Lead free dielectric materials of Strontium Bismuth Niobate SrBi2Nb2O9 (SBN) and rare earth double doped SrBi1.8Pr0.1Gd0.1Nb2O9 (SBPGN), SrBi1.8Pr0.1Y0.1Nb2O9 (SBPYN), SrBi1.8Eu0.1Gd0.1Nb2O9 (SBEGN) and SrBi1.8Eu0.1Y0.1Nb2O9 (SBEYN) were prepared by two-stage solid-state reaction route. The XRD studies have confirmed the formation of single-phase orthorhombic crystal structure. The microstructural analysis showed the formation of plausible needle shaped grains in the prepared ceramics. The FTIR study was used to investigate the effect of preparation and doping processes on the band intensities of the spectra. Mechanical studies showed that SBEGN and SBEYN ceramics exhibited mild wear (<10−6 mm3 Nm−1) compared to others. The low friction coefficient values of SBPYN (0.044), SBEGN (0.058) and SBEYN (0.002) to that of SBN necessitate lattice strain in these materials. The VSM studies on the rare earth double doped SBN ceramic materials confirmed the induction and existence of magnetic order in SBPGN and SBEGN.

No abstract

The ferroelectric perovskite SrBi2Nb2O9 (SBN) material with a low concentration of double doping at the Bi-site of SBN was studied to understand its influence and usefulness in integrated optoelectronic, soft magnetic memory devices and wear-resistant tribomaterials. The aim of the present study is double doping of SBN with a set of rare earth elements Pr3+/Dy3+ (SBPDN), Pr3+/Gd3+ (SBPGN), Pr3+/Sm3+ (SBPSN), and Pr3+/Y3+ (SBPYN) at the Bi-site of SBN to establish the multifunctional ceramic nature pertaining to diverse applications. XRD with Rietveld refinement analysis acknowledged a single-phase orthorhombic structure with an increase in lattice parameters and unsystematic changes in crystallite size. SEM study indicated that the samples possessed non-uniformly distributed needle-shaped grains. The purity of the material and the detection of functional groups were received from the EDS and FTIR spectroscopy. Structural modifications in SBN have been determined based on a diffuse reflectance spectroscopy (DRS) study and therefore the band gap values decrease from 2.98 eV (SBN) to 2.70 eV (double doping) because of the growth of distortion in the structure and pronounced increase in the density of localized states. Photoluminescence (PL) study on double doped SBN material with an excitation wavelength of 320 nm has yielded a novel red emission at 609 nm, that may be useful for white LEDs. The ferromagnetic signature in the studied materials was confirmed from the room temperature VSM study. Noticed mild wear and a low coefficient of friction in the studied materials of SBPDN and SBPSN compared to other studied ceramic samples from mechanical studies. The simultaneous manifestation of optical, magnetic, and mechanical properties by double-doped SBN ceramics keeps the materials as multi-functional candidates for optoelectronic devices, soft magnetic memory devices, and wear-resistant tribomaterials.

No abstract

In the present study, Zn1-x Gdx O (x=0.02) nanoparticles have been synthesized by chemical route (Sol-Gel Method) using polyvinyl alcohol (PVA) as chelating agent. These materials are annealed from 500oC -1000°C with a step size of 100oC temperature. The multifunctional properties of the prepared materials have been studied in view of their structural, morphological, optical, magnetic, and mechanical characteristics. X-ray diffraction (XRD) studies have shown that ZnO (zinc oxide) nano powders are crystallized in the Wurtzite hexagonal structure, and the structural parameters have been determined. Transmission Electron Microscopy (TEM) study conducted on a sample annealed at 900°C revealed nanoparticles size as~22nm. Spherical nanoparticles with irregular particle morphology was observed from SEM (Scanning Electron Microscopy) images. Energy dispersive spectroscopy (EDS) accorded the existence of elementary components of the prepared samples. The characteristic peaks of ZnO are evident from Fourier transform infrared spectroscopy (FTIR) study. The bandgap energies from UV-Visible studies levied to decrease from 3.31 eV to 3.13 eV with annealing temperatures. Near band edge emission exhibited redshift from Photoluminescence (PL) study with the increase in annealing temperature. The Dilute Magnetic Semiconductor (DMS) nature was observed on the studied materials, making them promising materials for multifunctional spin-based applications. The study of Mechanical properties suggests that these materials may find applications as cutting fluids, nanofillers and nanolubricant additives.