Positron annihilation spectroscopic characterization of free-volume defects and their correlations with the mechanical and transport properties of SBR-PMMA interpenetrating polymer networks.

A series of interpenetrating polymer networks (IPNs) and semi-interpenetrating polymer networks (s-IPNs) of styrene butadiene rubber (SBR) and poly(methyl methacrylate) (PMMA) have been synthesized by adopting the sequential interpenetration and in situ polymerization method. The size and the concentration of free volume defects in these systems are monitored and their variations accurately traced using positron annihilation lifetime (PALS) and coincidence Doppler broadening spectroscopic (CDBS) measurements. The morphologies of the IPNs were analyzed with transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM).

Defect-Engineered MoS Nanostructures for Reactive Oxygen Species Generation in the Dark: Antipollutant and Antifungal Performances.

Meticulous surface engineering of layered structures toward new functionalities is a demanding challenge to the scientific community. Here, we introduce defects on varied MoS surfaces by suitable doping of nitrogen atoms in a sulfur-rich reaction environment, resulting in stable and scalable phase conversion. The experimental characterizations along with the theoretical calculations within the framework of density functional theory establish the impact of nitrogen doping on stabilization of defects and reconstruction of the 2H to 1T phase.

Magnetic performance and defect characterization studies of core-shell architectured MgFeO@BaTiO multiferroic nanostructures.

Multiferroics that permit manipulation of the magnetization vector exclusively by electric fields have spawned extensive interest for memory and logic device applications. In line with this understanding, we herein report the encapsulation of non-ferroelectric magnesium ferrite (MgFe2O4) nanoparticles in a ferroelectric shell of BaTiO3 to produce a system with engineered dielectric, magnetic, magneto-electric and ferroelectric properties. The interface effect on the strain transfer was observed to strongly influence the magneto-electric coupling and the electric and magnetic properties of the system.

Mn-Doping in NiO Nanoparticles: Defects-Modifications and Associated Effects Investigated Through Positron Annihilation Spectroscopy.

Manganese-doped nickel oxide (Ni1-xMnxO) nanoparticulate samples with x in the range 0 (undoped sample) to 0.35 were synthesized by sol-gel method involving chemical reactions between the solutions of nickel nitrate hexahydrate and manganese acetate tetrahydrate. The nanocrystallites obtained after annealing of the precipitates for different durations were characterized by X-ray diffraction and high resolution transmission electron microscopy.

Effects of process parameters on the defects in graphene oxide-polyaniline composites investigated by positron annihilation spectroscopy.

Graphene oxide (GO)-polyaniline (PANI) composites were prepared with different relative abundance of PANI and GO by in situ polymerization of aniline in the presence of GO and ammonium persulphate at different temperatures. In the process, GO also got reduced to graphene. Positron lifetimes and coincidence Doppler broadening of the electron-positron annihilation gamma ray spectra originating from the composite samples were measured and the results are reported.

A positron annihilation spectroscopic investigation of europium-doped cerium oxide nanoparticles.

Doping in ceria (CeO2) nanoparticles with europium (Eu) of varying concentrations (0, 0.1, 0.5, …, 50 atom%) is studied using complementary experimental techniques and novel observations were made during the investigation.

Mn(2+)-induced substitutional structural changes in ZnS nanoparticles as observed from positron annihilation studies.

Zinc sulfide nanoparticles doped with different concentrations of manganese ions (Mn(2+)) were synthesized at various temperatures to investigate the effects of substitution and the associated defect evolution. Positron lifetime and Doppler broadening measurements were used as probes. The initial stage of defect recovery was dominated by the occupation of Zn(2+) vacancies by Mn(2+) ions, bringing in characteristic changes in the positron lifetimes, intensities and Doppler broadened lineshape parameters.

Positron annihilation spectroscopic studies of solvothermally synthesized ZnO nanobipyramids and nanoparticles.

Zinc oxide (ZnO) samples in the form of hexagonal-based bipyramids and particles of nanometer dimensions were synthesized through solvothermal route and characterized by x-ray diffraction and transmission electron microscopy. Positron annihilation experiments were performed to study the structural defects such as vacancies and surfaces in these nanosystems. From coincidence Doppler broadening measurements, the positron trapping sites were identified as Zn vacancies or Zn-O-Zn trivacancy clusters.

Positron annihilation studies of defects and interfaces in ZnS nanostructures of different crystalline and morphological features.

Nanostructures of ZnS, both particles and rods, were synthesized through solvothermal processes and characterized by x-ray diffraction and high resolution transmission electron microscopy. Positron lifetime and Doppler broadening measurements were made to study the features related to the defect nanostructures present in the samples. The nanocrystalline grain surfaces and interfaces, which trapped significant fractions of positrons, gradually disappeared during grain growth, as indicated by the decreasing fraction of orthopositronium atoms.