Filamentary crystal growth associated with impact craters from hypervelocity microparticles
Filamentary crystal growth associated with hypervelocity microparticles impact upon Cu foil
Berg, O. E.↗
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Skylab experiment performance evaluation manual. Appendix J: Experiment M555 gallium arsenide single crystal growth (MSFC)
Analyses for Experiment M555, Gallium Arsenide Single Crystal Growth (MSFC), to be used for evaluating the performance of the Skylab corollary experiments under preflight, inflight, and post-flight conditions are presented. Experiment contingency plan workaround procedure and malfunction analyses are presented in order to assist in making the experiment operationally successful.
Byers, M. S.↗
Morphological stability and fluid dynamics of vapor crystal growth
Research on morphological stability and fluid dynamics of crystal growth is discussed. Interfacial heat and mass transfer research is discussed. The finding of surface roughening is a precursor to a solid-solid phase transition was further quantified. Progress was obtained with the mass spectroscopic characterization of GeSe-Ge I sub 4.
Rosenberger, F. E.↗
Liquid drop stability for protein crystal growth in microgravity
It is possible to grow protein crystals for biomedical research in microgravity by deploying a protein-rich solution from a syringe, forming a drop in which crystallization can occur with the proper degree of supersaturation. Drop stability is critical to the success of this research, due to the large drop sizes which can be achieved in space. In order to determine the type of syringe tips most suitable to support these large drops, tests were performed during brief periods of weightlessness onboard the NASA KC-135 low-gravity simulation aircraft. The drops were analyzed using three simple models in which the samples were approximated by modified pendulum and spring systems. It was concluded that the higher frequency systems were the most stable, indicating that of the syringes utilized, a disk-shaped configuration provided the most stable environment of low-gravity protein crystal growth.
Owen, Robert B.↗
Opportunity for academic research in a low-gravity environment - Crystal growth
The history of basic and applied research on crystal growth (CG), especially of semiconductor materials, is reviewed, stressing the dominance (at least in the U.S.) of industrial R&D projects over academic programs and the need for more extensive fundamental investigations. The NASA microgravity research program and the recommendations of the University Space Research Association are examined as they affect the availability of space facilities for academic CG research. Also included is a report on ground experiments on the effectiveness of magnetic fields in controlling vertical Bridgman CG and melt stability, using the apparatus employed in the Apollo-Soyuz experiments (Witt et al., 1978); the results are presented in graphs and briefly characterized. The role of NASA's microgravity CG program in stimulating academic work on CG, the importance of convection effects, CG work on materials other than semiconductors, and NSF support of CG research are discussed in a comment by R. F. Sekerka.
Matthiesen, D. H.↗
Device and method for screening crystallization conditions in solution crystal growth
A device and method for detecting optimum protein crystallization conditions and for growing protein crystals in either 1g or microgravity environments comprising a housing, defining at least one pair of chambers for containing crystallization solutions is presented. The housing further defines an orifice therein for providing fluid communication between the chambers. The orifice is adapted to receive a tube which contains a gelling substance for limiting the rate of diffusive mixing of the crystallization solutions. The solutions are diffusively mixed over a period of time defined by the quantity of gelling substance sufficient to achieve equilibration and to substantially reduce density driven convection disturbances therein. The device further includes endcaps to seal the first and second chambers. One of the endcaps includes a dialysis chamber which contains protein solution in which protein crystals are grown. Once the endcaps are in place, the protein solution is exposed to the crystallization solutions wherein the solubility of the protein solution is reduced at a rate responsive to the rate of diffusive mixing of the crystallization solutions. This allows for a controlled approach to supersaturation and allows for screening of crystal growth conditions at preselected intervals.
Carter, Daniel C.↗
The Influence of Reduced Gravity on the Crystal Growth of Electronic Materials
The imperfections in the grown crystals of electronic materials, such as compositional nonuniformity, dopant segregation and crystalline structural defects, are detrimental to the performance of the opto-electronic devices. Some of these imperfections can be attributed to effects caused by Earth gravity during crystal growth process and four areas have been identified as the uniqueness of material processing in reduced gravity environment. The significant results of early flight experiments, i.e. prior to space shuttle era, are briefly reviewed followed by an elaborated review on the recent flight experiments conducted on shuttle missions. The results are presented for two major growth methods of electronic materials: melt and vapor growth. The use of an applied magnetic field in the melt growth of electrically conductive melts on Earth to simulate the conditions of reduced gravity has been investigated and it is believed that the superimposed effect of moderate magnetic fields and the reduced gravity environment of space can result in reduction of convective intensities to the extent unreachable by the exclusive use of magnet on Earth or space processing. In the Discussions section each of the significant results of the flight experiments is attributed to one of the four effects of reduced gravity and the unresolved problems on the measured mass fluxes in some of the vapor transport flight experiments are discussed.
Su, Ching-Hua↗
Device and Method for Screening Crystallization Conditions in Solution Crystal Growth
A device and method for detecting optimum protein crystallization conditions and for growing protein crystals in either 1 g or microgravity environments comprising a housing defining at least one pair of chambers for containing crystallization solutions. The housing further defines an orifice therein for providing fluid communication between the chambers. The orifice is adapted to receive a tube which contains a gelling substance for limiting the rate of diffusive mixing of the crystallization solutions. The solutions are diffusively mixed over a period of time defined by the quantity of gelling substance sufficient to achieve equilibration and to substantially reduce density driven convection disturbances therein. The device further includes endcaps to seal the first and second chambers. One of the endcaps includes a dialysis chamber which contains protein solution in which protein crystals are grown. Once the endcaps are in place. the protein solution is exposed to the crystallization solutions wherein the solubility of the protein solution is reduced at a rate responsive to the rate of diffusive mixing of the crystallization solutions. This allows for a controlled approach to supersaturation and allows for screening of crystal growth conditions at preselected intervals.
Carter, Daniel C.↗
New Directions in NASA's Biological Crystal Growth Program on the International Space Station
NASA's Biological Crystal Growth Program (BCG) on the International Space Station (ISS) is changing direction from the study of crystallization to an emphasis on producing crystals for structure determination in leading problems in structural biology. The program will consist of two phases. The first phase is during assembly of the ISS and will primarily utilize payloads that currently fly in the orbiter middeck but can be adapted for ISS. The second phase begins after assembly of the ISS is complete and BCG payloads will occupy part of the Biotechnology Facility aboard the ISS. Two types of BCG payloads will be flown. One will emphasize the production of crystals for structure determination back on Earth. These types of payloads will allow hundreds of crystallization conditions to be tested. The second type of payload will be designed to study the crystallization process with the primary aim of assisting the structural biology efforts. Access to these facilities will be through the NASA BCG Guest Investigators program, the NASA Research Announcement, and other opportunities currently being formulated. Details of the crystallization hardware, the application procedures, and the operational aspects of the program will be described.
Kundrot, Craig E.↗
New Directions in NASA's Biological Crystal Growth Program on the International Space Station
NASA's Biological Crystal Growth Program (BCG) on the International Space Station (ISS) is changing direction from the study of crystallization to an emphasis on producing crystals for structure determination in leading problems in structural biology. The program will consist of two phases. The first phase is during assembly of the ISS and will primarily utilize payloads that currently fly in the orbiter middeck but can be adapted for ISS. The second phase begins after assembly of the ISS is complete and BCG payloads will occupy part of the Biotechnology Facility aboard the ISS. Two types of BCG payloads will be flown. One will emphasize the production of crystals for structure determination back on Earth. These types of payloads will allow hundreds of crystallization conditions to be tested. The second type of payload will be designed to study the crystallization process with the primary aim of assisting the structural biology efforts. Access to these facilities will be through the NASA BCG Guest Investigators program, the NASA Research Announcement, and other opportunities currently being formulated. Details of the crystallization hardware, the application procedures, and the operational aspects of the program will be described.
Kundrot, Craig E.↗
Nucleation and Convection Effects in Protein Crystal Growth
Our work under this grant has significantly contributed to the goals of the NASA supported protein crystallization program. We have achieved the main objectives of the proposed work, as outlined in the original proposal: (1) We have provided important insight into protein nucleation and crystal growth mechanisms to facilitate a rational approach to protein crystallization; (2) We have delineated the factors that currently limit the x-ray diffraction resolution of protein crystals, and their correlation to crystallization conditions; (3) We have developed novel technologies to study and monitor protein crystal nucleation and growth processes, in order to increase the reproducibility and yield of protein crystallization. We have published 17 papers in peer-reviewed scientific journals and books and made more than 15 invited and 9 contributed presentations of our results at international and national scientific meetings.
Vekilow, Peter G.↗
Protein crystal growth in low gravity
The solubility and growth mechanism of canavalin were studied, and the applicability of the Schlieren technique to protein crystal growth was investigated. Canavalin which may be crystallized from a basic solution by the addition of hydrogen (H+) ions was shown to have normal solubility characteristics over the range of temperatures (5 to 25 C) and pH (5 to 7.5) studied. The solubility data combined with growth rate data gathered from the seeded growth of canavalin crystals indicated that the growth mechanism at high supersaturation ratios (>1.28) is screw dislocation like. A Schlieren apparatus was constructed and flow patterns were observed in Rochelle salt (sodium potassium tartrate), lysozyme, and canavalin. The critical parameters were identified as the change in density with concentration (dp/dc) and the change in index of refraction with concentration (dn/dc). Some of these values were measured for the materials listed.
Feigelson, Robert S.↗
Thermocapillary convection in microgravity crystal growth melts of indium-antimonide
Results of two recent crystal growth experiments conducted aboard Skylab are analyzed for thermoconvective aspects. Theoretical temperature and velocity profiles in the crystal melts are predicted via computer modeling. These results are compared with experimental data obtained from Skylab investigators. From theoretical considerations, both indium-antimonide experiments should have exhibited substantial thermocapillary convection, but did not due to probable oxide film interference and/or opposing solutal effects.
Bourgeois, S. V., Jr.↗
A numerical study of transient heat and mass transfer in crystal growth
A numerical analysis of transient heat and solute transport across a rectangular cavity is performed. Five nonlinear partial differential equations which govern the conservation of mass, momentum, energy and solute concentration related to crystal growth in solution, are simultaneously integrated by a numerical method based on the SIMPLE algorithm. Numerical results showed that the flow, temperature and solute fields are dependent on thermal and solutal Grashoff number, Prandtl number, Schmidt number and aspect ratio. The average Nusselt and Sherwood numbers evaluated at the center of the cavity decrease markedly when the solutal buoyancy force acts in the opposite direction to the thermal buoyancy force. When the solutal and thermal buoyancy forces act in the same direction, however, Sherwood number increases significantly and yet Nusselt number decreases. Overall effects of convection on the crystal growth are seen to be an enhancement of growth rate as expected but with highly nonuniform spatial growth variations.
Han, Samuel Bang-Moo↗
Microgravity polymer and crystal growth at the Advanced Materials Center for the Commercial Development of Space
The microgravity research programs currently conducted by the Advanced Materials Center for the Commercial Development of Space (CCDS) are briefly reviewed. Polymer processing in space, which constitutes the most active microgravity program at the Advanced Materials CCDS, is conducted in three areas: membrane processing, multiphase composite behavior, and plasma polymerization. Current work in microgravity crystal growth is discussed with particular reference to the development of the Zeolite Crystal Growth facility.
Mccauley, Lisa A.↗
Crystal growth in fused solvent systems
Research is reported on the growth of electronic ceramic single crystals from solution for the future growth of crystals in a microgravity environment. Work included growth from fused or glass solvents and aqueous solutions. Topics discussed include: crystal identification and selection; aqueous solution growth of triglycine sulphate (TGS); and characterization of TGS.
Ulrich, D. R.↗
Defects in silicon effect on device performance and relationship to crystal growth conditions
A relationship between material defects in silicon and the performance of electronic devices will be described. A role which oxygen and carbon in silicon play during the defects generation process will be discussed. The electronic properties of silicon are a strong function of the oxygen state in the silicon. This state controls mechanical properties of silicon efficiency for internal gettering and formation of defects in the device's active area. In addition, to temperature, time, ambience, and the cooling/heating rates of high temperature treatments, the oxygen state is a function of the crystal growth process. The incorporation of carbon and oxygen into silicon crystal is controlled by geometry and rotation rates applied to crystal and crucible during crystal growths. Also, formation of nucleation centers for oxygen precipitation is influenced by the growth process, although there is still a controversy which parameters play a major role. All these factors will be reviewed with special emphasis on areas which are still ambiguous and controversial.
Jastrzebski, L.↗
ISS-Crystal Growth of Photorefractive Materials (BSO): Critical Design Issues for Optimized Data Extraction from Space Experiments
Realization of the full potential of photorefractive materials in device technology is seriously impeded by our inability to achieve controlled formation of critical defects during single crystal growth and by difficulties in meeting the required degree of compositional uniformity on a micro-scale over macroscopic dimensions. The exact nature and origin of the critical defects which control photorefractivity could not as yet be identified because of gravitational interference. There exists, however, strong evidence that the density of defect formation and their spatial distribution are adversely affected by gravitational interference which precludes the establishment of quantifiable and controllable heat and mass transfer conditions during crystal growth. The current, NASA sponsored research at MIT is directed at establishing a basis for the development of a comprehensive approach to the optimization of property control during melt growth of photorefractive materials, making use of the m-g environment, provided in the International Space Station. The objectives to be pursued in m-g research on photorefractive BSO (Bi12SiO20) are: (a) identification of the x-level(s) responsible for photorefractivity in undoped BSO; (b) development of approaches leading to the control of x-level formation at uniform spatial distribution; (c) development of doping and processing procedures for optimization of the critical, application specific parameters, spectral response, sensitivity, response time and matrix stability. The presentation will focus on: the rationale for the justification of the space experiment, ground-based development efforts, design considerations for the space experiments, strategic plan of the space experiments, and approaches to the quantitative analysis of the space experiments.
Hyers, Robert W.↗