Enhancement of high dielectric constant in CaCu\(_3\)Ti\(_4\)O$_1$$_2\(/RuO\)_2$ composites in the vicinity of the percolation threshold

• Published in: arXiv.org
• Main Authors: Mukherjee, Rupam, Lawes, Gavin, Nadgorny, Boris
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 18.03.2014
• Subjects: Composite materials; Copper oxides; Embedded systems; Energy dispersive X ray spectroscopy; Grain boundaries; Nanoparticles; Percolation; Permittivity; Scanning electron microscopy; Sol-gel processes; Titanium
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1403.4507

We observe the large enhancement in the dielectric response near the percolation threshold in a composite nanoparticle system consisting of metallic RuO\(_2\) grains embedded into dielectric CaCu\(_3\)Ti\(_4\)O$_1$$_2\( (CCTO) matrix and annealed at 1100OC. To understand the nature of the dielectric response, we compare CCTO fabricated by two different techniques, solid state process (CCTO\)_S$$_S\() and sol-gel process (CCTO\)_S$$_G\() with the intrinsic dielectric constant in both cases found to be on the order of 10\)^3\(-10\)^4\( at 10 kHz. For RuO\)_2\(/CCTO\)_S$$_S\( and RuO\)_2\(/CCTO\)_S$$_G$ composites and composites, an increase of the dielectric constant by factors of 7 and 5 respectively is observed in the vicinity of the percolation threshold of about 0.1, with moderate losses at room temperature. Scanning electron microscopy and Energy Dispersive X-ray spectroscopy indicate that the difference in the size of the effect may arise from the microstructure of the copper oxide enriched grain boundaries in the host CCTO.