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Temperature evolution of magnetic properties in Ba and Ti doped SrRuO3 has been investigated to observe the effects of larger ionic radius Ba at Sr site and isovalent nonmagnetic impurity Ti at Ru site. Ionic radius mismatch and different electronic configuration in comparison with Ru modify Sr(Ba)-O and Ru(Ti)-O bond lengths and Ru-O-Ru bond angle. The apical and basal Ru-O-Ru bond angles vary significantly with Ti doping. Ferromagnetic Curie temperature decreases from 161K to 149K monotonically with Ba (10%) and Ti (10%) substitutions at Sr and Ru sites. The zero field cooled (ZFC) magnetization reveals a prominent peak which shifts towards lower temperature with application of magnetic field. The substitution of tetravalent Ti with localized 3d0 orbitals for Ru with more delocalized 4d4 orbitals leads to a broad peak in ZFC magnetization. A spontaneous ZFC magnetization becomes negative below 160K for all the compositions. The occurrence of both normal and inverse magnetocaloric effects in Ba and Ti co-doped SrRuO3 makes the system more interesting. [ABSTRACT FROM AUTHOR]

There is an undying need for inexpensive, energy efficient and eco-friendly protocols to produce biocompatible nanoparticles to be used in the field of medicine. To address this issue, exploratory research was performed to produce silver nanoparticles (AgNPs) using a novel strain of Kitasatospora albolonga isolated during the course of the study. The objective was to test their antimicrobial activity against Multi Drug Resistant (MDR) Pseudomonas aeruginosa. UV-visible spectroscopy, dynamic light scattering (DLS), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) confirmed the presence of hybrid AgNPs. UV-visible spectroscopy showed a localized surface plasmon resonance (LSPR) absorption peak at approximately 420 nm. The DLS and SEM micrographs showed spherical particles ranging between 10 and 50 nm in size. XRD indicated a highly frustrated system comprising silver (cubic, Fm%3m) and silver oxide (cubic, pn%3m: 1) phases as identified from the diffraction peaks. The crystallite sizes of silver (Ag) were smaller than those of silver oxide (Ag2O), indicating a possible core shell structure, also corroborated by the SEM and TEM studies. The Ag/Ag2O hybrid nanoparticles (NPs) exhibited antimicrobial activity against MDR P. aeruginosa. The NP impregnated discs were compared with various commercially available antibiotic discs. Most of the antibiotic discs did not inhibit the growth of the MDR strain alone or in combination with the NPs. However, a synergistic action between Ag/Ag2O NPs and carbenicillin (CN) drug was observed through the checkerboard assay against the MDR hospital isolate. The efficacy of this combination proved to be a lethal and viable option against MDR P. aeruginosa. [ABSTRACT FROM AUTHOR]

Temperature evolution of magnetic properties in Ba and Ti doped SrRuO3 has been investigated to observe the effects of larger ionic radius Ba at Sr site and isovalent nonmagnetic impurity Ti at Ru site. Ionic radius mismatch and different electronic configuration in comparison with Ru modify Sr(Ba)-O and Ru(Ti)-O bond lengths and Ru-O-Ru bond angle. The apical and basal Ru-O-Ru bond angles vary significantly with Ti doping. Ferromagnetic Curie temperature decreases from 161K to 149K monotonically with Ba (10%) and Ti (10%) substitutions at Sr and Ru sites. The zero field cooled (ZFC) magnetization reveals a prominent peak which shifts towards lower temperature with application of magnetic field. The substitution of tetravalent Ti with localized 3d0 orbitals for Ru with more delocalized 4d4 orbitals leads to a broad peak in ZFC magnetization. A spontaneous ZFC magnetization becomes negative below 160K for all the compositions. The occurrence of both normal and inverse magnetocaloric effects in Ba and Ti co-doped SrRuO3 makes the system more interesting. [ABSTRACT FROM AUTHOR]

Magnetic interfaces created by the formation of a nanocomposite of ferromagnetic BiFeO3 nanoparticles of mean size 11 nm and antiferromagnetic network-like nanostructured NiO are studied. The effective radius of the ferromagnetic region is smaller than the actual nanoparticle size, thus confirming the involvement of a large fraction of surface spins in the interfacial magnetism. The exchange coupling between the BiFeO3 nanoparticles and the network-like nanostructured NiO leads to an interfacial blocking phase having an average blocking temperature of about 80 K. The temperature dependent saturation magnetization follows the Bloch law at high (150–300 K) temperature and exponential behaviour in intermediate (25–150 K) and low (5–25 K) temperature regimes. Exchange bias appears below the irreversible temperature of about 300 K, well below the Néel temperature of NiO. The composition dependences of the exchange bias field (HEB) and the coercivity (HC) reveal maximum values of HEB = 1550 Oe and HC = 1730 Oe at 5 K and a cooling field of 50 kOe for a BiFeO3 : NiO :: 50 : 50 concentration ratio. The exchange bias field decreases exponentially with increase of the temperature. Strong interfacial coupling due to uncompensated surface spins leads to a remarkable enhancement of the magnetic anisotropy at the BiFeO3/NiO interface. [ABSTRACT FROM AUTHOR]

Indium sulphide (In2S3) quantum dots (QDs) of average size 6 ± 2 nm and hexagonal nanoplatelets of average size 37 ± 4 nm have been synthesized from indium myristate and indium diethyl dithiocarbamate precursors respectively. The absorbance and emission band was tuned with variation of nanocrytal size from very small in the strong confinement regime to very large in the weak confinement regime. The blue emission and its shifting with size has been explained with the donor-acceptor recombination process. The 3d element doping (Mn(2+) and Cu(2+)) is found to be effective for formation of new emission bands at higher wavelengths. The characteristic peaks of Mn(2+) and Cu(2+) and the modification of In(3+) peaks in the x-ray photoelectric spectrum (XPS) confirm the incorporation of Mn(2+) and Cu(2+) into the In2S3 matrix. The simulation of the electron paramagnetic resonance signal indicates the coexistence of isotropic and axial symmetry for In and S vacancies. Moreover, the majority of Mn(2+) ions and sulphur vacancies (VS ) reside on the surface of nanocrystals. The quantum confinement effect leads to an enhancement of band gap up to 3.65 eV in QDs. The formation of Mn 3d levels between conduction band edge and shallow donor states is evidenced from a systematic variation of emission spectra with the excitation wavelength. In2S3 QDs have been established as efficient sensitizers to Mn and Cu emission centers. Fast and slow components of photoluminescence (PL) decay dynamics in Mn and Cu doped QDs are interpreted in terms of surface and bulk recombination processes. Fast and stable photodetctors with high photocurrent gain are fabricated with Mn and Cu doped QDs and are found to be faster than pure In2S3. The fastest response time in Cu doped QDs is an indication of the most suitable system for photodetector devices.