Temperature dependence of Raman scattering and anharmonicity study of MgF2

Perakis, A; Sarantopoulou, E; Raptis, YS; Raptis, C

dc.contributor.author	Perakis, A	en
dc.contributor.author	Sarantopoulou, E	en
dc.contributor.author	Raptis, YS	en
dc.contributor.author	Raptis, C	en
dc.date.accessioned	2014-03-01T01:15:17Z
dc.date.available	2014-03-01T01:15:17Z
dc.date.issued	1999	en
dc.identifier.issn	0163-1829	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/13410
dc.subject	Raman Scattering	en
dc.subject	Temperature Dependence	en
dc.subject.classification	Physics, Condensed Matter	en
dc.subject.other	PHASE-TRANSITION	en
dc.subject.other	HIGH-PRESSURES	en
dc.subject.other	SPECTROSCOPY	en
dc.subject.other	SPECTRUM	en
dc.subject.other	CONSTANTS	en
dc.subject.other	CRYSTAL	en
dc.subject.other	RUTILE	en
dc.title	Temperature dependence of Raman scattering and anharmonicity study of MgF2	en
heal.type	journalArticle	en
heal.identifier.primary	10.1103/PhysRevB.59.775	en
heal.identifier.secondary	http://dx.doi.org/10.1103/PhysRevB.59.775	en
heal.language	English	en
heal.publicationDate	1999	en
heal.abstract	The temperature dependence of Raman spectra of MgF2 has been studied in the range 12-1100 K. Detailed consideration of the B1g phonon indicates that the (characteristic for the rutile-type crystals) anomalous softening with decreasing temperature is not associated with an incipient structural phase transition but with lattice contraction which alters the force constants. Combining the temperature data of this work and uniaxial stress Raman data [Pascual et al., Phys. Rev. B 24, 2101 (1981)], an anharmonicity analysis has been carried out in which the contributions of the volume thermal expansion and the pure temperature effects to the total observed frequency shifts have been determined and compared. These contributions are of the same sign (negative) for the A1g and Eg phonons, but of opposite sign for the B1g phonon, with the volume effect being dominant in all cases in the range 200-1100 K, thus confirming the anticipated ionic character of the MgF2 bonds. An accurate expression valid for uniaxial tetragonal crystals was formulated and used for the calculation of the volume contribution and the results were compared to those obtained by the isotropic approximation. In the case of MgF2 for T>200 K, it was found that the two sets of data differ by only 5-15% (depending on the phonon). © 1999 The American Physical Society.	en
heal.publisher	AMERICAN PHYSICAL SOC	en
heal.journalName	Physical Review B - Condensed Matter and Materials Physics	en
dc.identifier.doi	10.1103/PhysRevB.59.775	en
dc.identifier.isi	ISI:000078111600018	en
dc.identifier.volume	59	en
dc.identifier.issue	2	en
dc.identifier.spage	775	en
dc.identifier.epage	782	en