Mechanical behaviour of Li3La1/3−NbO3 with domain structure

• Mechanical behaviours of Li 3 x La 1/3− x NbO 3 (3 x = 0.00–0.18) with domain structures. • Orthorhombic LLNbO reveals non-linear elastic hysteresis due to domain reorientations. • Tetragonal LLNbO reveals simple elastic behaviour with almost no domain change. This study investigates the mechanical behaviours of A-site deficient perovskite-type Li 3 x La 1/3− x NbO 3 electrolytes (3 x = 0.00–0.18) with domain structures. The samples were examined under uniaxial compression in the temperature range of 233–393 K. In the stress vs. strain relationship, the orthorhombic Li 3 x La 1/3− x NbO 3 (3 x ≤ 0.06) clearly exhibits non-linear elastic hysteresis, whilst the tetragonal one (3 x ≥ 0.12) shows a simple elastic behaviour. Ex-situ scanning electron microscopy observation on a polished surface before and after compression confirmed the martensitic reorientation of the domain structure of the orthorhombic Li 3 x La 1/3− x NbO 3 , which explains the observed non-linear hysteresis, whereas the domains of the tetragonal sample remain almost unchanged.