With the tunable and flexible physicochemical properties, tantalate photocatalysts with tungsten bronze struc- ture are worth being studied. In this work, we successfully synthesized a novel potassium tantalate K6Talo...With the tunable and flexible physicochemical properties, tantalate photocatalysts with tungsten bronze struc- ture are worth being studied. In this work, we successfully synthesized a novel potassium tantalate K6Talo.8030 with tungsten bronze structure using a facile solid-state reaction route. The effects of calcination time on the phase com- position, morphology and crystallinity of the obtained samples were studied by XRD and SEM analyses. In addition, the photocatalytic activity of the samples was evaluated by the degradation of ARG dye under UV light irradiation. The results indicated that the K6Talo.8030 showed high photocatalytic activity for degradation of ARG and the pho- tocatalytic degradation of ARG followed the first order kinetics. Furthermore, the possible photocatalytic mecha- nism of the K6TamsO30 photocatalyst was proposed based on tungsten bronze structure feature and the scavengers experimental results. This study would give a new insight into tantalate photocatalysts.展开更多
Recently,funds and corporations have adopted environmental/social/governance(ESG)-related criteria as increasingly important criteria when evaluating investments.The ESG scores of mutual funds,which pool money from ma...Recently,funds and corporations have adopted environmental/social/governance(ESG)-related criteria as increasingly important criteria when evaluating investments.The ESG scores of mutual funds,which pool money from many individuals,are,therefore,significant as a sign of social commitment and deliver long-term results for investors deciding in which fund to invest.However,this scoring process is not transparent,and computing ESG scores requires an extensive review and monitoring of accountancy data.In this study,Machine Learning(ML)was employed to predict six ESG scores of 3192 mutual funds by comparing the performance of the models built solely using 13 variables of ESG-controversial sectorial involvement and 37 variables of financial data.In both cases,three classification and three regression algorithms were applied to the 72 simulations.The results demonstrate an acceptable fit of the Random Forest and Gradient Boosting algorithms in regression exercises(R2 values of 60–80%)and good prediction capabilities for classification(accuracies of approximately 70–80%).The models obtained similar performance when predicting ESG scores either from financial data or ESG-controversial sectorial involvement,illustrating how financial variables are good predictors of ESG scores as data on direct involvement in non-ESG funds’activities.Thus,a relationship between the financial performance of a fund and its ESG score exists and is predictable by ML,saving time and resources.展开更多
Three novel dielectric ceramics Ba5LnZnNb9O30 (Ln= La, Nd and Sm) were synthesized and characterized in the BaO-Ln2O3-ZnO-Nb2O5 quaternary system, which formed the filled tungsten-bronze structures. The present cerami...Three novel dielectric ceramics Ba5LnZnNb9O30 (Ln= La, Nd and Sm) were synthesized and characterized in the BaO-Ln2O3-ZnO-Nb2O5 quaternary system, which formed the filled tungsten-bronze structures. The present ceramics exhibit high dielectric constant (εr) up to 310, low dielectric loss in the level of 10 3 at 1 MHz. Meanwhile, the temperature coefficients of the dielectric constant (τε) of Ba5LnZnNb9O3o varies from -1 390×10-6 to -1 220×10-6/℃as the radius of Ln3+ increases. The present ceramics are promising candidates for high dielectric constant and low loss dielectric ceramics.展开更多
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
Two compounds Ba 6 Zn 0.67 Nb 9.33 O 3 and Ba 6 Zn 0.67 Ta 9.33 O 30 with tungsten bronze structure were synthesized in the BaO-ZnO-Nb 2 O 5 /Ta 2 O 5 systems by the conventional high temperature solid-state reaction....Two compounds Ba 6 Zn 0.67 Nb 9.33 O 3 and Ba 6 Zn 0.67 Ta 9.33 O 30 with tungsten bronze structure were synthesized in the BaO-ZnO-Nb 2 O 5 /Ta 2 O 5 systems by the conventional high temperature solid-state reaction.The stru cture and dielectric properties of Ba 6 Zn 0.67 Nb 9.33 O 3 and Ba 6 Zn 0.67 Ta 9.33 O 30 were determined by X-ray powder diffraction,scanning electron microscope a nd dielectric measurements.The results show that Ba 6 Zn 0.67 Ta 9.33 O 30 belongs to paraelectric phase of fully filled tetragonal tungsten bronze str ucture at room temperature with unit cell parameters a=1.26256(4)nm, c=0.39698(2)nm.The room temperature dielectric constant( ε )of Ba 6 Zn 0.67 Ta 9.33 O 30 ceramic reached108combined with a low dielectric loss of0.005at1MHz .While Ba 6 Zn 0.67 Nb 9.33 O 3 belongs to fully filled tetragonal tungsten bronze structure at room tempera ture with the unit cell parameters a=1.25940(3)nm,c=0.40008 (2)nm.Ba 6 Zn 0.67 Nb 9.33 O 30 ceramic shows significant relaxor behaviors,and the phase transition from f erroelectric to paraelectric occurred at55℃(at1MHz).The room temperature dielectric constant( ε )of ceramic reached570at1MHz.展开更多
文摘With the tunable and flexible physicochemical properties, tantalate photocatalysts with tungsten bronze struc- ture are worth being studied. In this work, we successfully synthesized a novel potassium tantalate K6Talo.8030 with tungsten bronze structure using a facile solid-state reaction route. The effects of calcination time on the phase com- position, morphology and crystallinity of the obtained samples were studied by XRD and SEM analyses. In addition, the photocatalytic activity of the samples was evaluated by the degradation of ARG dye under UV light irradiation. The results indicated that the K6Talo.8030 showed high photocatalytic activity for degradation of ARG and the pho- tocatalytic degradation of ARG followed the first order kinetics. Furthermore, the possible photocatalytic mecha- nism of the K6TamsO30 photocatalyst was proposed based on tungsten bronze structure feature and the scavengers experimental results. This study would give a new insight into tantalate photocatalysts.
文摘Recently,funds and corporations have adopted environmental/social/governance(ESG)-related criteria as increasingly important criteria when evaluating investments.The ESG scores of mutual funds,which pool money from many individuals,are,therefore,significant as a sign of social commitment and deliver long-term results for investors deciding in which fund to invest.However,this scoring process is not transparent,and computing ESG scores requires an extensive review and monitoring of accountancy data.In this study,Machine Learning(ML)was employed to predict six ESG scores of 3192 mutual funds by comparing the performance of the models built solely using 13 variables of ESG-controversial sectorial involvement and 37 variables of financial data.In both cases,three classification and three regression algorithms were applied to the 72 simulations.The results demonstrate an acceptable fit of the Random Forest and Gradient Boosting algorithms in regression exercises(R2 values of 60–80%)and good prediction capabilities for classification(accuracies of approximately 70–80%).The models obtained similar performance when predicting ESG scores either from financial data or ESG-controversial sectorial involvement,illustrating how financial variables are good predictors of ESG scores as data on direct involvement in non-ESG funds’activities.Thus,a relationship between the financial performance of a fund and its ESG score exists and is predictable by ML,saving time and resources.
基金Projects(50572078 20571059) supported by the National Natural Science Foundation of China
文摘Three novel dielectric ceramics Ba5LnZnNb9O30 (Ln= La, Nd and Sm) were synthesized and characterized in the BaO-Ln2O3-ZnO-Nb2O5 quaternary system, which formed the filled tungsten-bronze structures. The present ceramics exhibit high dielectric constant (εr) up to 310, low dielectric loss in the level of 10 3 at 1 MHz. Meanwhile, the temperature coefficients of the dielectric constant (τε) of Ba5LnZnNb9O3o varies from -1 390×10-6 to -1 220×10-6/℃as the radius of Ln3+ increases. The present ceramics are promising candidates for high dielectric constant and low loss dielectric ceramics.
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Two compounds Ba 6 Zn 0.67 Nb 9.33 O 3 and Ba 6 Zn 0.67 Ta 9.33 O 30 with tungsten bronze structure were synthesized in the BaO-ZnO-Nb 2 O 5 /Ta 2 O 5 systems by the conventional high temperature solid-state reaction.The stru cture and dielectric properties of Ba 6 Zn 0.67 Nb 9.33 O 3 and Ba 6 Zn 0.67 Ta 9.33 O 30 were determined by X-ray powder diffraction,scanning electron microscope a nd dielectric measurements.The results show that Ba 6 Zn 0.67 Ta 9.33 O 30 belongs to paraelectric phase of fully filled tetragonal tungsten bronze str ucture at room temperature with unit cell parameters a=1.26256(4)nm, c=0.39698(2)nm.The room temperature dielectric constant( ε )of Ba 6 Zn 0.67 Ta 9.33 O 30 ceramic reached108combined with a low dielectric loss of0.005at1MHz .While Ba 6 Zn 0.67 Nb 9.33 O 3 belongs to fully filled tetragonal tungsten bronze structure at room tempera ture with the unit cell parameters a=1.25940(3)nm,c=0.40008 (2)nm.Ba 6 Zn 0.67 Nb 9.33 O 30 ceramic shows significant relaxor behaviors,and the phase transition from f erroelectric to paraelectric occurred at55℃(at1MHz).The room temperature dielectric constant( ε )of ceramic reached570at1MHz.
