Compatibilization mechanisms of nanoclays with different surface modifiers in UCST blends: Opposing effects on phase miscibility

Polymer ◽  
2014 ◽  
Vol 55 (25) ◽  
pp. 6623-6633 ◽  
Author(s):  
Farkhondeh Hemmati ◽  
Hamid Garmabi ◽  
Hamid Modarress
Keyword(s):  
Surface Modifiers ◽  
Opposing Effects

scholarly journals Alkali-deficiency driven charged out-of-phase boundaries for giant electromechanical response

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Haijun Wu ◽  
Shoucong Ning ◽  
Moaz Waqar ◽  
Huajun Liu ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Temperature Stability ◽  
Epitaxial Films ◽  
Polarization Rotation ◽  
Phase Boundaries ◽  
Film Properties ◽  
New Strategy ◽  
The Matrix ◽  
Opposing Effects ◽  
Severe Deterioration

AbstractTraditional strategies for improving piezoelectric properties have focused on phase boundary engineering through complex chemical alloying and phase control. Although they have been successfully employed in bulk materials, they have not been effective in thin films due to the severe deterioration in epitaxy, which is critical to film properties. Contending with the opposing effects of alloying and epitaxy in thin films has been a long-standing issue. Herein we demonstrate a new strategy in alkali niobate epitaxial films, utilizing alkali vacancies without alloying to form nanopillars enclosed with out-of-phase boundaries that can give rise to a giant electromechanical response. Both atomically resolved polarization mapping and phase field simulations show that the boundaries are strained and charged, manifesting as head-head and tail-tail polarization bound charges. Such charged boundaries produce a giant local depolarization field, which facilitates a steady polarization rotation between the matrix and nanopillars. The local elastic strain and charge manipulation at out-of-phase boundaries, demonstrated here, can be used as an effective pathway to obtain large electromechanical response with good temperature stability in similar perovskite oxides.

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