Positron-Annihilation-Lifetime-Spectroscopy (PALS) for the characterization of bimodal silica-gel synthesized by pseudomorphic transformation
Positron-Annihilation-Lifetime-Spectroscopy (PALS) for the characterization of bimodal silica-gel synthesized by pseudomorphic transformation
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正电子湮灭寿命光谱 (PALS) 用于表征假晶变换合成的双峰硅胶
DOI：
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发表时间：
2016
影响因子：
2.6
通讯作者：
D. Enke
中科院分区：
文献类型：
--
作者：
Hans Uhlig;Gamal Adouane;Christie Bluhm;Steve Zieger;R. Krause;D. Enke
本研究比较了氮吸附法和正电子湮灭寿命谱法（PALS）对双峰硅胶样品的表征结果。采用介孔硅胶的假晶转化法制备了双峰硅胶样品。采用不同体积的0.07 M十六烷基三甲基氢氧化铵（5-42 ml/g）制备了8个样品，得到了由原始硅胶形成的15 nm孔和由MCM-41相形成的4 nm孔的比例可控的双峰孔系统。目的是证明是否有可能直接从PALS实验中确定孔隙体积。PALS测量结果清楚地显示了材料的双峰孔隙结构。两个单独的孔隙系统可以检测到良好的分辨率。可以计算信号的峰面积，并与氮吸附测定的孔隙体积进行比较。结果表明，氮吸附测定的孔隙体积与PALS计算的峰面积之间存在一定的相关性。起始材料的测量孔隙体积之间的一些差异可以表明在起始材料中和经过伪晶转变过程后形成了封闭孔隙。PALS测量可以在微孔和中孔范围内对孔隙系统进行互补表征。双峰结构多孔材料可以被研究，单个孔隙系统分离良好。观察到的PALS强度（分别为峰面积）与不同孔隙类型的孔隙体积之间的相关性，可以通过校准和潜在封闭孔隙度的量化来直接估计PALS的孔隙体积。
In this study the results of the characterization of bimodal silica-gel samples with nitrogen adsorption and Positron-Annihilation-Lifetime-Spectroscopy (PALS) are compared. The bimodal silica-gel samples were synthesized by pseudomorphic transformation of a mesoporous silica gel. A set of eight samples was generated using different volumes of 0.07 M cetyltrimethylammonium hydroxide (5–42 ml/g) to obtain bimodal pore systems with controlled proportions of 15 nm pores of the original silica-gel and 4 nm pores formed by the MCM-41 phase. The aim was to proof if it is possible to determine the pore volumes directly from the PALS experiment. The results of the PALS measurements clearly indicate the bimodal pore structure in the materials. Two individual pore systems can be detected with a good resolution. The peak area of the signals can be calculated and compared with the pore volumes determined by nitrogen adsorption. The results show a correlation between the pore volume determined by nitrogen adsorption and the peak area calculated from PALS. Some differences between the measured pore volumes of the starting material can be an indication for the formation of a closed porosity in the starting material and after the processes of pseudomorphic transformation. The PALS measurements enable a complementary characterisation of pore systems in the micro- and mesopore range. Bimodal structured porous materials can be studied and the individual pore systems are well separated. The observed correlation between intensities (respectively peak areas) from PALS and pore volumes determined by nitrogen adsorption for the different pore classes allows the direct estimation of the pore volumes by PALS via calibration and the quantification of a potential closed porosity.
DOI：
10.1016/j.colsurfa.2012.12.024
发表时间：
2013-11-20
影响因子：
5.2
作者：
Einicke, W. -D.;Uhlig, H.;Ebbinghaus, S. G.
通讯作者：
Ebbinghaus, S. G.