Homogeneity range, oxygen nonstoichiometry, thermal expansion and transport properties of La2-xSrxNi1-yFeyO4+delta / Gilev A. R.,Kiselev E. A.,Cherepanov V. A. // RSC ADVANCES. - 2016. - V. 6, l. 77. - P. 72905-72917.

ISSN/EISSN:

2046-2069 / нет данных

Type:

Article

Abstract:

A series of La2-xSrxNi1-yFeyO4+delta complex oxides adopting the K2NiF4-type structure (sp.gr. I4/mmm) was prepared via the decomposition of citrate-nitrate precursors, followed by multiple annealing treatments at 1100 degrees C in air. Strontium for lanthanum substitution in La2-xSrxNi1-yFeyO4+delta leads to a progressive increase of iron solubility (y) which reaches maximum values at x-1.0-1.2. The crystal structure of single-phase samples was refined by the Reitveld method. The unit cell volume increases with y and decreases with x in La2-xSrxNi1-yFeyO4+delta. The solid solutions of La2-xSrxNi1-yFeyO4+delta were shown by TGA to be over-stoichiometric (delta > 0) at x-0.5 and 0.6 and oxygen deficient (delta < 0) at x-0.8 within the temperature range of 25-1050 degrees C in air. The thermal expansion coefficient of La2-xSrxNi1-yFeyO4+delta increases with x and y, varying within the range of (12-16) x 10(-6) K-1 up to 700 degrees C in air. In the higher temperature range, the value of the TEC increases up to 20 x 10(-6) K-1 due to a chemical expansion contribution. The total conductivity and Seebeck coefficient were measured in air from RT to 1100 degrees C. The maximum conductivity value equal to 289 S cm(-1) was obtained for La2-xSrxNi1-yFeyO4+delta at 460 degrees C in air. The conduction is temperature activated for all samples within the composition range under study. The temperature dependencies of the Seebeck coefficient were explained in the approximation of the small-polaron hopping mechanism. The charge carriers were electron holes localized on nickel forming Ni3+ cations in low-and high-spin states.

Author keywords:

NEUTRON POWDER DIFFRACTION; ELECTRICAL-PROPERTIES; MIXED CONDUCTIVITY; PHASE-EQUILIBRIA; DEFECT STRUCTURE; LA2NIO4+DELTA; SR; STABILITY; SYSTEM; 0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1

DOI:

10.1039/c6ra13335e

Web of Science ID:

ISI:000381490100005

Соавторы в МНС:

Другие поля

Поле	Значение
Publisher	ROYAL SOC CHEMISTRY
Address	THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND
Language	English
Keywords-Plus	NEUTRON POWDER DIFFRACTION; ELECTRICAL-PROPERTIES; MIXED CONDUCTIVITY; PHASE-EQUILIBRIA; DEFECT STRUCTURE; LA2NIO4+DELTA; SR; STABILITY; SYSTEM; 0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1
Research-Areas	Chemistry
Web-of-Science-Categories	Chemistry, Multidisciplinary
Author-Email	Eugene.Kiselyov@urfu.ru
ResearcherID-Numbers	Cherepanov, Vladimir/E-6451-2014
ORCID-Numbers	Cherepanov, Vladimir/0000-0003-3653-6459
Funding-Acknowledgement	RFBR {[}16-33-00562]
Funding-Text	This work was financially supported by RFBR (project No 16-33-00562).
Number-of-Cited-References	42
Usage-Count-Last-180-days	2
Usage-Count-Since-2013	9
Journal-ISO	RSC Adv.
Doc-Delivery-Number	DT4ZK