Evaluation of a Ni-Zn ferrite for use in temperature sensors

Abstract

This work investigates the variation of the real part of the complex magnetic permeability of a Ni-Zn ferrite for application to temperature sensors. Ferrite samples were fabricated by means of the conventional ceramic method. Zinc, nickel and iron oxides were used as raw materials. The samples were sintered at 1200, 1300, and 1400°C. The complex magnetic permeability of the samples was measured at temperatures ranging from - 40°C to +50°C. The complex magnetic permeability of the samples was analyzed in the 100 kHz-100 MHz frequency range, and the temperature sensitivity of the magnetic permeability (∂μ′r/∂T) was analyzed at 100 kHz. The magnetic permeability variation of the ferrite permits to use it as a temperature transducer with a maximum temperature sensitivity of about -119°C_1. The highest magnitudes of temperature sensitivity occurred between +30°C and +50°C. Therefore, the ferrite could be sensitive enough to allow temperature measurements at the human body temperature level. The results indicate that the temperature range of maximum temperature sensitivity of the ferrite may be adjusted by means of appropriate selection of the fabrication parameters.