林 英子

Prussian blue (PB), which is a mixed-valent polynuclear metal complex, was formed in the presence of the solid polymer electrolyte membrane Nafion (Nf). According to the stepwise dipping method, in which either Fe or Fe(CN)6 of the component ions of PB was first incorporated into the matrix membrane and then the membrane was immersed into a solution containing the other component ion, a thin layer of PB was deposited on the surface of Nf or inside Nf depending upon the sequence of incorporation of the component ions. A dissipative structure of periodic PB layer deposit inside Nf was found to be formed under a specific condition of the stepwise method. PB was also formed inside Nf as a broader line by the countercurrent diffusion method in which both component ions were incorporated into Nf from opposite surfaces. The position of PB in Nf varied with the concentration ratio of Fe to Fe(CN)6 in this case. © 1989, Taylor & Francis Group, LLC. All rights reserved. 2+ 3- 2+ 3-

Homogeneous precipitation method using urea was applied to the preparation of calcium phosphates. Acidic-aqueous solutions (0.5 mol&middot;dm^-3 HNO₃ 500cm³) containing 0.167 mol&middot;dm^-3 Ca (NO₃) ₂, 0.1 mol&middot;dm^-3 (NH₄) ₂HPO₄ (Ca/P=1.67) and 0.5 mol&middot;dm^-3 (NH₂) ₂CO were refluxed respectively at 80, 90, 95 and 100 &deg;C for various lengths of time. The pH of each solution was measured continuously during the reaction. The products were characterized by X-ray powder diffractometry, IR spectroscopy, SEM and TG. During the reaction, two morphologies of the products were formed and separated into two layers at the initial stage; agglomerates of particles of dicalcium phosphate anhydrate (CaHPO₄) at the bottom of the flask and fibrous octacalcium phosphate [Ca₈H₂ (PO₄) ₆&middot;5H₂O, OCP] in the upper solution. After the reaction finished, both products changed completely into apatite containing CO₃^2- (CO₃Ap).<BR>The other results were as follows : <BR>(1) A mixture of whisker-like CO₃Ap and fibrous CO₃Ap was obtained under the reaction conditions of 100&deg;C-17h and 95&deg;C-47h and 90&deg;C-80h, the fibrous OCP was also obtained at 80&deg;C-22h. The CO₃Ap was formed with the hydrolysis of CaHPO₄ and OCP, which both precipitated at the initial stage.<BR>(2) By heating up to 1200&deg;C in air, the CO₃Ap obtained at 95&deg;C-47h and 90&deg;C-80h changed into hydroxyapatite [Ca₁₀ (PO₄) ₆ (OH) ₂, HAp], losing CO₂. The CO₃Ap obtained at 100&deg;C-17h changed into the mixture of HAp and &alpha;-tricalcium phosphate [&alpha;-Ca₃ (PO₄) ₂, &alpha;-TCP] by heating. Even after the heating, the HAp had whisker-like or fibrous morphology. However, the OCP fiber shrank and showed partially sinterability due to the heating.<BR>(3) The flexible sheets and porous compacts of CO₃Ap and OCP were obtained.

On the complex formation of Prussian Blue (PB) in a solid matrix of Nafion membrane (Nf), it was possible to control a structure of the PB&ndash;Nf composite membrane by regulating the rate and direction of diffusion in the solid phase of two component ions, Fe²⁺ and Fe(CN)₆^3&minus;.

A solid-state thin film rechargeable battery has been prepared using a novel efficient technique of “surface complexation method” by which a thin layer of Prussian blue (PB) can be overlaid on a solid polymer electrolyte of Nafion (Nf) as matrix. An electrochemical cell made of the composite PB-Nf film sandwiched with supporting electrodes was examined on i-V curves in solid state and for characteristics as a rechargeable battery. The resulting PB-Nf battery showed good durability in repetitive cycles of charging and discharging and gave the following results: open-circuit voltage of the unit cell per 160 μm 0.68V, short-circuit current 0.2-2 mA/cm depending upon the water content of the Nf matrix, and an energy density of about 50 Wh/kg. © 1987, The Electrochemical Society, Inc. All rights reserved. 2

Much attention has been directed during the past decade to the so-called 'plastic battery' as a lightweight and high energy density rechargeable battery. We have found an efficient method for construction of thin film solid state devices in which a polymer metal complex (PMC) and a solid polymer electrolyte (SPE) are combined to form a multilayered thin film. The resulting composite film consisting of PMC and SPE has been found to be potentially useful as an electroactive material for a thin film solid state rechargeable battery.

The polynuclear transition metal complex, Turnbull's blue, can be formed in solid polymer electrolyte to make a thin-film solid-state electrochemical cell.