N-type Si-based type-Ⅰ clathrates with different Ga content were synthesized by combining the solid-state reaction method,melting method and spark plasma sintering （SPS） *** effects of Ga composition on high temper...
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N-type Si-based type-Ⅰ clathrates with different Ga content were synthesized by combining the solid-state reaction method,melting method and spark plasma sintering （SPS） *** effects of Ga composition on high temperature thermoelectric transport properties were *** results show that at room temperature,the carrier concentration decreases, while the carrier mobility increases slightly with increasing Ga *** Seebeck coefficient increases with increasing Ga content. Among all the samples,Ba7.93Ga17.13Si28.72exhibits higher Seebeck coefficient than the others and reaches -135μV·K^-1 at 1000 *** sample prepared by this method exhibits very high electrical conductivity,and reaches 1.95x 10^5 S·m^-1 for Ba8.01Ga16.61Si28.93 at room *** thermal conductivity of all samples is almost temperature independent in the temperature range of 300-1000 K,indicating the behaviour of a typical *** maximum ZT value of 0.75 is obtained at 1000 K for the compound Ba7.93Ga17.13Si28.72.
Calcia stabilized zirconia（CSZ） ceramics were prepared with 7wt% calcia-stabilized zirconia powder by pressureless sintering technology. The crystal phases of the sintered samples were studied by X-ray diffraction（...
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Calcia stabilized zirconia（CSZ） ceramics were prepared with 7wt% calcia-stabilized zirconia powder by pressureless sintering technology. The crystal phases of the sintered samples were studied by X-ray diffraction（XRD） and Raman spectroscopy techniques, and the microstructures of the fracture surfaces were observed by scanning electron spectroscopy（SEM）. The phase compositions and the lattice parameters of cubic calcia-stabilized zirconia were calculated by XRD patterns. As the sintering temperature increasing from 1400℃ to 1600℃, the monoclinic zirconia content decreases gradually, finally all monoclinic phase transforms to cubic calcia-stabilized zirconia, which is deter- mined to be Ca0.134Zr0.866O1.866. It is revealed that monoclinic zirconia is the main factor causing minute cracks on the surface of sintered samples, and the combination of the XRD patterns and Raman spectra is an effective way to research the phase transformations of zirconia.
A stainless steel/10wt%TiC nanocomposite particles were prepared by high-energy ball-milling method using stainless steel, carbon and titanium as raw materials. The evolution of phase composition, microstructure and s...
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A stainless steel/10wt%TiC nanocomposite particles were prepared by high-energy ball-milling method using stainless steel, carbon and titanium as raw materials. The evolution of phase composition, microstructure and specific surface area of the stainless steel/TiC nanocomposite particles with increasing ball-milling time in the range of 0-100 h were investigated by XRD, SEM, TEM and BET techniques. The results showed that the stainless steel/TiC nano-composite particles were fabricated when the ball-milling time was longer than 20 h. However, the nanocomposite particles were soldered and agglomerated again when the ball-milling time was longer than 60 h. The microstructure of the composite particles transformed from lamellar structure to nanostructure during the repeated process of the cold welding and cracking. TEM image reveals clearly that the in-situ TiC nanoparticles with grain size of 3-8 nm are in the interior of the stainless steel/TiC nanocomposite particles obtained by ball-milling 100 h.
ad-free piezoelectric ceramics of a(Bi0.5Na0.5)TiO3-b(Bi0.5K0.5)TiO3-cBaTiO3 (BNBK) ternary system near the composition of MPB has been widely investigated in recent decades.
ad-free piezoelectric ceramics of a(Bi0.5Na0.5)TiO3-b(Bi0.5K0.5)TiO3-cBaTiO3 (BNBK) ternary system near the composition of MPB has been widely investigated in recent decades.
A series of new polyamides 3a-d containing aryl-azo, ether and sulfone groups in the main chain were synthesized from bis[4-（4-aminophenoxy）phenyl sulfone] 1 and several azo aromatic diacyl chlorides 2a-d by the low...
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A series of new polyamides 3a-d containing aryl-azo, ether and sulfone groups in the main chain were synthesized from bis[4-（4-aminophenoxy）phenyl sulfone] 1 and several azo aromatic diacyl chlorides 2a-d by the low temperature solution polycondensation technique. FTIR spectroscopy, nuclear magnetic resonance （NMR） and elemental analyses confirmed the structure of these polymers. Owing to the aryl and amide groups in the main chain, these polymers exhibit photochromic properties as well as excellent thermal stabilities. The transition temperatures （Tg） are between 242 and 265℃, and the char yields at 800 ℃ in nitrogen atmosphere were above 39%. Based on incorporation of flexible ether linkages and polar sulfone groups, the polyamides show desirable solubility in organic solvents such as DMAc, N,N-dimethylformamide （DMF）, N-methyl-2-pyrroidinone （NMP） and dimethylsulfoxide （DMSO）. And it is exemplified that polyamide containing 2 and 2＇ substitutes performed better solubility.
Flame-retardant mechanism of magnesium oxychloride （M OC） in EP was in-vestigated by limiting oxygen index （LOI）, XRD, SEM, TG-DTG and DSC. The results show that MOC performed well as an inorganic flame-retardant ...
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Flame-retardant mechanism of magnesium oxychloride （M OC） in EP was in-vestigated by limiting oxygen index （LOI）, XRD, SEM, TG-DTG and DSC. The results show that MOC performed well as an inorganic flame-retardant in EP. When the content of MOC is 50%, the LOI of EP reaches 29.6% and mass of residual char reaches 9.6%. The flame retarde mechanism of MOC is due to the synergies of diluting, cooling, catalyzing char forming and obstructing effects.
Silver powder was fabricated by spray pyrolysis, using 2%-20% AgNO3 solution, 336-500 mL/h flux of AgNO3 solution, 0.28-0.32 MPa flux of carrier gas and in the 620-820 ℃ temperature range. The effects of furnace set ...
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Silver powder was fabricated by spray pyrolysis, using 2%-20% AgNO3 solution, 336-500 mL/h flux of AgNO3 solution, 0.28-0.32 MPa flux of carrier gas and in the 620-820 ℃ temperature range. The effects of furnace set temperature, concentration of AgNO3 aqueous solution, flux of AgNO3 aqueous solution as well as carrier gas on the morphology and particle size distribution of silver powder, were investigated. The experimental results showed that with the high concentration of AgNO3 aqueous solution, the average grain size of silver decreased with the increasing of furnace set temperature. But the gain size distribution was not homogenous, the discontinuous grain growth occurred. With the low concentration of AgNO3 aqueous solution, the higher furnace set temperature made the nano sliver grains sintered together to grow. Nano silver powder about 100 nm was fabricated by spray pyrolysis, using 2wt% AgNO3 solutions, 336 mL/h flux of AgNO3 aqueous solution, 0.32 MPa flux of carrier gas at 720 ℃ furnace set temperature.
The spherical agglomerated particles were fabricated by spray drying with the powders of NiO, Cr2O3 and TiO2. Plasma spray power, which has good property of flowability, was acquired by heat treatment from the particl...
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The spherical agglomerated particles were fabricated by spray drying with the powders of NiO, Cr2O3 and TiO2. Plasma spray power, which has good property of flowability, was acquired by heat treatment from the particles at 1200℃ in the reducing atmosphere. Dark and uniform coating of More than 50 μm thick was deposited on the copper sheet substrate by plasma spraying. It is found that the infrared normal total emissivity of the coating is up to 0.91 at 600℃ by infrared radiation testing. The X-ray diffraction analysis shows that the formation of （Cr0.88Ti0.12）2O3 and spinel structural NiCr2O4 in the coating is the main reason for high efficient infrared radiation, and the phase structure and performance of coating is favorable under the thermal cycle between room temperature and 600℃.
A steady nano organic-inorganic perovskite hybrid with [H(2)3-AMP](3/2)Fe(CN)(6) (3-AMP = 3-methylaminopyridine) was prepared in the air. The structure is an unusual layered organic-inorganic type. The resulting hybri...
A steady nano organic-inorganic perovskite hybrid with [H(2)3-AMP](3/2)Fe(CN)(6) (3-AMP = 3-methylaminopyridine) was prepared in the air. The structure is an unusual layered organic-inorganic type. The resulting hybrid enveloped in paraffin to prepare [H(2)3-AMP](3/2)Fe(CN)(6) paste electrode (HPE) shows good electrochemical activity and a couple of oxidation and reduction peaks with potential of cyclic voltammometry (CV) at around 440 mV and 30 mV. Compared with that on CPE, oxidation potential of Fe(CN)(6) (3-) on HPE shifts negatively 259.7 mV and that of reduction shifts positively 338.7 mV, which exhibits that [H(2)3-AMP](3/2)Fe(CN)(6) can accelerate the electron-transfer to improve the electrochemical reaction reversibility. Such characteristics of [H(2)3-AMP](3/2)Fe(CN)(6) have been employed to prepare the DNA biosensor. The single-strand DNA (ssDNA) and double-strand DNA (dsDNA) immobilized on HPE, respectively, can improve the square wave voltammometry (SWV) current and SWV potential shifts positively. The effect of pH was evaluated. And there is hybridization peak on SWV curve using HPE immobilized ssDNA in the complementary ssDNA solution. And HPE immobilized ssDNA can be utilized to monitor the DNA hybridization and detect complementary ssDNA, covering range from 3.24 x 10(-7) to 6.72 x 10(-5) g/mL with detection limit of 1.57 x 10(-7) g/mL. The DNA biosensor exhibits a good stability and reproducibility.
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