Size Dependence of a First Order Solid-Solid Phase Transition: The Wurtzite to Rock Salt Transformation in CdSe Nanocrystals

• Published in: Science (American Association for the Advancement of Science) Vol. 265; no. 5170; pp. 373 - 376
• Main Authors: Tolbert, S. H., Alivisatos, A. P.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 15.07.1994; American Association for the Advancement of Science
• Subjects: CADMIUM COMPOUNDS; CADMIUM SELENIDES; CHALCOGENIDES; Condensed matter: structure, mechanical and thermal properties; CRYSTAL-PHASE TRANSFORMATIONS; Crystallography; Crystals; Electromagnetic absorption; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Halites; Hysteresis; KINETICS; MATERIALS SCIENCE; Nanocrystals; PHASE TRANSFORMATIONS; Phase transitions; Physics; SELENIDES; SELENIUM COMPOUNDS 360202 > Ceramics, Cermets, & Refractories > Structure & Phase Studies; Solid state chemistry; Solid-solid transitions; Specific phase transitions; Surface energy; THERMODYNAMICS; Wave diffraction; Wurtzite; Finite size effect; Semiconductor materials; Inorganic compounds; Phase transformations; Transition element compounds; Cadmium sulfides; XRD; Experimental study; Size effect; Wurtzite structure; Absorption spectra; Hysteresis; Nanocrystal
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.265.5170.373

Measurements of the size dependence of a solid-solid phase transition are presented. High-pressure x-ray diffraction and optical absorption are used to study the wurtzite to rock salt structural transformation in CdSe nanocrystals. These experiments show that both the thermodynamics and kinetics of this transformation are altered in finite size, as compared to bulk CdSe. An explanation of these results in the context of transformations in bulk systems is presented. Insight into the kinetics of transformations in both bulk and nanocrystal systems can be gained.