103 documents found, page 1 of 11
Engineering Pb-free relaxor ferroelectric thin films for low voltage energy sto...
Ribeiro, Duarte J. M.; Nair, Surya Kiran Puravankara; Ravikumar, Jayakrishnan AMpattu; Oliveira, João; Magagnin, Grégoire; Albertini, DavidPulsed power technologies demand dielectric capacitors that possess a high energy storage density and efficiency at low applied electric fields/voltages. In this work, we engineered the morphology of lead-free \( 0.85[0.6\text{Ba}(\text{Zr}_{0.2}\text{Ti}_{0.8})\text{O}_3–0.4(\text{Ba}_{0.7}\text{Ca}_{0.3})\text{TiO}_3]–0.15\text{SrTiO}_3 \) (BZCT–STO) epitaxial thin films, fabricated using the pulsed laser dep...
Piezoelectric and pyroelectric properties of organic MDABCO-NH4Cl3 perovskite f...
Baptista, Rosa M. F.; Silva, Bruna Machado; Oliveira, João; Almeida, B. G.; Castro, Maria Cidália Rodrigues; Rodrigues, Pedro António VeigaThis study describes the synthesis and characterization of the lead-free organic ferroelectric perovskite N-methyl-N’-diazabicyclo [2.2.2]octonium)-ammonium trichloride (MDABCO-NH4Cl3). The electrospinning technique was employed to obtain nanofibers embedded with this perovskite in a PVC polymer for hybrid fiber production. The dielectric, piezoelectric, and pyroelectric properties of these fibers were carefull...
Ferroelectric behavior arising from polar topologies in epitaxially strained Sr...
Rodrigues, Tiago; Silva, José Pedro Basto; Figueiras, Fábio; Soares, M. R.; Vilarinho, R.; Moreira, J. Agostinho; Çaha, Ihsan; Deepak, Francis LeonardIn this work, we show that epitaxially strained SrTiO3-δ thin films, grown by ion-beam sputtering onto (001)Nb: SrTiO3 substrates, exhibit a ferroelectric behavior. At the atomic-scale, through high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images, it was possible to identify the presence of polar nanoregions with non-trivial polar topological structures in the SrTiO3-δ fil...
Bioinspired cyclic dipeptide functionalized nanofibers for thermal sensing and ...
Santos, Daniela; Baptista, Rosa Maria Ferreira; Handa, Adelino; Almeida, B. G.; Rodrigues, Pedro V.; Torres, Ana R.; Machado, A. V.; Belsley, M.Nanostructured dipeptide self-assemblies exhibiting quantum confinement are of great interest due to their potential applications in the field of materials science as optoelectronic materials for energy harvesting devices. Cyclic dipeptides are an emerging outstanding group of ring-shaped dipeptides, which, because of multiple interactions, self-assemble in supramolecular structures with different morphologies ...
Nanostructured electrospun fibers with self-assembled cyclo-L-Tryptophan-L-Tyro...
Santos, Daniela; Baptista, Rosa M. F.; Handa, Adelino; Almeida, B. G.; Rodrigues, Pedro V.; Castro, Cidália; Machado, A. V.; Rodrigues, Manuel J. L. F.The potential use of nanostructured dipeptide self-assemblies in materials science for energy harvesting devices is a highly sought-after area of research. Specifically, aromatic cyclo-dipeptides containing tryptophan have garnered attention due to their wide-bandgap semiconductor properties, high mechanical rigidity, photoluminescence, and nonlinear optical behavior. In this study, we present the development of...
Synthesis, structural and dielectric properties of Ca3Mn2O7 thin films prepared...
Silva, Bruna Machado; Oliveira, J.; Rebelo, Tiago Miguel Pereira; Bayzi Isfahani, Vahideh; Rocha-Rodrigues, P.; Lekshmi, N.; Belo, J. H.; Deepak, F. L.Multiferroic Ruddlesden-Popper Ca3Mn2O7 thin films were prepared by laser ablation on SrTiO3 substrates. For low laser fluences and high oxygen pressures, the films assumed the CaMnO3 Pnma orthorhombic structure. However, by increasing fluence and decreasing the oxygen pressure, the Ca3Mn2O7 phase is achieved through a post-deposition annealing treatment. Furthermore, the ferroelectric phase A21am was observed ...
A polymorph of dipeptide halide glycyl-L-alanine hydroiodide monohydrate: cryst...
Baptista, Rosa Maria Ferreira; Gomes, Clara S. B.; Silva, Bruna Machado; Oliveira, joão; Almeida, B. G.; Castro, Maria Cidália RodriguesA polymorph of glycyl-L-alanine HI.H2O is synthesized from chiral cyclo-glycyl-L-alanine dipeptide. The dipeptide is known to show molecular flexibility in different environments, which leads to polymorphism. The crystal structure of the glycyl-L-alanine HI.H2O polymorph is determined at room temperature and indicates that the space group is polar (P21), with two molecules per unit cell and unit cell parameters...
Electrospun microstructured biopolymer fibers containing the self-assembled Boc...
Handa, Adelino; Baptista, Rosa Maria Ferreira; Santos, Daniela; Silva, Bruna; Rodrigues, Ana Rita Oliveira; Oliveira, João; Almeida, B. G.Hybrid biomaterials were engineered using the electrospinning technique, incorporating the dipeptide Boc–L-phenylalanyl–L-isoleucine into microfibers composed of biocompatible polymers. The examination by scanning electron microscopy affirmed the morphology of the microfibers, exhibiting diameters ranging between 0.9 and 1.8 µm. The dipeptide self-assembles into spheres with a hydrodynamic size between 0.18 and...
Lead-free MDABCO-NH4I3 perovskite crystals embedded in electrospun nanofibers
Baptista, Rosa Maria Ferreira; Moreira, Gonçalo; Silva, Bruna; Oliveira, João; Almeida, B. G.; Castro, Maria Cidália RodriguesIn this work, we introduce lead-free organic ferroelectric perovskite N-methyl-N′-diazabicyclo [2.2.2]octonium)–ammonium triiodide (MDABCO-NH4I3) nanocrystals embedded in three different polymer fibers fabricated by the electrospinning technique, as mechanical energy harvesters. Molecular ferroelectrics offer the advantage of structural diversity and tunability, easy fabrication, and mechanical flexibility. Organ...
Magnetoliposomes containing multicore nanoparticles and a new antitumor thienop...
Lopes, Fábio A. C.; Fernandes, André V. F.; Rodrigues, Juliana M.; Queiroz, Maria João R. P.; Almeida, B. G.; Pires, Ana; Pereira, André M.Multicore magnetic nanoparticles of manganese ferrite were prepared using carboxymethyl dextran as an agglutinating compound or by an innovative method using melamine as a cross-coupling agent. The nanoparticles prepared using melamine exhibited a flower-shape structure, a saturation magnetization of 6.16 emu/g and good capabilities for magnetic hyperthermia, with a specific absorption rate (SAR) of 0.14 W/g. M...