Simplified vibrating-reed technique for the measurement of the temperature dependence of Young’s modulus of small samples

Abstract

A simplified vibrating-reed technique for the measurement of the temperature dependence of Young’s modulus of small thin samples is described. The vibration of the reed is detected optically rather than with a capacitively coupled electrode as has been used by previous investigators. The optical coupling greatly simplifies the sample stage and electronic circuitry. It is made possible by the use of a microminiature Joule–Thomson-effect refrigerator which mounts directly onto the X–Y stage of a metallurgical microscope. Because of the refrigerator’s small size and lack of mechanical vibrations, the high-quality room temperature optics of the microscope can be used to detect the small amplitude vibration of the reed over a wide temperature range. We observe the Curie and Neel points of the magnetic phase transitions of terbium at Tc =221 K and TN =233 K, respectively. In addition, we measure Young’s modulus at 280 K to be 5.90×1011 dyn/cm2.