Explore the vast range of titles available.

This article is devoted to the study of the effect of ion sputtering on the alloy surface, using the example of martensitic stainless steel AISI 420 with ultrahigh-dose, high-intensity nitrogen ion implantation on the efficiency of accumulation and transformation of the depth distribution of dopants. Some patterns of change in the depth of ion doping depending on the target temperature in the range from 400 to 650 °C, current density from 55 to 250 mA/cm2, and ion fluence up to 4.5 × 1021 ion/cm2 are studied. It has been experimentally established that a decrease in the ion sputtering coefficient of the surface due to a decrease in the energy of nitrogen ions from 1600 to 350 eV, while maintaining the ion current density, ion irradiation fluence and temperature mode of target irradiation increases the ion-doped layer depth by more than three times from 25 μm to 65 µm. The efficient diffusion coefficient at an ion doping depth of 65 μm is many times greater than the data obtained when stainless steel is nitrided with an ion flux with a current density of about 2 mA/cm2.

Regarding aqueous lithium-ion batteries, LiTi 2 (PO 4 ) 3 (LTP) emerges as a promising candidate, distinguished by its substantial specific capacity and structural integrity. While the conventional precipitation methods predominantly employ Ti(C 4 H 9 O) 4 as the titanium source, its inherent deficiencies of hydrolysis, compromised storage stability, and considerable cost have significantly impeded widespread application. In order to solve these problems, this paper introduced Ti(SO 4 ) 2 , a chemically stable inorganic material and crucial industrial intermediate in TiO 2 synthesis, as an economically viable and easily accessible source. Through the development of a novel inorganic precipitation method, this study obtained a homogeneous precursor by in-situ coating LiTi 2 (PO 4 ) 3 anode with tannic acid and in-situ doping. The incorporation of Sn(C 4 H 9 ) 4 through in-situ doping effectively addresses the intrinsic electronic conductivity constraints, with the successful integration of Sn conclusively demonstrated through XPS depth profiling analyses. The resultant Sn-doped LiTi 2 (PO 4 ) 3 /C exhibits refined particle size and enhanced electrochemical characteristics, showing excellent multiplicative cycle stability with a capacity retention of about 75.4% over 1000 cycles. Additionally, the investigation with density flooding theory facilitated the construction of an independent gradient model, indicating the role of Sn doping in enhancing the structural stability of LTP. The electronically constructed model significantly reduces the band gap to improve the electronic conductivity, providing a theoretical basis and some commercial prospects for the new aqueous lithium-ion battery anode.

Gas cluster ion beams (GCIB) have been tuned to enhance secondary ion yields by doping small gas molecules such as CH 4 , CO 2 , and O 2 into an Ar cluster projectile, Ar n   + ( n = 1000–10,000) to form a mixed cluster. The ‘tailored beam’ has the potential to expand the application of secondary ion mass spectrometry for two- and three-dimensional molecular specific imaging. Here, we examine the possibility of further enhancing the ionization by doping HCl into the Ar cluster. Water deposited on the target surface facilitates the dissociation of HCl. This concerted effect, occurring only at the impact site of the cluster, arises since the HCl is chemically induced to ionize to H +  and Cl –  , allowing improved protonation of neutral molecular species. This hypothesis is confirmed by depth profiling through a trehalose thin film exposed to D 2 O vapor, resulting in ~20-fold increase in protonated molecules. The results show that it is possible to dynamically maintain optimum ionization conditions during depth profiling by proper adjustment of the water vapor pressure. H–D exchange in the trehalose molecule M was monitored upon deposition of D 2 O on the target surface, leading to the observation of [M n * + H] +  or [M n * + D] +  ions, where n = 1–8 hydrogen atoms in the trehalose molecule M have been replaced by deuterium. In general, we discuss the role of surface chemistry and dynamic reactive ionization of organic molecules in increasing the secondary ion yield. Graphical Abstract ᅟ

Chemiresistors based on thin films of the Li-doped CuO–TiO2 heterojunctions were synthesized by a 2-step method: (i) repeated ion beam sputtering of the building elements (on the Si substrates and multisensor platforms); and (ii) thermal annealing in flowing air. The structure and composition of the films were analyzed by several methods: Rutherford Backscattering (RBS), Neutron Depth Profiling (NDP), Secondary Ion Mass Spectrometry (SIMS), and Atomic Force Microscopy (AFM), and their sensitivity to gaseous analytes was evaluated using a specific lab-made device operating in a continuous gas flow mode. The obtained results showed that the Li doping significantly increased the sensitivity of the sensors to oxidizing gases, such as NO2, O3, and Cl2, but not to reducing H2. The sensing response of the CuO–TiO2–Li chemiresistors improved with increasing Li content. For the best sensors with about 15% Li atoms, the detection limits were as follows: NO2 → 0.5 ppm, O3 → 10 ppb, and Cl2 → 0.1 ppm. The Li-doped sensors showed excellent sensing performance at a lower operating temperature (200 °C); however, even though their response time was only a few minutes, their recovery was slow (up to a few hours) and incomplete.

We report the rf performance of a single cell superconducting radiofrequency cavity after low temperature baking in a nitrogen environment. A significant increase in quality factor has been observed when the cavity was heat treated in the temperature range of120–160°Cwith a nitrogen partial pressure of∼25mTorr. This increase in quality factor as well as theQ-rise phenomenon (anti-Q-slope) is similar to those previously obtained with high temperature nitrogen doping as well as titanium doping. In this study, a cavityN2-treated at120°Cand at140°Cshowed no degradation in accelerating gradient, however the accelerating gradient was reduced by∼25%with a160°CN2treatment, compared to the baseline tests after electropolishing. Sample coupons treated in the same conditions as the cavity were analyzed by scanning electron microscope, x-ray photoelectron spectroscopy and secondary ion mass spectroscopy revealed a complex surface composition ofNb2O5, NbO andNbN(1−x)Oxwithin the rf penetration depth. Furthermore, magnetization measurements showed no significant change on bulk superconducting properties.

The impact of europium doping on the electronic and structural properties of the topological insulator Bi2Te3 is studied in this paper. The crystallographic structure studied by electron diffraction and transmission microscopy confirms that grown by Molecular Beam Epitaxy (MBE) system film with the Eu content of about 3% has a trigonal structure with relatively large monocrystalline grains. The X-ray photoemission spectroscopy indicates that europium in Bi2Te3 matrix remains divalent and substitutes bismuth in a Bi2Te3 matrix. An exceptional ratio of the photoemission 4d multiplet components in Eu doped film was observed. However, some spatial inhomogeneity at the nanometer scale is revealed. Firstly, local conductivity measurements indicate that the surface conductivity is inhomogeneous and is correlated with a topographic image revealing possible coexistence of conducting surface states with insulating regions. Secondly, Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) depth-profiling also shows partial chemical segregation. Such in-depth inhomogeneity has an impact on the lattice dynamics (phonon lifetime) evaluated by femtosecond spectroscopy. This unprecedented set of experimental investigations provides important insights for optimizing the process of growth of high-quality Eu-doped thin films of a Bi2Te3 topological insulator. Understanding such complex behaviors at the nanoscale level is a necessary step before considering topological insulator thin films as a component of innovative devices.

Within the spin-polaron concept for hole-doped cuprates superconductors the temperature and doping dependence of the London penetration depth λ is studied. To calculate λ we developed a novel approach which (i) does not suppose the analytical expression for the quasiparticle spectrum to be known in advance, and (ii) allows to take into account the strong coupling between a spin localized on the copper ion and a hole residing on the four nearest oxygen ions rigorously. Within this approach the expression for supercurrent density j⃗ is obtained in the long-wavelength limit for external magnetic field vector potential. It is shown that j⃗ is mainly due to the spin-polaron quasiparticles rather then bare oxygen holes. Temperature dependence of λ−2 at various doping is calculated and compared with available experimental data. It is argued that the inflection point revealed experimentally in the temperature behavior of λ−2 in La1.83Sr0.17CuO4 may be considered as a manifestation of the spin-polaron nature of quasiparticles in cuprates.

Very recently, we reported a novel doping method called plasma doping without any external bias (PDWOEB) for the introduction of some impurities into Si and GaN at room temperature (RT). In this work, the RT doping of some impurities, including B, Mg, Ni, Cu, Mn, Cr and Fe, into SiC with ultra-shallow depths of tens of nanometer and very high surface concentrations, approaching or exceeding 1E20/cm 3 , by using PDWOEB is reported. It has been found for the first time that the doping depths and surface concentrations of these impurities doped into SiC by the PDWOEB increase drastically with increasing doping time and the ferromagnetism of SiC due to Ni doping is demonstrated. Moreover, the approximate diffusivities of B, Mg, Ni, Cu, Mn, Cr and Fe in SiC at RT under plasma stimulation are obtained. The physical mechanism of PDWOEB is further discussed, and some unclear viewpoints are clarified.

Cu0.5Tl0.5Ba2Ca3Cu4O12−δ/(Fe–Pd 0, 0.5, 1.0, 1.5 %) superconductors are prepared at normal pressure by using three-step method. Alloy of Cu0.5Tl0.5Ba2Ca3 Cu4O12−δ/(Fe–Pd 1 %) have shown maximum increase in the magnitude of superconductivity. Cu 0.5Tl 0.5 Ba2Ca 3Cu 4O12−δ/(Fe–Pd 0, 0.5, 1.0, 1.5 %) samples have shown Tc(R= 0) around 106, 105.3, 102, and 100 K and the onset of diamagnetism around 113, 110, 102, and 105 K, respectively. A comparison of X-ray diffraction (XRD) scans of Fe–Pd nanoparticles with Cu0.5Tl0.5Ba2Ca3Cu4O12−δ/(Fe–Pd 0.5, 1.0, 1.5 %) superconducting samples have shown that the nanoparticles of Fe–Pd are quite stable in the matrix of Cu0.5Tl0.5Ba2Ca3Cu4O12−δ samples even after repeated firing at 890 ∘C. With increase addition of Fe–Pd nanoparticles, the axes length increases, showing some inclusion of nanoparticle into the unit cell of Cu0.5Tl0.5Ba2Ca3Cu4O12−δ samples from the termination ends of crystal.The inclusion of Fe–Pd in the superconducting Cu0.5Tl0.5Ba2Ca3Cu4O12−δ grains is also evidenced in Fourier transform infrared spectroscopy (FTIR) absorption measurements. The Fe–Pd nanoparticles added in Cu0.5Tl0.5Ba2Ca3Cu4O12−δ samples have been found to decrease the population of inter-grain voids that is found to increase the coherence length along the c-axis and the inter-layer coupling J. The FIC analysis of conductivity data haveshown the Fe–Pd nanoparticles diffusing into the inter-grain sites promoted an increase of penetration depth λp.d and Ginzburg–Landau parameter, κ. Due to the this possible diffusion of the Fe–Pd nanoparticles in the superconducting grains, the Tc(R= 0), Bc0(T), Bc1(T), and Jc(0) values are suppressed in Cu0.5Tl0.5Ba2Ca3Cu4O12−δ samples.

At 1100 °C, the diffusion properties of Ti4+ into congruent LiNbO3 crystals codoped with 0.5 mol% Er2O3 and different MgO concentrations of 0.5, 1.0, and 1.5 mol% have been studied by secondary ion mass spectrometry (SIMS). Three Y-cut and three Z-cut plates with different Mg doping levels were coated with a 60-nm-thick Ti film at first and then annealed at 1100 °C for 28 h in a wet O2 atmosphere. SIMS was used to analyze depth profile characteristics of diffused Ti ions and the constituent elements of the substrate as well. The results show that the diffusion reservoir was exhausted and the Ti metal film was completely diffused. All measured Ti profiles follow a Gaussian function. No Mg out-diffusion accompanied the Ti in-diffusion procedure for all crystals studied. The 1/e diffusion depth is similar to 8.3/10.2, 7.4/8.7, and 6.6/8.2 ± 0.2/0.2 μm/μm for the Y/Z-cut crystal with the Mg doping level of 0.5, 1.0, and 1.5 mol%, respectively, yielding a Ti4+ diffusivity of 0.62/0.93, 0.49/0.67, and 0.39/0.60 ± 0.03/0.03 (μm2/h)/(μm2/h), respectively. The diffusion shows definite anisotropy and a considerable MgO doping level effect. Under the same Mg doping level, the diffusion in a Z-cut crystal is faster. The diffusivity decreases with the increase of the Mg doping level. This effect is qualitatively explained from the viewpoint of the Mg doping effect on concentration of the intrinsic defects in LiNbO3 crystal.