Calcium Copper Titanate CaCu3Ti4O12 Research Articles

Calcium copper titanate incorporated polydimethylsiloxane flexible composite film-based triboelectric nanogenerator for energy harvesting and self-powered sensing applications

Triboelectric energy harvesters offer an efficient way to convert mechanical energy harvested by everyday human body actions into electrical energy. Triboelectric nanogenerators (TENGs) are an attractive solution for power supply concerns in the development of portable electronic gadgets and self-powered sensor applications. Herein, a dielectric calcium copper titanate (CaCu3Ti4O12 (CCTO)) ceramic material was synthesized by a solid-state reaction process. The synthesized particles were embedded in polydimethylsiloxane (PDMS) polymer to form a CCTO/PDMS flexible composite film (FCF)-based TENG, called a CCTO FCF-TENG, which is light-weight, simple, and suitable for use. The dielectric properties, surface charge density, and electrical conductivity of the FCF were greatly improved by the addition of the CCTO particles into the PDMS, resulting in excellent electrical output performance of the corresponding CCTO FCF-TENG. The CCTO FCF-TENG device was constructed with the CCTO/PDMS FCF, which functioned vertically against a cellulose paper to optimize a high and stable electrical output. Furthermore, the filler concentration and film thickness optimization was studied more to achieve the highest output power of the CCTO FCF-TENG. The optimized CCTO FCF-TENG exhibited the highest electrical output voltage, current, charge density, and power density of ∼250 V, ∼6.5 μA, ∼70 μC/m2, and ∼3.15 W/m2, respectively. The mechanical stability and durability of the CCTO FCF-TENG were systematically analyzed. The practical and real-time applications of the packed CCTO FCF-TENG were systematically investigated under various harsh environmental conditions. Finally, the packed CCTO FCF-TENG successfully powered several low-power portable electronics and was also used as a self-powered sensor to sense biomechanical actions in everyday human body activities.

Degradation of organic dyes by utilizing CaCu3Ti4O12 (CCTO) nanoparticles via tribocatalysis process

Tribocatalysis is an emerging catalysis process which leverages the triboelectric effect, wherein the interaction between two dissimilar materials through friction yields charges capable of promoting diverse catalytic reactions. The current study utilized Calcium Copper Titanate, CaCu3Ti4O12 (CCTO) nanoparticles as a tribocatalyst to degrade a cationic organic dyes Methylene blue (MB) and Rhodamine Blue (RB). Tribocatalysis, a promising catalytic process, was conducted for a duration of 12 hours using a glass beaker and Polytetrafluoroethylene (PTFE)/Teflon. The degradation process was observed at different stirring speeds of Teflon, namely 300, 500, and 700 rpm for MB dye. The results indicated that as the stirring speed of Teflon increased, there was a corresponding increase in the degradation of MB dye. The maximum degradation achieved within the 12-hour was approximately 78% at a stirring speed of 700 rpm whereas approximately 60% of RB dye was degraded at same speed. Furthermore, stability of CCTO ceramic was maintained even after utilizing it for 4 consecutive cycles for both MB and RB dye. With the outcomes of the present study, it can be said CCTO nanoparticles possess the ability to harness mechanical energy from the surrounding, utilizing friction as a means to remove contaminants from water.

Effects of Ferroelectric Fillers on Composite Dielectric Elastomer Actuator

Integrating nano- to micro-sized dielectric fillers to elastomer matrices to form dielectric composites is one of the commonly utilized methods to improve the performance of dielectric elastomer actuators (DEAs). Barium titanate (BaTiO3) is among the widely used ferroelectric fillers for this purpose; however, calcium copper titanate CaCu3Ti4O12 (CCTO) has the potential to outperform such conventional fillers. Despite their promising performance, CCTO-based dielectric composites for DEA application are studied to a relatively lower degree. Particularly, the composites are characterized for a comparably small particle loading range, while critical DEA properties such as breakdown strength and nonlinear elasticity are barely addressed in the literature. Thus, in this study, CCTO was paired with polydimethylsiloxane (CH3)3SiO[Si(CH3)2O]nSi(CH3)3 (PDMS), Sylgard 184, to gain a comprehensive understanding of the effects of particle loading and size on the dielectric composite properties important for DEA applications. The dielectric composites’ performance was described through the figures of merit (FOMs) that consider materials’ Young’s modulus, dielectric permittivity, and breakdown strength. The optimum amounts of the ferroelectric filler were determined through the FOMs to maximize composite DEA performance. Lastly, electromechanical testing of the pre-stretched CCTO-composite DEA validated the improved performance over the plain elastomer DEA, with deviations from prediction attributed to the studied composites’ nonlinearity.

New approach for synthesis of nano-sized CaCu3Ti4O12 powder by economic and innovative method

In this work, calcium carbonate (CaCO3), copper oxide (CuO) and titanium oxide (TiO2) were used as precursors to synthesize nano-sized calcium copper titanate CaCu3Ti4O12 (CCTO) powder using environmental friendly and modified sonochemical-assisted process. The precursor mixtures were sonicated at 80 °C for 4 h to get a fully precipitated and homogenous product. A pure phase of CCTO powder was obtained at 900 °C. Various techniques were employed to study the phase formation and structural aspects of the calcined CCTO such as XRD, FTIR, HRTEM, TGA and dielectric spectroscopy. The XRD results confirm the formation single phase with cubic structure of the CCTO phase. The absorption bands in FTIR at 400–700 cm−1, which arise from the mixed vibrations of CuO4 and TiO6 groups, are prevailing in the CCTO structure. Moreover, the HR-TEM micrographs reveal a highly oriented single cubic crystal structure of particle size ~ 4.78 nm. In addition, the dielectric study discloses that the dielectric constant e′ increased with increasing the calcination temperature up to 900 °C escorted by a decrease of loss factor (tanδ). This can be attributed to the formation of pure CCTO phase and the highly dense microstructure at high temperatures. Giant dielectric constant e′ up to (106–105) exhibited at low frequency (1–1000 Hz). It is deduced that the optimum calcination temperature of the prepared CCTO must not exceed the temperature range (800–900 °C). Furthermore, the prepared CCTO nanopowder is a promising material for energy storage applications.

Synthesis of CCTO and Doped CCTO Nanopowders and its Applications in the Field of Electronics

Demand for miniaturization of electrical and electronic devices has raised a challenge for development of capacitors with large dielectric constant and low dielectric loss. Calcium Copper Titanate, CaCu3Ti4O12 (CCTO) possess high dielectric constant, which has attracted much attention for the development of capacitors materials for electronic industries. CaCu3Ti4O12 (CCTO) and MgTiO3 Nano powders was synthesized in this work by applying Co-precipitation method followed by sintering of CCTO at 800°C and MgTiO3 at 600°C for 1h, sintering processes were employed in order to improve phase structures, morphology and dielectric properties. The microstructure, structural morphology of CCTO and MgTiO3 has been studied by XRD and SEM. Then CCTO/ MgTiO3 composites was prepared using CCTO and MgTiO3 Nano powders, then the dielectric properties of composites was studied using impedance spectroscopy.

Dielectric and thermal properties of CCTO/epoxy composites for embedded capacitor applications: mixing and fabrication methods

In this study, calcium copper titanate, CaCu3Ti4O12 (CCTO) was used as filler in epoxy composite using different mixing and fabrication methods to investigate their suitability as dielectric materials for embedded capacitor. Results show that 20 vol% CCTO/epoxy composite produced using ultrasonic mixing method yield slightly higher dielectric constant, T 5% and T onset as compared to 20 vol% CCTO/epoxy composite produced using agate mortar method. Meanwhile, sample with 20 vol% CCTO/epoxy composite fabricated using spin coating method shows slightly higher dielectric constant, T 5%, T onset and E′, and lower CTE value compared to 20 vol% CCTO/epoxy composite fabricated using hot press method. Nevertheless, 40 vol% CCTO/epoxy composite fabricated using hot press method shows the highest dielectric constant, T 5%, T onset and E′, and lowest CTE value compared to all composites. In short, composite produced using ultrasonic as mixing method and spin coating as fabrication method are suitable to be utilized to produce epoxy composite as dielectric materials for embedded capacitor applications.

Dielectric properties and thermal properties of calcium copper titanate and barium titanate hybrid fillers filled epoxy thin film composites for electronic packaging applications

Ceramic fillers such as calcium copper titanate, CaCu3Ti4O12 (CCTO) and barium titanate (BaTiO3) were used as hybrid fillers to produce hybrid thin film composites for electronic packaging applications. Results indicated that positive hybrid effect in dielectric and thermal properties showed by the hybrid composites. Hybrid fillers with the ratio of 70:30 of CCTO:BaTiO3 filled epoxy thin film composite exhibited the highest dielectric constant, lowest coefficient thermal expansion value, moderate thermal stability and dynamic mechanical properties compared to those of hybrid composites with the ratio of 30:70 and 50:50, unfilled epoxy, 20 CEC and 20 BEC, respectively.

Properties of calcium copper titanate and barium titanate filled epoxy composites for electronic applications: effect of filler loading and hybrid fillers

Inorganic ceramics such as calcium copper titanate, CaCu3Ti4O12 (CCTO) and barium titanate (BaTiO3) were used as fillers to produce epoxy thin film composites for capacitor application. The effects of filler types and loading range on the dielectric, tensile, morphology, and thermal properties of the epoxy thin film composites were determined. Results showed that epoxy thin film composites with 20 vol% filler loading of CCTO and BaTiO3 showed good dielectric properties, thermal stability, and thermal conductivity. However, the tensile properties of the CCTO/epoxy thin film composite was reduced as the filler loading increased. On the other hand, the tensile properties of BaTiO3/epoxy thin film composite improved as the filler loading increased. Hybrid fillers CCTO and BaTiO3 filled epoxy composites were fabricated and the effect of hybrid fillers on the dielectric properties and morphology of the epoxy thin film composites were investigated. Results indicated that positive hybrid effect in dielectric constant and dielectric loss showed by the hybrid composites.

Leading role of grain boundaries in colossal permittivity of doped and undoped CCTO

Abstract The role of grain boundaries in the colossal permittivity ɛ of doped and undoped calcium copper titanate, CaCu3Ti4O12 (CCTO), is illustrated by a first correlation – over four orders of magnitude – between ɛ and the capacity of grain boundaries, not that of grains, deduced from the analysis of impedance measurements. The DC resistance of the CCTO sample which is essential to make efficient capacitors for technological applications, as well as the loss factor tan(δ), are found to be correlated with the resistance of the grain boundaries rather than that of the grains. The correlation extends over almost seven orders of magnitude. These findings, consistent with the internal barrier layer capacitance (IBLC) model, indicate the leading role of grain boundaries in the origin of the capacitance of CCTO samples.

Dielectric behavior of CaCu3Ti4O12 electro-ceramic doped with La, Mn and Ni synthesized by modified citrate-gel route

The effect of La3+, Mn2+ and Ni2+ doped calcium copper titanate, CaCu3Ti4O12 (CCTO), at higher concentrations (CR1 and CR2 with 5 mol% and 10 mol%, respectively), has been examined by semi-wet route at relatively lower temperature. This semi-wet route employs citrate-nitrate gel chemical method using TiO2 solid powders. X-ray diffraction (XRD) analysis confirms the formation of single phase in the doped samples sintered at 900 °C for 8 h. Scanning electron micrographs (SEM) show that the average grain size for CR2 is larger than that of CR1 composition. The energy dispersive X-ray spectroscopy (EDX) is used to study the percentage compositions of different ions present in both ceramics. Dielectric constant (ɛr) and dielectric loss (tanδ) values of CR1 are comparatively higher than those of CR2 ceramic at all measured frequencies and temperatures. The nature of temperature-dependent relaxation behavior of the ceramics is also studied by impedance, modulus spectroscopic analysis and confirms Maxwell-Wagner relaxation.

Influence of Zn doping on microstructures and dielectric properties in CaCu3Ti4O12 ceramic synthesised by semiwet route

A single phase of calcium copper titanate [CaCu3Ti4O12 (CCTO)] was produced at lower temperature and shorter calcination time via a novel semiwet route. Undoped CCTO and zinc doped CaCu3−xZnxTi4O12 samples with x = 0·10, 0·20 and 0·30 were prepared by this method for the first time using solid TiO2 powder in metal nitrate solutions. The CaCu3−xZnxTi4O12 ceramics were characterised by thermogravimetric/differential thermal analysis, X-ray diffraction, SEM and EDX techniques. The SEM images of the sintered CaCu3−xZnxTi4O12 ceramics showed average grain size in the ranges of 2–6, 8–13, 12–16 and 14–20 μm for x = 0·00, 0·10, 0·20 and 0·30 respectively. Energy dispersive X-ray spectroscopy studies confirm the purity of parent and Zn doped CCTO ceramics. At room temperature, the dielectric constants of Zn doped CCTO are always higher than pure CCTO. CaCu3−xZnxTi4O12 (x = 0·20) ceramic has the maximum value of ϵr≈4347 along with the minimum value of tan δ≈0·14 at 1 kHz.

Electronic Structure of Bulk and Defected CaCu3Ti4O12

The calcium copper titanate CaCu3Ti4O12 is a distorted perovskite exhibiting a giant dielectric constant with non-ferroelectric temperature behavior. Recent investigations tend to attribute the origin of the anomalous behavior of CaCu3Ti4O12 dielectric properties to the presence of heterogeneous microstructure and grain boundary layers, excluding that the giant dielectric constant is present in perfectly stoichiometric, defect-free crystals. The intrinsic origin is also ruled out by the normal dielectric behavior obtained in ab initio Density Functional Theory (DFT) calculations. In this work, we present ab initio calculations performed to estimate the energies associated with the creation of defects in the CaCu3Ti4O12 lattice, including oxygen and copper vacancies, and investigate their electronic properties. Furthermore, with a view at ascertaining whether correlation effects may modify the electronic structure and dielectricity of CaCu3Ti4O12, we present an application to CaCu3Ti4O12 of a DFT-based pseudo-selfinteraction-correction (pSIC) method already applied successfully to Mott insulators.