| 摘要 |
PURPOSE:To make it possible to the density of intrinsic point defect by a method wherein an external magnetic field is impressed on a crystal sample, an ultrasonic wave is passed through the sample while it is cooled, and a change in the acoustic velocity of the ultrasonic wave in the crystal sample or the relation between a change in absorption of the ultrasonic wave and a temperature of cooling the crystal sample is measured. CONSTITUTION:Cooling equipment having a sample measuring box 4 is so designed that it is inserted between superconducting magnets and that a magnetic field of 0 to 10 tesla, at least, can be impressed with continuous variation. Measurement of the relative acoustic velocity of an ultrasonic wave transmitted through a crystal sample 2 from a first piezo element ultrasonic transducer 31a to a second piezo element ultrasonic transducer 32a is executed by comparing a pulse signal generated by an ultrasonic pulse generating device 31 with the pulse signal detected by an ultrasonic wave detecting device 32. Based on the result of measurement of the acoustic velocity and the amount of fall of a V-T curve showing the relation between the acoustic velocity of the ultrasonic wave in the crystal and temperature, the density of intrinsic point defect is determined by proportional conversion. |
