Berlin 2015 – wissenschaftliches Programm
MM 28.32: Poster
Dienstag, 17. März 2015, 18:30–20:30, Poster E
Strong correlation between acoustic and electromagnetic emissions during plastic deformation and destruction in solids — Dimitris Mastrogiannis1, Tatiana Antsygina2, •Konstantin Chishko2, Claire Mavromatou1, and Vassilios Hadjicontis1 — 1University of Athens, Panepistimiopolis, Zografos, TK 157 84, Athens, Greece — 2B. Verkin Institute for Low Temperature Physics and Engineering, 47 Lenin Ave., 61103 Kharkov, Ukraine
Simultaneous acoustic (AE) and electromagnetic (EME) emissions during uniaxial compression of LiF monocrystals and polycrystalline natural rocks are studied experimentally and interpreted theoretically. It is proved the strong correlation between AE and EME in solids of different types. It means that both AE and EME have the same physical background in evolution of crystal lattice defects (dislocations, vacancies, cracks) during plastic deformation and destruction, despite the different ways to form acoustic or electromagnetic response from the same deformation act. Generation of EME is due to macroscopic polarization currents generated by dynamic lattice defects. In ionic crystals the currents are produced through pinning-unpinning between charged vacancies and dislocation lines which can transport the vacancies on macroscopically long distances. Granites are piezoelectric composites where deformation is mainly due to microcracking acts. Electromagnetic signal in this case forms within two steps: first, a short pulse from free charge re-distribution at crack nucleation, and, second, an electromagnetic satellite of emitted acoustic wave. EME is prospective for practical applications in areas where the only AE was used before.