Platinum, platinum-iridium (20 wt.%) and platinum-rhodium (10 wt.%) alloys were prepared as microwires using different methods. Microwires of Pt and its alloys with several diameters were prepared by passing wires of 1 mm of diameter through a drawplate. Afterwards, the Pt microwire was weared electrochemically in a fused salt mixture (NaNO3/NaCl: 4:1; 320°C) applying a square potential wave (1-50 Hz; 2.5 V). Microwires of Pt-Ir and Pt-Rh alloys were prepared applying a sine-shaped AC potential wave (60 Hz, 3-8 V rms), in 6 M NaCN + 2 M NaOH aqueous solution. The characterization of the interface metal-insulating material and the determination of geometric and effective radii of microelectrodes were carried out by means of optical and scanning electron microscopy, cyclic voltammetry and cronoamperometry. The Cd - v plot, where Cd is the apparent capacitance corrected by the electrode area and v the scan potential sweep was used to verify the interface metal-glass sealing conditions.
Microelectrodes preparation and sealing; platinum; platinum alloys
