Domain reversal and nonstoichiometry in lithium tantalate

Abstract

Recent studies have shown that lithium nonstoichiometry has a tremendous influence on domain reversal characteristics in ferroelectric lithium tantalate. This work presents a systematic study of the domain reversal characteristics such as threshold coercive fields for domain reversal, domain stabilization times, ''backswitching'' phenomena, domain switching and wall pinning times, and sideways wall mobility in near-stoichiometric LiTaO 3 with Li/͑LiϩTa͒ϳ0.498. These properties are contrasted with those of congruent LiTaO 3 ͓Li/͑LiϩTa͒ϳ0.485͔. A qualitative model is proposed based on nonstoichiometric dipolar defects to explain the dependence of threshold coercive field on defect density, and on repeated field cycling, the origin of domain backswitching, and domain stabilization times.

Influence of annealing on the photodeposition of silver on periodically poled lithium niobate

“…28 Congruent LN is Li deficient, leading to nonstoichiometric defect clusters comprising one Nb antisite (Nb Li ) and four Li vacancies (V Li ), 29 which possess a polarization and a corresponding defect field that aligns with the depolarization field during crystal growth. 30 As described by Gopalan et al, upon poling, the Nb Li antisites show the same behavior as Li ions and move through the oxygen plane to the second thermodynamically stable position in the neighboring octahedron. 31 However, due to the low mobility of Li þ at room temperature, 32 the positions of the V Li remain the same, leaving the polar orientation of the defect cluster in the poled region in a frustrated state.…”

“…as grown crystal become antiparallel in the poled domain after poling. [27][28][29][30][32][33][34] Annealing the crystal at temperatures >150 C is known to mobilize Li þ ions, allowing the internal defect field to realign parallel to the depolarization field, thus alleviating the defect frustration. 35,36 Annealing therefore provides a mechanism to modify the internal defect field and by extension, the photodeposition.…”

Radiation-damage-assisted ferroelectric domain structuring in magnesium-doped lithium niobate

“…Nonetheless, PFM imaging is not hampered by the inhomogeneous field [20], yielding distinct differences in the poling process: in the irradiated region of the crystal the domains always grow in regular shaped hexagons whereas in the non-irradiated part the domain structures are distinctly less hexagonally shaped and rather circular. According to the defect dipole model for LiNbO 3 [21] the domain wall motion and stabilization can be explained by pinning at defects. Thus, the hexagons are very likely stabilized via defects introduced by the 3 He ion irradiation.…”

Dynamic processes of domain switching in lead zirconate titanate under cyclic mechanical loading by in situ neutron diffraction

“…The second component is the viscous force represented by internal friction (F f ). For ferroelectric/ferroelastic ceramics, the internal friction may be caused by the interaction between the point defects which possess an electrical dipole, and domains which have spontaneous polarization [34][35][36]. This may lead to a decrease in domain switchability under cyclic loading.…”