Dielectric Constant of nano- CCTO / Epoxy Composit (original) (raw)
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Dielectric Constant of nano-CCTO / Epoxy Composite
Nanocrystalline multiphase CaCu 3 Ti 4 O 12 (CCTO) was prepared using Ca(NO 3 ) 2 .4H 2 O, Cu(NO 3 ) 2 .3H 2 O, TiO 2 and C 2 H 2 O 4 .2H 2 O. The X-Ray differection and SEM analysed of the prepared CCTO powder sintered at 900 o C and 950 o C.
Dielectric studies of CCTO-based nanocomposite ceramic synthesized by a solid state route
International Journal of Materials Research, 2018
In the present work, the nanocomposite 0.9CaCu3Ti4O12–0.1BaTiO3 (CC-BT) is synthesized by a solid-state reaction method by sintering at 950°C for 12 h. X-ray diffraction analysis confirms the presence of both BaTiO3 and CaCu3–Ti4O12 phases in the composite ceramic. Transmission electron microscopy analysis of the composite demonstrates the formation of nanoparticles with an average particle size of 40 ± 5 nm. The surface morphology of the composite sintered at 950°C for 12 h obtained by scanning electron microscopy analysis indicates the evolution of large and small grains with a bimodol distribution. The average and root mean square roughness were found to be 1.41 nm and 2.24 nm respectively by atomic force microscopy studies. The dielectric constant of CC-BT ceramic was determined to be 6231 at 100 Hz and 500 K. The presence of the semiconducting grains and the insulating grain boundaries in the composite supports the internal barrier layer capacitance mechanism operative in CC-BT...
Dielectric behaviour of CaCu3Ti4O12-epoxy composites
Materials Research-ibero-american Journal of Materials, 2008
The dielectric behavior of composite materials (epoxy resin -barium titanate and epoxy -CCTO) was analysed as a function of ceramic amount. Composites were prepared by mixing the components and pouring them into suitable moulds. In some compositions, the matrix was reduced by tetrahydrofuran (THF) incorporation. Samples containing various amounts of ceramic filler were examined by TG/DTA and scanning electron microscopy analysis. Dielectric measurements were performed from 20 Hz to 1 MHz and 30 to 120 °C. It was demonstrated that the epoxy -CCTO composites possessed higher permittivity than classic epoxy -BaTiO 3 composites. However, the low resin permittivity prevailed in the composite dielectric performance.
Dielectric Properties of CaCu 3 Ti 4 O 12 (CCTO) Prepared by Modified Solid State Reaction Method
In this paper, an attempt has been made to study dielectric properties of CaCu 3 Ti 4 O 12 (CCTO) ceramics. For this, CaCu 3 Ti 4 O 12 was prepared by the modified solid state reaction method. The dielectric constant (ε') and dielectric loss (tan δ = ε''/ε') were measured within the frequency range from 10 2 Hz to 10 6 Hz and the temperature ranging from 30°C to 300°C using HP 4192A LF Impedance Analyzer. The results showed that the dielectric constant and dielectric loss of the sample are frequency and temperature dependent. Dielectric constant and dielectric loss increases with decreasing frequency and increasing temperature due to interfacial polarization.
Ceramics International, 2019
Polyaryletherketone (PAEK)/CaCu 3 Ti 4 O 12 (CCTO) nanocomposite films with various (0, 1, 5, 10 and 20) weight% CCTO were fabricated via melt-compounding followed by film extrusion process. The CCTO nanoceramics (nCCTO) with a crystallite size around 30-100 nm were prepared from oxalate precursor route. The thickness of the fabricated films was in the range of 50-80 µm and these films were characterized for their structural, thermal and dielectric behavior. The X-ray diffraction analyses showed the presence of peaks corresponding to both PAEK and CCTO with varying intensities. Fourier transform infrared (FTIR) studies revealed that the chemical structure of PAEK was unaltered by the incorporation of nCCTO. Melting temperature of the pure PAEK was about 372 °C and had not changed significantly with the addition of nCCTO. Thermo-gravimetric analysis was carried out to study the thermal stability of these nanocomposites. Frequency independent dielectric behavior was observed in case of all nanocomposite films. Room temperature dielectric permittivity of PAEK (3.3 at 10 kHz) was enhanced with the addition of nCCTO and for 20 wt% loading a value of 4.5 has been achieved. Low values of dielectric loss (0.005-0.009) were obtained for all nanocomposite films at 10 kHz. These nanocomposites can be explored as possible dielectric materials for capacitor applications.
Bulletin of Materials Science, 2020
Epoxy (LY-556/HY-951) system was cured at ambient temperature and its copper cobaltite nanocomposites with different percentage loadings of nanoparticles were prepared via powered shear mixing with HY-951 (triethylene-tetraamine, TETA) hardener. Characterizations of the nanocomposites were done by various methods like XRD, TEM, FTIR, TGA, DSC, SEM, VNA, DETA and XPS. XRD, XPS and TEM showed the successful preparation of copper cobaltite nanoparticles. Further, FTIR studies confirmed accomplishment of curing and consequently the formation of cross-linked network in the nanocomposites. The morphological analysis revealed that the nanoparticles of the copper cobaltite were uniformly distributed inside the epoxy matrix to 5% loading. The enhancement in impact properties of nanocomposites with increase in filler content was supported by fractured surface studies for even distribution of copper cobaltite nanoparticles. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analyses showed enhancement in thermal stability as well as positive shift in the glass transition temperature for epoxy with copper cobaltite filler in comparison to neat epoxy resin. The positive shift in the glass transition temperature of the nanocomposites indicated improved interaction between copper cobaltite and epoxy matrix. These nanocomposites were also evaluated for their electromagnetic properties using dielectric thermal analyzer (DETA) and vector network analyzer (VNA) for determination of their permittivity and permeability, respectively. The improved thermal, mechanical and electromagnetic properties of epoxy-copper cobaltite nanocomposites make them potential candidates for microwave applications in a wide range of areas.
Ceramics International, 2019
In this research, the dielectric and non-Ohmic properties of nano/micro-sized CaTiO 3 /CaCu 3 Ti 4 O 12 composites (NCTO/MCCTO) with different weight percent of CTO (0, 7, 15, and 30 wt%) were examined as a new engineering design. NCTO was prepared after high energy ball milling of calcined CaCO 3 and TiO 2 mixture. Microsized CCTO was synthesized after calcination of CaCO 3 , CuO, and TiO 2 mixture at 1000°C. According to the TEM, BET, and SEM analyses; the mean particle size of NCTO and MCCTO was 80 nm and 2.5 μm, respectively. The NCTO/MCCTO powder composites were prepared from direct mixing of pre-synthesized NCTO and MCCTO. After the sintering of green body composites at 1100°C for 5 h, both relative density and grain size of NCTO/ MCCTO composites decreased with the increase in NCTO content. It was found that the abnormal grain growth in the sintered MCCTO changed to the normal grain growth in NCTO/MCCTO composites. The best dielectric properties (ϵ r : 7050, tanδ: 0.02) was observed for NCTO/MCCTO with 15 wt% CTO. This unique dielectric constant was ascribed to the large grain size of CCTO, and the reduced dead zone of CTO with a low dielectric constant. Due to uniform distribution of CTO with the small size of 0.3-1.5 μm at grain boundaries of CCTO with a large grain size of 5 μm, the number of active interfaces were increased sharply and consequently the maximum breakdown electric field of 7 kV/cm and the nonlinear coefficient of 15 were obtained for NCTO/MCCTO with 15 wt% of NCTO. Therefore, the MCCTO-NCTO composite with 15 wt% of NCTO is a promising candidate for the capacitor and energy storage applications.
Thermal and dielectric performance of Melt processed Polycarbonate /CaCu 3 Ti 4 O 12 composites
Composites comprising Polycarbonate (PC) and CaCu 3 Ti 4 O 12 (CCTO) were fabricated via melt mixing followed by hot pressing by employing both micron (1-7µm) and Nano (75-100 nm) sized crystallites of CCTO. Both the micro and Nano CCTO powders were self-synthesized using solid state and co-precipitation routes respectively.These were characterized using X-ray Diffraction (XRD), Thermo Gravimetric (TGA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM),Impedance analyzer for their structural, morphology and dielectric properties. Nanocomposites inducted with nCCTO-50 wt% exhibited better thermal stability than that of pure PC and composite embedded with micron sized CCTO. However, there was no significant difference in the glass transition (T g) temperature between the polymer and the composites. The Nano composites (PC+nCCTO-50 wt%) exhibited 2.5times higher permittivity values as compared to that of composites having 50 vol% micron sized CCTO crystallites.
Process and Microstructure to Achieve Ultra-high Dielectric Constant in Ceramic-Polymer Composites
Scientific Reports, 2016
Influences of process conditions on microstructure and dielectric properties of ceramic-polymer composites are systematically studied using CaCu3Ti4O12 (CCTO) as filler and P(VDF-TrFE) 55/45 mol.% copolymer as the matrix by combining solution-cast and hot-pressing processes. It is found that the dielectric constant of the composites can be significantly enhanced–up to about 10 times – by using proper processing conditions. The dielectric constant of the composites can reach more than 1,000 over a wide temperature range with a low loss (tan δ ~ 10−1). It is concluded that besides the dense structure of composites, the uniform distribution of the CCTO particles in the matrix plays a key role on the dielectric enhancement. Due to the influence of the CCTO on the microstructure of the polymer matrix, the composites exhibit a weaker temperature dependence of the dielectric constant than the polymer matrix. Based on the results, it is also found that the loss of the composites at low temp...
Dielectric Properties of Nylon 11/CaCu 3 Ti 4 O 12 (CCTO) Nanocomposite Films with High Permittivity
2019
Flexible nylon 11/CaCu 3 Ti 4 O 12 (CCTO) nanocomposite films (thickness ~100 μm) with varying CCTO nanoceramics (0 to 30 wt%) were fabricated by solution casting method followed by vacuum drying. The nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy, and impedance analyzer to study their structural and dielectric properties. XRD analysis revealed the presence of γ-phase of nylon 11 both in as-cast film as well as in the composites. SEM micrographs indicated that the CCTO nanocrystals were distributed evenly throughout the nanocomposite films with less agglomeration. The room temperature dielectric permittivity was 168 at 50 Hz when the CCTO content increased to 30 wt% in the polymer and this was increased to 1007 at 423 K. Frequency independent dielectric behavior was observed for the frequency range of 100 kHz-10 MHz. Temperature coefficient of permittivity showed that the permittivity of the nanocomposites is highly temperature dependent.