Nanoporous characterization of modified humidity-sensitive MgO-Al2O3 ceramics by positron annihilation lifetime spectroscopy method

Functional Materials and Nanotechnologies 2018

Klym, H.^1 ; Ingram, A.^2 ; Hadzaman, I.^3 ; Karbovnyk, I.^4 ; Vasylchyshyn, I.^1 ; Popov, A.I.^5

Lviv Polytechnic National University, 12 Bandera St., Lviv

79646, Ukraine^1

Opole University of Technology, 75 Ozimska St., Opole

45370, Poland^2

Drohobych Ivan Franko State Pedagogical University, 24 I. Franko St., Drohobych

82100, Ukraine^3

Ivan Franko National University of Lviv, 107 Tarnavskogo St., Lviv

79017, Ukraine^4

Institute of Solid State Physics, University of Latvia, 8 Kengaraga St., Riga

LV- 1063, Latvia^5

关键词: Al2O3 ceramics;    Fitting procedure;    Humidity sensitive;    ortho-Positronium lifetime;    Positron annihilation lifetime spectroscopy;    Positron annihilation lifetime spectrum;    Positronium trapping;    Third component;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/503/1/012019/pdf
DOI  :  10.1088/1757-899X/503/1/012019

来源: IOP

【 摘 要 】

Investigation of nanopores in the humidity-sensitive MgO-Al2O3 ceramics modified at 1100°C for 2 hours was performed using positron annihilation lifetime spectroscopy method. Lifetimes of the third and fourth components of positron annihilation lifetime spectra obtained by four-component fitting procedure were used for calculation of nanopores radii. Transformation in free volumes was studied in ceramics after drying and exposure to water vapor. It is established that the lifetime of the third component decreases and the intensity of this component increases in ceramics exposed to water vapor reflecting ortho-positronium decay in nanopores simultaneously with annihilation in water bubbles. The characteristics of the fourth component (lifetime and intensity) decrease in ceramics exposed to water vapor reflecting ortho-positronium trapping in free-water volume of nanopores. Final drying of the MgO-Al2O3 ceramics results in returning of ortho-positronium lifetimes and intensities to the initial values confirming good desorption of water from nanopores of ceramics.