Sn(OH)4 was prepared by the conventional solution precipitate method,followed by supercritical CO2 drying.The resultant Sn(OH)4 was divided into three aliquots and calcined at 400,600 and 800 °C,respectively,...Sn(OH)4 was prepared by the conventional solution precipitate method,followed by supercritical CO2 drying.The resultant Sn(OH)4 was divided into three aliquots and calcined at 400,600 and 800 °C,respectively,thus SnO2 nanoparticles with average crystallite sizes of 5,10 and 25 nm were obtained.Furthermore,three SnO2 thick film gas sensors(denoted as sensors S-400,S-600 and S-800) were fabricated from the above SnO2 nanoparticles.The adhesion of sensing materials on the surface of alumina tube is good.Compared to the sensors S-600 and S-800,sensor S-400 showed a much higher sensitivity to 1000 μL/L ethanol.On the other hand,sensor S-800 showed a much lower intrinsic resistance and improved selectivity to ethanol than sensors S-400 and S-600.X-Ray diffraction(XRD),transmission electron microscopy(TEM) and selective area electron diffraction(SAED) measurements were used to characterize the SnO2 nanoparticles calcined at different temperatures.The differences in the gas sensing performance of these sensors were analyzed on the basis of scanning electron microscopy(SEM).展开更多
Al2O3 porous nanosolid was prepared via solvothermal hot-press(SHP) method.The dielectric constant of Al2O3 porous nanosolid is as low as 2.34,while its compressive strength is very poor.In order to improve the comp...Al2O3 porous nanosolid was prepared via solvothermal hot-press(SHP) method.The dielectric constant of Al2O3 porous nanosolid is as low as 2.34,while its compressive strength is very poor.In order to improve the compressive strength and maitain low dielectric constant,polyimide was introduced to prepare Al2O3 /polyimide composite porous nanosolid.Compared to Al2O3 porous nanosolid,Al2O3 /polyimide composite porous nanosolid possesses much higher compressive strength,which reaches its saturation value when the mass loading of polyimide is 7.75%.In addition,the in situ Fourier transformation infrared(FTIR) monitoring result reveals that Al2O3 /polyimide composite porous nanosolid is stable up to 400 °C.展开更多
By means of the in-situ Fourier transformation infrared spectroscopy(FTIR), the properties of BBr3/ benzene solution, which is usually used as the reactant and solution to synthesize BN by benzene-thermal method, ha...By means of the in-situ Fourier transformation infrared spectroscopy(FTIR), the properties of BBr3/ benzene solution, which is usually used as the reactant and solution to synthesize BN by benzene-thermal method, have been investigated. The results show that there are some side reactions between BBr3 and benzene: (1) BBr3 as an electron-deficient molecule reacts with benzene at room temperature; (2) below 100℃, substitution of Br atom for H atom of benzene(ring-H) dominates in BBr3/benzene solution; (3) cracking of benzene ring occurs at a temperature above 100℃; (4) decomposition of benzene molecules and formation of long-chain aliphatic compounds feature the spectra of BBr3/benzene solution collected at above 160℃, They are unfavor for BN to form when BBr3 is excessive in the synthesis of BN by benzene-thermal route. On the basis of the experimental results, a coordination reaction mechanism via a η^2-C6H6 binding mode in BBr3/benzene solution is suggested.展开更多
A multi-step reaction route was developed to synthesize boron nitride(BN) nanoparticles via the reactionbetween NaN3 and BC13 in a benzene-thermal solution. By means of this route, the crystallinity of BN nanopartic...A multi-step reaction route was developed to synthesize boron nitride(BN) nanoparticles via the reactionbetween NaN3 and BC13 in a benzene-thermal solution. By means of this route, the crystallinity of BN nanoparticleswas improved via increasing the reaction steps. Meanwhile, a phase transformation from hexagonal BN(hBN) or tur-bostratic BN(tBN) to cubic BN(cBN) occurred, resulting in the increase of cBN content. Moreover, the content ofcBN also slightly increased when the temperature was elevated from 265 ℃ to 280 ℃.展开更多
Effect of pressure on thermal behavior of KDP crystals is investigated by using the in-situ infrared reflective spectra.Compared with that under normal atmosphere,the onset temperature of decomposition under pressure ...Effect of pressure on thermal behavior of KDP crystals is investigated by using the in-situ infrared reflective spectra.Compared with that under normal atmosphere,the onset temperature of decomposition under pressure of 1 MPa is improved to from 210℃to 213℃,suggesting that the thermal stability of KDP is enhanced.Under pressure of 2 MPa,the thermal stability is deteriorated and KDP begins to decompose at 183℃.Under normal atmosphere KDP decomposes in route of translating to K_(4)P_(2)O_(7)firstly,and then to KPO_(3).Under pressures of 1 MPa and 2MPa,KDP translates to KPO_(3)directly without any other polymeric intermediates.展开更多
GaP nanocrystals were synthesized by both the organic solvent reflux and high temperature high pressure benzene thermal synthesis methods.The effect of organic solvent on the optical absorption properties of GaP nanoc...GaP nanocrystals were synthesized by both the organic solvent reflux and high temperature high pressure benzene thermal synthesis methods.The effect of organic solvent on the optical absorption properties of GaP nanocrystals were studied.The results show that crystal grains of the sample synthesized by the latter method have better quality and uniformity.The solvents which consist of polar molecules and form strong chemical bonds with Ga atoms cause obvious redshift of the absorption spectra of GaP nanocrystals.The absorption spectra redshift much more if the solvent molecules have π electrons which involved in the formation of complex bond between Ga atoms and solvent molecules.展开更多
基金Supported by the National Natural Science Foundation of China(No.60906008)the Foundation for Excellent Middle-aged or Young Scientists from Shandong Province of China(No.BS2010CL007)
文摘Sn(OH)4 was prepared by the conventional solution precipitate method,followed by supercritical CO2 drying.The resultant Sn(OH)4 was divided into three aliquots and calcined at 400,600 and 800 °C,respectively,thus SnO2 nanoparticles with average crystallite sizes of 5,10 and 25 nm were obtained.Furthermore,three SnO2 thick film gas sensors(denoted as sensors S-400,S-600 and S-800) were fabricated from the above SnO2 nanoparticles.The adhesion of sensing materials on the surface of alumina tube is good.Compared to the sensors S-600 and S-800,sensor S-400 showed a much higher sensitivity to 1000 μL/L ethanol.On the other hand,sensor S-800 showed a much lower intrinsic resistance and improved selectivity to ethanol than sensors S-400 and S-600.X-Ray diffraction(XRD),transmission electron microscopy(TEM) and selective area electron diffraction(SAED) measurements were used to characterize the SnO2 nanoparticles calcined at different temperatures.The differences in the gas sensing performance of these sensors were analyzed on the basis of scanning electron microscopy(SEM).
基金Supported by the National Natural Science Foundation of China(Nos.50990061,51021062,21073107 and 51102151)the Postdoctoral Science Foundation of China(No.20100481245)+1 种基金the Natural Science Foundation(No.ZR2011EMQ002)the Postdoctoral Innovation Foundation(No.201003077) of shandong Province, China
文摘Al2O3 porous nanosolid was prepared via solvothermal hot-press(SHP) method.The dielectric constant of Al2O3 porous nanosolid is as low as 2.34,while its compressive strength is very poor.In order to improve the compressive strength and maitain low dielectric constant,polyimide was introduced to prepare Al2O3 /polyimide composite porous nanosolid.Compared to Al2O3 porous nanosolid,Al2O3 /polyimide composite porous nanosolid possesses much higher compressive strength,which reaches its saturation value when the mass loading of polyimide is 7.75%.In addition,the in situ Fourier transformation infrared(FTIR) monitoring result reveals that Al2O3 /polyimide composite porous nanosolid is stable up to 400 °C.
基金Supported by the National Natural Science Foundation of China(No.50672048)the Program of Shandong Science & Technology Council,China(No.2006GG2202039)
文摘By means of the in-situ Fourier transformation infrared spectroscopy(FTIR), the properties of BBr3/ benzene solution, which is usually used as the reactant and solution to synthesize BN by benzene-thermal method, have been investigated. The results show that there are some side reactions between BBr3 and benzene: (1) BBr3 as an electron-deficient molecule reacts with benzene at room temperature; (2) below 100℃, substitution of Br atom for H atom of benzene(ring-H) dominates in BBr3/benzene solution; (3) cracking of benzene ring occurs at a temperature above 100℃; (4) decomposition of benzene molecules and formation of long-chain aliphatic compounds feature the spectra of BBr3/benzene solution collected at above 160℃, They are unfavor for BN to form when BBr3 is excessive in the synthesis of BN by benzene-thermal route. On the basis of the experimental results, a coordination reaction mechanism via a η^2-C6H6 binding mode in BBr3/benzene solution is suggested.
基金Supported by the National Natural Science Foundation of China(Nos.21073107,51102151 and 50990061)the Natural Science Foundation of Shandong Province,China(No.2R2011EMQ002)+1 种基金the Independent Innovation Foundation(No.2010TS039)the Postdoctoral Foundation of Shandong University,China
文摘A multi-step reaction route was developed to synthesize boron nitride(BN) nanoparticles via the reactionbetween NaN3 and BC13 in a benzene-thermal solution. By means of this route, the crystallinity of BN nanoparticleswas improved via increasing the reaction steps. Meanwhile, a phase transformation from hexagonal BN(hBN) or tur-bostratic BN(tBN) to cubic BN(cBN) occurred, resulting in the increase of cBN content. Moreover, the content ofcBN also slightly increased when the temperature was elevated from 265 ℃ to 280 ℃.
基金Supported by the National Natural Science Foundation of China under Grant Nos 50721002 and 50990061.
文摘Effect of pressure on thermal behavior of KDP crystals is investigated by using the in-situ infrared reflective spectra.Compared with that under normal atmosphere,the onset temperature of decomposition under pressure of 1 MPa is improved to from 210℃to 213℃,suggesting that the thermal stability of KDP is enhanced.Under pressure of 2 MPa,the thermal stability is deteriorated and KDP begins to decompose at 183℃.Under normal atmosphere KDP decomposes in route of translating to K_(4)P_(2)O_(7)firstly,and then to KPO_(3).Under pressures of 1 MPa and 2MPa,KDP translates to KPO_(3)directly without any other polymeric intermediates.
文摘GaP nanocrystals were synthesized by both the organic solvent reflux and high temperature high pressure benzene thermal synthesis methods.The effect of organic solvent on the optical absorption properties of GaP nanocrystals were studied.The results show that crystal grains of the sample synthesized by the latter method have better quality and uniformity.The solvents which consist of polar molecules and form strong chemical bonds with Ga atoms cause obvious redshift of the absorption spectra of GaP nanocrystals.The absorption spectra redshift much more if the solvent molecules have π electrons which involved in the formation of complex bond between Ga atoms and solvent molecules.