Optical properties investigation and multicolor behavior of neodymium (Nd3+)-doped oxyfluoride silicate glasses SiO2-PbO-PbF2.

The aim of this research is to investigate novel compositions of oxyfluoride glasses doped with Neodymium (Nd3+) rare earth ions in the visible spectrum. This area has not been extensively studied in the existing literature, so it is vital to understand the favorable photoluminescence characteristics within this part of the electromagnetic spectrum. Therefore, we synthesized and characterized SiO2-PbO-PbF2 (SPF) doped with 1% neodymium (Nd3+) ions glasses. Spectroscopic analyses, based on Judd-Ofelt theory, were conducted on absorption spectra. These analyses enabled to determine absorption cross-sections, transition probabilities, and Judd-Ofelt intensity parameters Ω2, Ω4, and Ω6 for the different transition. Additionally, we calculated various radiative properties, such as branching ratios, integrated cross-sections, radiative lifetimes, emission cross-section, optical gain, and the multicolor behavior (chromaticity coordinates, CIE diagram) under different excitation wavelengths. The results suggest promising prospects for using these oxyfluoride silicate glasses doped with Nd3+ as a fluorophore, potentially for lasing materials around 630-nm emission and in other photonic applications.

Investigation of the Critical Behavior, Magnetocaloric Effect and Hyperfine Structure in the Fe72Nb8B20 Powders.

Microstructure as well as magnetic, thermal and magnetocaloric properties of the mechanically alloyed Fe72Nb8B20 powders have been investigated by means of Mössbauer spectrometry, differential scanning calorimetry (DSC), and magnetic measurements. The Mössbauer spectrometry results showed the formation of nanostructured Fe(B) and Fe(Nb) solid solutions, Fe2B boride, and an amorphous phase. The endothermic and exothermic peaks that are observed in the DSC curves might be related to the Curie temperature, and the crystallization of the amorphous phase, respectively. The critical exponent values around the magnetic phase transition of the amorphous phase (TC = 480 K), are deduced from the modified Arrott plots, Kouvel-Fisher curves and critical isotherm examination. The calculated values (ß = 0.457 ± 0.012, γ = 0.863 ± 0.136 and δ = 3.090 ± 0.004) are near to those of the mean field model, revealing a dominating role of magnetic order arising due to long-range ferromagnetic interactions, as the critical exponents are mean-field-like. The maximum entropy change and the refrigerant capacity values are 1.45 J/kg·K and 239 J/kg, respectively, under a magnetic field of 5 T.

Physical Investigations of (Co, Mn) Co-Doped ZnO Nanocrystalline Films.

Undoped as well as (Co, Mn) co-doped Zinc oxides have been effectively developed on glass substrates, taking advantage of the spray pyrolysis procedure. The X-ray diffraction XRD as well as X-ray photoelectron spectroscopy (XPS) measurements have recognized a pure hexagonal wurtzite form of ZnO, and no other collateral phases such as MnO2 or CoO2 have been observed as a result of doping. The calculated values of the texture coefficient (TC) were between 0.15 and 5.14, indicating a dominant orientation along the (002) plane. The crystallite size (D) varies with the (Co, Mn) contents. The dislocation density (δ) as well as the residual microstrains increased after Co and Mn doping. Furthermore, the surface morphology of the films has been affected significantly by the Co and Mn incorporation, as shown by the scanning electron microscopy (SEM) investigation. The study of the optical properties exhibits a red shift of the band gap energy (Eg) with the (Co, Mn) co-doping. The magnetic measurements have shown that the undoped and (Co, Mn) co-doped ZnO thin films displayed room-temperature ferromagnetism (RTFM).