Periodic configuration of delta-boundaries and ferroelectric domains in Li-modified (K, Na)NbO3 lead-free piezoelectric single crystals by solid state crystal growth

摘要

(K0.45Na0.55)(0.94)Li0.06NbO3 (KNLN) lead-free piezoelectric single crystals have been prepared by solid-state crystal growth (SSCG) method using faceted KTaO3 single crystals as a seed. SEM-EBSD, PFM and TEM investigations revealed a specific periodic configuration of delta-boundaries and ferroelectric domains in the KNLN single crystal. The single crystal is sliced into several nearly parallel segments by delta-boundaries and each segment has a mean thickness of 2-3 mu m. Neighboring segments show a misorientation of 1.4 degrees/[1232] while the alternate segments have the same orientation. The two segments exhibit different ferroelectric domain structures: periodic (100) domain walls and (1 (1) over barl) domain walls, respectively. The periodic (100) domain wall pattern can be sketched by tetragonal 180 degrees or orthorhombic 90 degrees domains. The as-observed periodic configuration of small-angle delta-boundaries and ferroelectric domains could be related to the specific stress fields in the epitaxial crystal growth embedded in a ceramic matrix. (C) 2016 Elsevier Ltd. All rights reserved.