GW cm{sup -2}. The dielectric constant was higher and the dielectric loss was less in SR method grown crystal as against conventional method grown crystal. In thermal analysis, the starting of decomposition nature is similar in SR method grown KDP crystal and conventional method grown crystal. The SR method grown KDP has higher transmittance and higher hardness value compared to conventional method grown crystals.

  9. Growth and properties of semi-organic nonlinear optical crystal: L-Glutamic acid hydrochloride

    Directory of Open Access Journals (Sweden)

    J. Uma

    2016-02-01

    Full Text Available Semiorganic nonlinear optical crystal of L-Glutamic acid hydrochloride (LGHC was grown from aqueous solution by slow evaporation technique. Single crystal X-ray Diffraction analysis confirms that LGHC crystallizes in orthorhombic system with noncentrosymmetric space group P212121. The powder X-ray diffraction study confirms the crystallinity of the grown crystal. The fundamental functional groups of the grown crystals were analyzed by Fourier Transform Infrared spectroscopic analysis in the range of 450–4000 cm−1. The range of optical transmission was ascertained using UV–vis–NIR studies. The Refractive Index of the LGHC crystal was found to be 1.4. The second harmonic generation efficiency of the LGHC was determined using Kurtz and Perry powder technique and it was 0.5 times greater than that of the KDP crystal. Thermo Gravimetric Analysis (TGA and Differential Thermal Analysis (DTA were used to study thermal behavior of the sample. The dielectric behavior and ac conductivity of the sample were studied as a function of frequency for different temperatures. The mechanical strength of the crystal was determined by Vicker׳s Hardness test. The elastic stiffness constant and yield strength of the sample was calculated.

  10. 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%

  11. 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%.

  12. 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%.

  13. High-temperature Raman study of L-alanine, L-threonine and taurine crystals related to thermal decomposition

    International Nuclear Information System (INIS)

    Cavaignac, A.L.O.; Lima, R.J.C.; Façanha Filho, P.F.; Moreno, A.J.D.; Freire, P.T.C.

    2016-01-01

    In this work high-temperature Raman spectra are used to compare temperature dependence of the lattice mode wavenumber of L-alanine, L-threonine and taurine crystals. Anharmonic effects observed are associated with intermolecular N-H· · ·O hydrogen bond that plays an important role in thermal decomposition process of these materials. Short and strong hydrogen bonds in L-alanine crystal were associated with anharmonic effects in lattice modes leading to low thermal stability compared to taurine crystals. Connection between thermal decomposition process and anharmonic effects is furnished for the first time.

  14. High-temperature Raman study of L-alanine, L-threonine and taurine crystals related to thermal decomposition

    Science.gov (United States)

    Cavaignac, A. L. O.; Lima, R. J. C.; Façanha Filho, P. F.; Moreno, A. J. D.; Freire, P. T. C.

    2016-03-01

    In this work high-temperature Raman spectra are used to compare temperature dependence of the lattice mode wavenumber of L-alanine, L-threonine and taurine crystals. Anharmonic effects observed are associated with intermolecular N-H· · ·O hydrogen bond that plays an important role in thermal decomposition process of these materials. Short and strong hydrogen bonds in L-alanine crystal were associated with anharmonic effects in lattice modes leading to low thermal stability compared to taurine crystals. Connection between thermal decomposition process and anharmonic effects is furnished for the first time.

  15. Growth, optical, thermal and dielectric studies of an amino acid organic nonlinear optical material: L-Alanine

    International Nuclear Information System (INIS)

    Caroline, M. Lydia; Sankar, R.; Indirani, R.M.; Vasudevan, S.

    2009-01-01

    Good transparent bulk single crystals of L-alanine (nonlinear optical material) have been grown successfully by slow cooling technique from aqueous solution at pH value of 2.0. Optically transparent crystals with dimensions 2.4 cm x 1.2 cm x 1.6 cm, were grown by optimizing the growth parameters within a growth period of 2 weeks. The crystallinity of L-alanine crystal was confirmed by the powder X-ray diffraction study and diffraction peaks are indexed. The vibrational structure of the molecule is elucidated from FTIR spectra. The thermal behaviour of the grown crystal was investigated by thermogravimetric (TG) and differential thermal analyses (DTA) techniques in a nitrogen atmosphere. The result showed that the material starts decomposing at 297 deg. C. Its optical behaviour has been examined by UV-vis spectral analysis, which shows the absence of absorbance between the wavelengths ranging from 200 to 1200 nm. The NLO property was confirmed by the powder technique of Kurtz and Perry. The dielectric behaviour of the sample was also studied for the first time

  16. 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.

  17. 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.

  18. Microstructure and thermal change of texture of calcite crystals in ostrich eggshell Struthio camelus

    International Nuclear Information System (INIS)

    Heredia, A.; Rodriguez-Hernandez, A.G.; Lozano, L.F.; Pena-Rico, M.A.; Velazquez, R.; Basiuk, V.A.; Bucio, L.

    2005-01-01

    Eggshell from ostrich Struthio camelus, pristine and thermally treated in the range from room temperature to 550 deg. C, was investigated with low vacuum scanning electron microscopy (LVSEM), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and X-ray powder diffractometry (XRD). Different zones of the eggshell were analysed, including the protein-related, non-crystalline, inner organic membrane. After the high-temperature treatment (>500 deg. C), only crystallised calcite phase was found showing two main textures depending on the shell zone and the treatment temperature. In the crystal layer of the untreated samples, nanosized calcite crystals are organized with their c crystallographic axes highly aligned normal to eggshell surface (a very sharp gaussian angular distribution, σ=0.14, was obtained by using the Rietveld method to model the preferred orientation function in the X-ray powder diffraction pattern). Elemental analysis revealed more Mg 2+ in the crystal layer than in cone layer of the eggshell. A high nitrogen content in the organic membrane is associated to a proteinaceous phase. The cone and palisade layers are composed of needle-shaped calcite crystals, which are more crystallized than in the crystal layer and in average with their c crystallographic axes oriented in all directions except for the one perpendicular to the eggshell surface. Due to the complex structure and the amorphous/crystal phase interactions, the heating at about 500 deg. C texturizes the crystals orienting them mainly along the c-axes normal to the inner eggshell surface

  19. Structural, spectroscopic and Thermal Studies of Potassium Di-hydrogen Citrate Crystal

    Directory of Open Access Journals (Sweden)

    N.D. Pandya

    2017-04-01

    Full Text Available Potassium dihydrogen citrate (KDC finds wide applications in food products. Pure potassium dihydrogen citrate crystal was grown by slow solvent evaporation technique at room temperature. Grown crystal exhibited needle like morphology. The powder XRD shows triclinic structure symmetry with lattice parameters a=11.820 Å, b=14.970 Å, c=9.442 Å with angles α = 91.60°, β = 93.35°, γ = 110°. The presence of various functional groups of grown crystal was confirmed by using FT-IR spectroscopy. The thermogram indicates the thermal stability of the sample up to 100oC and then decomposes slowly into oxide stage through two stages. The results are discussed here.

  20. Synthesis, thermal and nonlinear optical characterization of L-arginine semi-oxalate single crystals

    Science.gov (United States)

    Vasudevan, P.; Gokulraj, S.; Sankar, S.

    2012-06-01

    Optically good quality L-arginine semi-oxalate, an organic nonlinear optical crystal, has been synthesized from aqueous solution by slow evaporation method. Single crystal X-ray diffraction (XRD) analysis reveals that the synthesized L-arginine semi-oxalate crystal possesses triclinic structure with unit cell dimensions as a=5.05Å, b=9.73Å, c=13.12Å, α=111.030, β=92.790 and γ=91.910. The Fourier transform infra-red (FTIR) spectroscopy was analyzed and the presence of functional groups of L-arginine semi-oxalate was confirmed. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies show that the material is thermally stable up to 1460C and the melting point is 1500C. Kurtz and Perry powder technique confirms that the second harmonic generation (SHG) efficiency is 0.32 times that of standard organic materials urea and KDP.