Structure and dielectric properties of Ln3NbO7 (Ln = Nd,Gd, Dy,Er, Yb and Y) |
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| Affiliation: | 1. Laboratório de Materiais Luminescentes Micro e Nanoestruturados – Mater Lumen, Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, CEP 14040-901 Ribeirão Preto, SP, Brazil;2. Instituto de Engenharia de Várzea Grande, Universidade Federal de Mato Grosso, Várzea Grande, Brazil;3. Chimie Paris Tech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris, 11 Rue Pierre et Marie Curie, 75005 Paris, France;4. Department of Power Engineering, Photonics and Lighting Technology, Faculty of Electrical Engineering, Bialystok University of Technology, Wiejska Street 45D, 15-351 Bialystok, Poland;5. Department of Silicate Chemistry and Macromolecular Compounds, Faculty of Materials Science and Ceramics, AGH University of Science and Technology, A. Mickiewicza Av. 30, 30-059 Krakow, Poland;1. G.G. Devyatykh Institute of Chemistry of High-Purity Substances RAS, Nizhny Novgorod, Russia;2. Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia;1. CNRS, ICMCB, UPR 9048, F-33600 Pessac, France;2. Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac, France;3. Bordeaux INP, ICMCB, UPR 9048, F-33600 Pessac, France |
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| Abstract: | The structure and dielectric properties of Ln3NbO7 (Ln = Nd, Gd, Dy, Er, Yb and Y) ceramics are investigated. With decreasing ionic radius of Ln3+, the stable crystal structure of the compounds shifts from orthorhombic weberite to defect fluorite. It is experimentally observed that, with the exception of Gd3NbO7, the room temperature real part of the relative permittivity of Ln3NbO7 ceramics decreases from approximately 40 to 30 (at 1 MHz) with increasing ionic radius of Ln3+. The observed imaginary part of the relative permittivity is in order of 10−2 to 10−1 (room temperature and 1 MHz) and it is relatively stable up to 80 °C, where it increases with a rise in temperature. Interesting exceptions of these trends are Nd3NbO7 that crystallizes with a weberite-type structure and shows large positive temperature variation of the dielectric properties, and Gd3NbO7 that crystallized in a weberite related structure and displays frequency and temperature dependent dielectric relaxation behavior. |
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