The microstructural study was conducted on cement and cement-slag pastes immersed in different concentrations of Mg（NO3）2 solutions utilizing ^29Si, ^27Al NMR spectroscopy and XRD techniques. The results show that t...The microstructural study was conducted on cement and cement-slag pastes immersed in different concentrations of Mg（NO3）2 solutions utilizing ^29Si, ^27Al NMR spectroscopy and XRD techniques. The results show that the hydration of both the cement and cement-slag pastes is delayed when the pastes are cured in Mg（NO3）2 solutions as compared to the pastes cured in water. Moreover, Mg^2＋ ions also exhibit an decalcifying and dealuminizing effect on the C-A-S-H in cement and cement-slag pastes, and thereby decrease Ca/Si and Al[4]/Si ratios of the C-A-S-H. The dealuminization of C-A-S-H is mitigated for cement-slag paste as compared to pure cement paste. The depolymerized calcium and aluminum ions from C-A-S-H gel mainly enter the pore solution to maintain the pH value and form Al^[6] in TAH, respectively. On the other hand, Mg^2＋ ions exert an impact on the intra-transition between Al^[6] species, from AFm and hydrogarnet to hydrotalcite-like phase. NO3^-ions are interstratified in the layered Mg-Al structure and formed nitrated hydrotalcite-like phase（Mg1-xAlx（OH）2（NO3）x·nH2O）. Results from both ^27Al NMR and XRD data show that ettringite seems not to react with Mg^2＋ ions.展开更多
12 natural alkali feldspars have been studied by(29)~Si and(27)~Al MAS NMR as well as XRD,IR,EPMA and chemical analysis.Three kinds of(29)~Si NMR spectra,i.e.the spectra of microcline,perthiteand perthite with minor p...12 natural alkali feldspars have been studied by(29)~Si and(27)~Al MAS NMR as well as XRD,IR,EPMA and chemical analysis.Three kinds of(29)~Si NMR spectra,i.e.the spectra of microcline,perthiteand perthite with minor plagioclase,have been obtained.There are two types of(27)~Al NMR spectra.The(27)~Alspectrum of microcline is the same as that of perthite,but is different from the spectrum for perthite contain-ing plagioclase.Through this study,we found that the results of NMR and IR are inconsistent with that ofXRD,which shows that the transition of alkali feldspar from monoclinic to triclinic system might be a rathercomplicated process.展开更多
Calcium-Silicate-Hydrate-phases (CSH-phases) are important binding agents of building materials. The synthesis of CSH phases and their structural characterization was done to investigate the crystallization in depende...Calcium-Silicate-Hydrate-phases (CSH-phases) are important binding agents of building materials. The synthesis of CSH phases and their structural characterization was done to investigate the crystallization in dependence of an increasing CaO/SiO2 ratio (C/S ratios) from 0.41 up to 1.66 at temperatures in the crossover region of tobermorite to xonotlite (180℃ and 230℃). Parallel runs with the same C/S ratio but on the one hand with constant mass of quartz and variation of lime and on the other hand under reverse conditions (constant mass of lime but variable amounts of quartz) were performed at both temperatures. The aim was to clarify the connections of crystallization mechanism and kinetics of phase formation with structure, crystallinity and morphology of the CSH’s in the mentioned C/S ratio for both temperatures in the tobermorite-xonotlite crossover region. The parallel experiments with different mass ratios of the educts are important to study the influence of time evaluation of supersaturation within the solution under the peculiarities of the retrograde solubility of lime but accelerated solubility of quartz. The products were characterized by XRD, SEM/EDX, FTIR and 29Si MAS NMR spectroscopy (using the Q-site nomenclature [1]). The experiments could clarify some important connections of crystallization process and the reaction pathway.展开更多
采用水热合成法,以二正丙胺(DPA)和二异丙胺(DIPA)混合物为模板剂合成SAPO-11分子筛,考察了模板剂用量和混合模板剂中DPA和DIPA配比对所得产物的影响,并通过XRD、N2吸附、NH3-TPD和29Si MAS NMR等手段对样品进行了表征。结果表明,改变...采用水热合成法,以二正丙胺(DPA)和二异丙胺(DIPA)混合物为模板剂合成SAPO-11分子筛,考察了模板剂用量和混合模板剂中DPA和DIPA配比对所得产物的影响,并通过XRD、N2吸附、NH3-TPD和29Si MAS NMR等手段对样品进行了表征。结果表明,改变模板剂用量和配比不仅可以调节SAPO-11结晶度,还会改变Si在分子筛骨架上的分布,从而调节SAPO-11的酸性。当模板剂用量比为1.5,模板剂中DPA的质量分数为66%时,样品的Si区面积最小,Si(nAl)(0<n<4)结构最多。因此,分子筛酸性和对正十四烷异构活性也最高。展开更多
文摘以含氟的二胺5,5’-(六氟异丙基)-二-(2-氨基苯酚)(6FHP)及二酐4, 4’-(六氟异丙基)-苯二酸酐(6FDA)或均苯四甲酸酐(PMDA)为单体,以分散红 1(DR1)为活性生色分子合成具有非线性光学特性的含氟聚酰亚胺,并采用溶胶-凝胶(Sol-Gel)法合成相应的聚酰亚胺／SiO2杂化材料．采用固态29 Si MAS NMR谱研究了含氟聚酰亚胺／SiO2杂化材料的交联结构,结果表明杂化材料中是以T3、Q3、Q4结构为主,说明在杂化材料中形成了交联网状结构．采用衰减全反射(ATR)测定了聚酰亚胺和杂化材料在832 nm处的电光系数,其值分别为 32、28、34和29 pm／V,结果表明具有较高的电光系数．
基金Funded by National Natural Science Foundation of China(Nos.51778513,51402003,51578004)China Ministry of Science and Technology(No.2015CB655101)
文摘The microstructural study was conducted on cement and cement-slag pastes immersed in different concentrations of Mg（NO3）2 solutions utilizing ^29Si, ^27Al NMR spectroscopy and XRD techniques. The results show that the hydration of both the cement and cement-slag pastes is delayed when the pastes are cured in Mg（NO3）2 solutions as compared to the pastes cured in water. Moreover, Mg^2＋ ions also exhibit an decalcifying and dealuminizing effect on the C-A-S-H in cement and cement-slag pastes, and thereby decrease Ca/Si and Al[4]/Si ratios of the C-A-S-H. The dealuminization of C-A-S-H is mitigated for cement-slag paste as compared to pure cement paste. The depolymerized calcium and aluminum ions from C-A-S-H gel mainly enter the pore solution to maintain the pH value and form Al^[6] in TAH, respectively. On the other hand, Mg^2＋ ions exert an impact on the intra-transition between Al^[6] species, from AFm and hydrogarnet to hydrotalcite-like phase. NO3^-ions are interstratified in the layered Mg-Al structure and formed nitrated hydrotalcite-like phase（Mg1-xAlx（OH）2（NO3）x·nH2O）. Results from both ^27Al NMR and XRD data show that ettringite seems not to react with Mg^2＋ ions.
文摘12 natural alkali feldspars have been studied by(29)~Si and(27)~Al MAS NMR as well as XRD,IR,EPMA and chemical analysis.Three kinds of(29)~Si NMR spectra,i.e.the spectra of microcline,perthiteand perthite with minor plagioclase,have been obtained.There are two types of(27)~Al NMR spectra.The(27)~Alspectrum of microcline is the same as that of perthite,but is different from the spectrum for perthite contain-ing plagioclase.Through this study,we found that the results of NMR and IR are inconsistent with that ofXRD,which shows that the transition of alkali feldspar from monoclinic to triclinic system might be a rathercomplicated process.
文摘Calcium-Silicate-Hydrate-phases (CSH-phases) are important binding agents of building materials. The synthesis of CSH phases and their structural characterization was done to investigate the crystallization in dependence of an increasing CaO/SiO2 ratio (C/S ratios) from 0.41 up to 1.66 at temperatures in the crossover region of tobermorite to xonotlite (180℃ and 230℃). Parallel runs with the same C/S ratio but on the one hand with constant mass of quartz and variation of lime and on the other hand under reverse conditions (constant mass of lime but variable amounts of quartz) were performed at both temperatures. The aim was to clarify the connections of crystallization mechanism and kinetics of phase formation with structure, crystallinity and morphology of the CSH’s in the mentioned C/S ratio for both temperatures in the tobermorite-xonotlite crossover region. The parallel experiments with different mass ratios of the educts are important to study the influence of time evaluation of supersaturation within the solution under the peculiarities of the retrograde solubility of lime but accelerated solubility of quartz. The products were characterized by XRD, SEM/EDX, FTIR and 29Si MAS NMR spectroscopy (using the Q-site nomenclature [1]). The experiments could clarify some important connections of crystallization process and the reaction pathway.
文摘采用水热合成法,以二正丙胺(DPA)和二异丙胺(DIPA)混合物为模板剂合成SAPO-11分子筛,考察了模板剂用量和混合模板剂中DPA和DIPA配比对所得产物的影响,并通过XRD、N2吸附、NH3-TPD和29Si MAS NMR等手段对样品进行了表征。结果表明,改变模板剂用量和配比不仅可以调节SAPO-11结晶度,还会改变Si在分子筛骨架上的分布,从而调节SAPO-11的酸性。当模板剂用量比为1.5,模板剂中DPA的质量分数为66%时,样品的Si区面积最小,Si(nAl)(0<n<4)结构最多。因此,分子筛酸性和对正十四烷异构活性也最高。
