WANG Dian， XIE Guangyuan，LYU Juntao，LI Wanwan
School of Materials and Metallurgy， Wuhan University of Science and Technology， Wuhan 430081， China
Abstract
Objective Negative temperature coefficient （NTC） thermistors are widely used in fields such as automotive electronics， household appliances， aerospace， and medical equipment due to their ability to measure temperature， provide temperature compensation， and suppress inrush current. To enhance the resistivity （ρ） and reduce the thermal sensitivity constant （B） of ceramic NTCs， this study investigates the effect of the co-precipitation method on the characteristic values of the yYCrxMn1-xO3-（1-y）Y2O3 system by adjusting the x and y ratios.
Methods Initially，during the preparation stage of the solid-phase method， eight different ratios of x and y were precisely selected to prepare rare-earth perovskite negative temperature coefficient thermistor （NTC） samples according to the yYCrxMn1-x O3-（1-y）Y2O3 system. The raw materials Y2O3， Cr2O3， and MnCO3 were accurately weighed according to each ratio. After steps such as grinding and mixing， they were pressed into shape and then sintered in a high-temperature furnace under specific temperature and time conditions. Subsequently， the crystal structure and phase composition of the samples were analyzed using X ray diffraction （XRD） technology. Meanwhile， electrical performance analysis was carried out to comprehensively evaluate parameters such as the direct current resistivity， thermistor constant B25/85， and activation energy Ea of the samples. After careful comparison， the optimal ratio （x=0.3， y=0.6） was finally selected. On this basis， the chemical co-precipitation method was adopted. YCl3·6H2O， CrCl3·6H2O， and MnCl2·4H2O were calculated， weighed， and batched according to a total mass of 100 g. They were dissolved in 5 mL of deionized water and continuously stirred. In a reverse addition manner， the solution was added to ammonia water and continuously stirred， keeping the pH of the solution at around 10. After stirring for 2 h， the solution was allowed to stand for precipitation. The supernatant was poured off， and the precipitate was washed with deionized water until neutral and then rinsed with absolute ethanol. After drying， it was presintered at 800 ℃ for 2 h. According to the masses of YCr0.3 Mn0.7O3 and Y2O3 corresponding to different y values， they were weighed， ground evenly， pressed into small round pieces of specific specifications， and sintered at 1 250 ℃ for 4 h to obtain negative temperature coefficient thermistor ceramics. Through the study of the properties of these ceramics， the influence of the co-precipitation method on the product performance was deeply explored.
Results and Discussion In the yYCr0.3Mn0.7O3-（1-y）Y2O3 system prepared by the co-precipitation method， when y≥0.6， the thermal sensitivity constant B25/85 was ≥2180 K， and the activation energy Ea was ≥0.19 eV. Conclusion By increasing the mass fraction of Mn4+ and decreasing the mass fraction of Y2O3， the yYCr0.3Mn0.7O3-（1-y）Y2O3 phase content can be increased， thereby reducing the material’s resistivity. This leads to improved sensitivity of the resistive value to temperature changes， reflected by an increase in the thermal sensitivity constant （B value）.
Keywords： chemical co-precipitation method； thermal constant； solid-phase method； thermistor ceramics； perovskite
Get Citation:WANG Dian， XIE Guangyuan， LV Juntao， et al. Effect of co-precipitation method on characteristic values of yYCrxMn1-xO3-（1-y） Y2O3 system［J］. China Powder Science and Technology， 2025， 31（2）： 105-111.
Received:2023-12-07.Revised:2024-05-13,Online:2025-02-25.
Funding Project:国家自然科学基金项目，编号：51904213。
First Author:王典（1999—），女，硕士生，研究方向为热敏陶瓷传感器的工艺设计。E-mail：2876136728@qq. com。
Corresponding Author:谢光远（1965—），男，教授，博士，硕士生导师，研究方向为传感器的开发。E-mail：121521197@qq. com。
DOI：10.13732/j.issn.1008-5548.2025.02.009
CLC No: TB4；TP212 Type Code:A
Serial No:1008-5548（2025）02-0105-07
