PHONON INTERACTIONS IN CRYSTALS.
Quarterly progress rept. no. 12, 15 Feb-14 May 66,
IBM THOMAS J WATSON RESEARCH CENTER YORKTOWN HEIGHTS NY
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A microscopic free energy function for antiferroelectrics has been derived as a power series in the complete group G of atomic displacements compatible with the translation group of the antiferroelectric phase. The atomic displacements in the antiferroelectric phase corresponding to extrema of the free energy form subgroups of G and give rise to a net polarization. The attenuation of phonons, both microwave ultrasonic and thermal, in lightly doped n-Ge and n-Si is interpreted in terms of a relaxation process of electrons bound to donors. Heat pulses have been observed in single crystal gallium in the temperature range 1.8-4 K. The temperature dependence of the electron-phonon mean free path obtained from the data is approximately T to the -3.3 or - .3 power. The largest electron transport velocity we measured was approximately 4 times 10 to the 7th power cmsec and is an order of magnitude faster than velocities observed in other metal crystals reported earlier. Author
- Electricity and Magnetism