Multifunctionality of Li2SrNb2O7: Memristivity, Tunable Rectification, Ferroelasticity, and Ferroelectricity

Layered Li2SrNb2O7, an inorganic oxide in its bulk single‐crystalline form, is experimentally demonstrated to exhibit multiple structural facets such as ferroelasticity, ferroelectricity, and antiferroelectricity. The transition from a room temperature (RT) centrosymmetric structure to a low‐temperature out‐of‐plane ferroelectric and in‐plane antiferroelectric structure and the low‐temperature (LT) ferroelectric domain configuration are unveiled in TEM, piezoresponse force microscopy, and polarization loop studies. Li2SrNb2O7 also exhibits highly tunable ferroelasticity and excellent Li+ in‐plane conduction, which leads to a giant in‐plane memristor behavior and an in‐plane electronic conductivity increase by three orders of magnitude by electric poling at room RT). The accumulation of Li+ vacancies at the crystal–electrode interface is visualized using in situ optical microscopy. The Li‐ionic biased state shows a clear in‐plane rectification effect combined with a significant relaxation upon time at RT. Relaxation can be fully suppressed at LTs such as 200 K, and utilizing an electric field cooling, a stable rectification can be achieved at 200 K. The results shed light on the selective control of multifunctionalities such as ferroelasticity, ferroelectricity, and ionic‐migration‐mediated effects (a memristor effect and rectification) in a single‐phase bulk material utilizing, for example, different directions, temperatures, frequencies, and magnitudes of electric field. Layered perovskite Li2SrNb2O7 bulk single crystals are synthesized. At room temperature, Li ions show significant intralayer activities, which creates a giant memristivity and a rectification effect combining with a relaxation upon time. At low temperature, out‐of‐plane ferroelectricity and in‐plane antiferroelectricity develop, and the rectification state becomes robust. The results demonstrate a selectively controlling of the ferroic orders and ionic migration.