2018
DOI: 10.1039/c7dt03912c
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Proton and oxygen ion conductivity in the pyrochlore/fluorite family of Ln2−xCaxScMO7−δ (Ln = La, Sm, Ho, Yb; M = Nb, Ta; x = 0, 0.05, 0.1) niobates and tantalates

Abstract: The tolerance factor is a good criterion to understand the structural transitions in LnCaScMO (Ln = La, Sm, Ho, Yb; M = Nb, Ta; x = 0, 0.05, 0.1). Decreasing the Ln ionic radius in LnScNb(Ta)O leads to a morphotropic transition from a pyrochlore to a fluorite-like structure. Ca-doping leads to a pyrochlore-to-fluorite transition in LnCaScMO (Ln = La, Sm) and a fluorite-to-pyrochlore transition in HoCaScNbO. Proton contribution to the total conductivity was observed for LnCaScNb(Ta)O (Ln = La, Sm; x = 0, 0.05, … Show more

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Cited by 32 publications
(15 citation statements)
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“…Thermogravimetric analysis was performed by using the NETZSCH STA 449C system (Netzsch, Selb, Germany) (30–1000 °C, heating rate of 10 K/min, Al 2 O 3 plate) in air. A detailed description of the experiment can be found in Reference [32].…”
Section: Experimental Partmentioning
confidence: 99%
See 1 more Smart Citation
“…Thermogravimetric analysis was performed by using the NETZSCH STA 449C system (Netzsch, Selb, Germany) (30–1000 °C, heating rate of 10 K/min, Al 2 O 3 plate) in air. A detailed description of the experiment can be found in Reference [32].…”
Section: Experimental Partmentioning
confidence: 99%
“…Recently, a Ca-doped 3+/5+ pyrochlore series, which also has a pyrochlore–fluorite morphotropic phase boundary, was shown to have proton conductivity [32], which increases in going from La 2−x Ca x ScNbO 7−x/2 to Sm 2−x Ca x ScNbO 7−x/2 , i.e., with increasing disorder in the pyrochlore structure, and completely disappears in fluorite Ln 2−x Ca x ScNbO 7−x/2 (Ln = Ho, Yb).…”
Section: Introductionmentioning
confidence: 99%
“…Possibly carbon "burnout” from crystalline pyrochlore phase leads to CO 2 release between 600 and 800°C and the anomalous behavior of the permittivity of the rare‐earth titanates in this temperature range . It is known, for example, that the two‐step water removal from La 2 ScNbO 7 is accompanied by its anomalous dielectric permittivity behavior in the temperature range of 350‐600°C …”
Section: Discussionmentioning
confidence: 99%
“…These materials can be used not only for obtaining efficient TBC. Their ionic conductivity increases significantly when they are doped with heterovalent ions, as like as in R 2 3+ M 2 4+ O 7 pyrochlores (R = Ln, Y; M = Ti, Zr, Hf) …”
Section: Introductionmentioning
confidence: 99%
“…3) The pyrochlore-type compound is represented by the general formula A 2 B 2 O 6 O and it is considered as a superstructure of the fluorite-type structure which has the general formula AO 2 . A larger sized A cation occupied at 16d site is generally an alkali metal, an alkaline earth metal or a rare earth metal, 19), 20) a B cation occupy at 16c sites is a transition metal while O and OBoccupy at 48f and 8b sites respectively. 21), 22) The ordered pyrochlore structure can be transformed into the disordered fluorite structure by decreasing the A site cation size 23) which transforms to a face centered cubic system.…”
Section: Introductionmentioning
confidence: 99%