Observation of Ferroelastic and Ferroelectric Domains in AgNbO_3 Single Crystal

Compared to AgNbO_3 based ceramics, the experimental investigations on the single crystalline AgNbO_3, especially the ground state and ferroic domain structures, are not on the same level. Here, based on successfully synthesized AgNbO_3 single crystal using a flux method, we observed the coexistence of ferroelastic and ferroelectric domain structures by a combination study of polarized light microscopy and piezoresponse force microscopy. This finding may provide a new aspect for studying AgNbO_3. The result also suggests a weak electromechanical response from the ferroelectric phase of AgNbO_3, which is also supported by the transmission electron microscope characterization. Our results reveal that the AgNbO_3 single crystal is in a polar ferroelectric phase at room temperature, clarifying its ground state which is controversial from the AgNbO_3 ceramic materials.