Newcas tle-upon-Tyne 1A study has been made of the anodic behaviour of lead and silver in N KOH with a view to determining the nature of the oxide layers formed and their influence upon measurements of oxygen overvoltage. Measurements of the variation of oxygen overvoltage with current density under constant surface conditions are reported for the two systems and the probable nature of the oxides deduced from voltage and, when possible, X-ray diffraction measurements. Comparison is made with earlier work.A recent study1 of the behaviour of lead in sulphuric acid during anodic polarization under conditions of constant apparent current density, has shown that the electrode reaction may be regarded as occurring in three stages.(i) A stage in which a lead sulphate layer is formed on the electrode surface, and which occurs at potentials near to the reversible PbjPbS04 potential. This layer eventually becomes complete, at least in the sense that the formation of lead sulphate cannot continue, and the electrode potential rises very rapidly to a sharp peak. The quantity of lead sulphate formed in this stage increases markedly with decreasing current density.(ii) The electrode potential falls rapidly from the peak, passes successively through a minimum and a maximum, and is at all times positive with respect to the reversible Pb02/PbS04/H2S04 potential. This stage is a complex one in which the formation of lead dioxide from the lead sulphate and the evolution of oxygen both contribute to the total electrode reaction, to extents which are dependent both on current density and time.

A method of determining overvoltage is described in which the current density can be rapidly altered from one value to another thus enabling the determination of the overvoltage against current density relationship to be examined under constant surface conditions. The method is applied to the determination of oxygen overvoltage on lead dioxide electrodes and the results, which show the marked superiority of this method over that usually employed, conform to the Tafel equation 7) = (2.303 RT/aF) loglo i + 0, with a value of a = 0.5.

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Recently the remarkable discovery of field-induced phase transition from antiferroelectric (AFE) to Ferroelectric (FE) in ferroelectrics excited the scientific community in this field. This finding has both scientific and technological implications to us. In this paper, we studied the changes of the crystal structure when an electrical field is applied to it. The X-ray diffraction pattern reflecting these changes was discussed by theoretical calculation.