| Summary: | 碩士 === 大同大學 === 材料工程學系(所) === 93 === In this study, the (Mn,Ni)3O4 spinel ceramics were investigated as NTC elements. The temperature depending properties, such as resistance and the coefficient of temperature were examined. The experiment were conducted to utilize coprecipitation to prepare the precursor powder by several combination of sintering process with various temperatures and atmospheres to study the variation following of physical properties.
The activation of Ni0.8Mn2.2O4 sintering at 1200℃ in nitrogen and argon is 3963.84 and 3945.436 respectively which is higher than those sintering in air (3853.357 ) and in oxygen (3740.487 ). When the samples were under the inert gas sintering, the electron jump activation and resistance were high. When the samples were under the oxygen atmosphere sintering, the resistance was decrease and electron jump activation was low. The ΔR/R of Ni0.8Mn2.2O4 increased with age time and the best resistivity stability is sintering at 1200℃ in air(ΔR/R =0.07% , 0.12% , 0.09%).
When Ni0.66Mn2.34O4 and Ni0.8Mn2.2O4 sintered in nitrogen and argon, the resistivity of the samples became higher with the segregation of NiO. The samples sintered in oxygen atmosphere could avoid the segregation of NiO and the single phase with spinel structure is obtained.
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