A short note on Magnetized Black-hole in Non-linear Electrodynamics

We have analyzed the thermodynamic properties of magnetized black-hole in the background of non-linear electrodynamics with two parameters $\beta$ and $\gamma$. We have studied the Bekenstein-Hawking entropy, Hawking temperature, specific heats in two-dimesional surface plots as a function of event horizon ($r_{+}$) and $\gamma$. We showed the variation profiles of the above thermodynamic parameters for $\gamma$ [$0 \rightarrow 1$]. We identified regions of parameters for the possible phase-transitions and the stability of the black-holes.Comment: 6 pages, 8 figure

Nearly Static Magnetized Kerr Black-hole in Non-linear Electrodynamics

We have analyzed the thermodynamics of slowly rotating magnetized Kerr black-hole, with typical spin parameter $a\le 0.1$ (nearly static) in the background of non-linear electrodynamics. In particular we have studied the Bekenstein-Hawking entropy, Hawking temperature, angular momentum, specific heats and identified regions of parameters for possible phase-transitions. It turns out that once the stability lost the black-hole never come back to its original stable position.Comment: 9pages, 12 figure

Magnetoelectric Coupling in Metglas/BaTiO 3 /Metglas Lead-Free Magnetoelectric Composites

Abstract We report the magnetoelectric (ME) coupling in ME composites composed of NiFe 2 O 4 (NFO) or metglas as magnetostrictive phases and BaTiO 3 (BTO) as piezoelectric phase, targeting lead free magetnic field sensors. NFO and BTO phases were synthesized by solid state sintering method and further characterized by using XRD and FESEM techniques. The P-E hysteresis curve shows good ferroelectric behavior with saturation polarization of P s = 15.87 C/cm 2 and coercive electric field of 130 kV/cm. The ME response was characterized as a function of dc magnetic field at a fixed frequency. The transverse ME voltage coefficient, α ME31 shows 2 times larger magnitude than that of longitudinal ME voltage coefficient, α ME31 . The maximum α ME31 of 37 mV/cm•Oe (@H dc = 250 Oe) is observed for NFO/BTO/NFO ME composites with thickness ratio of t m /t p = 1.0. The ME coupling is further enhanced by replacing NFO layers by highly magnetostrictive metglas layers. Metglas/BTO/metglas laminates show large α ME31 value of 81 mV/cm•Oe at relatively lower H dc of 145 Oe. The present laminates can offer promising opportunities of engineering environmental friendly ME laminate for applications in ME devices such as energy harvester and magnetic field sensors

Dielectric and magneto-electric behavior of (x) Co0.8Mn0.2Fe2O4 and (1−x) PbZr0.52Ti0.48O3 composites

The multiferroics with ferroelectric (FE) and ferromagnetic (FM) phases (x) [Co0.8Mn0.2Fe2O4] + (1−x) [PbZr0.52Ti0.48O3] composite samples with x = 0.25, 0.50 and 0.75, were prepared by ceramic route. X-ray diffraction (XRD) patterns of as-prepared samples exhibit the presence of lead zirconate titanate PbZr0.52Ti0.48O3 (PZT) and Co0.8Mn0.2Fe2O4 (CMFO) phases in the PZT-CMFO composites. The values of grain size were found to be decreased in the range of 680–390 nm with increasing the ferrite contents from x = 0.25 to 0.75. The temperature dependent dc resistivity (ρ) of the composites was reduced with increasing x contents. The values of dielectric constant (ε′) 7x103-20 x103 were found to be increased at 30 Hz frequency. The variations in (ε′) with frequency (20 Hz -1MHz) were caused by interfacial polarization occurred in the composites. The changes in AC conductivity (σac) of composite samples were found to be increased with the frequency. The higher value of magneto-electric (ME) coefficient (0.641μv/cm Oe) was obtained for x = 0.25 of composite sample. © 2021 Elsevier B.V.1

Structural, optical and (photo)electrochemical properties of electrodeposited Cd-Zn-Se thin films

413-420<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Cadmium zinc selenide (Cd-Zn-Se) thin films have been prepared onto stainless steel and fluorine doped tin oxide (FTO) coated glass substrates by the electrodeposition technique. The structural, optical and photoelectrochemical properties of the films have been studied. The X-ray diffraction studies reveal that the Cd1-xZnxSe(0≤ x ≤ 1) films are polycrystalline. It has also been found that the films deposited with x = 0.2 and 0.7, show relatively higher extent of single crystallinity than those deposited with other compositions. The estimated direct optical gaps are found to be in the range of 1.9 to 2.5 eV and it's value increases with an increase in the value of x. Photoelectrochemical characterization carried out using ferriferrocyanide electrolyte shows better performance for the films deposited with x = 0.2 and 0.7 compositions.</span

Mössbauer, Raman, and magnetoresistance study of aluminum-based iron oxide thin films

Thin films of Al-based hematite iron oxide were synthesized by spray pyrolysis in aqueous medium onto the glass microslides. The compact and homogeneous distribution of grains (spindle-shaped hematite nanostructures) with varying sizes has been observed in surface morphological studies. The room temperature Mössbauer study has been carried out to monitor the local environment around Fe cations and valence state of Fe ions. Mössbauer and micro-Raman (low temperature) results suggest that oxygen vacancies cause cation redistribution between the interstitial sites resulting in magnetic ordering. The variation of magnetoresistance in low magnetic field (&#62;3 kOe) is also reported

Gas Sensing of Fluorine Doped Tin Oxide Thin Films Prepared by Spray Pyrolysis

Fluorine doped tin oxide (F: SnO2) films have been prepared onto the amorphous glass substrates by a spray pyrolysis. XRD studies reveal that the material deposited is polycrystalline SnO2 and have tetragonal structure. It is observed that films are highly orientated along (200) direction. The direct optical band gap energy for the F: SnO2 films are found to be 4.15 eV. Gas sensing properties of the sensor were checked against combustible gases like H2, CO2 CO, C3H8, CH4.The H2 sensitivity of the F-doped SnO2 sensor was found to be increased. The increase in the sensitivity is discussed in terms of increased resistivity and reduced permeation of gaseous oxygen into the underlying sensing layer due to the surface modification of the sensor

Investigation of structural, optical and luminescent properties of sprayed N-doped zinc oxide thin films

N-doped ZnO (NZO) thin films are synthesized via spray pyrolysis technique in aqueous medium treating zinc acetate and N,N-dimethylformamide as precursors. Influence of N doping on structural, optical and luminescence properties have been investigated. Films are nanocrystalline having hexagonal crystal structure. Raman analysis depicts an existence of N-Zn-O structure in NZO thin film. XPS spectrum of N1s shows the 400 eV peak terminally bonded, well screened molecular nitrogen (gamma-N-2). Lowest direct band gap of 3.17 eV has been observed for 10 at% NZO thin film. The UV, blue, and green deep-level emissions in photoluminescence of NZO films are due to Zn interstitials and O vacancies