Now showing items 10-29 of 29

    • A field induced ferromagnetic-like transition below 2.8 K in Li2CuO2: An experimental and theoretical study 

      Ortega Hertogs, Ricardo Upna; Jensen, P. J.; Rao, K. V.; Sapiña, F.; Beltrán, D.; Iqbal, Z.; Cooley, J. C.; Smith, J. L. (AIP Publishing, 1998)   Artículo / Artikulua  OpenAccess
      The low temperature magnetic properties of the Li2CuO2 compound have been investigated by means of superconducting quantum interference device magnetometry. We find in addition to an antiferromagnetic phase below 9.5 K a ...
    • Generating and measuring the anisotropic elastic behaviour of Co thin films with oriented surface nano-strings on micro-cantilevers 

      Madurga Pérez, Vicente Upna; Vergara Platero, José Upna; Favieres Ruiz, Cristina Upna (Springer, 2011)   Artículo / Artikulua  OpenAccess
      In this research, the elastic behaviour of two Co thin films simultaneously deposited in an off-normal angle method was studied. Towards this end, two Si micro-cantilevers were simultaneously coated using pulsed laser ...
    • Giant direct and inverse magnetocaloric effect linked to the same forward martensitic transformation 

      Pérez de Landazábal Berganzo, José Ignacio Upna; Recarte Callado, Vicente Upna; Sánchez-Alarcos Gómez, Vicente Upna; Beato López, Juan Jesús Upna; Rodríguez Velamazán, José Alberto; Sánchez Marcos, J.; Gómez Polo, Cristina Upna; Cesari, Eduard (Springer Nature, 2017)   Artículo / Artikulua  OpenAccess
      Metamagnetic shape memory alloys have aroused considerable attraction as potential magnetic refrigerants due to the large inverse magnetocaloric effect associated to the magnetic-field-induction of a reverse martensitic ...
    • Influence of defects on the irreversible phase transition in the Fe-Pd doped with Co and Mn 

      Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Pérez de Landazábal Berganzo, José Ignacio Upna; Recarte Callado, Vicente Upna; Sánchez-Alarcos Gómez, Vicente Upna (Rede Latino-Americana de Materiais, 2018)   Artículo / Artikulua  OpenAccess
      The appearance of BCT martensite in Fe-Pd-based ferromagnetic shape memory alloys, which develops at lower temperatures than the thermoelastic martensitic transition, deteriorates the shape memory properties. In a previous ...
    • Long-range atomic order and entropy change at the martensitic transformation in a Ni-Mn-In-Co metamagnetic shape memory alloy 

      Sánchez-Alarcos Gómez, Vicente Upna; Recarte Callado, Vicente Upna; Pérez de Landazábal Berganzo, José Ignacio Upna; Cesari, Eduard; Rodríguez Velamazán, José Alberto (MDPI, 2014)   Artículo / Artikulua  OpenAccess
      The influence of the atomic order on the martensitic transformation entropy change has been studied in a Ni-Mn-In-Co metamagnetic shape memory alloy through the evolution of the transformation temperatures under high-temperature ...
    • Loss of ductility due to the decarburation and Mn depletion of a coarse-grained TWIP steel 

      Cuevas Jiménez, Fernando de las Upna; Gil Sevillano, Javier (Consejo Superior de Investigaciones Científicas (CSIC), 2017)   Artículo / Artikulua  OpenAccess
      Se ha observado una clara transición de la ductilidad a tracción con el tamaño de grano D del orden 15 μm - 20 μm (1,50 μm ≤ D < 50 μm) en un acero TWIP, 22% de Mn, 0,6% de C (% en masa). Este comportamiento es una combinación ...
    • Low field magnetic and thermal hysteresis in antiferromagnetic dysprosium 

      Liubimova, Iuliia; Corró Moyá, Miguel; Torrens Serra, Joan; Recarte Callado, Vicente Upna; Pérez de Landazábal Berganzo, José Ignacio Upna; Kustov, Sergey (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      Magnetic and thermal hysteresis (difference in magnetic properties on cooling and heating) have been studied in polycrystalline Dy (dysprosium) between 80 and 250 K using measurements of the reversible Villari effect and ...
    • Magnetic anisotropy in isotropic and nanopatterned strongly exchange-coupled nanolayers 

      Vergara Platero, José Upna; Favieres Ruiz, Cristina Upna; Madurga Pérez, Vicente Upna (Springer, 2012)   Artículo / Artikulua  OpenAccess
      In this study, the fabrication of magnetic multilayers with a controlled value of the in-plane uniaxial magnetic anisotropy field in the range of 12 to 72 kA/m was achieved. This fabrication was accomplished by the ...
    • Magnetic transition in nanocrystalline soft magnetic alloys analyzed via ac inductive techniques 

      Gómez Polo, Cristina Upna; Pérez de Landazábal Berganzo, José Ignacio Upna; Recarte Callado, Vicente Upna; Vázquez, M.; Hernando, A. (American Physical Society, 2004)   Artículo / Artikulua  OpenAccess
      The magnetic transition in a FeSiBCuNb nanocrystalline alloy, associated with the decoupling of ferromagnetic crystallites around the Curie point of the residual amorphous matrix, is analyzed in this work through the ...
    • Magnetocaloric effect enhancement driven by intrinsic defects in a Ni45Co5Mn35Sn15 alloy 

      Sánchez-Alarcos Gómez, Vicente Upna; López García, Javier Upna; Unzueta, Iraultza; Pérez de Landazábal Berganzo, José Ignacio Upna; Recarte Callado, Vicente Upna; Beato López, Juan Jesús Upna; García, José Ángel; Plazaola, Fernando; Rodríguez Velamazán, José Alberto (Elsevier, 2019)   Artículo / Artikulua
      The influence of mechanically-induced defects on the magnetostructural properties is analyzed in a Ni-Co-Mn-Sn alloy subjected to soft milling and subsequent annealing treatments. It is found that, opposite to what occurs ...
    • Method for measurement of transition probabilities by laser-induced breakdown spectroscopy based on CSigma graphs. Application to Ca II spectral lines 

      Aguilera Andoaga, José Antonio Upna; Aragón Garbizu, Carlos Upna; Manrique Rosel, Javier (Elsevier, 2015)   Artículo / Artikulua  OpenAccess
      We propose a method for determination of transition probabilities by laser-induced breakdown spectroscopy that avoids the error due to self-absorption. The method relies on CSigma graphs, a generalization of curves of ...
    • People exposed to traffic noise in european agglomerations from noise maps: a critical review 

      Arana Burgui, Miguel Upna; San Martín Murugarren, Ricardo Upna; Salinas Hilburg, Juan Carlos (De Gruyter, 2014)   Artículo / Artikulua  OpenAccess
      Two of the main objectives of the European Directive on environmental noise are, firstly, to unify acoustic indices for assessing environmental noise and, secondly, to standardize assessment methodologies. The ultimate ...
    • Simple fabrication of ultrahigh aspect ratio nanostructures for enhanced antireflectivity 

      Domínguez Fernández, Sagrario; Cornago Santos, Ignacio; Bravo Larrea, Javier Upna; Pérez Conde, Jesús Upna; Choi, Hyungryul J.; Kim, Jeong-Gil; Barbastathis, George (American Vacuum Society, 2014)   Artículo / Artikulua  OpenAccess
      In this work, the authors present a novel fabrication process to create periodic nanostructures with aspect ratio as high as 9.6. These nanostructures reduce spectral reflectance of silicon to less than 4% over the broad ...
    • Strategic noise map of a major road carried out with two environmental prediction software packages 

      Arana Burgui, Miguel Upna; San Martín Murugarren, Ricardo Upna; San Martín Erviti, María Luisa Upna; Aramendía Santamaría, Emilio Upna (Springer Netherlands, 2010)   Artículo / Artikulua  OpenAccess
      The main objective of this study is to analyze the differences found in the results of noise mapping using two of the most popular software techniques for the prediction of environmental noise. The location selected ...
    • Strong angular dependence of resonant states in 2D dielectric cylinder rings 

      Andueza Unanua, Ángel María Upna; Pérez Conde, Jesús Upna; Sevilla Moróder, Joaquín Upna (AIP Publishing, 2018)   Artículo / Artikulua  OpenAccess
      We investigate collective resonators made of dielectric cylinders assembled as two-dimensional regular octagons and decagons. These structures exhibit collective resonance states that change their intensity with the incident ...
    • Structurally oriented nano-sheets in Co thin films: changing their anisotropic physical properties by thermally-induced relaxation 

      Vergara Platero, José Upna; Favieres Ruiz, Cristina Upna; Magén, César; Teresa, José María de; Ibarra, Manuel Ricardo; Madurga Pérez, Vicente Upna (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      We show how nanocrystalline Co films formed by separated oblique nano-sheets display anisotropy in their resistivity, magnetization process, surface nano-morphology and optical transmission. After performing a heat treatment ...
    • Study of optical fiber sensors for cryogenic temperature measurements 

      Miguel Soto, Verónica de Upna; Leandro González, Daniel Upna; López Aldaba, Aitor Upna; Beato López, Juan Jesús Upna; Pérez de Landazábal Berganzo, José Ignacio Upna; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel Upna (MDPI, 2017)   Artículo / Artikulua  OpenAccess
      In this work, the performance of five different fiber optic sensors at cryogenic temperatures has been analyzed. A photonic crystal fiber Fabry-Pérot interferometer, two Sagnac interferometers, a commercial fiber Bragg ...
    • Study of the martensitic transition in Ni-Mn-Sn-Ti ferromagnetic shape memory alloys 

      Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Pérez de Landazábal Berganzo, José Ignacio Upna; Recarte Callado, Vicente Upna; Sánchez-Alarcos Gómez, Vicente Upna (Rede Latino-Americana de Materiais, 2018)   Artículo / Artikulua  OpenAccess
      In the present work, mechanical spectroscopy measurements as a function of temperature and strain have been performed in (at.%) Ni50Mn37Sn13-xTix (x=0, 0.5 and 2) ferromagnetic shape memory alloys in order both to study ...
    • Thermal degradation of type I collagen from bones 

      Lambri, M. L.; Giordano, E. D.; Bozzano, P. B.; Pérez de Landazábal Berganzo, José Ignacio Upna; Recarte Callado, Vicente Upna (Tech Science Press, 2016)   Artículo / Artikulua  OpenAccess
      The denaturation processes of collagen in the temperature range between 450 K and 670 K are revealed through studies performed on cow rib bones by means of mechanical spectroscopy, differential scanning calorimetry, ...
    • Uncertainties caused by source directivity in room-acoustic investigations 

      San Martín Murugarren, Ricardo Upna; Arana Burgui, Miguel Upna (Acoustical Society of America (ASA), 2008)   Artículo / Artikulua  OpenAccess
      Although deviations in the measurement of acoustic parameters should be lower than the subjectively perceivable change in the corresponding parameter measured, this study reflects that directionality of sound sources could ...