RESUMO
Investigations concerning oxygen deficiency will increase our understanding of those factors that govern the overall material properties. Various studies have examined the relationship between oxygen deficiency and the phase transformation from a nonpolar phase to a polar phase in HfO2 thin films. However, there are few reports on the effects of oxygen deficiencies on the switching dynamics of the ferroelectric phase itself. Herein, we report the oxygen- deficiency induced enhancement of ferroelectric switching properties of Si-doped HfO2 thin films. By controlling the annealing conditions, we controlled the oxygen deficiency concentration in the ferroelectric orthorhombic HfO2 phase. Rapid high-temperature (800 °C) annealing of the HfO2 film accelerated the characteristic switching speed compared to low-temperature (600 °C) annealing. Scanning transmission electron microscopy and electron energy-loss spectroscopy (EELS) revealed that thermal annealing increased oxygen deficiencies, and first-principles calculations demonstrated a reduction of the energy barrier of the polarization flip with increased oxygen deficiency. A Monte Carlo simulation for the variation in the energy barrier of the polarization flipping confirmed the increase of characteristic switching speed.
RESUMO
Microtia reconstructive surgery is usually a multi-stage repair procedure that involves the use of cartilage and skin grafts. Complications can arise at both ear reconstruction sites and cartilage donor sites. In particular, pneumothorax, atelectasis, chest scars, and chest deformities are known to be associated with the harvesting of costal cartilage. However, delayed pleural effusion can also develop. Our patient complained of a cough and chest pain at 5 days postoperatively, and pleural effusion was detected by chest radiography. However, thoracentesis was not performed and the effusion resolved spontaneously and completely.
