Electrical properties of fullerenol C60(OH)10/Au interface

Electrical properties of the C60(OH)10/Au contact have been studied by measuring its current-voltage characteristics in the temperature range of 300–500 K. The Schottky barrier of the C60(OH)10/Au contact was confirmed to be 0.70±0.020.70±0.02 eV from Arrhenius plots of the current-voltage characteristics measured at various bias voltages as well as various preparation conditions of the C60(OH)10 material. Significant effect of the applied electric field on the barrier height has not been observed in the range of 0.1–2.0 MVm−10.1–2.0 MVm−1. The effects of both the charge transfer from C60 cage to OH groups and the crystallinity of the C60(OH)10 material on the Schottky barrier were discussed on the basis of x-ray photoemission spectroscopy and x-ray diffraction analyses

Measurement of Excited States of Sb Impurity in Si by Traveling-Wave Method

The ground and excited states of Sb atom in Si, 1s (A 1), 1s (T 2), 1s (E), and 2p0, were measured by using a traveling-wave method. The Sb-doped Si crystal with donor concentration of 2 × 1015 cm−3 was placed the distance of 5 μm above a piezoelectric crystal in the fringe field of a surface acoustic wave. The free electrons excited from the bound states of the Sb atom are drifted by the traveling-wave, and thus lose their energy as the Joule heat through lattice and ion scattering processes. A strong temperature-dependent energy loss of the traveling-wave can be observed at temperatures below 200 K. The values of the bound states of the Sb atom can be characterized by using the Arrhenius plot for thermal activation process of the electrons in the bound states. The measurements were carried out at two frequencies of the traveling-wave, 50 MHz and 200 MHz. At the frequency of 50 MHz, the dielectric properties of the Si crystal are governed by dopant polarization but by electronic polarization at 200 MHz. We found that measurement accuracy of the bound states depends mainly on the electron mobility and the dielectric constant of the Si crystal, which are sensitive to the frequency and strength of the traveling-wave as well as electronic polarization properties of the Si crystal

LiB electrode ageing observed from PVdF binder

Ageing behaviors of the positive electrode of lithium ion battery are characterized by measuring mechanical properties of the electrode reeds, such as resonance frequency and internal friction, as a function of temperature. In the measurements of the electrode reeds with a sandwich structure of active material film and current collector of Al foil, two thermally-activated relaxation processes can be observed on the polyvinylidene difluoride binder in the active material film. Namely, a surface-related relaxation at ~150 K and a relaxation corresponding to the β-phase transition at ~240 K in the polymer binder can be observed at high signal/noise ratio. The resonance frequency decreases and the internal friction increases after charge/discharge cycling. The changes in activation energies of the relaxation processes also indicate that the measurement of mechanical properties of the positive electrode is an effective method for characterizing ageing behaviors of the positive electrode as a whole

Carrier transport properties of nanocrystalline Er3N@C80

Electrical transport properties of the nanocrystalline Er3N@C80 with fcc crystal structure were characterized by measuring both temperature-dependent d.c. conductance and a.c. impedance. The results showed that the Er3N@C80 sample has characteristics of n-type semiconductor and an electron affinity larger than work function of gold metal. The Er3N@C80/Au interface has an ohmic contact behavior and the contact resistance was very small as compared with bulk resistance of the Er3N@C80 sample. The charge carriers in the sample were thermally excited from various trapped levels and both acoustic phonon and ionic scatterings become a dominant process in different temperature regions, respectively. At temperatures below 250 K, the activation energy of the trapped carrier was estimated to be 35.5 meV, and the ionic scattering was a dominant mechanism. On the other hand, at temperatures above 350 K, the activation energy was reduced to 15.9 meV, and the acoustic phonon scattering was a dominant mechanism. In addition, a polarization effect from the charge carrier was observed at low frequencies below 2.0 MHz, and the relative intrinsic permittivity of the Er3N@C80 nanocrystalline lattice was estimated to be 4.6 at frequency of 5.0 MHz

Schottkey barrier measurement of nanocrystalline Lu3N@ C80/Au contac

Electrical and structural properties of nanocrystalline solids of C80 fullerene encapsulated with a Lu3N cluster, Lu3N@C80, have been studied by measuring x-ray photoemission spectra, x-ray diffraction, and current-voltage characteristics of the Lu3N@C80/Au Schottky contact in the temperature range of 300 - 500 K. The nanocrystalline solid sample of Lu3N@C80 fullerene consists of grains characterized with an fcc structure and those grains become larger in size after pressing the powder sample at 1.25 GPa. The current-voltage characteristics measured at various temperatures showed that there are no significant dependences on both the Schottky barrier and the carrier mobility on electric field. The Schottky barrier of the Lu3N@C80/Au contact is determined to be 0.71 ± 0.04 eV

Electric field induced effects in Y3N@[C80]6- anionic solid

By measuring the i−vi−v characteristics of Y3N@[C80]6− anionic solid at various temperatures and electric field strengths, four conducting phases with i∝vi∝v , i∝v2i∝v2 with low resistance, i∝v4i∝v4 and i∝v2i∝v2 with high resistance were observed. First, at temperatures below 100 K and field strengths below 30 Vcm−1Vcm−1 , the current passing through the sample was a linear function of the d.c. bias voltage due to free moving charges. Second, at the same field strengths, the trapped carrier was thermally activated with activation energies of 13.6 meV for temperature range of 100−250100−250 K and 88.7 meV for 250−450250−450 K. In this conducting phase, the carrier transport was governed by space charge limited conduction mechanism. Third, when the electric field increased from 30 to 120 Vcm−1Vcm−1 , the ii became a quartic function of the vv because the carrier mobility is a quadratic function of the field strength. A conducting phase with high resistance was observed at temperatures below 100 K. The trapped carrier was thermally activated with activation energies of 146.5 meV for temperature range of 100−250100−250  K and 288.5 meV for 250−450250−450  K. Finally, in the electric field strengths of 120−2000120−2000 Vcm−1Vcm−1 , a high resistance phase appeared in the anionic solid at temperatures below 100 K. The current was a quadratic function of the d.c. bias voltage, and the carrier mobility was independent of the field strength

振動リード法によるBi2Sr2Ca2Cu3Ox超電導テープの内部摩擦測定

The 33rd Symposium on UltraSonic Electronics (USE2012): 第33回超音波エレクトロニクスの基礎と応用に関するシンポジウム, 2012年11月13日～15日, 千葉大学, 千

振動リード法を用いたリチウムイオン電池正極内部摩擦の評価

The 34th Symposium on UltraSonic Electronics (USE2013): 第34回超音波エレクトロニクスの基礎と応用に関するシンポジウム, 2013年11月20日～22日, 同志社大学, 京