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The synthesis, characterization, and testing of new inorganic compounds as perspective adsorbents or ion exchangers are of significant importance. Magnesium fluoride is a well-known inorganic compound that is affordable and widely used in various scientific and industrial applications. A series of adsorption experiments have been conducted, including investigations of pH range, magnesium fluoride dose weights, initial concentration of the Rare earth elements (REEs) and adsorption time. An outstanding finding regarding magnesium fluoride as an adsorbent is that REEs were separated at pH 1 through ion exchange and at pH 4 through adsorption mechanisms, showing nearly identical uptake of 191 mg/g. Under optimal adsorption conditions, the REEs were adsorbed on magnesium fluoride with an uptake of 302.4 mg. The morphological traits of magnesium fluoride were characterized using energy dispersive spectroscopy (EDS), scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FTIR). Kinetically, the adsorption of REEs on magnesium fluoride aligns with the pseudo-second-order model and exhibits a theoretical loading capacity of 310 mg/g. What’s more, isothermally, the adsorption of REEs corresponds to the Langmuir model and predicts a theoretical uptake of 305 mg/g. Interference studies indicate that magnesium fluoride is a promising adsorbent and exhibits notable selectivity. The study suggested that magnesium fluoride has shown a higher saturation capacity compared to other Group IIA fluorides. From a sustainability perspective, magnesium fluoride has been sourced from the Mediterranean Sea. This approach achieved a REEs separation capacity of 308.7 mg/g after implementing all the optimum sol-gel magnesium fluoride adsorption conditions. Graphical Abstract Highlights Synthesis of an affordable, selective and sustainable sorbent magnesium fluoride (MgF 2 ) for rare earth elements (REEs) capture. The magnesium fluoride separates REEs in the pH range of 1–4 at the same REEs saturation capacity and efficacy, practically, the separation of REEs at pH 1 occurred entirely by ion exchange mechanism, and by adsorption mechanism at pH 4. Magnesium fluoride demonstrates optimal selectivity at pH 1 and exhibits moderate selectivity at pH 4. Magnesium fluoride outperformed other Group 2 fluorides in REEs separation in the following order: MgF 2  > CaF 2  > BaF 2  > SrF 2 . The Mediterranean Sea was utilized as a sustainable magnesium source and effectively separated REEs.

As an emerging platform for high-precision sensing, integrated silicon-waveguide-based cavity optomechanical devices face a critical fabrication challenge in the co-fabrication of silicon-on-insulator (SOI) micromechanical structures and optical waveguides: the silicon oxide (SiO2) layer beneath the waveguides is susceptible to etching during hydrofluoric acid (HF) release of the microstructures, leading to waveguide collapse and significantly reducing production yields. This study proposes a novel selective protection process based on a magnesium fluoride (MgF2) thin film to address the critical challenge of long-range waveguide collapse during hydrofluoric acid (HF) etching. By depositing a MgF2 protective layer over the waveguide regions via optical coating technology, localized protection of specific SiO2 areas during HF etching is achieved. The experimental results demonstrate the successful release of silicon waveguides with lengths of up to 5000 μm and a significant improvement in production yield. This work provides a compatible and efficient strategy for the fabrication of robust photonic–microelectromechanical integrated devices.

Porous MgF 2 antireflective λ/4 films were prepared by sol–gel processing and coated with an additional top layer by electron beam evaporation. Scanning Electron Microscopy was applied to characterize the microstructure of the bilayer assembly. It can be shown that the top layer has a protective effect in terms of abrasion resistance and reduced solubility in water. In a second step the thickness of the two film systems has been matched to achieve optimum antireflection properties. Porous antireflective MgF 2 coatings were prepared by sol–gel processing. On these samples dense MgF 2 films were deposited by evaporation in order to increase the stability of the system. Highlights MgF 2 was evaporated on sol–gel derived porous antireflective MgF 2 coatings. The microstructure of the bilayer assemblies was characterized by scanning electron microscopy (SEM). The evaporated layer provides improved abrasion resistance and reduced water solubility.

Due to difficulties in obtaining monomaterials, intensive research into the properties of ceramic compositions has been undertaken, along with developments to the properties of the compositions. These are not inferior to monomeric structures for a number of basic parameters. Among the different types of ceramics, magnesium fluoride and zinc sulfide occupy a special place due to their unique properties and specific applications. In this paper, we studied functional optoelectronics and modulating technique elements based on the advanced ceramics MgF2 and ZnS. The results of the transmittance spectral parameters and the contact angle estimation as well as an AFM analysis of the studied ceramics, both pure and structured with carbon nanotubes, are presented. We observed that the main characteristics of the studied materials with a surface modified by carbon nanotubes could be significantly changed when an innovative laser-oriented deposition method was applied. This method permitted the CNTs to be deposited in a vertical position on the material surface. The main features of the carbon nanotubes—such as the smaller value of the refractive index, the greater strength between the carbon atoms, and the effective surface—were taken into consideration. The analytical, quantum chemical, and experimental results of the studies of the changes in the basic physical parameters of the selected model of the inorganic matrices of the ceramics are given.

MgF2 films are prepared using plasma-enhanced atomic layer deposition (PEALD). The influence of substrate temperature on the growth behavior, chemical composition, and optical properties of MgF2 films is systematically investigated. The experimental results show that the deposition process transitions through three distinct regimes: an incomplete-reaction regime at 100 °C, a self-limiting ALD window at 125–150 °C, and a chemical vapor deposition (CVD)-like regime above 175 °C. At 100 °C, incomplete surface chemistry yields low growth-per-cycle, carbon incorporation, and an elevated refractive index. Within 125–150 °C, films are near-stoichiometric, smooth, and exhibit a low refractive index ≈ 1.37 ± 0.003 at 550 nm. Above 175 °C, precursor decomposition drives non-self-limiting growth with increased roughness. As an application-level validation, a film grown at 125 °C used as a double-sided antireflection coating on glass increases transmittance from 92 ± 0.1% (bare) to 97.2% ± 0.2% at 550 nm. The average transmittance of 96.4 ± 0.2% over 380–780 nm can be achieved. Overall, this work establishes the relationship between deposition temperature and PEALD-MgF2 film properties and demonstrates precise, low-temperature, non-corrosive deposition suitable for advanced optical antireflection coatings.

A cost effective catalyst is of great importance for consideration of MgH2 as potential hydrogen storage material. In this regard, we investigated the catalytic role of alkaline metal fluoride on the hydrogen storage behavior of MgH2. Samples were synthesized by admixing 5 mol % MgF2 into MgH2 powder using planetary ball mill. Hydrogenation measurements made at 335 °C showed that in comparison to only 70% absorption by pure MgH2, catalyzed material absorbed 92% of theoretical capacity in less than 20 min and desorbed completely in almost the same time. Sorption studies done at lower temperatures revealed that complete absorption at temperature as low as 145 °C is possible. This is due to uniform distribution of MgF2 nano particles within the MgH2 powder. X-ray diffraction patterns also showed the presence of stable MgF2 phase that does not decompose upon hydrogen absorption-desorption. Cyclic measurements done at 310 °C showed negligible loss in the overall storage capacity with cycling. These results reveal that the presence of the chemically inert and stable MgF2 phase is responsible for good reversible characteristic and improved kinetics.

The synthesis of the nanopowders of magnesium oxide and magnesium fluoride during the operation of a repetitive diffuse nanosecond discharge in argon at various pressures was performed. Nanosecond voltage pulses with an amplitude of −70 kV, a rise time of 0.7 ns, and a duration of 0.7 ns were applied across a point-to-plane gap of 2 mm in length. The pulse repetition rate was 60 Hz. The high-voltage pointed electrode was made of magnesium. A diffuse discharge cold plasma was formed under these conditions. Nanoparticles were produced as a result of an explosion of microprotrusions on the surface of the magnesium electrode duo to a high current density. Lines of magnesium atoms and ions were observed in the emission optical spectrum. Under the actions of the gas dynamics processes caused by the plasma channel expansion during the interpulse period, nanoparticles were deposited onto the surface of the grounded plane electrode and the side wall of the gas discharge chamber. The morphology, elemental, and phase composition of the powders were studied using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS).

This work discusses the possibility of decomposing magnesium fluoride by ionized water vapor to form solid magnesium oxide and hydrogen gas in the reaction: MgF2 + H2O → MgO + 2HF. The technology and individual apparatuses of the plasma-chemical installation are described, and the influence of the fractional composition of magnesium fluoride powder on the productivity of the plasma conversion process is considered. To improve the efficiency of the plasma pyrolysis process, a method for making magnesium fluoride briquettes was developed. The completeness of the conversion process of magnesium fluoride to an oxide was evaluated by energy dispersive X-ray spectroscopy in the study of objects in scanning electron microscopy (SEM) and by X-ray diffractometry. It was found that the conversion process of magnesium fluoride to magnesium oxide has a relatively high degree of decomposition of magnesium fluoride fraction ≤75 µm. The use of the proposed processing method makes it possible to obtain pure magnesium oxide as a commercial product and to utilize fluorine-containing industrial waste.

Abstract—An optical scheme is described for a compact focal monochromator with a plano-convex magnesium-fluoride lens for measuring and analyzing transmission spectra of transparent objects in the vacuum ultraviolet spectral range within air transparency bands in the 113—140 nm spectral range. Short distances between the source and detector in the range from 5 to 40 mm allow operation in air, using the presence of bands of mutual partial transmittance of oxygen and water vapor at wavelengths of 114.2, 116.4, 118.5, 121.2, 123.5, and 127.0 nm. Simulated absorption spectra of air spaces of different lengths are presented in the spectral range of interest. Deuterium lamp emission spectra are experimentally measured in the 113–140 nm spectral range after passing through air gaps of different lengths. The monochromator spectral resolution reaching 50 near the magnesium fluoride absorption edge is defined by the joint contribution of the lens dispersion and radiation filtering in the air spectral transmittance bands.

The screening method has been used to investigate the effects of magnesium fluoride, polytetrafluoroethylene, and ammonium hexafluorotitanate additives in a composite propellant on the basis of boron or aluminum dodecaboride as a fuel (37%), ammonium perchlorate as an oxidizer and an active binder on the parameters of propellant combustion. At pressures of 1.2 and 2.4 MPa, propellant combustion rates were measured, samples of condensed combustion products were taken, and burning residue in the form of a carcass was investigated. Using the cerimetric method of chemical analysis of the selected combustion products, incompleteness of propellant combustion was indentified and the efficiency of its energy release was evaluated. It is shown that the addition of small quantities (1%) of the said substances to the propellant makes it possible to control the velocity of its combustion and, in some cases, to raise the efficiency of energy release.