The anti-resonant phenomenon of effective electromagnetic parameters of metamaterials has aroused controversy due to negative imaginary permittivity or permeability. It is experimentally found that the negative imagin...The anti-resonant phenomenon of effective electromagnetic parameters of metamaterials has aroused controversy due to negative imaginary permittivity or permeability. It is experimentally found that the negative imaginary permittivity can occur for the natural passive materials near the Fabry Perot resonances. We reveal the nature of negative imaginary permittivity, which is correlated with the magnetoelectric coupling. The anti-resonance of permittivity is a non-inherent feature for passive materials, while it can be inherent for devices or metamaterials. Our finding validates that the negative imaginary part of effective permittivity does not contradict the second law of thermodynamics for metamaterials owing to the magnetoelectric coupling.展开更多
In this paper, we study the static dielectric function and interaction potential in strong coupling limit with AdS/CFT correspondence. The dielectric function is depressed compared with that in weak coupling. The inte...In this paper, we study the static dielectric function and interaction potential in strong coupling limit with AdS/CFT correspondence. The dielectric function is depressed compared with that in weak coupling. The interaction potential then presents a weaker screening characteristics in strong coupling, which indicates a smaller Debye mass compared with weak coupling.展开更多
利用脉冲激光沉积技术在Sr Ti O_3表面导电层上方制备非晶Hf O_2栅介质薄膜,通过磁控溅射技术在非晶Hf O_2栅介质薄膜上方制备直径为100μm的圆形Pt电极,研究了变温条件下Pt/Hf O_2/Sr Ti O_3的漏电流I-V特性,分析了非晶Hf O_2栅介质层...利用脉冲激光沉积技术在Sr Ti O_3表面导电层上方制备非晶Hf O_2栅介质薄膜,通过磁控溅射技术在非晶Hf O_2栅介质薄膜上方制备直径为100μm的圆形Pt电极,研究了变温条件下Pt/Hf O_2/Sr Ti O_3的漏电流I-V特性,分析了非晶Hf O_2栅介质层的漏电机制,如空间电荷限制电流机制、Fowler-Nordheim导电机制、Pool-Frenkel发射机制、肖特基发射机制。研究结果表明在低压段(<0.18 V)为欧姆导电;在高压段(>0.5 V)为Pool-Frenkel发射机制。展开更多
采用流延法成功制备了无铅弛豫铁电0.65(0.65Na 0.5 Bi 0.5 TiO 3-0.35BiMg 0.5 Ti 0.5 O 3)-0.35SrTiO 3陶瓷.研究了陶瓷的微观形貌、相结构、介电性能和储能行为.并在连续升温环境下,探讨了陶瓷的储能密度和储能效率的稳定性.结果表明...采用流延法成功制备了无铅弛豫铁电0.65(0.65Na 0.5 Bi 0.5 TiO 3-0.35BiMg 0.5 Ti 0.5 O 3)-0.35SrTiO 3陶瓷.研究了陶瓷的微观形貌、相结构、介电性能和储能行为.并在连续升温环境下,探讨了陶瓷的储能密度和储能效率的稳定性.结果表明:该陶瓷为纯钙钛矿赝立方结构且结晶性良好,晶粒分布均匀,并且该陶瓷表现出良好的储能性能及温度稳定性.陶瓷在275 kV/cm电场下获得了最大的储能密度3.55 J/cm 3,相应的储能效率为72.8%.在30~140℃间,储能密度最大变化率为6.4%.此研究表明0.65(0.65Na 0.5 Bi 0.5 TiO 3-0.35BiMg 0.5 Ti 0.5 O 3)-0.35SrTiO 3陶瓷在储能方向具有很大的潜力,且将推动无铅介电储能材料在实际中的应用.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 51102007the Fund for Discipline Construction of Beijing University of Chemical Technology under Grant No XK1702
文摘The anti-resonant phenomenon of effective electromagnetic parameters of metamaterials has aroused controversy due to negative imaginary permittivity or permeability. It is experimentally found that the negative imaginary permittivity can occur for the natural passive materials near the Fabry Perot resonances. We reveal the nature of negative imaginary permittivity, which is correlated with the magnetoelectric coupling. The anti-resonance of permittivity is a non-inherent feature for passive materials, while it can be inherent for devices or metamaterials. Our finding validates that the negative imaginary part of effective permittivity does not contradict the second law of thermodynamics for metamaterials owing to the magnetoelectric coupling.
基金Supported by National Natural Science Foundation of China under Grant No.10947002
文摘In this paper, we study the static dielectric function and interaction potential in strong coupling limit with AdS/CFT correspondence. The dielectric function is depressed compared with that in weak coupling. The interaction potential then presents a weaker screening characteristics in strong coupling, which indicates a smaller Debye mass compared with weak coupling.
文摘采用流延法成功制备了无铅弛豫铁电0.65(0.65Na 0.5 Bi 0.5 TiO 3-0.35BiMg 0.5 Ti 0.5 O 3)-0.35SrTiO 3陶瓷.研究了陶瓷的微观形貌、相结构、介电性能和储能行为.并在连续升温环境下,探讨了陶瓷的储能密度和储能效率的稳定性.结果表明:该陶瓷为纯钙钛矿赝立方结构且结晶性良好,晶粒分布均匀,并且该陶瓷表现出良好的储能性能及温度稳定性.陶瓷在275 kV/cm电场下获得了最大的储能密度3.55 J/cm 3,相应的储能效率为72.8%.在30~140℃间,储能密度最大变化率为6.4%.此研究表明0.65(0.65Na 0.5 Bi 0.5 TiO 3-0.35BiMg 0.5 Ti 0.5 O 3)-0.35SrTiO 3陶瓷在储能方向具有很大的潜力,且将推动无铅介电储能材料在实际中的应用.