Three terminal capacitance technique for magnetostriction and thermal expansion measurements

An instrument has been constructed to measure a large range of magnetostriction and thermal expansion between room temperature and 4 K in a superconductive split-coil magnet, that allows investigation in magnetic fields up to 12 T. The very small bulk samples (up to 1 mm in size) as well as big ones (up to 13 mm) of the irregular form can be measured. The possibility of magnetostriction investigation in thin films is shown. A general account is given of both electrical and the mechanical aspects of the design of capacitance cell and their associated electronic circuitry. A simple lever device is proposed to increase the sensitivity twice. The resulting obtained sensitivity can be 0.5 Angstrom. The performance of the technique is illustrated by some preliminary measurements of the magnetostriction of superconducting MgB2, thermal expansion of (La0.8Ba0.2)0.93MnO3 single crystal and magnetoelastic behavior of the Ni/Si(111) and La0.7Sr0.3CoO3/SAT0.7CAT0.1LA0.2(001) cantilevers.Comment: 6 pages, 6 figures, journal pape

AMORPHOUS RIBBONS OF LiNbO_3 AND PbTiO_3

By a roller quenching technique amorphous ribbons of LiNbO_3 and PbTiO_3 were obtained. These ribbons were examined by electron diffraction as well as by X-ray diffraction experiments, resulting in obtaining them in amorphous state

Saturation Magnetostriction and Volume Magnetostriction of Amorphous Ribbons Based on Fe-Ni and Fe-Co

The saturation magnetostriction and the forced volume magnetostriction of Fe-Ni and Fe-Co amorphous ribbons were measured from 77°K to room temperature by a three terminal capacitance method. It was found that the magnetostriction was nearly isotropic. In Fe-Ni amorphous system, the saturation λ_s and the volume magnetostriction constants δω/δH decreased monotonously with the increase of Ni concentration from 31×10^ and 21×10^/Oe respectively for Fe_P_C_ to 15×10^ and 7×10^/Oe respectively for Fe_Ni_P_C_. The temperature dependence of the saturation magnetostriction was not simple decreasing function of the temperature. In Fe-Co system, there was a remarkable change of the sign of the magnetostriction nearly equal to Fe_Co_Si_B_

Giant ΔE Effect and Magnetomechanical Coupling Factor in Amorphous Fe80P13C7 Ribbons

The magnetomechanical coupling factor k, the Young\u27s modulus E and the ΔE effect as a function of bias field were measured by a mechanical resonance method of amorphous Fe80P13C7 ribbons which were annealed at different temperatures in a magnetic field. In the ribbon which was annealed at 350℃ for 20 minutes, a remarkably large coupling factor k was found in the bias field 5 Oe to be 0.53, which was almost the same as the value of the high magnetostrictive rare earth-Fe2. The ΔE effect increased with the increase of the bias field, took a gigantic value 0.8 at about 5 Oe and then decreased monotonically with the increase of the bias field. The ΔE effect is known to correspond to a change in sound velocity, so that the change of the sound velocity was also observed as a function of the frequency from 100 kHz to 1MHz in a delay line using the ribbons

Zero Magnetostriction and Extremely Low Residual Magnetic Loss in Fe-Co Amorphous Ribbons

application/pdfThe initial permeability μ_i, the loss factor tan δ, and the inverse quality factor tan δ/μ_i of Fe_5Co_Si_B_ ribbons 35 μm, 30 μm, 25 μm and 21 μm in thickness were measured with a Maxwell Bridge from room temperature to 140℃ in the high-frequency region from 3 kHz to 500 kHz. The initial permeability of the ribbon 21 μm in thickness was about 10, 600 at 3 kHz and 4300 at 500 kHz. The residual loss coefficient C_1 and the hysteresis loss coefficient h_1 were extremely low, about 8×10^ and 60 (cm/A), respectively. In the high-frequency region, the eddy current loss term increases with the square of the thickness of the ribbons and plays the most important part of all the magnetic losses.紀要類(bulletin)70514 bytesdepartmental bulletin pape

Observation of the Magnetostriction in Ferromagnetic Amorphous Thin Ribbons

The first observation of the magnetostriction of the amorphous thin ribbons was made at room temperature, and it was found that in Fe_P_C_, the saturation magnetostriction λ in the plane was 18.5×10^ which was several times bigger than that of bulk iron in the polycrystalline state

Phase measurement interferometric microscopy of stacked fishnet metamaterials

SPIE OPTO, 2012, San Francisco, California, Unitd StatesT. Matsui, A. Miura, T. Nomura, H. Fujikawa, K. Sato, N. Ikeda, D. Tsuya, M. Ochiai, Y. Sugimoto, H. T. Miyazaki, M. Ozaki, M. Hangyo, and K. Asakawa "Phase measurement interferometric microscopy of stacked fishnet metamaterials", Proc. SPIE 8269, Photonic and Phononic Properties of Engineered Nanostructures II, 82692P (22 February 2012) DOI: https://doi.org/10.1117/12.90724

Tribological properties of room temperature fluorinated graphite heat-treated under fluorine atmosphere

This work is concerned with the study of the tribologic properties of room temperature fluorinated graphite heat-treated under fluorine atmosphere. The fluorinated compounds all present good intrinsic friction properties (friction coefficient in the range 0.05–0.09). The tribologic performances are optimized if the materials present remaining graphitic domains (influenced by the presence of intercalated fluorinated species) whereas the perfluorinated compounds, where the fluorocarbon layers are corrugated (armchair configuration of the saturated carbon rings) present higher friction coefficients. Raman analyses reveal that the friction process induces severe changes in the materials structure especially the partial re-building of graphitic domains in the case of perfluorinated compounds which explains the improvement of μ during the friction tests for these last materials