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Deficient or excessive CuO-TiO <sub/>2</sub> phase influence on dielectric properties of CaCu <sub/>3</sub> Ti <sub/>4</sub> O <sub/>12</sub> ceramics
摘要： The influence of the CuO–TiO2 phase (CT) on dielectric properties of the CCTO ceramic was investigated. CaCuXTiYO12 (CCXTYO) powders were prepared based on the coprecipitated method, where 2.70 ≤ x ≤ 3.30 and 3.25 ≤ y ≤ 4.75. XRD patterns confirmed the presence of CCTO and also the secondary phases as CuO, TiO2 and CaTiO3 for each sample and aided in its quantification. Scanning Electron Microscopy (SEM) shows secondary phases evolution in the grain boundaries, and its influence on size and morphology of the grains. Impedance spectroscopy measurements showed that the ceramics with lower amount of CuO and TiO2 phases (CT/deficient ceramics) exhibited the highest ?′ values (2.1x104 at 1kHz for CC2.9T3.75O ceramic). Also, CT/deficient ceramics showed lower tanδ values (0.090 at 1kHz for CC2.9T3.75O ceramic) than ceramics prepared with excessive CuO–TiO2 phase (0.241 at 1kHz for CC3.1T4.25O ceramics). The deficiency of CuO and TiO2 phases associated with high percentage of CCTO and CaTiO3 phases resulted in ceramics with the higher ?′ values.
关键词： CaCu3Ti4O12,titanates,dielectric materials properties,microstructure
更新于2025-09-10 09:29:36
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Role of reduced graphene oxide in dielectric enhancement of ferroelectric polymers composites
摘要： Flexible polymer composites with high dielectric constant are highly desirable for electrical and electronic applications. This work demonstrated the preparation of high-dielectric-constant (high-k) and low-dielectric-loss flexible composites by incorporating reduced graphene oxide (rGO) and the colossal-dielectric-constant CaCu3Ti4O12 (CCTO) particles in poly(vinylidene fluoride) matrix via solution processing. The three-phase composites combine the merits of each two-phase composite while avoiding the demerits of the two-phase composites. A high dielectric constant (～40.4) and relatively low dielectric loss tangent (～0.08) at 1 kHz were achieved when rGO and functionalized CCTO were 0.61 vol% of 12.5 vol%, respectively. The enhanced dielectric properties of the composites may originate from both induced polarization effect and intrinsic high dielectric constant of rGO, and the tunneling effect between rGO sheets play an important role in electrical conductivity and dielectric loss of the composites. It is believed that the ceramic/rGO/polymer three-phase hybrid strategy can be used to design and fabricate high-k composites with desirable flexibility and dielectric applications.
关键词： poly(vinylidene fluoride),CaCu3Ti4O12,reduced graphene oxide,dielectric constant
更新于2025-09-09 09:28:46