Phase separation and internal strains in the mixed La0.5R0.5Ba2Cu3Oy compounds (R=rare-earth element)

Calamiotou, M; Gantis, A; Palles, D; Lampakis, D; Liarokapis, E; Koufoudakis, A

dc.contributor.author	Calamiotou, M	en
dc.contributor.author	Gantis, A	en
dc.contributor.author	Palles, D	en
dc.contributor.author	Lampakis, D	en
dc.contributor.author	Liarokapis, E	en
dc.contributor.author	Koufoudakis, A	en
dc.date.accessioned	2014-03-01T01:14:03Z
dc.date.available	2014-03-01T01:14:03Z
dc.date.issued	1998	en
dc.identifier.issn	0163-1829	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/12834
dc.subject	Phase Separation	en
dc.subject	Rare Earth Element	en
dc.subject.classification	Physics, Condensed Matter	en
dc.subject.other	SUPERCONDUCTORS	en
dc.subject.other	LANTHANIDES	en
dc.subject.other	ATMOSPHERE	en
dc.subject.other	YBA2CU3OX	en
dc.subject.other	R=Y	en
dc.title	Phase separation and internal strains in the mixed La0.5R0.5Ba2Cu3Oy compounds (R=rare-earth element)	en
heal.type	journalArticle	en
heal.identifier.primary	10.1103/PhysRevB.58.15238	en
heal.identifier.secondary	http://dx.doi.org/10.1103/PhysRevB.58.15238	en
heal.language	English	en
heal.publicationDate	1998	en
heal.abstract	The mixed phase La0.5R0.5Ba2Cu3Oy (where R is yttrium or another rare earth) has been prepared using a variation of the solid-state reaction technique. X-ray diffraction and Raman measurements have been carried out to study the effect of the mixed rare-earth substitution at the site of the Y atom. The x-ray-diffraction measurements show characteristic changes in the interatomic distances, which are indicative of strains in the unit cell. A strain-relaxation mechanism is proposed, attributed to the separation of phases. In the micro-Raman spectra, an increase of the A(g) mode frequency of the apex oxygen with increasing average La-R ionic radius is observed, the mode frequencies corresponding to the Ba and the Cu(2) atoms remain practically unaffected, while in some compounds a new mode appears at similar to 126 cm(-1). The in-phase vibrations of the plane oxygen atoms show a shift to a lower frequency compared with the RBa2Cu3Oy samples, similar to the one observed in the overdoped YBa2Cu3Oy (y greater than or equal to 6.92) system. Besides, the width of this phonon is considerably larger than lin the YBa2Cu3Oy compounds, attributable to the existence of phases with underdoped, optimally doped, and overdoped oxygen concentration. As concerns the changes induced in the B-1g Raman active mode of the out-of-phase vibrations of the plane oxygen atoms, they are indicative of phases rich in either La, R, or an intermediate phase. Differences observed from the Pr1-xRxBa2Cu3Oy compounds prove that the phase formation mechanism is not a pure ion-size effect. [S0163-1829(98)03635-5].	en
heal.publisher	AMERICAN PHYSICAL SOC	en
heal.journalName	Physical Review B - Condensed Matter and Materials Physics	en
dc.identifier.doi	10.1103/PhysRevB.58.15238	en
dc.identifier.isi	ISI:000077460000085	en
dc.identifier.volume	58	en
dc.identifier.issue	22	en
dc.identifier.spage	15238	en
dc.identifier.epage	15246	en