YBa2Cu3O7-x （YBCO） films with embedded BaZrO3 and BaTiO3 nanoparticles were fabricated by metalorganic deposition using trifluoroacetates （TFA-MOD）. Both X-ray diffraction and transmission electron microscopy reve...YBa2Cu3O7-x （YBCO） films with embedded BaZrO3 and BaTiO3 nanoparticles were fabricated by metalorganic deposition using trifluoroacetates （TFA-MOD）. Both X-ray diffraction and transmission electron microscopy revealed that these BaZrO3 and BaTiO3 nanoparticles had random orientations and were distributed stochastically in the YBCO matrix. The unique combined microstructure enhances the critical current density （Jc） of the BaZrO3/BaTiO3 doped-YBCO films, while keeping the critical transition temperature （Tc） close to that in the pure YBCO films. These results indicate that BaZrO3 and BaTiO3 nanoparticles provide strong flux pinning in YBCO films.展开更多
YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure...YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure,degree of texture and critical properties of the films were evaluated.In order to understand the combined effects of the humidity and the calcining and firing temperatures on critical properties,heat-treatment was performed at various temperatures with the other processing variables fixed.The films were calcined at 400-430 ℃ and fired at 750-800 ℃ in a 0-12.1% humidified Ar-O2 atmosphere.The texture was determined by pole-figure analysis.The amount of the BaF2 phase was effectively reduced and a sharp and strong biaxial texture was formed under a humidified atmosphere,which led to increased critical properties.In addition,the microstructure varied significantly with firing temperature but changed little with calcining temperature.The highest IC of 40 A/cm-width,which corresponds to JC value of 1.8 MA/cm2,was obtained for the films fired at 775 ℃(in 12.1% humidity) after calcining at 400-430 ℃.It is likely that the highest IC value is due to the formation of a more pure YBCO phase,c-axis grains,and a denser microstructure.展开更多
YBa2Cu3O7-x（YBCO） films with co-doping BaTiO3（BTO） and Y2O3 nanostructures were prepared by metal organic deposition using trifluoroacetates（TFA-MOD）. The properties of the BTO/Y2O3co-doped YBCO films with diffe...YBa2Cu3O7-x（YBCO） films with co-doping BaTiO3（BTO） and Y2O3 nanostructures were prepared by metal organic deposition using trifluoroacetates（TFA-MOD）. The properties of the BTO/Y2O3co-doped YBCO films with different excess yttrium have been systematically studied by x-ray diffraction（XRD）, Raman spectra, and scanning electron microscope（SEM）. The optimized content of yttrium excess in the BTO/Y2O3co-doped YBCO films is 10 mol.%, and the critical current density is as high as - 17 mA/cm^2（self-field, 65 K） by the magnetic signal. In addition, the Y2Cu2O5 was formed when the content of yttrium excess increases to 24 mol.%, which may result in the deterioration of the superconducting properties and the microstructure. The unique combination of the different types of nanostructures of BTO and Y2O3 in the doped YBCO films, compared with the pure YBCO films and BTO doped YBCO films, enhances the critical current density（JC） not only at the self-magnetic field, but also in the applied magnetic field.展开更多
There is a generally accepted conclusion that trifluoroacetic acid (TFA) does occur naturally, in part based on the large quantities of TFA in the oceans (61 - 205 million tonnes, measured in 1998-2002). However, the ...There is a generally accepted conclusion that trifluoroacetic acid (TFA) does occur naturally, in part based on the large quantities of TFA in the oceans (61 - 205 million tonnes, measured in 1998-2002). However, the recent review paper “Insufficient evidence for the existence of natural trifluoroacetic acid” concludes that “the presence of TFA in the deep ocean and lack of closed TFA budget is not sufficient evidence that TFA occurs naturally, especially without a reasonable mechanism of formation”. Industrial sources of TFA can only result from the use of fluoride minerals in industrial processes. Major industrial uses of fluorspar started significant expansion from about the same time (1930s). Over 190 million tonnes of fluorspar have been mined in the period 1930 to 1999. An inventory has been developed (1930-1999), accounting for most of the fluorspar production (86%) and estimating emissions of TFA. Industrial emissions of TFA are estimated as 230,000 to 470,000 tonnes. Significant other industrial uses of fluorides have not been identified that could account for the large burden of TFA in the oceans. This inventory provides complementary evidence that the quantity of TFA in the oceans must include a large natural burden.展开更多
The neodymium trifluoroacetate complexes were synthesized and characterized by single-crystal X-ray diffraction for [Nd（CF3COO）3·Bpy·（H2O）3]Bpy（1）,elemental and TG analysis,FT-IR spectra,and PL spectra...The neodymium trifluoroacetate complexes were synthesized and characterized by single-crystal X-ray diffraction for [Nd（CF3COO）3·Bpy·（H2O）3]Bpy（1）,elemental and TG analysis,FT-IR spectra,and PL spectra for Nd（CF3COO）3·Bpy（2）（Bpy：2,2＇-bipyri-dine）.The most interesting feature of the crystal structure for 1 is that it comprises a coordinated 2,2＇-bipyridine molecule and an out-sphere 2,2＇-bipyridine molecule.At the same time,the C-O distances appeared average which indicates the three atoms of carboxylato forming elec-tron-conjugate system.Hydrogen bond and π-π-stacking link the binuclear to two-dimensional sheet.The optical spectra for 2 exhibited that the complex possessed typical Nd（III） ion absorption and photoluminescence emission.The emission cross-section of 4F3/2→4I11/2 fluores-cence transition（3.63×10-20 cm2） was comparable with some laser glasses,which indicated good radiative properties of this neodymium trifluoroacetate complex in liquid matrix.The thermal analysis indicated that it was quite stable to heat.展开更多
建立了离子色谱-间接紫外检测法同时分析离子液体中的三氟乙酸根（CF3COO-）、四氟硼酸根（BF4-）和三氟甲烷磺酸根（CF3SO3-）的方法。用Shodex IC NI-424阴离子交换柱作为分离柱,探讨了影响上述三种离子保留和检测的因素及其保留规律...建立了离子色谱-间接紫外检测法同时分析离子液体中的三氟乙酸根（CF3COO-）、四氟硼酸根（BF4-）和三氟甲烷磺酸根（CF3SO3-）的方法。用Shodex IC NI-424阴离子交换柱作为分离柱,探讨了影响上述三种离子保留和检测的因素及其保留规律。最终选用色谱条件为：以1.75 mmol·L^-1邻苯二甲酸-1.68 mmol·L^-1三（羟甲基）氨基甲烷为淋洗液,柱温45℃,流速1.0 m L·min^-1,UV检测波长设定在265 nm。在此条件下,可实现上述三种阴离子的同时分析,且色谱峰形良好。所测阴离子的检出限（S/N=3）为0.39-1.57 mg·L^-1,保留时间和峰面积的相对标准偏差（n=5）均在1%以下。将此方法应用于测定离子液体中的三氟乙酸根、四氟硼酸根及三氟甲烷磺酸根,加标回收率为99%-102%。该方法简单、准确、可靠,具有较好的实用性。展开更多
Iodomethane is usually used as an electrophilic methylation reagent.Herein,we report its use as a C1 organocatalyst for the aerobic ortho-selective trifluoromethylation of pyridines in the absence of a transition meta...Iodomethane is usually used as an electrophilic methylation reagent.Herein,we report its use as a C1 organocatalyst for the aerobic ortho-selective trifluoromethylation of pyridines in the absence of a transition metal.Trifluoroacetic acid(TFA)was employed as an inexpensive,readily available trifluoromethyl source.The reaction efficiently produced a variety of trifluoromethylation products,with good functional group compatibility.Pyridine-containing drug molecules could also be selectively trifluoromethylated for late-stage functionalizations.Mechanistic studies showed that iodomethane selectively reacted with the pyridine starting material,rather than the pyridine product,to generate the corresponding N-methylpyridinium iodide.The decarboxylation of trifluoroacetic acid produced a trifluoromethyl anion,which added to the methylpyridinium iodide,and the subsequent aerobic rearomatization led to the generation of the ortho-trifluoromethylated product.展开更多
We report the first trifluoroacetic anhydride- and trifluoroacetic acid-promoted cascade reaction with phtoroglucinoltribenzyl ether and carboxylic acid as starting materials. By simply varying the temperature of syst...We report the first trifluoroacetic anhydride- and trifluoroacetic acid-promoted cascade reaction with phtoroglucinoltribenzyl ether and carboxylic acid as starting materials. By simply varying the temperature of systems containing the same starting materials, different products were produced in high yields. A three-step consecutive reaction process was also proposed.展开更多
A new scolopendra-type polymer of polydodecyloxybenzoyl[1,5]-diazocine（PDBD） was designed and prepared using 2,5-bis（4-（dodecyloxy）-benzoyl）terephthaloyl azide with trifluoroacetic acid（TFA） via one-pot reacti...A new scolopendra-type polymer of polydodecyloxybenzoyl[1,5]-diazocine（PDBD） was designed and prepared using 2,5-bis（4-（dodecyloxy）-benzoyl）terephthaloyl azide with trifluoroacetic acid（TFA） via one-pot reaction in good yields. The structure of polymer was characterized using ~1 H-NMR, ^（13） C-NMR and MALDI-TOF spectra. The polymer PDBD exhibits good thermal stability as measured by TGA and DSC, and can be dissolved well in common organic solvents such as chloroform and tetrahydrofuran. In addition, UV-Vis spectral studies indicate that the polymer PDBD shows unique optical property changes（protonation/deprotonation） in the different trifluoroacetic acid environments. The new polymer is expected to be utilized as an optical functional material for fabricating optical sensors in environmental and biological fields.展开更多
Single-layer YBa2Cu3O7-δ（YBCO） films with the thickness of over 600 nm were fabricated by modified metal organic deposition using trifluoroacetate metal organic deposition（TFA-MOD） method on LaAlO3（LAO） substra...Single-layer YBa2Cu3O7-δ（YBCO） films with the thickness of over 600 nm were fabricated by modified metal organic deposition using trifluoroacetate metal organic deposition（TFA-MOD） method on LaAlO3（LAO） substrates. Polyvinylbutyral（PVB） was added into the precursor solution to enhance the thickness of the single layer. The pyrolysis process was shortened to about 3 h due to the reduction of the fluorine content in the precursor solution.The effects of heating rate during the crystallization process on the microstructure and Jcvalues of YBCO films were investigated. The α-axis-oriented YBCO crystals dominate when the heating rate is lower than 20 °C·min^-1, while faster heating rate of 43 °C·min^-1 results in pure c-axis epitaxial growth. The Jcvalues of YBCO films increase linearly with heating rate increasing due to the increase of c-axis YBCO growth, and the critical current（Ic） value of 100 A·cm^-1 within a single-layer YBCO film is achieved.展开更多
In the presence of copper （I） halide as catalyst, a variety of carbonyl compounds could be trifluoromethylated with sodium trifluoroacetate to give the corresponding alcohols in moderate to high yields.
基金the National Natural Science Foundation of China(Grant Nos.51002149 and 51272250)the National Basic Research Program of China(Grant No.2011CBA00105)
文摘YBa2Cu3O7-x （YBCO） films with embedded BaZrO3 and BaTiO3 nanoparticles were fabricated by metalorganic deposition using trifluoroacetates （TFA-MOD）. Both X-ray diffraction and transmission electron microscopy revealed that these BaZrO3 and BaTiO3 nanoparticles had random orientations and were distributed stochastically in the YBCO matrix. The unique combined microstructure enhances the critical current density （Jc） of the BaZrO3/BaTiO3 doped-YBCO films, while keeping the critical transition temperature （Tc） close to that in the pure YBCO films. These results indicate that BaZrO3 and BaTiO3 nanoparticles provide strong flux pinning in YBCO films.
基金supported by Samsung Research Fund,Sungkyunkwan University,2006
文摘YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure,degree of texture and critical properties of the films were evaluated.In order to understand the combined effects of the humidity and the calcining and firing temperatures on critical properties,heat-treatment was performed at various temperatures with the other processing variables fixed.The films were calcined at 400-430 ℃ and fired at 750-800 ℃ in a 0-12.1% humidified Ar-O2 atmosphere.The texture was determined by pole-figure analysis.The amount of the BaF2 phase was effectively reduced and a sharp and strong biaxial texture was formed under a humidified atmosphere,which led to increased critical properties.In addition,the microstructure varied significantly with firing temperature but changed little with calcining temperature.The highest IC of 40 A/cm-width,which corresponds to JC value of 1.8 MA/cm2,was obtained for the films fired at 775 ℃(in 12.1% humidity) after calcining at 400-430 ℃.It is likely that the highest IC value is due to the formation of a more pure YBCO phase,c-axis grains,and a denser microstructure.
基金Project supported by the National Natural Science Foundation of China(Grant No.51272250)the National Basic Research Program of China(Grant No.2011CBA00105)+1 种基金the National High Technology Research and Development Program of China(Grant No.2014AA032702)the Natural Science Foundation of Beijing,China(Grant No.2152035)
文摘YBa2Cu3O7-x（YBCO） films with co-doping BaTiO3（BTO） and Y2O3 nanostructures were prepared by metal organic deposition using trifluoroacetates（TFA-MOD）. The properties of the BTO/Y2O3co-doped YBCO films with different excess yttrium have been systematically studied by x-ray diffraction（XRD）, Raman spectra, and scanning electron microscope（SEM）. The optimized content of yttrium excess in the BTO/Y2O3co-doped YBCO films is 10 mol.%, and the critical current density is as high as - 17 mA/cm^2（self-field, 65 K） by the magnetic signal. In addition, the Y2Cu2O5 was formed when the content of yttrium excess increases to 24 mol.%, which may result in the deterioration of the superconducting properties and the microstructure. The unique combination of the different types of nanostructures of BTO and Y2O3 in the doped YBCO films, compared with the pure YBCO films and BTO doped YBCO films, enhances the critical current density（JC） not only at the self-magnetic field, but also in the applied magnetic field.
文摘There is a generally accepted conclusion that trifluoroacetic acid (TFA) does occur naturally, in part based on the large quantities of TFA in the oceans (61 - 205 million tonnes, measured in 1998-2002). However, the recent review paper “Insufficient evidence for the existence of natural trifluoroacetic acid” concludes that “the presence of TFA in the deep ocean and lack of closed TFA budget is not sufficient evidence that TFA occurs naturally, especially without a reasonable mechanism of formation”. Industrial sources of TFA can only result from the use of fluoride minerals in industrial processes. Major industrial uses of fluorspar started significant expansion from about the same time (1930s). Over 190 million tonnes of fluorspar have been mined in the period 1930 to 1999. An inventory has been developed (1930-1999), accounting for most of the fluorspar production (86%) and estimating emissions of TFA. Industrial emissions of TFA are estimated as 230,000 to 470,000 tonnes. Significant other industrial uses of fluorides have not been identified that could account for the large burden of TFA in the oceans. This inventory provides complementary evidence that the quantity of TFA in the oceans must include a large natural burden.
基金supported by the National Natural Science Foundation of China(60977023,10876009)CAS Special Grant for Postgraduate Research,Innovation and Practice
文摘The neodymium trifluoroacetate complexes were synthesized and characterized by single-crystal X-ray diffraction for [Nd（CF3COO）3·Bpy·（H2O）3]Bpy（1）,elemental and TG analysis,FT-IR spectra,and PL spectra for Nd（CF3COO）3·Bpy（2）（Bpy：2,2＇-bipyri-dine）.The most interesting feature of the crystal structure for 1 is that it comprises a coordinated 2,2＇-bipyridine molecule and an out-sphere 2,2＇-bipyridine molecule.At the same time,the C-O distances appeared average which indicates the three atoms of carboxylato forming elec-tron-conjugate system.Hydrogen bond and π-π-stacking link the binuclear to two-dimensional sheet.The optical spectra for 2 exhibited that the complex possessed typical Nd（III） ion absorption and photoluminescence emission.The emission cross-section of 4F3/2→4I11/2 fluores-cence transition（3.63×10-20 cm2） was comparable with some laser glasses,which indicated good radiative properties of this neodymium trifluoroacetate complex in liquid matrix.The thermal analysis indicated that it was quite stable to heat.
文摘建立了离子色谱-间接紫外检测法同时分析离子液体中的三氟乙酸根（CF3COO-）、四氟硼酸根（BF4-）和三氟甲烷磺酸根（CF3SO3-）的方法。用Shodex IC NI-424阴离子交换柱作为分离柱,探讨了影响上述三种离子保留和检测的因素及其保留规律。最终选用色谱条件为：以1.75 mmol·L^-1邻苯二甲酸-1.68 mmol·L^-1三（羟甲基）氨基甲烷为淋洗液,柱温45℃,流速1.0 m L·min^-1,UV检测波长设定在265 nm。在此条件下,可实现上述三种阴离子的同时分析,且色谱峰形良好。所测阴离子的检出限（S/N=3）为0.39-1.57 mg·L^-1,保留时间和峰面积的相对标准偏差（n=5）均在1%以下。将此方法应用于测定离子液体中的三氟乙酸根、四氟硼酸根及三氟甲烷磺酸根,加标回收率为99%-102%。该方法简单、准确、可靠,具有较好的实用性。
基金supported by the National Natural Science Foundation of China(21971093)the Fundamental Research Funds for the Central Universities(lzujbky-2021-sp53)+1 种基金the International Joint Research Centre for Green Catalysis and Synthesis(2016B01017)the 111 Project。
文摘Iodomethane is usually used as an electrophilic methylation reagent.Herein,we report its use as a C1 organocatalyst for the aerobic ortho-selective trifluoromethylation of pyridines in the absence of a transition metal.Trifluoroacetic acid(TFA)was employed as an inexpensive,readily available trifluoromethyl source.The reaction efficiently produced a variety of trifluoromethylation products,with good functional group compatibility.Pyridine-containing drug molecules could also be selectively trifluoromethylated for late-stage functionalizations.Mechanistic studies showed that iodomethane selectively reacted with the pyridine starting material,rather than the pyridine product,to generate the corresponding N-methylpyridinium iodide.The decarboxylation of trifluoroacetic acid produced a trifluoromethyl anion,which added to the methylpyridinium iodide,and the subsequent aerobic rearomatization led to the generation of the ortho-trifluoromethylated product.
基金Supported by the National Natural Science Foundation of China（No.51209024）.
文摘We report the first trifluoroacetic anhydride- and trifluoroacetic acid-promoted cascade reaction with phtoroglucinoltribenzyl ether and carboxylic acid as starting materials. By simply varying the temperature of systems containing the same starting materials, different products were produced in high yields. A three-step consecutive reaction process was also proposed.
基金financially supported by the National Natural Science Foundation of China(No.21404066)the Qingdao Independent Innovation Found(No.15-9-1-16-jch)
文摘A new scolopendra-type polymer of polydodecyloxybenzoyl[1,5]-diazocine（PDBD） was designed and prepared using 2,5-bis（4-（dodecyloxy）-benzoyl）terephthaloyl azide with trifluoroacetic acid（TFA） via one-pot reaction in good yields. The structure of polymer was characterized using ~1 H-NMR, ^（13） C-NMR and MALDI-TOF spectra. The polymer PDBD exhibits good thermal stability as measured by TGA and DSC, and can be dissolved well in common organic solvents such as chloroform and tetrahydrofuran. In addition, UV-Vis spectral studies indicate that the polymer PDBD shows unique optical property changes（protonation/deprotonation） in the different trifluoroacetic acid environments. The new polymer is expected to be utilized as an optical functional material for fabricating optical sensors in environmental and biological fields.
基金financially supported by the National Natural Science Foundation of China (No.51002024)the Sichuan Youth Science and Technology Innovation Research Team (No.2011JTD0006)+1 种基金the Program for Cooperation of Industry, Education and Academy of Guangdong Province, China (No. 2012B091100298)the Fundamental Research Funds for the Central Universities (Nos.ZYGX2012J039, ZYGX2011Z002, and ZYGX2012J035)
文摘Single-layer YBa2Cu3O7-δ（YBCO） films with the thickness of over 600 nm were fabricated by modified metal organic deposition using trifluoroacetate metal organic deposition（TFA-MOD） method on LaAlO3（LAO） substrates. Polyvinylbutyral（PVB） was added into the precursor solution to enhance the thickness of the single layer. The pyrolysis process was shortened to about 3 h due to the reduction of the fluorine content in the precursor solution.The effects of heating rate during the crystallization process on the microstructure and Jcvalues of YBCO films were investigated. The α-axis-oriented YBCO crystals dominate when the heating rate is lower than 20 °C·min^-1, while faster heating rate of 43 °C·min^-1 results in pure c-axis epitaxial growth. The Jcvalues of YBCO films increase linearly with heating rate increasing due to the increase of c-axis YBCO growth, and the critical current（Ic） value of 100 A·cm^-1 within a single-layer YBCO film is achieved.
文摘In the presence of copper （I） halide as catalyst, a variety of carbonyl compounds could be trifluoromethylated with sodium trifluoroacetate to give the corresponding alcohols in moderate to high yields.
