Crystal Growth Apparatus Research Articles

Experimental investigation of Marangoni convection and vibration-induced crystal motion during protein crystal growth

The occurrence of Marangoni convection during cytochrome c’ crystal growth and vibration-induced motion of lysozyme crystals were investigated using a High Density Protein Crystal Growth (HDPCG) apparatus. Particle image velocimetry was used to visualize fluid motion, but no particle motion was observed, which suggests that under the experimental conditions used, Marangoni convection is not a significant cause of fluid and crystal motion. When horizontal vibrations of controlled amplitude and frequency were applied to the HDPCG apparatus, lysozyme crystals located on the liquid-vapour interface of the HDPCG cell made significant movements up to 0.5mm in amplitude and velocities reaching 0.06mm/s. These results from the Marangoni convection and horizontal vibration experiments suggest that protein crystal movements observed in past space experiments were most likely caused by g-jitter on the spacecraft rather than Marangoni convection.

Thermodynamic analyses of gases formed during the EFG sapphire growth process

Shaped sapphire crystals obtained by the edge-defined film fed growth (EFG) method almost always contain a typical defect, the so-called “voids”, which affect the optical quality of the crystals. The origin of the trapped voids is not yet clarified. One of the hypotheses is concerned with gas formation in the crystal growth setup chamber. The goal of this paper is to study the species of the gases resulting from various chemical reactions between the different components of the crystal growth apparatus, such as the charge (Al 2O 3), the crucible and the shaper material (Mo or W) and the screens and other details made from graphite (C). In order to obtain the partial pressure of the gas species in the growth chamber the thermodynamic calculations were performed using the complex equilibrium code—Gemini2—that minimizes the free enthalpy formation. Carbon monoxide (CO) becomes the most important gas species when one of the growth setup components is made from graphite. The various gas species resulting from different reactions are trapped in the crystal during the growth process and affect the crystal quality. In order to eliminate the contamination of the crystals, this type of calculation should be profitable for a better choice of the crucible, shaper and other set-up detail material.

An Apparatus for Crystal Growth by the Hydrothermal Method under Rotating Heat Field Conditions

The design of a setup for crystal growth by the hydrothermal method under conditions of a rotating heat field is described. A temperature control system with a device for the dynamic switching-on of the heating elements of the growth furnace is described. The amplitude–frequency characteristics of the heat fields in the empty autoclave are presented.

Characterization of the protein crystal growth apparatus for microgravity aboard the space station

We have conducted experiments to determine the equilibration rates of some major precipitants used in protein crystallography aboard the International Space Station (ISS). The solutions were placed in the Protein Crystallization Apparatus for Microgravity (PCAM) which mimic Cryschem sitting drop trays. The trays were placed in cylinders. These cylinders were placed inside a Single locker Thermal Enclosure System (STES), and were activated for different durations during the flight. Bumpers pressed against elastomers seal drops in a deactivated state during pre-flight and prior to transfer to the ISS. Activation occurs while in flight on the ISS by releasing the bumpers allowing the drops to be exposed to the reservoir. PCAM was flown to the ISS on STS 100, Flight 6A, on April 19, 2001. Six series of equilibration experiments were tested for each precipitant with a small amount of Green Fluorescent Protein (GFP). Cylinder 10 was never activated, 7 was activated for 40 days, 8 was activated for 20 days, 9 was activated for 10 days, 11 was activated for 4 days and 12 was activated for 2 days. Upon the return to Earth by STS 104 on July 24,2001 the samples were transferred to Marshall Space Flight Center. The samples were then brought to the lab and the volumes of each sample were measured.

Intrinsic fluorescence as a potential rapid scoring tool for protein crystals

Genomics is on the verge of creating a large number of proteins for structure determination. Since X-ray crystallography is the main tool for determining protein structure, a corresponding large number of X-ray diffraction experiments will have to be performed. However, X-ray analysis is labor intensive so that the question of which protein crystal to choose for X-ray analysis from the vast pool of candidates becomes important from an economics standpoint. It is desirable to have a rapid and efficient method to score protein crystals regarding their likelihood for being of diffraction quality. We propose intrinsic protein fluorescence as a scoring tool and report preliminary data that demonstrate correlation between fluorescence spectra of single crystals and their internal order as determined by X-ray crystallography. Specifically, fine structure and maxima of fluorescence emission spectra of lysozyme, hyaluronate lyase, and germination protease crystals were found to correlate with resolution and mosaicity determined by X-ray analysis. If the correlation exhibited by these three proteins reflects a general relationship for the majority of protein crystals, a rapid fluorescence assay for scoring crystals can be developed and adapted for a variety of configurations of high throughput crystal growth apparatus.

00/00601 The characterisation of coals and their respective chars formed at 1300°C in a drop tube furnace

A novel crystal growth apparatus which separates the source and growth regions of a vapour transport system into separate vertical furnaces connected by a horizontal transport passage has been developed. The transport passage incorporates a flow restrictor which regulates the mass flow and decouples it from the source–sink temperature difference. Growth takes place on a seed crystal past which the growth envelope is dynamically pumped to ensure that the transport is diffusionless. This “multi-tube” arrangement offers several advantages over conventional linear vapour transport systems. In addition to control of the mass transport, source and growth regions are thermally decoupled and there is noninvasive optical access to both source and crystal growth regions and for in situ vapour pressure monitoring. In this paper, the results of in situ vapour pressure measurements made during the growth of a boule of cadmium telluride are presented and a flow model, which accounts for the significant molecular component of the transport, is developed and used to calculate the corresponding mass flows. This system offers the potential to give improved control of the nucleation and subsequent growth of large single crystals of high-vapour pressure opto-electronic materials such as the II–VI compounds.

An apparatus for crystal growth under heat field rotation conditions

An apparatus for crystal growth under heat field rotation conditions

A novel “multi-tube” vapour growth system and its application to the growth of bulk crystals of cadmium telluride

A novel crystal growth apparatus which separates the source and growth regions of a vapour transport system into separate vertical furnaces connected by a horizontal transport passage has been developed. The transport passage incorporates a flow restrictor which regulates the mass flow and decouples it from the source–sink temperature difference. Growth takes place on a seed crystal past which the growth envelope is dynamically pumped to ensure that the transport is diffusionless. This “multi-tube” arrangement offers several advantages over conventional linear vapour transport systems. In addition to control of the mass transport, source and growth regions are thermally decoupled and there is noninvasive optical access to both source and crystal growth regions and for in situ vapour pressure monitoring. In this paper, the results of in situ vapour pressure measurements made during the growth of a boule of cadmium telluride are presented and a flow model, which accounts for the significant molecular component of the transport, is developed and used to calculate the corresponding mass flows. This system offers the potential to give improved control of the nucleation and subsequent growth of large single crystals of high-vapour pressure opto-electronic materials such as the II–VI compounds.

The effects of microgravity on protein crystallization: evidence for concentration gradients around growing crystals

Atomic force microscopy (AFM) investigations have revealed that macromolecular crystals, during their growth, incorporate an extensive array of impurities. These vary from individual molecules to large particles, and microcrystals in the micron size range. AFM, along with X-ray topology, has further shown that the density of defects and faults in most macromolecular crystals is very high in comparison with conventional crystals. The high defect density is a consequence of the incorporation of impurities, misoriented nutrient molecules, and aggregates of molecules. High defect and impurity density, contributes to a deterioration of both the mechanical and the diffraction properties of crystals. In microgravity, access by impurities and aggregates to growing crystal surfaces is restricted due to altered fluid transport properties. We designed, and have now constructed an instrument, the observable protein crystal growth apparatus (OPCGA) that employs a fused optics, phase shift, Mach–Zehnder interferometer to analyze the fluid environment around growing crystals. Using this device, which will ultimately be employed on the international space station, we have, in thin cells on earth, succeeded in directly visualizing concentration gradients around growing protein crystals. This provides the first direct evidence that quasi-stable depletion zones formed around growing crystals in space may explain the improved quality of macromolecular crystals grown in microgravity. Further application of the interferometric technique will allow us to quantitatively describe the shapes, extent, and magnitudes of the concentration gradients and to evaluate their degree of stability.

An Apparatus for Epitaxial Growth of Crystals on Stretched Polymer Films under a Controlled Atmosphere

An Apparatus for Epitaxial Growth of Crystals on Stretched Polymer Films under a Controlled Atmosphere

An apparatus for growth of small crystals from solutions

An apparatus for growth of small crystals from solutions

Radiation heat transfer of a Czochralski crystal growth furnace with arbitrary specular and diffuse surfaces

A numerical method is presented for predicting radiation heat transfer from axisymmetric bodies consisting of numerous arbitrary ring elements. Each ring element has the combined characteristics of specular and diffuse surfaces. The accuracy of the method was verified using a simple configuration. Good agreement between the present numerical and analytical solutions was obtained, and the effect of specular reflectivity was investigated. As a numerical example, radiation heat transfer of the Czochralski crystal growth apparatus was presented. The effect of specular reflection on temperature distribution on the various surfaces was examined. The present radiation transfer method was combined with the finite element package ABAQUS for conduction analysis, and the effect of specular reflectivity on temperature distribution and surface heat flux was investigated.

Crystallization in a laboratory chamber furnace

An apparatus for crystal growth from the melt, based on Stober's method and realized in our laboratory, is described.

Control apparatus for single crystal growth in aqueous solution method

Abstract A new technique has been developed for controlling the crystal‐growth rate in the aqueous solution method. This technique provides a programmable preset of the temperature evolution of solution. Initially, the growth rate is kept slow to ensure good crystal quality. Gradually the rate is accelerated to increase the growth efficiency. A simple control mechanism is devised to achieve a very slow and pre‐determined cooling rate, which can be adapted to the temperature‐related characteristics of various solutions and thermistor sensor. Single crystal growth of KDP has been demonstrated. The result verifies our prediction that a linear growth rate of the crystal dimension with a good seed‐to‐grown crystal interface can be obtained programmatically.

Laser scattering in a hanging drop vapor diffusion apparatus for protein crystal growth in a microgravity environment

One type of hardware used to grow protein crystals in the microgravity environment aboard the US space shuttle is a hanging drop vapor diffusion apparatus (HDVDA). In order to optimize crystal growth conditions, dynamic control of the HVDA is desirable. A critical component in the dynamically controlled system is a detector for protein nucleation. We have constructed a laser scattering detector for the HDVDA capable of detecting the nucleation stage. The detector was successfully tested for several scatterers differing in size using dynamic light scattering techniques. In addition, the ability to detect protein nucleation using the HDVDA was demonstrated for lysozyme.

Crocodile: An automated apparatus for organic crystal growth from solution

CROCODILE ( CROissance de Cristaux Organiques par DIffusion Liquide dans l' Espace) is a space instrument dedicated to crystal growth from solution. The selected material N (4 nitrophenyl) (L) prolinol (NPP) is the result of studies on organic crystal in the frame of an extended program initiated by CNES for many years. The apparatus was flown aboard PHOTON, an automatic satellite, in April 1990, for a flight duration of more than 15 days. This paper describes the instrument design, with emphasis on specific and original technology well adapted to crystal growth from solution, and extendable to any space experiment on fluids. Preliminary details of the flight campaign will also be discussed.

Protein crystal growth of Ribonuclease A and Pancreatic Trypsin Inhibitor aboard the MASER 3 rocket

The growth of bovine Ribonuclease A (RNase A) and bovine Pancreatic Trypsin Inhibitor crystals has been studied simultaneously aboard MASER 3, a sounding rocket, and in a ground reference unit. For crystallization to take place within the 7 min and 15 s of microgravity during the flight, both macro- and macro-seed techniques of supersaturated protein solutions were employed. It was found that the convection-free environment of the MASER 3 protein crystal growth apparatus produced more and larger crystals than the ground reference unit. The RNase A crystals grown in microgravity diffracted X-rays to 1.06 Å resolution, approximately 0.2 Å higher resolution than previously observed in terrestrially grown RNase A crystals. The refined structure based on these data contains new features not seen in the lower resolution structures.

An apparatus for crystal growth in the undergraduate laboratory

A modification of Stober's apparatus is presented for growing crystals in a laboratory chamber furnace. In addition to simplicity, the proposed apparatus has the following advantages: (a) absence of mechanical shocks; (b) spontaneous change and self-adjusting to most convenient crystallisation rate of the substance; (c) possibility of growing crystals in vacuum or an inert atmosphere. A formula for the crystallisation rate has been derived and analysed.

A new apparatus for double-crucible LEC GaAs crystal growth

We have developed a new apparatus for double-crucible LEC crystal growth in combination with the use of an X-ray transmission imager during growth. We found that the temperature fluctuations drop to less than half of those for the conventional LEC technique and that the In concentration along the growth direction moved away from the normal freezing curve and approached the calculated curve for zone melting. This fact suggests that our apparatus has a potential for growing GaAs crystals with a homogeneous impurity distribution along growth direction.

Growth of organic crystals in a microgravity environment

The usefulness of a three-chambered diffusion apparatus for organic crystal growth in a microgravity environment has been demonstrated. Crystal growth of urea is discussed.