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Manganese decorated Multiwalled carbon nanotubes were synthesized through a simple solvo thermal method. The surface morphology and structural analyses of the MnO2 doped MCNT have performed by Transmission electron microscope (TEM), Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). Morphological characterization reveals that three-dimensional hierarchy architecture built with a highly porous layer consisting of interconnected MnO2 uniformly coated on the CNT surface. The XRD and EDS results confirmed that the prepared samples containing MnO2/CNT in pure form without impurities. It also reveals that birnessite-type MnO2 is formed through the solvo thermal synthesis. The Optical properties of the prepared samples were examined by UV-visible spectrometer and Fourier transform spectroscopy. The UV-vis spectra of the nanoparticles indicate a decrease in the band gap from 1.037 to 0.999 eV. The results reveal the band gap shrinkage associated with Mn concentration more at high temperature phase and crystalline behavior. The composition of the prepared samples were characterized using Energy dispersive spectroscopy (EDS).

Polyvinyl alcohol (PVA)-blended spinel phase NiNdxFe2-xO4 nanoferrites were successfully prepared with a different composition (x = 0.01, 0.03, 0.05, 0.07, and 0.09). The spinel cubic structure was revealed from X-ray diffraction pattern. These nanoferrites showed insulating behavior with an enhanced energy bandgap when compared with PVA-unblended nanoferrites. The obtained dielectric loss and real and complex dielectric constants were in the microwave region (frequency ∼2.9–5.95 GHz). Pseudocapacitance and resistive behavior were explored from impedance analysis. The magnetization hysteresis plot of nanoferrites showed a soft ferromagnetic nature. It was found that reduction in saturation magnetization of NiNdxFe2-xO4 nanoferrites obtained by PVA doping has the strong microwave absorption capacity.

The Gadolinium substituted LaCrO3 isovalent perovskite was investigated in the present study. The samples of La1-xGdxCrO3 (x = 0, 0.025, 0.05, 0.10, 0.15 and 0.20) were prepared employing solid state reaction method. The X-Ray Diffraction (XRD) patterns confirmed that the prepared samples have orthorhombic structure with pnma space group at room temperature. The crystalline size of the samples is 98, 89, 76, 72, 60 and 55 nm respectively for the composition x = 0, 0.025, 0.05, 0.10, 0.15 and 0.20 and the same is decreasing with an increase in substitution of Gd in the samples. The scanning electron microscope images of the samples have spherical like morphology with a particle size of 150, 131, 129, 120, 116 and 94 nm for the composition x = 0, 0.025, 0.05, 0.10, 0.15 and 0.20 respectively. In-situ ultrasonic measurements were made over a wide range of temperature from 300 to 700 K to determine structural transition. The measured temperature dependent ultrasonic parameters are used to explore the structural phase transition from orthorhombic to rhombohedral phase in the prepared sample at high temperatures.

On-line ultrasonic measurements were taken on La 0.7 Sr 0.3 Cu x Mn 1−x O 3 polycrystalline perovskite materials (with x = 0.05, 0.10, and 0.15), which were prepared using the solid-state reaction technique. X-ray diffraction patterns of the samples confirmed the rhombohedral structure with R3c space group. The obtained X-ray spectra from the energy-dispersive analysis confirmed the elemental composition of the prepared samples. Scanning electron microscopy was used to determine the size of the particles in the samples. The substitution of copper in the Mn site was found to affect the Mn 3+ /Mn 4+ ratio and the density of the charge carriers. The substitution caused an additional disorder that weakened the double-exchange (DE) interaction and reduced the ferromagnetic order. The temperature dependence of the elastic constants derived from the ultrasonic velocities revealed interesting features in the samples. The elastic constants indicated a short-range ferromagnetic to paramagnetic transition at temperatures ( T C ) of 358, 341 and 328 K for the samples with compositions ( x ) of 0.05, 0.10 and 0.15, respectively.

R.1-xSrxMnO3 (R-Rare earth elements such as La, Pr, Sm and Nd) perovskite materials were prepared employing solid state reaction technique. On-line measurement of ultrasonic longitudinal velocity was carried out on the prepared perovskites over a wide range of temperature at a fundamental frequency of 5 MHz employing through transmission method. The phase transition temperature is explored based on the variation in observed anomaly in ultrasonic velocity. The obtained transition width and height at Curie temperature (i.e., transition from ferro to para magnetic phase) in the measured ultrasonic velocity were used to explore the physiochemical properties of the perovskites. The transition width and height of anomalous peak in measured ultrasonic velocity are also correlated with the ionic radius of the trivalent element. The results reveal that an increase in ionic radius of the trivalent elements leads to a decrease in double exchange interaction.

In this paper, the application of the photo-acoustic method to study the thermal properties of modified 9Cr-1Mo Steel is described. The photo-acoustic measurements are carried out for the thermal properties of modified 9Cr-1Mo steel samples of various thicknesses. The theoretical basis for quantitative measurements is discussed, together with the advantages and limitations of these methods as compared with conventional measurements.

The ornamental granite stone-processing industries of Tamilnadu state produce tons of fine powder wastes during sawing and polishing. It is a non-biodegradable waste that can be easily inhaled by human being and animals and is also harmful to the environment. The main objective of this study is to investigate experimentally the suitability of granite powder (GP) waste as a substitute material for fine/natural aggregate in concrete production. The physical and chemical characterization of the GP waste was also addressed. The experimental parameter was the percentage of granite powder substitution. The cubes and cylinders were prepared using 0%, 5%, 10%, 15%, 20% and 25% of fine/natural aggregate substituted by GP waste. To understand fully the influence of GP waste on the behavior of concrete, several tests such as density, slump cone, split tensile strength, flexural strength; ultra sonic pulse velocity (UPV) and compressive strength tests were performed. The Young’s modulus of elasticity of the concrete was also determined. The GP waste exhibited a very high specific surface value of about 340kg/m2 and chemical analysis results showed that the examined material contains about 77% of silica (SiO2). Experimental results revealed that the rough texture and high specific area of the GP waste significantly decreased the workability of the concrete especially for the substitution level of 20% and 25%. The obtained test results show that the substitution of GP waste up to 15% does not affect the mechanical and fresh concrete properties of the concrete and it was recommended that the replacement of natural sand by GP waste up to 15% of any formulation would be favorable for concrete making.

A detailed analysis on the depth profiles of 30 keV H+ ion implanted n-GaAs for various doses from 1014 to 1017 cm-2 was carried by using Secondary ion mass spectrometry (SIMS), to identify the buried amorphous layer. The results are correlated with Raman and XRD strain parameter studies. Various thermal parameters are computed for the 30 keV H+ ion implanted n-GaAs and SIMS study reported for the first time.

In this paper, the application of photoacoustic methods to study thermal properties of Al-Li alloy is described. The photoacoustic measurements are carried out for thermal properties on Al-Li alloy and studied for various thicknesses. The theoretical basis for quantitative measurements is discussed together with the advantages and limitations of these methods as compared with conventional measurements. Applications to spectroscopic and depth-profile analysis and also to thermal property measurements in Al-Li samples heat-treated at 755K per hour and annealed at 505K are discussed. The results are compared with literature values, and discussed.

The nuclear material, Zircaloy-2 is studied here by photoacoustics and the results are correlated with ultrasonic measurements and metallographic microstructures. Precipitation of hard intermetalics and formation of α-martensite, due to thermal aging are also explained through photoacoustic studies.

Alloy D9 is a candidate material for core components of fast breeder reactors. This alloy has been 20% cold worked and thermally aged at 1073 K for different time durations and their thermal properties have been studied using photoacoustic (PA) measurements. The results of the PA measurements have been correlated well with the ultrasonic velocity and hardness measurements.

Zircaloy-2, an useful nuclear material is studied here by photoacoustics to correlate with the measurements of X-rays. The microstructure variations observed in X-rays could be explained on the basis of thermal diffusivity measured by photoacoustics technique.

The optical and thermal properties of the mixed semiconducting alloy, Sn1-xGexTe, is studied by photo acoustics, for various Ge concentrations and phase transition for a particular concentration is also studied by the same method. The results are compared with the available literature values and discussed.