The processing and characterization of Pb(Mg_1/3Nb_2/3)O₃ (PMN) powders for coating capacitor

The present paper extensively demonstrates synthesis, characterization and electrical properties of relaxor ferroelectric Pb(Mg_1/3Nb_2/3)O₃ (PMN) sub-micron powders and PMN coatings on n-type Si substrates using sol-gel technique for capacitor applications. Transparent solutions were prepared from Pb, Mg and Nb based precursors, methanol and glacial acetic acid (GAA). The obtained solutions were dried at 80°C for 60 min in air to form gel structure of PMN mixture and heat treated at 530°C for 3 h and subsequently annealed at the temperature range of 800°C and 1000°C for 2 h in air. After the sintering, the PMN powders were milled for 24 h to obtain sub-micron powders. The powder size was measured using particle size machine. Finally, the powders were dispersed in alcohol and the obtained suspension was coated on n-type Si substrates. The films were dried at 50°C for 15 min and subsequently were heat treated at 730°C for 30 min in air to ensure its adhesion strength. Thermal, structural, microstructural, mechanical and electrical properties of the powder and the coatings were characterized by differential thermal analysis-thermo gravimeter (DTA/TG), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), refractometer, spectrophotometer and high resolution dielectric analyzer machines. The study provides a new insight on the sub-micron powders of PMN structure coated on Si semiconducting surface.