摘要
为制备材料常数(B值)1900K左右宽温区NTC热敏电阻,将Pechini方法制备的Mn0.43Ni0.9CuFe0.67O4粉体置于2.45GHz多模腔微波炉中,经不同温度下微波煅烧压制成型后,于1000℃下微波烧结.采用红外(FT-IR),X射线衍射(XRD),扫描电镜(SEM),粒度分析分别对样品的晶体结构、相组成、形貌和粒度分布进行了表征.结果表明,不同煅烧和烧结工艺对元件的电学性能有很大的影响;微波最佳煅烧温度为650℃,比常规煅烧所需温度低;微波烧结能够获得微观结构均匀致密的陶瓷体;微波烧结制得元件的B值和电阻率均匀性较好,其B值平均值为1930K,偏差为0.31%,电阻率ρ的平均值为135Ω.cm,偏差为4.55%;而常规烧结制得元件的B值平均值为1720K,偏差为1.47%,电阻率ρ的平均值为78Ω.cm,偏差为25.34%.复阻抗分析表明,微波烧结后样品的晶粒电阻Rb和晶界电阻Rgb分别为255和305Ω,而常规烧结样品的晶粒和晶界电阻分别为200和230Ω.
In order to obtain the NTC thermistors with small B constant （about 1900K）, applied to wide temperature range, Mn0.43Ni0.9CuFe0.67O4 NTC thermistor materials prepared by Pechini method were microwave-calcined at different temperatures （650℃, 750℃ and 850℃）. The calcined Mn0.43Ni0.9CuFe0.67O4 powders were pressed and then sintered at 1000℃ in a microwave furnace （multimode cavity, 2.45GHz）.The crystal structure, phase compositions, morphology and particle size distribution of the samples were analyzed by FT-IR, X-ray diffraction （XRD）, scanning electron microscope （SEM） and a laser particle size analyzer. The experimental results show that the electrical properties of the ceramics are strongly dependent on the calcination and sintering process. The application of microwave leads to a lower calcination temperature （650℃） and densified uniform microstructures. Microwave sintering can obtain the components with well uniformity of B constant and resistivity, of which the Bavg. is 1930K （deviation of 0.31%） and resistivity ρavg. is 135Ω·cm （deviation of 4.55%）. However, the Bavg. is 1720K （deviation of 1.47%） and resistivity ρavg. is 78Ω·cm （deviation of 25.34%） for the conventionally sintered components. From complex impedance analysis, the grain resistance （Rb） and grain boundary resistance （Rgb） are respectively 255Ω and 305Ω for the microwavesintered samples. The Rb and Rgb are respectively 200Ω and 230Ω for conventionally sintered samples.
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第5期1013-1018,共6页
Journal of Inorganic Materials
基金
乌鲁木齐市科技攻关项目(G06211002)
乌鲁木齐市种子基金(K08141001)
