BUSCADOR RECOLECTA

This dataset contains the information on our recent body of work on the electrodeposition of composite films comprising a calcium-deficient hydroxyapatite matrix with nanoscale Ag- or Zn-based particles and all the relevant data files. A fundamental study regarding the electrochemical synthesis of composite coatings with application in the orthopaedic field has been conducted. In particular, the electrodeposition of calcium phosphate coatings with Ag nanoparticles (AgNPs) from either a single electrolyte (one-step, 1S) or two electrolytes (two-step, 2S) on a b-Ti alloy (Ti-18Mo-6Nb-4Ta in wt%) was investigated. Pulse current deposition was implemented to produce the composite coatings by the 1S approach from a simple solution containing 42 mM Ca(NO3)2·4H2O, 25 mM NH4H2PO4, and 0.5 mM AgNO3 at 65 °C. Meanwhile, the calcium phosphate matrix was also deposited by pulse current, and Ag was afterwards grown by direct current from 0.1 M KNO3 + x mM AgNO3 (x = 5, 10) at 25 ºC (2S approach). The Ca/P ratio of the matrix was compatible with the formation of calcium-deficient hydroxyapatite (CDHA). The resulting Ag content in the composites could be varied between 4 and 13 wt% as a function of the working conditions. The 2S-derived coatings produced by electroplating Ag at j = –20.8 mA/cm2 from 0.1 M KNO3 + 10 mM AgNO3 furnished an optimal dispersion of the AgNPs on top of the CDHA matrix, while aggregation and/or dendritic growth was observed in other cases. Glow discharge optical emission spectrometry (GDOES) measurements indicated that a given amount of AgNPs becomes engulfed in the CDHA matrix during the 1S electrodeposition, whereas most of them decorate its outer surface in the 2S-derived coatings. The applicability of the two approaches was extended to the case of zinc oxide. ZnO-containing CDHA coatings in which the Zn element was homogeneously distributed across the film surface were obtained from 42 mM Ca(NO3)2·4H2O, 25 mM NH4H2PO4 and 1 mM Zn(NO3)2·6H2O at 65 ºC (1S approach). On the contrary, ZnO-NPs could be clearly observed when deposition from 5 mM KNO3 + 5 mM Zn(NO3)2 was performed at 70 ºC on top of previously grown CDHA (2S approach). The results indicated that the percentage and location of the antibacterial element (Ag, Zn) in the calcium phosphate matrix can be tuned on demand to a great extent by electrochemical means.

This dataset contains the information on our recent work on multilevel magnetic synapses for neuromorphic applications and all the relevant data files. In the present work, we exploit voltage-driven nitrogen ion motion in transition metal nitride (CoFeN) thin films (i.e., nitrogen magneto-ionics) to emulate biological synapses. In the proposed device, we have realized distinct multilevel non-volatile magnetic states for analog computing and multi-state storage. Moreover, essential synaptic functionalities of the human brain have been successfully simulated. The device exhibits an excellent synapse with a remarkable retention time (∼ 6 months), high switching ratio and large endurance (∼103), for hardware implementation of NC. This research provides new insight into exploiting magneto-ionic-based synaptic devices for spin-based neuromorphic systems.

This dataset contains the information on our recent body of work on Ag-induced transformation of FeMn alloys and all the relevant data files. In this work, attempt to explain the austenite-martensite phase transformation occurring in FeMn alloys upon additions of Ag. In the study, a combined experimental and theoretical approach are applied to reveal the mechanism behind the phase transformation. While equiatomic FeMn and FeMn-1Ag alloys possess a fully austenitic structure, a change in the crystallographic structure is observed upon addition of 3 and 5 wt% of Ag, where a mixture of γ austenite and ε martensite phases is observed. Compression tests reveal that such structural transition causes an increase of the yield stress. The evolution of microstructure with the Ag content can be understood from theoretical calculations which show that Ag atoms prefer the intrinsic stacking fault (ISF) sites, revealing lower energy for the ε atomic plane sequence. This causes local depletion of the electronic charge, therefore weakening the interatomic bonds at the ISF plane and facilitating the phase transition. In addition, the total energy difference between the γ and ε phases decreases upon Ag addition. This enables the coexistence of both phases in the sample with 5 wt% Ag. Both experimental and theoretical data agree that the magnetization value gradually increases upon Ag addition. This is due to the local stress that is introduced by Ag atoms, which expand the Ag-Fe and Ag-Mn first neighbour interatomic bonds compared to FeMn. This stress results in electronic charge transfer that locally alters the Fe and Mn atomic magnetic moments.

This dataset contains the information on our recent body of work on wireless magneto-ionics by bipolar electrochemistry approach and all the relevant data files. So far, magneto-ionics has been achieved through direct electrical connections to the actuated material. Here we evidence that an alternative way to reach such control exists in a wireless manner. Induced polarization in the conducting material immersed in the electrolyte, without direct wire contact, promotes wireless bipolar electrochemistry, an alternative pathway to achieve voltage-driven control of magnetism based on the same electrochemical processes involved in direct-contact magneto-ionics. A significant tunability of magnetization is accomplished for cobalt nitride thin films, including transitions between paramagnetic and ferromagnetic states. Such effects can be either volatile or non-volatile depending on the electrochemical cell configuration. These results represent a fundamental breakthrough that may inspire future device designs for applications in bioelectronics, catalysis, neuromorphic computing, or wireless communications.

This dataset contains the information on our recent body of work on the effect of the deposition of ZnO coating on degradation rate of FeMn porous alloys. Fe-based alloys are being studied as potential candidates for biodegradable implants; however, their degradation rates remain too slow. To accelerate biodegradation while simultaneously hindering biofilm formation, a ZnO coating was deposited onto porous equiatomic FeMn alloy discs by sol-gel method using dip coating. The effect of the ZnO coating on the microstructure, biodegradability, cytocompatibility, and antibacterial properties were investigated. Biodegradability experiments were performed by immersing the specimens in Hank's balanced salt solution and measuring ion release after up to 28 days of immersion. The experiments showed an increased degradation of the FeMn/ZnO sample due to Fe segregation towards the grain boundaries, formation of iron-manganese oxide, and limited formation of degradation products on ZnO. Further, indirect Saos-2 cell cytotoxicity testing in 24 h sample-conditioned media showed no significant cytotoxicity in concentrations equal to or below 50 %. In addition, the total biofilm biovolume formed by Staphylococcus aureus on the FeMn/ZnO surface was significantly reduced compared to the uncoated FeMn. Taken together, these results show that the ZnO coating on FeMn improves the degradation rate, maintains cytocompatibility, and reduces biofilm accumulation when compared to an uncoated FeMn alloy.

This dataset contains the information on our recent body of work on the study of magneto-ionic properties in structure/composition-engineered ternary nitrides and all the relevant data files. Magneto-ionics, an emerging approach to manipulate magnetism that relies on voltage-driven ion motion, holds the promise to boost energy efficiency in information technologies such as spintronic devices or future non-von Neumann computing architectures. For this purpose, stability, reversibility, endurance, and ion motion rates need to be synergistically optimized. Among various ions, nitrogen has demonstrated superior magneto-ionic performance compared to classical species such as oxygen or lithium. Here, we show that ternary Co1−xFexN compound exhibits an unprecedented nitrogen magneto-ionic response. Partial substitution of Co by Fe in binary CoN is shown to be favorable in terms of generated magnetization, cyclability and ion motion rates. Specifically, the Co0.35Fe0.65N films exhibit an induced saturation magnetization of 1500 emu cm–3, a magneto-ionic rate of 35.5 emu cm–3 s–1 and endurance exceeding 103 cycles. These values significantly surpass those of other existing nitride and oxide systems. This improvement can be attributed to the larger saturation magnetization of Co0.35Fe0.65 compared to individual Co and Fe, the nature and size of structural defects in as-grown films of different composition, and the dissimilar formation energies of Fe and Co with N in the various developed crystallographic structures.