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Structural and dielectric studies of some niobate-titanate systems |
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| Authors: | A M Varaprasad A L Shashi Mohan D K Chakrabarty A B Biswas |
| Affiliation: | (1) Solid State Laboratory, Chemistry Department, Indian Institute of Technology, 400 076 Bombay, India;(2) Present address: Hindustan Lever Research Centre, 400 093 Bombay, India;(3) Present address: Grindwell-Norton Ltd., 560 049 Bangalore, India |
| Abstract: | Ferroelectric ceramics of the general formulax (Li1/2 La1/2 TiO3) (1−x) (LiNbO3) have been found to have tungsten bronze (TTB) and ilmenite type structure in the ranges 0·8≤x≤1·0 and 0≤x≤0·2 respectively. The system is biphasic in the other ranges. All single phase materials exhibit dielectric anomalies in the temperature range 300–600 K. The high dielectric constant of the TTB phase is explained as due to the existence of localised rotational excitons arising from a large number of defect structural units and their coupling with one of the low frequency lattice modes. Information about the lattice modes to which the rotational excitons are coupled has been obtained from Raman spectra. Deceased |
| Keywords: | Dielectrics ceramics phase transitions niobate-titanate systems |
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