Macroscopic and microscopic deformation of the piezoelectric Li_1tn2SO_1tn4_1tn.H_1tn2O, Li_1tn2SeO_1tn4_1tn.H_1tn2O and BiB_1tn3O_1tn6 crystals under an external electric field [Elektronische Ressource] / vorgelegt von Oleg Schmidt

Macroscopic and microscopicdeformation of the piezoelectricLi SO H O, Li SeO H O and BiB O2 4 2 2 4 2 3 6crystals under an external electric eldDISSERTATIONzur Erlangung des Grades eines Doktorsder Naturwissenschaftenvorgelegt vonDipl.-Phys. Oleg Schmidtgeb. am 12.07.1981 in Toparski/Karaganda (SU)eingereicht beim Fachbereich Physikder Universitat SiegenSiegen 2010Gutachter: Prof. Dr. Ullrich PietschProf. Dr. Ladislav BohatyTag der mundlic hen Prufung: 24.09.2010iiContentsIntroduction 11 Elastic, piezoelectric and dielectric properties of crystals 31.1 Elasticity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.2 Electric polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.2.1 Pyroelectric and ferroelectric crystals . . . . . . . . . . . . . . . . . 61.3 Piezoelectricity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 X-ray di raction by crystals under an static external electric eld 92.1 X-ray di raction by unperturbed crystals . . . . . . . . . . . . . . . . . . . 92.2 Electron density distribution in . . . . . . . . . . . . . . . . . . . . 112.2.1 Multipole re nement of the electron density . . . . . . . . . . . . . 112.2.2 DFT calculations of the electron density . . . . . . . . . . . . . . . 122.2.3 Topological analysis of the electron density . . . . . . . . . . . . . . 132.3 External and internal strain of a crystal induced by an applied electric eld 142.3.