Morphological and optical investigation of 2D material-based ternary nanocomposite: Bi2O3/MgO/GO synthesized by a co-precipitation technique.

A ternary oxide nanocomposite based on Bi2O3/MgO/GO was prepared using a co-precipitation method for photoconductive device applications. The structure and morphology of the as-prepared nanocomposite were characterized analytically using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS) techniques, and optical characterization was made using Fourier-transform infrared (FTIR) spectroscopy, photoluminescence (PL), and UV-vis spectroscopy techniques. The heterostructure of the crystal with a crystallite size of 28.064 nm and the purity of the phase are depicted by XRD patterns. Scanning electron microscopy revealed its morphology showing an average grain size of 0.27 µm, and the purity of the nanocomposite was confirmed by EDS, which showed the presence of Mg, Bi, C, and O. The band gap of the Bi2O3/MgO/GO nanocomposite was 4.02 eV by PL comparable with 5.718 eV by UV-vis spectroscopy, which evidenced that the material may have potential applications in far UVC emissive devices. The zeta potential observed was 48.0 mV, indicating the stability of the ternary nanocomposite.

High performance and gate-controlled GeSe/HfS2 negative differential resistance device.

Transition metal dichalcogenides (TMDs) have received significant attention owing to their thickness-dependent folded current-voltage (I ds-V ds) characteristics, which offer various threshold voltage values. Owing to these astonishing characteristics, TMDs based negative differential resistance (NDR) devices are preferred for the realization of multi-valued logic applications. In this study, an innovative and ground-breaking germanium selenide/hafnium disulfide (p-GeSe/n-HfS2) TMDs van der Waals heterostructure (vdWH) NDR device is designed. An extraordinary peak-to-valley current ratio (≈5.8) was estimated at room temperature and was used to explain the tunneling and diffusion currents by using the tunneling mechanism. In addition, the p-GeSe/n-HfS2 vdWH diode was used as a ternary inverter. The TMD vdWH diode, which can exhibit different band alignments, is a step forward on the road to developing high-performance multifunctional devices in electronics.

Supercooled nano-droplets of water confined in hydrophobic rubber.

Hydrophobic elastomers are capable of absorbing a small amount of water that forms droplets around hydrophilic sites. These systems allow the study of confinement effects by a hydrophobic environment on the dynamics and thermodynamic behaviour of water molecules. The freezing-melting properties and the dynamics of water inside nano-droplets in butyl rubber are affected, as revealed by differential scanning calorimetry (DSC) and deuterium nuclear magnetic resonance (2H-NMR). Upon cooling down, all water crystalizes with a bimodal droplet population (da = 3.4 nm and db = 4.4 nm) in a temperature range associated with the droplet size distribution. However, the melting temperature is not shifted according to the Gibbs-Thomson equation. The relative decrease of the 2H-NMR longitudinal magnetization is not a single exponential and, by inverse Laplace transformation, it was deduced to be bimodal in agreement with the DSC measurements (T1,a ∼ 10 ms and T1,b ∼ 200 ms). The deduced correlation time of molecular reorientation is longer than that of bulk water and the behaviour with temperature follows the Vogel-Fulcher-Tammann (VFT) equations with a changing fragility as the droplet size is reduced when reducing hydration.

Freezing, melting and dynamics of supercooled water confined in porous glass.

The freezing, melting and dynamics of supercooled water at different hydration of controlled porous glass with mean pore sizes 10 nm, 30 nm, 50 nm and 70 nm are studied using differential scanning calorimetry and deuteruim nuclear magnetic resonance (2H-NMR). For saturated samples, the melting temperature follows the Gibbs-Thomson relation despite a clear linear decrease of the melting enthalpy when the transition is shifted due to confinement. For partially filled porous glasses the crystallization and melting temperatures as well as enthalpies are lower than for the saturated samples. 2H-NMR confirms the existence of a non-crystallizable part of water adsorbed on the surface of pores. At room temperature, spin-lattice relaxation rate (1/T 1) is proportional to the inverse of the mean pore size indicating that the relaxation is governed by a surface limited process. At low temperature relaxation rate follows the Vogel-Fulcher-Tammann (VFT) relation.