Dielectric Properties of Ca0.7Bi0.3Ti0.7Cr0.3O3 (CBTC)–CaCu3Ti4O12 (CCTO) Composite (original) (raw)
Related papers
Materials Characterization, 2014
BaTiO 3 (BTO), CaCu 3 Ti 4 O 12 (CCTO) and 0.5BaTiO 3 •0.5CaCu 3 Ti 4 O 12 (BTO-CCTO), as a new nano-composite ceramic, were successfully designed and fabricated by a semi-wet gel route and a modified solid state method. The dielectric properties of the BTO-CCTO ceramic were compared to those of the BTO and CCTO ceramics at lower sintering temperatures and durations. The X-ray diffraction analysis revealed that the BTO and CCTO ceramics form a single crystalline phase and the average crystalline sizes calculated from X-ray diffraction data were in the range of 40-65 nm. The particle sizes of the BTO, CCTO, and BTO-CCTO ceramics obtained from transmission electron microscopy images were in the ranges of 40-65 nm, 80-110 nm, and 70-95 nm, respectively. The phase composition and microstructure were studied by X-ray diffraction and scanning electron microscopy. The energy dispersive X-ray results demonstrated the purity and stoichiometry of the BTO-CCTO nano-composite. The grain sizes of the BTO, CCTO and BTO-CCTO ceramics were found to be in the ranges of 500 nm-1 μm, 4-24 μm, and 250 nm-4 μm, respectively. The AC conductivity as a function of frequency confirmed the semiconducting nature of all of the ceramics and obeyed the Jonscher's power law. The impedance spectrum measurement result showed that the CCTO ceramic possessed an exceptional grain boundary resistance, which supports the internal barrier layer capacitance (IBLC) mechanism present in this ceramic and is responsible for the high ε r values.
Mediterranean Journal of Chemistry
In this paper, composite ceramics (1-x)CaCu3Ti4O12–(x)PbZr0.48Ti0.52O3 (with x =0.00, 0.50 and 1.00), denoted CCTO-PZT, were prepared by a three-stages modified method, in order to achieve high dielectric constant and low loss. Structural investigations carried out by X-ray diffraction (XRD), and FT-IR spectroscopy showed the formation of pure cubic and tetragonal phases for x = 0.00 and x=1.00 compositions, respectively. XRD showed the coexistence of both phases in the CCTO-PZT composite. The morphology of the ceramics was examined by scanning electron micrograph (SEM), results reveal a homogeneous microstructure with two types of grains corresponding to PZT (smaller grains) and CCTO (large grains). Dielectric measurements carried out by an impedance analyzer; show that the dielectric constant of the CCTO-PZT composite is higher than the pure samples (CCTO and PZT) one. The temperature dependence of the ac conductivity indicated that the conduction follows the Arrhenius law and the...
Mediterranean Journal of Chemistry, 2019
In this paper, composite ceramics (1-x)CaCu3Ti4O12–(x)PbZr0.48Ti0.52O3 (with x =0.00, 0.50 and 1.00), denoted CCTO-PZT, were prepared by a three-stages modified method, in order to achieve high dielectric constant and low loss. Structural investigations carried out by X-ray diffraction (XRD), and FT-IR spectroscopy showed the formation of pure cubic and tetragonal phases for x = 0.00 and x=1.00 compositions, respectively. XRD showed the coexistence of both phases in the CCTO-PZT composite. The morphology of the ceramics was examined by scanning electron micrograph (SEM), results reveal a homogeneous microstructure with two types of grains corresponding to PZT (smaller grains) and CCTO (large grains). Dielectric measurements carried out by an impedance analyzer; show that the dielectric constant of the CCTO-PZT composite is higher than the pure samples (CCTO and PZT) one. The temperature dependence of the ac conductivity indicated that the conduction follows the Arrhenius law and t...
Effect of Boron Addition on the Dielectric Properties of Giant Dielectric CaCu3Ti4O12
Ferroelectrics, 2005
The recently discovered giant dielectric CaCu 3 Ti 4 O 12 (CCTO) has been reported to show dielectric constant value as high as 80,000 for single crystals and around 10,000 for ceramics. However the dielectric constant is also associated with high dissipation factor. In the present study, it has been observed that the loss factor of CCTO can be reduced by B 2 O 3 addition. The low frequency dispersion of CCTO ceramics, which indicates Maxwell-Wagner type relaxation, is reduced by boron addition. Also the temperature dependence of dielectric constant is minimized by boron addition. From the present work it can be surmised that B 2 O 3 addition can favourably modify the dielectric properties of CCTO ceramic for its practical applications as a capacitor material.
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.
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.
Materials
CaCu3Ti4-x((A0.05Nb0.05))xO12 ceramics (A: Al and Bi; x = 0, 0.3) were synthesized by high-energy mechanical ball milling and reactive sintering at 1050 °C in air. Rietveld refinement of XRD data revealed the pure and (Al3+, Nb5+) cosubstituted ceramics contained a minor CuO secondary phase with a mole fraction of about 3.2% and 6.9%, respectively, along with a CaCu3Ti4O12 (CCTO)-like cubic structure. In addition, (Bi3+, Nb5+) cosubstituted ceramics had a pyrochlore (Ca2(Ti, Nb)2O7) secondary phase of about 18%. While the (Al3+, Nb5+) cosubstituted CCTO showed the highest relative permittivity (ε’ = 3.9 × 104), pure CCTO showed the lowest dielectric loss (tanδ = 0.023) at 1 kHz and 300 K. Impedance-spectroscopy (IS) measurements showed an electrically heterogeneous structure for the studied ceramics, where a semiconducting grain was surrounded by highly resistive grain boundary. The giant relative permittivity of the ceramics was attributed to the Maxwell–Wagner polarization effect ...
Dielectric properties of CCTO/MgTiO3 composites: A new approach for Capacitor application
In this work, first, single phase CaCu3Ti4O12 (CCTO) and MgTiO3 were synthesized by sol gel and solid state method respectively and then (1-x) CaCu3Ti4O12-x MgTiO3 (x = 0, 1,3 and 5 weight%) composites were prepared by a conventional mixed oxide method using CCTO and MgTiO3 single phase powders. The characterization for phase identification was done by X-Ray diffraction, for surface morphology, scanning electron microscope was used. Raman measurements were done to identify the nature of grain and grain boundaries. CuO was identified as a main component of grain boundary. The dielectric and resistivity properties of CaCu3Ti4O12/ MgTiO3 composites were investigated. The results revealed that mixed phase samples can improve both dielectric and resistivity properties. The low frequency (<10 5 Hz) loss tangent was greatly reduced(<0.2 for 1 % mixed sample); while, the dielectric constant was found to be higher than 3.0×10 6 at room temperature (RT). The nature of CCTO/MgTiO3 compos...
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...
Journal of Alloys and Compounds, 2017
The CaCu 3 Ti 4 O 12 ceramic, CCTO, remains as the best material due to its high dielectric constant. In this context, Sr-doped CCTO, Ni-doped CCTO and Sr,Ni co-doped CCTO ceramics were prepared by the solid-state reaction method and were sintered at 1100°C for 24 h in order to enhance the geometric microstructure and dielectric properties. X-ray diffraction data refined via rietveld method for CaCu 3 Ti 4 O 12 confirms the formation of single phase. SEM micrographs revealed that the substitution of Sr 2+ and/or Ni 2+ on Ca and Cu sites respectively increase the grain size of CaCu 3 Ti 4 O 12 ceramics. Raman scattering measurements shows the presence of TiO 2 phase at grain boundaries, which is an important parameter to reduce the dielectric loss of samples. It is found that Sr,Ni co-substitution in CCTO leads to the best dielectric measurements at low frequency. The highest grain boundary resistance value is also obtained for co-doped CCTO sample in the order of 1.84 10 6 Ω. This value is 10 times higher than pure CCTO. Meanwhile, the nonlinear coefficient values were improved, whereas, the breakdown electric field and leakage current decreased for all ceramic samples and co-doped CCTO is considered as the best conductive grain and insulating grain boundary.