Berlin 2018 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 17: Topical Session (Symposium MM): Fundamentals of Fracture
MM 17.4: Talk
Monday, March 12, 2018, 18:15–18:30, TC 006
Onset of damage and anisotropic fracture behaviour of LiTaO3 and LiNbO3 single crystals — •Manuel Gruber1, Raul Bermejo1, Peter Supancic1, Maxim Popov2, Alexander Leitner3, and Daniel Kiener3 — 1Institut fuer Struktur- und Funktionskeramik, Montanuniversitaet Leoben, Austria — 2Materials Center Leoben Forschung GmbH, Leoben, Austria — 3Department of Materials Physics, Montanuniversitaet Leoben, Austria
The requirements on new materials used in mobile communications are governed by the constantly growing data transfer rates. Single crystal piezoelectric materials, e.g. LiTaO3 and LiNbO3, have qualified as good candidates for accurate and efficient frequency filters and are thus also considered for the newest 5G mobile network standards. To optimize the functionality of the filters, a particular orientation and surface conditioning of the single crystal substrate must be ensured. This can affect the structural integrity of the functional material in response to external thermo-mechanical loading.
In this work, the onset of surface damage was assessed using nanoindentation techniques and could be correlated to weaker cleavage planes, where traces of plastic deformation (twinning) together with cracks on the contact surface were observed. Strength and fracture toughness of LiTaO3 and LiNbO3 were measured using biaxial bending on wafer samples of different orientations and in-situ SEM bending of notched micro-cantilevers loaded with a nanoindenter-tip, respectively. Experiments were supported by atomistic modelling, which could validate the experimental observations by calculating cleavage fracture energies.