Ferroelectric and structural properties of the tungsten bronze system K2Ln3+Nb5O15, Ln = La to Lu
| Autor: | L. E. Cross, J.R. Oliver, Jeffrey G. Nelson, Ratnakar R. Neurgaonkar |
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| Rok vydání: | 1990 |
| Předmět: |
Phase transition
Materials science Mechanical Engineering Mineralogy chemistry.chemical_element Dielectric engineering.material Tungsten Condensed Matter Physics Ferroelectricity Pyroelectricity Crystallography Lattice constant chemistry Mechanics of Materials engineering General Materials Science Orthorhombic crystal system Bronze |
| Zdroj: | Materials Research Bulletin. 25:959-970 |
| ISSN: | 0025-5408 |
| Popis: | The K2Ln3+Nb5O15 system has been investigated for a range of rare-earth ions (La3+ to Ho3+, Y3+). The temperature-dependent dielectric properties indicate that all but the La3+-containing materials have a tungsten bronze orthorhombic structure. Two phase transitions occur above room temperature, one paraelectric:ferroelectric and the other ferroelectric:ferroelastic. These transitions shift toward higher temperatures as the size of the rare-earth ion decreases. The lattice constant determination for this system indicates that the larger ions (La3+ to Gd3+) predominantly prefer the 12-fold coordinated site, Tb3+ to Ho3+ are distributed over both the 12- and 9-fold coordinated sites, and the smaller rare-earths (Er3+ to Lu3+) do not yield the tungsten bronze phase. Because of their low dielectric constants, these bronzes appear to be promising for some optical and pyroelectric detector applications. |
| Databáze: | OpenAIRE |
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