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A series of novel lead-free tungsten bronze-structured Ba4(Dy2-xBix)Fe2Nb8O30 (x = 0, 0.05, 0.1, 0.15, 0.2 and 0.25) were formulated by the traditional high-temperature solid-state method using ball milling for 30 hrs and calcined at 1115°C. The structural property was investigated using X-ray diffraction and Fourier transform infrared spectroscopy. The tetragonal structure with the P4bm space group was confirmed from Rietveld analysis. The scanning electron micrograph shows a uniform distribution of different-shaped grains with less porosity. The UV-vis analysis shows that the materials have band gaps in the range of 2.45–2.51 eV which makes them useful for photocatalytic applications. From photoluminescence analysis, it is confirmed that the samples can be used as violate-/blue light-emitting diodes. The impedance of the materials falls off with the rise in temperature showing their negative temperature coefficient behaviour. The variation of polarization with an electric field confirms the ferroelectric nature of the samples. [ABSTRACT FROM AUTHOR]

Organic spintronics (OS), which focuses on utilizing the spin degree of freedom in organic materials, has been a fascinating topic because of its technological aspects and future applications. In-plane uniaxial magnetic anisotropy (UMA) is becoming increasingly important in the rapidly developing field of OS. In this study, Cobalt (Co) films were deposited with varying thicknesses on the Tris (8-hydroxyquinolinato) aluminium (Alq3) layer to investigate the evolution of magnetism and UMA. Magnetic measurements and simultaneous domain imaging have been done using the magneto-optic Kerr effect by varying the azimuthal angle between the easy axis of magnetization and the applied magnetic field. It was discovered that the bilayer exhibits a well-defined UMA in the film plane upon forming a continuous Co film with a thickness of around 10 nm. Structural and morphological properties of all the Co/Alq3 bilayers were studied using grazing-incidence small-angle X-ray scattering and wide-angle X-ray scattering measurements at synchrotron radiation source, P03 beamline PETRA-III, Germany. The combined analysis revealed that in contrast to the inorganic magnetic polycrystalline thin films, where the UMA originates mainly due to the stress, the origin of UMA in Co/Alq3 is attributed to the magnetocrystalline anisotropy caused by c-axis (Co (002)) preferential orientation. The surface free energy of Alq3 is less than that of Co; therefore, the growth of Co starts with island formation, which coalescences with increasing thickness. The observed structure orientation may be attributed to minimizing the magnetoelastic energies due to coalescence known as the zipping effect. The absence of UMA in films with lower thickness film (~5 nm) is understood in terms of random short-range stress caused by isotropic pinning due to the diffused interface. [ABSTRACT FROM AUTHOR]

A series of novel lead free tungsten bronze (T-B) structured Ba4(La2-xBix)Fe2Nb8O30(x = 0, 0.05, 0.1, 0.15, 0.2, and 0.25) were formulated by traditional high temperature solid-state method and calcined at 1200 °C. The structural property was investigated by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Tetragonal structure was confirmed from Rietveld analysis. The scanning electron micrograph (SEM) shows uniform distribution of rod-shaped grains with less porosity. The UV–vis analysis shows that the materials have band gaps in the range 2.17–2.29 eV which makes them useful for photocatalytic applications. The dielectric measurement of the samples was carried out in a broad range of frequency as well as temperature. The impedance of the materials falling off with the rise in temperature showing their negative temperature coefficient (NTCR) behavior. The variation of polarization with electric field confirms the ferroelectric nature of the samples. [ABSTRACT FROM AUTHOR]