Characteristics of a Type of NTC Thermistors for Cryogenic Applications

摘要

A new type of miniature negative temperature coefficient (NTC) thermistors has been developed and manufactured with Mn-Ni-Cu-Fe oxides. The prepared NTC thermistors were calibrated in the temperature range from 77 K to 300 K with 1 A exciting currents. The automatic calibration apparatus as well as thermometric characteristics, stability, calibration equations and interchangeability of the manufactured thermistors were investigated. A mean fit equation was obtained: 1/T = 8.60 10~(-4) + 6.54 10~(-4) ln(R/R_(ref)) + 2.46 10~(-5) ln(R/R_(ref))~2 + 9.48 10~(-7) ln(R/R_(ref))~3 - 2.16 10~(-8) ln(R/R_(ref))~4. All the prepared NTC thermistors agreed with this fit with an error of 1.5 K. If the greater accuracy is required, a calibration is necessary, and the calibration accuracy is estimated to be 10 mK.