Micevych+Delicate+Crystal+Growth+in+Gels

Abstract: RESEARCH PROJECT (LAB 14) DELICATE CRYSTAL GROWTH IN GELS. John Micevych. The purpose of this research project was to discover the effects of certain conditions on the growth of delicate copper crystals in a sodium silicate gel. By altering the temperature, type of metal, and amount of surface area, data was collected that provided evidence towards the conditions that would create the most, largest, fastest growing, and most well-defined crystals. In order to optimize the oxidation-reduction reaction between the copper ions in the gel and the metals’ atoms, it was concluded that magnesium was the most reactive (best tendency to give away electrons), higher temperatures produced faster and more crystal growth, and solid pieces of the metals were better than granulated because they sustained growth much more effectively.

Key Words: crystal, crystal lattice, oxidation-reduction reaction, ions, atoms, surface area



Summary Graphic: Table 3: Magnesium Table 4: Tin Table 5: Zinc Scientific Journal Summary: Crystal structure prediction using ab initio evolutionary techniques:
 * Conditions || Room temp, solid piece (2 tubes were run at theses conditions) || 40 C, solid piece || 7 C, solid piece ||
 * Size of crystal || Fairly large || Very Large || Small ||
 * Definition of crystal || Well-defined || Well-defined || Somewhat defined ||
 * Speed of formation || Fast || Very Fast || Slow ||
 * Amount of crystals || Somewhat many || Many || Somewhat many ||
 * Conditions || Room temp, granulated || Room temp, solid piece || 7 C, solid piece || 40 C, granulated ||
 * Size of crystal || Small || Very large || Large || Small ||
 * Definition of crystal || Badly defined || Very well-defined || Fairly well-defined || Badly defined ||
 * Speed of formation || Fast || Fast || Slow || Very fast ||
 * Amount of crystals || Many || Some || Not many at all || Very many ||
 * Conditions || Room temp, granulated || Room temp, solid piece || 7 C, solid piece || 40 C, granulated ||
 * Size of crystal || Small || Medium -sized || Small || Small ||
 * Definition of crystal || Very badly defined || Not very defined || Badly defined || Very badly defined ||
 * Speed of formation || Somewhat quickly || Slow || Slow || Fast ||
 * Amount of crystals || Many || Not many || Not many at all || Somewhat many ||

Two researchers at the Laboratory of Crystallography of the Department of Materials in Zurich, Switzerland have developed an efficient and reliable technique for predicting crystal structure. By utilizing ab initio, or total energy, calculations and an innovative evolutionary algorithm, they have come up with a method for discovering the most stable crystal structure for compounds at any pressure or temperature setting. In order to locate the global minimum of the free energy surface, which would result in the most stable structure, the researchers decided to apply their technique not to the entire surface, but only to a small, promising area. From there, they can use a self-improving method that continually locates more stable structures. This is specifically groundbreaking because it requires no experimental data, unlike most of the other techniques being investigated in laboratories across the globe. The algorithm has worked on both ionic and covalent compounds of varying complexity. In addition, it provides an opportunity to test crystal structures at conditions so extreme that they cannot yet be replicated on Earth. In the tens of tests completed so far, the researchers report a success rate that is almost 100%, further validating their method.

Oganov A., Glass C. 2006. Crystal structure prediction using ab initio evolutionary techniques: principles and applications. The Journal of Chemical Physics. 124(1):1-15.