Publication Date:
2016-07-16
Description:
Scandium trifluoride (ScF 3 ), adopting a cubic ReO 3 -type structure at ambient pressure, undergoes a pronounced negative thermal expansion (NTE) over a wide range of temperatures (10 K–1100 K). Here, we report the size effects on the NTE properties of ScF 3 . The magnitude of NTE is reduced with diminishing the crystal size. As revealed by the specific heat measurement, the low-energy phonon vibrations which account for the NTE behavior are stiffened as the crystal size decreases. With decreasing the crystal size, the peaks in high-energy X-ray pair distribution function (PDF) become broad, which cannot be illuminated by local symmetry breaking. Instead, the broadened PDF peaks are strongly indicative of enhanced atomic displacements which are suggested to be responsible for the stiffening of NTE-related lattice vibrations. The present study suggests that the NTE properties of ReO 3 -type and other open-framework materials can be effectively adjusted by controlling the crystal size.
Print ISSN:
0003-6951
Electronic ISSN:
1077-3118
Topics:
Physics
Permalink
