Crystal structure and polarization hysteresis properties of ferroelectric BaTiO₃ thin-film capacitors on (Ba,Sr)TiO₃-buffered substrates

Abstract

Ferroelectric BaTiO3 (BT) thin-film capacitors with a buffer layer of (Ba1− x Sr x )TiO3 (BST) have been fabricated on (001) SrTiO3 (STO) single-crystal substrates by a pulsed laser deposition method, and the crystal structure and polarization hysteresis properties have been investigated. X-ray diffraction reciprocal space mapping shows that the BST buffer effectively reduces the misfit strain relaxation of the BT films on SrRuO3 (SRO) electrodes. The BT capacitor with the SRO electrodes on the BST (x = 0.3) buffer exhibits a well-saturated hysteresis loop with a remanent polarization of 29 µC/cm2. The hysteresis loop displays a shift toward a specific field direction, which is suggested to stem from the flexoelectric coupling between the out-of-plane polarization and the strain gradient adjacent to the bottom interface.

Polarization and Dielectric Properties of BiFeO3-BaTiO3 Superlattice-Structured Ferroelectric Films

“…The P - E loop exhibits an imprint, i.e., a shift in the negative E direction. This behavior is assumed to stem from a flexoelectric effect [ 29 , 40 , 41 ], where a strain gradient in the out-of-plane direction in the ferroelectric layer stabilizes the upward polarization compared with the downward one. Compared with the buffered electrode with a = 0.3986 nm, the BaTiO 3 layer has the same a , whereas the Mn-BiFeO 3 layer possesses a slightly small a = 0.3965 nm.…”

Crystal structure and ferroelectric polarization of tetragonal (Bi1/2Na1/2)TiO3–12BaTiO3

“…A perovskite solid solution of (1 − x)(Bi 1=2 Na 1=2 )TiO 3 -xBaTiO 3 (BNT-xBT) has been recognized as one of the most promising candidates for lead-free piezoelectric materials. [1][2][3][4][5][6][7][8][9][10][11][12] Because BNT [13][14][15][16][17][18] is a ferroelectric in rhombohedral R3c symmetry while BT [19][20][21][22][23][24][25][26][27][28] has a tetragonal ferroelectric in P4mm symmetry, a morphotropic phase boundary (MPB) is expected to lie in the BNT-BT system and plays a crucial role in the polarization and piezoelectric properties. The pioneering works by Takenaka et al have demonstrated that BNT-BT ceramics exhibit a superior piezoelectric response with a relatively high electromechanical coupling factor k 33 of over 50% at a BT composition (x) of ∼6%.…”