arXiv subjects

Eva Stepanovska

Publications and source records attributed to Eva Stepanovska.

4 recordsLinked to original sources

arXiv2026

Morphological Evolution of Nickel-Fullerene Thin Film Mixtures

Hybrid systems consisting of metal-fullerene composites exhibit intriguing properties but often suffer from thermal instability. With proper control, such instability can be harnessed to enable the formation of sophisticated nanostructures with nanometric precision. These self-organization phenomena are not limited to thermal stimulation alone but can also be triggered by other external stimuli. In this work, we investigate the morphological evolution of thin films composed of evaporated C60 and sputtered nickel mixtures, focusing on how external stimuli influence both their structural and electrical properties. Thin films were prepared under controlled deposition conditions, and their surface morphology was analyzed using advanced characterization techniques. Progressive changes in film morphology were observed as a function of composition and external treatment, highlighting the interplay between metallic and molecular components. In particular, it was observed that, due to the annealing treatment, the sample undergoes strong phase separation, with the formation of structures tens of microns in diameter and an increase in electrical resistance, exhibiting insulating behavior. These findings provide insights into the mechanisms governing hybrid thin film formation and suggest potential applications in electronic, optoelectronic, and energy-related devices.

cond-mat.mtrl-sci↗

arXiv2026

Effects of pulsed and continuous light and heavy ion irradiation on the morphology and electrical properties of Ag+C60 and Au+C60 composite thin films

Metal - organic nanocomposite thin films represent a versatile class of materials whose properties can be effectively tuned through external stimuli. In this study, Ag+C60 and Au+C60 nanocomposite thin films were briefly investigated to elucidate the effects of ion irradiation on both their morphology and electrical properties. The films were synthesized by co-deposition of noble metals and fullerenes, using ion beam sputtering of metal targets combined with simultaneous thermal evaporation of C60. The as - deposited films were characterized by ion beam analysis to determine their composition and element depth distributions. Subsequently, the samples were irradiated at room temperature with either a continuous Ar ion beam or a pulsed C ion beam, both at an energy of 20 keV and a fluence of 1 x 1015 ions/cm2. Irradiation-induced morphological changes were examined by scanning electron microscopy. While the C-irradiated films retained compact and homogeneous surface morphologies, Ar irradiation induced pronounced surface restructuring, resulting in highly corrugated and porous-like surfaces. In addition to morphology, the electrical resistance of the films was measured. The results indicate that C-irradiated samples exhibit only minor changes in resistivity, whereas Ar irradiation strongly affects the electrical properties, with the most significant impact observed for the Au+C60 system. The observed changes in electrical resistance closely correlate with the irradiation-induced surface morphology. The measurement results are briefly discussed below.

cond-mat.mtrl-sci↗

arXiv2026

NASICON solid-electrolyte modification and analysis using ion and neutron beams

Solid electrolytes (SEs) for sodium-based superionic conductors (NaSICON) are widely recognized for their excellent ionic conductivity and application in sodium based energy storage systems. While considerable effort has been made to develop thin electrolytes for all-solid-state batteries (ASSBs) for lithium ions, only a few sodium-based SEs have been successfully fabricated as thin films. These thin films are particularly desirable for their reduced electrical resistance, which typically increases with the thickness of the SE. By reducing the thickness of the SEs to the nanometer scale, their ionic conductivity can be significantly enhanced. In this study, the NASICON composite was initially prepared in the form of pellets using the mixed oxide technique with a planetary ball mill and synthesized by the solid-state method at 1250 {\deg}C. The resulting pellets were used as sputtering targets in a low-energy ion facility to prepare continuous and uniform NASICON nanofilms. To explore the effect of ion implantation on the electrical properties of NASICON, the prepared films were bombarded with Ni ions at 1.1 MeV and varying fluences, using the Tandetron accelerator at the CANAM infrastructure (NPI \v{R}e\v{z}). The electrical properties of both the synthesized and implanted films were analyzed through electrochemical impedance spectroscopy (EIS). The results, describing the impact of irradiation on NASICON's properties, are presented here.

cond-mat.mtrl-sci↗

arXiv2026

Hybrid films of Co - C60 preparation and changes induced by external stimuli

In this work, we report on the study on organic-metal hybrid systems, in particular Co-C60 fullerene thin films. This study mainly focused on the investigation of the morphological and structural evolution of the film surface after various external stimuli designed to provide energy to the system. For film growth, we adopted an innovative approach, combining ion-beam sputtering of a pure metal target with thermal evaporation of C60 in a co-deposition setup. The films underwent a series of treatments to induce modifications. Laser and ion irradiations were performed using a pulsed laser, a continuous Ar beam, and a pulsed C beam. In addition, thermal annealing in vacuum was performed to examine the long-term effects of temperature. The composition of deposited film was investigated using Ion Beam Analysis, the morphology and the structure, and the effects of treatments on the films were studied using SEM and TEM microscopies and Raman spectroscopy. Changes in electrical resistance were also measured to explore potential applications of these films after treatment.

cond-mat.mtrl-sci↗