Le Duc Thang, Ju Heongkyu
Department of Physics, Gachon University, Seongnam 13120, Korea.
Materials (Basel). 2021 Mar 12;14(6):1389. doi: 10.3390/ma14061389.
Toward the development of NTCR thermistors, nanocrystalline Mn-Ni-Cu-O powder was synthesized from a mixed chloride aqueous solution by a simple co-precipitation method.The introduction of an oxidizing agent (HO) into the solution led to the partial oxidation of Mn ions into Mn ions, which enabled the collected powder to be well crystallized at 650 °C. Such a low calcining temperature resulted in fine particles with a mean size of 60 nm, which significantly promoted densification of the resulting ceramics. As a result, a dense and homogenous microstructure with a relative density up to 97.2% was achieved for pellets sintered at 1100 °C. Furthermore, these sintered ceramics exhibited a room temperature resistivity () of 67 Ω·cmand a thermistor constant () of 2843 K, which make them suitable for use in industrial thermistors. In addition, electrical stability was greatly improved when the ceramics were prepared by a new two-step sintering method. The results suggest that the co-precipitation route with the introduction of HO is suitable for the fabrication of cubic spinel thermistor nanopowders.
为了开发负温度系数热敏电阻（NTCR），通过简单的共沉淀法从混合氯化物水溶液中合成了纳米晶Mn-Ni-Cu-O粉末。向溶液中引入氧化剂（HO）导致Mn离子部分氧化为Mn离子，这使得收集到的粉末在650℃下能够很好地结晶。如此低的煅烧温度产生了平均尺寸为60nm的细颗粒，这显著促进了所得陶瓷的致密化。结果，对于在1100℃烧结的球团，获得了相对密度高达97.2%的致密且均匀的微观结构。此外，这些烧结陶瓷表现出室温电阻率（）为67Ω·cm，热敏电阻常数（）为2843K，这使得它们适用于工业热敏电阻。此外，当通过新的两步烧结法制备陶瓷时，电稳定性得到了极大的改善。结果表明，引入HO的共沉淀路线适用于制备立方尖晶石热敏电阻纳米粉末。
