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Powders of Ag7(Si1-xGex)S5I (x = 0.2, 0.4, 0.6, 0.8) solid solutions were obtained via ball milling for 30 and 60 min. SEM analysis revealed a relatively narrow particle size distribution, with an average particle size of approximately 150 nm (30 min) and 100 nm (60 min). Phase analysis approves the formation of solid solutions and the absence of any destruction during the ball milling. Dense ceramic disks of Ag7(Si1-xGex)S5I solid solutions were fabricated by cold pressing followed by annealing. The ceramic chemical homogeneity was approved by EDS, and the average crystallite size resulting from the recrystallization process was determined by SEM. The frequency and temperature dependence of the electrical conductivity were studied using the EIS method. It was established that Ag7(Si1-xGex)S5I-based ceramic materials are mixed conductors with a significant predominance of ionic conductivity. The compositional dependence of ionic conductivity and its activation energy is non-monotonous. The highest ionic conductivity is observed for Ag7Si0.8Ge0.2S5I (6.88 × 10−2 S cm−1) and Ag7Si0.2Ge0.8S5I (8.05 × 10−2 S cm−1) ceramics. Also, the impact of the initial particle size of powders, ceramic microstructure, and isovalent Si+4 → Ge+4 cationic substitution on the electrical parameters of Ag7(Si1-xGex)S5I solid solutions is discussed. [ABSTRACT FROM AUTHOR]

Preparation, phase and microstructural analysis, microhardness, electrical conductivity investigation of Ag7Si0.4Ge0.6S5I nanocrystalline powders and corresponding ceramic materials are reported. The Ag7Si0.4Ge0.6S5I microcrystalline powder were grinded in a ball milling (for 30 and 60 min) to an average particle size ∼ 190 and ∼ 110 nm (determined by SEM). The phase homogeneity of the nanocrystalline powders was established by XRD. Ceramics were fabricated by cold pressing (400 MPa) and following sintering (700 °C). Recrystallization process leads to increasing the crystallites size in ceramics to the values of ∼ 2.09 and ∼ 1.72 μm from initial 190 and 110 nm. Ceramics are characterized by low porosity 7.2 ± 2.5% (for 2.09 μm) and 6.9 ± 2.5% (for 1.72 μm) and chemical homogeneity. Microhardness investigation of both ceramics shown a presence of «normal» indentation size effect. The frequency dependences of the total electrical conductivity are characterized by a sharp increase in electrical conductivity with increasing frequency. The corresponding values of ionic (σion), electronic (σel) conductivity, activation energy (Ea) was determined. Established that ionic conductivity of fabricated from ~ 190 nm powder (7.78 × 10−2 S cm–1) is higher than for ~ 110 nm (7.52 × 10−2 S cm–1). A comparison of the electrical parameters (σion, σel, σion/σel, Ea) of the single crystalline and ceramic materials (with different grain sizes) was performed. [ABSTRACT FROM AUTHOR]

Doping of transition metal diborides (TMB2) films with soft metals (Ag, Au, Pt) can extend their application potential to tribological and biomedical fields. Here, a combination of direct current unbalanced magnetron sputtering (DC-UBMS) with high-power pulsed magnetron sputtering (HiPIMS) was used to synthesize silver-doped CrB2+x thin films on unheated substrates. All Ag–CrB2+x thin films were over-stoichiometric with a B/Cr ratio ranging from 2.05 to 2.30 and silver content varying from 3 at.% to 29 at.%. X-ray diffraction demonstrates the amorphous character of the structure in the case of films with silver content ranging from 0 at.% to 8 at.%. A nanocrystalline structure containing a cubic Ag phase is formed in the films with higher silver content. The highest hardness of 26.6 GPa accompanied by the highest value of elastic modulus of 362 GPa was measured in undoped CrB2.3 films. As the silver content in the Ag–CrB2+x thin films increases, the hardness and elastic modulus values gradually decrease to 7.8 GPa and 187 GPa, respectively. The friction properties of CrB2.3 films, expressed by the coefficient of friction against a steel ball of 0.72, are insufficient and limit their use in demanding industrial applications. However, silver doping significantly reduces the friction coefficient when the lowest value of 0.39 is measured in moderately hard Ag–CrB2+x films with an Ag content of 17 at.%. The scratch test shows satisfactory adhesion of films to substrates even without additional heating during deposition. [ABSTRACT FROM AUTHOR]

Cu6PS5I-based thin films were deposited onto silicate glass substrates by magnetron sputtering. With Cu content increase, a red shift of the optical transmission spectra as well as increase of the total electric conductivity are observed. A typical Urbach bundle are revealed, the temperature behaviour of the Urbach absorption edge in thin films are explained by strong electron-phonon interaction. Temperature dependences of the absorption edge energy position and the Urbach energy for thin film are well described in Einstein model. The influence of different type of disordering on the Urbach tail is studied.

Zirconium diboride (ZrB2) represents a promising hard coating material for demanding high-temperature applications and could provide an excellent basis for fine-tuning mechanical properties via the concept of alloying. Here, combining density functional theory and experiments, we investigate the effect of aluminum alloying on thermally induced structure evolution and mechanical properties of α-structured Zr1 − xAlxB2 + Δ. Ab initio calculations predict a strong tendency for spinodal phase separation of hexagonal Zr1 − xAlxB2 solid solution into isostructural binaries. Experimental results confirm predictions of the insolubility of aluminum in the ZrB2 phase when the structure of magnetron co-sputtered Zr0.72Al0.28B2.64 films with an aluminum content of 8 at. % has a nanocomposite character consisting of hexagonal α-ZrB2 nanocolumns surrounded by an amorphous Al-rich tissue phase. The films are structurally stable up to 1100 °C but out-diffusion of Al atoms from boundary regions during annealing was observed. Al alloying causes a significant decrease in hardness when the hardness of the reference as-deposited ZrB2.2 and Zr0.72Al0.28B2.64 is 39 and 23 GPa, respectively. Low hardening effect in ternaries was observed after annealing at 1000 °C when the hardness increased from 23.5 to 26.5 GPa due to the locally increased concentration of point defects at the boundaries of the nanocolumns and Al-rich tissue phases. Young's modulus decrease from 445 (ZrB2.2) to 345 GPa (Zr0.72Al0.28B2.64) indicates a change in the mechanical response of the ternary film toward more ductile behavior. [ABSTRACT FROM AUTHOR]