Complex Chalcogenide Structures

Abstract

Traditionally, the use of high temperatures to directly combine elements or simpler compounds into more complex ones has been quite successful in providing new materials. However, this approach does give rise to important synthetic limitations. For example, the reactions almost always proceed to the most thermodynamically stable products; the high energies involved often leave little room for kinetic control. These thermodynamically stable products are typically the simplest binary or ternary compounds, and because of their high lattice stability, they become synthetic obstacles. Second, the high reaction temperatures also dictate that only the simplest chemical building blocks can be used, that is, elements on the atomic level. Synthetic attempts using molecules of known structure are doomed because the high temperatures reduce the system to a thermodynamic minimum, thereby not alloying for the desired bond formation. Hence, multinary compounds can be more difficult to form, and the preference lies with more stable binary and ternary compounds. Being almost totally at the mercy of thermodynamics, the solid state chemist has traditionally relied on experience and intuition, rather than a set of predictable rules.