Measurement Methods and Equipment

Measurement Method and Instrument

For the magnetic susceptibility measurement, two types of magnetic susceptibility meters were used, i.e. “Model 3101A”(Bison Instruments, U.S.A) and “Model MS 2”(Bartington Instruments, U.K).

For the natural remanent magnetization (NRM) measurement, a spinner magnetometer ”Model SMD- 88 (SMM-85)” (Natsuhara Gikken, Japan) was used．

To determine the Curie temperature, a type of “VSM-155“(Princeton Applied Research Corp., U.S.A) was used for the measurement of thermomagnetic curve in the magnetic field of 0.8 T under 10^-3 Pa in vacuum.

Dry density measurement was conducted after drying the specimen in the air at room temperature for several months. Wet density measurement using deionized water was made for the specimen left in the vacuum chamber with water after 40 hours.

Ultrasonic velocity (Vp) was measured using the combination of “pulse generator and syncroscope” with a 0.5 or 1 MHz transducer. Or an ultrasonic velocity measurement device, “Model NSPG-53D”(Kaihatsu Densisokki, Japan) under the room temperature and atmospheric pressure.