H. Wada

Bio: H. Wada is an academic researcher. The author has contributed to research in topics: Ionic conductivity & Orthorhombic crystal system. The author has an hindex of 1, co-authored 2 publications receiving 19 citations.

Crystal Structures and Ionic Conductivities of New Silver Hafnium Sulfides.

Abstract: The phase relations of the AgHfS system were examined at elevated temperatures (600–1000 °C). The new compounds Ag 2 HfS 3 and Ag 4 Hf 3 S 8 were found. Phase transformation of Ag 2 HfS 3 was observed to occur at around 700 °C. The low-temperature Ag 2 HfS 3 was obtained as single crystals from a stoichiometric mixture of Ag 2 S and HfS 2 at 650 °C in evacuated silica tubes. It crystallizes in space group Cmca (No. 64) of the orthorhombic system with eight formula units of cell dimensions a = 11.458(2) A , b = 6.628(1) A , c = 12.774(2) A , V = 970.0(2) A 3 . The structure of Ag 2 HfS 3 was determined using single-crystal X-ray diffraction with a CAD4 four-circle diffractometer, refined to a reliability factor R = 4.1% from 700 independent reflections and 32 variables. Hf and Ag atoms are coordinated by six and four S atoms to form HfS 6 octahedra and AgS 4 tetrahedra respectively. The structural feature of Ag 2 HfS 3 is the alternative packing of layers of HfS 6 octahedra and AgS 4 tetrahedra along the c direction. This compound exhibits silver ionic conductivity logσ Ag + = −3.0 at 22 °C.

An Organic Mixed Ion-Electron Conductor for Power Electronics.

Abstract: A mixed ionic–electronic conductor based on nanofibrillated cellulose composited with poly(3,4-ethylene-dioxythio­phene):­poly(styrene-sulfonate) along with high boiling point solvents is demonstra ...

AC and DC conductivity around the ferroelectric phase transition in (CH3NH3)3Bi2Br9 (MABB) crystal

Abstract: The temperature dependence of dc and ac conductivity in the vicinity of Tc3 = 112.5 K (on heating) for the MABB crystal was measured. For ac conductivity the frequencies between 20 Hz and 1 MHz were applied. The behaviour of conductivity was explained by means of power law [sgrave]ac = [sgrave]dc + Aωp, where ω is the frequency and p ≪ 1. The activation energies both for dc and ac conductivity were estimated.

Transport properties and polarization phenomena in intercalated Ag x HfSe 2 compounds

Abstract: The electrical properties of intercalated Ag x HfSe2 compounds (x = 0.1, 0.2) have been investigated for the first time. Investigations have been performed using various current electrodes, which make it possible to pass either the electron current or the ion current across the sample. Polarization effects, which indicate the self-consistent migration of charge carriers in the samples, have been found for the samples at room temperature. Based on the characteristic features of polarization decay, coefficients of conjugated chemical diffusion have been evaluated.

Specific features of the charge and mass transfer in a silver-intercalated hafnium diselenide

Abstract: The specific features of the charge transfer in intercalated samples of AgxHfSe2 have been studied for the first time by alternating current (ac) impedance spectroscopy. It has been found that relaxation pro� cesses in an ac field are accelerated with increasing silver content in the samples. The complex conductivity (Y) shows a frequency dispersion described by power law Y ~ ω s , which is characteristic of the hopping con� ductivity mechanism. The Agx HfSe 2 compounds demonstrate shorter relaxation times as compared to those observed in hafnium diselenide intercalated with copper atoms, and this fact indicates that the charge carrier mobility in the silverintercalated compounds is hi gher. The possibility of silver ion transfer in AgxHfSe2 is confirmed by the measurements performed by the method of electrochemical cell emf.