Crystal growth experiments

Over the last few years, we have made a number of novel discoveries using reactive salt fluxes in the crystal growth experiment of mixed-metal oxides. The most important outcome that these salt-inclusion solids have demonstrated is the propensity for structure- directing effects of the employed salt. These hybrid solids have revealed fascinating solid-state structures ranging from nanoclusters to three-dimensional open frameworks of current interest. Solids featuring mag-... 

Protein Crystal Growth. By the mid-1990s, the protein crystal growth experiments produced the most spectacular results of all the space... 

For InN [2], due to kinetic and thermodynamical barriers crystal growth experiments resulted in very small crystallites (5 - 50 pm) grown by slow cooling of the system from the temperatures exceeding the stability limit for InN. 

An important feature of protein crystal growth experiments is the need to carry out crystallization trials with very small quantities of scarce and expensive materials. When experiments are carried out in such small volumes (typically, 5—100 ju.1), it becomes difficult to define and control solution properties. The situation becomes particularly complicated when vapor diffusion or other nonequilibrium approaches to crystal growth are used, as these produce different and changing conditions throughout the small volumes involved. 

Figure 13. Typical variations in calcium, pH, log Pcog, and calcite saturation (Cl) during crystal growth experiments of Reddy ( SO, 35) in dilute Na-HC03—CaCl2 solutions...

Calculation of the term aH /aH ( s) in several low PCO2 crystal growth experiments gives values near 0.93 initially and increasing to 0.97 at the termination of the growth experiments. Thus th form of equations 21 and 22 is similar because the term aH /alT (s) is nearly constant and near unity. 

These calculations neither prove nor disprove our mechanism model, since the implied PCO2 (and pH) differences are qualitatively consistent. That is, during the crystal growth experiments, CO2 produced by CaCOa precipitation increases in the bulk fluid and some is lost to the atmosphere. This net flux of CO2 is consistent with the calculated higher surface CO2 partial pressures. 

Figure 15. Comparison of calculated pH in equilibrium with calcite at the hulk fluid Pco2 during crystal growth experiments of Reddy (30, 35) with the surface pH implied by our rate model and the observed rate as a function of calcite saturation (q)...

We thank Dr. M.M. Reddy of the New York State Department of Health for providing details of crystal growth experiments. Constructive criticism of an earlier version of this paper was provided by M.M. Reddy, and our colleagues at the U.S. Geological Survey, E.T. Sundquist and D.C. Thorstenson. 

Three different Kl concentrations as listed above were used in the shuttle experiments. Similar control experiments were done on earth. Videotaping of the crystal growth procedure was done with a television camera and still shots were also taken at various stages throughout the crystal growth experiments In both the shuttle and the laboratory. 

CRYSTAL GROWTH EXPERIMENTS Growth from the Melt... 

Initial crystal growth experiments using the more common low temperature fluxes such as B203, KF and PbO were unsuccessful. Subsequent DTA measurements suggested that YBC decomposes peritectically at about 1020°C. To overcome this difficulty, we searched for a liquidus field for crystal growth below the decomposition temperature. We concentrated our efforts on the pseudoternary YBC-BaCu02-CuO system. 

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