Materials Research Lecture

Modern advances in experimental and computational capabilities make realistic to develop new materials from design to discovery and development. The application of thermo-mechanical energy (by high pressures and temperatures) comparable to chemical bond energies in solids can contribute to this concept in unique ways, as it often converts simple molecular solids into novel three-dimensional network structures in high energy density states. Nitrogen is one of few systems unambiguously demonstrated the materials design to discovery, via the theoretical prediction¹ and subsequent discovery of cg-N above 110 GPa and 2000 K.^2,3 Since then, numerous forms of extended phases have been predicted in nitrogen and other molecular systems at various pressures, which have yet been discovered and thereby stimulated the present study. In this lecture, I will present our recent discoveries of novel extended phases in two isoelectronic molecular systems of nitrogen and carbon monoxide and discuss about a few thermodynamic and kinetic principles governing thermo-mechanically driven transformations in dense solids and solid mixtures.

References: ¹Mailhiot et al., Phys. Rev. B 46, 14419 (1992); ²Eremets et al., Nature Mat. 3, 558 (2004); ³Lipp, et al., Phys. Rev. B 76, 14113 (2007).