Search Results (7,780)

Titanium alloys are characterized by insufficient ductility. One of the parameters affecting their ductility is their crystal structure and texture. The present study characterizes the changes in the crystallographic texture of the Ti-3Al-8V-6Cr-4Zr-4Mo alloy in solution-treated and aged conditions on the basis of texture intensity indices and pole figures. Analysis of crystal structure changes was performed before and after tensile testing. The investigated alloy in the solution-treated condition showed a single-phase β-solution structure with a body-centered cubic (BCC) crystal structure. The process of β phase aging affected the result of the tensile test, affecting the parameters of the texture of the β phase. The analysis of the texture intensity indices for each set of planes (hkl) related to the intensity for the plane (110) indicated that the highest texture intensity occurs for β titanium alloy aged at 550 °C both before and after tensile test. After plastic deformation, the largest difference with respect to the benchmark value was observed for the (220) and (310) planes. The least amount of texture intensity occurred after aging at 450 °C. The most varied values of diffraction peak intensity in relation to the benchmark were obtained for the alloy aged at 450 °C for the (310), and (200) and (211) planes, indicating the dominance of the (211) orientation, where an elongation of 10.4% was achieved. For the highest elongation of 14.2%, achieved for the sample solution-treated at 550 °C, the diffraction peak intensities were intermediate with the dominance of peaks from the planes (200) and (310). Full article

The paucity of multi-component compounds containing the non-steroidal anti-inflammatory drug (NSAID) S-(+)-ibuprofen (S-IBU) in combination with other drugs prompted the present study, which describes 1:1 salts of this active pharmaceutical ingredient (API) with the two most widely used antifibrinolytic APIs, namely 6-aminohexanoic acid (aminocaproic acid, ACA) and tranexamic acid (TXA), which are zwitterions in the solid state. Since NSAIDs are known to cause adverse side effects such as gastrointestinal ulceration, the presence of ACA and TXA in the salts with S-(+)-ibuprofen might counter these effects via their ability to prevent excessive bleeding. The salts were prepared by both the liquid-assisted grinding method and co-precipitation and were characterized by X-ray powder diffraction and single-crystal X-ray diffraction, thermal analysis, Fourier transform infrared spectroscopy, and solubility measurements. The X-ray analyses revealed a high degree of isostructurality, both at the level of their respective asymmetric units and in their extended crystal structures, with charge-assisted hydrogen bonds of the type N-H⁺⋅⋅⋅O⁻ and O-H⁺⋅⋅⋅O⁻ featuring prominently. The thermal analysis indicated that both salts had significantly higher thermal stability than S-(+)-ibuprofen. Solubility measurements in a simulated biological medium showed insignificant changes in the solubility of S-(+)-ibuprofen when tested in the form of the salts (S-IBU)⁻(ACA)⁺ and (S-IBU)⁻(TXA)⁺. Full article

Diamond-based transistors have been considered as one of the best choices due to the numerous advantages of diamond. However, difficulty in the growth and fabrication of diamond needs to be addressed. In this paper, high quality diamond film with an atomically flat surface was grown by microwave plasma chemical vapor deposition. High growth rate, as much as 7 μm/h, has been acquired without nitrogen doping, and the root mean square (RMS) of the surface roughness was reduced from 0.92 nm to 0.18 nm by using a pre-etched process. H-terminated diamond MOSFETs were fabricated on a high-quality epitaxial diamond layer, of which the saturated current density was enhanced. The hysteresis of the transfer curve and the shift of the threshold voltage were significantly reduced as well. Full article

Aluminum matrix composites (AMCs) are largely used in defense, maritime, and space applications for their excellent properties. LM5 is used where very high resistance to corrosion from seawater or marine atmospheres is required, for equipment used for the manufacture of foodstuffs, cooking utensils, and chemical plants. Zirconia is preferred over other reinforcements as it shows comparatively great refractory properties, high scratch resistance, and thermal shock resistance. Utilizing the stir casting technique, an attempt was made to produce AMCs of LM5 aluminum alloy strengthened with ZrO₂. The weight percentage of ZrO₂ was changed to 0%, 3%, 6%, and 9%. The specimens were prepared and tested as per ASTM standards to find the density, micro and macro hardness, impact, tensile, and compressive strength. The micrographs and SEM images confirm the uniform distribution of ZrO₂ particles in the aluminum matrix. LM5/9%ZrO₂ AMC has the highest density value of 2.83 g/cm³ and LM5/3%ZrO₂ has the least porosity of 2.55%. LM5/9% ZrO₂ has the highest hardness values of 78 VHN and 72 HRE. LM5/6% ZrO₂ AMC has the highest tensile strength of 220 MPa, compressive strength of 296 MPa, and toughness of 12 J. LM5/6% ZrO₂ AMCs may be used for many structural applications. Full article

Germanium dioxide (GeO₂) is a versatile material with several different crystalline polymorphs and interesting applications in, e.g., optics, microelectronics, and Li-ion batteries. In particular, many of the material’s properties depend on the size of the prepared crystallites, and thus, nanocrystalline GeO₂ is of special interest. Here, GeO₂ nanoparticles are prepared via sol–gel processes by the hydrolysis of Ge isopropoxide (Ge(OCH(CH₃)₂)₄). The precipitated powders are dried at room temperature and annealed in ambient air using temperatures between 500 °C and 1000 °C from 3 to 24 h. The samples were characterized by X-ray diffraction, X-ray absorption fine structure spectroscopy, and scanning electron microscopy, providing the crystalline structures, the phase composition, as well as the morphology and crystallite size of the formed particles and their changes upon heating. According to the structural analysis, the samples are crystalline with a dominant β- (low temperature) quartz phase without any heat treatment directly after drying and increasing contributions of α- (high-temperature modification) quartz and quartz-like GeO₂ structures with increasing temperature and annealing time were found. According to electron microscopy and the X-ray analysis, the particle size ranges from about 40 to 50 nm for the pristine particles and to about 100 nm and more for the annealed materials. Full article

A new mineral, hanauerite, ideally AgHgSI, was found in the oxidation zone of Ag- and Hg-bearing ores at two old, abandoned mines in Rhineland-Palatinate, Germany. In a holotype specimen originating from the Schöne Aussicht Mine, Dernbach, Westerwald, it is associated with plumbogummite–hinsdalite series of minerals and goethite. In cotype from the Friedrichssegen Mine, Bad Ems, it is associated with perroudite, goethite, and quartz. At both localities, hanauerite occurs as a prismatic crystal up to 0.15 mm long and up to 0.02 mm thick. The mineral is yellow, transparent, with an adamantine lustre. It is brittle, and cleavage was not observed. The calculated density values are 6.671 and 6.575 g cm⁻³ for holotype and cotype, respectively. The empirical formulae calculated (from electron microprobe data) based on the sum of all atoms = 4 apfu are Ag_0.95Hg_1.00S_1.01(I_0.83Br_0.19Cl_0.03)_Σ1.05 for holotype and Ag_0.97Hg_0.97S_1.05(I_0.76Br_0.25)_Σ1.01 for cotype. Hanauerite is orthorhombic, space group Pmma; the unit cell parameters (from single-crystal X-ray diffraction data; holotype/cotype) are: a = 9.932(2)/9.9256(8), b = 4.6219(19)/4.6209(2), c = 9.891(4)/9.9006(4) Å, V = 454.0(3)/454.19(5) ų, and Z = 4. The crystal structure was studied on single crystals extracted from both holotype and cotype specimens; R1 = 0.0416 (holotype) and =0.0544 (cotype). In hanauerite, Hg²⁺ cations centre strongly distorted octahedra with two short Hg–S bonds (Hg and S atoms build “crankshaft-type” chains) and four strongly elongated Hg–I bonds. The Hg-centred octahedra are connected via common edges and faces to form corrugated layers; Ag⁺ cations are located between these layers. Hanauerite is named in honour of the German mineral collector Dr. Alfred Hanauer (1912–1988). The common crystal chemical features of mercury sulphohalide minerals are discussed. Full article

We synthesized a series of five novel Mn–salen-based compounds (1a–1c, 2a, 2b) through the reaction between precursor chloride complexes and potassium silver/gold dicyanide. The prepared compounds were structurally and magnetically characterized. Our findings revealed that all the Mn(III) central atoms exhibited an axially elongated coordination polyhedron, leading to the observation of axial magnetic anisotropy as indicated by the negative axial magnetic parameter D, which was determined through fitting the experimental magnetic data and supported by theoretical CASSCF/NEVPT2 calculations. Furthermore, we observed magnetic-exchange interactions only in compounds with a special supramolecular topology involving O–H···O hydrogen-bonded dimers. In these cases, the weak magnetic exchange (J/cm⁻¹ = −0.58(2) in 1b and −0.73(7) in 2b) was mediated by the O–H···O hydrogen bonds. These findings were further supported by BS–DFT calculations, which predicted weak antiferromagnetic exchanges in these complexes and ruled out exchange interactions mediated by diamagnetic cyanido metallo–complex bridges. Additionally, we investigated the observed Ag···π (1b) and Au···Au (2b) interactions using QT–AIM calculations, confirming their non-covalent nature. We compared these results with previously reported Mn–salen-based compounds with metallophilic interactions arising from the presence of the [Ag/Au(CN)₂]⁻ bridging units. Full article

Due to the discoloration properties under different applied voltages, dye-doped polymer-dispersed liquid crystal (PDLC) films are widely used as camouflage nets and invisibility cloaks. However, the range of the discoloration has an intuitive effect on their applications. In this work, we studied the gamut range of PDLC film doped with dyes of red, green, blue, and yellow, with the concentration corresponding to the minimum haze of these dyes. The influence of the applied voltage on the color range of single-layer and double-layer films with different backgrounds was studied. The relationship of the voltage with the color was set from 0 V to 60 V at steps of 5 V, to characterize the discoloration of the PDLC films. The results showed that the films could cover 42.48% of the sRGB gamut and even exceed the range. Full article

The electronic and optical properties of finite GaS nanoribbons are investigated using density functional theory calculations. The effect of size, edge termination, and chemical modification by doping and edge passivation are taken into account. The dynamical stability is confirmed by the positive vibration frequency from infrared spectra; further, the positive binding energies ensure the stable formation of the considered nanoribbons. Accurate control of the energy gap has been achieved. For instance, in armchair nanoribbons, energy gaps ranging from ~ 1 to 4 eV were obtained in varying sizes. Moreover, the energy gap can be increased by up to 5.98 eV through edge passivation with F-atoms or decreased to 0.98 eV through doping with Si-atoms. The density of states shows that the occupied molecular orbitals are dominated by S-atoms orbitals, while unoccupied ones are mostly contributed to by Ga orbitals. Thus, S-atoms will be the electron donor sites, and Ga-atoms will be the electron acceptors in the interactions that the nanoribbons might undergo. The nature of electron–hole interactions in the excited states was investigated using various indices, such as electron–hole overlapping, charge–transfer length, and hole–electron Coulomb attraction energy. The UV-Vis absorption spectra reveal a redshift by increasing the size in the armchair or the zigzag directions. Chemical functionalization shows a significant influence on the absorption spectra, where a redshift or blueshift can be achieved depending on the dopant or the attached element. Full article

To repair or improve the performance of H13 hot working molds through the additive manufacturing process, IN 718 was coated on H13 die steel by high-speed laser cladding followed by an ultrasonic surface rolling process (USRP). The mechanism of ultrasonic surface rolling on the mechanical properties of the coating was studied. After USRP, the coating exhibited severe plastic deformation; the microscopic organization of the surface layer was refined and the particle size was significantly reduced. The violent plastic deformation of the coating caused by USRP improved the dislocation density and the grain boundary density, providing an improved yield strength of the coating and improving the high-temperature wear resistance of the coating. After USRP, the surface hardness of the coating increased by 30%. Compared with the coating without USRP, the wear resistance of the coating greatly improved; the wear rate was reduced by 51% and the wear mechanism of the coating changed from large-area adhesive wear and severe abrasive wear to small-area adhesive wear and slight abrasive wear. The IN 718 coating after USRP had a higher hardness and greater wear resistance, significantly improving the service life of H13 steel. Full article

Trauma orthopaedic surgery was the first domain to use degradable metallic implants made of magnesium alloys since the early 20th century. Unfortunately, the major limitation that consists of rapid degradation and subsequent implant failure, which occur in physiological environments with a pH between 7.4 and 7.6, prevents its widespread application. The biggest challenge in corrosion assay is the choice of the testing medium in order to reproduce more closely in vivo conditions. The current study was focused on two Mg-Zn-Ag alloys (Mg7Zn1Ag and Mg6Zn3Ag) and the Mg1Ca alloy. Dulbecco’s Modified Eagle Medium (DMEM) and Kokubo’s simulated body fluid solution (SBF) were selected as testing mediums and we follow the corrosion evaluation by the corrosion rate and mass loss. Also, the corrosion behaviour was interpreted in correlation with the microstructural features and alloying elements of the experimental magnesium-based alloys revealed by optical microscopy (OM), X-ray diffraction (XRD), and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDX). The experimental results highlight the more corrosive nature of the SBF environment and that a higher percentage of silver (2.5 wt.%) exhibited a better corrosion resistance. We consider that the magnesium alloy Mg6Zn3Ag showed valuable biodegradation characteristics to be considered as raw materials for manufacturing small trauma implants. Full article

This study is aimed at investigating crystals (calcium and magnesium phosphates) formed due the interaction of an inorganic conservation treatment (diammonium hydrogen phosphate—DAP) with carbonatic (calcitic and dolomitic) stones through micro-Raman Spectroscopy. The addressed questions concern (i) the identification of magnesium and calcium phosphate minerals crystallized within dolomitic stone samples with a different degree of conservation state and treated with two different DAP solution molarities and (ii) the distinction of complex calcium phosphate mixtures (hydroxyapatite—HAP and octa calcium phosphate—OCP) crystallized within a calcarenite stone treated with DAP. A statistically relevant number of Raman spectra have been acquired in sample cross sections and curve fitting analysis has been performed for the in-depth interpretation of data. The outcomes indicate that Raman Spectroscopy is an effective alternative method for the identification of poorly crystalline calcium phosphates (not easily detectable with X-ray diffraction), even when scarcely present in mixture with magnesium phosphates. Evidence of the Raman analytical capability and high potential to distinguish HAP and OCP in calcitic stones are also presented and discussed. Full article

Two solvates of estetrol have been isolated and characterized by SCXRD and PXRD as well as by thermal analyses, morphology and spectroscopy. Estetrol monohydrate (Estetrol.H₂O, S.G. P1, Z = 12) contains 12 molecules in its asymmetric unit with very subtle conformational differences with one another but reveals an intricate network made of intermolecular H-bonds established with the neighbour estetrol molecules and with crystallization water. Each molecule of estetrol methanol hemisolvate (Estetrol.0.5CH₃OH, S.G. C2, Z = 4) establishes six O-H…O bonds with six different neighbours and additional H-bonds with methanol. In both structures, estetrol molecules are organized in a head-to-tail arrangement that favours the formation of O-H…O interactions. The increased thermal stability of Estetrol.0.5CH₃OH crystals with respect to Estetrol.H₂O can be correlated to the strengthened network of H-bonds. Full article

In order to improve the overall performance of edge plates such as bulldozer blades, composition and heat treatment processes were optimized on the martensitic wear-resistant steel grade 400 HB. Steel billets were first obtained through smelting in a state of hot rolling, followed by quenching and tempering to obtained wear-resistant steel (HB400). Then, HB400 was subjected to metallographic observation, electron backscatter diffraction (EBSD) testing, and transmission electron microscope (TEM) characterization and property testing. The results showed that HB400 exhibited microstructural refinement, characterized by narrower martensite laths and finer grains. The EBSD results indicated a uniform microstructure with a low content of the residual austenite (0.5%), indicating good hardenability. TEM observation of the martensite matrix revealed the presence of substructures, i.e., numerous dislocations in martensite laths. The average Rockwell hardness (HRC) of HB400 was 46.3, and the average Brinell hardness (HB) was 402. A mechanical properties test demonstrated comprehensive properties, which showed that the ultimate tensile strength and yield strength of HB400 were 1495 MPa and 1345 MPa, respectively, with a relative elongation of 12%. Friction and wear experiments showed that the friction coefficient and wear rate in reciprocating mode decreased by 16.1% and 45.4%, respectively, while in rotating mode, they decreased by 27.6% and 2.1%, respectively, as the load increased from 100N to 300N. According to the wear morphology, the main wear mechanisms were identified as adhesive wear, abrasive wear, and oxidative wear. The lubricating effect of the oxide layer generated by wear was identified as the primary reason for the reduction in the friction coefficient. The relationship between microstructures and properties was discussed based on grain refinement strengthening and dislocation strengthening. Full article

Two-dimensional (2D) van der Waals (vdW) A^IIIB^VI semiconductor materials, such as InSe and GaSe, are of considerable interest due to their potential use in various microelectronics applications. The range of properties of materials of this class can be extended further through the use of quasi-binary alloys of the InSe(Te)-GaSe(Te) type. In this work, we study the effect of compositional and structural disorder in 2D In(Ga)Se(Te) on the band structure and electronic properties using first principles modeling. The results for In(Ga)Se demonstrate a noticeable decrease in the band gap for structures with a random distribution of indium and gallium cations, while for In(Ga)Te with a random cation distribution, metallization occurs. Changes in the compositional arrangement of chalcogens (there can be either the same or different atoms on each side of the vdW gap) lead to pronounced changes in the band gap, but no significant changes in topology are observed. In addition, a significant effect of the distance between the layers on the band gap under compression along the c axis was found for both alloys under study. An important point of our study is that van der Waals gap engineering is a very powerful tool to control the properties of 2D materials and its alloys. Full article