Thick-film NTC thermistors based on spinel-type semiconducting electroceramics

Thick-film NTC thermistors based on spinel-type semiconducting electroceramics of different composition /Cu_0.1Ni_0.1Co_1.6Mn_1.2O₄ (No.1), Cu_0.1Ni_0.8Co_0.21Mn_1.9O₄ (No.2), and Cu_0.8Ni_0.1Co_0.2Mn_1.9O₄ (No.3)/ were fabricated. Basic bulk ceramics and fired thick films were characterized by XRD, SEM and EDX microanalysis. Thick films of No. 1-2 ceramics showed higher density and microstructure homogeneity over those of No.3 ceramics. The electrical parameters of planar thick-film and disc-type NTC thermistors were determined and compared. Depending on chemical composition of ceramics, the prepared thick-film elements showed the resistivities in the range of 2 ÷ 40 Ω·m, being approx. the 1-2 orders of magnitude larger over those of disc thermistors. The values of constant B₂₅85/ ranged from 2980 to 3690 K. Taking into account good reproducibility and satisfactory sensitivities (the values of TRC α≤-4 %/K) of Cu_0.1Ni_0.1Co_1.6Mn_1.2O₄- and Cu_0.1Ni_0.8Co_0.2Mn_1.9O₄-based thickfilm NTC thermistors, they should be suitable as accurate temperature sensors.