arXiv subjects

Jan Bárta

Publications and source records attributed to Jan Bárta.

3 recordsLinked to original sources

arXiv2025

Composition-Dependent Properties of $\mathrm{Ce_{x}La_{0.95-x}Tb_{0.05}F_{3}}$ Nanopowders Tailored for X-Ray Photodynamic Therapy and Cathodoluminescence Imaging

This study investigates the synthesis and luminescence behavior of $\mathrm{Ce_{x}La_{0.95-x}Tb_{0.05}F_{3}}$ nanoparticles with varying $\mathrm{Ce^{3+}}$ content. The materials were prepared via a wet chemical route and thermally annealed to improve crystallinity and reduce defects. Phase composition and structural parameters were examined by X-ray diffraction (XRD), while elemental composition was determined by X-ray fluorescence (XRF). Cathodoluminescence (CL) intensity mapping was used to evaluate emission uniformity and monitor the degradation of luminescence under electron beam exposure. Photoluminescence (PL) and radioluminescence (RL) spectroscopy confirmed energy transfer from $\mathrm{Ce^{3+}}$ to $\mathrm{Tb^{3+}}$ ions. Luminescence intensities were found to depend strongly on both Ce content and thermal treatment. The results contribute to the understanding of defect-related quenching mechanisms and are relevant for the design of rare-earth-based luminescent nanomaterials for biomedical applications.

cond-mat.mtrl-sci↗

arXiv2025

Drastic reduction of the slow scintillation component in highly luminescent Ce3+ and Mg2+ doped Lu2.5Gd0.5Ga2Al3O12 garnet powders

This paper deals with the photochemical preparation of nanomaterials with garnet structure. Ce3+ and Mg2+ doped Lu2.5Gd0.5Ga2Al3O12 powders were prepared by using UV irradiation of aqueous solutions with low-pressure mercury lamps and subsequent calcination of the solid products. The synthesis was optimized and gives access to a range of doping which is very hard to achieve with single crystal growth from melt. The effect of Ce and Mg concentration on the structural and luminescence properties was studied. Garnets were analyzed using X-ray fluorescence (XRF) and X-ray powder diffraction (XRPD) and their luminescence properties under optical and X-ray photon excitations were investigated. XRF and XRD show that the samples are sufficiently chemically pure and phase-pure and their elemental composition corresponds with expectations. Laser-induced breakdown spectroscopy confirmed that Mg concentrations in Mg-codoped samples are slightly lower than the nominal. Luminescence spectra show typical emission maxima of 5d-4f Ce3+ transition and 4f-4f Gd3+ transition. The effects of the concentration of Ce3+ and Mg2+ on the RL intensity, light yields and decays were observed.

cond-mat.mtrl-sci↗

arXiv2025

Is GGAG:Ce@SiO$_2$-RB composite a prospective material for X-ray induced photodynamic therapy?

Nanocomposite material ($\mathrm{GGAG:Ce^{3+}@SiO_2-RB}$) for potential use in X-ray induced photodynamic therapy (X-PDT) was developed, thoroughly characterized, and evaluated. It consists of a scintillating $\mathrm{Gd_3(Ga_{1-x}Al_x)_5O_{12}:Ce^{3+}}$ core encapsulated in silica layer and functionalized with the photosensitizer Rose Bengal (RB). Radioluminescence measurements confirmed the energy transfer from the scintillating core to Rose Bengal. Dark toxicity and radiosensitisation effects were evaluated using Saccharomyces cerevisiae as a model organism. The nanocomposite showed minimal dark toxicity at concentrations of up to 10 mg/mL. However, X-ray irradiation experiments did not demonstrate significant singlet oxygen production compared to the controls. Although the nanocomposite design shows potential, further optimization is needed to achieve an effective X-PDT performance.

physics.med-ph↗