Synthesis,structure and oxygen thermally programmed desorption spectra of La1?xCaxAlyFe1?yO3?δ perovskites |
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| Affiliation: | 1. Institute of Material Science and Engineering, Brno University of Technology, Technicka 2, 616 69 Brno, Czech Republic;2. Institute of Material Chemistry, Brno University of Technology, Purkynova 118, 612 00 Brno, Czech Republic;3. Laboratoire d’Energe’tique Industrielle, EPFL, CH-1015 Lausanne, Switzerland;1. College of Materials Science and Engineering, Fuzhou University, Fuzhou 350116, PR China;2. Quanzhou Arts and Crafts Vocational College, Quanzhou 362500, PR China;1. Instituto de Cerámica y Vidrio, CSIC, C/ Kelsen no. 5, 28049 Madrid, Spain;2. Department of Materials, Imperial College, Prince Consort Road, London SW7 2BP, UK;1. Department of Physics, University of Peshawar, Peshawar, KP, Pakistan;2. Department of Physics, Islamia College University, Peshawar, KP, Pakistan;3. Department of Physics, University of Science and Technology, Bannu, KP, Pakistan;4. Department of Physics and EHSRC, University of Ulsan, Ulsan 680-749, Republic of Korea;5. Department of Materials Science and Engineering, Institute of Space Technology, Islamabad, 44000, Pakistan;1. SPCTS, CNRS, ENSCI, Université de Limoges, CEC, 12 Rue Atlantis, 87068, Limoges, France;2. Air Liquide, Centre de Recherche Claude-Delorme, 1 Chemin de La Porte des Loges, B.P. 126 Les Loges-en-Josas, 78654, Jouy-en-Josas Cedex, France;3. ADEME, 20, Avenue Du Grésillé, BP 90406 49004, Angers Cedex 01, France |
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| Abstract: | Perovskites La1?xCaxAlyFe1?yO3?δ (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?δ 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 °C had proceeded in the two desorption peaks. The low-temperature α-peak (in the 200–550 °C temperature range) was brought about by oxygen liberated from oxygen vacancies; the high-temperature β-peak (in the 550–1000 °C 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. |
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