TY - JOUR A1 - Salari, Farid A1 - Zocca, Andrea A1 - Bosetti, Paolo A1 - Hlaváček, Petr A1 - Italiano, Antonino A1 - Gobbin, Filippo A1 - Colombo, Paolo A1 - Kühne, Hans-Carsten A1 - Sglavo, Vincenzo M. T1 - Powder-bed 3D printing by selective activation of magnesium phosphate cement: Determining significant processing parameters and their effect on mechanical strength N2 - The present work addresses powder bed binder jetting additive manufacturing by selective magnesium phosphate cement activation. Despite the potential of this technology to aid the digitalization of the construction industry, the effect of processing parameters on the mechanical performance of printed materials has not yet been studied to generate a guideline for the further development of the technology. Statistical methodologies were used to screen the effect of four printing process parameters (printing speed, layer thickness, raster angle, and build direction on flexural and compressive strength). As the exploited technology works with constant fluid pressure, the physical interpretation of the effect of each factor can be considered taking into account the interactions between the binder materials in the powder bed. Analysis of variance (ANOVA) indicated that printing speed and layer thickness significantly affect mechanical performances. Furthermore, the layout of samples for the printing process is preferable to be parallel the printhead movement. An anisotropic behavior was observed, and the samples subjected to compressive forces parallel to the layer plane possessed lower strength values. This effect can be interpreted as a result of a weak area of low density in between layers, leading to a pronounced delamination under compression. Even though the strength of the printed material is not suitable for a structural concrete, it can be marginally improved by design of experiment and optimized for non-structural applications, such as for porous artificial stone. Design of experiment coupled with ANOVA methods can be used in the future to support the development of novel material mixtures, thus expanding the fields of application of this novel additive manufacturing technology. KW - Concrete 3D-printing KW - Particle-bed binder jetting KW - Design of experiment PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601654 DO - https://doi.org/10.1016/j.oceram.2024.100609 VL - 18 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-60165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Galleani, Gustavo A1 - Lodi, Thiago A. A1 - Conner, Robin L. A1 - Jacobsohn, Luiz G. A1 - de Camargo, Andrea T1 - Photoluminescence and X-ray induced scintillation in Gd3+-Tb3+ co-doped fluoride-phosphate glasses, and derived glass-ceramics containing NaGdF4 nanocrystals N2 - The glass system (50NaPO3–20BaF2–10CaF2–20GdF3)-xTbCl3 with x = 0.3, 1, 3, 5, and 10 wt % was investigated. We successfully produced transparent glass ceramic (GC) scintillators with x = 1 through a melt-quenching process followed by thermal treatment. The luminescence and crystallization characteristics of these materials were thoroughly examined using various analytical methods. The nanocrystallization of Tb3+-doped Na5Gd9F32 within the doped fluoride-phosphate glasses resulted in enhanced photoluminescence (PL) and radioluminescence (RL) of the Tb3+ ions. The GC exhibited an internal PL quantum yield of 33 % and the integrated RL intensity across the UV-visible range was 36 % of that reported for the commercial BGO powder scintillator. This research showcases that Tb-doped fluoridephosphate GCs containing nanocrystalline Na5Gd9F32 have the potential to serve as efficient scintillators while having lower melting temperature compared to traditional silicate and germanate glasses. KW - Glass scintillator KW - Fluoride phosphate glasses KW - Gd3+ KW - Tb3+ PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-603588 DO - https://doi.org/10.1016/j.omx.2023.100288 VL - 21 SP - 1 EP - 9 PB - Elsevier B.V. AN - OPUS4-60358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - da Costa, P. F. G. M. A1 - Merízio, L. G. A1 - Wolff, N. A1 - Terraschke, H. A1 - de Camargo, Andrea T1 - Real-time monitoring of CdTe quantum dots growth in aqueous solution N2 - Quantum dots (QDs) are remarkable semiconductor nanoparticles, whose optical properties are strongly size-dependent. Therefore, the real-time monitoring of crystal growth pathway during synthesis gives an excellent opportunity to a smart design of the QDs luminescence. In this work, we present a new approach for monitoring the formation of QDs in aqueous solution up to 90 °C, through in situ luminescence analysis, using CdTe as a model system. This technique allows a detailed examination of the evolution of their light emission. In contrast to in situ absorbance analysis, the in situ luminescence measurements in reflection geometry are particularly advantageous once they are not hindered by the concentration increase of the colloidal suspension. The synthesized particles were additionally characterized using X-ray diffraction analysis, transition electron microscopy, UV-Vis absorption and infrared spectroscopy. The infrared spectra showed that 3-mercaptopropionic acid (MPA)-based thiols are covalently bound on the surface of QDs and microscopy revealed the formation of CdS. Setting a total of 3 h of reaction time, for instance, the QDs synthesized at 70, 80 and 90 °C exhibit emission maxima centered at 550, 600 and 655 nm. The in situ monitoring approach opens doors for a more precise achievement of the desired emission wavelength of QDs. KW - CdTe quantum dots KW - In situ synthesis KW - Real time growth control PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-603596 DO - https://doi.org/10.1038/s41598-024-57810-8 VL - 14 IS - 1 SP - 1 EP - 11 PB - Springer Science and Business Media LLC AN - OPUS4-60359 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, Fengchan A1 - Oiticica, Pedro Ramon Almeida A1 - Abad-Arredondo, Jaime A1 - Arai, Marylyn Setsuko A1 - Oliveira, Osvaldo N. A1 - Jaque, Daniel A1 - Fernandez Dominguez, Antonio I. A1 - de Camargo, Andrea A1 - Haro-González, Patricia T1 - Brownian Motion Governs the Plasmonic Enhancement of Colloidal Upconverting Nanoparticles N2 - Upconverting nanoparticles are essential in modern photonics due to their ability to convert infrared light to visible light. Despite their significance, they exhibit limited brightness, a key drawback that can be addressed by combining them with plasmonic nanoparticles. Plasmon-enhanced upconversion has been widely demonstrated in dry environments, where upconverting nanoparticles are immobilized, but constitutes a challenge in liquid media where Brownian motion competes against immobilization. This study employs optical tweezers for the three-dimensional manipulation of an individual upconverting nanoparticle, enabling the exploration of plasmon-enhanced upconversion luminescence in water. Contrary to expectation, experiments reveal a long-range (micrometer scale) and moderate (20%) enhancement in upconversion luminescence due to the plasmonic resonances of gold nanostructures. Comparison between experiments and numerical simulations evidences the key role of Brownian motion. It is demonstrated how the three-dimensional Brownian fluctuations of the upconverting nanoparticle lead to an “average effect” that explains the magnitude and spatial extension of luminescence enhancement. KW - Upconversion KW - Plasmon enhancement KW - Optical tweezers KW - Brownian motion KW - Nanoparticles PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-603551 DO - https://doi.org/10.1021/acs.nanolett.4c00379 VL - 24 IS - 12 SP - 3785 EP - 3792 PB - American Chemical Society (ACS) AN - OPUS4-60355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -