Klym Halyna, Karbovnyk Ivan, Piskunov Sergei, Popov Anatoli I
Specialized Computer Systems Department, Lviv Polytechnic National University, 12 Bandera Str., 79013 Lviv, Ukraine.
Department of Electronics and Computer Technologies, Ivan Franko National University of Lviv, 50 Dragomanov Str., 79005 Lviv, Ukraine.
Nanomaterials (Basel). 2021 Dec 13;11(12):3373. doi: 10.3390/nano11123373.
Herein we demonstrate the specifics of using the positron annihilation lifetime spectroscopy (PALS) method for the study of free volume changes in functional ceramic materials. Choosing technological modification of nanostructured MgAlO spinel as an example, we show that for ceramics with well-developed porosity positron annihilation is revealed through two channels: positron trapping channel and ortho-positronium decay. Positron trapping in free-volume defects is described by the second component of spectra and ortho-positronium decay process by single or multiple components, depending on how well porosity is developed and on the experimental configuration. When using proposed positron annihilation lifetime spectroscopy approaches, three components are the most suitable fit in the case of MgAlO ceramics. In the analysis of the second component, it is shown that technological modification (increasing sintering temperature) leads to volume shrinking and decreases the number of defect-related voids. This process is also accompanied by the decrease of the size of nanopores (described by the third component), while the overall number of nanopores is not affected. The approach to the analysis of positron annihilation lifetime spectra presented here can be applied to a wide range of functional nanomaterials with pronounced porosity.
在此，我们展示了使用正电子湮没寿命谱（PALS）方法研究功能陶瓷材料中自由体积变化的具体情况。以纳米结构MgAlO尖晶石的工艺改性为例，我们表明，对于具有发达孔隙率的陶瓷，正电子湮没通过两个通道揭示：正电子捕获通道和正电子素衰变。自由体积缺陷中的正电子捕获由光谱的第二个分量描述，正电子素衰变过程由单个或多个分量描述，这取决于孔隙率的发达程度和实验配置。在使用所提出的正电子湮没寿命谱方法时，对于MgAlO陶瓷，三个分量是最合适的拟合。在分析第二个分量时，表明工艺改性（提高烧结温度）导致体积收缩并减少与缺陷相关的空隙数量。这个过程还伴随着纳米孔尺寸的减小（由第三个分量描述），而纳米孔的总数不受影响。本文提出的正电子湮没寿命谱分析方法可应用于广泛的具有明显孔隙率的功能纳米材料。
