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The local environment of a barium monofluoride (BaF) molecule embedded in an argon matrix is calculated. A substitution of a BaF molecule for four Ar atoms is found to be strongly favoured compared to substitutions for other numbers of Ar atoms. The equilibrium positions of the BaF molecule and its nearby Ar neighbours are found by minimising the total energy. The potential barrier that prevents the migration of the BaF molecule within the solid and the barrier that prevents its rotation are calculated. At the cryogenic temperatures used by the EDM 3 collaboration, these barriers are sufficiently large to fix the position and orientation of the molecule. Knowledge of the local environment of matrix-isolated BaF molecules is essential for the EDM 3 collaboration, which is using them in a precision measurement of the electron electric dipole moment. [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]

Pr3+ doped high density germanate glasses were prepared by the melt-quenching method. The physical and luminescent properties were investigated. The glass containing BaF 2 represented maximum phonon energy of 810 cm−1, and the glass density was greater than 6 g/cm3. The glass exhibited good radiation resistance under 2 h of X-ray irradiation. Intense blue, green emissions and weak red emissions were observed when the glass was excited by X-ray, and the blue fluorescence lifetimes were in the range of 9.15–12.59 μs The results show that Pr3+ doped germanate glass could be a potential scintillating material in the field of X-ray detection for fast events. [ABSTRACT FROM AUTHOR]

This study presents a pioneering experimental demonstration of dual-wavelength laser operation at 2.8 μm and 3.6 μm in an Er3+-doped ZrF 4 -BaF 2 -YF 3 -AlF 3 double-cladding fluoride glass fiber, fabricated in-house. The achievement is realized through the implementation of a novel dual-wavelength pumping scheme utilizing 980 nm and 1150 nm lasers. This innovative scheme enables the excitation of the lower energy level of the 2.8 μm laser transition (4I 11/2) to the upper energy level of the 3.6 μm transition (4F 9/2) via an excited state absorption process, resulting in simultaneous emission at 2.8 μm and 3.6 μm. The maximum laser output powers at 2.8 μm and 3.6 μm are measured at 0.96 W and 0.32 W, respectively. This groundbreaking work marks the first experimental realization of dual-wavelength laser operation at 2.8 + 3.6 μm in Er3+-doped fluoride fiber, contributing significantly to the advancement of laser technology in this spectral range. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic field led to shift of peaks of photoluminescence of nanopowders CaF 2 and BaF 2. • Peaks transformation is a result of interaction of nanofluorides defect magnetic field. • There are the split of the first peak to a quadruplet, and the second to a doublet. This work establishes for the first time that imposing of permanent magnetic field ledt o shift of peaks in ranges of photoluminescence of nanopowders CaF 2 and BaF 2. Ranges of shift of peaks to the red area of a spectrum depended on the size of magnetic field. A transformation of peaks occurs as a result of interaction of own magnetic field of nanofluorides with external magnetic field caused by structural defects of nanopowders. Deconvolution of spectra allowed to identify the split of the first peak of both nanofluorides to a quadruplet, and the second to a doublet at the size of magnetic field of 0.1 T. At increase in magnetic field the quadruplet of the first peak disappears, and the doublet of the second significantly differs for ferromagnetic CaF 2 and para -ferromagnetic BaF 2. Besides, spectra of both nanofluorides contain peaks at 616 nm that aren't observed in the field of 0.1 T but appear in the field of 0.15 T, and are possibly caused by the center of coloring. [ABSTRACT FROM AUTHOR]

Lithium-based fluoride salts are one of the leading options as fuel matrix in Molten Salt Reactors. The understanding of their thermodynamic behavior, e.g. chemical stability, activity, as well as heat transfer properties, in the reactor's environment is crucial for the safety assessment. In this work, the chemical equilibria of lithium fluoride with two important fission products dissolved in the salt matrix, namely barium fluoride and zirconium fluoride, are considered. The phase diagrams of the binary systems ▪ , ▪ and ▪ , as well as the ternary system ▪ are assessed by the CALPHAD (CALculation of PHase Diagram) method using the quasichemical model in the quadruplet approximation for the liquid solution. These models are based on literature and new experimental data, and provide a good overview of the stability of intermediate compounds formed in the various systems and of the liquid solution. • Phase diagram measurements in LiF − BaF 2 are reported, that solve discrepancies noticed in the literature. • A thermodynamic model of the LiF − BaF 2 − ZrF 4 system is reported based on the quasi-chemical formalism. • Mixing enthalpy data available on this system are reproduced very well by the model. [ABSTRACT FROM AUTHOR]

In mammalian cell nuclei, the nuclear lamina (NL) underlies the nuclear envelope (NE) to maintain nuclear structure. The nuclear lamins, the major structural components of the NL, are involved in the protection against NE rupture induced by mechanical stress. However, the specific role of the lamins in repair of NE ruptures has not been fully determined. Our analyses using immunofluorescence and live-cell imaging revealed that the nucleoplasmic pool of lamin C rapidly accumulated at sites of NE rupture induced by laser microirradiation in mouse embryonic fibroblasts. The accumulation of lamin C at the rupture sites required both the immunoglobulin-like fold domain that binds to barrier-to-autointegration factor (BAF) and a nuclear localization signal. The accumulation of nuclear BAF and cytoplasmic cyclic GMP-AMP synthase (cGAS) at the rupture sites was in part dependent on lamin A/C. These results suggest that nucleoplasmic lamin C, BAF, and cGAS concertedly accumulate at sites of NE rupture for rapid repair. [ABSTRACT FROM AUTHOR]

Barium fluoride (BaF2) crystal is known as the fastest scintillation crystal, which has a wide application prospect in high energy physics, nuclear physics and nuclear medicine. It is very important to suppress the slow luminescence component of BaF2 crystal for its engineering application. BaF2 crystals with high Y3+ doping concentration 5%, 8%, 10% (mole fraction) were prepared by Bridgman method, and the co-doped BaF2 fast response scintillation crystals were prepared by codoping Y3+ with alkali metal ions (Li+, Na+) to form charge compensation to eliminate the generation of interstitial F-. Then, based on the optimized 5 ns and 2 500 ns time gate width measurement methods, the effects of Y3+ doping concentration and the co-doping concentration of Y3+ and alkali metal ions (Li+, Na+) on the fast/ slow component ratio of BaF2 scintillation crystal were studied. The results show that the optical quality of the high concentration Y3+ doped BaF2 crystals is excellent, and the transmittance at 220 nm and 300 nm is higher than 90% and 92%, respectively. With the increase of Y3+ doping concentration from 0 to 10%, the slow luminescence component of BaF2 crystal decrease significantly, and the fast/ slow component ratio increase from 0.15 to 1.21. The slow luminescence component of the grown Y3+ / Li+ and Y3+ / Na+ co-doped BaF2 crystals are further decrease compared with that of the Y3+ doped BaF2 crystals, and the highest fast/ slow component ratios obtained are 1.63 and 1.61, respectively. The co-doped BaF2 fast response scintillation crystal is expected to be applied in the frontier experiments of high energy physics and nuclear physics. [ABSTRACT FROM AUTHOR]

Lu 2.94 Al 5 O 12 :0.06Ce3+ phosphors and LiF–, NaF–, and BaF 2 –added Lu 2.94 Al 5 O 12 :0.06Ce3+ phosphors were prepared by a sol−gel process. The effects of synthesizing temperature and fluoride fluxes such as LiF, NaF, and BaF 2 on the photoluminescence properties of Lu 2.94 Al 5 O 12 :0.06Ce3+ phosphors are systematically investigated. The increase in synthesizing temperature and the addition of fluoride fluxes significantly enhance the photoluminescence properties due to the improvement in crystallinity. All the phosphors exhibit a green–yellow emission due to the 2D 3/2 → 2F 5/2 , 7/2 transitions of Ce3+. Of the prepared phosphors, the 6 wt% BaF 2 –added Lu 2.94 Al 5 O 12 :0.06Ce3+ phosphor synthesized at 1400 °C shows the highest emission intensity, which is 173% stronger than that of the flux–free Lu 2.94 Al 5 O 12 :0.06Ce3+ phosphor. [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]

A novel boro-bariofluoride/sodium/calcium/nickel glasses with chemical compositions (40-x)B2O3·30BaF2·15CaO·15Na2O·xNiO, where x = 0.0 (Ni0.0)–1.5 (Ni1.5) in steps of 0.3 mol% were prepared using the conventional melt quenching technique. Physical and optical features as well as ionizing radiation resistance capacities of the synthesized glass have been examined using various characterization techniques. Radiation shielding abilities have been examined via Phy-X/PSD software. Amorphous state of the Ni-glasses was confirmed by XRD data. Addition of NiO increased the density of glasses from 3.53 to 3.80 g/cm3. The direct optical band gap ( E Direct Optical ) was reduced from 3.58 to 3.33 eV, while the indirect ( E Indirect Optical ) one was reduced from 3.08 to 2.84 eV. Urbach's edge (EU) was enhanced from 0.4197 to 0.5009 eV as NiO content increased from 0.0 to 1.5 mol%. At a certain wavelength λ = 500 nm, the values of refractive index (n) increased from 1.84 to 2.56. In the photon energy range (0.15–15 MeV), the mass attenuation coefficient (MAC) results had the following trend: (MAC)Ni0.0 < (MAC)Ni0.3 < (MAC)Ni0.6 < (MAC)Ni0.9 < (MAC)Ni1.2 < (MAC)Ni1.5. The linear attenuation coefficient (LAC) showed a similar trend of the MAC. In the same photon energy range, the half value layer (HVL) of Ni-glasses was reduced as NiO level increased, i.e. (HVL)Ni0.0 > (HVL)Ni0.3 > (HVL)Ni0.6 > (HVL)Ni0.9 > (HVL)Ni1.2 > (HVL)Ni1.5. The effective atomic number (Zeff) of the prepared Ni-glasses has the same trend of MAC and LAC shielding parameters. The Ni-glasses can be applied in optical areas and considered as superior light glasses for radiation shielding applications. [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]

In this study, a novel perovskite oxyfluoride BaY 0.5 Zr 0.5 O 2.5 F 0.5 was prepared by a solid-state reaction using BaCO 3 , ZrO 2 , Y 2 O 3 and BaF 2 as raw materials. The synthetic process of BaY 0.5 Zr 0.5 O 2.5 F 0.5 , the effect of the mole ratio of raw materials, and sintering temperature on the phase composition were investigated, and the structure of BaY 0.5 Zr 0.5 O 2.5 F 0.5 was characterized. The results indicated that the pure oxyfluoride compound BaY 0.5 Zr 0.5 O 2.5 F 0.5 was successfully synthesized after sintering at 1400 °C for 24 h with 15% mol excess BaF 2. The grains of BaY 0.5 Zr 0. 5O2.5 F 0.5 were of a regular columnar shape with a size of 0.5–2 μm. The space group of BaY 0.5 Zr 0.5 O 2.5 F 0.5 was Pm-3m with a = 4.2819 Å. In this simple perovskite structure, Ba atoms occupied the body center of the structure, Y and Zr atoms were disordered in the B site, and O and F atoms were disordered in the X site, with the occupation of 83% O atoms and 17% F atoms. In addition, introducing F− ions into oxygen vacancies made BaY 0.5 Zr 0.5 O 2.5 F 0.5 more stable and decreased the lattice content. This study provides new insights into the modification method of perovskite. [ABSTRACT FROM AUTHOR]

Our study aimed to investigate the effect of ZnNPs formulated by spinach extract (SPE-ZnNPs) fluoride induced hepato-renal toxicity in rats. 18 male rats were divided into three groups (n=6); Control, NaF and NaF + SPE-ZnNPs. various biological parameters and histopathological analysis were estimated. Phytochemical of spinach and characterizations of ZnNPs were analyzed using standard technics. Results show that the plant is rich in active substances and ZnNPs were formulated with a size of up to 30 nanometers, which is proven by the Uv-VIS, FTIR and SEM results. Results show that NaF exposed induce an alteration in hemato-biochemical parameters, and hepato-renal oxidative stress and histopathological alteration. However, SPEZnNPs' administration to NaF rats resulted in a partial improvement and correction of the prior parameters. Use of SPE-ZnNPs appears to be the main preventative measure against fluoride poisoning and the oxidative stress it causes. [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.

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.

In this study, a novel technique called heterocoagulation was employed to fabricate solid lubricant doped ceramic matrix composite powder for plasma spraying. Zeta potential of all the ceramic materials (Al₂O₃, TiO 2 , YSZ, Cr 2 O 3 , and Al₂O₃-TiO₂), solid lubricants (hBN, WS 2 , MoS 2 , BaF 2 , CaF 2) with and without surfactants, and heterocoagulated powders were measured. Effective heterocoagulation occurred for Al₂O₃/BaF₂, YSZ/WS₂, YSZ/BaF₂, Al₂O₃-TiO₂/WS₂, and Al₂O₃-TiO₂/BaF₂ composites. The composite powders were characterized using SEM and XRD. The wettability test of BaF 2 and CaF 2 with ceramic materials revealed that Al₂O₃, Cr₂O₃, and Al₂O₃-TiO₂ were highly wettable by CaF 2. Whereas, BaF 2 displayed excellent wetting characteristics with all the ceramic coating layers. From the zeta potential and wettability results, YSZ can be selected as the ceramic matrix, and WS 2 and BaF 2 , respectively as low and high-temperature solid lubricants for plasma spraying. [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]

[Display omitted] • Deep eutectic system of ZrCl 4 /urea is devised to uniformly incorporate Zr with C 3 N 4. • Fluoride adsorption capacity of CN-Zr reaches 145.34 mg/g in hydrochloric acid. • Various Zr sources are considered on the performance and metal leaching rate. • Structural features and fluoride existence form in acid are considered in mechanism. • The adsorption cost of 0.3157 CNY/g indicates substantial industrial applicability. The fluorine chemical industry's rapid growth demands efficient strategies for treating and utilizing the costly and inefficient byproduct, fluoride-containing hydrochloric acid, posing a significant challenge. In this study, a cost-effective method was developed for preparing an acid-resistant and efficient defluorination material. Carbon nitride (C 3 N 4) was chosen for its exceptional acid resistance and was modified via template-free doping with different zirconium source. Characterization results through XRD, FTIR, BET, XPS, SEM, and TEM confirm the successful synthesis of CN-Zr using zirconium chloride (ZrCl 4) with a specific surface area of 87.77 m2/g. Furthermore, the adsorption results indicate outstanding fluoride adsorption performance of CN-Zr in hydrochloric acid, with a maximum adsorption capacity of 145.34 mg/g and minimal zirconium leaching. Moreover, the adsorption mechanism was systematically studied using Zeta potential, FTIR and XPS characterization. The findings indicate that Zr was integrated with C 3 N 4 uniformly by forming a deep eutectic system (DES), utilizing exposed terminal amino groups for effective hydrogen bonding with HF which predominates as the primary fluorine existence in hydrochloric acid. Meanwhile, the enhanced ion exchange, complexation of Zr-F and strong electrostatic attraction all contribute to improving adsorption. Finally, the assessment of recyclability performance and operation cost demonstrate that the material can maintain 80% of its initial adsorption capacity after five cycles. The cost analysis results indicate that the adsorption cost is only 0.3157 CNY/g, making it considerable competitive in the industry. [ABSTRACT FROM AUTHOR]

Group-II fluorides (BaF 2 and MgF 2) insulators are deposited on hydrogenated (C–H) diamonds by E-beam evaporator at room temperature. The bandgaps, chemical bonds and band offsets of fluorides are investigated by the high-resolution X-ray photoelectron spectroscopy (XPS) measurements. The XPS results show bandgap energies of 9.4 ± 0.2 eV for BaF 2 and 9.7 ± 0.2 eV for MgF 2 by F 1s energy loss spectra. The valence band offsets (ΔE V 's) of BaF 2 /MgF 2 on the C–H diamond are determined as 5.2 ± 0.2 and 4.8 ± 0.2 eV, respectively. There are both type II energy band configuration for BaF 2 and MgF 2 on the C–H diamond with conduction band offsets of 1.3 ± 0.2 eV and 0.6 ± 0.2 eV, respectively. The relatively oxygen-weak or oxygen-free fluoride/C–H diamond interface and large ΔE V suggest that fluorides are an excellent gate dielectric for the C–H diamond field-effect transistors with high hole mobility and low gate leakage. [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]

• We have demonstrated a mid-infrared (MIR) device exhibiting exceptional circular dichroism (CD), utilizing multilayer films composed of α-phase molybdenum trioxide (α-MoO 3) and BaF 2. • It is found that the proposed structure achieves a remarkable absorption efficiency of 0.99 for left circularly polarized light at 12 μm, accompanied by a maximum CD in reflection of 0.93 and a resonant Q-factor of 111. • The strong chirality originates from the symmetry breaking of the structure. • The proposed chiral structure demonstrated exceptional responses across a broad range of wavelengths, highlighting its remarkable adaptability and versatility to accommodate various optical frequencies. As an emerging natural biaxial hyperbolic material, α-phase molybdenum trioxide (α-MoO 3) exhibits the excellent anisotropy and unique electromagnetic manipulation properties, which further stimulates the potential for polarization manipulation. Here, a Fabry-Perot cavity chiral structure based on multilayer films of α-MoO 3 and BaF 2 is presented, which exhibits excellent circular dichroism (CD) by displaying different reflectance properties for left-hand circular polarization and right-hand circular polarization light in the mid-infrared range. The numerical simulation results demonstrate that the chiral structure exhibits a remarkable absorption efficiency of 0.99 for left circularly polarized light at a wavelength of 12 μm, accompanied by a maximum CD in reflection of 0.93 and a resonant quality factor (Q-factor) of 111. This exceptional performance arises from the relative twist between α-MoO 3 and the underlying BaF 2 thin film, which simultaneously breaks the rotational and mirror symmetries of the chiral structure. To gain a deeper understanding, we further investigate the influence of film thickness and relative rotation angle on the optical properties of the chiral structure. By adjusting the geometric parameters of the chiral structure, it becomes possible to tune the chiral resonance wavelength and the corresponding CD value, providing a novel approach for the development of tunable chiral optical devices. This study offers new insights into the fabrication of low-cost chiral structures with high-Q resonances and their potential applications in the mid-infrared range, laying the foundation for the development of more powerful and controllable chiral optical devices. [ABSTRACT FROM AUTHOR]

A new alkaline-earth and Gd3+ borate, Ba 5 Gd 3 (BO 3) 6 F, has been successfully grown through a high-temperature solution method employing a BaF 2 -NaF-B 2 O 3 flux. This compound crystallizes in the monoclinic space group P 2 1 / c with lattice parameters of a = 13.679(4) Å, b = 8.694(3) Å, c = 7.664(2) Å, β = 99.116(7)°, V = 899.9(5) Å3, and Z = 1. Its three-dimensional structure consists of the [Ba/GdO] polyhedra and [FBa 4 Gd 2 ] octahedra layers. Magnetic analysis reveals that Ba 5 Gd 3 (BO 3) 6 F exhibits a magnetocaloric effect with a maximum −ΔS m of 29.86 J kg–1 K–1 at 3 K and 9 T. Additionally, the thermal stability, along with infrared (IR) and ultraviolet–visible–near-infrared (UV–Vis–NIR) diffuse reflectance spectra, were thoroughly examined. First-principles calculations further explored the electronic band structure and densities of states. A new Ba 5 Gd 3 (BO 3) 6 F single crystal has been obtained using a high-temperature solution method with BaF 2 -NaF-B 2 O 3 system as flux. Ba 5 Gd 3 (BO 3) 6 F exhibits paramagnetism and demonstrates a magnetocaloric effect with a –ΔS m value of 29.86 J kg−1 K−1 at 3 K and 9 T, approaching its paramagnetic limit. [Display omitted] • A new borate, Ba 5 Gd 3 (BO 3) 6 F, was obtained. • The magnetocaloric properties of Ba 5 Gd 3 (BO 3) 6 F were investigated. • Ba 5 Gd 3 (BO 3) 6 F exhibits a maximum −ΔS m reaching 88.11 % of the theoretical value. • Ba 5 Gd 3 (BO 3) 6 F has high stability. [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]

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]

The temperature dependences of the heat capacity (Cp(T)) and crystal lattice parameters (a(T) and Vu(T)) of barium difluoride, BaF2, as well as the heterovalent (BaF2)0.59(TmF3)0.41 solid solution, in the temperature range of 2–300 K are experimentally studied. Anomalous deviations of the dependences of Cp(T), a(T) and Vu(T) of the solid solution at low temperatures (2–20 K) both in the direction of higher and lower values, due to the rearrangement of the crystal field, as well as the appearance of two-level systems in the metal sublattice of the solution, are revealed. At elevated temperatures (150–300 K), an anomalous feature of the studied characteristics with a deviation towards lower values is also observed, which we attribute to the increased influence of the anharmonicity of the vibrations of the solution lattice. It is established that the occurrence of the mechanisms of the revealed anomalies may be attributed to the structural disorder of the solid solution due to the random nature of the placement of Tm3+ ions when replacing Ba2+ ions in the metal sublattice, as well as the appearance of F− ions in the interstitial spaces of the barium difluoride structure. [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]

Because of its fast scintillation peaked at 220 nm with a decay time of less than 0.6 ns, barium fluoride crystals have attracted broad interest in the community pursuing ultrafast detectors for future high energy physics (HEP) experiments and GHz hard X-ray imaging for future X-ray free-electron laser (XFEL) facilities. A crucial issue for its application is the spectral response of photodetectors down to vacuum ultraviolet (VUV). In this article, we compare quantum efficiency (QE) and photon detection efficiency (PDE) spectra measured for several ultraviolet (UV) photodetectors down to 200 nm. Their figures of merit on the detection efficiency for the fast component and the suppression of the slow component are also discussed. [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]

Using the Bridgman-Stockbarger method, crystals of triple fluoride CaF2-SrF2-BaF2 were grown in a composition range similar to that of CaSrBaF6. The crystals were 10-12 mm in diameter and 50–60 mm in length. The CaSrBaF6 crystal is a new optical material which is transparent in the mid-IR, visible and UV ranges. The uneven distribution of the components along the length of the crystal did not exceed 10 %. The edge of the absorption band in the IR range was 14.3 μm, and the optical absorption at the wavelength of 200 nm did not exceed 18 % (less than 0.2 cm–1). The refraction indices were 1.4527, 1.4488, and 1.4458 for the wavelengths of 633, 969, and 1539 nm respectively. The crystal melts in the temperature range of 1150–1210 °С. The CaSrBaF6 composition is an appropriate matrix for doping with rare-earth ions in order to obtain functional single-crystal and ceramic materials of the visible and IR ranges.

The aim of this study was to investigate the structural and optical properties of mixed alkaline earth fluoroborate glasses with compositions of xBaF2–(50–x)CaF2–50B2O3 (x = 5–30 mol%) synthesized using the melt-quenching technique. The glass characterization included X-ray diffraction (XRD), Fourier transform infra-red (FTIR), and optical absorption spectra analysis. Based on the XRD results, the absence of a sharp peak at x = 5–30 mol% indicated the absence of long-range order and confirmed the glass matrix's amorphous nature. Furthermore, the FTIR spectroscopy revealed that the replacement of calcium fluoride (CaF2) with barium fluoride (BaF2) in the network resulted in the alteration of trigonal boron (BO3) units into tetrahedral B4 units, which contained tetrahedral boron (BO4) and oxyfluoroborate tetrahedral (BO3F) units. Moreover, the energy bandgap (Eopt) varied from 3.18 to 3.58 eV for direct transition and from 2.74 to 3.12 eV for indirect allowed transition. Both Eopt increased from x = 5–30 mol% with a sharp increase from x = 15–20 mol%. The increase of both Eopt was due to the increase in bridging oxygen formation, while the sharp increase at 15 ≤ x ≤ 20 mol% was associated with the abrupt decrease in nonbridging oxygen (NBO) due to the mixed alkaline earth effect (MAEE) in the region. Meanwhile, the decrease in refractive index from 2.35 to 2.26 with a sharp drop between 15 and 20 mol% was associated with the decrease in electron packing density and the lower polarizing power of BaF2 compared to CaF2. The electronic polarizability of oxide/fluoride ions and optical basicity showed an anomalous minimum at 25 mol%, suggesting the influence of MAEE on both properties in the region. This study concluded that the mixed alkaline earth fluoroborate glass synthesized using the melt-quenching technique demonstrated the presence of MAEE through the anomalies in the structural and optical parameters of the presently studied glasses. [ABSTRACT FROM AUTHOR]

Yb3+/Ho3+ codoped and Yb3+/Er3+/Ho3+ tridoped TeO 2 –BaF 2 –LaF 3 –La 2 O 3 (TBLL) fluorotellurite glasses with low OH− absorption (0.026 cm-1), high glass transition temperature (434 °C) and low phonon energy (784 cm-1) were prepared. Their mid-infrared fluorescence properties and related energy transfer (ET) mechanism were studied under 980 nm excitation. A strong emission at 2.85 μm was realized in Yb3+/Ho3+ codoped tellurite glass, which was attributed to the high-efficiency ET from Yb3+ ions to Ho3+, and the ET efficiency was 91.1%. Further introduction of Er3+ ions induced stronger 2.85 μm emission, and the ET efficiency was improved to 96.2%, ascribed to the establishment of more ET channels and Er3+ ions playing the role of ET bridge between Yb3+ and Ho3+ ions. These results indicate that the Yb3+/Er3+/Ho3+ tridoped tellurite glass could be a hopeful gain medium material for the ∼3 μm fiber laser. [ABSTRACT FROM AUTHOR]

Elastic modulus and hardness of thin-films are critically important in determining the behaviour of free-standing actuatable microstructures. In this study, nanoindentation has been used to investigate the mechanical properties of thermally evaporated Ge and BaF2 thin-films. Nanoindentation experiments indicate that Ge and BaF2 thin-films are characterised by a reduced modulus of 95 ± 3 GPa and 33 ± 9 GPa, respectively, and hardness of 4.6 ± 0.4 GPa and 0.75 ± 0.4 GPa, respectively. The elastoplastic response of both thin-films was predominantly elastic for low indentation loads, but exhibited plasticity ≥ 60% for indentation loads approaching 8 mN. Indentation-induced creep deformation was found to be limited to ≤ 5%. [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]

Structural properties of topological insulator bismuth telluride filmsgrown epitaxially on (111) BaF2 with a fixed Bi2Te3 beam flux were systematically investigated as a function of substrate temperature and additional Te flux. A layer-by-layer growth mode is observed since the early stages of epitaxy and remains throughout the whole deposition. Composition of the epitaxialfilms produced here stays between Bi2Te3 and Bi4Te5, as determined from the comparison of the measured x-ray diffraction curves with calculations. The substrate temperature region, where the growth rate remains constant, is found to be the most appropriate to obtain ordered Bi2Te3films. Line width of the L = 18 Bi2Te3diffraction peaks as low as 140 arcsec was obtained, indicating high crystalline quality. Twinning domains density rises with increasing growth temperature and reducing Te extra flux. X-ray reflectivity curves of pure Bi2Te3films with thickness from 165 to 8 nm exhibited well defined interference fringes, evidencing homogeneous layers with smooth surface. Our results demonstrate that Bi2Te3films with very well controlled structural parameters can be obtained. High structural quality Bi2Te3films as thin as only eight quintuple layers grown here are promising candidates for intrinsic topological insulator. [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 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]

An innovative method for utilizing synthetic calcium fluoride (CaF2), recovered from fluoride-containing semiconductor wastewater, and waste sulfuric acid (H2SO4) to produce hydrofluoric acid (HF) was investigated. The research was set to study the low-temperature production of HF via reaction of synthetic CaF2 and waste H2SO4. The impact of four factors, including H2SO4 concentration, total volume (H2SO4 + H2O)/CaF2 ratio, drying temperature of synthetic CaF2, and reaction carried out under different temperature, on HF productivity was investigated in this study. HF yield increased with increasing H2SO4 concentration and total volume/CaF2 ratio under room temperature. Generally, reactions carried out under low-temperature (< 100 °C) had a positive impact on HF yield. The higher temperature led to an increase in absorbed-HF but a decrease in total-HF. The reaction of commercial CaF2 and 70% H2SO4 had a higher absorbed-HF yield of 61.7% than synthetic CaF2 and 70% waste H2SO4, which had a yield of 36%. This was due to the higher purity of the commercial CaF2 and fewer interference ions in H2SO4. HF productivity was lowered by CaSO4, which hindered the reaction of reactants and also the generation of fluorosulfuric acid. [ABSTRACT FROM AUTHOR]

Barium fluoride (BaF2) crystals are attracting much attention as efficient inorganic scintillator promising for high‐energy physics, industrial inspection, and other fields because of the fast component of the decay time (0.6 ns) and high radiation resistance. However, two major drawbacks limit its practical application: (i) a slow decay time of ~600 ns is derived from self‐trapping excitons; (ii) the absolute light yield from the fast luminescence component is not competitive. The introducing of rare earth ions and preparation of BaF2 polycrystalline ceramics is considered to be effective measures to solve these bottlenecks. Pr3+ is extremely suitable as the activated ion of scintillation materials, which possess emission peaks located in visible band and the faster 5d–4f transition. In this work, highly sinterable Pr3+:BaF2 precursor powder was synthesized via the coprecipitation method by adjusting the reactant concentration and temperature. The morphology and microstructure of as‐synthesized powders were characterized using scanning electron microscopy (SEM) and transmittance electron microscopy analysis. The 5 at.% Pr3+:BaF2 transparent ceramic with a transmittance of 50.7% at the wavelength of 500 nm was fabricated by hot pressing the as‐prepared powders at 900°C for 4 h under the axial pressure of 50 MPa. The SEM images of ceramic cross‐section show that the residual pore is the main light scattering source. The absorption and emission spectrum of ceramic samples were discussed. [ABSTRACT FROM AUTHOR]

We investigate the effects of deposition temperature on a crystal structure and electrical and optical properties of PbTe thin films sputtered on BaF2 (111). We observe that with the increase in deposition temperature, the grain size increases, and when it reaches 300 °C, the grain size reaches the maximum, and the preferred orientation begins to change. At 400 °C, the lattice mismatch rate decreases from 4.2% to 3.6% due to lattice contraction caused by reevaporation, and the conduction type changes from p-type dominated by a mismatch strain defect to n-type dominated by a Te vacancy. These changes lead to the interplay of various absorption mechanisms. We find that, in addition to the overall absorption coefficient curve significantly changing with deposition temperature, more importantly, the contribution of various internal absorption mechanisms to the below bandgap absorption spectrum does no longer synchronize. Instead, the contribution of an acoustic phonon to free-carrier absorption (FCA) decreases, while the relative contribution of optical phonon, impurity, two-photon absorption (2PA), and three-photon absorption (3PA) increases. This regulation effect reaches its maximum at 300 °C, which of various absorption mechanisms at 300 °C are 6.3, 11.6, 4.4, and 14.7 times higher than that at 20 °C corresponding to an optical phonon, impurity, 2PA, and 3PA processes, respectively. These results indicate that it should be possible to regulate the FCA, 2PA, and 3PA processes by changing the deposition temperature, thus making them suitable for applications in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Site-selective time-resolved laser spectroscopy techniques, which provide high spectral resolution at low temperatures (4.2 K and 6.5 K), were used to clarify the formation mechanism, spectral and kinetic properties of the Nd3+ ion single-site optical centers formed in the fluorite-type BaF 2 single crystals doped with Nd3+. This formation occurs by heterovalent substitution of Ba2+ host cations with additional charge compensation by F− anions. To determine the lifetimes of the Stark 4F 3/2 (1) levels of the Nd3+ impurity centers, the fluorescence decay kinetics was measured using the gated photon counting technique. The data from spectroscopic experiments were combined with density functional theory (DFT) calculations to identify and analyze the local structure of Nd3+ cations in the Nd3+ ions doped BaF 2 crystal. Our studies have shown that several types of single-site Nd3+ optical centers can be distinguished in BaF 2 :Nd3+. We confirmed the existence of an optical center with high C 4v site symmetry and a long radiative lifetime of the 4F 3/2 (1) state τ = 14.3 ms. We also describe two other configurations of centers with local structure characterized by low site symmetry of C s , which were identified and described for the first time. The decrease in the tetragonal site symmetry from C 4v to C s was explained by the fact that the Nd3+ dopants, distributed over the equivalent cationic positions of the fluorite-type crystal lattice, coordinate to anionic motifs that essentially differ in the position of the additional charge compensator F−. This structural variability induced in the local coordination environment of the optical center affects its spectroscopic properties through a shift in the energy of the 4F 3/2 (1) Stark level of the Nd3+ ion and results in a different radiative lifetime τ. • Nd3+ ion single-site optical centers in BaF 2 crystals were studied. • DFT analysis showed four configurations of the Nd3+ ion sites in BaF 2. • Local geometries of the Nd3+ ion single-sites in BaF 2 were determined. • The existence of Nd3+ site in BaF 2 with high C 4v site symmetry was confirmed. • Two configurations of the Nd3+ sites with low symmetry of C s were revealed. [ABSTRACT FROM AUTHOR]