11 research outputs found
Nanoscale piezoelectric response across a single antiparallel ferroelectric domain wall
Surprising asymmetry in the local electromechanical response across a single
antiparallel ferroelectric domain wall is reported. Piezoelectric force
microscopy is used to investigate both the in-plane and out-of- plane
electromechanical signals around domain walls in congruent and
near-stoichiometric lithium niobate. The observed asymmetry is shown to have a
strong correlation to crystal stoichiometry, suggesting defect-domain wall
interactions. A defect-dipole model is proposed. Finite element method is used
to simulate the electromechanical processes at the wall and reconstruct the
images. For the near-stoichiometric composition, good agreement is found in
both form and magnitude. Some discrepancy remains between the experimental and
modeling widths of the imaged effects across a wall. This is analyzed from the
perspective of possible electrostatic contributions to the imaging process, as
well as local changes in the material properties in the vicinity of the wall
Ultrathin slices of ferroelectric domain-patterned lithium niobate by crystal ion slicing
We report the successful fabrication of 6 μm thick slices from a ferroelectric domain microengineered LiNbO3 wafer device using the crystal ion slicing technique. The device was created by micropatterning ferroelectric domains in a bulk 0.3 mm thick wafer of z-cut LiNbO3, followed by ion-implanting with 3.8 MeV He+ ions to a fluence 5 × 10+16 ions/cm2 to create a damage layer at a well defined depth from the surface. Etching away this damaged layer in dilute hydrofluoric acid results in a liftoff of the top slice in which the ferroelectric domain patterns are left intact. The influence of annealing conditions on liftoff time and depth of etch lines was studied. Helium-Neon laser light was successfully coupled into the device. Due to unintentional breakage of the polished input and output faces, the electro-optic scanning performance has not been characterized so far. © 2001 Materials Research Society
Recommended from our members
DETERMINING ELECTRO-OPTIC COEFFICIENTS FOR LITHIUM TANTALATE USING AN ELECTRO-OPTIC SCANNING DEVICE
Recommended from our members
Determining electro-optic coefficients for lithium tantalate using an electro-optic scanning device
We demonstrate a ferroelectric optical device based on single crystal LiTaO{sub 3} that can scan a laser beam from the visible to the infrared. It utilizes the electro-optic effect in the ferroelectric that has potentially high intrinsic response times of GHz. There are many applications to such scanning devices in the infrared such as optical switching, spectrometry, microscopy, and sensing. Lithium tantalate has two ferroelectric polarization states that are antiparallel (180{sup o}) to each other. The domain states can be reversed by applying an electric field of {approx}21 kV/mm at room temperature. By reversing the domain structure in the crystal, we can create domains in the crystal of almost any desired shape. By creating prism-shaped domain, we can create a ferroelectric deflector or scanner by applying either static or sweeping voltages across the crystal. This scanner is capable of scanning wavelengths from 0.4-5 {micro}m. The scanning performance varied from a total deflection angle of 13.38{sup o} at 1558 nm to 16.18{sup o} at 632.8 nm. Since the amount of deflection of the incoming light is determined by the applied voltage, the electro-optic coefficient and other fixed quantities, by measuring the deflection angle as a function of wavelength, the dispersion of the electro-optic coefficient in lithium tantalate can be determined. In these experiments, the scanner was characterized from the visible (632.8 nm) to midinfrared (1558 nm). Both extraordinary and the ordinary polarizations of light were used, in order to determine the electro-optic coefficients, r{sup 33} and r{sup 31}. Except for the values at 632.8 nm, these values of the electro-optic coefficients have not been previously reported. For lithium tantalate, r{sup 33} at 632.8 nm is reported in the literature as 30.2 pm/V. We found that this decreases to 27.1 pm/V at 1558 nm. For the extraordinary polarization, r{sup 13} varied from 7.55 pm/V (632.8 nm) to 6.84 pm/V (1558 nm)
Phenomenological theory of a single domain wall in uniaxial trigonal ferroelectrics: Lithium niobate and lithium tantalate
Room-Temperature Voltage Tunable Phonon Thermal Conductivity via Reconfigurable Interfaces in Ferroelectric Thin Films
Dynamic
control of thermal transport in solid-state systems is a transformative
capability with the promise to propel technologies including phononic
logic, thermal management, and energy harvesting. A solid-state solution
to rapidly manipulate phonons has escaped the scientific community.
We demonstrate active and reversible tuning of thermal conductivity
by manipulating the nanoscale ferroelastic domain structure of a PbÂ(Zr<sub>0.3</sub>Ti<sub>0.7</sub>)ÂO<sub>3</sub> film with applied electric
fields. With subsecond response times, the room-temperature thermal
conductivity was modulated by 11%
Local electromechanical response at a single ferroelectric domain wall in lithium niobate
Recommended from our members
Effect of Antidepressant Switching vs Augmentation on Remission Among Patients With Major Depressive Disorder Unresponsive to Antidepressant Treatment: The VAST-D Randomized Clinical Trial.
ImportanceLess than one-third of patients with major depressive disorder (MDD) achieve remission with their first antidepressant.ObjectiveTo determine the relative effectiveness and safety of 3 common alternate treatments for MDD.Design, setting, and participantsFrom December 2012 to May 2015, 1522 patients at 35 US Veterans Health Administration medical centers who were diagnosed with nonpsychotic MDD, unresponsive to at least 1 antidepressant course meeting minimal standards for treatment dose and duration, participated in the study. Patients were randomly assigned (1:1:1) to 1 of 3 treatments and evaluated for up to 36 weeks.InterventionsSwitch to a different antidepressant, bupropion (switch group, n = 511); augment current treatment with bupropion (augment-bupropion group, n = 506); or augment with an atypical antipsychotic, aripiprazole (augment-aripiprazole group, n = 505) for 12 weeks (acute treatment phase) and up to 36 weeks for longer-term follow-up (continuation phase).Main outcomes and measuresThe primary outcome was remission during the acute treatment phase (16-item Quick Inventory of Depressive Symptomatology-Clinician Rated [QIDS-C16] score ≤5 at 2 consecutive visits). Secondary outcomes included response (≥50% reduction in QIDS-C16 score or improvement on the Clinical Global Impression Improvement scale), relapse, and adverse effects.ResultsAmong 1522 randomized patients (mean age, 54.4 years; men, 1296 [85.2%]), 1137 (74.7%) completed the acute treatment phase. Remission rates at 12 weeks were 22.3% (n = 114) for the switch group, 26.9% (n = 136)for the augment-bupropion group, and 28.9% (n = 146) for the augment-aripiprazole group. The augment-aripiprazole group exceeded the switch group in remission (relative risk [RR], 1.30 [95% CI, 1.05-1.60]; P = .02), but other remission comparisons were not significant. Response was greater for the augment-aripiprazole group (74.3%) than for either the switch group (62.4%; RR, 1.19 [95% CI, 1.09-1.29]) or the augment-bupropion group (65.6%; RR, 1.13 [95% CI, 1.04-1.23]). No significant treatment differences were observed for relapse. Anxiety was more frequent in the 2 bupropion groups (24.3% in the switch group [n = 124] vs 16.6% in the augment-aripiprazole group [n = 84]; and 22.5% in augment-bupropion group [n = 114]). Adverse effects more frequent in the augment-aripiprazole group included somnolence, akathisia, and weight gain.Conclusions and relevanceAmong a predominantly male population with major depressive disorder unresponsive to antidepressant treatment, augmentation with aripiprazole resulted in a statistically significant but only modestly increased likelihood of remission during 12 weeks of treatment compared with switching to bupropion monotherapy. Given the small effect size and adverse effects associated with aripiprazole, further analysis including cost-effectiveness is needed to understand the net utility of this approach.Trial registrationclinicaltrials.gov Identifier: NCT01421342