ABSTRACT
We report, for the first time, correlations between crystal structure, microstructure and magnetofunctional response in directionally solidified [110]-textured Fe83Ga17Erx (0 < x < 1.2) alloys. The morphology of the doped samples consists of columnar grains, mainly composed of a matrix phase and precipitates of a secondary phase deposited along the grain boundary region. An enhancement of more than ~275% from ~45 to 170 ppm is observed in the saturation magnetostriction value (λs) of Fe83Ga17Erx alloys with the introduction of small amounts of Er. Moreover, it was noted that the low field derivative of magnetostriction with respect to an applied magnetic field (i.e., dλs/dHapp for Happ up to 1000 Oe) increases by ~230% with Er doping (dλs/dHapp,FeGa= 0.045 ppm/Oe; dλs/dHapp,FeGaEr= 0.15 ppm/Oe). The enhanced magnetostrictive response of the Fe83Ga17Erx alloys is ascribed to an amalgamation of microstructural and electronic factors, namely: (i) improved grain orientation and local strain effects due to deposition of Er in the intergranular region; and (ii) strong local magnetocrystalline anisotropy, due to the highly anisotropic localized nature of the 4f electronic charge distribution of the Er atom. Overall, this work provides guidelines for further improving galfenol-based materials systems for diverse applications in the power and energy sector.
ABSTRACT
Epidemiological and laboratory investigations have shown that toluene and styrene are toxic compounds that lead to impairment of the nervous system. To quantitate toluene and styrene in biological samples, liquid-liquid phase, headspace (HS), and solid-phase microextraction (SPME) methods are generally used. Most of these methods are not sensitive enough for applications involving small sample volumes. Here, we present a method for quantitative analysis of low concentrations of styrene and toluene in very small volumes of biological samples using HS-SPME and gas chromatography (GC) equipped with a flame-ionization detector. The method was developed by optimizing operating parameters that affect the HS-SPME-GC process [i.e., desorption time (30 s), depth of the fiber in the GC injection port (3.7 cm), adsorption time (4 min), and adsorption temperature (room temperature)]. It has a wide range of linearity (0.5-500 ng/10 microL), high precision (coefficient of variation < 5%), good accuracy (deviation < 11%), and low detection limits of 0.13 and 0.08 ng/10 microL for styrene and toluene in serum, respectively. This analytical technique can be applied to the estimation of styrene and toluene in small volumes of biological fluids (blood, serum, and perilymph) and tissues of low lipid content (cochlea).
