Identification of high ionic conducting members (M(III) = Co, Ni) in the new lithium rich Li4.50M0.50TeO6 (M(III) = Co, Ni, In) series.

Many new lithium-excess compounds with rock-salt related structures have been extensively studied in recent years to discover high-capacity electrode materials for lithium-ion batteries. In the present work, lithium rich layered tellurates, Li4.50M0.50TeO6 (M(III) = Co, Ni, In), are added to the existing series of Li4.50M0.50TeO6 (M(III) = Cr, Mn, Fe, Al, and Ga) oxides. Structural investigations revealed their stabilization in the space group C2/m with a new cationic ordering. The structure consists of (Li1.50M0.50TeO6)3- honeycomb arrays along the ab plane by the edge sharing of TeO6 with (Li/M)O6 octahedra. The honeycomb arrays are separated by the intermediate layer of Li alone in Li4.50Co0.50TeO6. On the other hand, in the Ni and In analogues, the interlayer region consists of Li with Te, and Li with In ions, respectively. XPS studies confirmed the +3 oxidation state of Co and Ni ions. The appearance of a strong band at 680 nm resulting from LMCT (O → Co) in the UV-vis DRS data of the Li4.50Co0.50TeO6 sample further indicated the presence of Co3+ (d6, low spin) ions. The absence of characteristic Ni2+ bands at around ∼650 and 740 nm supported Ni3+ ions. Li4.50Co0.50TeO6 showed diamagnetic behaviour, while Li4.50Ni0.50TeO6 displayed paramagnetic nature. A negative θ (-14(2)) K has been obtained in the temperature region of 300-100 K for Li4.50Ni0.50TeO6 representing dominant antiferromagnetic interactions. At 2 K, Li4.50Ni0.50TeO6 unveiled a non-linear trend with no significant hysteresis and nearly saturation at 5 T field indicating the existence of additional interactions. Li4.50Co0.50TeO6 and Li4.50Ni0.50TeO6 exhibited significant conductivity values of 0.016 and 0.003 S cm-1, respectively, at 300 °C, thereby opening up further studies in this direction.

Evidence of Long-Range and Short-Range Magnetic Ordering in the Honeycomb Na3Mn2SbO6 Oxide.

We present a comprehensive study of the synthesis, structure, and magnetic properties of the honeycomb oxide Na3Mn2SbO6 supported by neutron diffraction, heat capacity, and magnetization measurements. The refinements of the neutron diffraction patterns (150, 50, and 45 K) using the Rietveld method confirm the monoclinic (S. G. C2/m) structure. Temperature-dependent magnetic susceptibilities measured at varying fields along with the heat capacity measurements demonstrate the coexistence of long-range ordering (∼42 K) and short-range ordering (∼65 K). The field-dependent isothermal magnetization measurements at 5 K indicate a spin-flop transition around 5 T. Rietveld refinements of the low-temperature (below 45 K) neutron diffraction data further confirm the long-range magnetic ordering. In addition, the temperature variation of the lattice parameters obtained from the neutron powder diffraction analysis exhibited a distinct anomaly near the antiferromagnetic transition temperature. The appearance of the concomitant broadened backgrounds in the neutron powder diffraction data collected at 80, 50, and 45 K supports the short-range ordering. The resultant magnetic structure consists of spins that are aligned antiparallel with the nearest neighbors and also with the spins of the adjacent honeycomb layers. The occurrence of a fully ordered magnetic ground state (Neel antiferromagnetic (AFM)) in Na3Mn2SbO6 consolidates the significance of fabricating new honeycomb oxides.

Antioxidant additive melatonin in tris-based egg yolk extender improves post-thaw sperm attributes in Hariana bull.

In the study, melatonin, a known antioxidant pineal peptide was used as an additive in the tris-egg yolk glycerol-based semen extender in Hariana bull semen and post-thaw sperm characters were evaluated. In the study, Group I was a control without melatonin; and Group II, III, and IV were having 0.5 mM, 1 mM, and 2 mM melatonin/80 × 106 spermatozoa, respectively were treatment groups. Thirty-two semen ejaculates from 4 Hariana bulls were processed for freezing and post-thaw sperm characteristics were evaluated. Sperm motility, velocity, the viability with intact membrane, and total antioxidant capacity were markedly (P < 0.05) improved in Group IV compared to all other groups. The lipid peroxidation and total protein carbonylation were substantially (P < 0.05) decreased in Group IV compared to all other groups. The population of cryocapacitated, acrosome-reacted, and apoptotic-like spermatozoa were significantly (P < 0.05) decreased in Group IV. Further, the relative band intensity of 74 kDa protein and percent of spermatozoa showing positive immune reactivity to tyrosine-phosphorylated proteins was decreased in Group IV. The progesterone-receptor ligand binding, in vitro capacitation response, and Vanguard distance were markedly (P < 0.05) improved in Group IV. In summary- Group IV having 2 mM melatonin was found to be optimal in providing cryoprotective effects to Hariana bull spermatozoa after freezing-thawing and can be suitably used as a semen additive during semen cryopreservation.

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.