Phase Equilibria in the La-Me-Co-O (Me=Ca, Sr, Ba) Systems / Cherepanov V. A.,Gavrilova L. Ya.,Barkhatova L. Yu.,Voronin V. I.,Trifonova M. V.,Bukhner O. A. // IONICS. - 1998. - V. 4, l. 3-4. - P. 309-315.

ISSN/EISSN:

0947-7047 / нет данных

Type:

Article

Abstract:

The phase equilibria of the La-Me-Co-O systems (Me = Ca, Sr and Ba) were studied in air at 1100 degrees C. Two types of solid solution of general composition La(1-x)Me(x)CoO(3-delta) and (La(1-y) Me(y))(2)CoO(4) were found to exist in the systems. The limiting composition of La(1-x)Me(x)CoO(3-delta) lies at x = 0.8 for Me = Sr, Ba and between 0.3-0.5 for Me = Ca. It is shown that the rhombohedral distortion of the perovskite type La(1-x)Me(x)CoO(3-y) decreases while x increases. La(1-x)Me(x)CoO(3-delta) (Me = Sr, Ba) shows an ideal cubic structure at x = 0.5. The stability range of (La(1-y)Me(y))(2)CoO(4) was found to be 0.25 <= y <= 0.35 for Me = Ca, 0.3 <= y <= 0.55 for Me = Sr and 0.3 <= y <= 0.375 for Me = Ba. All phases have tetragonal K(2)NiF(4)-type crystal structure. Based on the XRD and neutron diffraction patterns of quenched samples, the phase diagrams (Gibbs triangles) are constructed for all systems. The phase equilibrium at low oxygen pressure is shown for the example of the La-Sr-Co-O system. The decomposition mechanism of La(1-x)Sr(x)CoO(3-delta) at 1100 degrees C for the samples with 0.5 < x < 0.8 within the oxygen pressure range -0.678 > log(Po(2)) > -2.25 can be written as follows: La(1-x)Sr(x)CoO(3-delta') = m SrCoO(2.5) + q/2 O(2) where x' > x `'. The decomposition mechanism of Lal\_ xSrx CoO3\_\~{} for the samples with x < 0.5 within the oxygen pressure range -2.25 > log(Po(2)) > -3.55 changes and can be written as follows: La(1-x)Sr(x)CoO(3-delta') = r La(1-x')Sr(x')COO(3-delta `') + w (La(1-y')Sr(y'))(2)CoO(4) + v CoO + f/2 O(2). The results are shown in ``logPo(2)-composition{''} diagrams.

Author keywords:

нет данных

DOI:

10.1007/BF02375959

Web of Science ID:

ISI:000208027800019

Соавторы в МНС:

Другие поля

Поле	Значение
Month	MAY
Publisher	SPRINGER HEIDELBERG
Address	TIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANY
Language	English
Research-Areas	Chemistry; Electrochemistry; Physics
Web-of-Science-Categories	Chemistry, Physical; Electrochemistry; Physics, Condensed Matter
ResearcherID-Numbers	Cherepanov, Vladimir/E-6451-2014 Voronin, Vladimir/J-7733-2013
ORCID-Numbers	Cherepanov, Vladimir/0000-0003-3653-6459 Voronin, Vladimir/0000-0002-3901-9812
Number-of-Cited-References	18
Usage-Count-Since-2013	22
Journal-ISO	Ionics
Doc-Delivery-Number	V18TT