High-temperature structural phase transitions of GexS1-x alloys studied by raman spectroscopy

Kotsalas, IP; Raptis, C

dc.contributor.author	Kotsalas, IP	en
dc.contributor.author	Raptis, C	en
dc.date.accessioned	2014-03-01T01:16:37Z
dc.date.available	2014-03-01T01:16:37Z
dc.date.issued	2001	en
dc.identifier.issn	0163-1829	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14122
dc.subject	High Temperature	en
dc.subject	Raman Spectroscopy	en
dc.subject	Structural Phase Transition	en
dc.subject.classification	Physics, Condensed Matter	en
dc.subject.other	alloy	en
dc.subject.other	germanium	en
dc.subject.other	sulfur	en
dc.subject.other	article	en
dc.subject.other	chemical structure	en
dc.subject.other	cooling	en
dc.subject.other	crystallization	en
dc.subject.other	high temperature procedures	en
dc.subject.other	melting point	en
dc.subject.other	phase transition	en
dc.subject.other	Raman spectrometry	en
dc.subject.other	stoichiometry	en
dc.title	High-temperature structural phase transitions of GexS1-x alloys studied by raman spectroscopy	en
heal.type	journalArticle	en
heal.identifier.primary	10.1103/PhysRevB.64.125210	en
heal.identifier.secondary	http://dx.doi.org/10.1103/PhysRevB.64.125210	en
heal.identifier.secondary	125210	en
heal.language	English	en
heal.publicationDate	2001	en
heal.abstract	A high-temperature Raman study of GexS1-x alloys is reported up to a temperature close to the melting point, including both Ge-rich (x=0.35) and S-rich (x=0.20,0.30) glasses, as well as the compound glass (g-GeS; x=1/3). The variation in the Raman spectra indicates that above certain temperatures g-GeS2 gradually crystallizes, first to the three-dimensional (3D) phase and then to the layered two-dimensional (2D) phase, with the latter being maintained up to melting point and upon subsequent cooling to room temperature. There is evidence that the controversial Al companion band of g-GeS2 evolves to a counterpart band of the 2D crystalline phase, implying that this band is due to symmetric stretch vibrations of S atoms in bridges of edge-sharing Ge(S-1/2)(4) tetrahedra, in agreement with a previous prediction. Similar two step irreversible crystallization to the 3D and 2D phases of GeS2 have been observed above T-g for the moderately rich in Ge (x=0.35) or in S (x=0.30) GexS1-x glasses, but at lower thresholds of crystallization temperature. In the strongly enriched in S (x=0.20) glass, though, crystallization takes place only to the 3D phase of GeS2, a process which is reversible after cooling the alloy to room temperature, i.e., the material returns to its initial amorphous phase. This reversible crystallization is explained in terms of the three-dimensional network of S-rich GexS1-x glasses which evolves only to the respective 3D crystalline phase lattice at high temperatures. It is pointed out that all GexS1-x glasses studied undergo a first-step transition to the 3D crystalline phase, which shows that the network of these glasses is, by large, three dimensional.	en
heal.publisher	AMERICAN PHYSICAL SOC	en
heal.journalName	Physical Review B - Condensed Matter and Materials Physics	en
dc.identifier.doi	10.1103/PhysRevB.64.125210	en
dc.identifier.isi	ISI:000171244400059	en
dc.identifier.volume	64	en
dc.identifier.issue	12	en
dc.identifier.spage	1252101	en
dc.identifier.epage	1252108	en