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Aluminum garnets display exceptional adaptability in incorporating mismatching elements, thereby facilitating the synthesis of novel materials with tailored properties. This study explored Ce3+-doped Tb3Al5−xScxO12 crystals (where x ranges from 0.5 to 3.0), revealing a novel approach to control luminescence and photoconversion through atomic size mismatch engineering. Raman spectroscopy confirmed the coexistence of garnet and perovskite phases, with Sc substitution significantly influencing the garnet lattice and induced A1g mode softening up to Sc concentration x = 2.0. The Sc atoms controlled sub-eutectic inclusion formation, creating efficient light scattering centers and unveiling a compositional threshold for octahedral site saturation. This modulation enabled the control of energy transfer dynamics between Ce3+ and Tb3+ ions, enhancing luminescence and mitigating quenching. The Sc admixing process regulated luminous efficacy (LE), color rendering index (CRI), and correlated color temperature (CCT), with adjustments in CRI from 68 to 84 and CCT from 3545 K to 12,958 K. The Ce3+-doped Tb3Al5−xScxO12 crystal (where x = 2.0) achieved the highest LE of 114.6 lm/W and emitted light at a CCT of 4942 K, similar to daylight white. This approach enables the design and development of functional materials with tailored optical properties applicable to lighting technology, persistent phosphors, scintillators, and storage phosphors. [ABSTRACT FROM AUTHOR]

The Y 2-x Te 4 O 11 (x = 0.1, 0.5, 1.0, 2.0 and 5.0 at%) microcrystalline powders were successfully synthesized by a conventional solid state reaction method. Optical absorption (300 K) and fluorescence spectra (300 K) as well as fluorescence decay curves (300 K) of the emitting levels of Tm 3+ ion in Y 2 Te 4 O 11 powders are presented and analyzed in details. The Judd-Ofelt theory was applied to analyze experimental data for the quantitative determination of phenomenological Ω λ ( λ  = 2, 4, 6) parameters, radiative transition probabilities ( A ), branching ratios ( β ) of luminescence and radiative lifetimes ( τ rad ) of the 1 D 2 , 1 G 4 , 3 H 4 and 3 F 4 levels. The observed non-exponential decays nature and concentration quenching of the 1 G 4 and 3 H 4 states have been attributed to cross-relaxation processes and this phenomena has been analyzed by Inokuti-Hirayama model. The stimulated emission cross-section for the 3 F 4 → 3 H 6 transition equals to 1.12 × 10 −20 cm 2 at 1809 nm was calculated using the Füchtbauer-Ladenburg method and compared with the corresponding values of other Tm 3+ -doped laser hosts. From obtained results, follow that the Tm 3+ :Y 2 Te 4 O 11 is a potential candidate for a solid-state laser host operating at 1.8 µm. [ABSTRACT FROM AUTHOR]

In this paper, some spectroscopic properties of Y 2 Te 4 O 11 microcrystalline powders, doped with Nd 3+ ions are presented. The samples were successfully synthesized by the solid state reaction method. Absorption (300 K) and fluorescence (at 77 and 300 K) spectra as well as the fluorescence decay curves (300 K) of the 4 F 3/2 state are presented and analyzed. The phenomenological Ω λ (λ=2, 4, 6) Judd-Ofelt parameters were evaluated in order to determine radiative probabilities ( A ), branching ratios ( β ), the radiative lifetime ( τ R ) of the 4 F 3/2 level and the stimulated emission cross-section ( σ em ) for the 4 F 3/2 → 4 I J/2 (J=9 and 11) transitions of the Nd 3+ ion. The fluorescence decay curves were single exponential for 0.01–5.0 at% of Nd 3+ and became evidently non-exponential for higher Nd 3+ ion concentration. With increasing activator concentration from 0.01 to 10.0 at%, the experimental lifetime of the emitting level decreases from 95 to 33 μs. The non-exponential fluorescence decay curve has been fitted by the Yokota-Tanimoto model, indicating that the energy migration process via a diffusion limited relaxation, plays a important role in the depopulation of the 4 F 3/2 level of Nd 3+ ions doped in the Y 2 Te 4 O 11 microcrystalline powder. The calculated absorption value (1.135×10 –19 cm 2 at 807.5 nm) of the 4 I 9/2 → 4 F 5/2 transition as well as the value of the stimulated emission cross-section (1.196×10 –19 cm 2 at 1063.5 nm) for that of 4 F 3/2 → 4 I 11/2 were compared with the corresponding values of other laser hosts. For the first time a very high σ em value of the 4 F 3/2 → 4 I 11/2 transition for TeO 2 -based compounds, has been observed. From the presented spectroscopic properties follows that the Nd 3+ :Y 2 Te 4 O 11 powder is a potential candidate for a random laser host, operating at 1.06 μm. [ABSTRACT FROM AUTHOR]

• BiVO 4 :Tm3+ sub-micro powders were obtained in two polymorphic crystal structures. • The crystal structure of BiVO 4 :Tm3+ depends on the pH value and the temperature. • The bandgap value of BiVO 4 :Tm3+ changes with the phase transition and the grain size. • The emission intensity is four times higher for the I2/b than for the I4 1 /amd phase. • No energy transfer from the host to Tm3+ ions was observed at room temperature. Microwave-assisted hydrothermal method was used to synthesise single phase sub-microcrystalline BiVO 4 :Tm3+ powders with two polymorphic crystal structures – tetragonal zircon-type phase (I4 1 /amd) or monoclinic fergusonite-type phase (I2/b). A single tetragonal phase of BiVO 4 :Tm3+ was obtained at alkaline pH and it was maintained after annealing up to 400°C, while a single monoclinic phase at acidic pH and in the annealing temperature range of 600-900°C. The structural properties of both phases were correlated with their optical properties, such as the energy gap and luminescent properties. It was observed that the crystal structure and the decreasing the crystallites size changes the bandgap value for BiVO 4 :Tm3+. The NIR luminescence of Tm3+ ions analysed for both structural phases of the samples with the smallest crystallites sizes showed that the emission intensity is higher for the monoclinic phase than for the tetragonal phase. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, the optical properties of Y 2 Te 4 O 11 microcrystalline powders doped with Dy 3+ ions, ranging between 0.01 and 5.0 at%, are reported. The powders were successfully synthesized by the solid state reaction method. Absorption (300 K), excitation (300 K) and fluorescence spectra (at 11.6 and 300 K) as well as fluorescence decay curves recorded at room temperature are presented and analyzed in details. Oscillator strengths, phenomenological Ω λ ( λ =2, 4, 6) Judd-Ofelt parameters, radiative transition probabilities, branching ratios, the radiative lifetime of the 4 F 9/2 level as well as the stimulated emission cross-section for the 4 F 9/2 → 6 H 13/2 transition have been determined. The observed non-exponential decay nature and concentration quenching of the 4 F 9/2 emitting level of the Dy 3+ ion, have been attributed to cross-relaxation processes. The high value of the stimulated emission cross-section for the 4 F 9/2 → 6 H 13/2 transition at 576.6 nm, equal to 0.756×10 −20 cm 2 , indicates that Y 2 Te 4 O 11 activated by trivalent dysprosium ions is an attractive candidate for a solid-sate laser. [ABSTRACT FROM AUTHOR]

Among a wide variety of solid state materials, alkali lanthanide double phosphates are the subject of extensive spectroscopic investigations for their application as laser active materials. The edge of absorption in this compound is at rather high energies, which makes them suitable as efficient host for luminescent materials. Spectroscopic properties of Sm 3+ -doped K 3 Y(PO 4 ) 2 are reported basing on the high resolution absorption and emission spectra for various temperatures mainly at 4, 10, and 293 K from UV to IR range. The effects of concentration and temperature on intensities and shape of the observed bands were studied. Radiative transition probabilities were calculated from absorption spectra and Judd–Ofelt parameters evaluated. The excited state dynamics will be discussed based on the decay time measurement. [ABSTRACT FROM AUTHOR]

Spectroscopic properties of Sm 3+ -doped Y 2 Te 4 O 11 micro-crystals were studied in the 6000–18,500 cm −1 spectral range. Vibrational, electronic absorption, fluorescence and excitation spectra as well as fluorescence dynamics of the Sm 3+ -doped title micro-crystals are presented and analyzed in detail. A Judd–Ofelt intensity analysis of the absorption spectrum at 300 K has been applied for determination of Ω λ parameters which in turn have been used for calculations of the radiative transition probability factor ( A ), the fluorescence branching ratios ( β ), the natural (radiative) lifetime of the 4 G(4) 5/2 level of Sm 3+ and the emission cross-section ( σ em ). An analysis of the non-radiative decay was based on the cross-relaxation mechanisms. The achieved results indicate that the investigated samples are potentially applicable as a 605 and 652 nm laser host as well as an orange phosphor. [ABSTRACT FROM AUTHOR]

In this study, the SiO 2 – CaO (SC) and SiO 2 – CaO – P 2 O 5 (SCP) glass powders doped with 0.3 mol% of Tm3+ and 4 mol% of Yb3+ ions were prepared by the sol–gel method. The samples were immersed for four weeks in a simulated physiological environment (Dulbecco's phosphate-buffered saline, DPBS) to investigate the bioactivity of the glasses. Their structure, morphology, and spectroscopic properties were investigated in the function of immersion time. X-ray diffractograms and infrared spectra showed that after incubation in DPBS, the hydroxyapatite starts to build up after 1–3 days. The energy dispersive X-ray spectroscopy analysis indicated the dynamics of ion exchange resulting from the biomineralization process in the glasses. Moreover, the upconversion emission spectra of Tm3+ were measured for all samples under 980 nm excitation wavelength in resonance with the 2F 7/2 → 2F 5/2 absorption of Yb3+. It was observed that the upconversion luminescence continuously decreased and the decay times shorten slightly after the immersion in the buffer. In vitro cytotoxicity assays revealed that the SC glass was biocompatible for all tested cell lines (human chondrocytes, osteoblasts, and fibrosarcoma). However, the SCP powder showed an inhibitory effect on human chondrocyte and fibrosarcoma cells in small concentrations and fibrosarcoma cells in high concentrations. [ABSTRACT FROM AUTHOR]

Abstract: Single crystals of α-Sm3+:Na3Y(VO4)2 have been grown by the flux growth method. The absorption (300K) fluorescence (4.2 and 300K) and excitation (7 and 300K) spectra as well as the fluorescence dynamics of the Sm3+-doped title crystals are presented and analyzed in detail. The energy transfer between Sm3+–Sm3+ as well as from VO4 3− to Sm3+ were studied in detail. A Judd–Ofelt intensity analysis of the absorption (300K) spectrum has been applied for determination of Ω λ parameters which in turn have been used in calculation of the radiative transition probability factor (A), fluorescence branching ratios (β), natural (radiative) lifetime of the 4G(4)5/2 level of Sm3+ and emission cross-section (σ em ). For the first time very large lifetimes of the Sm3+ fluorescence level have been observed. [Copyright &y& Elsevier]

Half-Heusler (HH) phase TmNiSb was obtained by arc-melting combined with high-pressure high-temperature sintering in conditions: p = 5.5 GPa, T HPHT = 20, 250, 500, 750, and 1000 ∘ C. Within pressing temperatures 20–750 ∘ C the samples maintained HH structure, however, we observed intrinsic phase separation. The material divided into three phases: stoichiometric TmNiSb, nickel-deficient phase TmNi 1 - x Sb, and thulium-rich phase Tm(NiSb) 1 - y . For TmNiSb sample sintered at 1000 ∘ C, we report structural transition to LiGaGe-type structure (P 6 3 mc, a = 4.367(3) Å, c = 7.138(7) Å). Interpretation of the transition is supported by X-ray powder diffraction, electron back-scattered diffraction, ab-initio calculations of Gibbs energy and phonon dispersion relations. Electrical resistivity measured for HH samples with phase separation shown non-degenerate behavior. Obtained energy gaps for HH samples were narrow (≤ 260 meV), while the average hole effective masses in range 0.8–2.5 m e . TmNiSb sample pressed at 750 ∘ C achieved the biggest power factor among the series, 13 μ WK - 2 cm - 1 , which proves that the intrinsic phase separation is not detrimental for the electronic transport. [ABSTRACT FROM AUTHOR]

This study provided the first in-depth investigation of the effects of large dopant incompatibility (Pr3+ and La3+ ions) on the small host lattice element (Lu3+) in Lu 3 Al 5 O 12 (LuAG) single crystal. The growth of such complex crystals from the melt presented many challenges. By engineering the ionic radius ratio of RE- and M-site cations, a single-crystal phase stabilized by configurational entropy was achieved. This investigation elucidated the crystallization behavior of configurationally disordered rare-earth aluminum garnet oxide (Lu 1−x−y Pr x La y) 3 Al 5 O 12 from the melt and characterized its functional properties, including microstructural, optical, photoluminescence, and scintillation properties, between 5 and 300 K. Relaxation of the imposed strain energy led to local perturbations and destabilization of the garnet structure. Multielemental EDS mapping, micro-Raman spectroscopy, and thermoluminescence revealed the mechanism by which atomic size mismatch drove a smooth transition from the garnet to the perovskite phase in high entropy garnets. The optical, photoluminescence, and scintillation measurements provided fundamental insights into property changes driven by incompatibility doping. Standard and modified Judd-Ofelt theory analysis of absorption spectra determined the phenomenological Judd-Ofelt parameters Ω λ and radiative lifetimes. Atomic size mismatch engineering offers a promising approach to overcoming the limitations of conventional eutectic synthesis methods. • Perovskite inclusions, driven by atomic size mismatch, extend from rim to core. • Controlled incompatible La3+,Pr3+ codoping in LuAG modify functional properties. • Scintillation light yield improved up to 30% in La3+ codoped LuAG:Pr crystals. • (La,Pr)AlO 3 perovskite forms due to size mismatch of La3+ and Pr3+ with Lu3+. • Lattice disorder affects the intensity ratio of Pr³⁺ 5d→4 f and 4 f→4 f emissions. [ABSTRACT FROM AUTHOR]

Looking for upconverting biocompatible nanoparticles, we have prepared by the sol–gel method, silica–calcia glass nanopowders doped with different concentration of Tm3+ and Yb3+ ions (Tm3+ from 0.15 mol% up to 0.5 mol% and Yb3+ from 1 mol% up to 4 mol%) and characterized their structure, morphology, and optical properties. X-ray diffraction patterns indicated an amorphous phase of the silica-based glass with partial crystallization of samples with a higher content of lanthanides ions. Transmission electron microscopy images showed that the average size of particles decreased with increasing lanthanides content. The upconversion (UC) emission spectra and fluorescence lifetimes were registered under near infrared excitation (980 nm) at room temperature to study the energy transfer between Yb3+ and Tm3+ at various active ions concentrations. Characteristic emission bands of Tm3+ ions in the range of 350 nm to 850 nm were observed. To understand the mechanism of Yb3+–Tm3+ UC energy transfer in the SiO2–CaO powders, the kinetics of luminescence decays were studied. [ABSTRACT FROM AUTHOR]

Silver phosphate and its composites have been attracting extensive interest as photocatalysts potentially effective against pathogenic microorganisms. The purpose of the present study was to investigate the mechanism of bactericidal action on cells of opportunistic pathogens. The Ag3PO4/P25 (AGP/P25) and Ag3PO4/HA (HA/AGP) powders were prepared via a co-precipitation method. Thereafter, their antimicrobial properties against Enterococcus faecalis, Staphylococcus epidermidis, and Staphylococcus aureus (clinical and reference strains) were analyzed in the dark and after exposure to visible light (VIS). The mechanism leading to cell death was investigated by the leakage of metabolites and potassium ions, oxidative stress, and ROS production. Morphological changes of the bacterial cells were visualized by transmission electron microscopy (TEM) and scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy (SEM EDS) analysis. It has been shown that Ag3PO4-based composites are highly effective agents that can eradicate 100% of bacterial populations during the 60 min photocatalytic inactivation. Their action is mainly due to the production of hydroxyl radicals and photogenerated holes which lead to oxidative stress in cells. The strong affinity to the bacterial cell wall, as well as the well-known biocidal properties of silver itself, increase undoubtedly the antimicrobial potential of the Ag3PO4-based composites. [ABSTRACT FROM AUTHOR]

In this study, graphene flakes were obtained using an electrolytic method and characterized using X-ray diffraction (XRD), Raman and FTIR spectroscopy, scanning and transmission electron microscopy (SEM/TEM). Graphene-based composites with varying concentrations of 0.5%, 1% and 3% by weight were prepared with acrylic paint, enamel and varnish matrices. The mechanical properties were evaluated using micro-hardness testing, while wettability and antimicrobial activity against three pathogens (Staphylococcus aureus 33591, Pseudomonas aeruginosa 15442, Candida albicans 10231) were also examined. The results indicate that the addition of graphene flakes significantly enhances both the mechanical and antimicrobial properties of the coatings. [ABSTRACT FROM AUTHOR]

Four highly bioactive glasses in a binary SiO2–CaO system are prepared following a sol−gel method using Ca(OH)2 as a calcium precursor. In the synthesis of glass according to the modified Stöber method, Ca(OH)2 suspended in polyethylene glycol allows the elimination of the presence of calcite and the increase of ammonia concentration causes formation of spherical particles with different sizes in the range of 26–266 nm. The relation among the size and properties, including bioactivity, of the glass particles is evaluated. New glasses that vary in composition (10–25 wt% CaO), porosity (15–113 m2 g−1), and hydroxyl groups content greatly enhance the formation process of hydroxyapatite (HA) in simulated physiological fluids. For all glasses, superior apatite‐mineralization ability in time as short as 2 h in the physiological‐like buffer is achieved, thus exceeding the bioactivity of the known bioactive glasses, including 45S5 glass (Bioglass). The assessment of the safety and toxicity profile of the obtained glasses is verified in a wide range of concentrations (1–1000 µg mL−1) against human dermal fibroblasts and MC3T3 mouse osteoblast precursors, but also to human erythrocytes by determining hemocompatibility. Two glasses of different sizes, 73 and 266 nm, are promising and warrant further research. [ABSTRACT FROM AUTHOR]

Catalytic combustion of hazardous particulate matter (soot) generated by automobile engines is a primary method of their elimination. Ruthenium-based catalysts are a promising alternative for traditional noble metal (Pt, Pd) based systems; however, their relatively poor thermal stability hinders wide applications. In this study, we synthesized a novel, highly active, and stable catalyst for soot oxidation containing bimetallic RuRe nanoparticles supported on TiO2. The RuRe NPs were synthesized by colloidal, microwave-assisted polyol method and deposited on rutile or anatase TiO2. The effect of rhenium content and the nature of TiO2 support on the performance of RuRe nanoparticles (NPs) in the soot oxidation under air atmosphere was investigated. Bimetallic RuRe/TiO2 nanocatalysts exhibited higher activity in the soot oxidation than Ru/TiO2 systems, and the rutile supported 2 wt% Ru–0.4 wt% Re nanocatalyst (Ru/Re atomic ratio of 9:1) showed the best catalytic performance (T50 = 340 °C and T90 < 400 °C). All studied nanocatalysts were stable under reaction conditions in the consecutive catalytic tests. The exceptional catalytic performance of bimetallic RuRe NPs is explained by the synergy effect between ruthenium, rhenium, and TiO2. [ABSTRACT FROM AUTHOR]

We report on the magnetocaloric and thermoelectric properties of CeCrGe3. The compound crystallizes in the BaNiO3-type crystal structure (space group P63/mmc, no. 194, hP10) and undergoes paramagnetic to ferromagnetic phase transition at 70 K, close to the temperature of nitrogen condensation. The transition is found to be second order in nature as evidenced from the Arrott plot analysis. The reversible magnetocaloric effect was observed at low temperature with the magnetic entropy change reaching ΔSm = −2.2 J/(kg K) around 70 K in a magnetic field change of 5 T, with the relative cooling power of RCP = 57 J/kg and the adiabatic temperature change of ΔTad = 0.8 K. The electrical resistivity of CeCrGe3 shows a metalliclike behavior up to 900 K. The Seebeck coefficient remains positive from 2 K up to 900 K and reveals a broad maximum with Smax = 18 μV/K at 300 K. The thermal conductivity near room temperature is of the order of 5.3 W/(m K), resulting in a small value of thermoelectric figure of merit ZT = 0.005. [ABSTRACT FROM AUTHOR]

Ammonia presents a promising hydrogen source and energy carrier for mobile and stationary applications. The development of new and cheaper catalysts for ammonia synthesis is thus of great importance in improving the efficiency of the Haber-Bosch process. Here we report the investigation of ammonia synthesis on cobalt catalysts supported on magnesium–lanthanum mixed oxides with varying Mg/La molar ratios. Our studies revealed that the catalyst's activity is tuneable by varying the support composition, allowing an adjustment of the surface adsorption properties. Owing to the increased basicity of the support and weaker interactions between cobalt and hydrogen atoms, the catalyst supported on mixed MgO–La 2 O 3 oxide with Mg/La molar ratio of 7 demonstrated the highest activity and stability for ammonia synthesis as compared to other reported cobalt catalysts. [Display omitted] • Cobalt catalysts supported on MgO–La 2 O 3 mixed oxides for ammonia synthesis. • Dependence of the surface basicity on the performance of the cobalt catalysts. • Tuning the surface adsorption properties by varying the support composition. [ABSTRACT FROM AUTHOR]

The binding of hydrogen with nitrogen in the ammonia molecule has enormous potential as a hydrogen storage method. The development of efficient ammonia synthesis catalysts with high activity and stability is essential for this reaction. In this study, a series of MgO–Ln 2 O 3 (Ln = La, Nd, Eu) mixed oxides was designed and applied as the support of cobalt catalysts. The tuning of the support composition by selecting lanthanide elements differing in electronegativity led to changes in the physicochemical properties of the catalysts, such as the active phase dispersion, accessibility of active sites for hydrogen, surface density of basic sites. The Co/MgO–Nd 2 O 3 catalyst showed better activity than other studied catalysts in NH 3 synthesis reaction at 470 °C, 6.3 MPa. Its excellent performance is ascribed to the increased density of medium basic sites and the enhancement of electron-donating ability. [Display omitted] • Ammonia synthesis over Co catalysts supported on MgO–Ln 2 O 3 (Ln = La, Nd, Eu) composites. • Variable basic sites and tunable basicity of MgO–Ln 2 O 3 mixed oxides. • A strong influence of support basicity on properties of Co/MgO–Ln 2 O 3 catalysts. • The highest activity and stability of Co supported on MgO–Nd 2 O 3 catalyst. [ABSTRACT FROM AUTHOR]

Amyloid fibrils are widely studied both as target in conformational disorders and as basis for the development of protein-based functional materials. The three Zr phthalocyanines bearing dehydroacetic acid residue (PcZr(L1)2) and its condensed derivatives (PcZr(L2)2 and PcZr(L3)2) as out-of-plane ligands were synthesized and their influence on insulin fibril formation was studied by amyloid-sensitive fluorescent dye based assay, scanning electron microscopy, fluorescent and absorption spectroscopies. The presence of Zr phthalocyanines was shown to modify the fibril formation. The morphology of fibrils formed in the presence of the Zr phthalocyanines differs from that of free insulin and depends on the structure of out-of-plane ligands. It is shown that free insulin mostly forms fibril clusters with the length of about 0.3–2.1 μm. The presence of Zr phthalocyanines leads to the formation of individual 0.4–2.8 μm-long fibrils with a reduced tendency to lateral aggregation and cluster formation (PcZr(L1)2), shorter 0.2–1.5 μm-long fibrils with the tendency to lateral aggregation without clusters (PcZr(L2)2), and fibril-like 0.2–1.0 μm-long structures (PcZr(L3)2). The strongest influence on fibrils morphology made by PcZr(L3)2 could be explained by the additional stacking of phenyl moiety of the ligand with aromatic amino acids in protein. The evidences of binding of studied Zr phthalocyanines to mature fibrils were shown by absorption spectroscopy (for PcZr(L1)2 and PcZr(L2)2) and fluorescent spectroscopy (for PcZr(L3)2). These complexes could be potentially used as external tools allowing the development of functional materials on protein fibrils basis. [ABSTRACT FROM AUTHOR]

Here, we report superconducting Mg11B 2 wires made by using the internal Mg diffusion technique with isotopic amorphous nano boron (11B) as the precursor material. We show the influence of annealing temperature and isostatic pressure of 0.1 MPa and 1.1 GPa on Mg diffusion into 11B layer, microstructure of superconducting filament, critical current density (J c) at 20 K and 25 K, critical temperature (T c) and irreversible magnetic induction (B irr) in mono (single-core) - and multi-filament Mg11B 2 wires. Our research shows that thermal treatment at 700 °C and 0.1 MPa for 60 min yields a superconducting phase with low T c , B irr and J c in single-core Mg11B 2 wire. A higher annealing temperature (740 °C and 0.1 MPa for 60 min) significantly accelerates the diffusion of Mg into the 11B layer and increases the T c , B irr and J c. However, the distribution of Mg in 11B layer is very heterogeneous (places with high and low Mg concentration). This leads to heterogeneity in the superconducting material and inhomogeneous T c , B irr and J c. Further studies showed that higher annealing temperatures at 770 °C and 800 °C significantly accelerates the diffusion of Mg into the 11B layer and leads to the increase of T c , B irr and J c in single-core Mg11B 2 wire. In single-core wire annealing treatment under isostatic pressure of 1.1 GPa for 60 min at temperature of 800 °C it causes Mg penetrates into the 11B layer very heterogeneously and large amount of 11B remains unreacted. However, the same heat treatment at 800 °C and 1.1 GPa for 60 min in multi-filament wires leads to a complete Mg synthesis reaction with the 11B layer. This leads to increase B irr and J c. This work shows that the formation and accumulation of pinning centers is essential to further increase J c in Mg11B 2 wires. [Display omitted] • The Mg diffusion in IMD MgB 2 wires with nano isotopic boron (11B) is much slower than in IMD MgB 2 wires with nano boron. • Annealing temperature 770 °C and 0.1 MPa leads to complete synthesis reaction of Mg with nano 11B in IMD MgB 2 wires. • Thermal treatment under pressure of 1.1 GPa slows down the diffusion of Mg to nano 11B in single core IMD MgB 2 wires. • Thermal treatment under of 1.1 GPa significantly accelerates diffusion of Mg to nano 11B in multi-filament IMD MgB 2 wires. • Thermal treatment at 800 °C under low and high isostatic pressures decrease the density of the pining centers. [ABSTRACT FROM AUTHOR]

• Mg2+ codoping effect on the atoms segregation in GAGG:Ce single crystal studied. • The formation of defects in Mg2+ and Ce3+ codoped GAGG crystals discussed. • The luminescence quenching mechanism in Mg2+ codoped proposed. • The charge compensation mechanism discussed. • Mg2+ codoping influence on the scintillation and luminescence properties investigated. The undoped, Mg2+ doped, Ce3+ doped as well as Mg2+:Ce3+ codoped Gd 3 Al 2 Ga 3 O 12 crystals were grown from the melt by the micro-pulling down method. Ce3+ and Mg2+ ions were codoped in a wide concentration range. A study of Mg2+ ion concentration effect on the luminescence and scintillation properties as well as segregation of atoms and defects creation processes were carried out. Mg2+ doping in Gd 3 Al 2 Ga 3 O 12 led to the creation of O O • defects localized next to Mg2+ sites due to charge imbalance compensation. Consequently, neutral (Mg Ga/Al/Gd O O) x defects were formed. In Ce3+ doped crystals, Mg2+ codoping changed the valence state from Ce3+ to Ce4+ to maintain charge neutrality. Hence, additional neutral (Ce Gd • -Mg Ga/Al/Gd ′) x and (Ce Gd -Mg Ga/Al/Gd O O) x defects appeared. Moreover, Mg2+ induced charge imbalance in GAGG crystal might also be compensated by the formation of oxygen vacancies (V O •• ). The Mg2+ ions imposed defects deteriorated the segregation of atoms. Accordingly the radial inhomogeneity of the crystals was diminished. The presence of stable Ce4+ and defects imposed by Mg2+ ions codoping were proved by absorption, photoluminescence, and scintillation decay time analysis. Hence, Mg2+ codoping resulted in quenching of the Ce3+ luminescence, acceleration of scintillation response, reduction of light yield, and thermally stimulated luminescence. The mechanism explaining a strong luminescence quenching with increasing Mg2+ ions concentration was proposed. [ABSTRACT FROM AUTHOR]

The influence of the calcination process on the physicochemical properties and catalytic behavior of the Co/Mg/La catalysts for ammonia synthesis has been investigated. The catalysts were prepared using the different thermal pre-treatment methods prior to the activation, i.e., drying and calcination, and the respective activities for ammonia synthesis were assessed. It was found out that changing from air calcination prior to activation to direct activation of the co-precipitated species led to the different catalytic performances. The most favorable catalytic performance was achieved with Co/Mg/La prepared by calcination in air. Detailed characterization methods, employing e.g., XRPD, H2-TPD, N2-TPD, CO2-TPD, SEM, and TEM, showed that the superior catalytic behavior of this catalyst was attributed to its strong basicity and favorable adsorption properties toward hydrogen and nitrogen. [ABSTRACT FROM AUTHOR]

Ni-rich layered oxides, i.e., LiNi0.6Mn0.2Co0.2O2 (NMC622) and LiNiO2 (LNO), were prepared using the two-step calcination procedure. The samples obtained at different calcination temperatures (750–950 °C for the NMC622 and 650–850 °C for the LNO cathode materials) were characterized using nitrogen physisorption, PXRD, SEM and DLS methods. The correlation of the calcination temperature, structural properties and electrochemical performance of the studied Ni-rich layered cathode materials was thoroughly investigated and discussed. It was determined that the optimal calcination temperature is dependent on the chemical composition of the cathode materials. With increasing nickel content, the optimal calcination temperature shifts towards lower temperatures. The NMC-900 calcined at 900 °C and the LNO-700 calcined at 700 °C showed the most favorable electrochemical performances. Despite their well-ordered structure, the materials calcined at higher temperatures were characterized by a stronger sintering effect, adverse particle growth, and higher Ni2+/Li+ cation mixing, thus deteriorating their electrochemical properties. The importance of a careful selection of the heat treatment (calcination) temperature for each individual cathode material was emphasized. [ABSTRACT FROM AUTHOR]

Thermoelectric properties of the half-Heusler phase ScNiSb (space group F 4 ¯ 3m) were studied on a polycrystalline single-phase sample obtained by arc-melting and spark-plasma-sintering techniques. Measurements of the thermopower, electrical resistivity, and thermal conductivity were performed in the wide temperature range 2–950 K. The material appeared as a p-type conductor, with a fairly large, positive Seebeck coefficient of about 240 μV K−1 near 450 K. Nevertheless, the measured electrical resistivity values were relatively high (83 μΩm at 350 K), resulting in a rather small magnitude of the power factor (less than 1 × 10−3 W m−1 K−2) in the temperature range examined. Furthermore, the thermal conductivity was high, with a local minimum of about 6 W m−1 K−1 occurring near 600 K. As a result, the dimensionless thermoelectric figure of merit showed a maximum of 0.1 at 810 K. This work suggests that ScNiSb could be a promising base compound for obtaining thermoelectric materials for energy conversion at high temperatures. [ABSTRACT FROM AUTHOR]