CaTiO3 Phase Research Articles

High dielectric breakdown strength of antipolar CaTiGeO5 ceramics sintered at optimized temperature

Titanite CaTiSiO5 (CTS) is considered to be a promising dielectric material for preparing high-voltage multilayer ceramic capacitors because it exhibits a positive bias dependence of the dielectric permittivity due to its antipolar crystal structure. In this study, we investigated the dielectric response and breakdown strength of CaTiGeO5 (CTG), a structural analog of CTS, inspired by its higher low-field dielectric permittivity. Particular attention was paid to the sintering temperature to reveal the effect of the microstructure and loss of volatile Ge on the electrical properties of CTG. Dense CTG ceramics with relative densities above 97 % and grain sizes between 1.3 and 3.4 μm were obtained through a conventional solid-state reaction route at sintering temperatures between 1150 and 1250 °C. A secondary phase of CaTiO3 was formed in the ceramics sintered at 1200 and 1250 °C due to Ge loss, but this phase was easily removed by surface polishing alone. The sintering temperature largely affected the dielectric breakdown strength through microstructural development, resulting in the highest breakdown strength of 1190 kV cm−1 for a sample sintered at 1200 °C, while it did not change the low-field dielectric properties of the samples. Furthermore, the sample retained high breakdown strength of >900 kV cm−1 at elevated temperatures up to 150 °C and exhibited a nonlinear polarization response, resulting in the positive electric field dependence of the dielectric permittivity.

Structure, dielectric, and energy storage properties of perovskite CaTiO3 ceramic synthesized using the natural calcium from Pensi shell (Corbicula moltkiana) waste

Recently, dielectric capacitors have attracted immense interest as energy storage materials. In this work, we prepare the dielectric material CaTiO3 by the molten-salt method, utilizing Pensi shell waste as a natural calcium source, aligning with principles of green chemistry. Pensi shell contains 53.1 % calcium oxide, as revealed by TGA analysis, suggesting its potential use as a natural precursor in CaTiO3 synthesis. The phase formation, structure, and electrical properties of the resulting CaTiO3 phase are investigated. XRD data revealed the formation of single-phase CaTiO3 and a distortion of the TiO6 octahedra, accompanied by displacement of the A-site cations resulting in an orthorhombic Pbnm structure. CaTiO3 exhibits good linear dielectric characteristics with an energy storage efficiency of 84.8 %.

A novel Magnéli-phase Ti9O17-containing anode by controlled reductive decomposition of calcium copper titanate perovskite under hydrogen atmosphere for paracetamol degradation

CaCu3Ti4O12 (CCTO) materials show high efficacy in water treatment due to their perovskite structure and exceptional chemical stability. Their combination with electro-oxidation and sulfate-based advanced processes represents a promising approach for water treatment applications. CCTO can be modified through various processes to enhance its activity in water treatment. In this study, CCTO was synthesized using ball milling, and the effects of different sintering treatments were evaluated. The treatment with different atmospheres led to CCTO decomposition. Upon sintering under nitrogen, CCTO broke down into the CaTiO3, Cu2O, and rutile TiO2 phases. Conversely, sintering under hydrogen (CCTOH2) led to the reduction of Cu and TiO2 and the creation of Cu and Magnéli phase Ti9O17. CCTOH2 exhibited the highest electrochemical properties due to the presence of Magnéli phases that enhanced electron transfer and conductivity. The decomposition treatment effect on the water treatment performance was evaluated using an electro-oxidation/peroxymonosulfate system. The results showed that when CCTOH2 membranes were used as anodes, paracetamol was completely removed within 10 min. Toxicity was evaluated using Vibrio fischeri. After 1 h, bacterial luminescence inhibition rate dropped to 0 % (from ∼96 % at 2 min), demonstrating paracetamol degradation into non-toxic compounds. Furthermore, CCTOH2 efficacy was tested in the presence of dissolved and colloidal matter from a laboratory-scale secondary effluent. The results demonstrated consistent efficiency in paracetamol degradation in real water and the additional removal of fluorophores. After demonstrating the efficacy of our CCTOH2 membrane, it is now important to test it in large scale experiments.

LVOF sprayed Ti-HAp composite coatings for internal fixation devices in orthopaedic applications

Pure hydroxyapatite, pure titanium, Ti60-HAp (60%Ti), and Ti40-HAp (40%Ti) composite coatings were deposited on 254 SMO steel by Low-Velocity Oxy-fuel (LVOF) spraying. Among the various LVOF sprayed coatings, the Ti40-HAp coating has the highest microhardness and adhesion strength values attributed to its low porosity and low coefficient of thermal expansion. The potentiodynamic polarisation and electrochemical impedance spectroscopy tests also indicated a lower corrosion rate for Ti40-HAp coating in simulated body fluid (SBF). The bacterial adhesion has shown a direct relationship with the surface roughness of the coatings. The bioactivity of the Ti-HAp composite coating was established through an in-vitro bioactivity test. The bioactivity decreased with increasing Ti content in the coating. The formation of rutile TiO2 and CaTiO3 phases significantly enhanced the microhardness, adhesion strength and corrosion resistance.

Dominant role of ceramic connectivity in microwave dielectric properties of porous ceramics

The connectivity of constituting phases plays an important role in the physical properties of composites and porous materials, while it is still overlooked in many cases. In the present work, CaTiO3 is used as the model material to clarify the effect of ceramic connectivity on the microwave dielectric properties of porous ceramics. CaTiO3-A and CaTiO3-B porous ceramics are prepared by partial sintering at 700–1200 °C and sintering at the optimum temperature of 1350 °C with the aid of porogen, respectively. With increasing the sintering temperature from 700 to 1000 °C, the relative density of CaTiO3-A ceramics maintains around 58%, while their εr, Qf, and τf increase dramatically (20.4–48.2, 968–4,237 GHz, and 443.9–724.2 ppm/ °C). The three parameters are even higher in CaTiO3-B ceramic with a similar relative density of 54.1% (69.1, 5,658 GHz, and 782.9 ppm/ °C). The huge variation in microwave dielectric properties is attributed to the significantly improved ceramic connectivity with sintering temperature observed from microstructure analysis. Finite element analysis further reveals that the ceramic connectivity plays the dominant role in the microwave dielectric properties by deciding the electric field distribution in CaTiO3 phase and pores and hence their contribution to dielectric response. The exponent α in exponential dielectric mixing rule is employed to describe the ceramic connectivity, and the trinary relationship among the microwave dielectric properties, constitution, and microstructure of porous ceramics is well constructed. This relationship can be extended to ceramic-polymer and ceramic-ceramic composites, which brings new perspectives for designing such microwave dielectric materials.

Fabrication of CaAl12O19–CaTiO3 composites and their potential usage for TiAl alloy smelting

AbstractCaAl12O19–CaTiO3 (CA6–CT) materials are fabricated using a solid sintering method to investigate the effects of TiO2 content on the phase composition, properties, and microstructure of the materials. With increasing TiO2 content, the preferential replacement of Al3+ by Ti4+ in the CA6 crystal increases the concentration of vacancy defects, thereby promoting ion diffusion and mass transfer, which improves the sintering reaction activity. However, as more TiO2 is added, the CaTiO3 phase formed increases the thermal conductivity and mean expansion coefficient of the material at high temperatures, which degrades its thermal shock stability. The CA6–CT refractory showed good corrosion resistance to the Ti6Al4V melt. Except for a slight penetration of iron element, no obvious corrosion occurred at the reaction interface.

Significantly improved giant dielectric properties and enhanced nonlinear coefficient of Ni2+ doped CaCu3Ti4O12/CaTiO3 composites

CaCu3-xNixTi4O12/CaTiO3 ceramic composites were fabricated using initial Ca2Cu2-xNixTi4O12 compositions (x = 0, 0.05, 0.10, and 0.20) to improve the dielectric properties (DPs) of the CaCu3Ti4O12 ceramics. CaCu3Ti4O12 and CaTiO3 phases were confirmed. Microstructural analysis and Rietveld refinement showed that the Ni2+ dopant might substitute the Cu2+ sites of the CaCu3Ti4O12 structure. The average grain sizes of CaCu3Ti4O12 (4.1–5.6 μm) and CaTiO3 (1.2–1.4 μm) changed slightly with the Ni2+ doping concentration. The best DPs were obtained for the CaCu3-xNixTi4O12/CaTiO3 with x = 0.2. The loss tangent was significantly reduced by an order of magnitude compared to that of the undoped composite, from tanδ∼0.161 to ∼0.016 at 1 kHz, while the dielectric permittivity slightly decreased from ε′∼5.7 × 103 to ∼4.0 × 103. Furthermore, the temperature dependence of ε′ could be improved by doping with Ni2+. The improved DPs were caused by the enhanced electrical responses of the internal interfaces, which resulted in enhanced non–Ohmic properties. The largest nonlinear coefficient (α∼7.6) was obtained for the CaCu3-xNixTi4O12/CaTiO3 with x = 0.05. Impedance spectroscopy showed that the CaCu3-xNixTi4O12/CaTiO3 composites consisted of semiconducting and insulating components. The DPs of CaCu3-xNixTi4O12/CaTiO3 were explained based on the space−charge polarization at the active−interfaces.

Properties of various CaO-Al2O3-TiO2 refractories and their reaction behaviours in contact with Ti6Al4V melts

Vacuum induction melting technology is an important method for producing high-quality titanium alloy. The key challenge lies in the development of refractories with excellent chemical stability for titanium alloy corrosion. In this work, CaO-Al2O3-TiO2 refractories are proposed as the potential materials for Ti6Al4V alloy smelting. Four CaO-Al2O3-TiO2 refractories with different TiO2 contents were prepared and their reaction behaviours in contact with titanium aluminum melts were investigated in detail. When the refractory has a suitable content of CaTiO3 phase, it promotes the diffusion and mass transfer rate of ions and improves the sintering reaction activity, leading to good high temperature mechanical properties and corrosion resistance to titanium aluminum alloy. However, when the TiO2 component is excessive, CA6 has been completely wrapped by CaTiO3, and some CA6 grows abnormally, resulting in a decrease in high temperature mechanical properties of the refractory. Moreover, during the smelting of Ti6Al4V alloy, Al component reacts with CaTiO3 to produce metallic Ti and calcium aluminate phase with low melting point, resulting in degradation of refractory.

The Enhanced Thermal Stability of (Mg0.95Ni0.05)2TiO4 Dielectric Ceramics Modified by a Multi-Phase Method.

The thermal stability of (Mg0.95Ni0.05)2TiO4 dielectric ceramics has been improved by mixing with CaTiO3 phases owing to higher positive temperature coefficients. The pure (Mg0.95Ni0.05)2TiO4 and the mixture phase systems of CaTiO3-modified (Mg0.95Ni0.05)2TiO4 were verified by XRD diffraction patterns to ensure the crystallite of different phases. The microstructures of the CaTiO3-modified (Mg0.95Ni0.05)2TiO4 were observed by SEM and EDS to investigate the relation between element ratios and grains. As a result, it can be seen that the thermal stability of the CaTiO3-modified (Mg0.95Ni0.05)2TiO4 can be effectively enhanced, compared with the pure (Mg0.95Ni0.05)2TiO4. Moreover, the radio frequency dielectric performances of CaTiO3-modified (Mg0.95Ni0.05)2TiO4 dielectric ceramics are strongly dependent upon the density and the morphology of the specimens. The champion sample with the ratio of (Mg0.95Ni0.05)2TiO4 and CaTiO3 of 0.92:0.08 showed an εr value of 19.2, an Qf value of 108,200 GHz, and a τf value of -4.8 ppm/°C, which may encourage (Mg0.95Ni0.05)2TiO4 ceramics to broaden the range of novel applications and match the requirements of 5G or next-generation communication systems.

Laser cladding of HA-TiO2 composite coating on Mg-alloy: microstructural characterisation and wettability analysis

ABSTRACT In the present work, hydroxyapatite (HA)-50 wt.% TiO2 composite coating has been developed on Mg-alloy by laser cladding process using 400 W continuous wave fibre laser. A detailed microstructural characterisation has been done by using optical profilometry, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction techniques. The wettability analysis has been done by the sessile method using hank’s solution. The average roughness is 0.5 μm for the Mg-1% Ca alloy and 1.45 μm for laser-cladded surface. The microstructure analysis shows uniform deposition with the presence of porosities, particles and few cracks on the top surface of laser-cladded surface. The composition analysis shows the uniform and homogeneous distribution of Ca, Ti, P, and O on the laser-cladded surface. The phase analysis shows the presence α, β phase in Mg-1% Ca alloy and the presence of Ca2P2O7, Ca3(PO4)2, CaTiO3 and TiO2 (rutile) phases in the laser-cladded surface. There is an improvement in wettability of the laser-cladded surface as compared to as-received Mg alloy.

Process Development of Zirconolite Ceramics for Pu Disposition: Use of a CuO Sintering Aid

Zirconolite-structured ceramics are candidate wasteform materials for the immobilisation of separated Pu. Due to the refractory properties of zirconolite and other titanates, removing residual porosity remains challenging in the final wasteform product when utilising a conventional solid state sintering route. Herein, we demonstrate that the addition of CuO as a sintering aid increases densification and promotes grain growth. Moreover, zirconolite phase formation was enhanced at lower process temperatures than typically required (≥1350 °C). CuO addition allowed an equivalent density to be reached using process temperatures of 250 °C lower than the undoped composition. At 150 °C lower than the undoped zirconolite, the addition of CuO resulted in a favourable microstructure and phase assemblage, as confirmed via X-ray diffraction and scanning electron microscopy. Secondary phases of CaTiO3 and Ca0.25Cu0.75TiO3 were observed at some processing temperatures, which may prove deleterious to wasteform performance. The use of a CuO sintering aid provides an avenue for the further development of the thermal processing of ceramic wasteform materials.

Theoretical Examination of the Radiation Protecting Properties of CaTiO3 Material Sintered at Different Temperatures

This research is devoted to studying the radiation-protecting characteristics of calcium titanate (CaTiO3) perovskite-based ceramic material. The ceramics were made by the solid-state reaction method (SSRM) and treated at temperatures of 1300 °C, 1200 °C, and 1100 °C. The structural characteristics of the ceramics were analyzed by XRD and FT-IR. The results indicated a CaTiO3 phase formation with an orthorhombic structure. The size of the crystallites was in the range of 27–36 nm and was found to increase as the temperatures increased. The relative density showed an increase from 93% to 96% as the temperatures varied from 1100 °C to 1300 °C. The impact of temperature on the radiation-protecting characteristics of the CaTiO3 ceramic was assessed using the Monte Carlo simulation (MCS). There was a slight decrease in the γ-photons average track length with a raising of the temperature. At a γ-photon energy of 0.662 MeV, the γ-photons’ average track lengths diminished from 3.52 cm to 3.38 cm by raising the temperature from 1100 °C to 1300 °C. The illustrated decrease in the γ-photons average track length affected the linear attenuation coefficient (µ) where the µ increased from 0.28 to 0.30 cm−1 with a rising temperature from 1100 °C to 1300 °C.

Realizing ultrahigh breakdown strength and ultrafast discharge speed in novel barium titanate-based ceramics through multicomponent compounding strategy

Lead-free dielectric ceramics have been an important segment in the energy storage field. In this work, a synergistic optimization strategy of multicomponent compounding involving 0.9[0.88Ba1-xCaxTiO3-0.12Bi(Mg2/3(Nb0.85Ta0.15)1/3)O3]− 0.1Bi0.5Na0.5TiO3 (B1-xCxT-BMNT-BNT) ceramics were proposed. With the increase of Ca2+ content (x), the content of the CaTiO3 phase increases, which obviously enhances the breakdown strength (BDS) and energy storage properties. The optimal energy storage performances were obtained in the B0.6C0.4T-BMNT-BNT ceramic, showing a large recoverable energy density (Wrec) of 3.59 J/cm3 and ultrahigh efficiency (η) of 90.86% at 430 kV/cm. Meanwhile, the B0.6C0.4T-BMNT-BNT material also exhibits good temperature stability (20–180°C), frequency stability (1–500 Hz) and fatigue resistant (1–105 cycles). In addition, the B0.6C0.4T-BMNT-BNT ceramic also possesses ultrafast discharge time (t0.9 = 38.6 ns) in the charge and discharge test. The above merits make the B0.6C0.4T-BMNT-BNT ceramic a promising candidate for wide-temperature dielectric capacitors in pulse power applications.

Significantly enhanced hybrid improper ferroelectricity of Ca3Ti2O7 ceramics by the oxygen vacancy engineering

Ca3Ti2O7 materials with hybrid improper ferroelectricity call tremendous interest due to their great potential in designing novel room-temperature single-phase multiferroics with a strong magnetoelectric coupling effect. However, achieving Ca3Ti2O7-based ceramics with superior room-temperature ferroelectricity remains a crucial challenge. Herein, Ca3Ti2O7 ceramics were prepared by a tartaric acid sol–gel method and sintered in air and oxygen atmospheres, respectively. It was found that the long-time high-temperature sintering in air could lead to the formation of CaTiO3/Ca3Ti2O7/CaTiO3 sandwich structure, and oxygen-enriched sintering could effectively avoid the formation of CaTiO3 phase on the surface. The superior hybrid improper ferroelectricity is attained in Ca3Ti2O7 ceramics sintered in oxygen atmosphere with a higher remnant polarization (3.63 μC/cm2) and lower coercive electric field (72.6 kV/cm) obtained by positive-up and negative-down method, which is better than the ceramic sample sintered in air. The significantly better ferroelectricity is benefited from the synergistic effects of its larger distortion of oxygen octahedron, larger grain size, and lower oxygen vacancy concentration. Due to its low leakage current density, Ca3Ti2O7 ceramics sintered in oxygen atmosphere exhibit the remanent polarization as high as 7.40 μC/cm2 under the conditions of 1 Hz and 200 kV/cm obtained by dynamic hysteresis measurement mode. Furthermore, there are obvious stripe ferroelectric domains, which provide direct evidence for the excellent hybrid improper ferroelectricity of Ca3Ti2O7 ceramics. These findings demonstrate that the oxygen vacancy engineering is an effective strategy to improve hybrid improper ferroelectricity of Ca3Ti2O7 materials.

Enhanced performance of free CaO impurity containing magnesia with Al2O3–TiO2 composite powder

Free CaO impurity containing magnesia has intrinsic shortcomings of poor resistance to hydration, thermal shock and slag penetration. Here, a novel approach, the introduction of Al2O3–TiO2 composite powder, is proposed to enhance the performances of such magnesia in present work. The results showed that with increasing the composite powder, CaTiO3 and Mg1+xAl2(1-x)TixO4 phases were sequentially formed at MgO grain boundaries, which affected the microstructure and properties of the specimens. The addition of composite powder enhanced the MgO grains growth and conversion of free CaO to CaTiO3, and therefore weight gain rate of the specimens after hydration test reduced from 0.212% to 0.097% with increasing Al2O3–TiO2 from 0 wt% to 7 wt%. The formed CaTiO3 and Mg1+xAl2(1-x)TixO4 phases reduced the thermal expansion coefficient and induced the crack deflection, and therefore thermal shock resistance of the specimens improved obviously with the composite powder content. Besides, slag penetration resistance of the specimens was enhanced significantly as 3 wt% composite powder was added, attributing to the increase of MgO grain size and contact angle and formation of high stable intergranular CaTiO3 phase. However, further increasing Al2O3–TiO2 lowered the slag penetration resistance due to the reduction of contact angle and formation of low stable Mg1+xAl2(1-x)TixO4 phase at MgO grain boundaries.

Chrome-free qandilite (Mg2TiO4) refractory aggregates: Role of titania source and evaluation of thermal expansion coefficient

As used chrome-based refractories may contain toxic Cr6+, the chrome-free Mg2TiO4 phase is being considered which is known to improve hot strength and resistance to thermal shock and slag corrosion. As in situ Mg2TiO4 formation generates porosity, preformed aggregates are desirable. Dilatometric studies revealed that when dead burned magnesia is combined with industrial anatase instead of rutile, it expanded less (1 % versus 7.2 %) and the reaction occurred earlier (965 ℃ compared to 1120 ℃). After sintering at 1,600 ℃, rutile produced an aggregate with 3.8 % open porosity, whereas anatase led to 0 % porosity and a bulk density of 3.24 g/cm3 with a thermal expansion coefficient (70–1,600 ℃) of 13.5 × 10−6 K−1. Moreover, replacing rutile by anatase eliminates the undesirable MgTiO3 phase. The anatase-based aggregate consisted of a Mg2TiO4 matrix with residual unreacted MgO and an intergranular, refractory CaTiO3 phase. The rutile-based aggregate was deemed unsuitable due to a low-melting microstructure of forsterite contiguous with CaTiO3.

Effect of Crystal Structure and Phase on the Dielectric, Ferroelectric, and Piezoelectric Properties of Ca2+- and Zr4+-Substituted Barium Titanate

Barium titanate (BaTiO3) and its associate ternary metal oxide systems constitute versatile materials with immense potential for various technological applications in electronics and optoelectronics. Herein, we report on the synthesis and property optimization of lead-free ceramic samples, namely BaTiO3 (BT), BaZr0.2Ti0.8O3 (BZT), Ba0.7Ca0.3TiO3 (BCT), and BaZr0.2Ti0.8O3–0.5 Ba0.7Ca0.3TiO3 (BZT–BCT) composites. All of these materials were synthesized by the standard solid-state chemical reaction method, where tuning the composition and the crystal structure yields materials suitable for multifaceted applications related to capacitors, memory storage, and high-energy switching and transducers. Structural studies carried out using X-ray diffraction and Raman spectroscopy confirm the tetragonal phase for BT, BZT, and BZT–BCT samples, whereas BCT is a biphasic crystal system, which contains a small amount of the CaTiO3 phase. Scanning electron microscopy characterization of the surface morphology indicates the granular-dense microstructures of all of the samples. Energy dispersive spectroscopy confirms the high degree of purity and chemical homogeneity of the synthesized samples in addition to a well-maintained composition. Density measurements using Archimedes principles show that all of the samples have densities above 4.96 g/cm3. All of these materials exhibit typical polarization–electric field (P–E) hysteresis and field-induced strain butterfly (S–E) loops, which confirm their ferroelectric and piezoelectric nature. The frequency response of the dielectric constant shows a maximum dielectric constant of 2441 for pure BT and it decreases for higher frequencies, above 0.1 MHz. The dielectric properties of BT imply significant prospects for its future capacitor applications. Ferroelectric measurements, which are established by measuring the P–E hysteresis loop at 300 K, show that the BCT samples exhibit a 0.50 squareness ratio. The detailed analyses indicate that BCT is a candidate material for permanent memory storage device (FeRAM) applications, whereas BZT is good for switching applications. Furthermore, a moderately higher remnant polarization (Pr = 10.81 μC/cm2) is obtained for BT and a lower coercive field (Ec = 0.78 kV/cm) is obtained for the BZT sample. Also, piezoelectric coefficient and strain measurements show that BT has a piezoelectric coefficient of 183 ± 1 pC/N and a converse piezoelectric coefficient of 365.7 ± 2 pm/V, which are the highest values. The Q-factor for the BZT–BCT composite was observed to be 4.16 × 10–4 (cm2/μC)2, which is maximum, implying that BZT–BCT is suitable for energy conversion transducer applications. In this work, we comprehensively elucidate and discuss the properties and potential applications of BT and its associated ternary metal oxide systems.

Effect of Smelting Time on Vanadium and Titanium Distribution Behavior and Slag Viscosity in HIsmelt

HIsmelt is well suited for smelting vanadium–titanium magnetite due to its flexibility in feedstock selection and tolerance to high viscosity slag, compared with the blast furnace. In this work, the effect of smelting time on the distribution behavior and recovery rates of vanadium and titanium in HIsmelt smelting of vanadium–titanium magnetite was investigated by experiment for the first time. The relationship between slag viscosity and temperature at different smelting times was further revealed by thermodynamic calculations. The experimental results show that extending the smelting time increases the FeO content in the slag, the LV rose from 0.66 to 5.02, the LTi declined from 206.90 to 114.86, the shorter smelting time is favorable for increasing the recovery ratio of vanadium and titanium in metal and slag. In addition, slag viscosity decreases with increasing smelting time. The precipitation of high melting point titania spinel and CaTiO3 phases is responsible for the significant increase in slag viscosity at 1300 °C.

Electrochemical Mechanism of Molten Salt Electrolysis from TiO2 to Titanium.

Electrochemical mechanisms of molten salt electrolysis from TiO2 to titanium were investigated by Potentiostatic electrolysis, cyclic voltammetry, and square wave voltammetry in NaCl-CaCl2 at 800 °C. The composition and morphology of the product obtained at different electrolysis times were characterized by XRD and SEM. CaTiO3 phase was found in the TiO2 electrochemical reduction process. Electrochemical reduction of TiO2 to titanium is a four-step reduction process, which can be summarized as TiO2→Ti4O7→Ti2O3→TiO→Ti. Spontaneous and electrochemical reactions take place simultaneously in the reduction process. The electrochemical reduction of TiO2→Ti4O7→Ti2O3→TiO affected by diffusion was irreversible.

Structural and Optical Properties of Calcium Titanate Prepared from Gypsum

Ceramic materials have been used in various human health-related applications for considerable time. One of the important applications of ceramic materials is in electronics. Our work focuses on calcium titanate (CaTiO3). CaTiO3 is typically created via sintering. Gypsum particles is used to form calcium hydroxide, which is then combined with titanium dioxide to form rutile crystals. Thereafter, calcination is performed at 900°C, 1000°C, and 1100°C for 2 h. X-ray diffraction is employed to track the evolution of the CaTiO3 phase. Scanning electron microscopy is used to characterize the morphologies of the different preparation steps. As the calcination temperature increases from 900°C to 1000°C, the crystallite size of CaTiO3 increases from 35 nm to 45 nm. Furthermore, the energy gaps of the CaTiO3 powders obtained after calcination at 900°C and 1000°C are 5.32 eV and 5.43 eV, respectively, and their particle sizes are 150–200 nm and 200–300 nm, respectively.