Hydrogen in mixed-valence perovskites: new approach to the chemical control of physical properties of HTSC and manganites

Información del proyecto

Identificador del acuerdo de subvención: INTAS-2000-00728

Proyecto cerrado

Fecha de inicio 1 Julio 2001

Fecha de finalización 30 Junio 2004

Financiado con arreglo a

• International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Coste total

Sin datos

Aportación de la UE

€ 150 000,00

Coordinado por

University of Turku
Finland

Objetivo

The project "Chemistry of redox and hydrogen intercalation reactions in mixed-valence perovskites at moderate temperatures: applications and control of basic properties" has been formulated based on contributions of experts from five NIS research groups and three groups from INTAS countries. The scheduled time for the project is 36 months. Dr E. Lahderanta from Wihuri Physical Laboratory, University of Turku, Finland, will be the project coordinator.

Oxides with perovskite-like structure play a crucial role as theory-test materials in different fields of solid state physics and have an outstanding capacity for variety of applications. In a number of perovskites the mixed valence of the transition metal results in electric and magnetic properties connected to such unique phenomena as high-temperature superconductivity (HTSC) and colossal magnetoresisitance (CMR).

Both of these attracts now interest. The specific characteristics of the respective materials are often tuned and varied for both fundamental and application purposes. The variation of chemical composition is one of the most powerful means to achieve the desirable control of the target properties. The originality of the proposal is based on a wide, systematic usage of hydrogen as a specific agent for chemical control of physical properties of cuprates and magnates. Besides samples obtained by inductive melting will be studied allowing to obtain more reliable data on bulk properties.

The main objectives are:
i) to study thermodynamics and reaction kinetics of dihydrogen and water vapours with cuprates (specially YBaCuO- and Bi - families) and manganites (specially with CMR effect), and of the coupled oxygenation-deoxygenation reactions;
ii) to characterise composition, structural changes, thermal and chemical stability of the perovskites. To study their depending on cation composition, oxygen and hydrogen content, and means of hydrogen charging;
iii) to investigate magnetic and electronic properties of the cuprates and manganites modified by hydrogen. To estimate contributions from electrons, holes and ions in the total charge transfer process. To estimate the influence of hydrogen on magnetic phase diagram;
iv) to evaluate the hierarchy of the atomistic phenomena of electron conductivity when hydrogen is added in mixed valence perovskite-like oxides. To apply the new knowledge to properties tuning and new materials engineering.

These goals will be achieved by bringing together seven groups with complementary expertise in synthesis, structural and chemical characterisation, defect chemistry, studies of electric and magnetic properties, exploitation of Raman, infrared and Mossbauer spectroscopy and computer modelling of complex oxides. Scientific references of the teams document their position at the frontier in solid-state chemistry and physics. A number of highly specialised and unique installations are available in the participating teams. Therefore, sharing this equipment and expertise of the participants is expected to bring a synergistic effect and to provide sound scientific results.

The systems to be investigated include hydrogen/water treated perovskites and perovskite- related oxides such as Ln1-xAxMnO3, where Ln = La, Pr, Ce; A = Ca, Sr, Ba; x=0, 0.33 0.5; YBa2Cu3Oy; PrBa2Cu3Oy; and Bi2212. Comparative study of these compounds modified by hydrogen or water vapour gives enhanced understanding of the role played by the transition metal-oxygen building units. Also it gives information of electronic structure that determine corresponding physical properties. Special attention will be given to the inherently oxygen- deficient phases with the aim to identify oxides capable to intercalate large amount of hydrogen. Thus, tuning of properties in hydrogen-modified perovskites will be obtained, and/or new compounds will be derived from the perovskite-like cuprates and manganites.

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Programa(s)

• IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Tema(s)

• 3 - Chemistry
• OPEN - OPEN Call

Convocatoria de propuestas

Datos no disponibles

Régimen de financiación

Datos no disponibles

Coordinador

University of Turku

• Aportación de la UE: Sin datos
• Dirección: 20014 Turku ; Finlandia
• Coste total: Sin datos

Participantes (6)

Academy of Sciences of Moldova

Moldavia

• Aportación de la UE: Sin datos
• Dirección: Academiei Str.5 ; 2028 Kishinev
• Coste total: Sin datos

Russian Academy of Sciences

Rusia

• Aportación de la UE: Sin datos
• Dirección: Politekhnicheskaya 26 ; 194021 St. Petersburg
• Coste total: Sin datos

Siberian Branch of Russian Academy of Sciences

Rusia

• Aportación de la UE: Sin datos
• Dirección: Kutateladze 18 ; 630128 Novosibirsk
• Coste total: Sin datos

Siberian branch of Russian Academy of Sciences

Kazajistán

• Aportación de la UE: Sin datos
• Dirección: Ibragimov St., 1 ; 480082 Almaty
• Coste total: Sin datos

Université Pierre et Marie Curie

Francia

• Aportación de la UE: Sin datos
• Dirección: 2 Rue Henri-Dunant ; 94320 Thiais
• Coste total: Sin datos

Ural Branch of the Russian Academy of Sciences

Rusia

• Aportación de la UE: Sin datos
• Dirección: Pervomaiskaia 91 ; 620219 Ekaterinburg
• Coste total: Sin datos