Orthorhombic YFeO_3 thin film was prepared on La_(0.67)Sr_(0.33)MnO_3/LaAlO_3 substrate by a sol-gel spin-coating method. The structures of the YFeO_3/La_(0.67)Sr_(0.33)MnO_3/LaAlO_3(YFO/LSMO/LAO) sample were detected...Orthorhombic YFeO_3 thin film was prepared on La_(0.67)Sr_(0.33)MnO_3/LaAlO_3 substrate by a sol-gel spin-coating method. The structures of the YFeO_3/La_(0.67)Sr_(0.33)MnO_3/LaAlO_3(YFO/LSMO/LAO) sample were detected by x-ray diffraction pattern, Raman spectrometer, scanning electron microscopy, and atomic force microscope. The local ferroelectric polarization switching properties of the orthorhombic YFO film were confirmed by piezoresponse force microscopy(PFM) for the first time. The results show that the YFO film deposited on LSMO/LAO possesses orthorhombic structure,with ultra-fine crystal grains and flat surface. The leakage current of the YFO film is 8.39 × 10^(-4) A·cm^(-2) at 2 V,with its leakage mechanism found to be an ohmic behavior. PFM measurements indicate that the YFO film reveals weak ferroelectricity at room temperature and the local switching behavior of ferroelectric domains has been identified. By local poling experiment, polarization reversal in the orthorhombic YFO film at room temperature was further observed.展开更多
The transparency,reflectivity and color for electro-chromic(EC)materials can be changed reversibly under low bias[1].EC materials find wide application in many fields like microelectronics,energy-saving buildings,auto...The transparency,reflectivity and color for electro-chromic(EC)materials can be changed reversibly under low bias[1].EC materials find wide application in many fields like microelectronics,energy-saving buildings,automobiles,na-tional defense and aerospace industry[2].Compared with inor-ganic EC materials,organic EC materials have advantages like easy modification of molecular structures,rich color changes and fast-switching speed[3].展开更多
The scalable production of high grade activated carbon from abundant coal for supercapacitors application is an efficient way to achieve high value-added utilization of coal sources.However,this technology is challeng...The scalable production of high grade activated carbon from abundant coal for supercapacitors application is an efficient way to achieve high value-added utilization of coal sources.However,this technology is challenging due to lack of comprehensive understanding on the mechanism of activation process and effect of external factors.In this paper,the effect of activating temperature and time on the specific capacitance of coal-based activated carbon prepared by H2O steam activation was studied using the response surface method.Under optimal conditions,coal-based activated carbon exhibits the largest specific capacitance of 194.35 F·g^(−1),thanks to the appropriate pore/surface structure and defect degree.Density functional theory calculations explain in detail the mechanism of contraction of aromatic rings and overflow of H2 and CO during the activation.Meanwhile,oxygen-containing functional groups are introduced,contributing to the pseudocapacitance property of coal-based activated carbon.This mechanism of reactions between aromatic carbon and H2O vapor provides understanding on the role of water during coal processing at the molecular level,offering great potential to regulate product distribution and predict rate of pore generation.This insight would contribute to the advancement of other coal processing technology such as gasification.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.61471301)Natural Science Basic Research Program of Shaanxi,China(Grant No.2017JQ5083)PhD Research Startup Foundation of Xi’an University of Science and Technology,China(Grant No.2017QDJ044)
文摘Orthorhombic YFeO_3 thin film was prepared on La_(0.67)Sr_(0.33)MnO_3/LaAlO_3 substrate by a sol-gel spin-coating method. The structures of the YFeO_3/La_(0.67)Sr_(0.33)MnO_3/LaAlO_3(YFO/LSMO/LAO) sample were detected by x-ray diffraction pattern, Raman spectrometer, scanning electron microscopy, and atomic force microscope. The local ferroelectric polarization switching properties of the orthorhombic YFO film were confirmed by piezoresponse force microscopy(PFM) for the first time. The results show that the YFO film deposited on LSMO/LAO possesses orthorhombic structure,with ultra-fine crystal grains and flat surface. The leakage current of the YFO film is 8.39 × 10^(-4) A·cm^(-2) at 2 V,with its leakage mechanism found to be an ohmic behavior. PFM measurements indicate that the YFO film reveals weak ferroelectricity at room temperature and the local switching behavior of ferroelectric domains has been identified. By local poling experiment, polarization reversal in the orthorhombic YFO film at room temperature was further observed.
基金the National Natural Science Foundation of China (52073227)the open research fund of Songshan Lake Materials Laboratory (2021SLABFK02)+1 种基金the National Key Research and Development Program of China(2017YFA0206600)the National Natural Science Foundation of China (51922032,21961160720)
文摘The transparency,reflectivity and color for electro-chromic(EC)materials can be changed reversibly under low bias[1].EC materials find wide application in many fields like microelectronics,energy-saving buildings,automobiles,na-tional defense and aerospace industry[2].Compared with inor-ganic EC materials,organic EC materials have advantages like easy modification of molecular structures,rich color changes and fast-switching speed[3].
基金support by Shaanxi Province Technological Innovation Guidance Special (Grant No.2021QFY04-01)technical support by Analytical Instrumentation Center of XUST.
文摘The scalable production of high grade activated carbon from abundant coal for supercapacitors application is an efficient way to achieve high value-added utilization of coal sources.However,this technology is challenging due to lack of comprehensive understanding on the mechanism of activation process and effect of external factors.In this paper,the effect of activating temperature and time on the specific capacitance of coal-based activated carbon prepared by H2O steam activation was studied using the response surface method.Under optimal conditions,coal-based activated carbon exhibits the largest specific capacitance of 194.35 F·g^(−1),thanks to the appropriate pore/surface structure and defect degree.Density functional theory calculations explain in detail the mechanism of contraction of aromatic rings and overflow of H2 and CO during the activation.Meanwhile,oxygen-containing functional groups are introduced,contributing to the pseudocapacitance property of coal-based activated carbon.This mechanism of reactions between aromatic carbon and H2O vapor provides understanding on the role of water during coal processing at the molecular level,offering great potential to regulate product distribution and predict rate of pore generation.This insight would contribute to the advancement of other coal processing technology such as gasification.