TiO2 ZrO2 Research Articles

Silver-doped ZrO2-TiO2 nanocomposite coatings on 316L stainless steel for enhanced corrosion resistance and bio applications

The demand for ceramic based nanocomposite coatings has increased because they play a significant role in orthopedic implants and medical devices. Ceramic nanocomposites are inert and highly biocompatible, which improve corrosion resistance under physiological fluids. The ceramic nanocomposites were deposited (silver-doped ZrO2/TiO2) on SS 316L, and their biocompatibility, strength of adhesiveness, and corrosion resistance properties were studied. A detailed investigation of corrosion resistance, wettability, and biocompatibility concerning microstructures and the inclusion of silver as a dopant was conducted. The deposited films annealed at 600 °C display crystallinity with the coexistence of TiO2 rutile and ZrO2 monoclinic phases. The surface morphology shows the average particle size on thin film is around 40 to 45 nm. The deposited films show a decreased corrosion current density (ICorr) in potentiodynamic polarization curves, confirming the adequate protection against corrosion using simulated body fluid and phosphate buffer saline at 37±1 °C. The surface wettability of coatings is hydrophilic, and it improves in-vitro compatibility. The apatite growth in SBF solution on the implant surface predicts a favorable condition for bone regeneration in the patient's body. The effect of silver dopant on improving apatite growth on implant surface is also discussed. From electrochemical impedance spectroscopy, the diameter of the semicircle in the Nyquist plot shows more than bare metal; the higher the diameter indicates the more resistive behavior of deposited films, which shows the effective corrosion resistance in the electrolytic solution. It is found that the biocompatibility and corrosion resistance are improved compared with bare SS 316L. Hence, ceramic nanocomposite coatings show great potential in the orthopedic implant industry.

Production of Porous ZrO2–TiO2 Ceramic Coatings on the Biomedical Ti-6Al-4V Alloy via AC PEO Treatment and Their Effects on the Corrosion Behavior in 0.9% NaCl

Production of Porous ZrO2–TiO2 Ceramic Coatings on the Biomedical Ti-6Al-4V Alloy via AC PEO Treatment and Their Effects on the Corrosion Behavior in 0.9% NaCl

STUDY OF THERMAL COEFFICIENT OF LINEAR EXPANSION OF BIOCOMPATIBLE GLASS CRYSTALLINE MATERIALS BASED ON THE SYSTEM Li2O–СaO–ZrO2–TiO2–MgO–ZnO–Al2O3–B2O3–P2O5–SiO2

The prospect of using biocompatible scaffolds with bone tissue architecture to replace large areas of bone tissue has been established. The necessity of creating reinforced porous bioactive glass-crystalline materials, which are operated under conditions of variable loads and characterized by high osteoconductive and osteoinductive properties, has been established. The main criteria for the formation of a reinforced hierarchical porous structure of bioactive glass-crystalline materials under the conditions of heat treatment have been determined. The choice of the system is justified Li2O–СaO–ZrO2–TiO2–MgO–ZnO–Al2O3–B2O3–P2O5–SiO2, within which the compositions of the OS series glasses with the content of the main components and modifying additives are selected, wt. %. %: CaF2 0,5–2,5; CeO2 0,01–0,05; SrO 0,01–0,05; Nb2O3 0,01–0,1; SrO 0,01–0,1 and with the ratio Са:P = 1,67 and SiO2:Li2O = 4,0 and glass-crystalline materials were developed, which are characterized by the content of crystalline phases of hydroxyapatite and lithium disilicate for the formation of a bioactive reinforced structure. The influence of the chemical and phase composition of model glasses on the crystallization ability and thermal properties of glass-crystalline materials based on them was analyzed. It was determined that the indicator TСLЕ indicator for experimental glass materials in the temperature range of 25–600 °С is 78–130,2·10-7°С-1 and is recognized by the type and content of crystalline phases and the composition of the glass phase. It was established that the formation of a sytalized interconnected structure with the presence of 50 vol. % hydroxyapatite and 10 об. % lithium with TСLЕ about 100·10-7°С-1, determines the possibility of obtaining high-quality durable and defect-free porous biocompatible materials and coatings on titanium alloys based on calcium-silicophosphate glass-crystalline materials for creating a single endoprosthesis design. The creation of reinforced nanostructured glass-crystalline materials with a hierarchical porous structure, the ability to withstand thermal loads and the formation of a strong connection with titanium alloys will allow solving the urgent problems of replacing significant areas of bone tissue.

Reinforced dielectric properties and energy storage performance of BaO–Na2O–Nb2O5–SiO2–TiO2–ZrO2 dielectric glass ceramics

Glass ceramic capacitors with ultra-fast discharge speed and high energy density play a key role in pulse power systems. However, the low dielectric performance of glass ceramics limits their energy storage density. To reinforce the dielectric properties and energy storage capacity of glass ceramics, the microstructures and contents of the ceramic phases composing BaO–Na2O–Nb2O5–SiO2–TiO2–ZrO2 glass ceramics can be effectively controlled by adjusting different crystallization conditions. At the optimum crystallization temperature of 950 °C, the maximal theoretical energy storage density of BaO–Na2O–Nb2O5–SiO2–TiO2–ZrO2 dielectric glass ceramics reaches 9.54 J/cm3 at 1394 kV/cm, which is 1.47 times that of dielectric glass ceramics crystallized at 750 °C. Moreover, glass ceramics exhibit a rapid discharge rate of approximately 0.237 μs and superior power density (2.39 MW/cm3) at 800 kV/cm. Significant enhancement in energy storage performance of the above ceramics is attributed to the component regulation and the reduction of interface polarization.

Process optimisation and kinetic study for esterification of levulinic acid and n‐butanol using sulfonated titania–zirconia heterogeneous catalyst

AbstractBackgroundButyl levulinate (BL) was produced by the esterification of levulinic acid (LA) and n‐butanol (BOH) using a sulfonated nanocomposite of titania–zirconia as catalyst. A full factorial design was employed for studying the effects of reaction time, mole ratio and catalyst loading on LA conversion.ResultsThe synthesised catalyst was subjected to various characterisation techniques such as X‐ray diffraction, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller measurements, thermogravimetric analysis, temperature‐programmed desorption and scanning electron microscopy–energy dispersive X‐ray analysis indicating the presence of a nanocrystalline structure with good surface area and good stability at the operating temperature. The experimental data were analysed using the response surface method, and a complete quadratic regression model was built. The LA conversion was 85.37% for the optimised reaction conditions of 1:7 mole ratio, a catalyst loading of 1 wt% and a reaction time of 5 h at 110 °C. Based on the Langmuir–Hinshelwood–Hougen–Watson model, a kinetic model was developed. The activation energy was found to be 20.4 ± 0.8 kJ mol−1 from an Arrhenius plot. Reusability and leaching results are also reported.ConclusionThe catalyst exhibited good reusability and stability. Sulfonated TiO2–ZrO2 used to catalyse the reaction between LA and BOH to produce BL has proved to be a good candidate as a green catalyst. The results presented play an important part in directing subsequent research and commercialisation activities aimed at valorising LA to fuel additive. © 2023 Society of Chemical Industry (SCI).

Impact of thermal shock on the R-curve and subcritical damage behaviour of flame-sprayed alumina compounds

An alumina rich Al2O3–ZrO2–TiO2 compound was used for the preparation of self-supporting parts via the rod flame spraying technology. The as-sprayed material was compared to self-supporting parts, fabricated from commercially available alumina rods. For both materials, the flexural strength, the fracture resistance, and the behaviour under subcritical loading was evaluated and compared, either before as well as after cold thermal shock. While the flexural strength and the subcritical damaging of both materials were basically affected through thermal shock in a similar manner, the Al2O3–ZrO2–TiO2 compound showed an outstanding behaviour in terms of its fracture resistance, which was only barely reduced after thermal shock quenching.

Nanoscale Phase Separations for Versatile Synthesis of Centimeter‐Sized Hierarchically Mesoporous Metal‐Oxide Films

Hierarchically porous metal‐oxide materials have immense potential for many fields, which are highly desired to tackle the limitations of mono‐porous architectures, and to combine the advantages of different pore scales. Herein, a simple small‐molecule‐assisted interfacial assembly strategy, which elegantly combines the mesoscale block copolymers (BCPs)‐directed coassembly and nanoscale phase separations of dicyandiamide (DCDA), is developed for the synthesis of centimeter‐sized inorganic metal‐oxide films with multiscale porosity. The synthetic approach is versatile and can be broadly applied for the fabrication of hierarchically mesoporous metal‐oxide films with single (TiO2, ZrO2, Al2O3) or binary components (TiO2–ZrO2 and TiO2–Al2O3) on various substrates ranging from 1D to 3D. The as‐prepared films possess ordered structures, uniform thickness, interconnected pores, highly crystallized frameworks, and high surface areas (>200 m2 g−1). As a proof of concept, the photoelectric device assembled by the hierarchically mesoporous TiO2 films (denoted as H–TiO2) shows excellent performance, including a high photocurrent of 0.68 mA cm−2 and outstanding stability. The presented method may provide new insight into the controllable synthesis of hierarchically porous materials.

Study of the catalytic wet air oxidation of p-hydroxybenzoic acid on a fresh ruthenium catalyst supported by different oxides

The catalytic wet air oxidation (CWAO) of p-hydroxybenzoic acid (p-HBA) was conducted in a batch reactor at 140 °C, and at a total air pressure of 50 bar over Ru-based catalysts. Four materials were selected as supports – TiO2, CeO2–TiO2, ZrO2–TiO2, and La2O3–TiO2 – all of which had mesopores in their texture and pollutant adsorption capacities. The supports were prepared by the sol-gel method, and then impregnated with 3 wt% of Ru precursor. Such characterization techniques as N2-sorption, XRD, XPS, H2–TPR, NH3-TPD, TEM, and HAADF-STEM were used to analyze the different solids. The correlation between catalytic activities and physicochemical properties was discussed. A significant specific surface area (SBET), a large amount of surface-active oxygen, and Lewis acidity sites were observed on cerium-containing catalysts (Ru/CeTi). Fresh Ru catalysts containing cerium showed higher activity than Ru/TiO2, Ru/ZrTi, and Ru/LaTi catalysts. It is assumed that the acidic sites and surface oxygen trap the p-HBA molecule, thus increasing the catalytic properties of the Ru particles which interact with the surface oxygen through the cerium redox process (Ce3+/Ce4+). As the presence of cerium increases surface-active oxygen, it inhibits the deposition of carbon on the surface of the Ru catalyst. The pseudo-second order (PSO) model adequately described the kinetic data of the p-HBA oxidation reaction using Ru catalysts.

Experimental investigation and thermodynamic evaluation of the ZrO2–TiO2–SrO system

In the present work, a series of ZrO2–TiO2–SrO ceramic samples were prepared through solid-state reactions, and the phase relationships at 1473 K were systematically characterized. For the TiO2–SrO binary system, the presence of Sr4Ti3O10 was confirmed and the binary system was reassessed through CALPHAD method by using both the latest experimental data and first-principles calculations. The thermodynamic parameters of the TiO2–SrO system were combined with those of the ZrO2–TiO2 and ZrO2–SrO systems, and a set of self-consistent thermodynamic parameters of the ZrO2–TiO2–SrO system was optimized according to our measurements. Finally, the isothermal sections at 1473 K and 1733 K, the vertical section of SrTiO3–SrZrO3 and the liquidus surface projection were calculated. The calculated results agree well with the available experimental data, which proves the self-consistency and reliability of the present thermodynamic database.

Soft molecularly imprinted nanoparticles with simultaneous lossy mode and surface plasmon multi-resonances for femtomolar sensing of serum transferrin protein

The simultaneous interrogation of both lossy mode (LMR) and surface plasmon (SPR) resonances was herein exploited for the first time to devise a sensor in combination with soft molecularly imprinting of nanoparticles (nanoMIPs), specifically entailed of the selectivity towards the protein biomarker human serum transferrin (HTR). Two distinct metal-oxide bilayers, i.e. TiO2–ZrO2 and ZrO2–TiO2, were used in the SPR–LMR sensing platforms. The responses to binding of the target protein HTR of both sensing configurations (TiO2–ZrO2–Au-nanoMIPs, ZrO2–TiO2–Au-nanoMIPs) showed femtomolar HTR detection, LODs of tens of fM and KDapp ~ 30 fM. Selectivity for HTR was demonstrated. The SPR interrogation was more efficient for the ZrO2–TiO2–Au-nanoMIPs configuration (sensitivity at low concentrations, S = 0.108 nm/fM) than for the TiO2–ZrO2–Au-nanoMIPs one (S = 0.061 nm/fM); while LMR was more efficient for TiO2–ZrO2–Au-nanoMIPs (S = 0.396 nm/fM) than for ZrO2–TiO2–Au-nanoMIPs (S = 0.177 nm/fM). The simultaneous resonance monitoring is advantageous for point of care determinations, both in terms of measurement’s redundancy, that enables the cross-control of the measure and the optimization of the detection, by exploiting the individual characteristics of each resonance.

Comparison of BCl3, TiCl4, and SOCl2 chlorinating agents for atomic layer etching of TiO2 and ZrO2 using tungsten hexafluoride

Recent advances in the semiconductor industry have created an exigency for processes that allow to deposit and etch material in conformal matter in three-dimensional devices. While conformal deposition is achieved using atomic layer deposition (ALD), conformal etching can be accomplished by thermal atomic layer etching (ALE) which, like ALD, proceeds via a binary sequence of self-limiting reactions. This study explores ALE of TiO2 and ZrO2 using WF6 as a fluorinating agent, and BCl3, TiCl4, or SOCl2 as a co-reactant. The effect of co-reactant chemistry was studied using atomic force microscopy, in situ ellipsometry, and in vacuo Auger electron spectroscopy measurements along with thermodynamic modeling. All three co-reactants exhibited saturation and etch rates increasing with temperature. At 170 °C, TiO2 can be etched using WF6 with BCl3, TiCl4, or SOCl2, and the etching proceeds at 0.24, 0.18, and 0.20 nm/cycle, respectively. At 325 °C, ZrO2 ALE can occur using these same reactants, proceeding at 0.96, 0.74, and 0.13 nm/cycle, respectively. A higher temperature is needed for ZrO2 ALE versus TiO2 because the ZrCl4 product is less volatile than the corresponding TiCl4. During ZrO2 and TiO2 etching using BCl3 or TiCl4, boron oxide or titanium oxide intermediate layers, respectively, were formed on the surface, and they were subsequently removed by WF6. In contrast, for ALE of TiO2 using SOCl2, a similar intermediate layer is not observed. This study broadens the understanding of co-etchants role during thermal ALE and expands the range of reactants that can be used for vapor etching of metal oxides.

Effect of the combination of inverse opal photon superficial areaic crystal and heterojunction on active free radicals and its effect on the mechanism of photocatalytic removal of organic pollutants

For the inverse opal photocatalyst, hydraulic pressure and other problems caused by the ordered structure of the inverse opal photocatalyst make it difficult for the pollutants to enter the structure quickly and effectively, so the effective control of its structure has become an urgent problem to be solved. Here, multi-heterojunction inverse opal structure catalyst with multi-level branched pore structure is prepared by the sol-gel method. The special three-dimensional dendritic porous structure solves the problem that a pollutant solution is difficult to effectively enter a skeleton with the traditional ordered inverse opal photocatalyst. This structure can also lead to the nanocrystallization of TZS powders, thus promoting the formation of the intermediate product ZrTiO4 and optimizing the heterogeneous interface in the TiO2–ZrO2 heterojunction, thereby successfully constructing the multi-heterostructure and effectively improving the redox ability. Furthermore, by adjusting the loading amount of TZS, the matching of the heterojunction and the inverse opal structure can be effectively controlled, the matching of the photonic band gap and the forbidden bandwidth can be effectively adjusted, and the degradation efficiency is greatly improved. This study provides a new idea for effective collaboration between multi-heterogeneous interfaces and 3D branch fractal structures.

Structural and dielectric investigation of thermal treated TiO2/ZrO2 composite thin films grown by chemical beam vapor deposition

TiO2/ZrO2 (TZ) composite binary oxides thin films were synthesized by Chemical Beam Vapor Deposition technique with a combinatorial approach, followed by annealed at 600 °C for 1 h. Three different element compositions were used in the composite films, with TiO2/ZrO2 ratio of ∼80/20, ∼70/30 and ∼60/40 at.%. X-ray diffraction analysis indicated that the Zirconium titanate crystalline phase was predominated in the TZ composite films, particularly those with higher concentration of ZrO2. The TZ film with ∼60/40 at.% exhibited a maximum dielectric constant of ∼35, a loss tangent of ∼3 and a low leakage current density of ∼1.7 × 10−9A/cm2. These results suggest that the synergistic combination of TiO2 and ZrO2 makes them a potential candidate for capacitor applications.

Studies on polyoxymethylene dimethyl ethers production from dimethoxymethane and 1,3,5-trioxane over [formula omitted

Polyoxymethylene dimethyl ethers (OMEs) with physical properties similar to those of diesel has received significant attention as green additives for soot emission suppression. Herein, series of SO42-/ZrO2–TiO2 catalysts were developed for OMEs production from dimethoxymethane (DMM) and 1,3,5-trioxane through sequential formaldehyde monomer insertion into CO bond of DMM. Not Lewis but Brønsted acid sites were identified to be active for the decomposition of 1,3,5-trioxane into formaldehyde unit, however, both of them are effective for the chain propagation of DMM via formaldehyde unit insertion into CO bond. Kinetic studies indicated each chain growth step exhibited the same parameters and activation barrier on corresponding Brønsted and Lewis acid sites due to the same reaction mechanism and very similar chemical structure of OMEs. Also, the catalytic stability investigation suggested the deactivation behavior was derived from the carbon deposition, and the decay factor could be exponentially correlated with the amount of coke accumulation.

Rational design of three-dimensional porous Ir-supported TiO2–ZrO2 microspheres for low temperature methane combustion

Construction of efficient and stable catalytic combustion materials for the removal of unburnt methane (CH4) is very critical for both applied environmental catalysis and basic materials research. Herein, a facile hydrothermal approach is designed for the fabrication of Ir/UTZX (Ir/TiO2–ZrO2) catalysts. The as-synthesized Ir/UTZX catalysts possess unique sphere morphology as well as electronic structure, leading to enlarged exposure of catalytic sites and enhancement of redox properties. As a result, the representative Ir/UTZ5 catalyst achieves a CH4 conversion of nearly 100% at 425 °C. Significantly, Ir/UTZ5 displays high long-term stability, with no obvious decrease of catalytic activity in the run of 120 h, which is much higher than those of Ir/TiO2 and Ir/ZrO2 catalysts. Our findings offer insights for designing highly efficient and stable catalysts for CH4 catalytic combustion.

Synthesis of Mixed-Phase TiO2–ZrO2 Nanocomposite for Photocatalytic Wastewater Treatment

The use of TiO2 nanoparticles for photocatalysis for the degradation of organic dyes under UV light for wastewater treatment has been widely studied. However, the photocatalytic characteristics of TiO2 nanoparticles are inadequate due to their UV light response and higher band gap. In this work, three nanoparticles were synthesized: (i) TiO2 nanoparticle was synthesized by a sol-gel process. (ii) ZrO2 was prepared using a solution combustion process and (iii) mixed-phase TiO2-ZrO2 nanoparticles were synthesized by a sol-gel process to remove Eosin Yellow (EY) from aqueous solutions in the wastewater. XRD, FTIR, UV-VIS, TEM, and XPS analysis methods were used to examine the properties of the synthesized products. The XRD investigation supported the tetragonal and monoclinic crystal structures of the TiO2 and ZrO2 nanoparticles. TEM studies identified that mixed-phase TiO2-ZrO2 nanoparticles have the same tetragonal structure as pure mixed-phase. The degradation of Eosin Yellow (EY) was examined using TiO2, ZrO2, and mixed-phase TiO2-ZrO2 nanoparticles under visible light. The results confirmed that the mixed-phase TiO2-ZrO2nanoparticles show a higher level of photocatalytic activity, and the process is accomplished at a high degradation rate in lesser time and at a lower power intensity.

Study of the Embryonic Toxicity of TiO2 and ZrO2 Nanoparticles

Currently, the widespread use of TiO2 and ZrO2 nanoparticles (NPs) in various industries poses a risk in terms of their potential toxicity. A number of experimental studies provide evidence of the toxic effect of TiO2 and ZrO2 NPs on biological objects. In order to supplement the level of knowledge and assess the risks of toxicity and danger of TiO2 and ZrO2 NPs, we decided to conduct a comprehensive experiment to study the embryonic toxicity of TiO2 and ZrO2 NPs in pregnant rats. For the experiment, mongrel white rats during pregnancy received aqueous dispersions of powders of TiO2 and ZrO2 NPs at a dose of 100 mg/kg/day. To characterize the effect of TiO2 and ZrO2 NPs on females and the postnatal ontogenesis of offspring, a complex of physiological and biochemical research methods was used. The results of the experiment showed that TiO2 NPs as ZrO2 NPs (100 mg/kg per os) cause few shifts of similar orientation in the maternal body. Neither TiO2 NPs nor ZrO2 NPs have an embryonic and teratogenic effect on the offspring in utero, but both modify its postnatal development.

Development and characterizations of Ag nanoparticles decorated TiO2-ZrO2 coatings as electrode material for supercapacitors

Supercapacitors are considered as newly developed auxiliary and clean supplies of power and energy for the next generation energy storage devices with significant impact in many fields. In the present investigation, Ag nanoparticles decorated over TiO2-ZrO2 films are used as the material for energy storage applications. The cyclic voltammograms of the proposed material show better specific capacitance values and robust cyclic stability. The results of the electrochemical measurements further show a strong double-layer electrical capacitance of ternary mixed oxides. The synergetic interaction among the components in the hierarchical nanostructured porous Ag@TiO 2-ZrO2 film guaranteed the good capacitive performance. The comparison between the TiO2-ZrO2 films and Ag decorated TiO 2-ZrO2 films bring out the strong interconnection between the constitution and composition of both systems and their properties. These results underline the exceptional electrical double layer capacitive behavior that is seen in porous ternary composite films with better surface area. Furthermore, such a simple and low-cost layer by layer assembly method with self-cleaning property can be used for the large-scale fabrication of diverse functional architectures for energy storage and conversions.

Wear behaviour of different nano particles coating on Al6061 substrate

ABSTRACT The tribological behaviour of Ni-based composite coatings on Al6061 substrate with secondary phase hard oxide particles like ZrO2, TiO2, and Al2O3 at different elevated temperature conditions was compared. The composite coatings with different reinforcement of nano particles were characterized by scanning electron microscopy and X-ray diffraction technique. The higher microhardness value is reported for the Ni coating with TiO2 particles and Al2O3 particles. At higher temperature limits of 120°C and 140°C Ni–ZrO2 coatings have found better specific wear rate. The Ni–Al2O3–TiO2–ZrO2 composite coating fails to achieve better properties due to higher agglomeration of the particles and dendrite growth. The Ni–Al2O3 coating showed steady wear behaviour at different temperature limits. The coefficient of friction values is found nearly similar for all the type coatings at 40°C and 120°C.

Co-dependency of TiO2 underlayer and ZrO2 top layer in sandwiched microwave-assisted Zr-Fe2O3 photoanodes for photoelectrochemical water splitting

We report the synergistic effect of ZrO2 top and TiO2 under layers on the microwave-assisted Zr-Fe2O3 photoanodes. The optimum TZF2ZQ exhibited 144.5 and 71.3 μmol of H2 and O2 evolution at 1.23 V vs. RHE.