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In this paper, the possibility of retreated lithium slag (RTLS) with a high content of alkali, sulfate and fluoride as a partial replacement for fly ash (FA) to produce autoclaved aerated concrete (AAC) was investigated. The influence of the RTLS dosage on the AAC performance were examined. The composition and microstructure of hydrates as well as the microstructure of the RTLS-FA-based AAC compositions were determined by XRD, FTIR, TG-DSC and SEM. The results illustrated that the incorporation of RTLS changed the crystal structure and the microstructure of the tobermorite. With increased RTLS contents, the morphology of tobermorite was changed, and the grass-like tobermorite gradually transformed into network-like tobermorite. The newly formed tobermorite improved the mechanical performance of the AAC. Compared with the RTLS10, the content of tobermorite in the RTLS30 increased by 8.6%. [ABSTRACT FROM AUTHOR]

Recently, we have demonstrated a method to record the longitudinal phase-space distribution of a pulsed cryogenic buffer gas cooled beam of barium fluoride molecules with high resolution. In this paper, we use this method to determine the influence of various source parameters. Besides the expected dependence on temperature and pressure, the forward velocity of the molecules is strongly correlated with the time they exit the cell, revealing the dynamics of the gas inside the cell. Three observations are particularly noteworthy: (1) The velocity of the barium fluoride molecules increases rapidly as a function of time, reaches a maximum 50–200 µ s after the ablation pulse and then decreases exponentially. We attribute this to the buffer gas being heated up by the plume of hot atoms released from the target by the ablation pulse and subsequently being cooled down via conduction to the cell walls. (2) The time constant associated with the exponentially decreasing temperature increases when the source is used for a longer period of time, which we attribute to the formation of a layer of isolating dust on the walls of the cell. By thoroughly cleaning the cell, the time constant is reset to its initial value. (3) The velocity of the molecules at the trailing end of the molecular pulse depends on the length of the cell. For short cells, the velocity is significantly higher than expected from the sudden freeze model. We attribute this to the target remaining warm over the duration of the molecular pulse giving rise to a temperature gradient within the cell. Our observations will help to optimize the source parameters for producing the most intense molecular beam at the target velocity. [ABSTRACT FROM AUTHOR]

The problem of registration and recognition of thermal (3–15 µm) or ultraviolet (0.15–0.25 µm) objects in their surrounding area (0.8–1.1 µm) is solved by using two-channel two-spectrum optical systems. In order to implement innovative single-channel dual-spectrum emission image detectors, implemented in the image intensifier tube's architecture that make it possible to link the images of a thermal or ultraviolet object to an image of a terrain, it is necessary to develop a unified optical-mechanical system. In this paper, an approach for the development of a unified optical system for single-channel dual-spectrum emission image detectors of the image intensifier tube's architecture is proposed and theoretically studied. The proposed optical system makes it possible to form images of objects emitting in the thermal or ultraviolet range in relation to the image of the surrounding area. The choice of the base material, barium fluoride (BaF2), and geometry is based on a significant dispersion of the refractive index of the lens material. When performing calculations of the optical system, Newton's method and the Python language (SciPy library) were used. The optimal values of the thickness of the lenses and the input window of the image intensifier tube, the distance between them, and the radii of curvature of the lens surfaces are calculated. The calculation results can be used in the practical work on the creation of single-channel dual-spectrum emission receivers for images of the image intensifier tube architecture for the images of thermal and ultraviolet objects in relation to images of their surroundings. [ABSTRACT FROM AUTHOR]

Heavy-atom alkaline earth monofluoride molecules are considered as prospective systems to study spatial parity or spatial parity and time-reversal symmetry violating effects such as the nuclear anapole moment or the electron electric dipole moment. A comprehensive and highly accurate theoretical study of the electronic structure properties and transition energies in such systems can simplify the preparation and interpretation of the experiments. However, almost no attempts to calculate quantum electrodynamics (QED) effects' contribution into characteristics of these neutral heavy-atom molecules have been performed. Recently, we have formulated and implemented such an approach to calculate QED contributions to transition energies of molecules [L. V. Skripnikov, J. Chem. Phys. 154, 201101 (2021)]. In this paper, we perform a benchmark theoretical study of the transition energies in the Ba+ cation and BaF molecule. The deviation of the calculated values from the experimental ones is of the order 10 cm−1 and is more than an order of magnitude better than the "chemical accuracy," 350 cm−1. The achievement of such an agreement has been provided, in particular, by the inclusion of the QED effects. The latter appeared to be not less important than the high-order correlation effects beyond the coupled cluster with single, double, and perturbative triple cluster amplitude level. We compare the role of QED effects for transition energies with heavier molecules—RaF and E120F, where E120 is the superheavy Z = 120 homolog of Ra. [ABSTRACT FROM AUTHOR]

The bandwidth adaptation factor (BAF), which is calculated as BW • (λ L - λ H): (d • f r), is a crucial evaluation parameter for designing ultrathin broadband absorbers. In this paper, a high BAF absorber is designed by utilizing an impedance frequency selective surface (FSS), which includes a six pinnacles FSS, a La-doped mullite ceramic dielectric layer and a metal backplane. The optimal numbers of pinnacled FSS is determined through comparison and optimization, and the power monitor results indicate that the main loss modes are electrical and ohmic loss. Subsequently, the impedance analysis reveals that the favourable absorption performance is attributed to good impedance matching and high loss coefficient. Furthermore, the observation of the current distribution on the surface confirms that the primary loss appears at the pinnacles. The proposed absorber has below −10 dB reflectivity in 12.26–18.00 GHz. Meanwhile, the BAF is 3.36 and the thickness is only 0.061 λ L (1.5 mm). The measured results are in good agreement with the simulation results, demonstrating an excellent BAF characteristic. [ABSTRACT FROM AUTHOR]

Er3+/Yb3+ codoped glass ceramics containing BaF2 crystals were obtained through a melt quenching process; the precipitation of BaF2 nanocrystals was confirmed by structural characterization. The effects of crystal quantity and size on the transmittance and upconversion fluorescence of the samples were analyzed. The precipitation of nanocrystals leads to a significant increase in upconversion luminescence intensity. The fluorescence spectra at different pump powers were measured. Er3+ and Yb3+ energy level diagrams and possible energy transfer routes during upconversion luminescence were explored. Furthermore, the functional relationship between temperature and the upconversion fluorescence intensity ratio of the samples was analyzed. When the temperature is 293 K, the relative sensitivity reaches the maximum of 1.38% K−1. [ABSTRACT FROM AUTHOR]

In this paper, Er3+ doped TeO 2 -ZnF 2 -BaF 2 -KF-Ta 2 O 5 tellurite glasses with low hydroxyl content (∼0.03 × 10−19 cm−3) were investigated employing both glass composition and glass melting process optimization. The Raman spectra and physical properties were characterized to analyze the structure of the glasses. Under the pumping of 980 nm LD laser, intense up-conversion fluorescence at 1.5 and 2.7 μm of samples and their lifetimes were detected and analyzed, and the related transition mechanisms with gradient-varying Er3+ doping concentrations were discussed. The maximum absorption and emission cross section at 2.7 μm was calculated to be 6.4 × 10−21 cm2 and 6.8 × 10−21 cm2, correspondingly, which were higher than those of traditional tellurite glasses. Using the calculated and measured spectroscopic parameters of bulk tellurite glass, a dual-wavelength pumping model was established to verify the feasibility of mid-infrared laser output in similar tellurite glass fiber. Experimental results support the assertion that the Er3+ doped tellurite glasses hold promise as a candidate laser gain medium for mid-infrared fiber laser systems. [ABSTRACT FROM AUTHOR]

In this work, we present the results of the analysis performed with near edge absorption fine structure spectroscopy of barium edges in a B+BaF2 optical filter. The radiation was generated by a laser-plasma soft X-ray source based on a double-stream gas puff target. The use of a flat-field spectrometer based on a diffraction grating allowed us to collect the absorption spectra of the radiation transmitted by the analyzed optical filter. The results demonstrate the appearance of clear M-edges of barium (M4 and M5). [ABSTRACT FROM AUTHOR]

Ionic redistribution at solid interfaces in ionic materials is the keystone of nanoionics. An experimental master piece has been provided by CaF2-BaF2 heterolayers. Meanwhile this system and the involved heterojunctions are extraordinarily well-understood. The present paper gives an account of this model system by reviewing not only transport experiments and defect-chemical modeling as a function of temperature and spacing of the individual layers, but also transition from semi-infinite to mesoscopic conditions, transition from Mott–Schottky to Gouy–Chapman behavior as well as the impact of ionic redistribution on the electronic minority carriers. Owing to the availability of bulk transport data, the analysis works well for in-plane and out-of-plane measurements with only the space charge potential as fit parameter. Space charge effects are able to provide an interpretation of the annealing behavior, too. The experiments are corroborated by molecular dynamics simulations. Extrapolating the ionic redistribution effects down to the atomic level may even explain homovalent doping effects in non-equilibrium mixtures of the two fluorides. [ABSTRACT FROM AUTHOR]

A series of high quality x%Pr3+:BaF2 (x = 0.6, 1, 2); (1%Pr3+, 2%Na+):BaF2; (1%Pr3+, y%Ca2+):BaF2 (y = 3, 5) and (0.6%Pr3+, 10%R3+):BaF2 (R = Y, Lu, Gd) crystals were grown by temperature gradient technique (TGT). The Raman spectra, absorption spectra, fluorescence spectra, and fluorescence decay lifetime were measured. XRD patterns indicate that the as-synthesized samples are pure BaF2 phase. The absorption cross-section of Pr3+ ions in the BaF2 matrix can be greatly improved by co-doping R3+ ions, while improvement by Na+ and Ca2+ ions is marginal. The fluorescence characteristic of Pr3+ ions can be effectively regulated by co-doping Na+, Ca2+, R3+ (R = Y, Lu, Gd) ions of different valence states. When R3+ ions are introduced, the fluorescence spectra show the strongest orange emission and the CIE chromaticity coordinates of Pr3+ ions are also in the orange region. When single-doped Pr3+ ions and Na+ or Ca2+ ions are introduced, the fluorescence lifetime of the 3P0 level is double exponential decay, and the short lifetime is the main proportion. However, the fluorescence centers tend to homogeneous and stable by R3+ ions co-doping and the fluorescence lifetime exhibits single-exponential decay, which is fitted to 49.7 μs, 47.8 μs and 49.6 μs of (0.6%Pr3+, 10%R3+):BaF2 (R = Y, Lu, Gd), respectively. All the results show that (Pr3+, Gd3+):BaF2 and (Pr3+, Na+):BaF2 are excellent laser gain media for high-efficiency orange and red laser operation. [ABSTRACT FROM AUTHOR]

• The OPP structure can operate in the violet light band. • The OPP structure realizes an angle selection within 30° range. • The OPP structure provides a new method to realize angle selection through ENZ principle. • The OPP structure can enhance angle selection sensitivity by incorporating dynamic anti-reflection structures. In this paper, an optical privacy protection (OPP) structure is designed for violet light, leveraging the unique epsilon-near-zero (ENZ) properties of YaBa 2 Cu 3 O 7 material along with an anti-reflection structure. To tackle the challenges posed by temperature regulation constraints, the zinc fluoride barium lanthanum aluminum magnesium hexafluoride glass is incorporated as the background medium. The findings indicate that this proposed configuration demonstrates a remarkable transmissivity exceeding 91 % in the TM wave for angles ranging from −30°∼ 30°. It is worth noting that the transmittance significantly drops close to zero beyond –33.7° or 33.7° angles. Moreover, an impressive transmittance of over 98 % is achieved within the TE wave range of −30°∼ 30°, while experiencing a sharp decline towards nearly zero beyond –33.9° or 33.9° angles. The designed OPP effectively operates across the frequency range of 680 ∼ 790 terahertz, encompassing the violet optical spectrum. It consistently exhibits a rectangular coefficient exceeding 0.84 in the TE wave and surpasses 0.87 in the TM wave, demonstrating its exceptional performance characteristics within these respective modes. [ABSTRACT FROM AUTHOR]

The properties of bulk contribution to sum-frequency generation reflected and transmitted by a finite layer in a multilayer system are described. The leading term is essentially due to the processes emitting in the transmission geometry, in particular for macroscopic layers. For such transmission processes, phase mismatch leads to the production of interference fringes when the layer thickness or a wavelength is tuned, which may be mistaken for resonant processes inside or at the surface of the material. Experimental evidence of such fringes measured from centrosymmetric bulks is provided for a diamond window in the far infrared and suggested for other materials in previously published data. The existence of a stationary point in the phase mismatch, related to the group velocity mismatch, is shown to be the source of another pseudo-resonant process in centrosymmetric calcium and barium fluorides, for which theoretical predictions reproduce the experimental observations. [ABSTRACT FROM AUTHOR]

Applications, such as high energy physics experiments at intensity frontier, time-of-flight positron emission tomography, ultrahigh repetition radiation imaging, and positron annihilation lifetime spectroscopy, etc., have raised increasing demands on the time response of scintillators. Development of ultrafast scintillators becomes one of focuses in recent studies. Barium fluoride (BaF2) crystal is a unique ultrafast scintillator with a sub-nanosecond fast scintillation component, its slow scintillation component with a decay time of about 0.6 μs, however, will cause serious pileups at high counting rates. As an effective approach to suppress the slow component in BaF2 crystals, doping has attracted continuous attention over the past three decades. This paper reviews the history of suppression of slow component in BaF2 crystals by doping, and then proposes basic principles on selecting doping elements. Suppression characteristic and mechanisms of slow component in BaF2 crystals doped with rare-earth metals (La, Y, Lu, Sc), alkali earth metals (Mg, Sr), transition metal (Cd), and alkali metal (K) are highlighted, and application research is introduced. The challenge and opportunity of slow component suppression by doping are also prospected. [ABSTRACT FROM AUTHOR]

The barium zirconate titanate coated with dopamine is an excellent dielectric material. Herein, we prepared a type of BaLaZrTiO3 (BLZT) powder by hydrothermal method and coated BLZT with dopamine (DA). Then, casting method was applied to synthesize a composite film by adding BLZT/DA‐BLZT powders to polyvinylidene fluoride (PVDF) respectively. Results show that DA‐BLZT@PVDF films perform better than BLZT@PVDF films in term of energy storage property and dielectric property. The dielectric constant and energy storage density of DA‐BLZT@PVDF films were all higher than that of BLZT@PVDF films and the dielectric loss was lower than BLZT@PVDF films. X‐Ray Diffraction (XRD) demonstrated the typical perovskite structure was existing in BLZT powder. TEM and SEM also showed that the surface of BLZT powder was successfully coated with DA and uniformly dispersed in PVDF. This research provided an avenue to significantly improve the electrical properties of composite films. [ABSTRACT FROM AUTHOR]

We present sub-50 fs soliton pulse generation from a diode-pumped Kerr-lens mode-locked laser based on an Yb3+-doped BaF2 crystal. Utilizing a spatially single-mode, fiber-coupled InGaAs laser diode at 976 nm as a pump source, the Yb:BaF2 laser generates pulses as short as 46 fs at 1060.1 nm with an average output power of 45 mW at a pulse repetition rate of ~65.6 MHz via soft-aperture Kerr-lens mode locking. To the best of our knowledge, this represents the first demonstration of Kerr-lens mode-locked operation of the Yb:BaF2 crystal, as well as the shortest pulse duration ever achieved from any diode-pumped mode-locked laser based on an Yb3+-doped alkaline-earth fluoride crystal. [ABSTRACT FROM AUTHOR]

In order to remove pollutants in domestic wastewater more completely, the anaerobic–anoxic–oxic (A2O)–membrane bioreactor (MBR)–biological aerated filter (BAF)–O3 combination process was studied. The ultrafiltration membrane was placed inside the A2O reactor to form an integrated reactor. The experimental water was sequentially degraded by A2O–MBR, BAF, and O3 reactor. The three operating parameters of hydraulic retention time (HRT), reflux ratio, and ozone contact time were optimized. The optimal conditions were found in the experiment: HRT was 10 h, reflux ratio was 200%, and ozone contact time was 15 min. Under these optimal conditions, the removal rates of chemical oxygen demand (COD), ammonia nitrogen, total nitrogen (TN), total organic carbon (TOC), UV254, and chroma were 96.00, 99.43, 82.46, 96.6, 93.20, and 79.00%, respectively. The effluent quality satisfied standard of Class IV surface water in China. The ultraviolet–visible and excitation-emission matrix spectra of water samples during the ozone oxidation were analyzed. It showed that the reaction was effective in removing chroma and humic acid-like substances in the wastewater. [ABSTRACT FROM AUTHOR]

A series of CoCrFeNiMn high-entropy alloy matrix self-lubricating composites were prepared by spark plasma sintering. The composites are composed of an FCC phase, Cr7C3, Ag, and eutectic fluoride BaF2/CaF2 phases. The microstructure of the composites is uniform. The additional phases distribute along the boundary of equiaxed grains of the FCC phase. The compressive yield strength and fracture toughness decrease with the increase of eutectic fluoride BaF2/CaF2. The composites are susceptible to brittle cleavage fracture. [ABSTRACT FROM AUTHOR]

Single-phase samples of the Ba1−xCexF2+x solid solution (x = 0.3–0.4) were synthesized by directional crystallization in the form of single crystals and by co-precipitation from aqueous nitrate solutions using potassium fluoride as a fluorinating agent in the form of nanopowders. The cathodoluminescence of the pressed powder samples was studied in comparison with the BaF2: Ce single crystals in 250–460 nm (2.7–5 eV) spectral range upon excitation by an electron accelerator. The cathodoluminescence spectra of the samples revealed a wide band in the range of 3.0–4.0 eV, which consists of two typical components of Ce3+ with decay time 23 ns in the case of single crystals and three decay times 27 ns, 140–170 ns, and ~600 ns in the case of pressed powders. The decay time of the short-wavelength component (27 ns) in the case of pressed powders is close to the lifetime of the excited state of the Ce3+ ion. The developed X-ray phosphors can be applied for embedding in diamonds for diamond–nanoparticle composite preparation. [ABSTRACT FROM AUTHOR]

Organic–inorganic composite scintillators, demonstrating advantages of easy large-area preparation and a high detection efficiency, have shown enormous potential application prospects in radiation detection and imaging. In this study, bulk polystyrene (PS) composite scintillators were successfully prepared by embedding inorganic BaF2 particles with a loading amount of up to 80 wt% during the polymerization process of the plastic scintillator. The inorganic BaF2 particles were uniformly dispersed in the organic matrix. With the increase of the loading amounts of BaF2 particles, the X-ray-excited luminescence intensity of the PS-BaF2 composite scintillators was about eight times higher than that of the commercial pure plastic scintillator. The scintillation counts under the gamma ray (59.5 KeV) irradiation also showed that the detection efficiency was obviously enhanced by BaF2 particle loading. More importantly, their scintillation pulse retains the decay kinetics of the organic matrix without loading the slow-decay component of BaF2. This work provides a promising solution for the application of the PS-BaF2 composite scintillator in high-efficiency radiation detection and large-area imaging. [ABSTRACT FROM AUTHOR]

Based on the literature data, the most used chemical element for the removal of the contaminant fluoride ions from different water systems was the Al followed by the Zr, Mg, Fe, C, and several others elements that form stable Me–F complexes. The application of mixed composite adsorbents is a modern tendency, but in this study, the dry aluminum sulfate was tested for direct chemical elimination of the fluoride ions from real industrial zinc sulfate electrolytes. The behavior of the used fluorine ion-selective electrode (FISE) was tested in the presence of sodium fluoride and aluminum sulfate. For suppression of the negative role of the aluminum ions on the FISE potential citrate total ionic strength adjustment buffer (TISAB) was used for appropriate ex situ analytical measurements of the fluoride ions in the real zinc electrolytes from the different hydrometallurgical purification stages. The elimination of the free fluorine ions was tested at room temperature (18–27 °C) and by heating up to 40 °C. The obtained results show that at room temperature, the efficiency of the reaction between F− and Al3+ ions was not very satisfied. Maximum 13% from the initial fluoride concentration was reduced at real conditions. By heating the process was intensified up to 75–95%, but in excess of non-reacted aluminum ions that additionally contaminated the electrolyte for zinc electrowining. The experimentally proven advantages and disadvantages revealed that the elimination reaction needs further optimizations before any applications at plant conditions. Factors as temperature was beneficial, whereas pH was hard for operation since the dry aluminum sulfate acidified the plant electrolytes and the zinc sulfate matrix precipitated easy by titration from acid to neutral conditions. [ABSTRACT FROM AUTHOR]

The short-wavelength sub-nanosecond luminescence in BaF 2 material, discovered in the early 80s, gave a new direction to research into fast scintillators and phosphors. In contrast to 'typical' luminescence occurring within the forbidden band gap, the new type of emission was due to transitions between the upper core and valence bands. Thus it was named core-valence luminescence (CVL); the terms cross-luminescence and Auger-free luminescence have also been used. Given its unusual nature, this new luminescence process has attracted considerable interest in the field of condensed matter physics. During the sequent decades (till the end of the previous century) CVL has been experimentally observed in several dozen compounds and the conditions for detecting CVL have been established. Interest in this kind of luminescence increased in recent years due to the emergence of new methods of crystal synthesis, the development of high-speed solid-state photodetectors, and the construction of unique modern set-ups using synchrotron radiation. This paper analyzes the numerous studies of CVL, obtained mainly over the past decade. Experimental and theoretical data on this topic are considered in detail. Special attention is given to new results on scintillation characteristics of BaF 2 in the form of single crystals, ceramics, nanoparticles, and composites. The features of CVL in binary and ternary compounds are discussed. Some Cs- and Ba-based ternary halides show relatively high light yields and represent promising fast scintillators. The prospects of using materials with CVL as fast scintillators for time-of-flight positron emission tomography and other applications are deliberated. • Overview of recent theoretical and experimental findings on Core Valence luminescence. • Most attractive CVL crystals for ultrafast scintillator applications analyzed. • Prospects for future studies and underexplored CVL materials listed. [ABSTRACT FROM AUTHOR]

Barium lanthanum fluoride powders have been prepared by reacting barium nitrate and lanthanum nitrate in molten sodium nitrate at 350 and 450°C, using a sodium fluoride as a fluorinating agent. A fivefold excess of sodium fluoride has been shown to prevent pyrohydrolysis. We have identified a phase of variable composition with the fluorite structure, Ba1–xLaxF2+x (0.3 < x < 0.5), which has high ionic conductivity (2.3 × 10–4 S/cm at 500 K) and an activation enthalpy for ionic transport of 0.50 ± 0.01 eV. [ABSTRACT FROM AUTHOR]

Four-wave mixing processes are ubiquitous in ultrafast optics and the determination of the coefficients of the χ(3) tensor is thus essential. We introduce a novel time-resolved ultrafast spectroscopic method to characterize the third-order nonlinearity on the femtosecond time-scale. This approach, coined as "nonlinear chirped interferometry," makes use of the variation of the optical group delay of a transmitted probe under the effect of an intense pump pulse in the nonlinear medium of interest. The observable is the spectral interference between the probe and a reference pulse sampled upstream and the metric is the transient swing of the probe group delay. We show that the detected signal is enhanced when the pulses are weakly chirped, and that, although interferometric, the method is intrinsically less sensitive to environmental phase fluctuations and drifts. By chirping adequately the reference pulse, the transient frequency shift of the probe pulses is also detected in the time domain and the detected nonlinear signal is enhanced. Nonlinear phase shifts as low as 10 mrad, corresponding to a frequency shift of 30 GHz, i.e., 0.01% of the carrier frequency, are detected without heterodyne detection or active phase-stabilization. The diagonal and/or non-diagonal terms of reference glasses (SiO2) and crystals (Al2O3, BaF2, CaF2) are characterized. The method is finally applied to measure the soft vibration mode of KTiOAsO4 (KTA). [ABSTRACT FROM AUTHOR]

The effect of BaF2, MgF2, and AlF3 on the structural and luminescent properties of gallo-germanate glass (BGG) doped with erbium ions was investigated. A detailed analysis of infrared and Raman spectra shows that the local environment of erbium ions in the glass was influenced mainly by [GeO]4 and [GeO]6 units. Moreover, the highest number of non-bridging oxygens was found in the network of the BGG glass modified by MgF2. The 27Al MAS NMR spectrum of BGG glass with AlF3 suggests the presence of aluminum in tetra-, penta-, and octahedral coordination geometry. Therefore, the probability of the 4I13/2→4I15/2 transition of Er3+ ions increases in the BGG + MgF2 glass system. On the other hand, the luminescence spectra showed that the fluoride modifiers lead to an enhancement in the emission of each analyzed transition when different excitation sources are employed (808 nm and 980 nm). The analysis of energy transfer mechanisms shows that the fluoride compounds promote the emission intensity in different channels. These results represent a strong base for designing glasses with unique luminescent properties. [ABSTRACT FROM AUTHOR]

A cross polarized wave (XPW) generation experiment with double BaF2 crystals in air was demonstrated with 120 µJ input pulse. A circular aperture was used to truncate the near field profile of the input beam and remove the outer part of the beam, and circularly symmetric beam profiles were generated at the BaF2 crystal positions. The measured focal spot size was close to the diffraction limit, and the energy stability of XPW was improved from ∼1.89% (without the aperture) to ∼0.67% (with the aperture). [ABSTRACT FROM AUTHOR]

Single crystals of Ca1– хBaхF2 (x = 0.001–0.05 and 0.85–0.99) solid solutions have been grown by the Bridgman method, and their thermal conductivity has been measured in the range 50–300 K by an absolute steady-state axial heat flow technique. The thermal conductivity of all samples has been shown to decrease with increasing temperature. At 300 K, the lowest thermal conductivity of the samples with x ≤ 0.05 exceeds 6 W/(m K), and that of the samples with x ≥ 0.85 is a factor of 2 lower. [ABSTRACT FROM AUTHOR]

Featured Application: laser surface-processing. Monocrystalline barium fluoride (BaF2) slab targets were irradiated by focused 46.9-nm laser radiation at various fluence levels above the ablation threshold. Well-developed ablation patterns with sharp edges were studied by AFM (atomic force microscopy). Their inner surfaces were uniformly covered by periodic structures. The spatial period of the ripples depends on the laser fluence. When the sample is rotated by 45°, the orientation of the grating-like structure changes accordingly. Thus, the grating vector of the periodic structure seems to be coupled to the crystallographic planes of the single crystal. This means that the XUV-laser induced ripples reported here differ from LIPSS (laser-induced periodic surface structures) associated with interference phenomena occurring on illuminated surfaces. Therefore, other mechanisms are discussed to explain the formation of the periodic nanostructures reported in this article. [ABSTRACT FROM AUTHOR]

The anodic dissolution of the Mn5Si3 electrode in 0.5 M H2SO4 + (0.0025–0.05) M NaF solutions is studied by the methods of polarization, capacitance, and impedance measurements. The kinetic order of the reaction of dissolution of silicide with respect to NaF as a function of the potential and the differential capacitance as a function of the potential and the concentration of NaF are calculated. It is shown that the effect of sodium fluoride, which activates the anodic dissolution of Mn5Si3 in a sulfuric acid solution, is associated with a weakening of the passivating effect of oxygen-containing silicon compounds and manganese oxides; with an increase in the concentration of NaF, the role of manganese in the kinetics of anodic processes on silicide increases and the role of silicon decreases. The mechanisms and kinetic laws of the anodic processes taking place on the Mn5Si3 electrode are discussed. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of multicolor light-emitting nanomaterials based on rare earths (RE3+) are of great importance due to their possible use in optoelectronic devices, such as LEDs or displays. In the present work, oxyfluoride glass-ceramics containing BaF2 nanocrystals co-doped with Tb3+, Eu3+ ions were fabricated from amorphous xerogels at 350 °C. The analysis of the thermal behavior of fabricated xerogels was performed using TG/DSC measurements (thermogravimetry (TG), differential scanning calorimetry (DSC)). The crystallization of BaF2 phase at the nanoscale was confirmed by X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM), and the changes in silicate sol–gel host were determined by attenuated total reflectance infrared (ATR-IR) spectroscopy. The luminescent characterization of prepared sol–gel materials was carried out by excitation and emission spectra along with decay analysis from the 5D4 level of Tb3+. As a result, the visible light according to the electronic transitions of Tb3+ (5D4 → 7FJ (J = 6–3)) and Eu3+ (5D0 → 7FJ (J = 0–4)) was recorded. It was also observed that co-doping with Eu3+ caused the shortening in decay times of the 5D4 state from 1.11 ms to 0.88 ms (for xerogels) and from 6.56 ms to 4.06 ms (for glass-ceramics). Thus, based on lifetime values, the Tb3+/Eu3+ energy transfer (ET) efficiencies were estimated to be almost 21% for xerogels and 38% for nano-glass-ceramics. Therefore, such materials could be successfully predisposed for laser technologies, spectral converters, and three-dimensional displays. [ABSTRACT FROM AUTHOR]

A BaF(p-BDC)0.5 catalyst was prepared by solid state reaction at room temperature with Ba(OH)2 as precursor, NH4F as F source, and H2(p-BDC) as organic ligand. The calcined samples were used as catalysts for dehydrochlorination of 1-chloro-1,1-difluoroethane to generate vinylidene fluoride (VDF) at 350 °C. Commercial production of VDF is carried out at 600–700 °C. Clearly, pyrolysis of the BaF(p-BDC)0.5 catalyst provided a promising way to prepare VDF at low temperatures. Prior to calcination, the activity of the BaF(p-BDC)0.5 catalyst was low. Following calcination at high temperatures, BaF(p-BDC)0.5 decomposed to BaF2 and BaCO3, and then the catalyst was chlorinated and fluorinated to BaClF, which showed high activity and stable VDF selectivity for dehydrochlorination of 1-Chloro-1,1-Difluoroethane to VDF. [ABSTRACT FROM AUTHOR]