9/6/2023 0 Comments Enthalpy vs entropy![]() The synthesized power showed well-defined XRD patterns corresponding to a pure rocksalt structure. Poudeu later verified the theory predictions by synthesizing the equimolar composition (Ge1/3Sn1/3Pb1/3S1/3Se1/3Te1/3) by a two-step solid-state reaction followed by fast quenching in liquid nitrogen. Despite being metastable at room temperature, these solid solutions can be preserved by fast cooling under ambient conditions. He found that the large configurational entropy from both anion and cation sublattices stabilizes the alloys into single-phase rocksalt solid solutions at the growth temperature. Using high throughput first-principles calculations, Kioupakis uncovered the complex interplay between the enthalpy and entropy in GeSnPbSSeTe high-entropy chalcogenide alloys. They tested their hypothesis on a 6-component II-VI chalcogenide alloy derived from the PbTe structure by mixing Ge, Sn, and Pb on the cation site, and S, Se, and Te on the anion site. ![]() Kioupakis and Poudeu hypothesized that this principle of entropy stabilization can be applied to overcome the synthesis challenges of semiconducting alloys that prefer to segregation into thermodynamically more stable compounds. ![]() Despite having a large enthalpy of mixing, these materials can surprisingly crystalize in a single crystal structure, enabled by the large configurational entropy in the lattice. Entropy, a thermodynamic quantity that quantifies the degree of disorder in a material, has been exploited to synthesize a vast array of novel materials by mixing eachcomponent in an equimolar fashion, from high-entropy metallic alloys to entropy-stabilized ceramics. ![]()
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