2.2. Ceramics characterization
Next, the pellets were removed from the platinum foils, embedded in an epoxy resin under vacuum and progressively polished down to 0.1 μm diamond paste and etched with acetic acid with a concentration of 0.5% for 2 s. Then, they were gently cleaned in an ultrasonic bath with distilled water, dried and palladium coated for scanning electron microscope (SEM-Hitachi S-3500N, Ibaraki, Japan) observations. The chemical composition of crystalline grains was qualitatively determined with an energy dispersive spectroscopy (EDS-INCA-Oxford) system coupled to the above-described electron microscope.