Calcium titanate corrosion inhibitor enabling carbon as inert anode for oxygen evolution in molten chlorides

The corrosion inhibition efficacy of titanate(CaTiO_(3))for carbon anodes in molten salts was investigated through various analytical techniques,including linear sweep voltammetry,X-ray diffraction,scanning electron microscopy,and energy dispersion spectroscopy.The results demonstrate that the addition of CaTiO_(3)corrosion inhibitor efficiently passivates the carbon anode and leads to the formation of a dense CaTiO_(3)layer during the electrolysis process in molten CaCl_(2)-CaO.Subsequently,the passivated carbon anode effectively undergoes the oxygen evolution reaction,with an optimal current density for passivation identified at 400 m A/cm~2.Comprehensive investigations,including CaTiO_(3)solubility tests in molten CaCl_(2)-CaO and numerical modeling of the stability of complex ionic structures,provide compelling evidence supporting“complexation-precipitation”passivation mechanism.This mechanism involves the initial formation of a complex containing TiO_(2)·nCaO by CaTiO_(3)and CaO,which subsequently decomposes to yield CaTiO_(3),firmly coating the surface of the carbon anode.In practical applications,the integration of CaTiO_(3)corrosion inhibitor with the carbon anode leads to the successful preparation of the FeCoNiCrMn high-entropy alloy without carbon contamination in the molten CaCl_(2)-Ca O.

Formation of calcium titanate in the carbothermic reduction of vanadium titanomagnetite concentrate by adding CaCO3

The formation of calcium titanate in the carbothermic reduction of vanadium titanomagnetite concentrate(VTC)by adding CaCO3 was investigated.Thermodynamic analysis was employed to show the feasibility of calcium titanate formation by the reaction of ilmenite and Ca CO3 in a reductive atmosphere,where ilmenite is more easily reduced by CO or carbon in the presence of CaCO3.The effects of CaCO3 dosage and reduction temperature on the phase transformation and metallization degree were also investigated in an actual roasting test.Appropriate increase of CaCO3 dosages and reduction temperatures were found to be conducive to the formation of calcium titanate,and the optimum conditions were a CaCO3 dosage of 18 wt%and a reduction temperature of 1400°C.Additionally,scanning electron microscopy–energy dispersive spectrometry(SEM–EDS)analysis shows that calcium titanate produced via the carbothermic reduction of VTC by CaCO3 addition was of higher purity with particle size approximately 50μm.Hence,the separation of calcium titanate and metallic iron will be the focus in the future study.

Enhanced Biocompatibility and Osseointegration of Calcium Titanate Coating on Titanium Screws in Rabbit Femur

This study aimed to examine the biocompatibility of calcium titanate(CaTiO3) coating prepared by a simplified technique in an attempt to assess the potential of CaTiO3coating as an alternative to current implant coating materials. CaTiO3-coated titanium screws were implanted with hydroxyapatite(HA)-coated or uncoated titanium screws into medial and lateral femoral condyles of 48 New Zealand white rabbits. Imaging, histomorphometric and biomechanical analyses were employed to evaluate the osseointegration and biocompatibility 12 weeks after the implantation. Histology and scanning electron microscopy revealed that bone tissues surrounding the screws coated with CaTiO3were fully regenerated and they were also well integrated with the screws. An interfacial fibrous membrane layer, which was found in the HA coating group, was not noticeable between the bone tissues and CaTiO3-coated screws. X-ray imaging analysis showed in the CaTiO3coating group, there was a dense and tight binding between implants and the bone tissues; no radiation translucent zone was found surrounding the implants as well as no detachment of the coating and femoral condyle fracture. In contrast, uncoated screws exhibited a fibrous membrane layer, as evidenced by the detection of a radiation translucent zone between the implants and the bone tissues. Additionally, biomechanical testing revealed that the binding strength of CaTiO3coating with bone tissues was significantly higher than that of uncoated titanium screws, and was comparable to that of HA coating. The study demonstrated that CaTiO3coating in situ to titanium screws possesses great biocompatibility and osseointegration comparable to HA coating.

Diffusion coefficient of Ti^4+ in calcium ferrite/calcium titanate diffusion couple

This study investigated the interdiffusion of calcium ferrite/calcium titanate system in the time range of 0-120 min by the diffusion couple method in a CO/N2 reducing atmosphere at 700℃.The results show that after the diffusion reaction occurred,no longitudinal agglomerations were present on the substrate surface on the calcium titanate side.When the diffusion time was increased to 105 min,a net vacancy flow from calcium titanate to calcium ferrite might have occurred,causing the surface of the calcium ferrite substrate to collapse.The thickness of the diffusion layer of the calcium ferrite/calcium titanate system was about 17-48μm,which conforms to the parabolic law of diffusion.The diffusion coefficient and the Ti^4+concentration in the calcium ferrite/calcium titanate system are related.This shows an increase in the diffusion coefficient with the increase of Ti^4+concentration,and the diffusion coefficient value was in the range of 10^−12-10^−11 cm^2·s^−1.

Improve titanate reduction by electro-deoxidation of Ca_(3)Ti_(2)O_(7) precursor in molten CaCl_(2)

The low O^(2-)diffusion rate in the electro-deoxidation of titanium containing compounds by either the OS process or the FFC process leads to a low reaction speed and a low current efficiency.In this study,Ca_(3)Ti_(2)O_(7) was used as a precursor to improve the reduction speed of titanium.Because of the greater number of"diffusion channels"created in cathode as Ca^(2+) liberates from Ca_(3)Ti_(2)O_(7) precursor in the electrodeoxidation process,the O^(2-)diffusion rate was improved significantly by using Ca_(3)Ti_(2)O_(7) instead of CaTiO3 as precursor.Parallel constant voltage electrolysis(3.2 V)confirms that Ca_(3)Ti_(2)O_(7) and CaTiO3 are reduced simultaneously because of their similar crystal structures.However,the reduction area of Ca_(3)Ti_(2)O_(7) spreads much faster than that of CaTiO3,indicating a difference in the O^(2-) diffusion rate.Constant voltage cyclic voltammetry(CV)and theoretical analysis of the crystal structure were also conducted to compare the differences between Ca_(3)Ti_(2)O_(7) and CaTiO3.The results indicate that using a precursor with a greater number of soluble cations,titanium reduction speed can be greatly improved in the electro-deoxidation process.Finally,a new electrolysis method for converting and recycling excess CaO from the Ca_(3)Ti_(2)O_(7) precursor was proposed.

Composite materials ferropiezoelectric ceramics-polymer for hydroacoustic receivers

The purpose of this work is to study the processes of interfacial interactions,their influence on the piezoelectric properties in highly elastic composite structures,to establish the patterns that determine the volume-sensitive piezoelectric characteristics of composites and to create effective piezoelectric materials for hydroacoustic receiving devices.In the process of this work,the development of a method for obtaining anisotropic ferropiezoelectric ceramics,the development of methods for the preparation of perfect ceramic powders and composite materials based on thermoplastic fluoropolymers and the study of composite materials based on lead-calcium titanate were carried out.As a result of the study,the dependences of the hydrostatic parameters of the composites on the degree of filling,particle size distribution,piezoelectric anisotropy of the active phase and the elastic properties of the polymer matrix were established.Composite materials were based on ceramics of the PT-CT system and thermoplastic fluoropolymers F-2ME,F-62,F-2N with a degree of filling with a ceramic phase from 30 to 60%vol.The dependences of the hydrostatic piezoelectric moduli gh and dh,and the quality factor gh·dh on the degree of filling of the composite for polymers F-62 and F-2ME with different average sizes of ceramic particles are plotted.It has been established that the maximum values gh=119.1·10^(−3)V·m/N and the quality factor g_(h)·d_(h)=6074·10^(−15)m^(2)/N are achieved for a polymer with a higher elastic compliance(F-62)at a degree of filling of 60%vol.and the use of granular filler.

Manufacturing and characterizing of CCTO/SEBS dielectric elastomer as capacitive strain sensors

Calcium copper titanate(CCTO)/polystyrenepolyethylene-polybutylene-poly styrene(SEBS)dielectric elastomers were prepared via blending method.A capacitive strain sensor using CCTO/SEBS as dielectric layer and polyaniline-dodecylbenzensulfonic acid(PANI-DB S A)/SEBS as electrodes was designed and manufactured by thermoforming process.X-ray diffractometer(XRD),scanning electron microscopy(SEM)and Raman spectra analyses were carried out;no impurities were found in the composite and CCTO particles were well dispersed.The dielectric tests showed that the samples filled with 20 wt%CCTO have their permittivity improved by 70%.The capacitive strain sensors have a stabilized capacitance variety range at different strain ranges or stretch speeds,and could remain synchronized after 500-time-stretching,showing high reproducibility.

Investigations on luminescence of rare earths doped CaTiO_3:Pr^(3+) phosphor

Calcium titanate doped with praseodymium was prepared through solid state reaction and it exhibited intense red emission at 612 nm. Phosphors were characterized for photoluminescence, thermo-luminescence and afterglow emissions. Study of effects of rare earths on photoluminescence as well as afterglow intensity was reported. Presence of gadolinium enhanced luminescence. Presence of some monovalent ions enhanced both afterglow and photoluminescence emission. Thermo-luminescence glow curves were analyzed and ...

Enhanced photoluminescence of CaTiO_3:Eu^(3+) red phosphors prepared by H_3BO_3 assisted solid state synthesis

CaTiO3：Eu3＋ red phosphors were prepared using H3BO3 assisted solid state synthesis. The structure and morphology of the obtained sample were observed by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. And the luminescence property was measured using photoluminescence excitation （PLE） and photoluminescence （PL） spectra, respectively. In the excitation spectra, main excitation peaks of the prepared samples were centered at 397 and 465 nm, revealing that these phosphors could be excited by commercial GaN- and InGaN-typed light emitting diodes （LEDs）. Dominant emission peaks of the phosphors were located at 616 nm, owing to the transition of 5D0→7F2 of Eu3＋. In the optimum condition, CaTiO3：3%Eu3＋ phosphor was obtained at a sintering temperature of 1200 °C in air with a content of 20 mol.% H3BO3 addition. When excited by 397 nm irradiation, the PL intensity of as-prepared red phosphor was 2.2 times higher than that of samples obtained by traditional solid state synthesis, while the PL intensity was 3 times higher than that excited by 465 nm irradiation. The added H3BO3 improved the crystallinity, and increased the color purity, implying the potential to be a promising red phosphor in white light emitting diodes （WLEDs）.

Synthesis and photoluminescence of Ca1-xTiO3 ：xEu^3＋ nanoparticles

Ca1-xTiO3 ：xEu^3＋ nanoparticles （NPs） with the size ranging from 27 nm to 135 nm were prepared by means of a chemical co-precipitation method. The structural and optical properties of the NPs were investigated, and the influence of Eu doping content and sintering temperature on the photoluminescence of the Ca1-xTiO3 ：xEu^3＋ NPs were examined. An obvious red emission band centered at 615 nm were observed under the excitation with 395 nm for the Ca1-xTiO3 ：xEu^3＋ NPs. X-ray photoelectron spectroscopy analyses suggest that Eu^3＋ is incorporated into not only the Ca-site, but also Ti-site of CaTiO3 crystal lattice. Our study shows the promise of the Ca1-xTiO3 ：xEu^3＋ NPs as a red nanophosphor.

Influence of CeO_2 doping amount on property of BCTZ lead-free piezoelectric ceramics sintered at low temperature

Ba0.85Ca0.15Ti0.9Zr0.1O3 （BCTZ） lead-free piezoelectric ceramics co-doped with CeO2 （x=0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%） and Li2CO3 （0.6 wt.%） were prepared by conventional solid-state reaction method. Influence of CeO2 doping amount on the piezoelectric properties, dielectric properties, phase composition and microstructure of prepared BCTZ lead-free piezoelectric ceramics doped with Li2CO3 were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM） and other analytical methods. The results showed that the sintered temperature of BCTZ lead-free piezoelectric ceramics doped with CeO2 decreased greatly when Li2CO3 doping amount was 0.6 wt.%;a pure perovskite structure of BCTZ lead-free piezoelectric ceramics co-doped with Li2CO3 and CeO2 and sintered at 1050 ℃ could also be obtained. The piezoelectric constant （d33）, the relative permit-tivity （εr） and the planar electromechanical coupling factor （kp） of BCTZ ceramics doped with Li2CO3 increased firstly and then de-creased, the dielectric loss （tanδ） decreased firstly and then increased and decreased at last when CeO2 doping amount increased. The influence of CeO2 doping on the properties of BCTZ lead-free piezoelectric ceramics doped with Li2CO3 were caused by“soft effect”and “hard effect”piezoelectric additive and causing lattice distortion. When CeO2 doping amount （x） was 0.2 wt.%, the BCTZ ceramics doped with Li2CO3 （0.6 wt.%） and sintered at 1050 ℃ possessed the best piezoelectric property and dielectric property with d33 of 436 pC/N, kp of 48.3%,εr of 3650, tanδof 1.5%.

Fabric-substrated capacitive biopotential sensors enhanced by dielectric nanoparticles

Wearable biopotential sensing devices are essential to long-term and real-time monitoring of human health.Non-contact,capacitive sensing electrodes prevent potential skin iritations,and are thus beneficial for long-term monitoring.Existing capacitive electrodes are either connected to a separate control circuit via external wires or have limited sensing capacitances,which leads to low signal qualities.This study demonstrates a stretchable capacitive sensing device with integrated electrodes and control electronics,with enhanced signal qualities.The electrodes and the control electronics are fabricated on a common fabric substrate for breathability and strain-limiting protection.The stretchable electrodes are based on an island-bridge design with a stretchability as high as-100%,and an area ratio as high as-80%.By using a dielectric calcium copper titanate(CCTO)composite as the adhesive layer,the electrode capacitance can be increased,yielding an enhanced signal-to-noise ratio(SNR)in the acquired biopotentials.This device offers a convenient and comfortable approach for long-term non-contact monitoring of biopotential signals.