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Praseodymium (Pr2O3) doped PbO-Ro2O3-WO3-B2O3 glasses were prepared by melt quenching method and their optical absorption and emission spectra were characterized, for three different heavy metal oxides (Ro2O3 = Sb2O3, Al2O3, and Bi2O3). The characteristics of the glass matrix are confirmed by X-ray diffraction spectra. Many structural properties can be identified by Fourier Transform infrared spectra of the glasses, such as PbO, B2O3, and WO3. From the optical absorption spectra, the absorption edges, and the values of direct and indirect band gap transitions and Urbach energies were calculated. The oscillator strengths of the absorption bands were determined by the Judd-Ofelt model, and the Judd-Ofelt intensity parameters O_2, O_4, and O_6 were calculated for each of the studied glasses. Moreover, the nephelauxetic ratio ß, bonding parameter d, and optical basicity ¿^th were also calculated to characterize the bonding nature of the Pr3+ rare-earth ions. From the emission spectra, spontaneous radiative transition probability A_t, total radiative transition probability A_T, luminance branching ratio ß_r, and radiative life time t_rad were calculated. From the spectra, the CIE color coordinates were also calculated for all the studied glasses. This research confirms that the studied materials are suitable for red laser applications., Postprint (updated version)

The influence of modifier oxides (Ro2O3 = Sb2O3, Al2O3, and Bi2O3) on the spectral analysis of PbO-Ro2O3-WO3-B2O3 glasses doped with Nd3+ ions is investigated in this work. Samples were prepared by the melt quench method, and their optical, luminescence, and physical properties were examined. From the measured properties, it is observed that the density and refractive index of the studied glasses vary non-linearly with the concentration of Nd2O3, leading to the formation of cross-linked networks under the polaraisability of the oxide glasses. The optical band gap (E_0) and Urbach energy (¿E) was determined by using UV-visible spectra; it also varies non-linearly based on the modifier oxides and the formation of non-bridging oxygen ions. The oscillator strengths of the absorption bands were determined by the Judd-Ofelt model, and the three intensity parameters O_2, O_4, and O_6 were calculated for each glass. From these parameters, the transition probability (A_t), radiative life time (t_rad), branching ratio (ß_r), quantum efficiency (¿), and non-radiative decay rate (W_NR) were calculated. From these results, it can be concluded that the studied glasses can be used for laser and optical applications., Peer Reviewed, Postprint (author's final draft)

The viscoelastic response of a novel composite (A356 aluminum alloy matrix with ceramic reinforcement particles developed from colliery shale waste) is measured with dynamic-mechanical analyzer, and is compared to pure aluminum, aluminum alloys A356, 7075 and 2024, and another composite (6061 aluminum alloy matrix reinforced with SiC particles). The studied materials show some common features but the novel composite is one of the most stable (a rapid decrease in stiffness starts only at very high temperature). Moreover, compared to the A356 alloy, the composite shows higher stiffness (since the reinforcement particles are stiffer than the A356 matrix and may foster precipitation hardening) and higher mechanical damping/internal friction (likely due to relaxations associated with the reinforcement particles and to the larger grain size for the A356 alloy). A typical relaxation peak in aluminum attributed to grain boundary sliding is suppressed in the composite because the reinforcement particles pin the grain boundaries., Peer Reviewed, Postprint (author's final draft)

The use of metal matrix composites (MMC) has increased steadily in the last two decades. Conventional MMC are usually produced by addition of either Al2O3 or SiC particles, or their combinations, into molten pure metals or alloys. However, when preparing the MMC through melting routes, there is significant loss of those costly particles, making fabrication more expensive. Lightweight MMC are important and researchers are urged to develop cheaper production techniques. In this work, the viscoelastic response of a novel aluminum metal matrix composite (AMC) is measured. The studied AMC, with A356 alloy matrix, was produced with a novel technique which allows incorporating reinforcement consisting of Al2O3, SiC and C, novel ceramic particles developed indigenously from colliery shale, avoiding the addition of costly reinforcing agents like Al2O3 or SiC in the matrix. The experimental results, obtained with a dynamic-mechanical analyzer, are compared to those for pure aluminum and commercial aluminum alloys 7075 (Al–Zn–Mg), 2024 (Al–Cu–Mg), 6061 and 6082 (Al–Mg–Si alloys). The objective of this research is to characterize the influence of the temperature, loading frequency and microstructure on the viscoelastic behavior of this novel, low-cost AMC, and to establish the interest of this AMC for applications like, for instance, damping systems, compared to the mentioned alloys., Peer Reviewed, Postprint (published version)