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Ionic substitutions play important role in the modifications of biological apatites. Recently, the attention has been focused on the co-doping effects on functional properties of apatite based biomaterials. In this research work, the dense samples of fluorapatites, Ca10(PO4)6F2 and Ca8MgSr(PO4)6F2, were produced after sintering at 1250°C for 6 h in air. Structural characterization, carried out with XRD, IR, Raman and SEM, confirmed the formation of dense and homogeneous structure with main fluorapatite and small amount of Ca3(PO4)2 phase. The presented results also demonstrate the stability of structural and mechanical properties of fluorapatites after immersion tests in saline and buffer solutions. The durability of mechanical properties and biocompatibility of the Ca10(PO4)6F2 and Ca8MgSr(PO4)6F2 fluorapatites make these materials highly attractive for biomedical application.

Despite considerable progress, high-performing durable catalysts operating under large current densities (i.e., >1000 mA/cm2) are still lacking. To discover platinum group metal-free (PGM-free) electrocatalysts for sustainable energy, our research involves investigating layered topological magnetic materials (semiconducting ferromagnets) as highly efficient electrocatalysts for the hydrogen evolution reaction under high current densities and establishes the novel relations between structure and electrochemical property mechanisms. The materials of interest include transition metal trihalides, i.e., CrCl3, VCl3, and VI3, wherein a structural unit, the layered structure, is formed by Cr (or V) atoms sandwiched between two halides (Cl or I), forming a tri-layer. A few layers of quantum crystals were exfoliated (~50−60 nm), encapsulated with graphene, and electrocatalytic HER tests were conducted in acid (0.5M H2SO4) and alkaline (1M KOH) electrolytes. We find a reasonable HER activity evolved requiring overpotentials in a range of 30–50 mV under 10 mA cm−2 and 400−510 mV (0.5M H2SO4) and 280−500 mV (1M KOH) under −1000 mA cm−2. Likewise, the Tafel slopes range from 27 to 36 mV dec−1 (Volmer–Tafel) and 110 to 190 mV dec−1 (Volmer–Herovsky), implying that these mechanisms work at low and high current densities, respectively. Weak interlayer coupling, spontaneous surface oxidation, the presence of a semi-oxide subsurface (e.g., O–CrCl3), intrinsic Cl (or I) vacancy defects giving rise to in-gap states, electron redistribution (orbital hybridization) affecting the covalency, and sufficiently conductive support interaction lowering the charge transfer resistance endow the optimized adsorption/desorption strength of H* on active sites and favorable electrocatalytic properties. Such behavior is expedited for bi-/tri-layers while exemplifying the critical role of quantum nature electrocatalysts with defect sites for industrial-relevant conditions. [ABSTRACT FROM AUTHOR]

This study focuses on the development and optimization of MoO3 films on commercially available FTO substrates using the pulsed laser deposition (PLD) technique. By carefully selecting deposition conditions and implementing post-treatment procedures, precise control over crystallite orientation relative to the substrate is achieved. Deposition at 450 °C in O2 atmosphere results in random crystallite arrangement, while introducing argon instead of oxygen to the PLD chamber during the initial stage of sputtering exposes the (102) and (011) facets. On the other hand, room temperature deposition leads to the formation of amorphous film, but after appropriate post-annealing treatment, the (00k) facets were exposed. The deposited films are studied using SEM and XRD techniques. Moreover, electrochemical properties of FTO/MoO3 electrodes immersed in 1 M AlCl3 aqueous solution are evaluated using cyclic voltammetry and electrochemical impedance spectroscopy. The results demonstrate that different electrochemical processes are promoted based on the orientation of crystallites. When the (102) and (011) facets are exposed, the Al3+ ions intercalation induced by polarization is facilitated, while the (00k) planes exposure leads to the diminished hydrogen evolution reaction overpotential. [ABSTRACT FROM AUTHOR]

The influence of guest molecules affecting the spin transition characteristics of iron(II) complexes represents a widely discussed topic because it opens the possibility of using this type of materials in many fields of science, especially if the material properties could be tuned in a controlled way. We report an experimental observation of the spin transition in thin films of a 3D Hoffman framework nanocrystalline material Fe(pyrazine)[Pt(CN)4] deposited by nanosecond laser ablation at λ = 1064 nm of its cryo-cooled colloidal suspension in water and water-free organic solvents. For vacuum deposited films (thickness 120 nm), the substantial downshift in temperature, gradual spin transition, and shrinkage of the temperature hysteresis compared to the starting material are ascribed to incomplete removal of water molecules from the porous network and partial destruction of the crystalline site caused by laser heating. The destructive effect of laser irradiation occurring in vacuum conditions was not observed for deposition conducted in N2 at atmospheric pressure. In this case, thin films reproducing properties of the reference material with transition temperature near 276 K and 12 K wide hysteresis were obtained. In addition, the changes in the spin switching characteristics associated with the exchange of guest molecules in the SCO crystal lattice were observed using a water-free solvent as a matrix for the laser based thin film deposition. The observed laser induced host–guest exchange indicates on the possibility of selective modification of thin layers of SCO materials to obtain their desired characteristics. [ABSTRACT FROM AUTHOR]

Few‐layer black phosphorus (FLBP) is a 2D material that gains worldwide interest for its possible applications, mainly in electronics and optoelectronics. However, as FLBP is prone to a degradation process under environmental conditions, there is a need for a monitoring method allowing investigation of its surface quality. Among many techniques, optoelectronic ones have unique advantages of fast response, non‐contact, and non‐invasive operation. In this paper, a photonic method is presented for this purpose with a focus on the earliest stages of the degradation process. Measurements are performed using a fiber‐optic interferometer working at the wavelength of 1310 nm. Series of material characterization measurements, including scanning electron microscopy, X‐ray photoelectron spectroscopy, and Raman spectroscopy investigations are performed to examine the FLBP using a well‐established methodology. Two samples—with liquid exfoliated FLBP and with layers of supernatant—prepared in two different production processes are investigated over 3 h. A detailed presentation of the degradation process is provided. The results prove that the surface monitoring of FLBP is possible by registering optical signal changes correlated with the changes in optical parameters caused by the proceeding degradation process. [ABSTRACT FROM AUTHOR]

In this work, the fabrication of [Fe(pz)Pt(CN)4] (pz = pyrazine) thin films by means of matrix‐assisted pulsed laser evaporation (MAPLE) was investigated. As starting material, a cryogenically cooled suspension of nanocrystalline [Fe(pz)Pt(CN)4] (0.35wt.‐%) in a mixture of 1,1‐dichloroethane and polyethylene glycol (PEG) was used. Films of a thickness up to 150–200 nm were deposited on Si substrates by laser ablation at λ = 1064 nm of the cryogenically cooled material. PEG impregnated films exhibit a cooperative first‐order hysteretic spin crossover behavior around 155 K as detected by Raman spectroscopy. Most interestingly, deposition of a crystalline material was achieved through MAPLE deposition. [ABSTRACT FROM AUTHOR]

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The main subject of this study are molecular structures and optical properties of boron-doped diamond films with [B]/[C]ppm ratio between 1000 and 10 000, fabricated in two molar ratios of CH4-H2mixture (1 % and 4 %). Boron-doped diamond (BDD) film on the fused silica was presented as a conductive coating for optical and electronic purposes. The scanning electron microscopy images showed homogenous and polycrystalline surface morphology. The Raman spectroscopy confirmed the growth of sp3diamond phase and sp2carbon phase, both regular and amorphous, on the grain boundaries, as well as the efficiency of boron doping. The sp3/sp2ratio was calculated using the Raman spectra deconvolution method. A high refractive index (in a range of 2.0 to 2.4 at λ= 550 nm) was achieved for BDD films deposited at 700 °C. The values of extinction coefficient were below 1.4 at λ= 550 nm, indicating low absorption of the film [ABSTRACT FROM AUTHOR]

This paper presents a newly developed dermatological laser (with a central wavelength 975 nm) for application in therapies requiring deep penetration of tissue, e.g., cutaneous (dermal) neurofibroma (von Recklinghausen disease) and hemangiomas. This laser can work either in pulses or continues wave mode. Laser radiation is transmitted toward the application region by optical fiber with a diameter of 0.6 mm. The compact design of the laser facilitates its transport and increases the comfort of use. [ABSTRACT FROM AUTHOR]

Carbon nanotubes due to their catalytic properties are a promising alternative to platinum counter electrodes (CE) for dye-sensitized solar cells (DSSC). In this study, counter electrodes were made from double-walled carbon nanotube (DWCNT) ink using the spray printing technique and afterwards they were thermally treated at temperatures ranging from 120 to 300 °C. Morphology and structure was studied using scanning electron microscopy and Raman spectroscopy. DSSCs were constructed from titanium-dioxide photoanodes and DWCNT counter electrodes cured at various temperatures. The current-voltage characteristics of DSSCs and their impedance spectra recorded under illumination have been studied and compared. The photoconversion efficiency (PCE) of the solar cell reached a maximum value of 4.59% when the carbon layer was thermally treated at 300 °C and is 16% higher than that registered for devices with a standard platinum counter electrode. [ABSTRACT FROM AUTHOR]

Relatively high temperatures even up to 500 °C are required to obtain bismuth vanadate (BiVO4) films with the scheelite monoclinic (s-m) structure that shows the highest photocatalytic activity. This requirement limits the possible choice of substrates. Moreover, high quality thin layers of crystalline BiVO4 cannot be prepared with current methods. In this study a light-induced crystallization approach is presented, which is a step toward preparation and patterning of BiVO4 (s-m) films for applications on plastic substrates. Thin films of amorphous BiVO4 are prepared by pulsed laser deposition. The possibility of using green (514.7 nm) laser illumination for crystallization of BiVO4 is investigated. The laser-induced phase transition is tracked using Raman spectroscopy. The results are compared with those obtained from thermally annealed samples, crystalline structure of which is confirmed by measuring X-ray diffraction. The homogeneity and quality of crystallization are verified using micro-Raman spectroscopy imaging, while time-dependent experiments reveal the crystallization rate. The conductivity of the crystallized region is investigated using conductive atomic force microscopy. A strong increase in the conductivity is found in the patterned regions. Experimental results demonstrate the possibility of using the laser-induced crystallization of BiVO4 to prepare patterns of improved conductivity and semiconducting properties in comparison to amorphous surroundings. [ABSTRACT FROM AUTHOR]