We report the errors in the evaluation of the surface plasmon resonance of gold nanorods by three classical approaches: the Gans model, the Discrete Dipole Approximation and the Surface Integral method. Using these methods, which are based on the propagation of an electromagnetic wave through a composite medium with different refractive indices, might result in an inaccurate prediction of absorption maxima. For test samples of nanorods prepared by a seed-mediated method, whose homogeneity and quality were also fully demonstrated in this study, the mismatches in the wavelengths of absorption maxima Δλ max j j between experimental and theoretical data were observed to be greater than 50 nm. In general, the observed surface plasmon resonances exhibit two distinctive bands corresponding to the transverse and longitudinal modes. The weak transverse mode was located in the region from 510 to 518 nm and varied slightly with the aspect ratio of the rods. In contrast, the longitudinal mode showed a strong dependence on aspect ratio and ranged from 658 to 768 nm. We demonstrated that the mismatches may be sufficiently reduced if the interdependence between these two modes is taken into account.
This study presents results on crystal structure and phase transition in La 1¹y Ce y Fe 11.44 Si 1.56 (y = 0.1 and 0.3) compounds. All the samples were prepared by using arc-melting method in argon atmosphere. The effect of temperature was studied by X-ray diffraction method. As shown, the compounds possess clear NaZn 13 -type cubic phase with ferromagnetic spin arrangement of Fe atoms. There reveals a sudden change of lattice constants at 195 K (y = 0.1) and 175 K (y = 0.3) which corresponds to type 1 phase transition.
Low field magneto-caloric response is important for application. We present here the results of a study on crystal structure and magnetic properties of rare-earth doped compounds La 0.8 R 0.2 (Fe 0.88 Si 0.12 ) 13 (R = Y, Ho and Yb). All samples were prepared by using arc-melting method in argon atmosphere. The lattices revealed by X-ray diffraction method show a well-defined NaZn 13 -type structure with small amounts of ¡-Fe phase. The dependence of magnetization on temperature M(T) and on field M(H) curves were recorded. The magnetic entropy change ¹¦S m and cooling powers (RCP) of compounds were estimated. The results show considerable better magneto-caloric responses of doped compounds in comparison with that of the undoped compound.
: The saturated magnetization in 20% substituted La0.8R0.2(Fe0.88Si0.12)13 (R = Sm, Tb) magneto-caloric alloys is discussed in this work. The measurements were taken up to 70 kOe (7 Tesla) to detect the saturation of magnetic moments. As reported recently [Mat. Trans. 59(7) (2018) 1068], these compounds show a large variation of magnetic entropies at low field variation (~ 1.5 T), which associate with the large relative cooling efficiency (RCP) of 52 (for Tb-doped) and 102 J/kg (for Sm-doped) even at low effective DH of ~ 15 kOe. We re-detected the effective range of field variation DH and recognized that the effective DH ~ 5 kOe which is much lower than the value of other magneto-caloric compounds and is excellent for application of Sm-doped compound in modern cooling devices.
Keywords: Magnetic, alloys, LaFe13, phase transition, rare-earth.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.