Ni鈥揗n鈥揊e鈥揅r鈥揙 negative temperature coefficient thermistor compositions: Correlation between processing conditions and electrical characteristics

详细信息

下载全文

推荐本文 |

• 作者：Justin M. Varghese ; A. Seema and K. R. Dayas
• 关键词：Nickel manganite ; NTC thermistors ; Sintering temperature ; Electrical properties
• 刊名：Journal of Electroceramics
• 出版时间：June, 2009
• 出版年：2009
• 期刊代码：68_13853449
• 类别：med
• 卷：22
• 期：4
• 页码：436-441
• 数据来源：sp

摘要

A study has been carried out to correlate the effect of sintering temperature on the microstructural, electrical and reliability aspects of Ni_0.75Mn_{(2.25−x−y)}Cr _x Fe _y O₄ (x = 0 to 0.3 and y = 0 to 0.3) negative temperature coefficient thermistor compositions prepared by solid-state route. The calcined and sintered compositions were characterized by X-ray diffraction and Scanning Electron Microscopy. The existence of cubic spinel single-phase region was determined by sintering Ni_0.75Mn_{(2.25−x−y)}Cr _x Fe _y O₄ samples in air at temperatures 1150 to 1250 掳C. X-ray diffraction patterns of samples sintered above 1200 掳C shows additional Bragg reflections of a rock salt structured NiO phase besides normal cubic spinel. A maximum B-value of 4044 K was obtained for Ni_0.75Mn_1.95Cr_0.25Fe_0.05O₄ composition at a sintering temperature 1250 掳C/3 h. The reliability of the thermistor compositions were evaluated by performing accelerated ageing based on thermal cycling test. We found that chromium enhances the reliability of Ni_0.75Mn_{(2.25−x−y)}Cr _x Fe _y O₄ (x = 0 to 0.3 and y = 0 to 0.3) based NTC thermistor compositions. A maximum reliability of +0.25%resistance drift was observed at sintering temperature 1200 掳C for 0.25 mol%chromium content. Excellent reliability of Ni_0.75Mn_{(2.25−x−y)}Cr _x Fe _y O₄ NTC thermistor compositions makes it ideal candidates for high-performance thermal sensor applications.