Apparent giant dielectric constants, dielectric relaxation, and ac-conductivity of hexagonal perovskites La{sub 1.2}Sr{sub 2.7} BO{sub 7.33} (B=Ru, Ir)
- Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, D-86135 Augsburg (Germany)
- Solid State Chemistry, University of Augsburg, D-86135 Augsburg (Germany)
We present a thorough dielectric investigation of the hexagonal perovskites La{sub 1.2}Sr{sub 2.7}IrO{sub 7.33} and La{sub 1.2}Sr{sub 2.7}RuO{sub 7.33} in a broad frequency and temperature range, supplemented by additional infrared measurements. The occurrence of giant dielectric constants up to 10{sup 5} is revealed to be due to electrode polarization. Aside of dc and ac conductivity contributions, we detect two intrinsic relaxation processes that can be ascribed to ionic hopping between different off-center positions. In both materials we find evidence for charge transport via hopping of localized charge carriers. In the infrared region, three phonon bands are detected, followed by several electronic excitations. In addition, these materials provide further examples for the occurrence of a superlinear power law in the broadband ac conductivity, which recently was proposed to be a universal feature of all disordered matter. - Graphical abstract: Frequency-dependent dielectric constant and conductivity of La{sub 1.2}Sr{sub 2.7}RuO{sub 7.33} at various temperatures. A frequency range of more than 16 decades is covered, revealing giant values of the dielectric constant, hopping conduction, a superlinear power law of the conductivity, and phononic and electronic excitations in the infrared region.
- OSTI ID:
- 20902491
- Journal Information:
- Journal of Solid State Chemistry, Vol. 179, Issue 12; Other Information: DOI: 10.1016/j.jssc.2006.09.005; PII: S0022-4596(06)00513-5; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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