Crystal structure and proton conductivity of BaSn_0.6Sc_0.4O_3-δ: insights from neutron powder diffraction and solid-state NMR spectroscopy

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Kinyanjui, Francis G, Norberg, Stefan T, Knee, Christopher S, Ahmed, Istaq, Hull, Stephen, Buannic, Lucienne, Hung, Ivan, Gan, Zhehong, Blanc, Frederic ORCID: 0000-0001-9171-1454, Grey, Clare P et al (show 1 more authors) and Eriksson, Sten G (2016) Crystal structure and proton conductivity of BaSn_0.6Sc_0.4O_3-δ: insights from neutron powder diffraction and solid-state NMR spectroscopy JOURNAL OF MATERIALS CHEMISTRY A, 4 (14). pp. 5088-5101. ISSN 2050-7488, 2050-7496

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Abstract

The solid-state synthesis and structural characterisation of perovskite BaSn<inf>1-x</inf>Sc<inf>x</inf>O<inf>3-δ</inf> (x = 0.0, 0.1, 0.2, 0.3, 0.4) and its corresponding hydrated ceramics are reported. Powder and neutron X-ray diffractions reveal the presence of cubic perovskites (space group Pm3m) with an increasing cell parameter as a function of scandium concentration along with some indication of phase segregation. ¹¹⁹Sn and ⁴⁵Sc solid-state NMR spectroscopy data highlight the existence of oxygen vacancies in the dry materials, and their filling upon hydrothermal treatment with D<inf>2</inf>O. It also indicates that the Sn⁴⁺ and Sc³⁺ local distribution at the B-site of the perovskite is inhomogeneous and suggests that the oxygen vacancies are located in the scandium dopant coordination shell at low concentrations (x ≤ 0.2) and in the tin coordination shell at high concentrations (x ≥ 0.3). ¹⁷O NMR spectra on ¹⁷O enriched BaSn<inf>1-x</inf>Sc<inf>x</inf>O<inf>3-δ</inf> materials show the existence of Sn-O-Sn, Sn-O-Sc and Sc-O-Sc bridging oxygen environments. A further room temperature neutron powder diffraction study on deuterated BaSn<inf>0.6</inf>Sc<inf>0.4</inf>O<inf>3-δ</inf> refines the deuteron position at the 24k crystallographic site (x, y, 0) with x = 0.579(3) and y = 0.217(3) which leads to an O-D bond distance of 0.96(1) Å and suggests tilting of the proton towards the next nearest oxygen. Proton conduction was found to dominate in wet argon below 700 °C with total conductivity values in the range 1.8 × 10^-4 to 1.1 × 10^-3 S cm^-1 between 300 and 600 °C. Electron holes govern the conduction process in dry oxidizing conditions, whilst in wet oxygen they compete with protonic defects leading to a wide mixed conduction region in the 200 to 600 °C temperature region, and a suppression of the conductivity at higher temperature.

Item Type:	Article
Uncontrolled Keywords:	3402 Inorganic Chemistry, 34 Chemical Sciences, 3406 Physical Chemistry
Depositing User:	Symplectic Admin
Date Deposited:	20 Sep 2016 15:26
Last Modified:	22 May 2026 23:48
DOI:	10.1039/c5ta09744d
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3003396
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