Synthesis and high thermal stability of Mn doped Y2/3Cu3Ti4O12 negative temperature coefficient ceramic

Highlights: • In this paper, high thermal stability of Mn doped Y_2/3Cu₃Ti₄O₁₂ negative temperature coefficient (NTC) ceramics have been successfully fabricated by the combination of Pechini powder synthesis and solid-state reaction sintering • The structure of as-sintered ceramics is a single Y_2/3Cu₃Ti₄O₁₂ phase at x≤0.5, while the CuO phase begins to appear at x≥0.7. • The change of resistivity is related to the change of microstructure and the increase of Cu⁺/Cu²⁺, Ti³⁺/Ti⁴⁺, Mn⁴⁺/Mn³⁺. • After annealing at 125°C in air for 800h, the aging coefficient (ΔR/R) of these materials is less than 0.4%, showing excellent stability. In this paper, high thermal stability of Mn doped Y_2/3Cu₃Ti₄O₁₂ negative temperature coefficient (NTC) ceramics have been successfully fabricated by the combination of Pechini powder synthesis and solid-state reaction sintering. The substitution of Mn for Ti plays a critical role in controlling the phase structure, microstructure, electrical properties, and stability. The structure of as-sintered ceramics is a single Y_2/3Cu₃Ti₄O₁₂ phase at x≤0.5, while the CuO phase begins to appear at x≥0.7. X-ray photoelectron spectroscopy further confirms the change of cation concentration, one of the critical factors for electrical conductivity in Y_2/3Cu₃Ti_4-xMn_xO₁₂ ceramics. In the temperature of −50–250°C, the resistivity all decreases with increasing temperature and Mn content, the aging coefficient of all samples is within 0.4%, and the minimum can reach 0.2%. We strongly propose that the Mn substitution and Pechini method are highly desirable for the fabrication of high stability NTC thermistors for medi-temperature region application.