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dc.contributor.authorRotaru, Andrei
dc.contributor.authorMorrison, Finlay D.
dc.identifier.citationRotaru , A & Morrison , F D 2015 , ' Vogel-Fulcher analysis of relaxor dielectrics with the tetragonal tungsten bronze structure : Ba 6 MNb 9 O 30 (M = Ga, Sc, In) ' , Journal of Thermal Analysis and Calorimetry , vol. 120 , no. 2 , pp. 1249-1259 .
dc.identifier.otherPURE: 161518868
dc.identifier.otherPURE UUID: 452e40e1-4bd6-46b1-b28e-47839d0643a1
dc.identifier.otherScopus: 84939946626
dc.identifier.otherORCID: /0000-0002-2813-3142/work/48131863
dc.identifier.otherWOS: 000352480800021
dc.description.abstractIn-depth analysis of the relaxor behaviour of Ba6MNb9O30 (M= Ga, Sc, In) tetragonal tungsten bronze (TTB) ceramics was carried out. Powder x-ray diffraction and scanning electron microscopy were performed in order to confirm the formation of desired phases and to determine the microstructure. Low-temperature dielectric spectroscopy was used in order to characterise the dielectric properties of these materials; the degree of relaxor behaviour were investigated in relation with the increase of ionic radius of the M-cation on the B-site of the TTB structure. The dynamics of dielectric relaxation of dipoles was studied by fitting the dielectric permittivity data to the Vogel-Fulcher (VF) model in order to monitor the reproducibility and validity of the physical results. Restrictions to the VF fit were attempted besides the regular “free-fit” by constraining some of the fundamental relaxation parameters to physically sensible values. We show that Vogel-Fulcher fits are very sensitive to the fitting range resulting in a large range of fundamental parameters for the dielectric relaxation processes, and that the restriction of the frequency domain due to experimental noise or to instrumentation limits has a dramatic influence on the values obtained.
dc.relation.ispartofJournal of Thermal Analysis and Calorimetryen
dc.rights© Akadémiai Kiadó, Budapest, Hungary 2015. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final publication is available at Springer via
dc.subjectCanonical relaxorsen
dc.subjectLow temperature dielectric spectroscopyen
dc.subjectDipolar relaxationen
dc.subjectTetragonal tungsten bronzesen
dc.subjectVogel-Fulcher modelen
dc.subjectQD Chemistryen
dc.titleVogel-Fulcher analysis of relaxor dielectrics with the tetragonal tungsten bronze structure : Ba6MNb9O30 (M = Ga, Sc, In)en
dc.typeJournal articleen
dc.contributor.sponsorThe Royal Societyen
dc.contributor.sponsorThe Royal Societyen
dc.contributor.institutionUniversity of St Andrews. School of Chemistryen
dc.contributor.institutionUniversity of St Andrews. EaSTCHEMen
dc.description.statusPeer revieweden

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