Abstract
Progress in microelectronic technology has allowed us to design and develop a simple but, professional quality instrument for ultrasonic pulse-echo probing of the elastic properties of materials. The heart of this interfer- ometer lies in the AD8302 microchip, a gain and phase detector from Analog Devices, Inc. The interferometer was tested by measuring the temperature dependences of the ultrasound speed and attenuation in a ferro- electric KTa0.92 Nb0.08 O3 (KTN) crystal at a frequency of about 40 MHz. These tests demonstrated that our
instrument is capable of detecting the relative changes in the sound speed v on the level of ∆v/v ∼ 10−7 .
Moreover, this low-cost instrument was able to reveal previously unresolved feature - e.g. the theoretically
expected velocity kink at the KTN phase transition to orthorhombic symmetry. Additionally, the ultrasound attenuation revealed new features in the development of the low-temperature structure of the ferroelectric KTN crystal.