采用两步法制备了(1-x)NiCo_(0.2)Mn_(1.8)O_(4)-xBaBiO_(3)(x=0.1、0.2、0.3、0.4)系列负温度系数(Negative Temperature Coefficient,NTC)复相陶瓷材料。系统研究了BaBiO_(3)(BB)含量对NiCo_(0.2)Mn_(1.8)O_(4)(NCM)基复相陶瓷的相结...采用两步法制备了(1-x)NiCo_(0.2)Mn_(1.8)O_(4)-xBaBiO_(3)(x=0.1、0.2、0.3、0.4)系列负温度系数(Negative Temperature Coefficient,NTC)复相陶瓷材料。系统研究了BaBiO_(3)(BB)含量对NiCo_(0.2)Mn_(1.8)O_(4)(NCM)基复相陶瓷的相结构、显微结构及电学性能的影响。结果表明,当x=0.1时,复相陶瓷内部均为细小均匀的三棱锥结构的尖晶石NiCo_(0.2)Mn_(1.8)O_(4)相。当x=0.2时,钙钛矿BaBiO_(3)相开始增多,且尖晶石晶粒开始长大、棱边开始变得圆润。当x达到0.3及以上时,内部晶粒继续长大,而且晶界明显增宽和变得模糊,呈现液相烧结特征,此外有第二相BaMnO_(3)开始生成并增多。阻抗分析表明,复相陶瓷的电阻主要决定于内部的晶界电阻。电阻分析表明室温电阻率ρ_(25℃)、温度敏感常数B、电导活化能E_(a)均呈现出随着BaBiO_(3)含量先降低后升高的趋势,且极小值出现在x=0.2时。该体系复合陶瓷的B值、ρ_(25℃)和E_(a)分别在4151~4374 K、4930~26206Ω·cm和0.357~0.376 eV的范围可调,拓宽了尖晶石体系热敏陶瓷的应用范围。展开更多
Nano-crystalline Ni1.0Co0.2Mn1.8O4 powders were synthesized via non-crystalloid precursor method. The results on the precursor by XRD and IR techniques show that the stable non-crystalloid precursor could be formed by...Nano-crystalline Ni1.0Co0.2Mn1.8O4 powders were synthesized via non-crystalloid precursor method. The results on the precursor by XRD and IR techniques show that the stable non-crystalloid precursor could be formed by adding oleic acide and adjusting the pH values. The dried precursor exhibited auto-catalytic combustion behavior. After being calcined at 800 ℃, the Ni1.0Co0.2Mn1.8O4 powders with spinel structure were obtained. It has been demonstrated that the synthesized powder is well dispersed and with higher sintering activity. The Model of non-crystalloid precursor has been suggested. The reaction mechanism has also been proposed.展开更多
文摘采用两步法制备了(1-x)NiCo_(0.2)Mn_(1.8)O_(4)-xBaBiO_(3)(x=0.1、0.2、0.3、0.4)系列负温度系数(Negative Temperature Coefficient,NTC)复相陶瓷材料。系统研究了BaBiO_(3)(BB)含量对NiCo_(0.2)Mn_(1.8)O_(4)(NCM)基复相陶瓷的相结构、显微结构及电学性能的影响。结果表明,当x=0.1时,复相陶瓷内部均为细小均匀的三棱锥结构的尖晶石NiCo_(0.2)Mn_(1.8)O_(4)相。当x=0.2时,钙钛矿BaBiO_(3)相开始增多,且尖晶石晶粒开始长大、棱边开始变得圆润。当x达到0.3及以上时,内部晶粒继续长大,而且晶界明显增宽和变得模糊,呈现液相烧结特征,此外有第二相BaMnO_(3)开始生成并增多。阻抗分析表明,复相陶瓷的电阻主要决定于内部的晶界电阻。电阻分析表明室温电阻率ρ_(25℃)、温度敏感常数B、电导活化能E_(a)均呈现出随着BaBiO_(3)含量先降低后升高的趋势,且极小值出现在x=0.2时。该体系复合陶瓷的B值、ρ_(25℃)和E_(a)分别在4151~4374 K、4930~26206Ω·cm和0.357~0.376 eV的范围可调,拓宽了尖晶石体系热敏陶瓷的应用范围。
文摘Nano-crystalline Ni1.0Co0.2Mn1.8O4 powders were synthesized via non-crystalloid precursor method. The results on the precursor by XRD and IR techniques show that the stable non-crystalloid precursor could be formed by adding oleic acide and adjusting the pH values. The dried precursor exhibited auto-catalytic combustion behavior. After being calcined at 800 ℃, the Ni1.0Co0.2Mn1.8O4 powders with spinel structure were obtained. It has been demonstrated that the synthesized powder is well dispersed and with higher sintering activity. The Model of non-crystalloid precursor has been suggested. The reaction mechanism has also been proposed.
