Dielectric tunability and electro-optic effect of Ba0.5Sr0.5TiO3 thin films

Abstract

We elucidated the relationship between the dielectric tunability and the electro-optic (EO) effect. A new measurement system for EO effect and dielectric permittivity (εr) was developed to investigate the accurate correlation between EO and dielectric properties of epitaxial barium strontium titanate, Ba0.5Sr0.5TiO3 (BST) thin films grown on SrTiO3 (STO) substrates. The BST films had a strained lattice with a large lattice parameter along the thickness direction. Small birefringence was induced in the as-deposited film by the alignment of the c-axis in the film plane. The tunability of dielectric permittivity calculated from the complex voltage and current with planer electrodes reached to 53.1%, and the tunability of birefringence by EO effect was 0.6%. The birefringence change from EO effect was much lower than the tunability of dielectric permittivity. Therefore, there is no strong correlation between the dielectric tunability and EO effect, and the materials with high tunability do not always exhibit high EO effect. Finally, we discussed how to obtain the materials with high EO effect considering these results.

High electro-optic kerr effect in (Bi,K,Na)TiO₃ relaxor single crystals

“…The g values of the 33BKNT single crystal and other EO materials are listed in Table 2, which shows that the 33BKNT single crystal and lead lanthanum zirconate titanate ceramics exhibited a relatively high quadratic EO coefficient g. This tendency agrees well with our expectation in ref. [18], so we can conclude that the materials composed of heavy metal ions have high g values. Nevertheless, further discussion is necessary and underway.…”

“…The relaxor materials show higher EO coefficient compared to other dielectric or ferroelectric materials with the same dielectric permittivity. 10)16) Given Didomenico et al's observations and our previous report, 18) we conclude that relaxors composed of heavy ions will have a high EO coefficient.In this study, we focused on the Bi-based, perovskite-type, xBi 0.5 K 0.5 TiO 3 (1¹x) Bi 0.5 Na 0.5 TiO 3 (abbreviated as 100xBKNT) solid solution single crystal. Single crystals and ceramics have been intensively studied as potential lead-free piezoelectric materials.…”

“…The relaxor materials show higher EO coefficient compared to other dielectric or ferroelectric materials with the same dielectric permittivity. 10)16) Given Didomenico et al's observations and our previous report, 18) we conclude that relaxors composed of heavy ions will have a high EO coefficient.…”

“…In our previous report, 18) we discovered that EO materials with high EO coefficients have a tendency to indicate high dielectric permittivity. This tendency is explained by the equation for the quadratic EO effect, defined as…”

Tunable multifunctional magneto-optical devices based on magnetophotonic crystals comprising liquid crystal defect layers

“…For this reason, implementation of EO layers with their favorable physical properties which may be preferable in reaching electric tunability has been more common. 8,9 In fact, there is a variety of devices in operation that comprise electrically controllable EO layers. Furthermore, some interesting reports exist in the literature, which reveal electric tunability of LC-based 1D dielectric PCs.…”