Synthesis of Hydrogen Getter Zr1-xCox (x=0-1) Alloy Films by Magnetron Co-Sputtering

The Zr1-xCox(x=0, 0.25, 0.53, 0.63, 1) thin films were deposited on quartz substrate using magnetron co-sputtering of Zirconium and Cobalt targets in confocal geometry. A constant pulsed direct current (PDC) on Zirconium and radio frequency (RF) of various powers on Cobalt target were applied to vary the concentration of Co in the Zr1-xCox film. The film composition was quantified using EDX measurements. The hydrogen storage capacity of these films was studied using an in-house developed hydrogen adsorption setup, in which the electrical resistivity of the film was monitored as a function of hydrogen partial pressure and temperature. The films' surface morphology and crystal structure before and after hydrogenation were characterized using atomic force microscopy and grazing incidence X-ray diffraction techniques using synchrotron radiation, respectively. An increase in the particle size after hydrogenation was observed for all the films. An increase in resistivity was also observed due to the absorption of hydrogen in all the compositions. The near stoichiometric film Zr0.47Co0.53 showed the highest hydrogen absorption level at 200 oC at all partial pressures. However, a decrease in the response at temperatures higher than 200 oC was observed in the film containing a Co concentration. The mechanism for the increase in resistivity of the film on hydrogenation is explained. Keywords: ZrCo alloy, hydrogen getter, magnetron co-sputtering, four-probe resistivity, thin film

Influence of spin-state transition on structural and other physical properties in Ba0.5Sr0.5Co0.8Fe0.2O3-delta ceramic

We explore, in detail, the remarkable influence of spin-state transition - low (S = 1/2) to high spin (S = 5/2) - on crystallographic, thermal, electrical, and mechanical properties in Ba0.5Sr0.5Co0.8Fe0.2O3-delta ceramic. The low to high spin transition takes place at T* similar to 600 K with a rather broad transition zone of nearly 200 K. We find that the electrical resistivity, mechanical stiffness and toughness, thermal expansion coefficient, and the crystallographic structure exhibit clear anomalous features around T*. The transition, however, appears to be isostructural Pm (3) over barm -> Pm (3) over barm (cubic -> cubic). Significant influence of spin-state transition on a variety of properties could have serious implications for several applications ranging from magnetic sensors to electrocatalysts to ion separation membranes

Unraveling the Magnetic Ground State and Local Lattice Distortions in Z₂XY-Type Full Heusler Compounds: An EXAFS Study

We present a detailed investigation into the correlations between the magnetic and local structural order of Ga2MnCo and three new compositions Al2MnCo, Ga2MnPd, and Al2MnPd, which belong to the composition range with dominant p–d hybridization in the extended Heusler family. Our investigations reveal that such systems do not have a propensity to form in the regular face-centered cubic structure with ferromagnetic ordering as its magnetic ground state. The studied compositions are found to demonstrate a re-entrant cluster-glass state. The absence of any associated structural phase transitions in these compositions is ensured from the heat capacity and temperature-dependent X-ray absorption fine structure (XAFS) spectroscopy measurements. The magnetic susceptibility results demonstrate the formation of macroscopic spin clusters, and XAFS identifies the correlation between spin and lattice degrees of freedom. While the inherent anti-site disorder provides the competing interactions, a complex interaction mechanism between the sp and different d atoms, along with an unusual local lattice disorder in these cubic compounds, may act as precursors for the frozen magnetic state. Additionally, the experimental X-ray absorption near-edge structure reflects the electronic features, which hints toward a stronger p–d hybridization in the systems

Magnetic properties of FeCo alloy nanoparticles synthesized through instant chemical reduction

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<i>In Vitro</i> Investigation Unveiling New Insights into the Antimalarial Mechanism of Chloroquine: Role in Perturbing Nucleation Events during Heme to β‑Hematin Transformation

Malaria parasites generate toxic heme during hemoglobin digestion, which is neutralized by crystallizing into inert hemozoin (β-hematin). Chloroquine blocks this detoxification process, resulting in heme-mediated toxicity in malaria parasites. However, the exact mechanism of chloroquine’s action remains unknown. This study investigates the impact of chloroquine on the transformation of heme into β-hematin. The results show that chloroquine does not completely halt the transformation process but rather slows it down. Additionally, chloroquine complexation with free heme does not affect substrate availability or inhibit β-hematin formation. Scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) studies indicate that the size of β-hematin crystal particles and crystallites increases in the presence of chloroquine, suggesting that chloroquine does not impede crystal growth. These findings suggest that chloroquine delays hemozoin production by perturbing the nucleation events of crystals and/or the stability of crystal nuclei. Thus, contrary to prevailing beliefs, this study provides a new perspective on the working mechanism of chloroquine