O. Yamamoto

Electrical conductivity of some hydroxyapatites

Abstract The electrical conductivity of hydroxyapatite, M 10 (PO 4 ) 6 (OH) 2 (M = Ca, Sr, Ba, Cd, Pb….), has been measured in the temperature range from 200°C to 800°C. The nature of charge carriers in Ca 10 (PO 4 ) 6 (OH) 2 and Pb 10 (PO 4 ) 6 (OH) 2 is examined by the emf measurement and the electrolysis experiment. These results suggested that the OH − ion is the charge carrier in calcium-hydroxyapatite, and the OH − ion and the electron in lead—hydroxyapatite.

Ionic conductivity and coulometric titration of copper selenide

Abstract The ionic conductivity of copper selenide was measured in the temperature range of 30–180°C by blocking the electronic current by the copper ion high conductivity solid electrolyte, 37CuBr·3[C 6 H 12 N 2 ·2CH 3 Br]. It was found that the α-phase of Cu 2−δ Se has a high ionic conductivity; for example, Cu 1.75 Se exhibited an ionic conductivity of 3 × 10 −2 ohm −1 cm −1 at room temperature. The coulometric titration of copper selenide was carried out with the help of the cell, Au/Cu 2−δ Se/solid electrolyte/Cu; from the temperature dependence of the cell voltage, the β-α transition temperatures of Cu 2−δ Se were determined as a function of δ.

Proton conduction in triethylenediamine- and hexamethylenetetramine-sulfate

The electrical conductivities of the triethylenediamine- and hexamethylenetetramine-sulfuric acid systems have been measured and comparatively high electrical conductivities were found in the solid state. The protonic nature of charge carriers was confirmed by an electrolysis experiment and an EMF measurement. In the electrolysis experiment the evolution of hydrogen gas was found to be directly proportional to the electrical charge passed across the crystal and in the EMF measurement the cell potential followed the Nernst equation.

Solid state ionics. High ionic conductivity solid in silver halide-silver sulphate system

The ionic conductivities and phase diagrams of AgI-Ag2SO4, AgCl-Ag2SO4 and AgBr-Ag2SO4 systems have been studied with the help of electrical conductivity, transport number, DTA and X-ray studies. In the AgI-Ag2SO4 system, the solid solution of α-AgI with Ag2SO4 was quenched to room temperature to have high ionic conductivity of 5·0×10−2 (ohm. cm)−1 at room temperature and 1·3×10−3 (ohm. cm)−1 at −78°C. The quenched solid solution was stable at −20°C, but gradually decomposed toβ-AgI andβ-Ag2SO4 at room temperature. The transport number of silver ion in this solid solution was about 1·0. In the AgCl-Ag2SO4 and AgBr-Ag2SO4 systems, the electrical conductivity was of the order of 10−4 to 10−6 (ohm. cm)−1 at room temperature.

Solid-state ionics-solid electrolyte cells with copper ion conductors

A solid electrolyte cell has been developed using a high copper ion conductivity solid electrolyte, 7CuBr·C6H12N4CH3Br, a copper anode, and a chalcogen cathode. The open-circuit voltages of the cells with sulphur, selenium, and tellurium as cathode materials were 0·448, 0·373, and 0·258 V, respectively, at 25° C. These cells yielded a current of several tens of microamperes at room temperature and several milliamperes at 114° C without appreciable polarization. An energy density of 4.5 Wh kg−1 at room temperature was evaluated from the weights of the electrolyte and electrode materials for the cell using a selenium cathode in the discharge current density range 60–150μA cm−2.

An electrochromic cell using a solid proton conductor

An electrochromic cell with a solid proton conductor, HUO2PO4 · 4H2O, as the electrolyte is described and its performance was investigated.

Phase diagrams of the coper(I) bromide-lead bromide and copper (I) iodide-lead iodide systems and the ionic conductivity of CuPb3Br7

Abstract The phase diagrams of the systems CuBrue5f8PbBr 2 and Cuiue5f8PbI 2 have been determined by the use of differential thermal analysis and X-ray diffraction analysis. A new compound CuPb 3 Br 7 has been found in the CuBrue5f8PbBr 2 system. This compound is stable between its incongruent melting point (300°C) and 160°C, and below 160°C disproportionates to CuBr and PbBr 2 . It has a relatively high ionic conductivity of 3 × 10 −2 (ohm-cm) −1 at 200°C and a low activation energy for conduction of 22 kJ/mole. The transport number measurement with Tubandts method shows that the copper ions must be considered as the only charge carriers. No intermediate compound has been found in the CuIue5f8PbI 2 system.

Proton conduction in some solids and the fuel cell with a proton conducting electrolyte

Abstract The electrical conductivities of some organic and inorganic solids, such as the simple organic acids, NH4H2PO4, KH2PO4, H3BO3, λ-AIOOH, amine-sulfates and amine-phosphates, have been measured. A relatively high proton conductivity of about 1 × 10−3 ohm−1 cm−1 at 87°C was found in hexamethylenetetramine phosphate. The performance of a hydrogen-air fuel cell with proton conducting solid electrolytes has been measured at 174 C. The open-circuit voltage of the cell was 960 mV and the short-circuit current was 6 mA/cm2.

High-conductivity solid copper ion conductors: the sulphonium halide-copper(I) halide systems

The electrical conductivities of the copper (I) halide-sulphonium halide systems were measured and high conductivity copper ion conductors were found in the copper (I) iodide-1-methyl-1-thioniacyclohexane iodide (C5H10SCH3I) and copper (I) iodide-4-methyl-1, 4-oxathianium iodide (C4H8OSCH3I) systems. The dependence of electrical conductivity on the composition showed that the maximum conductivity appeared at 83.4 mol% CuI for these two systems. The highest conductivities of the systems, CuI-C5H10SCH3I and CuI-C4H8OSCH3I, were 1.4×10−3 and 7.2×10−4 (Ω cm)−1 at 25‡ C, respectively. The conduction in these systems was essentially ionic.

Solid state ionics—The ionic conductivity of the Ag2S-Ag1.70Te-AgX system (AgX; Ag4P2O7, Ag3PO4 and AgPO3)

The thermal reaction products in the Ag2S-Ag1.70 Te-Ag4P2O7, Ag2S-Ag1.70 Te-Ag3PO4 and Ag2S-Ag1.70 Te-AgPO3 systems were found to exhibit both high ionic and electronic conductivity at room temperature. For example, the ionic conductivities of (Ag2S)0.69 (Ag1.70Te)0.285 (Ag4P2O7)0.025, (Ag2S)0.5(Ag1.70Te)0.45 (Ag3PO4)0.05 and (Ag2S)0.65 (Ag1.70Te)0.25(AgPO3)0.1 were 0.25, 0.25 and 0.22 (ohm. cm)−1 at 25°C, respectively. Differential thermal analysis and X-ray diffraction showed that these high ionic conductivity solids had an α-Ag2S-like structure at room temperature.