Nm For Samples Research Articles

Enhanced random vector functional link based on artificial protozoa optimizer to predict wear characteristics of Cu-ZrO2 nanocomposites

Owing to the absence of scientific methods for predicting nanocomposites' wear rates, a freshly updated machine learning method that uses an Artificial Protozoa Optimizer (APO) to forecast the tribological performance of Cu-ZrO2 nanocomposites was proposed. The updated model was used to predict the coefficients of friction and wear rates of Cu-ZrO2 nanocomposites produced in this work. Copper-zirconia nanocomposite powders were fabricated utilizing the ball milling process, varying in milling time and ZrO2 weight percentage. The effect of reinforcement percentage and milling time on the morphology and microstructure of the copper composite powders was characterized. The study concentrated on the effects of high-energy ball milling on the morphology, microstructure, and microhardness of the resulting composites. After cold compaction at 700 MPa of pressure, the resultant powders were sintered for 2 h at 950 °C in a hydrogen atmosphere. Based on the results, a 20-h milling time is the best option for creating a Cu-ZrO2 nanocomposite with evenly distributed reinforcement. The microhardness and wear rate of the Cu-15%ZrO2 nanocomposites are improved by 66.2 %, and 81.1 %, respectively, when compared to pure copper. The crystallite size decreases significantly with the addition of ZrO2, reaching 32.5 and 11.1 nm for samples containing 5 and 15 % weight percent ZrO2. That is why there is a rise in wear and mechanical properties. For Cu-ZrO2 nanocomposites with reinforcement content up to 15 %, the model constructed using the APO method demonstrated excellent forecasting of the wear rate and coefficient of friction.

Magnetic Domain and Structural Defects Size in Ultrathin Films

Herein, a model is proposed for measuring the structural defects size r0 in an ultrathin magnetic layer with perpendicular magnetic anisotropy. Based on the observations of magnetic domains in Ta/Pt/Co/Pt ultrathin films, using polar magneto‐optical Kerr effect microscopy and measurements of their magnetic anisotropies, the correlation between magnetic domains size D and structural defects size r0, as well as the defects concentration parameter αK, which designates the degree of pinning, has been modeled. The average r0 value found is high in the sample with unannealed buffer layers and considerably decreases with annealing. It is 6.17 nm with unannealed Ta/Pt buffer layers, 1.06 nm in sample with Ta/Pt buffer layers annealed at 423 K, and 0.49 nm in that with buffer layers annealed at 573 K. The significant drop of r0 is in good agreement with the high depinning noted with buffer layers annealing in recent work.

Characterization of Fe-Cr alloys irradiated by neutrons at intermediate temperature

A series of Fe-Cr alloys, with 3 at.% - 18 at.% Cr, was irradiated in the Advanced Test Reactor (ATR) at the Idaho National Labs (INL), USA, up to a dose of ∼6.7 dpa at a temperature of ∼456 °C. Transmission electron microscopy (TEM) samples were extracted using a focused ion beam (FIB) instrument, and the resulting microstructural defects, such as voids, dislocation loops, network dislocations, Cr rich precipitates, etc., were characterized using a TEM. It was found that the size and number density of these defects varied widely over the different alloys with varying Cr content. As expected, there were no Cr rich precipitates in samples with Cr up to 9 %, and they started appearing only in samples with 12 at.% Cr and above. The particle size decreased from about 15 nm at 12 % Cr to 8 nm at 18 % Cr, while the number density increased from ∼7e20 /m3 to 6e22 /m3 for the same Cr contents. Grain boundary segregation of Cr, along with a precipitate free zone, was observed in the cases where a boundary was present in the sample. Large voids (>1–2 nm) were almost invisible in the Fe-3at.%Cr sample, while the average void size remained almost constant between 15 and 18 nm for samples with 6–15 at.% Cr and increased slightly at 18 at.% Cr to ∼22 nm. Fe-3 %Cr showed a high density of small voids(<2 nm), estimated to be about 1e23/m3. The number density of large voids increased from ∼0 at 3 % Cr to a peak of ∼6.4e20 /m3 at 12 % Cr, then decreased to about 1.1e20 /m3 at 18 % Cr. The dislocation loops, which appeared in linear arrays in the Fe-9 %Cr sample, were analysed in detail using both invisibility criteria and image simulations using the Oxford University TEMACI software, and it was found that they are most likely to be ½ 〈111〉 type loops on {100} planes. These loops seem shaped like sections of helices in some places and are most likely formed by loops near screw dislocations climbing into a helix and then collapsing into a loop array. Similar dislocation analysis was performed in the other samples as well wherever feasible, and it was found that there is a mixture of ½ 〈111〉 and [100] dislocation loops.

Improved magnetic, electrical, and dielectric characteristics of graphene nano-platelets (GNPs)-Integrated Ni0·4Cd0·6Fe1.97Sm0.03O4 ferrite composites synthesized via sol-gel auto-combustion method

This research work analyzes the impact of graphene nanoplatelets (GNPs) on the structural, electrical, dielectric, optical, and magnetic properties of the Ni0·4Cd0·6Fe1.97Sm0.03O4/x-GNPs (SNCF/GNPs) composites (x = 0 %, 2.5 %, and 5 %) prepared via the sol-gel auto-combustion route. The results revealed that SNCF particles were distributed on GNPs which improved the multifaceted properties of SNCF spinel ferrites. XRD analysis confirmed the FCC spinel structure with a minimum crystallite size (D) of 18.99 nm for sample with 5 wt %GNPs. The DC electrical resistivity decreased from 9.06 × 1011 Ω-cm at 313K to 1.41 × 108 Ω-cm at 673K, revealing the semi-conducting nature of composites. The improved electroconductivity and reduced bandgap energy are observed for samples with minimum resistivity 1.02 × 105 Ω-cm at 673K and 1.70 eV energy, respectively, containing 5 wt %GNPs. Samples show higher permittivity values at low frequency and decreased at high frequency. The maximum ac conductivity is observed for composite with 5 wt %GNPs which is attributed to the hopping mechanism. Finally, the magnetization (Ms) increased from 52.24 to 79.71 emu/g with increasing GNPs contents. Hence, the synthesized composites with 5 wt %GNPs are more favorable than the pure sample for application in waste-water treatment, high-frequency devices, and energy storage devices.

THE DESIGN AND CHARACTERIZATION OF MODIFIED POLYTHIOPHENE SUPPORTED PLANT MEDIATED CO-NI BIMETALLIC NANOCOMPOSITES

Ficus mucuso leaf extract was employed as reducing agent in the synthesis of Co-Ni bimetallic nanoparticles (BMNPs) with two precursors namely; Cobalt (ii) nitrate hexahydrate; [CO(NO3)2.6H2O] and nickel (ii) nitrate hexahydrate; [Ni (NO3)2.6H2O]. Afterwards, acid modified polythiophene was synthesized through the in-situ and ex-situ coupling approach. The nanocomposite obtained from the in-situ method was labelled ‘A’ and that of the ex-situ, ‘B’. The in-situ approach was considered to be more appropriate for synthesizing the BMNPs as confirmed by characterization using Fourier Transform Infrared Spectroscopy (FTIR), X-Ray diffraction analysis (XRD), Energy dispersive X-ray (EDX) analysis, Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and Scanning electron microscopy (SEM) techniques. The hexagonal cobalt and the cubic nickel were investigated using XRD to determine the particle sizes taking Debye-Scherrer’s equation to be around 14.495nm for sample A and 15.689nm for sample B. This was reported to be responsible for the corresponding intense peak at A over B. The SEM and TEM measurements portray good correlation indicating the presence of agglomerates in sample B. The EDS analysis taken reported a higher weight of the cobalt and nickel compositions in A than in B. TGA explained the higher decomposition rate of B than A. Also, a more pronounced intense peak was observed in A than in B using FTIR technique. This comparison of both samples makes in-situ synthesis unquestionably the best because of its outstanding performance over ex-situ approach. This is the first report of Ficus Mucuso plant extract being used in nanosynthesis.

Fundamental Origin of Si Surface Defects Caused by Laser Irradiation and Prevention of Suboxide Formation through High Density Ultrathin SiO2

This research investigates surface damage in electronic devices from laser irradiation, particularly focusing on voids, cracks, and vacancies. We discovered that applying a high-density ultrathin SiO2 layer effectively prevents such defects. Atomic Force Microscopy (AFM) analysis showed a significant reduction in surface roughness, with the Rq factor value dropping to 0.158 nm in samples coated with this SiO2 layer. Additionally, X-ray Photoelectron Spectroscopy (XPS) was used to study suboxide formation in the Al2O3/Si structure, revealing insights into defect origins. Electrical tests indicated a substantial decrease in laser-induced damage, evidenced by a leakage current density reduction to 2.4 × 10−6 A/cm2, markedly lower than uncoated samples. Post-metallization annealing (PMA) further improved results, with the interface state density decreasing to 0.63 × 1012 atoms eV−1 cm−2. Our findings highlight the effectiveness of the high-density ultrathin SiO2 layer in mitigating surface defects caused by continuous wave (CW) laser irradiation, promising significant advancements in electronic device manufacturing through potential application in CW laser annealing processes.

Engineering electrically tunable TiN/SiO2 epsilon-near-zero metamaterials

Electrically tunable TiN/SiO2/TiN epsilon-near-zero photonic structures with various parameters were fabricated using the reactive DC magnetron sputtering approach. Effective medium approximation was used to predict the optical permittivity of a multilayered TiN/SiO2 metamaterial and guide the design/fabrication. Experimental reflectance measurements for tunable TiN/SiO2/TiN structures were obtained using the ellipsometer technique in the visible and near-infrared spectral ranges. Results show that reflectance for biased (12 V) and un-biased bulk TiN/SiO2/TiN structure changes up to ∼ 2% with the spectral shift at the ENZ spectral point ∼ 10 nm for samples with an optimal SiO2 dielectric layer (thickness d=10 nm). Reflectance measurements for multilayered tunable TiN/SiO2/TiN structures show strong variation in reflectance change for s- polarized light at epsilon-near-zero wavelengths due to applied voltage (12 V). We expect that the results of this research study of the tunable TiN/SiO2/TiN epsilon-near-zero photonic structures will potentially be useful for the photonic density of states engineering, surface sensing, and metamaterial-based super-resolution imaging.

Non-stoichiometric silicon nitride for future gravitational wave detectors

Silicon nitride thin films were deposited at room temperature employing a custom ion beam deposition (IBD) system. The stoichiometry of these films was tuned by controlling the nitrogen gas flow through the ion source and a process gas ring. A correlation is established between the process parameters, such as ion beam voltage and ion current, and the optical and mechanical properties of the films based on post-deposition heat treatment. The results show that with increasing heat treatment temperature, the mechanical loss of these materials as well as their optical absorption decreases producing films with an extinction coefficient as low as k=6.2(±0.5)×10−7 at 1064 nm for samples annealed at 900 ∘C. This presents the lowest value for IBD SiN x within the context of gravitational wave detector applications. The mechanical loss of the films was measured to be ϕ=2.1(±0.6)×10−4 once annealed post deposition to 900 ∘C.

Твердофазный синтез нанокристаллического гафната иттрия с применением механоактивации

The processes occurring during the synthesis of yttrium hafnate Y2Hf2O7 by solid-phase method using mechanical activation were studied. Mechanoactivation of stoichiometric mixture of yttrium and hafnium oxides was carried out in a laboratory planetary mill AGO-2 at a centrifugal factor of 40 g for 10 min. According to infrared spectroscopy data the processes of hydration and carbonization of samples during mechanical activation due to the absorption of moisture and air carbon dioxide were established. The temperature of dehydration and decarbonization during heat treatment of mechanoactivated oxide mixture was determined. X-ray phase analysis showed that the calcination of mechanoactivated oxide mixture produced Y2Hf2O7 with fluorite structure. The sizes of yttrium hafnate crystallites were calculated using the Scherrer method and were 22 and 94 nm for samples calcined at 1100 and 1200 °C for 3 h, respectively.

Preparation of LiNbO3 nanoparticles by green synthesis laser ablation in water

The use of LiNbO3 nanoparticles in nonlinear applications is attractive and promising. The particle size and morphology of LiNbO3 are the key parameters affecting their application. In this study, spherical nanoparticles of lithium niobate were synthesised by nanosecond Nd:YAG laser ablation in water. The polycrystalline, rhombohedral structure of the synthesised LiNbO3 nanoparticles with x-ray diffraction experiments was verified. The bandgap energy of colloidal LiNbO3 nanoparticles varied between 4.25 and 4.9 eV based on the laser fluence, according to the optical characteristics. The photoluminescence (PL) reveals that the emission peaks are centered at 293, 300, 305, and 309 nm for samples prepared at 1.3, 1.6, 2.0, and 2.2 J cm−2/pulse, respectively. The transmission electron microscope investigation confirmed the formation of spherical nanoparticles with an average size ranging from 18 to 34 nm. Raman studies on nanoparticles synthesised at various laser fluences are being conducted.

Nanocomposites Based on Polyethylene and Nickel Ferrite: Preparation, Characterization, and Properties.

Composite materials based on NiFe2O4 nanoparticles and polyethylene matrix have been synthesized by thermal decomposition to expand the application area of high-pressure polyethylene by filling it with nanoscale particles. The synthesized compositions were obtained in the form of a dark gray powder and compressed for further study According to TEM, the average particle size in composites was 2, 3, and 4 nm in samples with a filling of 10%, 20% and 30%. The concentration dependences of the specific electrical resistivity ρV, dielectric permittivity ε, saturation magnetization MS and the parameters of reflection and attenuation of microwave power of the obtained composites were investigated. The threshold for percolation in such materials is found to be within a concentration range of 20…30%. The electronic and atomic structure of composites was studied by methods of Mössbauer spectroscopy, X-ray diffraction and X-ray absorption spectroscopy. The closest atomic environment of nickel and iron in nanoparticles is close to that of crystalline NiFe2O4. The dependence of the nanoparticles size as well as the dependence of the number of tetrahedral or octahedral iron positions in nickel ferrite nanoparticles to their content in polyethylene matrix is established. It is shown that composite materials based on NiFe2O4 nanoparticles and polyethylene matrix can be used as components of electromagnetic compatibility systems.

Nondestructive identification of soybean protein in minced chicken meat based on hyperspectral imaging and VGG16-SVM

A rapid and nondestructive method for identification of soybean protein in minced chicken meat based on visible-near infrared hyperspectral imaging (HSI) technology and VGG16-SVM model was proposed in this study. The hyperspectral data from 400.89 nm to 1000.19 nm of samples with different soybean protein contents were collected. Spectral data was transformed into spectrograms through Continuous wavelet transform (CWT). Comparing with other methods, the optimum data preprocessing results were obtained for the subsequent research. Then, VGG16-SVM model based on VGG16 network in which fully connected layer was replaced by support vector machine (SVM) was established to identify soybean protein in minced chicken meat. The results showed that VGG16-SVM model with radial basis function (RBF) as kernel function performed best and the classification accuracy reached 98.1%. Meanwhile, the proposed model was superior to the SVM, convolution neural network (CNN) and VGG16 model. It is feasible and effective for combining HSI technology and VGG16-SVM to realize nondestructive identification of soybean protein in minced chicken meat.

Study of The Structural, Optical, and Morphological Properties of Sno2 Nanofilms under the Influence of Gamma Rays

This study reports the fabrication of tin oxide (SnO2) thin films using pulsed laser deposition (PLD). The effect of 60Co (300, 900, and 1200 Gy) gamma radiation on the structural, morphological, and optical features is systematically demonstrated using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and ultraviolet-visible light analysis (UV-Vis), respectively In XRD tests, the size of the crystallites decreased from 45.5 to 40.8 nm for the control samples and from 1200 Gy to 60Co for the irradiated samples. Using FESEM analysis, the particle diameter revealed a similar trend to that attained using XRD; in particular, the average diameters were 93.8 and 79.9 nm for the samples mentioned above. A similar profile was observed for the AFM analysis in which an increase in the radiation dose from 300 to 1200 Gy resulted in a decrease in the RMS values from 74.6 to 32.25 nm. Contrariwise, the calculated optical band gap demonstrated an increasing profile where optical band gaps of 3.08 and 3.18 eV were acquired for control and samples irradiated with 900 Gy. However, the attained optical band gap was further increased to 3.24 eV due to the 60Co gamma radiation increment to 1200 Gy.

Characteristic Length for Pinning Force Density in Nb3Sn.

The pinning force density, Fp, is one of the main parameters that characterize the resilience of a superconductor to carrying a dissipative-free transport current in an applied magnetic field. Kramer (1973) and Dew-Hughes (1974) proposed a widely used scaling law for this quantity, where one of the parameters is the pinning force density maximum, Fp,max, which represents the maximal performance of a given superconductor in an applied magnetic field at a given temperature. Since the late 1970s to the present, several research groups have reported experimental data on the dependence of Fp,max on the average grain size, d, in Nb3Sn-based conductors. Fp,maxd datasets were analyzed and a scaling law for the dependence Fp,maxd=A×ln1/d+B was proposed. Despite the fact that this scaling law is widely accepted, it has several problems; for instance, according to this law, at T=4.2 K and d≥650 nm, Nb3Sn should lose its superconductivity, which is in striking contrast to experiments. Here, we reanalyzed the full inventory of publicly available Fp,maxd data for Nb3Sn conductors and found that the dependence can be described by the exponential law, in which the characteristic length, δ, varies within a remarkably narrow range of δ=175±13 nm for samples fabricated using different technologies. The interpretation of this result is based on the idea that the in-field supercurrent flows within a thin surface layer (thickness of δ) near grain boundary surfaces (similar to London's law, where the self-field supercurrent flows within a thin surface layer with a thickness of the London penetration depth, λ, and the surface is a superconductor-vacuum surface). An alternative interpretation is that δ represents the characteristic length of the exponential decay flux pinning potential from the dominant defects in Nb3Sn superconductors, which are grain boundaries.

Characterization of Synthetic Polymer Coated with Biopolymer Layer with Natural Orange Peel Extract Aimed for Food Packaging.

This research was aimed to make biolayer coatings enriched with orange peel essential oil (OPEO) on synthetic laminate, oriented poly(ethylene-terephthalate)/polypropylene (PET-O/PP). Coating materials were taken from biobased and renewable waste sources, and the developed formulation was targeted for food packaging. The developed materials were characterized for their barrier (O2, CO2, and water vapour), optical (colour, opacity), surface (inventory of peaks by FTIR), and antimicrobial activity. Furthermore, the overall migration from a base layer (PET-O/PP) in an acetic acid (3% HAc) and ethanol aqueous solution (20% EtOH) were measured. The antimicrobial activity of chitosan (Chi)-coated films was assessed against Escherichia coli. Permeation of the uncoated samples (base layer, PET-O/PP) increased with the temperature increase (from 20 °C to 40 °C and 60 °C). Films with Chi-coatings were a better barrier to gases than the control (PET-O/PP) measured at 20 °C. The addition of 1% (w/v) OPEO to the Chi-coating layer showed a permeance decrease of 67% for CO2 and 48% for O2. The overall migrations from PET-O/PP in 3% HAc and 20% EtOH were 1.8 and 2.3 mg/dm2, respectively. Analysis of spectral bands did not indicate any surface structural changes after exposure to food simulants. Water vapour transmission rate values were increased for Chi-coated samples compared to the control. The total colour difference showed a slight colour change for all coated samples (ΔE > 2). No significant changes in light transmission at 600 nm for samples containing 1% and 2% OLEO were observed. The addition of 4% (w/v) OPEO was not enough to obtain a bacteriostatic effect, so future research is needed.

Raman Spectroscopy for Non-Destructive Detection of Pesticide on Guava Peel

Pesticides are one of the substances that are widely used to protect plants from pests and plant diseases, and their use must be controlled for the public health. Currently, the pesticide contamination is determined by chromatographic, but this technique is destructive and not easy to implement. Therefore, this research is proposed to overcome these problems. Raman scattering technique as a non-destructive testing technique and easy to implement is used in this research. This technique utilizes Raman scattering resulting from laser excitation in a sample. Pesticide detection was carried out by observing the difference in Raman shift wavelength between samples containing pesticides and samples that did not contain pesticides. The experiments were done on guava peels with coated pesticide delthametrin 25 g/l. By excitation with laser wavelengths 532 nm and 785 nm, the differences in Raman shifts at wavelengths 1,225 nm and 1,480 for samples coated pesticide, and Raman shifts at wavelengths 1,008 nm and 1,480 nm for samples which is treated are obtained, respectively. From this research, it can be concluded that Raman scattering technique can be used as non-destructive and easy technique for detection pesticide contamination.

The influence of γ-irradiation on molecular structure and mass attenuation coefficients of γ-Al2O3 nanoparticles

In this research, γ-Al2O3 nanoparticles (NPs) were synthesized by using the sol–gel process. The photon attenuation properties of these NPs were obtained by measuring the linear and mass attenuation coefficients (μl, μm) at different photon energies. In addition, the theoretical values of μm for γ-Al2O3 micro-particles were calculated using the WinXCom computer program and compared with the experimental values of μm for NPs of γ-Al2O3. Furthermore, in order to evaluate the impact of γ-irradiation on these NPs, the experimental values of μl and μm for γ-Al2O3 NPs, before and after receiving 20 kGy dose of γ-irradiation, were investigated. It was observed that μm of γ-Al2O3 NPs decreases after receiving γ-irradiation because of increasing the photon’s energy, which indicates the changes in the molecular structure of NPs after γ-irradiation. Moreover, the structural properties of NPs were evaluated by UV–Vis spectroscopy, x-ray diffraction patterns, and scanning electron microscopy images. UV–Vis spectroscopy showed an absorption peak at 212.5 nm before γ-irradiation, and the absorption peak of NPs disappeared when γ-irradiation was started. The average crystalline size was determined to be 3.65 nm in the sample before γ-irradiation and 9.29 nm in the sample with the maximum dose of 20 kGy. The results of scanning electron microscopy show an increase in particle size from 6.5 nm in a non-irradiated sample up to 9 nm in a sample with the highest γ-irradiation dose.

Tuning structural, electrical, dielectric and magnetic properties of Mg–Cu–Co ferrites via dysprosium (Dy3+) doping

In current research work, Dy3+ substituted Mg0.5Cu0.25Co0.25Fe2‒xDyxO4 (0.0 ≤ x ≤ 0.04 with the step interval of 0.01) soft ferrites were synthesized by the sol–gel auto combustion method. The prepared samples were characterized by the techniques using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, current–voltage (I–V) measurement, LCR meter, vibrating sample magnetometer (VSM) and Raman. XRD data reveal that the average crystallite size is 49.71 nm and the lattice constant is 0.83703 nm for sample x = 0.03. The non-uniform grain growth was demonstrated by micrographs and impurity-free elemental composition was observed from EDX analysis. The DC resistivity has an increasing and decreasing trend in ferromagnetic and paramagnetic regions with an increase in temperature. Moreover, the high resistivity is observed with the order of 1010 Ω·cm, and the activation energy is 0.944 eV for samples x = 0.03. The dielectric parameters including dielectric constant, dielectric losses, and impedance gradually decrease with the increase in frequency from 8 Hz to 8 MHz. The minimum dielectric loss at high frequency is found for sample x = 0.03. The coercivity (Hc) and saturation magnetization (Ms) are found in the ranges of 520.82–544.02 Oe and 20.5841–21.1473 emu/g, respectively. These observations confirm that dysprosium (x = 0.03) doped MCC-soft ferrites may be applicable in transformer cores, microwave absorbance, and telecommunication devices.

Investigation of photocatalytic and luminescence properties of Na0.5Ce0.5WO4 self-assembled photocatalysts under solar light irradiation: Morphological, temperature and pH role

Tungstate-based scheelite structures have attracted much attention for the photocatalytic, adsorption and luminescence. To improve their performance, several ways have been considered, such as morphology control, thermal treatment and nanostructuring materials. In this work, three uniform and homogeneous morphologies, such as spindles, spheres and flowers, of self-assembled three-dimensional Na0.5Ce0.5WO4 were used as photocatalysts for methylene blue dye photodegradation under solar irradiation. Depending on morphology, they required different temperatures to reach crystallization. Thermal treatments at 500 °C and 800 °C resulted in changes in crystallite size, porosity, surface state, but also in bandgap and emission properties. Thus, the crystallite sizes are about 50 nm for samples (spindles and flowers) treated at 500°Cand 87–167 nm for those treated at 800 °C. Their respective bandgap values measured by diffuse reflectance were 2.85 eV beyond 3.15 eV. The samples treated at 500 °C showed a lower emission and a longer charge carrier lifetime. A strong trend to adsorption was revealed, especially at low pH value and for the samples treated at 500 °C, reaching 100% at a pH value of 2.5. With decreasing pH, the photocatalysis activity increases (up to 50%), being also more efficient with catalysts treated at low temperature. It follows that the degradation efficiency of spindles treated at 500 °C is clearly higher compared to other morphologies treated at different temperature, and suitable for solar photocatalysis.

Quantum effects in silicon-germanium p-type heterostructures with quantum wells of different widths

The magneto-quantum and quantum interference effects in a two-dimensional gas of p-type charge carriers are studied for three quantum wells made of practically pure germanium in a Si0.6Ge0.4/Si0.2Ge0.8/Si0.6Ge0.4 heterostructure. The quantum well widths were 8 nm for sample I, 19.5 nm for sample II, and 25.6 nm for sample III. The dependences of resistance on the magnetic field for all samples exhibit Shubnikov–de Haas oscillations. Their analysis made it possible to calculate the kinetic characteristics of charge carriers for the cases of one (sample I) and two occupied subbands (samples II and III). In the region of weak magnetic fields (B &amp;lt; 0.1 T), the effect of weak localization of holes was revealed, which determines the negative magnetoresistance and the increase in resistance with decreasing temperature. The manifestation of the charge carriers interaction effect at various temperatures and magnetic fields is discovered and analyzed. A transition from the diffusion mode of manifestation of the quantum correction to the intermediate, and then to the ballistic mode is observed. In all regions, the behavior of the quantum correction due to the charge carriers interaction effect is in good agreement with modern theoretical predictions. The temperature dependences of the hole-phonon relaxation time are calculated. In weak magnetic fields, with an increase in the temperature of the 2D system, a transition from the “partial inelasticity” mode, characterized by the dependence τhph−1∝T2, to the small-angle scattering mode, described by the relation τhph−1∝T5, takes place. In stronger magnetic fields for samples with two occupied subbands, the dependence τhph−1∝T3was observed. Possible explanations for this dependence are presented.