Beschreibung:
The relationship between Mn-Co-Ni-O ceramic slurry formulations and their volatility, rheology and stability, as well as the electrical properties of free-standing ultrathin sheets made from slurries were systematically investigated. The ceramic slurry with high solid content of 60%, viscosity lower than 12000 mPa·s and 720 h long-term stability was successful obtained by designing the spherical clusters powder and organic carrier. The spherical clusters powders were formed by secondary aggregation and reinforced the wettability on the surface of the powder. Such spherical clusters ensure that the powders created for ceramic slurry are compact and have good fluidity features microscopically. The optimal formula of the organic carrier system contains three components by 90 wt% organic solvent, 5 wt% ethyl cellulose and 5 wt% Span 85, where the organic solvent was built by terpineol: butyldiglycol: 2-(2-butoxyethoxy) ethyl acetate = 70:10:20. The Mn-Co-Ni-O free-standing ultrathin sheets was prepared by screen printing method using this slurry, giving the resistivity of 317.1 Ω·cm at 25 °C, thermal constant of 3407 K, activation energy of 0.294 eV, and temperature coefficient of resistance of -3.83%/K , respectively. Such Mn-Co-Ni-O free-standing ultrathin sheets with excellent NTC characters are promising candidates for temperature measurements and uncooled infrared detectors applications