Tuning of the band gap and dielectric loss factor by Mn doping of Zn1-xMnxO nanoparticles.

This study explored the structural, optical, and dielectric properties of Pure and Mn+2 doped ZnO nano-particles (Zn1-xMnxO) with x ≥ 20%, synthesized by co-precipitation method followed by annealing at 4500C. Different characterization techniques were conducted to characterize the as-prepared nano-particles. X-ray Diffraction analysis of the pure and Mn+2 doped presented a hexagonal wurtzite structure and a decreased crystallite size with increasing doping concentration. Morphological analysis from SEM revealed finely dispersed spherical nanoparticles with particle size of 40-50 nm. Compositional analysis from EDX confirmed the incorporation of Mn+2ions in ZnO structure. The Results of UV spectroscopy showed that changing the doping concentration affects the band gap, and a red shift is observed as the doping concentration is increased. The band gap changes from 3.3 to 2.75 eV. Dielectric measurements exhibited decrease in the relative permittivity, dielectric loss factor and ac conductivity by increasing Mn concentration.

Unsteady hybrid nanofluid ([Formula: see text], MWCNTs/blood) flow between two rotating stretchable disks with chemical reaction and activation energy under the influence of convective boundaries.

Hybrid nanofluids are extensively analyzed in recent studies due to their better performance in numerous areas such as heat and mass transfer enhancement, biological fluid movement, medical equipment, heat exchangers, electronic cooling and automotive industry. In current study the nanoparticle concentration utilized is much important in biomedical industry. Major applications include drug delivery, radio-pharmaceuticals, centrifuging blood to obtain red blood cells and plasma, medical implants, onco therapeutics and photo thermal cancer therapy. In this regard, the primary focus of this study is to simulate a blood based unsteady hybrid nanofluid flow between two rotating, stretching disks and convective boundaries. The two nanoparticles in this study are uranium dioxide [Formula: see text] and multi-walled carbon nanotubes MWCNTs. The hybrid nanofluid is under the influence of magnetohydrodynamic effects and chemical reaction with activation energy. The governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) using suitable similarity transform. Homotopy analysis method is used to solve the non-linear system of ODEs and [Formula: see text]-curves are plotted to find suitable region of [Formula: see text] for convergent series solution. Velocity profile is examined for axial, radial and tangential direction against various fluid parameters. Temperature and concentration profiles are analyzed for both convective and non-convective cases. It is observed that convective boundaries result in elevated temperature when compared with non-convective case. Moreover, skin friction, heat and mass transfer rates are also examined with respect to changing volume fraction [Formula: see text].The results revealed that skin friction and rate of heat transfer increases with increase in volume fraction of both nanoparticles [Formula: see text] and MWCNTs while the mass transfer rate depicts contrasting behavior.