Mixture Of TiO2 Research Articles

TWO-LEVEL MODEL OF COMPOSITE SYNTHESIS ON A SUBSTRATE FROM A POWDER MIXTURE OF TiO2 AND Al2 STRUCTURE OF THE REACTION ZONE IN A TWO-LEVEL MODEL OF COATING SYNTHESIS

Modern technologies of composite coatings synthesis often use chemically reacting mixtures in combination with moving high-energy heat sources. The chemical transformations that occur during this process can be divided into two groups. The first group leads to the formation of strengthening particles, the secondto the matrix composition formation. In this work, a two-level model of coatings synthesis with reduced scheme of chemical reactions is proposed. It is assumed that chemical reactions occur at the particle level, so the local volume of initial powders mixture is replaced by a conventional reaction cell. The averaged information is transferred to the macrolevel, where the temperature field is calculated. The possibility of calculating accompanying stresses and deformations of the second kind has been demonstrated. Different synthesis modes have been identified.

(Invited) Forming Multifunctional Ceramics with Different ZrO2 Polymorphs: Mixed Ion-Electron Conducting Properties of Zirconium Titanium Oxides

Infiltrating porous electrodes with solution phase precursors is a strategy employed to improve performance, catalytic activity and longevity in high temperature electrochemical devices. For example, traditional Ni yttria-stabilized zirconia (Ni-YSZ) cermet anodes used in solid oxide fuel cells (SOFCs) are susceptible to carbon accumulation and to sulfur poisoning. To counter the effects of degradation, anodes have been infiltrated with secondary materials containing Sn, Ba, Al and a host of other constituents, typically at levels of 1-5% (by mass). Processing and preparing infiltrated electrodes, however, can lead to formation of new material phases that affect surface chemistry and electrode microstructure in unexpected ways.In this work, XRD and Raman spectroscopy are used to investigate the formation of functional zirconium titanate secondary phases in Ti/Zr oxides. Different zirconia polymorphs (either pure or stabilized with small amounts of yttria (YSZ)) mechanically mixed with TiO2 and heated above 1000 ˚C in stagnant air react to form several secondary phases. For sintering temperatures > 1100 ˚C, mixtures of TiO2 and m-ZrO2 form a ZrTiO4 secondary phase while mixtures of TiO2 and 3YSZ or 8YSZ form Zr5Ti7O24. The extent of secondary phase formation is enhanced with both higher sintering temperature and yttria content. The Zr5Ti7O24 secondary phase formed from TiO2/8YSZ samples sintered at 1400 ˚C exhibits unexpected mixed ionic and electronic conductivity at 800 ˚C. These findings suggest that secondary phases intentionally integrated into electrode architectures can improve the performance of high temperature electrocatalyst systems.

TiAl-Based Oxidation-Resistant Hard Coatings with Different Al Contents Obtained by Vacuum-Pulse-Arc Granule Melting

A method was proposed for increasing the oxidation resistance of promising wrought Ti2AlNb ortho-alloys by depositing γ-TiAl-based coatings. Using original vacuum pulse-arc melting of 100 μm thick granule layers, coatings with different Al/Ti ratios and a thickness of 50–60 µm were obtained on the surface of the Ti50Al25Nb25 alloy. Granules Ti50Al44Nb4.9Mo1B0.1 (at.%), 20–60 μm in size, were employed. To vary Al content, initial granules and their mixture with Al powder were used. Excellent adhesion of the coatings is ensured by the similar chemical composition and structure of the substrate and coatings, as well as micro-metallurgical reactions between granules and the substrate that occur during treatment. The resulting coatings had a submicron gradient structure consisting of TiAl and Ti3Al intermetallic compounds. During oxidation at 850 °C for 10 h, an oxide layer consisting of a mixture of α-Al2O3, TiO2, and AlNbO4 was formed on the coating surfaces. With an increase in the annealing duration to 100 h, a dense α-Al2O3 oxide layer, approximately 0.5 µm thick, was formed over the primary oxide mixture, the quality of which was higher in coatings enriched with aluminum.

EFFECT OF h-BN AS AN ADDITIVE ON PHYSICAL AND MECHANICAL PROPERTIES OF Al2TiO5 COMPOSITE

Aluminum titanate (Al2TiO5) is a promising material for high-temperature applications due to its low thermal expansion, high melting point, and excellent corrosion resistance. In this study, the effect of h-BN addition on the properties of Al2TiO5 composites was investigated. The composites were prepared by sintering a mixture of Al2O3 and TiO2 at a 1:1 molar ratio, with varying amounts of h-BN (5-20 mol%) added to the mixture. The samples were sintered at 1,500ºC for 4 h in an N2 atmosphere, and the bulk density, porosity, phase transition, microstructure, flexural strength, and hardness of the composites were investigated. XRD analysis confirmed the presence of Al2TiO5, Al2O3, and Al18B4O33 phases in the composites. The addition of h-BN in increasing amounts from 5 to 20 mol% resulted in a gradual improvement in the bulk density, flexural strength, and hardness of the Al2TiO5 composites. The composite with the highest h-BN content (20 mol%) exhibited a bulk density of 3.12 g/cm3, as well as the highest flexural strength and hardness values of 123.6±8.9 MPa and 11.2±4.1 GPa, respectively.

Photoreforming of glycerol to produce hydrogen from natural water in a compound parabolic collector solar photoreactor

To improve TiO2 for H2 generation, one strategy for the separation of photogenerated charges is the formation of heterostructures with other materials. In particular, NiO is a photocatalyst known for its good stability and low cost. However, no studies at pilot scale using solar energy have been described. Consequently, an evaluation of a physical NiO:TiO2 mixture at pilot scale (25 L) with natural irradiation (2.10 m2 of sun-exposed surface) and with simultaneous glycerol photoreforming was explored. NiO:TiO2 50 mg·L−1 resulted in the highest hydrogen production, showing an STH = 1.44%, considering only the UV fraction of the solar irradiation. H2 and CO2 production were analysed by on-line GC; Glycerol, dissolved organic carbon, carboxylic acids and nickel leaching were also evaluated. The NiO:TiO2 mixtures rendered a systematically lower H2 production in natural water than in high-purity water. The increase of ionic strength increased the mean size of particle clusters, promoting rapid sedimentation. All this indicates the importance of testing under real field conditions for attaining reliable solar to hydrogen (STH) efficiency.

Characterization of Bismuth Titanate by Line Profile Analysis

Bismuth Titanate (BIT), Bi4Ti3O12, was synthesized using the solid-state reaction process from the oxide mixture of Bi2O3CO3 and TiO2. The characterization analysis of the prepared sample was done by X-ray diffraction technique. The X-ray diffraction data revealed an orthorhombic perovskite phase that was clearly explained. The Scherrer method, modified W-H analysis, and the SSP studies were conducted to figure out the crystallite size and micro strain in Bi4Ti3O12. Morphological studies included SEM and TEM analysis. FTIR spectral investigation supports the M-O coordination of the synthesized Bi4Ti3O12 sample. The phase formation patterns of Bi4Ti3O12 determined by different methods are highly connected.

Constructing multiple heterogeneous shell on the CaCu3Ti4O12 core for better dielectric performances

A core-shell synthesis is proposed in this study to improve the dielectric loss and the resistivity of CaCu3Ti4O12 (CCTO), which exhibits a colossal permittivity, make it very interesting for capacitor applications. However, the grain boundaries of this ceramic material play a key role for the good dielectric properties. To control these boundaries can be performed by producing shells around the CCTO grains with different oxide mixtures. The design of core-shell structure is a possible approach to control the thickness and homogeneity of the shell, which will improve the properties of this material. In this work, as-prepared CCTO particles, synthetized by solid-state reaction, were successful coated with double or triple shell (SiO2, Al2O3, TiO2) using conventional sol–gel processing derivative from Stöber method. This coating with several binary oxides is made for the first time and has an innovative character in the improvement of properties for an application The CCTO coated with shell composed of SiO2 + Al2O3 + TiO2 mixture showed the best improvement with a colossal permittivity about 7.104, low loss tangent close to 0.05 and high resistivity equal to 109 Ω cm at 1 kHz. Indeed, a clear increasing of resistivity and decreasing of dielectric loss were observed for these samples compared with the resistivity of CCTO (≈105 Ω cm). Moreover, simulations of impedance curves give the capacitance and resistivity of the grain boundaries, which confirm by their linear behavior that the global properties of this material depend on the behavior of the grain boundaries in agreement with the Internal Bayer Layer Capacitors model.

Study of the effectiveness of a ZnO–TiO2 formulation in the degradation of humic substances in mature leachate by solar photocatalysis Brazil

Treatment of landfill leachate is an important environmental issue, especially in developing countries such as Brazil. Advanced oxidation processes (AOPs) have been considered interesting treatment alternatives. In this study, ZnO–TiO2 mixtures were incorporated into a paint polymer matrix and fixed onto supports. Paints were applied by overlapping coat layers on plates, resulting in high film thickness (600 ± 80 µm). Treatment of mature leachate by an AOP was conducted in a plug flow reactor connected to a stirred tank under solar irradiation. The objective was to evaluate the degradation of humic acid (HA) and fulvic acid + humins (FAH). The highest HA and FAH removal efficiencies were 62% ± 4.9% and 16% ± 4.2%, respectively. The kinetic model provided a coefficient of determination (R2) of 0.974. Rate constants for HA and FAH removal were 2.96 and 1.03 × 10−3 min−1, respectively. Statistical models for HA and FAH degradation had R2 values of 0.96 and 0.99, respectively. Both approaches indicated that HA degradation is greater at acidic pH and higher TiO2 concentrations. FAH degradation was favored by acidic pH and higher ZnO concentrations. Statistical models showed the same mean difference in conversion between replicate runs of HA and FAH, suggesting a uniform diffusion of fractions through catalysts.
 Keywords: heterogeneous photocatalysis, humic and fulvic acid, landfill leachate treatment, titanium dioxide, zinc oxide.

Influence of nano additive blended watermelon seed biodiesel on the performance and exhaust emissions of a VCR compression ignition engine

An innovative idea have been proposed in this work, to increase fuel efficiency and minimize emission from Diesel engine. This research mainly focuses on the systhesis of two nano materials namely MgO, TiO2. The synthesized nano additives was blended in equal proportion with Biodiesel prepared from Watermelon seed oil through the process of trans-esterification. Then 20% Biodiesel was mixed with 80% diesel and now the fuel is called as B20. Equal proportion of MgO and TiO2 mixture was prepared which is called as Nano Additive Mix(NAM) and added with B20 blend. A 5HP mono Barrel Diesel engine was powered with B20 and with various proportion of NAM in the range of 50ppm, 100ppm, 150ppm and 200ppm. The results obtained revealed that B20 blended with NAM150 minimized CO, HC and Smoke emission considerably when equated to other mixtures. The BTE at peak load for Diesel was 28.4% and for the same load it was 28.2% for B20 @ NAM150 blend. The B20 with 150NAM blend become the best alternative fuel combination to operate the engine with less emission and best fuel consumption and power output.

Synthesis and crystal structure of a novel quaternary Zr3TiSiC3 MAX phase

A novel quaternary 413-type Zr3TiSiC3 MAX phase has been synthesized in 97% yield by the vacuum carbosilicothermic reduction (VCSTR) method using mixtures of TiO2, ZrO2, SiC, and C powders as starting materials. The crystal structure of the synthesized Zr3TiSiC3 was studied by X-ray diffraction Rietveld analysis. The lattice constants of Zr3TiSiC3 MAX phase were a = 0.328292(5) nm and c = 2.39651(6) nm. It was revealed that the distribution of Zr and Ti atoms was fairly uniform in the basal plane of lattice, but was markedly inhomogeneous along the c-axis, with Zr atoms preferentially occupying the inner layers in the [M4X3] blocks rather than outer layers. The occupations of the outer and inner layers by Zr atoms were found to be approximately 67.4% and 82.6%, respectively, indicating a rather poor chemical ordering of Zr and Ti atoms in metal sublattice of Zr3TiSiC3 MAX phase.

Improving the thermophysical aspects of innovative clay brick composites for sustainable development via TiO2 and rGO nanosheets

In the current work, distinctive nanoscale fillers, such as reduced graphene oxide (rGO) and titanium oxide (TiO2), were synthesized to open up novel opportunities to enhance the thermal performance of clay brick composites. Innovative clay-based nanocomposite bricks with various doping levels, including untreated clay, clay–rGO, clay–TiO2 and clay–rGO–TiO2, were synthesized for the first time to enhance brick's thermophysical performance. Physical observations of microstructure, shrinkage, morphology, density, porosity, as well as thermophysical characteristics of the composite clay bricks were investigated. Incorporating a varying quantity of rGO and TiO2 nanoparticles (NPs) into the clay matrix resulted in a variation in peak intensity within the lattice structure, along with a rise in the estimated crystallite size to 30.3 nm of clay–rGO–TiO2 composites. Meanwhile, the wealthy hydroxyl groups of TiO2 and rGO NPs boost the formation of many hydrogen bonds well distributed within clay structures, leading to rigid filler adherence. Moreover, the apparent porosity rose (i.e. from 24.01% to 43.64%) due to the creation of new intermolecular covalent bonds and hydrogen bonds between clay–H2O and metal oxides–OH groups. This porosity results in lighter bricks (i.e. bulk density decomposes from 2.02 to 1.41 g/cm3) with a pore size on the order of 3.5 µm. These variations are supported by the differ-dense microstructure presented in the SEM images. Interestingly, the Clay–rGO–TiO2 mixture not only has a high thermal conductivity value (0.44 W/mK), but also exhibits exceptional thermal diffusivity (4.1 mm2/S). The existence of TiO2 NPs, along with rGO nanosheets with a large surface area and high porosity features, which efficiently permits liquid absorption of the interlayers is the main explanation for these findings.

Modeling and analysis of Bödewadt hybrid nanofluid flow triggered by a stretchable stationary disk under Hall current

In the recent era of science and technology scientists have influenced by the hybridization of nanofluids due to their advanced thermophysical features. Hybrid nanofluids have superior response to thermal conductivity than any other conventional nanofluids. Therefore, the present study investigates the Bödewadt flow of hybrid nanoliquid above a stretchable static disk located in the plane z=0. Bödewadt flow describes a stable and uniform angular rotation of liquid at a higher distance from the static disk. Such flow is characterized through pressure gradient in radial direction and is balanced with centrifugal forces. An incompressible homogeneous electrically conducting flow occupies its space at z≥0. Hybrid nanofluid is a mixture of nanoparticles Cu (copper) and TiO2 (titanium dioxide) with water considered as a base-fluid. Titanium dioxide reveals excellent photo catalytic attributes and hence is implemented in antibacterial/antiseptic compositions. Moreover, copper nano-ingredients metallic particles suggest suitable dye diminution and catalytic potential properties. Hall effect is encountered in the momentum equations to measure the magnetic field while radiation term is considered to address the energy analysis. The convective flow phenomenon is normalized by executing similarity functions. The reduced governing system is then solved in numerical manner using Runge-Kutta-Fehlberg (RKF-45) procedure. The flow phenomenon on velocity and thermal fields is discussed in graphical way. Three-dimensional flow visualization with two-dimensional contours and streamlines are portrayed as well. Moreover, the numeric data of local-Nusselt number shear stresses is computed against selected values of the physical parameters. The modification in Hall current magnifies the radial velocity field and reduces the velocity field along axial direction. The temperature field is enhanced by the increased variations in heat transfer Biot number. The influence of volume fractions results in modification of thermal profiles.

Glassy Carbon Electrode Modified with CB/TiO2 Layer for Sensitive Determination of Sumatriptan by Means of Voltammetry and Flow Injection Analysis

Sumatriptan is an organic chemical compound from the tryptamine group. It is used as a medicine for migraine attacks and in the treatment of cluster headaches. In this work, a new voltammetric method is proposed for highly sensitive SUM determination, using glassy carbon electrodes modified with carbon black and titanium dioxide suspension. The novelty of the presented work is the usage of the mixture of carbon black and TiO2 as glassy carbon electrode modifier for the first time for SUM determination. The mentioned sensor was characterized by great repeatability and sensitivity of measurements, which resulted in the obtention of a wide range of linearity and a low detection limit. The electrochemical properties of the CB-TiO2/GC sensor was characterized using the LSV and EIS method. The effect of different factors on the SUM peak, such as supporting electrolyte type, preconcentration time and potential, or influence of interferents, were tested using the square wave voltammetry technique. The linear voltammetric response for the analyte was obtained in the concentration range of 5 nmol L−1 to 150 μmol L−1 with a detection limit of 2.9 nmol L−1 for a preconcentration time of 150 s in the 0.1 mol L−1 phosphate buffer pH 6.0. The proposed method was successfully applied for highly sensitive sumatriptan determination in complex matrices, such as tablets, urine, and plasma, with a good recovery parameter (94–105%). The presented CB-TiO2/GC electrode is characterized by great stability, it was used for 6 weeks without significant changes in the SUM peak current. Amperometric and voltammetric measurements of SUM under the flow injection conditions were also performed to indicate the possibility of its fast and accurate determination with a time of single analysis of approx. 30 s.

Preparation and cooling performance analysis of double-layer radiative cooling hybrid coatings with TiO2/SiO2/Si3N4 micron particles

Passive daytime radiative cooling is achieved by radiating heat into outer space through electromagnetic waves without energy consumption. A scalable double-layer coating with a mixture of TiO2, SiO2, and Si3N4 micron particles for radiative cooling is proposed in this study. The finite-difference time-domain algorithm is used to analyze the influence of particle size and coating thickness on radiative cooling performance. The results of the simulation show that the particle size of 3 μm can give the best cooling performance, and the coating thickness should be above 25 μm for SiO2 coating. Meanwhile, the mixture of SiO2 and Si3N4 significantly improves the overall emissivity. Through sample preparation and characterization, the mixture coating with a 1:1 ratio addition on an Al substrate exhibits high reflectivity with a value of 87.6% in the solar spectrum, and an average emissivity of 92% in the infrared region (2.5 μm–15 μm), which can be attributed to the synergy among the optical properties of the material. Both coatings can theoretically be cooled by about 8 °C during the day and about 21 °C at nighttime with h c = 4 W⋅m−2⋅K−1. Furthermore, even considering the significant conduction and convection exchanges, the cooling effect persists. Outdoor experimental results show that the temperature of the double-layer radiative cooling coating is always lower than the ambient temperature under direct sunlight during the day, and can be cooled by about 5 °C on average, while lower than the temperature of the aluminum film by almost 12 °C.

Optical, structural and mechanical properties of TiO2 and TiO2-ZrO2 thin films deposited on glass using magnetron sputtering

In this study, the structural, optical, and mechanical properties of magnetron sputtered TiO2 and TiO2-ZrO2 mixture transparent thin films along with the effect of heat treatment were investigated. TiO2 and TiO2-ZrO2 thin films were fabricated by magnetron sputtering from ceramic targets at room temperature on both the soda-lime and the borosilicate glass substrates. Structural properties of thin films were studied via X-ray photoelectron spectroscopy (XPS), grazing incidence X-ray diffractometry (GI-XRD) and scanning electron microscopy (SEM). Optical characterizations were carried out using spectrophotometry and spectroscopic ellipsometry. The hardness and scratch behavior of the samples were investigated using nano-indentation and nano-scratch tests. TiO2 and ZrO2 presence in films was confirmed by XRD and XPS analysis. It was found that TiO2-ZrO2 films show higher hardness values compared to TiO2 thin films. It was also seen that ZrO2 presence in TiO2-ZrO2 thin films prevents the crystallization of TiO2 after annealing compared to TiO2 thin films that resulted in better surface quality and higher thermal stability after annealing. The addition of ZrO2 to TiO2 resulted also in the shifting of the absorption edge to smaller wavelengths while decreasing the sharpness thus providing less absorption in the visible area, especially in the range of 380–500 nm. The refractive index of TiO2-ZrO2 thin film remained relatively unchanged compared to TiO2 after annealing, making it more preferable in terms of optical stability.

Microstructure and mechanical properties of (Zr,Ti)B2–SiC composites obtained by pressureless sintering of ZrB2–SiC–TiO2 powder mixtures

Multiphase ceramics have been highlighted due to the combination of different properties. This work proposes to obtain the multiphase composite of (Zr,Ti)B2–SiC based on the mixture of ZrB2, SiC, and TiO2 sintered without pressure. The effect of TiO2 addition on solid solution formation with ZrB2, densification, microstructure, and mechanical properties was investigated. For this, 2.0 wt% TiO2 was added to ZrB2–SiC composites with 10–30 vol% SiC and processed by reactive pressureless sintering at 2050 °C with a 2 h holding time. Sinterability, crystalline phases, microstructure, Vickers hardness, and indentation fracture toughness of these composites were analyzed and compared to the non-doped ZrB2–SiC samples. The XRD analysis and EDS elemental map images indicated the incorporation of Ti atoms into the ZrB2 crystalline structure with solid solution generation of (Zr,Ti)B2. The addition of TiO2 resulted in matrix grain size refinement and a predominant intergranular fracture mode. The relative densities were not significantly modified with the TiO2 addition, though a higher weight loss was detected after the sample sintering process. The composites doped with TiO2 showed an increase in fracture toughness but exhibited a slightly lower Vickers hardness compared to composites without TiO2 addition.

A Study on TiO2-CeO2 nanocomposite coatings for corrosion protection of 304LN stainless steel

Nano composite coatings are used to modify the substrate properties for a better life of the structures exposed to saline environments. Using a method known as spin coating, the authors of this study coated 304LN stainless steel with a mixture of TiO2 and CeO2 nano particles. The ratio of TiO2 to CeO2 in the coatings was 1:5:10:20 by weight percent. Stainless steel 304 was used as a substrate for the deposition of coatings since it is reasonably affordable. The effect that 3.5 weight percent NaCl solution had on the wett ability of the coating and its resistance to corrosion was investigated. The end effect is improved corrosion resistance in line with the rising coating weight percentage. After being exposed to the solution for 600 hours, the corrosion was significantly decreased. X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled to energy dispersive spectroscopy were used to investigate the deposits (EDS). The nano composites’ inherent physical features ensure their continued presence on the surface. The ratio of surface area to volume is satisfactory. According to the contact angle, the amount of water that is spreading out is extremely little. The photo produced cathodic protection feature of the TiO2-CeO2 coating is shown by the results of spin coating methods applied on 304LN stainless steel that was previously coated with TiO2-CeO2. After being subjected to the corrosion test, the coating made of 10% TiO2-CeO2 exhibited no signs of pitting or pinholes. The structural equation modeling (SEM) studies backed this conclusion. When it comes to the resistance to corrosion, the results produced by the contact angle are better. As a consequence of this finding, it was concluded that the coating could withstand the NaCl attack.

Dry synthesis of brannerite (UTi2O6) by mechanochemical treatment

Abstract A powder mixture of UO2 and TiO2 was mechanochemically treated in a planetary ball mill under Ar atmosphere for 1 h using a tungsten carbide vial and balls as the milling medium. Such mechanochemical (MC) treatment reduced the crystallinity of UO2 and TiO2. The mechanochemically treated powder mixture was heated at 700–1,300°C for 6 h under Ar atmosphere and analyzed by X-ray diffraction analysis, scanning electron microscopy-energy-dispersive X-ray spectroscopy, and X-ray absorption fine structure analysis. For comparison, a UO2 and TiO2 mixture without MC treatment was heated and analyzed under the same conditions. UTi2O6 did not form below 1,100°C without MC treatment and only the starting materials were observed. At 1,200 and 1,300°C, a small amount of UTi2O6 and equal amounts of UTi2O6 and UO2 were formed, respectively. The mechanochemically treated sample produced nearly pure UTi2O6 containing small amounts of UO2 impurities when heated above 900°C for 6 h. UTi2O6 was highly crystalline and uniform regardless of the synthesis temperature. It is suggested that the crystallinity of UO2 and TiO2 was reduced and the formation of UTi2O6 was promoted by MC treatment.

Metabolomics and transcriptomics reveal the toxic mechanism of Cd and nano TiO2 coexposure on rice (Oryza sativa L.)

Engineered nanoparticles (ENPs) can resist heavy metal toxicity in plants, but their coexposure still exhibits toxicity to plants compared to plants without exposure to ENPs and heavy metals. There have been few studies on the toxic mechanism of nano TiO2-heavy metal coexposure and the effect mechanism of nano TiO2 in plants. Thus, transcriptomics and metabolomics were used to study the toxic mechanism of rutile nano TiO2 or TiO2-Cd (rutile nano TiO2 and CdCl2 mixture) on rice (Oryza sativa L.). After 40 days of exposure, the plant height and root dry weight of rice were significantly decreased in the nano TiO2-Cd group compared to the blank group (nano TiO2 and CdCl2 free). After Cd treatment, 423 differentially expressed genes (DEGs) and 16 differential metabolites were identified. Nano TiO2 exposure induced significant regulation of 299 DEGs and 6 metabolites. After nano TiO2-Cd coexposure, 1660 DEGs and 181 differential metabolites were identified. Notably, the EDGs (e.g., chalcone isomerase and hydroxycinnamoyl transferase) and differential metabolites (e.g., chrysin and galangin) demonstrated the disruption of flavonoid biosynthesis in Cd-treated rice. After rice was exposed to nano TiO2, the DEGs were related to ribosome, whereas the differential metabolites were associated with pyruvate metabolism and valine, leucine, and isoleucine biosynthesis. Furthermore, 14 DEGs (e.g., asparaginyl-tRNA synthetase and methionyl-tRNA formyltransferase) involved in aminoacyl-tRNA biosynthetic pathways were significantly upregulated in rice treated with nano TiO2-Cd, in line with the changes in related metabolites (e.g., L-asparagine and 10-formyltetrahydrofolate). Our results show that it is necessary to pay close attention to the toxicity of nano TiO2-Cd coexposure in paddy ecosystems and use ENPs with caution to combat the phytotoxicity of heavy metals.

The effect of non-equimolar doping on the preparation and electrical conductivity of Sr(Ti,Zr,Zn,Sn,Hf)O3-σ high entropy perovskite oxide

A series of high entropy oxides (HEOSs) with non-isomolar ratios of perovskite structures were prepared by ball milling a mixture of SrO, TiO2, ZrO2, ZnO, SnO2 and HfO2 followed by sintering using a high-temperature solid-phase method. Both XRD and TG-DSC results indicate that single-phase Sr(Ti0.2Zr0.2Zn0.2Sn0.2Hf0.2)O3-σ is formed at 1500 °C. According to the SEM-EDS pictures, the elements in the oxide are uniformly distributed with no significant segregation or accumulation. The TEM results show that the polycrystalline ceramic powders can be classified as orthogonal Pbnm perovskite structure. The electrical conductivity (σ) was measured by the EIS technique and the activation energy (Ea) of HEOSs is calculated. In the temperature range of 300–750 °C, Sr(Ti0.28Zr0.18Zn0.18 Sn0.18 Hf0.18)O3-σ exhibits the highest conductivity (2.41 × 10−3 S/cm) and the lowest activation energy (Ea = 0.57 eV) due to lattice distortion and oxygen vacancy concentration.