1. Incipient ferroelectric to a possible ferroelectric transition in Te4+ doped calcium copper titanate (CaCu3Ti4O12) ceramics at low temperature as evidenced by Raman and dielectric spectroscopy
- Author
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Chandrabhas Narayana, Kachnar Varma, Nabadyuti Barman, and Priyank Singh
- Subjects
Permittivity ,Materials science ,Ferroelectric ceramics ,Analytical chemistry ,General Physics and Astronomy ,Mineralogy ,Relative permittivity ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferroelectricity ,lcsh:QC1-999 ,Dielectric spectroscopy ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,0103 physical sciences ,Calcium copper titanate ,symbols ,010306 general physics ,0210 nano-technology ,Raman spectroscopy ,lcsh:Physics - Abstract
Partial replacement of Ti4+ by Te4+ ions in calcium copper titanate lattice improved its dielectric behaviour mostly due to cubic-to-tetragonal structural transformation and associated distortion in TiO6 octahedra. The relative permittivity values (23–30 x 103) of Te4+ doped ceramics is more than thrice that of un-doped ceramics (8 x 103) at 1 kHz. A decreasing trend in relative permittivity with increasing temperature (50–300 K) is observed for all the samples. Barrett’s formula, as a signature of incipient ferroelectricity, is invoked to rationalize the relative permittivity variation as a function of temperature. A systematic investigation supported by temperature dependent Raman studies reveal a possible ferroelectric transition in Te4+ doped ceramic samples below 120 K. The possible ferroelectric transition is attributed to the interactions between quasi-local vibrations associated with the micro-clusters comprising TiO6 and TeO6 structural units and indirect dipole-dipole interactions of off-center B–cations (Ti4+ and Te4+) in double perovskite lattice.
- Published
- 2017