Problems with the thermogravimetric determination of oxygen stoichiometries in pure and rare-earth substituted La2RuO5

Riegg, Stefan; Müller, Thomas; Ebbinghaus, Stefan G.

doi:10.1016/j.solidstatesciences.2013.03.018

Cited by 1 publication

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“…The combination of TG and XAS investigations provides important information on the mixed valence states of copper and ruthenium containing oxides. 42 It was found that in Ln y Cu 3 Ru x Ti 4−x O 12+δ (Ln = La, Pr, Nd) considerable amounts of excess oxygen up to δ ≈ 0.7 can be incorporated. This finding is in accordance with earlier reports on Cu 2+x Ta 4 O 12+δ .…”

Section: Discussionmentioning

confidence: 99%

Valence properties of Cu and Ru in titanium-substituted LnCu₃Ru₄O_12+δ (Ln = La, Pr, Nd) investigated by XANES and TGA

et al. 2015

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In the solid-solution series La(y)Cu(3)RuxTi(4-x)O(12+δ) (0 ≤x≤ 4) the Cu and Ru electronic states are highly correlated. With increasing Ru content x the system properties change from a paramagnetic insulator with colossal dielectric constant to a heavy-fermion metal. To further elucidate the occurring phase transitions, the valences of Cu and Ru have been investigated utilizing XANES measurements at the Cu-K and the Ru-K absorption edges. It was found that the Ru oxidation number is close to +4 in all samples, while the Cu valence linearly decreases from +2 for the titanate (x = 0) to +1.6 for the ruthenate (x = 4). Additional thermogravimetric measurements have been used to determine the oxygen content and rather high oxygen excesses up to δ≈ 0.7 (for x = 0.5) were obtained. The additional oxygen for x < 2 is required to compensate the constant Ru +4 valence. Our findings are in accordance with the reported phase transitions of the magnetic and transport properties. Both the valence shift and the shapes of the absorption edges suggest a change from localized to itinerant character of the Cu electronic states with increasing x, while the Ru electrons remain localized. Analogous results concerning the valences were found for the Pr(y)Cu(3)RuxTi(4-x)O(12+δ) and Nd(y)Cu(3)RuxTi(4-x)O(12+δ) solid-solution series.

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Section: Discussionmentioning

confidence: 99%

Valence properties of Cu and Ru in titanium-substituted LnCu₃Ru₄O_12+δ (Ln = La, Pr, Nd) investigated by XANES and TGA

et al. 2015

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show abstract

Problems with the thermogravimetric determination of oxygen stoichiometries in pure and rare-earth substituted La2RuO5

Cited by 1 publication

References 32 publications

Valence properties of Cu and Ru in titanium-substituted LnCu₃Ru₄O_12+δ (Ln = La, Pr, Nd) investigated by XANES and TGA

Valence properties of Cu and Ru in titanium-substituted LnCu₃Ru₄O_12+δ (Ln = La, Pr, Nd) investigated by XANES and TGA

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Problems with the thermogravimetric determination of oxygen stoichiometries in pure and rare-earth substituted La2RuO5

Cited by 1 publication

References 32 publications

Valence properties of Cu and Ru in titanium-substituted LnCu3Ru4O12+δ (Ln = La, Pr, Nd) investigated by XANES and TGA

Valence properties of Cu and Ru in titanium-substituted LnCu3Ru4O12+δ (Ln = La, Pr, Nd) investigated by XANES and TGA

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Valence properties of Cu and Ru in titanium-substituted LnCu₃Ru₄O_12+δ (Ln = La, Pr, Nd) investigated by XANES and TGA

Valence properties of Cu and Ru in titanium-substituted LnCu₃Ru₄O_12+δ (Ln = La, Pr, Nd) investigated by XANES and TGA