The New Niobate Ba5NdTi3Nb7O30 was synthesized by solid state reaction at 1250℃ for 48h. The crystal structure and dielectric properties of Ba5NdTi3Nb7O30 were determined by X ray powder diffraction and dielectric me...The New Niobate Ba5NdTi3Nb7O30 was synthesized by solid state reaction at 1250℃ for 48h. The crystal structure and dielectric properties of Ba5NdTi3Nb7O30 were determined by X ray powder diffraction and dielectric measurements. The results show that Ba5NdTi3Nb7O30 belongs to ferroelectric phase of tetragonal tungsten bronze structure at room temperature with unit cell parameters: a=1.24424(4)nm, c=0.39476(2)nm, calculated density 5.719g·cm-3. Ba5NdTi3Nb7O30 belongs to relaxor ferroelectrics. The phase transition temperature (Tc) of Ba5NdTi3Nb7O30 from ferroelectric to paraelectric is found to shift toward higher temperature side at higher frequency, and Tc is 90℃ at 1kHz. At room temperature, the dielectric constant (εr) and dielectric loss of Ba5NdTi3Nb7O30 decrease with the increase of frequency, and Ba5NdTi3Nb7O30 ceramic have high dielectric constant 489 at 1kHz.展开更多
采用反应沉积外延法在723K的Si(111)衬底上共沉积了的Ba/Si混合膜,通过时间控制得到不同厚度的混合膜,然后真空退火处理。X射线衍射表明在真空中1073K退火12小时后出现了单一的Ba5Si3薄膜。采用第一性原理对Ba5Si3的能带结构进行了计算...采用反应沉积外延法在723K的Si(111)衬底上共沉积了的Ba/Si混合膜,通过时间控制得到不同厚度的混合膜,然后真空退火处理。X射线衍射表明在真空中1073K退火12小时后出现了单一的Ba5Si3薄膜。采用第一性原理对Ba5Si3的能带结构进行了计算,带隙宽度为0 e V,表现为金属性质。展开更多
文摘The New Niobate Ba5NdTi3Nb7O30 was synthesized by solid state reaction at 1250℃ for 48h. The crystal structure and dielectric properties of Ba5NdTi3Nb7O30 were determined by X ray powder diffraction and dielectric measurements. The results show that Ba5NdTi3Nb7O30 belongs to ferroelectric phase of tetragonal tungsten bronze structure at room temperature with unit cell parameters: a=1.24424(4)nm, c=0.39476(2)nm, calculated density 5.719g·cm-3. Ba5NdTi3Nb7O30 belongs to relaxor ferroelectrics. The phase transition temperature (Tc) of Ba5NdTi3Nb7O30 from ferroelectric to paraelectric is found to shift toward higher temperature side at higher frequency, and Tc is 90℃ at 1kHz. At room temperature, the dielectric constant (εr) and dielectric loss of Ba5NdTi3Nb7O30 decrease with the increase of frequency, and Ba5NdTi3Nb7O30 ceramic have high dielectric constant 489 at 1kHz.
