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This paper presents the synthesis and characterization of graphene–polymer composites, focusing on their mechanical and antibacterial properties. Graphene flakes were obtained via an electrochemical method and integrated into polyamide 6 (PA6) matrices using melt intercalation. Various characterization techniques confirmed the quality of the graphene flakes, including X-ray diffraction (XRD), Raman spectroscopy, and infrared (IR) spectroscopy, as well as scanning and transmission electron microscopy (SEM and TEM) imaging. Mechanical tests showed an increase in the elastic modulus with graphene incorporation, while the impact strength decreased. The SEM analysis highlighted the dispersion of the graphene flakes within the composites and their impact on fracture behavior. Antimicrobial tests demonstrated significant antibacterial properties of the composites, attributed to both oxidative stress and mechanical damage induced by the graphene flakes. The results suggest promising applications for graphene–polymer composites in advanced antimicrobial materials. [ABSTRACT FROM AUTHOR]

Aluminum garnets display exceptional adaptability in incorporating mismatching elements, thereby facilitating the synthesis of novel materials with tailored properties. This study explored Ce3+-doped Tb3Al5−xScxO12 crystals (where x ranges from 0.5 to 3.0), revealing a novel approach to control luminescence and photoconversion through atomic size mismatch engineering. Raman spectroscopy confirmed the coexistence of garnet and perovskite phases, with Sc substitution significantly influencing the garnet lattice and induced A1g mode softening up to Sc concentration x = 2.0. The Sc atoms controlled sub-eutectic inclusion formation, creating efficient light scattering centers and unveiling a compositional threshold for octahedral site saturation. This modulation enabled the control of energy transfer dynamics between Ce3+ and Tb3+ ions, enhancing luminescence and mitigating quenching. The Sc admixing process regulated luminous efficacy (LE), color rendering index (CRI), and correlated color temperature (CCT), with adjustments in CRI from 68 to 84 and CCT from 3545 K to 12,958 K. The Ce3+-doped Tb3Al5−xScxO12 crystal (where x = 2.0) achieved the highest LE of 114.6 lm/W and emitted light at a CCT of 4942 K, similar to daylight white. This approach enables the design and development of functional materials with tailored optical properties applicable to lighting technology, persistent phosphors, scintillators, and storage phosphors. [ABSTRACT FROM AUTHOR]

The synthesis and structural characteristics of nanocrystalline LaAlO3 perovskites doped with different concentrations of Nd3+ ions are reported. Their excitation and Stokes emission spectra, in which significant concentration quenching was observed, were recorded and characterized. The measurements of anti-Stokes laser induced white emission (LIWE) spectra were also performed. It was found that the LIWE intensity increased exponentially with the excitation laser power above the excitation threshold. In particular, the concentration and pressure dependences of the LIWE spectra of La1−xNdxAlO3 were investigated. Despite the pronounced concentration quenching observed in the Stokes emission, no such effect could be observed in the anti-Stokes one. A possible inter-valence charge transfer (IVCT) mechanism for the white emission, in which different bands that were observed correspond to different valences of Nd, is proposed. [ABSTRACT FROM AUTHOR]

In this work, Ba2MgWO6: Eu3+ (BMW: Eu3+) ceramic materials with a double perovskite structure were sintered using the High-Pressure Low-Temperature sintering (HPLT) technique. As part of the research, the influence of pressure (CP), sintering temperature (CT), and sintering time (CTS) on the structure and luminescence of the doped BMW were determined. Structural analysis via XRD and SEM + EDS and spectroscopic analysis via emission and excitation spectra, decay time, and absorption spectra of the obtained ceramics were performed. Dense double perovskite ceramics were obtained with a cubic structure with optimal sintering parameters: T = 500 °C, p = 8 GPa, and t = 1 min. The increase in temperature caused an increased extinction of the luminescence due to the diffusion of carbon into the ceramics. The increase in pressure led to the formation of the amorphous phase, which increased the speed of non-radiative transitions and also led to the extinction of the luminescence. The increase in sintering time from 1 to 3 min enhanced the luminescence output, but when the ceramic was sintered for 5 min, the luminescence was quenched, most likely by increasing the rate of the non-radiative process, as evidenced by reduced decay time. [ABSTRACT FROM AUTHOR]

In the presented work, the tellurite glasses TeO2-WO3-ZnO doped with Tm3+ and Ho3+ ions were prepared by the same glass forming method. X-ray diffraction (XRD) and differential thermal analysis (DTA) techniques were used to study the effects of the forming technology on the thermal and structural properties of the fabricated glasses. After controlled crystallization of investigated glasses, the emission in the VIS- and NIR range was determined. The effect of silver doping on emission intensity was investigated. The value of the activation energy of the glass crystallization process was determined, while the Ea value for pure TeO2 glass was much lower than for tellurite glasses TeO2-WO3-ZnO. [ABSTRACT FROM AUTHOR]