LaMnO3–Ni0.75Mn2.25O4 Supported Bilayer NTC Thermistors

A bilayer concept was proposed to adjust the electrical properties of NTC thermistors. The conventional NTC material Ni 0.75 Mn 2.25 O 4 was chosen as the sensitive layer, and high conductive LaMnO 3 – Ni 0.75 Mn 2.25 O 4 composite was chosen as the support layer. The bilayer NTC thermistors were successfully fabricated by classical uniaxial pressing method. After cosintering at 1235°C for 4 h, the two layers adhered well to each other without any cracking or delamination. The resistance decreased linearly with the decrease in the thickness of Ni 0.75 Mn 2.25 O 4 layer, and the B values varied between 3868 and 3901 K. After annealing at 150°C in air for 500 h, the resistance shifts at 25°C were less than 1%, which mean that the bilayer NTC thermistors had high stability.