O2 Samples Research Articles

Oxidative dissolution of (U,Ce)O2 materials in aqueous solutions containing H2O2

Homogeneous and heterogeneous U1-xCexO2 (with 0≤ x≤ 0.25) materials were prepared via wet and dry chemistry routes, respectively before being submitted to dynamic leaching experiments. The feeding solution containing 0.20 mmol.L−1 H2O2 was kept under air and renewed to guarantee the stability of H2O2 during the experiment. Normalized alteration rates were determined from U concentration in the leachates. For homogeneous (U,Ce)O2 materials, the dissolution rate was divided by a factor of 3 when increasing the Ce content from 0.08 to 0.25. Surface characterizations revealed that studtite precipitated all over UO2 pellet surface and only on the UO2 grains of heterogeneous U0.92Ce0.08O2 samples. The behaviour of this heterogeneous material was similar to that observed for (U,Pu)O2 in the same conditions, which revealed the reliability of cerium as a plutonium analogue.

Gamma-radiation hardness and long-term stability of ALD-Al2O3 surface passivated Si

Al2O3 has emerged as the surface passivation material of choice for p-type silicon in photovoltaics and has also become a candidate for passivating Si-based radiation sensors. However, the surface passivation of Al2O3 has been shown to degrade when exposed to gamma-radiation, making it of interest to determine methods of depositing Al2O3 that minimize the radiation-induced degradation on the surface passivation. In this study, we investigate the long-term stability and gamma-radiation hardness of Al2O3 prepared using the TMA+H2O+O3 precursor combination and how the pretreatment, the deposition temperature, and the film thickness affect the density of interface states, Dit, and fixed oxide charge, Qfix, before and after gamma-irradiation. We find that the surface saturation current density, J0s, of silicon passivated by Al2O3 increases after annealing but stabilizes over time depending on the Al2O3 thickness. Samples with thicknesses of <20 nm stabilize within hours, while those with >60 nm stabilize over days. J0s stabilizes at lower values with increased Al2O3 thickness. After exposure to 1 Mrad gamma-radiation, the samples still exhibit low Dit and high Qfix, with the best performing sample having a Dit of 1.5 × 1010 eV−1 cm−2 and a Qfix of −3.1 × 1012 cm−2. The deposition temperature appears to indirectly affect radiation hardness, owing to its impact on the hydrogen concentration in the film and at the Si–SiOx–Al2O3 interface. Lifetime measurements after irradiation indicate that Al2O3 still passivates the surface effectively. The carrier lifetime and Qfix can largely be recovered by annealing samples in O2 at 435 °C.

Sodium doped SrTi1-xBxO3 (B[dbnd]Mn, Co) for formaldehyde catalytic oxidation: Flame spray pyrolysis fabrication and reaction mechanism elaboration

Perovskite oxides are considered to be cheap replacement for precious metal catalysts thanks to its outstanding stability and adjustable catalytic activity. However, the high-demand preparation process still impedes the utilization of catalytic oxidation on perovskite material. Herein, the flame spray pyrolysis (FSP) technology has been utilized to successfully prepare the alkali metal and transition metal co-doped SrTiO3 perovskite catalyst for excellent formaldehyde catalytic performance. The results demonstrate that, compared with alone cobalt dopant, the perovskite doping with Na and Co exhibits significantly larger specific surface area (SSA), better low-temperature reducibility, higher adsorbed oxygen ratio and Co element dispersion, all of which extremely promote the formaldehyde oxidation activity. Additionally, by raising the dispersed gas flow rate to 6 mL/min, Sr0.9Na0.1Ti0.5B0.5O3 presents more outstanding activity of HCHO oxidation reaction. Interestingly, Na doped SrTi0.5Co0.5O3 sample can dramatically enhance formaldehyde catalytic oxidation thermodynamically and kinetically.

Effect of Dy replacing Fe on microstructure, electrical properties, and magnetic properties of NiZnCo ferrite

Considering how quickly wireless communication has developed, the need for the miniaturization, integration and high frequency of electronic components is more intense. The improvement of material properties is the key to solving the difficulties in the development of electronic devices. Solid-phase reactions were used to create Ni0.5Zn0.4Co0.1DyxFe2-xO4 (NZCDF, 0 ≤ x ≤ 0.1) ferrite ceramics. The produced NZCDF ceramic samples are discovered to still have a spinel structure. The lattice constant a and bulk density dBulk increase when dysprosium ion is added. The saturation magnetization decreased from 82 to 71 emu/g, and the Hc increased from 18 to 23 Oe. Dysprosium can be added to ceramic samples to modify their level of polarization, lower their ε′, and minimize their dielectric loss. The DC resistance ρ increases to 6.3 × 103 Ω⋅m. In the higher frequency range, with the increase of dysprosium ion content, the magnetic quality factor Q increases significantly, its peak value expands, and its corresponding frequency shifts to a higher frequency. In the high-frequency region, the magnetic quality factor Q rises dramatically, its peak value expands, and its corresponding frequency shifts to a higher frequency. The peak Q of the Ni0.5Zn0.4Co0.1Dy0.1Fe1.9O4 sample increased to 14.71, and the frequency corresponding to the peak Q increased to 35.08 MHz. In short, substituting dysprosium ions for nickel-zinc-cobalt ferrite broadens the application range of ferrite ceramics in high-frequency devices. The spectrum of applications for ferrite ceramics in high-frequency devices is expanded by substituting rare earth dysprosium ions for NiZnCo ferrite ceramics.

Surface Modification and Mechanical Properties Improvement of Bamboo Fibers Using Dielectric Barrier Discharge Plasma Treatment.

The effect of argon (Ar) and oxygen (O2) gases as well as the treatment times on the properties of modified bamboo fibers using dielectric barrier discharge (DBD) plasma at generated power of 180 W were investigated. The plasma treatment of bamboo fibers with inert gases leads to the generation of ions and radicals on the fiber surface. Fourier transform-infrared spectroscopy (FTIR) confirmed that the functional groups of lignin and hemicellulose were reduced owing to the removal of the amorphous portion of the fibers by plasma etching. X-ray diffraction analysis (XRD) results in an increased crystallinity percentage. X-ray photoelectron spectroscopy (XPS) results showed the oxygen/carbon (O/C) atomic concentration ratio increased with increasing treatment time. The fiber weight loss percentage increased with increased treatment time. Scanning electron microscopy (SEM) images showed that partial etching of the fiber surface led to a higher surface roughness and area and that the Ar + O2 gas plasma treatment provided more surface etching than the Ar gas treatment because of the oxidation reaction of the O2 plasma. The mechanical properties of fiber-reinforced epoxy (FRE) matrix composites revealed that the F(tr)RE-Ar (30) samples showed a high tensile strength, whereas the mechanical properties of the F(tr)RE-Ar + O2 sample decreased with increased treatment time.

Unveiling the role of Ni doping in the electrochemical performance improvement of the LiMn2O4 cathodes

Ni doping is a commonly used strategy to improve the electrochemical performance of LiMn2O4. Uncovering the structural changes of Ni-doped LiMn2O4 during electrochemical cycling, particularly at the atomic level, is important to understand the mechanism of the relationship between Ni doping and performance improvement. Herein, we investigate the chemical and structural evolutions of the Ni-doped LiMn2O4 electrodes before and after 1000 cycles at 10 C with atomic resolution and correlate them with changes in the electrochemical properties. We found that Ni2+ ions doped into the Mn 16d sites to form a more steady LiNixMn2-xO4 phase construction, which can effectively stabilize the spinel structure by hindering Jahn − Teller distortion. Comprehensive atomic imaging demonstrated that Ni doping can suppress the formation of the unexpected Mn3O4, and rock-salt MnO phases on the surface and subsurface of LiMn2O4 during cycling, which is conducive to stabilizing the MnO6 octahedron and inhibiting the migration of Mn. Resultantly, splendid long cycling stability of 88.92 % after 1000 cycles at 10 C (1 C = 148 mAh g−1) for the optimized LiNi0.05Mn1.95O4 sample is presented. Our study provides an ingenious avenue for regulating the surface optimization and reconstruction of electrode materials.

Novel incomplete phase transition from α-Bi2O3 to γ-Bi2O3 constructing dual interfaces contacts with BaTiO3 for highly efficient degradation of antibiotics

Incomplete lattice transition in heterojunction preparation can generate another crystal phase to provide a new transfer channel of electrons and holes for enhancing photocatalytic activity. In this paper, the hydrothermal synthesis of BaTiO3 and α-Bi2O3 composite induced a part of α-Bi2O3 to γ-Bi2O3 lattice transition. Except for α-Bi2O3/BaTiO3 interface, a new BaTiO3/γ-Bi2O3 contact was formed to realize another transfer channel of the charge carriers. The removal efficiencies of norfloxacin and lomefloxacin using the optimal α-Bi2O3/BaTiO3/γ-Bi2O3 sample reached 93% and 95%, much higher than those of the pure phases and the diphasic heterojunction samples. After five times of cycle tests, the photodegradation efficiencies of these two antibiotics were above 90% and 91%, respectively, while the crystal structure of the sample unchanged to exhibit good structure stability. The superoxide radical (O2−), hole, and hydroxyl radicals (OH−) were the main active substances upon the antibiotics degradation. The photocatalytic enhancement mechanism was originated from the formation of a new Z-type energy band according to the surface and interface calculation. Finally, the analysis of mass spectrometry revealed the degradation processes of these two pollutants. These results provided a simple way to obtain efficient double interfaces heterojunction photocatalysts for removing antibiotic pollutants.

Structural and surface morphological investigation of Ni- doped NdMnO3 perovskite nanomaterial

The solid-state reaction method was used to create a nanocrystalline NdMn0.7Ni0.3O3 sample. The orthorhombic crystal structure with the Pbnm space group was confirmed by Rietveld refinement fitting of the X-ray diffraction data using the FullProf tool. Bond lengths and bond radii were calculated together with other structural characteristics. Micrographs taken with a scanning electron microscope (SEM) at various magnifications reveal consistency across the sample, and a particle size estimate in the micron range. The EDX spectrum shows that the sample is completely free of contaminants. Using UV–Vis absorption spectroscopy and Tauc's plot, energy bandgap is found to be 2.59 eV. The crystallite size calculated by Scherrer method is obtained to be 38 nm.

Boosting energy-storage performance in lead-free ceramics via polyphase engineering in the superparaelectric state

Dielectric energy storage devices are important components of high-power and pulsed electronic systems. High recoverable energy density (Wrec) and high efficiency (ƞ) are critical parameters for such applications. In this work we propose a strategy of polyphase engineering in the superparaelectric (SPE) state to achieve high-performance energy storage. Through careful engineering of the proportions of rhombic (R) phase and tetragonal (T) phase by a linear dielectric additive, CaTi0.8Hf0.2O3 (CTH), in 0.94Na0.5Bi0.5TiO3-0.06BaTiO3-based ceramics, the SPE state can be shifted to ambient temperature when R/T ≤ 0.16. Thanks to the features of isolated polar nano-domains (PNRs) and the fine P-E hysteresis loop of the SPE state, an ultrahigh Wrec of 8.91 J/cm3 and high ƞ of 78.4% are achieved in our 0.75(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-0.25CaTi0.8Hf0.2O3 sample. The sample was also characterized by excellent temperature and frequency stability, achieving ultra-high power density (178 MW/cm3) and ultra-fast transient discharge time (40 ns). Our work proves that polyphase engineering in the SPE state is a powerful approach to the design of dielectric energy storage materials with high performance.

Engineering of efficient visible light photocatalysts: Ti1–x+yCuxLayO2 (x = 0.03; y = 0, 0.005, 0.01) compositions

In dye-photocatalysis, widening the wavelengths absorption range of catalysts as well as aborting the recombination of the photoexcited charge carriers (electrons–holes pairs) are of paramount significance. In the current study, we report the photocatalytic characteristics of four compositions composed of TiO2, Ti0.97Cu0.03O2, Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 powders for two harmful dyes (Congo red and methylene blue). The X-ray diffraction technique verified the configuration of mixed anatase and rutile phases in pure TiO2 and Ti0.97Cu0.03O2 powders while Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 powders possess anatase phase only. The changes of the band gap structure and dimensions of the unit cell volume of TiO2 confirm the substitution of Ti4+ sites by Cu2+ and La3+ ions. Remarkable widening of wavelengths absorption with formation of long absorption tails were found in TiO2 (3.13 eV) through insertion of La3+ plus Cu2+ ions. Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 samples exhibit a visible light band gap of 2.3 and 2.7 eV, respectively. Based on SEM images, incorporation of Cu2+ and La3+ ions influences the surface morphology of TiO2. The resulting Ti0.97Cu0.03O2, Ti0.965Cu0.03La0.005O2 and Ti0.96Cu0.03La0.01O2 powders present enhanced photocatalytic activity towards Congo red dye degradation compared to pure one under natural solar spectrum. The best Ti0.96Cu0.03La0.01O2 catalyst exhibits superior photocatalytic activity of 96% for 10 ppm CR dye in 20 min as well as above average photocatalytic efficiency of 63% for 30 ppm CR dye in 120 min. As well, it showed acceptable photodegradation activity of 52% for 30 ppm MB solution in 140 min of sunlight irradiation. The heightened photodegradation efficiency of Ti0.96Cu0.03La0.01O2 catalyst can be clarified in terms of higher charge carriers’ separation (Cu2+ + e– → Cu+, La3+ + e– → La2+), oxygen vacancies, full anatase phase structure as well as the wide range of visible light absorption.

Synthesis and Characterizations of Gd1.99Ce0.01O3 Phosphors

The present research aims to study the structural, morphological and bandgap studies of 1mol% Ce doped Gd2O3 samples. Gd1.99Ce0.01O3 sample was synthesized via hydrothermal method. The crystallinity, phase and crystallite size are determined using X-ray diffraction (XRD) patterns. X-ray diffraction patterns revealed the development of pure crystalline phase Gd2O3 sample. The morphology of the synthesized sample is examined using Field emission scanning electron microscope (FESEM) micrographs and elemental composition by energy dispersive spectroscopy (EDS) spectra. FESEM results confirmed the formation of rod shape of the synthesized samples. The bandgap studies are done using UV-Visible spectroscopy. The synthesized samples are the potential candidates for various biomedical, and optoelectronic applications.

Effect of La and Se in tailoring the energy storage properties of BFO nanostructures

Simultaneous rare-earth doping at A and B sites have impacted various properties of BFO at room temperature. In this work, the dielectric and magnetic properties of BFO, are tailored by doping La and Se. Bi0.92La0.08Fe1−xSexO3, (x = 0%, 10%, 25%, 50%, 100%) nanostructures are prepared using sol-gel technique. Structural analysis reveals that increased doping has reduced and eliminated the secondary phases of nanostructures. Absorption spectra showed a wide blue shifted absorption, indicating multiple electron transitions and the bandgap values decreased upon doping. Improved room temperature dielectric properties with increased doping indicates these nanostructures as viable candidates in energy storage applications. The improvements in ac-conductivity, impedance and modulus spectrum of doped nanostructures are observed. Specific capacitance of 36.22 F/g for Bi0.92La0.08Fe1O3 at 10 mV/s and 21.48F/g for the Bi0.92La0.08Fe0.9Se0.1O3 sample was observed. Weak ferromagnetism is observed in M-H loops with increased Se concentration that also finds applications in magnetic storage devices.

Comparative studies by X-ray diffraction, Raman, vibrating sample magnetometer and Mössbauer spectroscopy of pure, Sr doped and Sr, Co co-doped BiFeO3 ceramic synthesized via tartaric acid-assisted technique

Pure BiFeO3 (BFO), Sr-doped Bi0.97Sr0.03FeO3 (BSFO) and Sr, Co co-doped Bi0.97Sr0.03Fe0.8Co0.2O3 (BSFCO) samples have been prepared via a tartaric acid-assisted sol-gel technique. Investigation of the structure, lattice dynamics, magnetization and hyperfine interaction have been performed through X–ray diffraction (XRD), transmission electron microscope (TEM), Raman spectroscopy (RS), vibrating sample magnetometer (VSM) and Mössbauer spectroscopy (MS). The TEM images show that the particle sizes <D> of BFO, BSFO and BSFCO are respectively 11.4, 12.1 and 8.8 nm. The XRD analysis reflects a structural phase transition from rhombohedral R3c structure in case of BFO and BSFO samples to two phase coexistence (rhombohedral R3c and trigonal R–3m:R) in case of BSFCO sample. This structural phase transition has been strongly confirmed by the alterations in the vibration modes observed in Raman spectra (expansion, shift, merge, and reduced intensity). Second order vibration modes, corresponding to the two-phonon scattering in the range 650–1000 cm−1, have been recorded for all samples. Investigation of magnetic properties reveals that pure and Sr doped samples possess considerably high magnetic saturations (Ms = 5.61 and 5.79 emu/g respectively). Additionally, BSFCO sample shows enhancement in Ms (Ms rises to 8.26 emu/g). Suppression of spiral spin structure caused by the small nano-size has been assumed. The destruction of the spiral spin has been also suggested through M össbauer studies. The hyperfine parameters reveal that only Fe3+ is observed in two different nonequivalent trigonal distorted octahedral environments. The outcome of this work suggests the potentiality of Sr, Co co-doping to improve the structure and ferromagnetism of BiFeO3 ceramic making it feasible to be employed in enormous applications.

Zn-Y co-doped LiNi0.5Mn1.5O4 cathode materials with high electrochemical performance

The LiNi0.5−xZnxMn1.48Y0.02O4 (x = 0.01, 0.03, 0.05) series were prepared via a sol-gel method. The mechanism of the Zn2+ and Y3+ co-doping on the structural morphology and Mn3+ ion dissolution, which led to the improved electrochemical performance of the LiNi0.5Mn1.5O4 (LNMO) sample, were studied. Compared with the pristine LNMO, Zn-Y co-doping led to increased lattice parameters, morphological evolution, decreased Mn3+ content, and better electrochemical properties. Among all the samples, LiNi0.47Zn0.03Mn1.48Y0.02O4 (0.03ZnY) showed optimal electrochemical properties at room temperature and elevated temperature. After 200 cycles, the 0.03ZnY sample showed excellent cycling performance, i.e., 134.529 mAh g−1 at 1 C (with a capacity retention of 94.7%), which was higher than the pristine sample (104.913 mAh g−1, with a capacity retention of 92.7%). Furthermore, when tested at 1 C, at a high temperature (55 °C), the 2.03Zn-Y sample reached a discharge capacity of 94.004 mAh g−1 and maintained a 79.6% capacity retention after 120 cycles, which was higher than the pristine sample (52.430 mAh g−1, 43.6% capacity retention).

The MIL100(Fe)/BaTi0.85Zr0.15O3 nanocomposite with the photocatalytic capability for study of tetracycline photodegradation kinetics

The visible light-active nanocomposite with the photocatalytic capability was facile one-pot solvothermal method successfully synthesized. X-ray diffraction (XRD), Thermogravimetry and Derivative Thermogravimetry (TG-DTG), Scanning Electron Microscopy with Energy Dispersive X-ray Analysis (SEM-EDX), Diffuse Reflectance Spectroscopy (UV–Vis DRS), and Fourier Transform Infra-Red (FT-IR) analysis were employed to characterize the synthetized BaTi0.85Zr0.15O3, MIL-100(Fe), and the MIL-100(Fe)/BaTi0.85Zr0.15O3 samples. As a result of the Scherrer equations, the size of grains for MIL-100(Fe), BaTi0.85Zr0.15O3, and MIL-100(Fe)/BaTi0.85Zr0.15O3 was estimated to be 40.81, 12.00, and 22.70 nm, respectively. MIL-100(Fe), BaTi0.85Zr0.15O3, and MIL-100(Fe)/BaTi0.85Zr0.15O3 samples showed bandgap values of 1.77, 3.02, and 2.56 determined from their absorption edge wavelengths. In the photodegraded solutions, chemical oxygen demand (COD) data and tetracycline (TC) absorbencies were used to obtain the rate constants of 0.032 min−1 and 0.030 min−1, respectively. This corresponds to t1/2-values of 27.7 min and 21.7 min, respectively, for the degradation and mineralization of TC molecules during photodegradation process.

Effect of Fe3+ and/or PO43– Doping on the Electrochemical Performance of LiNi0.5Mn1.5O4 Cathode Material for Li-Ion Batteries

An Fe3+/PO43– codoped LiNi0.5Mn1.4667Fe0.02P0.0133O4 sample has been prepared by a coprecipitation–hydrothermal method followed by two-step calcination. A novel wet chemical route, using FeSO4 rather than Fe2(SO4)3 as the Fe3+ source and NaH2PO4 as the PO43– source, is adopted to obtain uniform codoping of Fe3+ and PO43– ions in a carbonate precursor according to the precipitation–dissolution–transformation mechanism. For comparison, Fe3+-doped and PO43–-doped samples have been also synthesized via the same route. The effects of Fe3+/PO43– codoping and single doping on the crystalline structure, morphology, and electrochemical performance of LiNi0.5Mn1.5O4 are investigated. Compared with pristine and single doped samples, the codoped sample shows better electrochemical performance, with a specific discharge capacity of 125.2 mAh g–1 at 10 C and a capacity retention rate of 85.9% after 200 cycles at 1 C, under the synergy of Fe3+/PO43– codoping, including enhanced crystallinity, decreased Mn3+ content, significantly reduced primary particle size and secondary agglomeration, as well as the appearance of (110) surfaces in truncated octahedral primary particles.

Синтез и каталитическая активность высокодисперсных твердых растворов Ce0,9Sn0,1O2 и Ce0,8Sn0,1Zr0,1O2 в реакции окисления СО

Fluorite-like solid solutions of Ce0.9Sn0.1O2 and Ce0.8Sn0.1Zr0.1O2 are synthesized by co-precipitation using ammonium carbonate as a precipitant. The samples were characterized by X-ray phase analysis, electron microscopy, energy dispersive analysis, low-temperature nitrogen adsorption, and gas chromatography. It is shown that the formation of solid solutions occurs even at an annealing temperature of 550°C. In this case, the formation of lamellar particles occurs, the size of which, according to SEM data, is 4 μm. The synthesized materials have a mesoporous structure. The specific surface area of Ce0.9Sn0.1O2 samples is 80.6 m2/g, Ce0.8Zr0.1Sn0.1O2 is 76.3 m2/g. Carrying out the calcination at a temperature of 800 °C leads to an increase in the particle size up to 8 – 10 µm. The highest specific surface area of 15.3 m2/g is typical for the Ce0.8Zr0.1Sn0.1O2 sample, which is due to the presence of zirconium ions in its composition. The synthesized compositions demonstrated high activity in CO oxidation. The maximum catalytic activity was observed for the bicomponent system Ce0.9Sn0.1O2: T50% — 180°C, T90% — 236 °C. For samples calcined at a temperature of 800 °C, the most active is Ce0.8Zr0.1Sn0.1O2, which is due to the formation of a more thermally stable system compared to cerium dioxide and Ce0.9Sn0.1O2. To increase the thermal stability, it is advisable to dope the bicomponent composition Ce0.9Sn0.1O2 with Zr+4 ions.

Synthesis of Microsheets Bi4Ti3O12 and Bi4Ti2.95V0.05O12 via Molten NaCl-KCl Salt Method

Bi4Ti3O12 is a tri-layer Aurivillius member compound that was reported to have good photocatalytic properties. Metal element doping and morphological particle tuning are strategies to increase photocatalyst activity. In this research, the compound micro sheets Bi4Ti3O12 and Bi4Ti2.95V0.05O12 were synthesized using molten NaCl/KCl salt. The diffractogram shows that the Bi4Ti3O12 sample was successfully synthesized, however, there are still found impurities at the Bi4Ti2.95V0.05O12 sample. Micrographs showed that the morphology particle samples is. The results of UV-Vis DRS spectra calculation show that both samples have a band gap energy of ~2.97 eV.

High-temperature mass spectrometric study and modeling of ceramics based on the Al2 O3 -SiO2 -ZrO2 system.

Materials based on the Al2 O3 -SiO2 -ZrO2 system are promising for a wide range of high-temperature technological applications, such as thermal barrier coatings in the aviation and space industry or advanced materials in nuclear power reactors. Experimental studies of the ceramics based on this system by the Knudsen effusion mass spectrometric (KEMS) method are of significant interest in designing technological processes for the synthesis and exploitation of the Al2 O3 -SiO2 -ZrO2 materials. Samples of ceramics in the Al2 O3 -SiO2 -ZrO2 system, including the Al2 O3 -ZrO2 and SiO2 -ZrO2 binaries, were prepared by solid-state synthesis. Analysis of the samples was performed by X-ray fluorescence and diffraction techniques. The vapor composition and thermodynamic properties of the components in this system were determined by KEMS. The derived thermodynamic functions were optimized within the generalized lattice theory of associated solutions (GLTAS). In the temperature range 1900-2600 K, the SiO, Al,AlO, Al2 O, ZrO, ZrO2 , and O vapor species were identified over the samples in the systems under study. For the thermodynamic properties to be determined correctly, the samples of the Al2 O3 -SiO2 -ZrO2 system had to be vaporized at temperatures less than 2000 K, where data could be obtained only for the SiO species. The SiO2 activities obtained were taken as the experimental basis for the modeling within the GLTAS approach. This allowed evaluation of the component activities and excess Gibbs energy, and assessment of the relative number of bonds of different types. At 1920 K, the Al2 O3 -SiO2 -ZrO2 system is characterized by negative deviations of its thermodynamic properties from the ideal behavior. The consistency of the obtained modeling results was illustrated by comparison of the values derived from the data for the ternary and the boundary binary systems and thereby indicates the reasonable uniformity of the energy parameters of the lattice model derived in the calculations, which may be used in further modeling of multicomponent systems.

High relative permittivity and excellent dye photo-elimination: Pure and (Zr4+, Y3+, Sb5+) multi-doped anatase TiO2 structure

Herein, multifunctional characteristics including solar photocatalytic, dielectric constant and ac electrical conductivity have been studied for pure and Zr4+, Y3+ and Sb5+ multidoped TiO2 n-type semiconductor. Pure, Zr doped, (Zr, Y) codoped and (Zr, Y, Sb) tridoped TiO2 with chemical compositions of TiO2, Ti0.98Zr0.02O2, Ti0.96Zr0.02Y0.02O2 and Ti0.94Zr0.02Y0.02Sb0.02O2 were prepared via a low cost coprecipitation technique. All compositions reveal a pure single phase of anatase TiO2 structure with different unit cell volume due to the differences in ionic radii between parent cation (Ti4+ = 0.605 Å) and dopants ions (Zr4+ = 0.72 Å), (Y3+ = 0.9 Å) and (Sb5+ = 0.6 Å). Morphological changes for TiO2 particles were seen due to incorporation of Zr4+, Y3+ or Sb5+ cations into TiO2 lattice. Optically, Zr4+, Y3+ and Sb5+ ions cause a red shift for the absorption edge and reduce the width of the bang gap energy of TiO2 as well as enhance its refractive index value. High dielectric constant of 2214 (42 Hz) was detected for Ti0.94Zr0.02Y0.02Sb0.02O2 composition. Ti0.94Zr0.02Y0.02Sb0.02O2 sample reveals the highest ac electrical conductivity (σac) values compared to undoped TiO2, Ti0.98Zr0.02O2 and Ti0.96Zr0.02Y0.02O2 samples. High efficiency (∼100%) and fast (20–40 min) solar photodegradation characteristics for 10 ppm Congo red (CR) was realized via TiO2 and Ti0.96Zr0.02Y0.02O2 catalysts. For 40 ppm CR, pure TiO2 exhibits a high photocatalytic activity of 80% after 120 min of sunlight irradiation. Interestingly, this study also illustrates that the starting materials (titanium butoxide-butanol solvent) used in the synthesis process play a significant role in the phase structure as well as the ultimate photocatalytic properties of TiO2 based compositions.