Addition Of CaTiO3 Research Articles

Optimising thermochemical energy storage: a comprehensive analysis of CaCO3 composites with CaSiO3, CaTiO3, and CaZrO3.

With the increasing amount of renewable energy produced, many governments and industries are pushing for the installation of battery energy storage system (BESS) solutions. Thermal batteries are systems that store heat made from various energy sources, and can be used to produce electricity upon demand. These systems are easily scalable and can be installed in cities, homes and remote locations. Thermochemical energy storage (TCES) uses the enthalpy of a chemical reaction to store and release heat through endothermic and exothermic processes, respectively. CaCO3 has been identified as an ideal TCES material as it is cheap and abundant, but maximising long-term cyclability is key to ensure battery longevity. This article investigates the addition of CaSiO3, CaTiO3 and CaZrO3 to CaCO3 in a 1 : 1 ratio to ascertain the reaction properties and cyclic capacity over time. Cycling longevity and thermodynamic properties were determined using simultaneous differential scanning calorimetry and thermogravimetric analysis (DSC-TGA) along with the Sieverts technique, and their reaction pathway studied by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The low cost of the CaCO3-CaSiO3 material of $1.8 USD per kW hth suggests that if a suitable particle refinement agent were to be employed to ensure cycling longevity this material would be an excellent TCES material. Despite the CO2 cycling capacity of the CaCO3-CaZrO3 system only reducing by 16 wt% over 100 cycles, the cost of ZrO2 brings the materials cost to $30.9 USD per kW hth, making this material currently unsuitable for application. The CaCO3-CaTiO3 system showed only a 17% drop in total CO2 uptake over 100 cycles, although the cost was $11.1 USD per kW hth.

Sintering behavior, crystal structure, and microwave dielectric properties of a novel diopside SrMgGe2O6 ceramic and adjustment of its τf value

A solid-state process was used to synthesize novel microwave dielectric SrMgGe2O6 ceramics. X-ray diffractometry revealed that these ceramics have monoclinic structures that belong to the C2/c space group. A dense SrMgGe2O6 ceramic was obtained at the optimal sintering temperature of 1225 °C, the ceramic exhibited excellent microwave dielectric properties, with εr = 8.58, Q×f = 56800 GHz, and τf = −59.06 ppm/°C. The τf value is affected by the bond valence and bond energy of the Ge–O bond. The addition of CaTiO3 or TiO2 successfully adjusted the τf value to approximately zero, with the optimal CaTiO3- and TiO2-included composite ceramics exhibiting excellent dielectric properties, with εr = 11.74, Q×f = 22056 GHz, τf = +0.18 ppm/°C, and εr = 12.32, Q×f = 20930 GHz, τf = −2.27 ppm/°C, respectively.

Magnetic and dielectric properties of low-temperature sintered NiCuZn/CaTiO3 composite dual-performance materials

The effect of CaTiO3 addition on the sintering behavior, microstructure, and magnetic and dielectric properties of NiCuZn/CaTiO3 composite dual-performance materials was investigated. The crystal and microstructure were characterized by X-ray diffraction and scanning electron microscopy. The magnetic and dielectric properties were obtained by vibrating sample magnetometry and impedance analysis. The CaTiO3 ceramic could coexist with the NiCuZn ferrite. The atom substitution occurred in the composite materials, and the increment in CaTiO3 content led to a gradual decline in grain size of NiCuZn ferrite. The saturation magnetization and permeability decreased gradually as CaTiO3 content increased, while the coercivity increased gradually. Meanwhile, the cut-off frequency and dielectric constant of the composite materials incremented, and all samples presented optimized performance with the increased sintering temperature. The NiCuZn/CaTiO3 composite duel-performance materials exhibited excellent dielectric and magnetic properties. All in all, the addition of CaTiO3 weakened the magnetic properties of the dual-performance material, while its dielectric properties were enhanced. These results would be useful for further study on NiCuZn/CaTiO3 composite dual-performance materials.

Influence of the addition of CaTiO3 on the microwave dielectric properties of the BaMoO4 matrix

This work presents the study of the dielectric properties in the microwave region (MW) of BaMoO4 ceramic and composites with CaTiO3 (CTO). The BaMoO4 matrix was synthesized by solid state reaction and characterized by X-ray diffraction. Ceramic composites were obtained by adding 20–80 mol% of CTO in the BaMoO4 matrix. The Silva-Fernandes-Sombra method was used to measure the resonant frequency temperature coefficient (τf), and the BaMoO4 composite with 20% CTO showed an adequate value of relative dielectric permittivity (εr = 8.90), low dielectric loss tangent (tan δ = 9.89.10−4) and τf close to zero (τf = 3.48 ppm °C−1). BMO and its composites were applied as dielectric resonator antennas, and their far-field parameters were obtained through numerical simulation.

Polyaniline–calcium titanate perovskite hybrid composites: Structural, morphological, dielectric and electric modulus analysis

This paper reports hybrid composites based on polyaniline (PANI) and calcium titanate (CaTiO3) perovskite as a nanofiller synthesized by in-situ polymerization technique. Their structure and morphology were investigated by X-ray diffraction analysis and scanning electron microscopy. The XRD analysis shows that the addition of CaTiO3 in polyaniline reduced the amorphous structure of polyaniline transforming it into semi-crystalline nature, which agrees well with the higher conductivity. Scanning electron microscopy of composites showed a more compact and homogenous structure with uniform distribution of CaTiO3 in the polymer matrix. Dielectric parameters such as dielectric constant, loss factor, and dielectric loss, real and imaginary parts of electric modulus were measured and evaluated as a function of frequency and temperature as well. The variation of dielectric properties and ac conductivity reveals that the dispersion is due to the Maxwell-Wagner type of interfacial polarization. The observed ac conductivity behavior of polyaniline in the presence of calcium titanate was discussed in the framework of Jonscher’s power law. The result showed that ac conductivity increases with the rise of the frequency of applied field and temperature analogous to the semiconducting behavior of composites. Temperature-dependent behavior of frequency exponent seems to obey correlated barrier hopping conduction mechanism. The relaxation behavior of the synthesized samples was analyzed by the electric field modulus and was found to decrease with temperature and CaTiO3 content and increase with frequency.

Advanced tensile properties and strain rate sensitivity of titanium matrix composites reinforced with CaTiO3 particles

In the present work, a novel reinforcement, i.e., CaTiO3 particles, was adopted to produce high performance Ti matrix composites (TMCs), via a powder metallurgy process followed by hot extrusion. The results revealed that the CaTiO3 particles successfully improved the strength of Ti without sacrificing the elongation to failure. In contrast with most of ceramic particles that decompose or react with Ti matrix, CaTiO3 particles remain chemically unchanged in the matrix. Importantly, unlike titanium carbide (TiC) and other chemically stable particles that are reported with sharp corner and irregular shapes, the CaTiO3 particles display a round profile that may weaken the stress concentration in the matrix. It is found that the yield strength increases from 406 MPa for pure Ti to more than 800 MPa for TMCs with only 2.5 wt% addition of CaTiO3, while maintaining the elongation to failure over 25%. The attractive mechanical property is attributed to the hardened grain boundaries and increased geometrically necessary dislocations (GNDs) caused by the CaTiO3 particles. Besides, the experimental results show that, due to the particle-induced strong dislocation pinning and GNDs hardening effect, the strain rate sensitivity was also found increased for TMCs.

Multicycle Performance of CaTiO3 Decorated CaO-Based CO2 Adsorbent Prepared by a Versatile Aerosol Assisted Self-Assembly Method.

Calcium oxide (CaO) is a promising adsorbent to separate CO2 from flue gas. However, with cycling of carbonation/decarbonation at high temperature, the serious sintering problem causes its capture capacity to decrease dramatically. A CaTiO3-decorated CaO-based CO2 adsorbent was prepared by a continuous and simple aerosol-assisted self-assembly process in this work. Results indicated that CaTiO3 and CaO formed in the adsorbent, whereas CaO gradually showed a good crystalline structure with increased calcium loading. Owing to the high thermal stability of CaTiO3, it played a role in suppressing the sintering effect and maintaining repeated high-temperature carbonation and decarbonation processes. When the calcium and titanium ratio was 3, the CO2 capture capacity was as large as 7 mmol/g with fast kinetics. After 20 cycles under mild regeneration conditions (700 °C, N2), the performance of CO2 capture of CaTiO3-decorated CaO-based adsorbent nearly unchanged. Even after 10 cycles under severe regeneration conditions (920 °C, CO2), the performance of CO2 capture still remained nearly 70% compared to the first cycle. The addition of CaTiO3 induced good and firm CaO dispersion on its surface. Excellent kinetics and stability were evident.

Kinetics of Ca(OH)2 decomposition in pure Ca(OH)2 and Ca(OH)2-CaTiO3 composite pellets for application in thermochemical energy storage system

Thermochemical energy storage based on dehydration-hydration of Ca(OH)2/CaO reversible gas solid reaction offers an important way of understanding energy storage/release rates of energy storage system. The aim of study is to achieve better understanding of kinetics of Ca(OH)2 decomposition under isothermal conditions and to enhance reaction rate by addition of inert agent. Thermogravimetric analyzer was used to perform kinetic analysis of pure Ca(OH)2 decomposition at various temperatures, yielding kinetic parameters - activation energy and Arrhenius constant with derived rate control equations for isothermal and non-isothermal conditions. CaTiO3 is added to Ca(OH)2 at different compositions to enhance kinetic parameters in form of composite pellets which showed significant increase in activation energy and Arrhenius constant values. Addition of CaTiO3 assisted in increasing reaction rate likely by increasing reaction surface area. Composite pellets showed promising results to get new advanced hydroxide-based material however further study on cyclic stability of the material is needed.

High thermal stability of the YNbO4 − CaYTiNbO7 composites for radio frequency and microwave applications

The present work shows present the dielectric properties of YNO – CYNTO ceramic composites at Radio Frequency (RF) and Microwave (MW) regions. X-ray diffraction showed that the addition of CaTiO3 (CTO) on YNbO4 (YNO) caused the formation of the CaYTiNbO7 (CYNTO) phase. In the RF analysis, a typical universal dielectric response in the frequency of the temperature-dependent conductivity was found; the frequency-dependent AC conductivity at different temperatures indicates that the conduction process is thermally activated. Regarding the values of the temperature coefficient of capacitance (TCC) was observed a change of signal with the increment of CTO. Besides, the activation energies of composites were calculated and demonstrated an increase with addition of the CTO. In the MW range, it was observed that permittivity and dielectric loss enhance with the addition of CTO. Moreover, the addition caused the improvement of the thermal-stability of YNO where τf value for YCT5% was equal to +0.64 ppm.°C−1. The composites were analyzed as antennas presenting a reflection coefficient below - 10 dB at the resonant frequency, realized gain of 5.10–5.45 dBi, bandwidth of 129–355 MHz and radiation efficiency above 95%. The results obtained indicate that YNO – CYNTO system would be interesting candidates in microwave operating devices.

Structure and optical properties of nanocomposites based on polystyrene (PS) and calcium titanate (CaTiO3) perovskite nanoparticles

Polystyrene (PS) thin films containing 4% and 8% calcium titanate (CaTiO3) perovskite nanofiller were prepared by film casting techniques. The influence of CaTiO3 loading on the structure and optical characteristic of PS were studied by using X-ray diffraction and UV-absorption spectroscopy. The XRD analysis showed the addition of CaTiO3 into PS enhanced the formation of crystal structure and resulted in the formation of nano-crystal with a smaller diameter. The optical characterizations showed that the addition of CaTiO3 reduced the transmission and increased the reflection of PS films for UV and visible wavelength of the incident light. Absorption of pure PS films was limited to less than 270 nm, while the absorption of PS/CaTiO3 composites film covered the whole UV -range. The values of the optical energy gap were calculated by using Tauc equation. It was found that the addition of 8% CaTiO3 decreased the values of optical energy gaps from 4.42 eV to 4.26 eV. This is suggested the formation of extra energy levels in the bandgap tails, which aided the transition of electrons from the valence band to these new energy levels in the conduction band.

Structure and dielectric properties of novel series of 3CaO–RE2O3–2WO3 (RE = La, Nd and Sm) microwave ceramics and the adjustment of τf value

Using the solid-state reaction method, novel series of 3CaO–RE2O3–2WO3 (RE = La, Nd and Sm) dielectric ceramics materials were fabricated, and the crystal structure and microstructure were studied through X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The Ca3La2W2O12 (CLW) ceramic exhibited a single pure phase with a rhombohedral structure, and Ca3Nd2W2O12 (CNW) and Ca3Sm2W2O12 (CSW) ceramics had similar crystal structures with CLW. 3CaO–RE2O3–2WO3 (RE = La, Nd and Sm) ceramics are packed tightly, and the grains exhibited clear boundaries and uniform size. The CLW, CNW, and CSW ceramics sintered at 1375 °C for 4 h possessed excellent microwave dielectric properties: Ɛr = 19.1, Q × f = 34370 GHz, τf = − 80 ppm/°C; Ɛr = 19.3, Q × f = 36610 GHz, τf = − 74 ppm/°C and Ɛr = 18.8, Q × f = 23240 GHz, and τf = − 68 ppm/°C, respectively. Moreover, the (1 − x)CNW–xTiO2 (0.3 ≤ x ≤ 0.6) and (1 − y)CNW–yCaTiO3 (0.4 ≤ y ≤ 0.7) ceramics were designed and prepared to get a thermally stable material. The addition of TiO2 and CaTiO3 had a significant impact on the performances of ceramics. With increasing the TiO2 and CaTiO3 content, the relative permittivity (Ɛr) and temperature coefficient of resonance frequency (τf) values of ceramics increased, but the quality factor (Q × f) values of ceramics decreased. Especially, 0.55CNW–0.45TiO2 and 0.45CNW–0.55CaTiO3 ceramics sintered at 1375 °C for 4 h had microwave dielectric properties of Ɛr = 22.4, Q × f = 32,490 GHz, and τf = − 0.5 ppm/°C and Ɛr = 23.4, Q × f = 6440 GHz, and τf = − 1.5 ppm/°C, respectively.

Processing and Characterization of Compression Molded Multifunctional UHMWPE-CaTiO3 Composite

With increasing demand for pulse power energy storage system with high energy density has led to the development of polymer composite system that combines the processability and breakdown field strength of the polymer with the high dielectric constant of ceramic fillers. Our current research on processing polymer composites by compression molding method focuses on the enhancement of the dielectric permittivity of UHMWPE using ferroelectric metal oxides (CaTiO3). In this view, the different UHMWPE-CaTiO3 composite sheets were prepared by the addition of varying (5 and 10 wt%,) amount of CaTiO3. The microstructural characterization was carried out by using XRD, while electrical characterization of composites was carried out by Impedance Analyzer. As a result, hardness (Shore D) and apparent Density value of the UHMWPE-CaTiO3 come out to be 64 and 0.9144 g/cm3. It was also observed that with the function of frequency and temperature, the AC conductivity and dielectric constant were increased upto 3 × 10−6 S.m−1 and 2.80 respectively with addition of CaTiO3. Activation Energy was calculated using Arrhenius Equation found to be decreasing upto −3.36 × 10−9 J with increasing temperature. Finally, it can be concluded that enhancement of the electrical properties and better the interfacial adhesion between filler and the UHMWPE matrix are obtained due to addition of the CaTiO3.

Investigation of electrical and thermal property of poly(vinyl alcohol)–calcium titanate nanocomposites

The poly(vinyl alcohol):CaTiO3 nanocomposites were prepared by solution casting method using triethanolamine as a dispersive solvent in different weight percentages. The prepared nanocomposites have been characterized by FTIR and XRD for structural analysis. FTIR spectra show the important peaks of CaTiO3 and PVA which confirms the formation of nanocomposites. XRD pattern shows that the CaTiO3 has orthorhombic structure and its crystal structure does not distorted even after dispersion in PVA matrix. The TGA graph confirms that the addition of CaTiO3 (0.3 wt%) enhance the thermal stability of the nanocomposites. Further, the temperature dependent conductivity shows the increase in conductivity due to the tunnelling of charge carriers. Dielectric constant and dielectric loss of the 0.3 wt% of nanocomposites is low compare to other nanocomposites and hence its conductivity is high. It is found that the damping loss is 0.002% as indicated in quality factor and tangent loss is almost constant after 104 Hz which indicates that these nanocomposites can be used as low k-dielectric materials in electronic application.

Dielectrical and structural studies of composite matrix BiVO4–CaTiO3 and temperature effects by impedance spectroscopy

In this work, we have analysed the effects of adding CaTiO3 (CTO) and changing the temperature on the dielectric and electric properties of ceramic matrix BiVO4 (BVO) in the radiofrequency range. BVO was synthesized by a calcination process at 500 °C and ceramic composites were prepared by the addition of CTO (8, 16, 24, 28 and 32 wt%). These composites were moulded in ceramic pellets and sintered at 800 °C. The crystal structures of BVO and composites were analysed by X-ray diffraction and no spurious phase was detected in the synthesized BVO. Complex impedance spectroscopy observed the presence of a thermo-activated charge transfer process with activation energy increasing with CTO concentration in the samples. The dielectric constant (e) measured in radio frequency for ceramic composites presented high values that ranged from 26 to 9 k for BVO to BV32, respectively, at room temperature and a frequency of 1 Hz. The electrical response obtained by composites were fitted through an equivalent circuit composed of three associations in parallel with the resistance of a constant phase element, which showed minor deviations between the fitted and experimental data. The temperature coefficient of capacitance displayed negative and positive values in CTO-based composites and pure BVO, respectively; these characteristics are favourable for the application of composites in the radio frequency band.

Thermal stability, phase composition and microwave dielectric properties of (3MgO–Al2O3–3TiO2)–CaTiO3 ceramics

(1 − x)(3MgO–Al2O3–3TiO2)–xCaTiO3 (0.1 ≤ x ≤ 0.3) composite ceramics were synthesized by a conventional solid state reaction method. The effects of CaTiO3 addition on the phase composition, microstructure and microwave dielectric properties of 3MgO–Al2O3–3TiO2 ceramics were investigated. X-ray diffraction patterns showed that the composite ceramics were made up of MgAl2O4, MgTiO3, MgTi2O5, CaTiO3 and a small amount of TiO2 phases. The addition of CaTiO3 could adjust the τ f and improve the e r values of ceramics. The optimum microwave dielectric properties of e r = 17.6, Q × f = 36606 GHz and τ f = +4.63 ppm/°C were obtained for the 0.8(3MgO–Al2O3–3TiO2) – 0.2CaTiO3 ceramics sintered at 1325 °C, which indicates that this material is a suitable material for microwave devices.

Effects of CaTiO3 Loading on the Properties of PTFE/TiO2 Composites

In this paper, a detailed study was carried out on the PTFE reinforced with TiO2 and CaTiO3. The filler content of ceramic powder was a fixed value of 61 wt% and the content of CaTiO3 in PTFE matrix varied from 0 wt% to 16 wt% with a step size of 4 wt%. The effects of CaTiO3 loading on the density, moisture absorption, thermal expansion, microstructure and microwave dielectric properties were investigated. As CaTiO3 loading content increased from 0 wt% to 16 wt%, the thermal expansion initially displayed a sharp increase, and showed a slight enhancement when the content of CaTiO3 exceeded 12 wt%. The density experienced a continuous decrease with the addition of CaTiO3. The moisture absorption displayed a steady increase with the increasing CaTiO3 loading amount. The changing of dielectric constant (er) and loss tangent (tanδ) were similar to that of the moisture absorption in a manner. Good dielectric properties with values of er = 11.60, tanδ = 0.002 were obtained in the PTFE matrix with 16 wt% CaTiO3 and 45 wt% TiO2.

Crystal structure and microwave dielectric properties of CaTiO3 modified Mg2Al4Si5O18 cordierite ceramics

In this work, CaTiO3 modified Mg2Al4Si5O18 (MAS) of (1−x)MAS-xCaTiO3 (0 ≤ x ≤ 0.35) cordierite ceramics were fabricated by traditional solid phase sintering method. The densification sintering temperatures of (1−x)MAS-xCaTiO3 ceramics are effectively lowered from 1460 °C to 1250 °C with increasing addition of CaTiO3. X-ray diffraction spectra show that (1−x)MAS-xCaTiO3 ceramics present cordierite phase as 0 < x ≤ 0.05, and the composite phases of cordierite, perovskite-structured CaTiO3 and monoclinic feldspar phase of CaAl2Si2O8 as 0.10 ≤ x ≤ 0.35. Rietveld refinement of XRD data show the six-membered rings of [(Si4Al2)O18] transit from non-symmetry rings to centro-symmetry equilateral rings in (1−x)MAS-xCaTiO3 (0 < x ≤ 0.10). The optimal dielectric properties of Q × f = 55490 GHz (at 15.3 GHz), εr = 7.2 and τf = −28.3 ppm/°C are obtained at x = 0.5, which are better than those of pure MAS cordierite ceramics.

Study of the performance of dielectric resonator antennas based on the matrix composite of Al2O3 – CaTiO3

ABSTRACTIn this article is present the structural and dielectric microwave properties of Alumina – CaTiO3 ceramic composite with the addition of CaTiO3 and your performance as a dielectric resonator antenna (DRA). Alumina has a negative temperature variation of resonant frequency coefficient τf, while CaTiO3 has a high positive temperature coefficient. Also influence of calcium titanate on densification and porosity of the composite is presented. The CaTiO3 was added (2.5% to 10% wt. amount) in order to analyze changes in the dielectric properties. Samples were characterized by X‐ray diffraction. Dielectric properties were investigated by Hakki‐Coleman methods and the experimental characteristics parameters like return loss, bandwidth, and input impedance are presented and compared with numerical simulations. The results obtained shows the formation of secondary phases (Hibonite and TiO2), with the dielectric permittivity and dielectric loss increasing and decreasing with calcium titanate concentration, respectively. The application of DRA was verified and all samples tested presented return loss below −10 dB in the resonant frequency. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:963–969, 2015

Effects of CaTiO3 addition on microstructures and electrical properties of Na0.52K0.48NbO3 lead-free piezoelectric ceramics

In this article, various amounts of CaTiO3 (CT) were added into (Na0.52K0.48)NbO3 (NKN) ceramics using conventional oxide-mixing method for improving NKN's properties. The experimental results show that the (1−x)(Na0.52K0.48)NbO3–xCaTiO3 (x=0∼0.07) solid solution system can be successfully synthesized. Addition of CaTiO3 not only effectively prevents materials from deliquescence, but also improves the density and the electrical properties of the ceramics. The dielectric constant–temperature (εr−T) curves exhibit that the temperatures of the Curie point (Tc) and the phase transition from tetragonal to orthorhombic (TO−T) are decreasing monotonously as the amount of CT addition is increased. A morphotropic phase boundary (MPB) can be found in the (1−x)NKN−xCT solid solution system as the doping amount of x=0.03, and the 0.97NKN–0.03CT ceramics, with a high bulk density, 98% theoretical density, and an appropriate grain size of about 1∼2μm, present a superior domain switching ability and the optimum properties: d33=117pC/N, kp=0.39, Pr=21μC/cm2, and Tc=333°C.

Electrical and microstructural properties of CaTiO 3 -doped K 1/2 Na 1/2 NbO 3 -lead free ceramics

Microstructure, electrical properties and dielectric behaviour of K1/2Na1/2NbO3 (KNN) and CaTiO3-modified K1/2Na1/2NbO3 (CTO-KNN) systems, were investigated. Discs doped with 0 to 0·55% mol of CaTiO3 (CTO) were sintered at 1125°C for 2 h. Although minority phases were found in doped samples, CaTiO3 was not detected. It was also observed that CTO changed the microstructure and grain size of KNN drastically. Also, the Curie temperature and permittivity values decreased. Addition of CTO between 0·15 and 0·45 mol% decreases the density and dielectric values. Samples prepared with higher content of CTO than 0·45 mol% showed better electrical properties.