Abstract: The utilization of porous biomedical implants featuring a bimodal microstructure has garnered substantial interest within the scientific community. This study delves into the intricate interplay between processing parameters, microstructural attributes, and the tribo-mechanical performance of titanium grade 4, showcasing its potential to serve as implants to address compromised cortical bone tissue. The investigation meticulously examines the impact of milling duration (10 and 20 h), proportion of milled powder (50 and 75 wt%), and the volume fraction of space-holding agents (40-60 vol% NaCl) on the resulting characteristics of the bimodal microstructure, which plays a crucial role in achieving optimal biomechanical equilibrium. The Vickers microhardness, conventional and instrumented (P-h curves), and the wear behavior (ball-on disk) are discussed in terms of bimodal microstructure distribution, particle size and porosity level inherent to the fabrication conditions (mechanical milling + space-holder + hot-pressing). In general terms, milling time and milled powder fraction were the most influent parameters on the final properties of the materials. With the processing route used, the achieved microhardness values and wear behavior are comparable with those obtained by means of surface modifications or alloys. The Young's moduli obtained were in the range of 30-50 GPa, which could help to reduce the shielding phenomenon, while presenting a good mechanical resistance and wear behavior. In light of these findings, the fabricated specimen, composed of 75 wt% milled powder subjected to a 10-h milling duration, supplemented by a 60 vol% fraction of NaCl, emerges as a prime candidate manifesting superior biomechanical equilibrium. This judicious configuration exhibits a promising trajectory for its application in bone replacement endeavors.

Abstract: La0.8Sr0.2MnO3 (LSM) perovskite as oxygen electrode material for the reversible solid oxide fuel cells (ReSOFC) was synthesized by the fast solution combustion method and assessed for subsequent calcination influence. The microstructural, morphological, compositional and optical properties of the obtained material were analyzed with X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM) coupled with an energy-dispersive X-ray spectroscopy detector (EDS) and UV-visible spectroscopy techniques. The XRD results showed the coexistence of rhombohedral R-3c and Pm-3m polymorphs for the perovskite phase, with a decreased fraction of the cubic phase as the temperature and/or time used for the calcination were increased. The HR-TEM images confirmed the existence of the R-3c and Pm-3m polymorphs for the sample subjected to calcination at 1300 degrees C, showing that the rapid combustion method did not allow the pure formation of the La0.8Sr0.2MnO3 phase for the calcination temperatures below 1400 degrees C, due to the swiftness of the combustion synthesis 500 degrees C for 5 min. The average grain size was found to be increased with the calcination time. The EDS analysis depicted a better agreement in stoichiometry with the theoretical composition. The apparent porosity was decreased with the increase in the temperature and calcination time due to the coalescence of the sintering pores. The sample obtained after the calcination at 1400 degrees C for 8 h exhibited 1.6% of porosity. The hardness was improved with the higher calcination time and temperature and reached a maximum value of 5.7 GPa that merely matched the bulk density. A similar trend was observed in the temperature dependence resistivity studies and all the samples presented a low resistivity of similar to 1.2 Omega cm in the temperature range of 600-700 degrees C. The optical characterization exhibited a broad absorption in 560-660 nm.

Abstract: In this work, we prepared La1 – xSrxGa1-yMgyO3 (LSGM) by the fast combustion method and assessed the electrical properties with respect to the composition and sintering temperature (1200, 1300, and 1400 degrees C by 6 h) as an electrolyte material for the reversible solid oxide cells (ReSOCs). For the preparation of samples, two different fuels, such as tartaric acid (TA) and citric acid (CA), with corresponding nitrate salts as precursors, were adopted for the fast combustion method (at 500 degrees C for 10 min). From the X-ray diffractograms, two main phases corresponding to LSGM orthorhombic (space group Imma) and LSGM-cubic (space group Pm-3 m) were identified. From the literature, both structures are reported as high oxygen ion conductive species, but normally they are not reported to appear together. Additionally, in some cases, an isolating (secondary) phase of LaSrGaO4 in a low concentration < 1.98% was observed. The scanning electron microscopy (SEM) studies on samples sintered at 1200 and 1300 degrees C revealed the smaller grain size and irregular morphology. The SEM micrographs depicted a well-defined superficial morphology with less porosity for the samples sintered at 1400 degrees C. For comparative analysis, the conductivity (S.cm(- 1)) was measured at varying temperatures (300-800 degrees C) for the samples sintered at 1300 and 1400 degrees C. Because of the large number of insulating phases produced by the incomplete sintering process, the samples sintered at 1300 degrees C had lower conductivities. A higher conductivity of 0.125 S.cm(- 1) was observed for La0.80Sr0.20Ga0.80Mg0.20O3 (LSGM), which was obtained using the citric acid (sintered at 1400 degrees C), which is in the range of earlier reported similar studies. The observed variation in the conductivity with respect to different phases of LSGM, the influence of the secondary phase, and the wt% of the constituents of LSGM are discussed.