Single crystal synthesis and physical property of Ba8Cu1·0Ni2.5Ga10Si33.5 clathrate.

This study reports the synthesis of type-I Ba8CuNi2.5Ga10Si33.5 clathrate as a single crystal by the flux method and physical properties investigations such as structural, chemical, magnetic, and thermal properties. Structural refinements indicate Ba atoms are situated at 2a and 6d positions with mixed occupancy across framework sites. Raman spectroscopy assessed host-guest interactions, while the compound's morphology and composition were investigated by the scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) analyses. Magnetic properties revealed ferromagnetic interactions characterized by a positive Weiss constant and weak ferromagnetic hysteresis. The compound's metallic nature is evidenced by increased resistivity with temperature. The Sommerfeld coefficient, estimated at 12.59 mJ mol-1 K-2 from heat capacity data, alongside a pronounced peak around 15 K in the Cp/T3 vs T plot, suggests an Einstein contribution in heat capacity.

Knowledge management and ethical vulnerability in AI.

We have covered the current and future prospects of the combined use of AI and KM with respect to the Indian economy and its future automation prospects. The most likely fields to see automation in the coming years that would help the Indian approach to this field to be more efficient have been covered by us. Certain fields such as healthcare, farming, finances, and the IT sector are the primary concern around which the future prospects of India evolve. All in all, we have discussed the ethical vulnerability and ways to cope up and fill the gap between the goal and the issues that coincide.

Synthesis and Characterization of Sodium-Iron Antimonate Na2FeSbO5: One-Dimensional Antiferromagnetic Chain Compound with a Spin-Glass Ground State.

A new oxide, sodium-iron antimonate, Na2FeSbO5, was synthesized and structurally characterized, and its static and dynamic magnetic properties were comprehensively studied both experimentally by dc and ac magnetic susceptibility, magnetization, specific heat, electron spin resonance (ESR) and Mössbauer measurements, and theoretically by density functional calculations. The resulting single-crystal structure (a = 15.6991(9) Å; b = 5.3323 (4) Å; c = 10.8875(6) Å; S.G. Pbna) consists of edge-shared SbO6 octahedral chains, which alternate with vertex-linked, magnetically active FeO4 tetrahedral chains. The 57Fe Mössbauer spectra confirmed the presence of high-spin Fe3+ (3d5) ions in a distorted tetrahedral oxygen coordination. The magnetic susceptibility and specific heat data show the absence of a long-range magnetic ordering in Na2FeSbO5 down to 2 K, but ac magnetic susceptibility unambigously demonstrates spin-glass-type behavior with a unique two-step freezing at Tf1 ≈ 80 K and Tf2 ≈ 35 K. Magnetic hyperfine splitting of 57Fe Mössbauer spectra was observed below T* ≈ 104 K (Tf1 < T*). The spectra just below T* (Tf1 < T < T*) exhibit a relaxation behavior caused by critical spin fluctuations, indicating the existence of short-range correlations. The stochastic model of ionic spin relaxation was used to account for the shape of the Mössbauer spectra below the freezing temperature. A complex slow dynamics is further supported by ESR data revealing two different absorption modes presumably related to ordered and disordered segments of spin chains. The data imply a spin-cluster ground state for Na2FeSbO5.

New series of honeycomb ordered oxides, Na3M2SbO6 (M(ii) = Mn, Fe, (Mn, Fe), (Mn, Co)): synthesis, structure and magnetic properties.

New layered oxides, Na3M2SbO6 (M(ii) = Mn, Fe) have been synthesized by solid state reactions under inert conditions. Rietveld refinements of the powder X-ray diffraction measurements confirmed the structures in the C2/m space group. The layered structure consists of honeycomb slabs with ordered M2+ (Mn or Fe) and Sb5+ cations, separated by Na+ ions in the interlayer octahedral sites. X-ray photoelectron spectroscopy measurements further substantiated the presence of Mn2+, Fe2+ and Sb5+ ions. A paramagnetic behavior has been exhibited by Na3Mn2SbO6 in the range of 300-100 K with negative Weiss constant (θ = -144 K). Zero field cooled and field cooled values diverged below 50 K and without the indication of a long-range antiferromagnetic order down to 2 K. On the other hand, Na3Fe2SbO6 has been found to display two different transitions in the magnetic susceptibility measurements. A distinct cusp appeared around T∼ 120 K followed by the divergence between the zero field cooled and the field cooled values. The observation of antiferromagnetic ordering (TN∼ 7.5 K) suggested the magnetic frustration behavior arising out of the placement of Fe2+ ions in the triangular lattice of the honeycomb layers. Partial substitution of Mn2+ ions by Fe2+ and Co2+ ions has resulted in isostructural Na3MnFeSbO6 and Na3MnCoSbO6 under similar experimental conditions. Magnetic properties have been significantly modified by the coexistence of Mn2+ and Fe2+ ions in Na3MnFeSbO6. Co2+ substitution resulted in paramagnetic behavior with θ∼-8.4 K confirming thereby the competing antiferromagnetic interactions. The scope of the present work has been explored by carrying out the ion-exchange experiments of the sodium analogues using molten salt (LiNO3) to synthesize new Li3M2SbO6 (M = Mn, Fe) oxides.

Catalytic Application of Oxygen Vacancies Induced by Bi3+ Incorporation in ThO2 Samples Obtained by Solution Combustion Synthesis.

Recognizing immense advantages of solution-based combustion synthesis, its applicability to determine the extent of dissolution of Bi3+ in fluorite-structured thoria has been examined to generate high-surface-area samples with massive defects. Up to 50 mol % of thorium could be substituted with bismuth retaining fluorite structure beyond which phase separation occurred. The lattice parameters from Le-Bail refinements of their powder X-ray diffraction patterns showed marginal increase with increase in bismuth content, suggesting the competing effect between the size of the cation and the oxygen vacancy concentration. Energy-dispersive X-ray spectrometry analysis and high-resolution transmission electron microscopy measurements have also confirmed the composition and structure of the limiting composition. With progressive bismuth content, the band due to the fluorite (at 460 cm-1) diffused and a defect band in the region 570-600 cm-1 emerged in the Raman spectra. From these changes, the oxygen vacancy concentrations in these samples have been determined, which increased with increase in bismuth content. Absorbance in the visible region was noticed for bismuth-containing samples, and band gap values determined from the Kubelka-Munk function were in the range 2.34-3.24 eV. In addition to the blue emission from oxygen vacancies, 3P1 → 1S0 transition of Bi3+ was noticed in the photoluminescence spectrum. From Brunauer-Emmett-Teller measurements, the surface area of Th0.50Bi0.50O2-δ obtained by solution combustion synthesis was measured to be 265.74 m2 g-1, higher than the value (39.00 m2 g-1) for the sample prepared by solid-state synthesis. All of these factors combined with oxygen vacancies as defect centers have been found to play critical control over their use as catalyst for the reductive transformation of nitroaromatics and oxidative decolorization of organic dye molecules (methyl orange and xylenol orange). A nice correlation between oxygen vacancy concentration and pseudo first-order rate constants of these catalytic conversions has been arrived. The catalyst was found to retain its efficiency up to four cycles without undergoing any structural change during these experiments.