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 | Sciact - CRIS-system of Boreskov Institute of Catalysis

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 Full article

Journal

Dalton Transactions
ISSN: 1477-9226 , E-ISSN: 1477-9234

Output data

Year: 2018, Volume: 47, Number: 7, Pages: 2376-2392 Pages count : 17 DOI: 10.1039/c7dt03912c

Tags

HIGH-TEMPERATURE; RARE-EARTH; ELECTRICAL-CONDUCTIVITY; ELECTRONIC CONDUCTIVITY; DIFFUSION-COEFFICIENTS; MAGNETIC-PROPERTIES; CRYSTAL-STRUCTURE; PHASE-TRANSITION; LN(3)NBO(7) LN; OXIDES

Authors

Shlyakhtina A. V. ¹ , Pigalskiy K. S. ¹ , Belov D. A. ^1,2 , Lyskov N. V. ³ , Kharitonova E. P. ² , Kolbanev I. V. ¹ , Borunova A. B. ¹ , Karyagina O. K. ⁴ , Sadovskaya E. M. ^5,6 , Sadykov V. A. ^5,6 , Eremeev N. F. ⁵

Affiliations

1	Semenov Institute of Chemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, 119991 Russia
2	M.V. Lomonosov Moscow State University, Leninskie gory 1, Moscow, 119991 Russia
3	Institute of Problems of Chemical Physics, Russian Academy of Sciences, Academician Semenov ave. 1, Chernogolovka 142432, Russia
4	Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, 119991 Russia
5	Boreskov Institute of Catalysis, Siberian Branch of Russian Academy of Sciences, pr. Akad. Lavrentieva 5, Novosibirsk 630090, Russia
6	Novosibirsk State University, Pirogova str. 2, Novosibirsk 630090, Russia

Funding (4)

1	Russian Science Foundation	16-13-00112
2	Президиум РАН	14П/2017
3	Президиум РАН	35П/2018
4	Lomonosov Moscow State University

The tolerance factor is a good criterion to understand the structural transitions in Ln2−xCaxScMO7−δ (Ln = La, Sm, Ho, Yb; M = Nb, Ta; x = 0, 0.05, 0.1). Decreasing the Ln ionic radius in Ln2ScNb(Ta)O7 leads to a morphotropic transition from a pyrochlore to a fluorite-like structure. Ca2+-doping leads to a pyrochlore-to-fluorite transition in Ln2−xCaxScMO7−δ (Ln = La, Sm) and a fluorite-to-pyrochlore transition in Ho2−xCaxScNbO7−δ. Proton contribution to the total conductivity was observed for Ln2−xCaxScNb(Ta)O7−δ (Ln = La, Sm; x = 0, 0.05, 0.1) 3+/5+ pyrochlores and the maximum proton contribution was shown by Sm1.9Ca0.1ScMO6.95 (M = Nb, Ta), which are located at the boundary between pyrochlores and fluorites (comparative study of electrical conduction and oxygen diffusion). Proton conduction of Sm1.9Ca0.1ScNbO6.95 and Sm1.9Ca0.1ScTaO6.95 pyrochlores persists up to 800 and 850 °C, respectively. The conductivity of fluorite-like Ho2−xCaxScNbO7−δ (x = 0, 0.05) and Yb2ScNbO7 is dominated by the oxygen ion transport, in accordance with their energy activation values 1.09–1.19 eV. The dielectric permittivity and TG studies were used for the investigation of oxygen vacancy dynamics and water incorporation into the Ln2−xCaxScNb(Ta)O7−δ (Ln = La, Sm, Ho, Yb; x = 0, 0.05, 0.1) lattice. It is shown that oxygen vacancy-related dielectric relaxation in the range of 550–650 °C (ambient air), typical of pyrochlores and fluorites with pure oxygen ion conductivity, decreases and disappears for proton-conducting oxides.

Shlyakhtina A.V. , Pigalskiy K.S. , Belov D.A. , Lyskov N.V. , Kharitonova E.P. , Kolbanev I.V. , Borunova A.B. , Karyagina O.K. , Sadovskaya E.M. , Sadykov V.A. , Eremeev N.F.
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
Dalton Transactions. 2018. V.47. N7. P.2376-2392. DOI: 10.1039/c7dt03912c WOS Scopus РИНЦ AN OpenAlex

Submitted:	Oct 17, 2017
Accepted:	Jan 12, 2018
Published online:	Jan 12, 2018
Published print:	Feb 21, 2018

Web of science:	WOS:000424911300030
Scopus:	2-s2.0-85042119162
Elibrary:	35515443
Chemical Abstracts:	2018:81142
OpenAlex:	W2782702033

DB	Citing
Web of science	27
Scopus	31
Elibrary	28
OpenAlex	30