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Influence of pulp industry dregs on the physical and mechanical properties of mortar
2026 - CESAR, LUIS F. M.; ALBAS, AGDA E. de S.; LIMA, NELSON B. de; AKASAKI, JORGE L.; MORAES, JOAO C. S.
This study examined the constituents and evaluated the effects of incorporating a pulp industry residue (dregs) on the physical and mechanical properties of mortar. The properties of the mortar constituents were evaluated using thermogravimetry–differential scanning calorimetry (TG-DSC), energy-dispersive spectroscopy (EDS), X-ray Fluorescence spectroscopy (XRF), X-ray diffraction (XRD), and tests specified in standards NBR 16605 (2017), NBR 11579 (2013), and NM 18 (2012). The hardened mortar was evaluated through mechanical testing (NBR 7215 2019), water absorption testing (NBR 9778 2005), and mercury intrusion porosimetry. XRD data from dregs treated at different temperatures were analyzed using the Rietveld refinement method. The specific gravities of the cement, dregs, and sand were 3.13, 2.58 and 2.62 g/cm3, respectively. The main chemical elements detected in the dregs (> 1 atom%) were Ca, Mg, Mn, Si, Na, S, and Al. Thermal analysis revealed two endothermic events: the evaporation of sulfur-containing compounds and the decomposition of calcium magnesium carbonate. Lattice parameters were obtained for the Ca0.87Mg0.13(CO3)2 phase, observed in the dregs treated at 100 and 500 °C, and for the CaO and MgO phases, observed after treatment at 750 °C. To evaluate compressive strength, water absorption, and porosity, mortars were prepared under three distinct conditions: one without dregs; four with dregs added to the mixture, keeping the cement and sand contents constant; and four with dregs as a partial replacement for Portland cement, keeping the sand content constant. Compressive strength decreases with increasing dregs content, with a more pronounced reduction when Portland cement is replaced by dregs than when dregs are added. Incorporating 40 wt% dregs reduced compressive strength by 73% under the Substitution condition and 52% under the Addition condition, relative to the reference mortar without dregs. This reduction in compressive strength is associated with increased water absorption and porosity as the dregs content increases.
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Impact of high-energy milling synthesis on the electrostriction performance of Ce0.9Zr0.1O2
2026 - MARQUES, LARISSA S.; FERLAUTO, ANDRE S.; FONSECA, FABIO C.; KABIR, AHSANUL; KOUKOULIS, DIMITRIOS; ISLAM, KHONDOKER N.; ESPOSITO, VINCENZO; FLORIO, DANIEL Z. de
Electrostrictors have the capacity to unidirectionally convert electrical energy into a mechanical response. The best electrostrictors known so far have a high content of toxic lead (Pb) in their composition. To solve this environmental issue, research efforts shifted to lead-free electrostrictor compositions, such as the ceria-based compounds. Ceria-based materials present “giant” electrostriction, and amongst them, Ce0.9Zr0.1O2 can be a suitable lead-free substitute. To advance in the implementation of green chemistry principles for electromechanically active materials and to determine the ramifications of its employment on functional properties of fluorite-based CeO2 - ZrO2 mixed oxides, we successfully synthesized a Ce0.9Zr0.1O2 solid solution using a high-energy milling-assisted method. Nanometric milled powders exhibit the fluorite structure and a homogeneous dispersion of Zr in the ceria matrix that is preserved after sintering dense pellets. Soft X-ray absorption measurements reveal the predominance of Ce4+ species and the limited presence of oxygen vacancies in Ce0.9Zr0.1O2. Impedance spectroscopy measurements reveal highly resistive behavior, characterized by a strong overlap of grain and grain boundary contributions. The Ce0.9Zr0.1O2 dielectric constant measured at room temperature is twice that of undoped ceria, εr ≈ 66, which is related to improved electromechanical response. Longitudinal electrostriction measurements support this assessment, reaching values of up to 1.7⋅10−17 m2 V−2 near the kHz frequency.
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Formation of dysprosium doped yttria (YDy) powders with EPR response
2026 - SANTOS, S. C.; RODRIGUES JR, O.; CALDAS, L.
From rare-earth (RE) based oxides, yttria (Y2O3) has unique solid-state characteristics, and as doped with RE-ions, exhibits excellent spectroscopic properties. However, its potentiality in radiation dosimetry field has been rarely explored. Based on this context, the present paper reports an alternative hydrothermal synthesis based on low temperature and environmental pressure to form dysprosium doped yttria (YDy) nanoparticles with potential application in radiation dosimetry. According to the results, YDy compositions with up to 2 at%Dy exhibited cubic C-type form, rounded-like shape, and narrow particle size distribution with the average size inferior to 700 nm. In addition, by Electron Paramagnetic Resonance (EPR), it was seen that the EPR response of the YDy nanoparticles relied on the content of dysprosium, while the YDy composition containing 0.1 at%Dy exhibited the maximum spin concentration 23.1027s.mm−3 among all compositions. These innovative findings are useful processing parameters to advance toward the formation of shaped bodies by additive manufacturing, and use in solid state dosimetry.
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Novel chemometric Raman approach for spatially resolved quantification of graft distribution in anion exchange membranes
2026 - BERECZKI, ALLAN; BARBOSA, ANDREY da S.; WETTER, NIKLAUS U.; DEKEL, DARIO R.; SANTIAGO, ELISABETE I.
Precise control of the graft distribution, represented by the degree of grafting (DoG), in anion exchange membranes (AEMs) prepared by radiation-induced grafting (RIG), is critical for alkaline fuel cells' performance, especially aiming to improve water management. However, current methods offer only bulk or qualitative assessments of DoG, limiting the ability to understand and optimize local membrane properties. In this work, we present a novel Raman-based chemometric method for the spatially resolved quantification of DoG using micro-Raman spectroscopy. By applying classical least squares (CLS) fitting to decompose Raman spectra into contributions from the polymer base and grafted side chains, we establish a direct correlation between CLS scores and the local DoG. This approach enables, for the first time to our knowledge, the use of a multivariate technique for quantitative mapping of grafting profiles across the membrane cross-section using a widely accessible and non-destructive technique. The method is validated on membranes with known grafting levels and applied to asymmetric DoG AEMs, revealing detailed insights into spatial variations in functionalization. Moreover, the approach is broadly applicable to any grafted copolymer system with side-chain functionalization, beyond the specific membranes studied here. By combining spatially resolved measurement with rigorous chemometric analysis, this technique offers a robust tool for the design and optimization of next-generation ion-conducting membranes in electrochemical energy systems.