Atomically resolved precipitates/matrix interfaces in KTaO3crystals

KTaO3 is an incipient ferroelectric with its properties influenced by defects and the purity. In this paper, we investigated the microstructures of KTaO3 by X-ray diffraction (XRD) and Cs-corrected scanning transmission electron microscopy (STEM). XRD and electron diffraction indicate that a second phase of K6Ta10.8O30 precipitates from the matrix. Four orientation relationships were identified: (100)m // ( 0)p, [001]m // [0 0 1]p; (1 0 0)m // ( 0)p, [001]m // [0 0 1]p; (1 0 0)m // (0 0 1)p, [0 0 1]m // [3 1 0]p and (100)m // ( 3 0)p, [0 0 1]m // [3 1 0]p. High resolution imaging shows that the interfaces between the second phase and KaTaO3 are distinct and coherent. Atomically resolved analysis identified two kinds of novel ordered defects at the interfaces with the termination planes either KO plane of KTaO3 or TaO2 plane of KTaO3.