Detail publikace
Syntéza, struktura a kyslíková tepelně programovaná desorpční spektra perovskitů La1-xCaxAlyFe1-yO3-d
CIHLÁŘ, J. DEL FAVERO, D. CIHLÁŘ, J. BUCHAL, A. VAN HERLE, J.
Český název
Syntéza, struktura a kyslíková tepelně programovaná desorpční spektra perovskitů La1-xCaxAlyFe1-yO3-d
Anglický název
Synthesis, structure and oxygen thermally programmed desorption spectra of La1-xCaxAlyFe1-yO3-d perovskites
Typ
článek v časopise - ostatní, Jost
Jazyk
en
Originální abstrakt
Perovskites La1-xCaxAlyFe1-yO3-d (x, y = 0 to 1) were prepared by high-temperature solid-state synthesis based on mixtures of oxides produced by colloidal milling. The XRD analysis showed that perovskites La0.5Ca0.5AlyFe1-yO3-d with a high Fe content (1 – y = 0.8-1.0) were of orthorhombic structure, perovskites with a medium Fe content (1 – y = 0.8-0.5) were of rhombohedral structure, and perovskite with the lowest Fe content (1 – y = 0.2) were of cubic structure. Thermally programmed desorption (TPD) of oxygen revealed that chemical desorption of oxygen in the temperature range from 200 to 1000 degC had proceeded in the two desorption peaks. The low-temperature alfa-peak (in the 200-550 degC temperature range) was brought about by oxygen liberated from oxygen vacancies; the high-temperature beta-peak (in the 550-1000 degC temperature range) corresponded to the reduction of Fe4+ to Fe3+. The chemidesorption oxygen capacity increased with increasing Ca content and decreased with increasing Al content in the perovskites. The Al3+ ions restricted, probably for kinetic reasons, the reduction of Fe4+ and the high-temperature oxygen desorption associated with it.
Český abstrakt
Perovskity La1-xCaxAlyFe1-yO3-d (x, y = 0 to 1) byly připraveny vysokoteplotní syntézou v pevné fázi ze směsí oxidů připravených koloidním mletím. Rtg. analýza ukázala, že perovskity La0.5Ca0.5AlyFe1-yO3-d s vysokým obsahem Fe (1 – y = 0.8-1.0) měly orthorhombickou strukturu, perovskity se středním obsahem Fe (1 – y = 0.8-0.5) měly rhombohedrickou strukturu a perovskity s nejnižším obsahem Fe (1 – y = 0.2) měly kubickou strukturu. Tepelně programovaná desorpce (TPD) kyslíku ukázala, že chemická desorpce kyslíku probíhala v teplotním rozsahu od 200 do 1000 degC ve dvou desorpčních pících. Nízkoteplotní alfa-pík (v rozsahu teplot 200-550 degC ) byl způsoben kyslíkem uvolněným z kyslíkových vakancí; vysokoteplotní beta-pík (v teplotním rozsahu 550-1000 degC ) odpovídal redukci Fe4+ na Fe3+. Chemisorpční kyslíková kapacita se zvyšovala s rostoucím obsahem Ca a snižovala se s rostoucím obsahem Al v perovskitech. Al3+ ionty omezovaly, pravděpodobně z kinetických důvodů, redukci Fe4+ a s ní související vysokoteplotní kyslíkovou redukci.
Anglický abstrakt
Perovskites La1-xCaxAlyFe1-yO3-d (x, y = 0 to 1) were prepared by high-temperature solid-state synthesis based on mixtures of oxides produced by colloidal milling. The XRD analysis showed that perovskites La0.5Ca0.5AlyFe1-yO3-d with a high Fe content (1 – y = 0.8-1.0) were of orthorhombic structure, perovskites with a medium Fe content (1 – y = 0.8-0.5) were of rhombohedral structure, and perovskite with the lowest Fe content (1 – y = 0.2) were of cubic structure. Thermally programmed desorption (TPD) of oxygen revealed that chemical desorption of oxygen in the temperature range from 200 to 1000 degC had proceeded in the two desorption peaks. The low-temperature alfa-peak (in the 200-550 degC temperature range) was brought about by oxygen liberated from oxygen vacancies; the high-temperature beta-peak (in the 550-1000 degC temperature range) corresponded to the reduction of Fe4+ to Fe3+. The chemidesorption oxygen capacity increased with increasing Ca content and decreased with increasing Al content in the perovskites. The Al3+ ions restricted, probably for kinetic reasons, the reduction of Fe4+ and the high-temperature oxygen desorption associated with it.
Klíčová slova anglicky
Perovskites; membranes; X-ray methods; powders-solid state reaction; chemisorption
Rok RIV
2006
Vydáno
01.01.2006
Nakladatel
Elsevier Science
ISSN
0955-2219
Časopis
Journal of the European Ceramic Society
Ročník
26
Číslo
14
Strany od–do
2999–3004
Počet stran
6
BIBTEX
@article{BUT43557,
author="Jaroslav {Cihlář} and David {Del Favero} and Jaroslav {Cihlář} and Antonín {Buchal} and Jan {Van herle},
title="Synthesis, structure and oxygen thermally programmed desorption spectra of La1-xCaxAlyFe1-yO3-d perovskites",
journal="Journal of the European Ceramic Society",
year="2006",
volume="26",
number="14",
month="January",
pages="2999--3004",
publisher="Elsevier Science",
issn="0955-2219"
}