Publications by authors named "Vasant Sathe"

Article Synopsis
  • Piezoresponse force microscopy (PFM) is a powerful technique for studying ferroelectric materials at a nanoscale but can produce misleading signals due to electrostatic interactions.
  • The study introduces a calibration process and a method to identify the parasitic phase offset, enhancing the accuracy of the phase-amplitude loops.
  • The techniques combine switching spectroscopy-PFM (SS-PFM) and Kelvin probe force microscopy (KPFM) to quantify local imprint voltages in various materials, revealing the significance of correct read voltage selection and allowing detailed mapping of imprint voltage variations in BaTiO single crystals.
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We have performed a comprehensive study to explore the effect of Sr substitution on the structural and ferroelectric properties of BaTiO(BTO) with compositions BaSrTiOfor 0 ⩽⩽ 1. The room temperature structural investigation inferred that the samples with compositions> 0.30 has cubic phase instead of tetragonal as for pristine BTO.

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Article Synopsis
  • Ferroelectric domain walls are important for nanoelectronic devices due to their sensitivity to external stimuli, particularly optical signals.
  • Researchers demonstrated that in-plane polarized subdomains in ferroelectric BaTiO can be controlled optically, allowing for reversible movement of domain walls.
  • The study also suggests that flexoelectricity, rather than long-range ferroelectric polarization, plays a crucial role in optical control, making ferroelastic materials viable for future nanoelectronics.
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Coupling of orbital degree of freedom with a spin exchange, i.e., Kugel-Khomskii-type interaction (KK), governs a host of material properties, including colossal magnetoresistance, enhanced magnetoelectric response, and photoinduced high-temperature magnetism.

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A rapid, clean plasma-chemical technique is demonstrated here, for cost-effective, synthesis of surface vacancy engineered, 2D, molybdenum-oxide nanomaterials, during a one-step, integrated synthesis-hydrogenation process for biomedical applications. A laminar plasma beam populated with O and H radicals impinges on a molybdenum target, out of which molybdenum-oxide nanomaterials are very rapidly generated with controlled surface O vacancies. 2D, dark-blue coloured, nano-flake/ribbon like MoOis produced maximum up to 194 g h, the core of which still remains as stoichiometric molybdenum-oxide.

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The prevalent material design principles for optical thermometry primarily rely on thermally driven changes in the relative intensities of the thermally coupled levels (TCLs) of rare-earth-doped phosphor materials, where the maximum achievable sensitivity is limited by the energy gap between the TCLs. In this work, a new, to the best of our knowledge, approach to thermometric material design is proposed, which is based on temperature tuning of PL emission from the visible to the NIR region. We demonstrate a model ferroelectric phosphor, Eu-doped 0.

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Numerous amorphous solid dispersion (ASD) formulations of celecoxib (CEL) have been attempted for enhancing the solubility, dissolution rate, and in vivo pharmacokinetics via high drug loading, polymer combination, or by surfactant addition. However, physical stability for long-term shelf life and desired in vivo pharmacokinetics remains elusive. Therefore, newer formulation strategies are always warranted to address poor aqueous solubility and oral bioavailability with extended shelf life.

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Article Synopsis
  • - The study examines the double perovskite compound TbCoMnO using various techniques, revealing the coexistence of anti-ferromagnetic (AFM) and ferromagnetic (FM) phases.
  • - Analysis shows that anti-site disorder (ASD) contributes to spin frustration at low temperatures, leading to a cluster glass state around 33 K.
  • - The research links phonon and spin interactions in the material, and findings from theoretical calculations align well with the experimental observations.
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Direct engineering of material properties through exploitation of spin, phonon, and charge-coupled degrees of freedom is an active area of development in materials science. However, the relative contribution of the competing orders to controlling the desired behavior is challenging to decipher. In particular, the independent role of phonons, magnons, and electrons, quasiparticle coupling, and relative contributions to the phase transition free energy largely remain unexplored, especially for magnetic phase transitions.

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In the present attempt, a Dy, W co-doped La2Mo2O9 (LMX) system is explored to understand the order-disorder phase transition, dynamical disorder state and their influence on the oxy-ion diffusion mechanism. The X-ray diffraction study confirms the co-dopant induced suppression of the order-disorder phase transition temperature of LMX. The oxygen ion diffusion in the LMX matrix is through intrinsic oxygen vacancies.

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This is the first report on the enhanced thermoelectric (TE) properties of novel reaction-temperature () and duration-induced BiS-Bi nanocomposites synthesized using a facile one-step polyol method. They are well characterized as nanorod composites of orthorhombic BiS and rhombohedral Bi phases in which the latter coats the former forming BiS-Bi core-shell-like structures along with independent Bi nanoparticles. A very significant observation is the systematic reduction in electrical resistivity ρ with a whopping 7 orders of magnitude (∼10) with just reaction temperature and duration increase, revealing a promising approach for the reduction of ρ of this highly resistive chalcogenide and hence resolving the earlier obstacles for its thermoelectric application potentials in the past few decades.

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The effect of Sr doping in BaTiO(BTO) with nominal compositions BaSrTiO(BSTO) have been explored on its structural, lattice vibration, dielectric, ferroelectric and electrocaloric properties. The temperature dependent dielectric results elucidate the enhancement in dielectric constant and exhibit three frequency independent transitions around 335, 250 and 185 K, which are related to different structural transitions. All these transitions occur at lower temperature as compared with pristine BTO, however; remnant electric polarization () of BSTO is much higher than in BTO.

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In this work, we have presented a solid-solution of SmDyFeOin the form of nano-particles having spin reorientation transition (SRT) at a temperature interval of 220-260 K. The lattice dynamics of SmDyFeOhave investigated by temperature-dependent x-ray diffraction and Raman spectroscopy. A negative thermal expansion at low temperatures has observed, which might be due to the interaction between Smand Fesublattice.

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An investigation has been carried out on the spin phonon coupling in a series of isostructural polycrystalline orthorhombic (Space group Pnma) compounds HoFe Mn O (x  ⩽  0.6) exhibiting spin reorientation below Néel temperature (T ), using magnetization, neutron diffraction, and Raman scattering techniques. Mn doping leads to an anomalous increase in the spin reorientation temperature (T ), shifting it close to room temperature from T ~ 60 K for x  =  0 sample, and concomitant lowering of T .

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The paradigm that chemical synthesis reduces the sintering temperature as compared to solid state synthesis seems to be violated in the case of the PrBaCo2O6-δ double perovskite. The sintering temperatures for pure phase samples synthesized through the solid state route (P-SSR) and the auto-combustion route (P-ACR) were found to be 1050 and 1150 °C, respectively. The porous microstructure of P-SSR is suitable for SOFC cathode materials while that of P-ACR is pore free.

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Oxidation and reduction reactions are of central importance in chemistry as well as vital to the basic functions of life and such chemical processes are generally brought about by oxidizing and reducing agents, respectively. Herein, we report the discovery of an interfacial reduction reaction (IRR) - without the use of any external reducing agent. In course of metal-ligand coordination, spontaneous reduction of Cu(II) to Cu(I) at a solid-liquid interface was observed-unlike in a liquid-phase reaction where no reduction of Cu(II) to Cu(I) was occurred.

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A piezoelectric material KNbO3 has been co-substituted with the magnetic ions Sm3+ and Fe3+ in order to explore the relation between piezoelectricity and magnetism. The samples K1-xSmxNb1-xFexO3 [x = 0.0-0.

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The competition and cooperation between ferroelectric and anti-ferro-distortion (AFD) instabilities are studied using pressure dependent Raman spectroscopy on polycrystalline powder samples of Sr Ca TiO(x  =  0.0, 0.06, 0.

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We report the infrared absorption and Raman spectra of melatonin recorded with 488 and 632.8 nm excitations in 3600-2700 and 1700-70 cm(-1) regions. Further, we optimized molecular structure of the three conformers of melatonin within density functional theory calculations.

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Silica-coated, silicon nanotubes (SCSNTs) and silica-coated, silicon nanoparticles (SCSNPs) have been synthesized by catalyst-free single-step gas phase condensation using the arc plasma process. Transmission electron microscopy and scanning tunneling microscopy showed that SCSNTs exhibited a wall thickness of less than 1 nm, with an average diameter of 14 nm and a length of several 100 nm. Both nano-structures had a high specific surface area.

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Dielectric, structural and Raman investigations were carried out on a perovskite-based solid solution of (NBT)((1 - x))(BiCrO(3))(x) (x = 0.00, 0.05, 0.

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High coercivity (9.47 kOe) has been obtained for oleic acid capped chemically synthesized CoFe(2)O(4) nanoparticles of crystallite size approximately 20 nm. X-ray diffraction analysis confirms the formation of spinel phase in these nanoparticles.

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Thin films of zinc phthalocyanine have been deposited on KBr and glass substrates by the thermal evaporation method and characterized by the x-ray diffraction, optical, infrared and Raman techniques. The observed x-ray diffraction and infrared absorption spectra of as-deposited thin films suggest the presence of an α crystalline phase. Infrared and Raman spectra of thin films after exposure to vapours of ammonia and methanol have also been recorded.

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Article Synopsis
  • The study investigates how mixing occurs in a tri-layer structure composed of silicon (Si) and titanium (Ti) when bombarded with high-energy gold (Au) ions.
  • Researchers used advanced X-ray techniques to create a precise depth profile of the Ti layer, revealing how different thicknesses impact the intermixing process.
  • It was found that a thinner (2 nm) Ti layer experiences more intense intermixing compared to a thicker (6 nm) layer, attributed to the energy confinement differences, with the thicker layer showing asymmetric intermixing due to potential structural irregularities at the interfaces.
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