We present a detailed study of the magnetic and crystal-field properties of the hexagonal Kondo lattice YbCu 3 Al 2 , using 170 Yb Mössbauer spectroscopy in the temperature range 0.1 K-50 K. L III -edge x-ray absorption spectra at 10 K and 300 K were also obtained; they indicate that the Yb ion is very close to trivalent over the whole temperature range. In the antiferromagnetic phase, the thermal variation of the Yb 3+ spontaneous moment has been measured and the derived transition temperature (T N = 1.95 K) is in agreement with previous specific heat and magnetic data. In the paramagnetic phase, the two components g z and g ⊥ of the g-tensor of the Yb 3+ ground crystal-field doublet have been measured. These g-values cannot be accounted for by a crystal-field-only model, and we interpret this in terms of a Kondo reduction of the paramagnetism (T > T N ) and of the spontaneous moment (T < T N ), with a Kondo temperature T K 2.3 K. In addition, the spectra in the antiferromagnetic phase show inhomogeneous broadenings due to the presence of random distortions with respect to the hexagonal Yb site symmetry, and, close to T N , dynamical effects are clearly evident and allow the Yb 3+ fluctuation frequency to be measured in the magnetically ordered phase.
A method for quantifying the nanomechanics of nanomaterials was developed using a nanoprobe manipulator fitted into a transmission electron microscope. Apparent Young’s moduli of various carbon nanotubes (CNTs) were measured using this method. The apparent Young’s modulus of an arc-grown CNT is as large as approximately 3.3TPa, which is close to the theoretical Young’s modulus (5.5TPa) of the single-walled CNT simulated using molecular dynamics. The relationship between the apparent Young’s modulus and the crystallinity of CNTs is demonstrated using the crystallinity parameter ID∕IG derived by Raman spectroscopic analysis. The apparent Young’s modulus is higher for better crystallinity of CNT.
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