Open Access
Study of optical fiber sensors for cryogenic temperature measurements
(MDPI, 2017) Miguel Soto, Verónica de; Leandro González, Daniel; López Aldaba, Aitor; Beato López, Juan Jesús; Pérez de Landazábal Berganzo, José Ignacio; Auguste, Jean-Louis; Jamier, Raphael; Roy, Philippe; López-Amo Sáinz, Manuel; Ingeniaritza Elektrikoa eta Elektronikoa; Fisika; Institute for Advanced Materials and Mathematics - INAMAT2; Institute of Smart Cities - ISC; Ingeniería Eléctrica y Electrónica; Física; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
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 grating (FBG), and a -phase shifted fiber Bragg grating interrogated in 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 grating (FBG), and a π-phase shifted fiber Bragg grating interrogated in a random distributed feedback fiber laser have been studied. Their sensitivities and resolutions as sensors for cryogenic temperatures have been compared regarding their advantages and disadvantages. Additionally, the results have been compared with the given by a commercial optical backscatter reflectometer that allowed for distributed temperature measurements of a single mode fiber.
Open Access
Study of the martensitic transition in Ni-Mn-Sn-Ti ferromagnetic shape memory alloys
(Rede Latino-Americana de Materiais, 2018) Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente; Sánchez-Alarcos Gómez, Vicente; Fisika; Institute for Advanced Materials and Mathematics - INAMAT2; Física; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
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 martensitic transition phenomenon and also to determine its temperature of appearance. For mechanical spectroscopy measurements, a five elements piezoelectric device recently developed has been used. In addition, other characterization techniques as, differential thermal analysis and superconducting quantum interference magnetic spectroscopy, were also used. Besides, relaxation processes near the martensitic transition temperature have been also observed.
Open Access
A comprehensive analysis of the absorption spectrum of conducting ferromagnetic wires
(IEEE, 2012) Liberal Olleta, Íñigo; Ederra Urzainqui, Íñigo; Gómez Polo, Cristina; Labrador Otamendi, Alberto; Pérez de Landazábal Berganzo, José Ignacio; Gonzalo García, Ramón; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa; Física; Fisika
A detailed analysis of the absorption spectrum of conductive ferromagnetic wires is presented. The absorption spectrum is computed from the solution to the scattering problem, and circuit models are formulated to clarify the interplay between losses, skin-effect and wire geometry. Both infinitely-long wires and the axial resonances introduced by finite-length wires are considered. The theoretical results are validated experimentally through measurements within a metallic rectangular waveguide.
Open Access
Thermal degradation of type I collagen from bones
(Tech Science Press, 2016) Lambri, Melania Lucila; Giordano, E. D.; Bozzano, P. B.; Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente; Fisika; Institute for Advanced Materials and Mathematics - INAMAT2; Física; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
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, thermogravimetry, scanning electron microscopy and infrared spectroscopy. The conformational change of the collagen molecules from a triple helix structure to a random coil was found at around 510 K. It was determined that the transformation is developed through the viscous movement of fibrils with an activation energy of (127 ± 8) kJ/mol. The second stage of massive bulk deterioration of the collagen was found at around 600 K, which leads to the loss of the mechanical integrity of the bulk collagen. In addition, an easy-to-handle viscoelastic procedure for obtaining the activation energy of the denaturation process from mechanical spectroscopy studies was also shown.
Open Access
119Sn Mössbauer spectroscopy for assessing the local stress and defect state towards the tuning of Ni-Mn-Sn alloys
(AIP Publishing, 2017) Unzueta, Iraultza; López García, Javier; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Fisika; Institute for Advanced Materials and Mathematics - INAMAT2; Física
The influence of defects and local stresses on the magnetic properties and martensitic transformation in Ni50Mn35Sn15 is studied at macroscopic and atomic scale levels. We show that both the structural and magnetic properties of the alloy are very sensitive to slight microstructural distortions. Even though no atomic disorder is induced by milling, the antiphase boundaries linked to dislocations promote the antiferromagnetic coupling of Mn, resulting in a significant decrease in the saturation magnetization. On the other hand, the temperature range of the transformation is considerably affected by the mechanically induced local stresses, which in turn does not affect the equilibrium temperature between the austenitic and martensitic phases. Finally, we demonstrate that the recovery of the martensitic transformation is directly related to the intensity of the non-magnetic component revealed by 119Sn Mössbauer spectroscopy. This result opens the possibility of quantifying the whole contribution of defects and the local stresses on the martensitic transformation in Ni-Mn-Sn alloys.
Open Access
Outstanding role of the magnetic entropy in arrested austenite in an ordered Ni45Mn36.7In13.3Co5 metamagnetic shape memory alloy
(Elsevier, 2019) Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente; Sánchez-Alarcos Gómez, Vicente; Jiménez Ruiz, M.; Cesari, Eduard; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
The relevance of the entropy and in particular the outstanding role of the magnetic contribution is analyzed in a non-equilibrium arrested austenite phase in a Ni 45 Mn 36.7 In 13.3 Co 5 metamagnetic shape memory alloy. The Debye and Bragg-Williams approximations have been used to analyze and quantify the vibrational and magnetic contributions respectively, to the total entropy change linked to the martensitic transformation. The sign on the entropy change associated to the forward austenite to martensite transformation is different depending on whether it occurs at low or at high temperature as a consequence of the different vibrational and magnetic contributions.
Open Access
Entropy change caused by martensitic transformations of ferromagnetic shape memory alloys
(MDPI, 2017) L'vov, Victor A.; Cesari, Eduard; Kosogor, Anna; Torrens Serra, Joan; Recarte Callado, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Física; Fisika
In this paper, our most recent findings on the influence of magnetic order on the main transformational caloric and elastic properties of shape memory alloys (SMAs) are reviewed. It is argued that ferromagnetic order has a strong influence on the temperature interval of martensitic transformation (MT), the characteristics of stress-induced MT, and the shear elastic modulus of SMA. The problem of separation of the magnetic contributions to the entropy change ΔS and heat Q exchanged in the course of martensitic transformation (MT) of SMA is considered in general terms, and theoretical formulas enabling the solution of the problem are presented. As an example, the ΔS and Q values, which were experimentally determined for Ni-Mn-Ga and Ni-Fe-Ga alloys with different Curie temperatures TC and MT temperatures TM, are theoretically analyzed. It is shown that for Ni-Mn-Ga martensites with TM < TC, the ratio of elastic and magnetic contributions to the entropy change may be greater or smaller than unity, depending on the temperature difference TC – TM.
Open Access
Changes in the crystalline degree in neutron irradiated EPDM viewed through infrared spectroscopy and inelastic neutron scattering
(Rede Latino-Americana de Materiais, 2018) Lambri, Osvaldo Agustín; Giordano, E. D.; Bonifacich, Federico Guillermo; Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente; Física; Fisika; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
The changes in the degree of crystallinity in commercial Ethylene Propylene Diene rubber-type M (EPDM) irradiated with neutrons at different doses has been studied by means of inelastic neutron scattering and infrared absorption spectroscopy experiments. EPDM samples were taken from the housing of non-ceramic electrical insulators which are used in outdoor transmission lines of 66 kV. Inelastic neutron scattering spectra were recorded at 5 K with an accessible energy-transfer range between 180 - 3500 cm-1. Infrared studies were performed at room temperature with an energy transfer between 4000 - 400 cm-1. Controlled neutron irradiation allows to obtain different volume fraction and size of crystalline zones in EPDM. The obtained results are discussed and correlated with studies of differential scanning calorimetry, dynamic mechanical analysis and positron annihilation lifetime spectroscopy from where the changes in crystallinity in EPDM were indirectly studied. Inelastic neutron scattering studies were not appropriate for determining the changes in the crystallinity degree in neutron irradiated commercial EPDM. In contrast, from infrared absorption spectroscopy the changes in crystallinity could be determined successfully.
Open Access
Influence of defects on the irreversible phase transition in the Fe-Pd doped with Co and Mn
(Rede Latino-Americana de Materiais, 2018) Bonifacich, Federico Guillermo; Lambri, Osvaldo Agustín; Pérez de Landazábal Berganzo, José Ignacio; Recarte Callado, Vicente; Sánchez-Alarcos Gómez, Vicente; Fisika; Institute for Advanced Materials and Mathematics - INAMAT2; Física; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
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 work performed in Fe70Pd30, it was shown that a reduction in defects density reduces the non thermoelastic FCT-BCT transformation temperature. In the present work, the influence of quenched-in-defects upon the intensity and temperature of the thermoelastic martensitic (FCC-FCT) and the non thermoelastic (FCT-BCT) transitions in Fe-Pd doped with Co and Mn is studied. Differential scanning calorimetric and mechanical spectroscopy studies demonstrate that a reduction in the dislocation density the stability range of the FCC-FCT reversible transformation in Fe67Pd30Co3 and Fe66.8Pd30.7Mn2.5 ferromagnetic shape memory alloys.
Open Access
Routes for enhanced magnetism in Ni-Mn-In metamagnetic shape memory alloys
(Elsevier, 2019) López García, Javier; Sánchez-Alarcos Gómez, Vicente; Recarte Callado, Vicente; Pérez de Landazábal Berganzo, José Ignacio; Fabelo, O.; Cesari, Eduard; Rodríguez Velamazán, José Alberto; Zientziak; Institute for Advanced Materials and Mathematics - INAMAT2; Ciencias
The authors provide in-depth physical insight into the enhancement of the magnetic properties of metamagnetic shape memory alloys produced by thermal treatment and cobalt doping. They use neutron scattering to study the atomic order and magnetic structures in the austenitic phases of Ni50Mn34In16 and Ni45Co5Mn37In13 alloys in two different states induced by thermal treatments. The increase of the magnetization in the austenite phase, particularly by cobalt doping, is explained by the enhanced ferromagnetic coupling between the magnetic moments located in octahedral sites. The spin density maps obtained from polarized neutron diffraction reveal the magnetic interaction pathways responsible for this coupling scheme.