3 research outputs found
Imaging Ferroelectric Domains and Domain Walls Using Charge Gradient Microscopy: Role of Screening Charges
Advanced scanning probe microscopies
(SPMs) open up the possibilities
of the next-generation ferroic devices that utilize both domains and
domain walls as active elements. However, current SPMs lack the capability
of dynamically monitoring the motion of domains and domain walls in
conjunction with the transport of the screening charges that lower
the total electrostatic energy of both domains and domain walls. Charge
gradient microscopy (CGM) is a strong candidate to overcome these
shortcomings because it can map domains and domain walls at high speed
and mechanically remove the screening charges. Yet the underlying
mechanism of the CGM signals is not fully understood due to the complexity
of the electrostatic interactions. Here, we designed a semiconductor–metal
CGM tip, which can separate and quantify the ferroelectric domain
and domain wall signals by simply changing its scanning direction.
Our investigation reveals that the domain wall signals are due to
the spatial change of polarization charges, while the domain signals
are due to continuous removal and supply of screening charges at the
CGM tip. In addition, we observed asymmetric CGM domain currents from
the up and down domains, which are originated from the different debonding
energies and the amount of the screening charges on positive and negative
bound charges. We believe that our findings can help design CGM with
high spatial resolution and lead to breakthroughs in information storage
and energy-harvesting devices
Additional file 1 of The clinical effectiveness of fused image of single-photon emission CT and facial CT for the evaluation of degenerative change of mandibular condylar head
Additional file 1: Supplemental Table. Groups according to the clinical and radiographic findings, and values and comparison of 99mTc-MDP uptake ratio of the group
Enhancement of Local Piezoresponse in Polymer Ferroelectrics <i>via</i> Nanoscale Control of Microstructure
Polymer ferroelectrics are flexible and lightweight electromechanical materials that are widely studied due to their potential application as sensors, actuators, and energy harvesters. However, one of the biggest challenges is their low piezoelectric coefficient. Here, we report a mechanical annealing effect based on local pressure induced by a nanoscale tip that enhances the local piezoresponse. This process can control the nanoscale material properties over a microscale area at room temperature. We attribute this improvement to the formation and growth of β-phase extended chain crystals <i>via</i> sliding diffusion and crystal alignment along the scan axis under high mechanical stress. We believe that this technique can be useful for local enhancement of piezoresponse in ferroelectric polymer thin films