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
Neodymium-substituted bismuth titanate （Bi3NdTi3O12, BNT） thin films were prepared on quartz substrates by a metal-organic solution deposition process. The crystalline structure was evaluated by X-ray diffraction. W...Neodymium-substituted bismuth titanate （Bi3NdTi3O12, BNT） thin films were prepared on quartz substrates by a metal-organic solution deposition process. The crystalline structure was evaluated by X-ray diffraction. Waveguide property was investigated by using prism coupling technique and optical transmittance measurement. The optical nonlinearities of the film were measured by the top-hat Z-scan techniques and a large positive nonlinear refractive index, nonlinear refractive coefficient and two-photon absorption coefficient were determined to be 3.84×10^7 esu, 0.7523 cm^2/GW and 4.81×10^4 cm/GW, respectively. These results reveal that the BNT film may be a kind of new multifunctional materials.展开更多
Conjugated polymers are widely used in organic optoelectronic devices due to their solution processability, thermal stability and structural diversity. Generally, alkyl side chains must be utilized to increase the sol...Conjugated polymers are widely used in organic optoelectronic devices due to their solution processability, thermal stability and structural diversity. Generally, alkyl side chains must be utilized to increase the solubility of final polymers in the processing solvent. However, the effects of different type alkyl chains on the properties of n-type photovoltaic polymers have rarely been investigated. In this article, we synthesized three naphthodithiophene diimide（NDTI） based polymers containing bulky alkyl chains with different branching position, named as NDTI-1, NDTI-2 and NDTI-3, respectively. We systematically investigated the effect of different branching point on the molecular packing, charge transport and photovoltaic performance. When moving the branching point away from the backbone, the intermolecular interaction became stronger, which could be proved by 2D grazing incidence wide angle X-ray scattering（GIWAXS） measurement. Therefore, the electron mobilities in organic field-effect transistors gradually increased from 2.11×10-3 cm2 V/-1 s-1 for NDTI-1 to 4.70×10-2 cm2 V/-1 s-1 for NDTI-2 and 9.27×10-2 cm2 V/-1 s-1 for NDTI-3,which are quite high values for polymers with face-on orientation. In addition, the NDTI-2 and NDTI-3 thin films exhibited redshifted absorption spectra compared with NDTI-1. When blending with three classic donor polymers PBDB-T, PTB7-Th and PE61, NDTI-2 based devices always showed the higher power conversion efficiencies（PCEs） than the other two polymers（beside the comparable result of PTB7-Th:NDTI-3 combination） as a result of the high photocurrent response and high fill factor. Our results indicate that bulky alkyl chain with branching point at 2-position should be a good and safe choice for the design of naphthodithiophene diimide-based and even naphthalene diimide-based n-type photovoltaic polymers.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.
文摘Neodymium-substituted bismuth titanate （Bi3NdTi3O12, BNT） thin films were prepared on quartz substrates by a metal-organic solution deposition process. The crystalline structure was evaluated by X-ray diffraction. Waveguide property was investigated by using prism coupling technique and optical transmittance measurement. The optical nonlinearities of the film were measured by the top-hat Z-scan techniques and a large positive nonlinear refractive index, nonlinear refractive coefficient and two-photon absorption coefficient were determined to be 3.84×10^7 esu, 0.7523 cm^2/GW and 4.81×10^4 cm/GW, respectively. These results reveal that the BNT film may be a kind of new multifunctional materials.
基金supported by the National Key Research and Development Program of China (2017YFA0206600)the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (QYZDB-SSW-SLH033)the National Natural Science Foundation of China (51673048, 21875052)
文摘Conjugated polymers are widely used in organic optoelectronic devices due to their solution processability, thermal stability and structural diversity. Generally, alkyl side chains must be utilized to increase the solubility of final polymers in the processing solvent. However, the effects of different type alkyl chains on the properties of n-type photovoltaic polymers have rarely been investigated. In this article, we synthesized three naphthodithiophene diimide（NDTI） based polymers containing bulky alkyl chains with different branching position, named as NDTI-1, NDTI-2 and NDTI-3, respectively. We systematically investigated the effect of different branching point on the molecular packing, charge transport and photovoltaic performance. When moving the branching point away from the backbone, the intermolecular interaction became stronger, which could be proved by 2D grazing incidence wide angle X-ray scattering（GIWAXS） measurement. Therefore, the electron mobilities in organic field-effect transistors gradually increased from 2.11×10-3 cm2 V/-1 s-1 for NDTI-1 to 4.70×10-2 cm2 V/-1 s-1 for NDTI-2 and 9.27×10-2 cm2 V/-1 s-1 for NDTI-3,which are quite high values for polymers with face-on orientation. In addition, the NDTI-2 and NDTI-3 thin films exhibited redshifted absorption spectra compared with NDTI-1. When blending with three classic donor polymers PBDB-T, PTB7-Th and PE61, NDTI-2 based devices always showed the higher power conversion efficiencies（PCEs） than the other two polymers（beside the comparable result of PTB7-Th:NDTI-3 combination） as a result of the high photocurrent response and high fill factor. Our results indicate that bulky alkyl chain with branching point at 2-position should be a good and safe choice for the design of naphthodithiophene diimide-based and even naphthalene diimide-based n-type photovoltaic polymers.
