Multifunctional AsS/FeO nanocomposites prepared by high-energy mechanical milling are probed by complementary methods of positron annihilation lifetime (PAL) spectroscopy, supported by microstructure characterization using X-ray powder diffraction (XRPD) with analysis applied to the first sharp diffraction peak (FSDP), morphology studies by transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS) and high-resolution TEM (HRTEM). These nanocomposites are shown to consist of FeO crystallites with particle sizes of 8–21 nm, and far-separated β-AsS crystallites surrounded by amorphous As-S phase. In respect to PAL data, the effect of milling is identified as possible conversion from Ps traps to positron-trapping sites depending on preferential chemistry of atomic surrounding. So, the interfacial triple junctions at the intersections of FeO crystallites are identified as principal positron traps in AsS/FeO nanocomposites with competitive influence from free-volume defects of amorphous As-S phase.

This work was supported by the Slovak Research and Development Agency under the contract no. APVV-14-0103 and Slovak Grant Agency VEGA (project 2/0027/14). YaSh is grateful to SAIA, supporting this research within National Scholarship Program of the Slovak Republic. European Union through the CT-2011-1-REGPOT285895 AL-NANOFUN project (Advanced Laboratory for the Nano-Analysis of novel Functional materials), for the microscopy facilities sited in Seville is also gratefully acknowledged.