Person:
Peña Moreno, Álvaro

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First Name
Álvaro
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Peña Moreno
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Universidad Complutense de Madrid
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Now showing 1 - 6 of 6
  • Publication
    A feasible pathway to stabilize monoclinic and tetragonal phase coexistence in barium titanate-based ceramics
    (Royal Soc. Chemistry, 2022-11) Necib, Jallouli; López Sánchez, Jesús; Rubio Marcos, Fernando; Serrano, Aída; Navarro Palma, Elena; Peña Moreno, Álvaro; Taoufik, Mnasri; Smari, Mourad; Rojas Hernández, Rocío Estefanía; Carmona Tejero, Noemí; Marín Palacios, María Pilar
    Multiphase coexistence has attracted significant interest in recent years because its control has entailed a significant breakthrough for the piezoelectric activity enhancement of lead-free piezoelectric oxides. However, the comprehension of phase coexistence still has many controversies including an adequate synthesis process and/or the role played by crystalline phases in functional properties. In this study, functional barium titanate [BaTiO_(3), (BTO)]-based materials with tunable functional properties were obtained by compositional modification via Bismuth (Bi) doping. Towards this aim, we systematically synthesized BTO-based materials by a sol-gel method, focusing on the control of Bi substitution in the BaTiO_(3) structure. In particular, we found that the substitution of Bi^(+3) leads to the stabilization of a monoclinic-tetragonal (M-T) phase boundary close to room temperature, which facilities the polarization process of the system. As a surprising result, we believe that the simple and cost-effective strategy and design principles described in this work open up the possibility of obtaining BTO-based lead-free ceramics with enhanced properties induced by the stabilization of the phase coexistence, expanding their application range.
  • Publication
    Correction: A feasible pathway to stabilize monoclinic and tetragonal phase coexistence in barium titanate-based ceramics
    (Royal Soc. Chemistry) Necib, Jallouli; López Sánchez, Jesús; Rubio Marco, Fernando; Serrano, Aída; Navarro Palma, Elena; Peña Moreno, Álvaro; Mnasri, Taoufik; Smari, Mourad; Rojas Hernández, Rocío Estefanía; Carmona Tejero, Noemí; Marín Palacios, María Pilar
  • Publication
    Optimization of multilayer graphene-based gas sensors by ultraviolet photoactivation
    (Elsevier, 2022-11-01) Peña Moreno, Álvaro; Matatagui Cruz, Daniel; Ricciardella, Filiberto; Sacco, Leandro; Vollebregt, Sten; Otero, Daniel; López Sánchez, Jesús; Marín Palacios, Pilar; Horrillo, Mari Carmen
    Nitrogen dioxide (NO2) is a potential hazard to human health at low concentrations, below one part per million (ppm). NO2 can be monitored using gas sensors based on multi-layered graphene operating at ambient temperature. However, reliable detection of concentrations on the order of parts per million and lower is hindered by partial recovery and lack of reproducibility of the sensors after exposure. We show how to overcome these longstanding problems using ultraviolet (UV) light. When exposed to NO2, the sensor response is enhanced by 290 % − 550 % under a 275 nm wavelength light emitting diode irradiation. Furthermore, the sensor’s initial state is completely restored after exposure to the target gas. UV irradiation at 68 W/m2 reduces the NO2 detection limit to 30 parts per billion (ppb) at room temperature. We investigated sensor performance optimization for UV irradiation with different power densities and target gases, such as carbon oxide and ammonia. Improved sensitivity, recovery, and reproducibility of UV-assisted graphene-based gas sensors make them suitable for widespread environmental applications.
  • Publication
    Real-time monitoring of breath biomarkers with a magnetoelastic contactless gas sensor: a proof of concept
    (MDPI, 2022-10) Peña Moreno, Álvaro; Aguilera, Juan Diego; Matatagui Cruz, Daniel; Presa Muñoz del Toro, Patricia de la; Horrillo, Carmen; Hernando Grande, Antonio; Marín Palacios, María Pilar
    In the quest for effective gas sensors for breath analysis, magnetoelastic resonance-based gas sensors (MEGSs) are remarkable candidates. Thanks to their intrinsic contactless operation, they can be used as non-invasive and portable devices. However, traditional monitoring techniques are bound to slow detection, which hinders their application to fast bio-related reactions. Here we present a method for real-time monitoring of the resonance frequency, with a proof of concept for real-time monitoring of gaseous biomarkers based on resonance frequency. This method was validated with a MEGS based on a Metglass 2826 MB microribbon with a polyvinylpyrrolidone (PVP) nanofiber electrospun functionalization. The device provided a low-noise (RMS = 1.7 Hz), fast (<2 min), and highly reproducible response to humidity (Delta f = 46-182 Hz for 17-95% RH), ammonia (Delta f = 112 Hz for 40 ppm), and acetone (Delta f = 44 Hz for 40 ppm). These analytes are highly important in biomedical applications, particularly ammonia and acetone, which are biomarkers related to diseases such as diabetes. Furthermore, the capability of distinguishing between breath and regular air was demonstrated with real breath measurements. The sensor also exhibited strong resistance to benzene, a common gaseous interferent in breath analysis.
  • Publication
    Generation of defective few-layered graphene mesostructures by high-energy ball milling and their combination with FeSiCuNbB microwires for reinforcing microwave absorbing properties
    (American Chemical Society, 2023-01-06) López Sánchez, Jesús; Peña Moreno, Álvaro; Serrano, Aida; Campo, Adolfo, del; Rodríguez De La Fuente, Óscar; Carmona Tejero, Noemí; Matatagui Cruz, Daniel; Horrillo, María del Carmen; Rubio Zazo, Juan; Navarro Palma, Elena; Marín Palacios, María Pilar
    Defective few-layered graphene mesostructures (DFLGMs) are produced from graphite flakes by high-energy milling processes. We obtain an accurate control of the generated mesostructures, as well as of the amount and classification of the structural defects formed, providing a functional material for microwave absorption purposes. Working under far-field conditions, competitive values of minimum reflection loss coefficient (RL_(min)) = −21.76 dB and EAB = 4.77 dB are achieved when DFLGMs are immersed in paints at a low volume fraction (1.95%). One step forward is developed by combining them with the excellent absorption behavior that offers amorphous Fe_(73.5)Si_(13.5)B_(9)Cu_(1)Nb microwires (MWs), varying their filling contents, which are below 3%. We obtain a RLmin improvement of 47% (−53.08 dB) and an EAB enhancement of 137% (4 dB) compared to those obtained by MW-based paints. Furthermore, a f_(min) tunability is demonstrated, maintaining similar RL_(min) and EAB values, irrespective of an ideal matching thickness. In this scenario, the Maxwell-Garnet standard model is valid, and dielectric losses mainly come from multiple reflections, interfacial and dielectric polarizations, which greatly boost the microwave attenuation of MWs. The present concept can remarkably enhance not only the MW attenuation but can also apply to other microwave absorption architectures of technological interest by adding low quantities of DFLGMs.
  • Publication
    Ultrasensitive NO_(2 )gas sensor with insignificant NH3-interference based on a few-layered mesoporous graphene
    (Elsevier, 2021-05-15) Matatagui Cruz, Daniel; López Sánchez, Jesús; Peña Moreno, Álvaro; Serrano, Aída; Campo, Adolfo del; Rodríguez De La Fuente, Óscar; Carmona Tejero, Noemí; Navarro Palma, Elena; Marín Palacios, María Pilar; Horrillo, María del Carmen
    Few-layered mesoporous graphene (FLMG) is employed as a sensing material to develop an innovative and high-sensitivity room temperature NO_(2) sensor through a simple manufacturing process. For this purpose, sensing material is optimized at 100 min by a high-energy milling process where natural graphite is used as a precursor: it is an inexpensive, sustainable and suitable active material. The large number of defects created and the enhanced degree of mesoporosity produced during the milling process determine the physical principles of operation of the designed device. NO_(2) gas sensing tests reveal an improved and selective performance with a change in resistance of ∼16 % at 0.5 ppm under ultraviolet photo-activation, establishing a detection limit around ∼25 ppb. Interestingly, the response of the developed sensor to humidity is independent in the measured range (0–33 % relative humidity at 25 °C) and the dependency to the presence of NH3 is rather poor as well (∼1.5 % at 50 ppm).