以TGA-DTA为手段,考察N,N'-乙撑双硬脂酰胺(EBS)在氮气气氛中的热分解行为和分解动力学。用Flynn-Wall-Ozawa、Kissinger和?atava-?esták法计算了EBS的热分解动力学参数,并推断了分解机理。结果表明,从519.15 K到723.15 K EBS...以TGA-DTA为手段,考察N,N'-乙撑双硬脂酰胺(EBS)在氮气气氛中的热分解行为和分解动力学。用Flynn-Wall-Ozawa、Kissinger和?atava-?esták法计算了EBS的热分解动力学参数,并推断了分解机理。结果表明,从519.15 K到723.15 K EBS热分解过程分为两个阶段。两个阶段的表观活化能分别为78.41和88.38 k J×mol^(-1),指前因子分别为2.188×10~8和7.586×10~8 min^(-1),热分解机理函数的积分式分别为g(α)=1-(1-α)2和g(α)=α。为进一步开发与利用EBS提供基础数据。展开更多
Guanidinium trifluoroacetate (GTFA), a semi-organic non-linear optical material with molecular formula C3H6F3N3O2, has been synthesized at ambient temperature. Second harmonic generation (SHG) efficiency has been obse...Guanidinium trifluoroacetate (GTFA), a semi-organic non-linear optical material with molecular formula C3H6F3N3O2, has been synthesized at ambient temperature. Second harmonic generation (SHG) efficiency has been observed in this crystal though it crystallizes in centrosymmetric space group. Bulk single crystal of GTFA with a size of 22 x 7 x 2mm3 is successfully grown by submerged seed solution method. The grown crystals of GTFA have been subjected to various characterization studies such as X-ray diffraction, CHNS, FTIR analysis, UV-Vis spectrum, TGA/DTA, powder SHG test, laser damage threshold and microhardness studies.展开更多
A new semiorganic nonlinear optical crystal of bisthiourea nickel bromide (BTNB) was grown successfully by slow evaporation technique using water as solvent. The lattice parameters of the grown crystal have been deter...A new semiorganic nonlinear optical crystal of bisthiourea nickel bromide (BTNB) was grown successfully by slow evaporation technique using water as solvent. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. Vibrational spectrum is recorded to determine symmetries of molecular vibrations. Optical absorbance spectrum recorded revealed that this crystal has good transparency in the visible region. The second harmonic generation test of BTNB confirmed the nonlinear nature of the crystal. The BTNB crystal was analyzed by a differential thermal analysis and thermogravimetric analysis (DTA-TGA) to obtain its thermal stability. Vickers microhardness test done on the crystal shows that the crystal has greater physical strength.展开更多
The dihydrated potassium yttrium diphosphate, KYP2O7·2H2O, has been synthesized for the first time. Single-crystal XRD study has allowed the determination of its structure and correct formula. It crystallizes in ...The dihydrated potassium yttrium diphosphate, KYP2O7·2H2O, has been synthesized for the first time. Single-crystal XRD study has allowed the determination of its structure and correct formula. It crystallizes in the monoclinic system, space group P21/c, with the cell parameters a = 7.7069（3）, b = 10.5801（4）, c = 10.0204（5）A,β = 93.24（3）A, V= 815.76（6）A^3, Z= 4, Mr = 337.98, F（000） = 656, Dc = 2.752 g/cm^3 and/t = 8.073 mm^-1. The single-crystal structure was solved from 1856 unique reflections with the final R = 0.0365 and wR = 0.0772, refined with 119 parameters. The atomic arrangement of KYP2O7·2H2O is built by the P2O7 groups, the YO7 and the KO10 polyhedrons which are connected by corner and edge-sharing to form a three-dimensional framework. Water molecules are directly bonded to the Y and K atoms, and they are located in channels running along the a direction.展开更多
The nano ceramic Ba0.5Sr0.5Co0.2Fe0.8O3 (BSCF) powders have been synthesized by Sol-Gel process using nitrate based chemicals for SOFC applications since these powders are considered to be more promising cathode mater...The nano ceramic Ba0.5Sr0.5Co0.2Fe0.8O3 (BSCF) powders have been synthesized by Sol-Gel process using nitrate based chemicals for SOFC applications since these powders are considered to be more promising cathode materials for SOFC. Glycine was used as a chelant agent and ethylene glycol as a dispersant. The powders were calcined at 850℃/3 hr in the air using Thermolyne 47,900 furnace. These powders were characterized by employing SEM/EDS, XRD and TGA/DTA techniques. The SEM images BSCF powder indicate the presence of highly porous spherical particles with nano sizes. The XRD results shows the formation of BSCF perovskite phase at the calcination temperature of 850℃. From XRD line broadening technique, the average crystllite size of the BSCF powders were found to be around 9.15 - 11.83 nm and 13.63 - 17.47 nm for as prepared and after calcination at 850℃ respectively. The TGA plot shows that there is no weight loss after the temperature around 450℃ indicating completion of combustion.展开更多
The newly synthesized CdNa2?2C2O4?2H2O crystals having a size of 0.30 × 0.25 × 0.20 mm3 were grown by the single-diffusion reaction method in the silica gel medium at 28?C temperature. The crystalline nature...The newly synthesized CdNa2?2C2O4?2H2O crystals having a size of 0.30 × 0.25 × 0.20 mm3 were grown by the single-diffusion reaction method in the silica gel medium at 28?C temperature. The crystalline nature of crystals was determined in 20 days by 1) varying the concentrations of the feed solutions and the gel pH level, 2) changing the specific gravity of the feed solution, and 3) changing the gel aging period. The crystals were characterized by using the methods such as powder X-ray diffraction, FTIR, UV, SEM-EDAX, TGA/DTA, and micro-hardness test. The structure of as-grown crystals was determined by the powder crystal XRD patterns. FTIR & SEM-EDAX spectral analyses were used to confirm the presence of the required functional groups of as grown crystals. UV absorption spectrum, the absorption peaks at 224.64 nanometer, determined the energy gap. TGA/DTA thermo gram was used to detect the thermal stability of sodium mixed cadmium oxalate dihydrate crystals. The present grown crystals were brittle and also plastic in nature was identified by Vickers micro-hardness test.展开更多
A series of five chalcone derivatives with different substituents in para and meta posions have been synthesized, and single crystals were successfully grown in aceton solution by slow evaporation solution growth tech...A series of five chalcone derivatives with different substituents in para and meta posions have been synthesized, and single crystals were successfully grown in aceton solution by slow evaporation solution growth technique (SESGT). Single crystal X-ray studies revealed that all the crystals crystallized in noncentrosymmetric space group with their molecular dipoles perfectly aligned in a direction-favorable for large nonlinear optical effects. Kurtz powder tests revealed that all five materials have second-harmonic-generating properties with maximum efficiencies of approximately 14 times that of urea standard. UV-vis-NIR spectroscopy and thermogravimetric analyses are also presented for all of the reported materials. Among the five chalcones, high quality single crystals of 4-Methoxy-4'-chlorochalcone were grown by SESGT, and its crystalline perection were studied by using a high resolution X-ray diffractometry (HRXRD).展开更多
Most Mediterranean regions face a high risk to forest fires, estimation and anticipation of this risk modeled as a stochastic propagation process reproduces well some fire properties. This model needs information on t...Most Mediterranean regions face a high risk to forest fires, estimation and anticipation of this risk modeled as a stochastic propagation process reproduces well some fire properties. This model needs information on the behavior of the bio-physical properties of vegetation associated to combustion. An experimental study to analyze the structure of a leaf of Laurel shrub at different biological stages is presented; it allows following the structural exchanges induced on the leaf by the effect of increasing temperature. For this purpose, both dielectric and TGA （Thermogravimetric Analysis）/DTA （Differentialthermal Analysis） was performed to a better understanding of the pyrolysis phenomenon. The results obtained provide information on the process of thermal degradation caused by fire. The evolution of the leaf impedance as a function of the applied frequency characterizes the moisture loss in plant species during pyrolysis. The dielectric response confirms the proposition to the equivalent circuit of the leaf as a composite of liquid and solid parts. The TGA/DTA results detected the behaviour of the solid parts in the fire under a constant heating rate, and were able to show all the transformation subjected by the Laurel leaf until ignition and all the gases released during it.展开更多
Super plasticizer was synthesized by using coal coking by product washing oil and industrial naphthalene. The results show that sulfonationt time （2.5 h）, sulfonation temperature （160 ℃） and condensation time （5...Super plasticizer was synthesized by using coal coking by product washing oil and industrial naphthalene. The results show that sulfonationt time （2.5 h）, sulfonation temperature （160 ℃） and condensation time （5.0 h） are key factors. Adding oxidizing agent MO in the course of synthesis can decrease the emission of SO2 in exhaust （20%）. Compared with NF, NF-30 have some advantages in lower cost, high water reducing rate （19.7%） and optimum early strengths. Moreover, TGA-DTA and SEM analysis were adopted to research the NF-30 modified concrete on hydyation mechanism. The analysis show that, compared with NF, there are a large number of hydration products such as Ca （OH）2, C-S-H, AFt etc of NF-30, the structure of NF-30 is dense and the performance is good.展开更多
文摘以TGA-DTA为手段,考察N,N'-乙撑双硬脂酰胺(EBS)在氮气气氛中的热分解行为和分解动力学。用Flynn-Wall-Ozawa、Kissinger和?atava-?esták法计算了EBS的热分解动力学参数,并推断了分解机理。结果表明,从519.15 K到723.15 K EBS热分解过程分为两个阶段。两个阶段的表观活化能分别为78.41和88.38 k J×mol^(-1),指前因子分别为2.188×10~8和7.586×10~8 min^(-1),热分解机理函数的积分式分别为g(α)=1-(1-α)2和g(α)=α。为进一步开发与利用EBS提供基础数据。
文摘Guanidinium trifluoroacetate (GTFA), a semi-organic non-linear optical material with molecular formula C3H6F3N3O2, has been synthesized at ambient temperature. Second harmonic generation (SHG) efficiency has been observed in this crystal though it crystallizes in centrosymmetric space group. Bulk single crystal of GTFA with a size of 22 x 7 x 2mm3 is successfully grown by submerged seed solution method. The grown crystals of GTFA have been subjected to various characterization studies such as X-ray diffraction, CHNS, FTIR analysis, UV-Vis spectrum, TGA/DTA, powder SHG test, laser damage threshold and microhardness studies.
文摘A new semiorganic nonlinear optical crystal of bisthiourea nickel bromide (BTNB) was grown successfully by slow evaporation technique using water as solvent. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. Vibrational spectrum is recorded to determine symmetries of molecular vibrations. Optical absorbance spectrum recorded revealed that this crystal has good transparency in the visible region. The second harmonic generation test of BTNB confirmed the nonlinear nature of the crystal. The BTNB crystal was analyzed by a differential thermal analysis and thermogravimetric analysis (DTA-TGA) to obtain its thermal stability. Vickers microhardness test done on the crystal shows that the crystal has greater physical strength.
文摘The dihydrated potassium yttrium diphosphate, KYP2O7·2H2O, has been synthesized for the first time. Single-crystal XRD study has allowed the determination of its structure and correct formula. It crystallizes in the monoclinic system, space group P21/c, with the cell parameters a = 7.7069（3）, b = 10.5801（4）, c = 10.0204（5）A,β = 93.24（3）A, V= 815.76（6）A^3, Z= 4, Mr = 337.98, F（000） = 656, Dc = 2.752 g/cm^3 and/t = 8.073 mm^-1. The single-crystal structure was solved from 1856 unique reflections with the final R = 0.0365 and wR = 0.0772, refined with 119 parameters. The atomic arrangement of KYP2O7·2H2O is built by the P2O7 groups, the YO7 and the KO10 polyhedrons which are connected by corner and edge-sharing to form a three-dimensional framework. Water molecules are directly bonded to the Y and K atoms, and they are located in channels running along the a direction.
文摘The nano ceramic Ba0.5Sr0.5Co0.2Fe0.8O3 (BSCF) powders have been synthesized by Sol-Gel process using nitrate based chemicals for SOFC applications since these powders are considered to be more promising cathode materials for SOFC. Glycine was used as a chelant agent and ethylene glycol as a dispersant. The powders were calcined at 850℃/3 hr in the air using Thermolyne 47,900 furnace. These powders were characterized by employing SEM/EDS, XRD and TGA/DTA techniques. The SEM images BSCF powder indicate the presence of highly porous spherical particles with nano sizes. The XRD results shows the formation of BSCF perovskite phase at the calcination temperature of 850℃. From XRD line broadening technique, the average crystllite size of the BSCF powders were found to be around 9.15 - 11.83 nm and 13.63 - 17.47 nm for as prepared and after calcination at 850℃ respectively. The TGA plot shows that there is no weight loss after the temperature around 450℃ indicating completion of combustion.
文摘The newly synthesized CdNa2?2C2O4?2H2O crystals having a size of 0.30 × 0.25 × 0.20 mm3 were grown by the single-diffusion reaction method in the silica gel medium at 28?C temperature. The crystalline nature of crystals was determined in 20 days by 1) varying the concentrations of the feed solutions and the gel pH level, 2) changing the specific gravity of the feed solution, and 3) changing the gel aging period. The crystals were characterized by using the methods such as powder X-ray diffraction, FTIR, UV, SEM-EDAX, TGA/DTA, and micro-hardness test. The structure of as-grown crystals was determined by the powder crystal XRD patterns. FTIR & SEM-EDAX spectral analyses were used to confirm the presence of the required functional groups of as grown crystals. UV absorption spectrum, the absorption peaks at 224.64 nanometer, determined the energy gap. TGA/DTA thermo gram was used to detect the thermal stability of sodium mixed cadmium oxalate dihydrate crystals. The present grown crystals were brittle and also plastic in nature was identified by Vickers micro-hardness test.
文摘A series of five chalcone derivatives with different substituents in para and meta posions have been synthesized, and single crystals were successfully grown in aceton solution by slow evaporation solution growth technique (SESGT). Single crystal X-ray studies revealed that all the crystals crystallized in noncentrosymmetric space group with their molecular dipoles perfectly aligned in a direction-favorable for large nonlinear optical effects. Kurtz powder tests revealed that all five materials have second-harmonic-generating properties with maximum efficiencies of approximately 14 times that of urea standard. UV-vis-NIR spectroscopy and thermogravimetric analyses are also presented for all of the reported materials. Among the five chalcones, high quality single crystals of 4-Methoxy-4'-chlorochalcone were grown by SESGT, and its crystalline perection were studied by using a high resolution X-ray diffractometry (HRXRD).
文摘Most Mediterranean regions face a high risk to forest fires, estimation and anticipation of this risk modeled as a stochastic propagation process reproduces well some fire properties. This model needs information on the behavior of the bio-physical properties of vegetation associated to combustion. An experimental study to analyze the structure of a leaf of Laurel shrub at different biological stages is presented; it allows following the structural exchanges induced on the leaf by the effect of increasing temperature. For this purpose, both dielectric and TGA （Thermogravimetric Analysis）/DTA （Differentialthermal Analysis） was performed to a better understanding of the pyrolysis phenomenon. The results obtained provide information on the process of thermal degradation caused by fire. The evolution of the leaf impedance as a function of the applied frequency characterizes the moisture loss in plant species during pyrolysis. The dielectric response confirms the proposition to the equivalent circuit of the leaf as a composite of liquid and solid parts. The TGA/DTA results detected the behaviour of the solid parts in the fire under a constant heating rate, and were able to show all the transformation subjected by the Laurel leaf until ignition and all the gases released during it.
基金Funded by the National Natural Science Foundation of China(No.51175004)Educational Commission of Anhui Province of China(No.KJ2012A078)
文摘Super plasticizer was synthesized by using coal coking by product washing oil and industrial naphthalene. The results show that sulfonationt time （2.5 h）, sulfonation temperature （160 ℃） and condensation time （5.0 h） are key factors. Adding oxidizing agent MO in the course of synthesis can decrease the emission of SO2 in exhaust （20%）. Compared with NF, NF-30 have some advantages in lower cost, high water reducing rate （19.7%） and optimum early strengths. Moreover, TGA-DTA and SEM analysis were adopted to research the NF-30 modified concrete on hydyation mechanism. The analysis show that, compared with NF, there are a large number of hydration products such as Ca （OH）2, C-S-H, AFt etc of NF-30, the structure of NF-30 is dense and the performance is good.
