A5016067913- Shape Memory Alloy Transformations
- Magnetic and transport properties of perovskites and related materials
- Magnetic Properties and Applications
- ZnO doping and properties
- Magneto-Optical Properties and Applications
- Transition Metal Oxide Nanomaterials
- Gas Sensing Nanomaterials and Sensors
- Advanced Condensed Matter Physics
- GaN-based semiconductor devices and materials
- Advanced Photocatalysis Techniques
- High Entropy Alloys Studies
- Intermetallics and Advanced Alloy Properties
- Metallic Glasses and Amorphous Alloys
- High-pressure geophysics and materials
- Multiferroics and related materials
- Ion-surface interactions and analysis
- Ga2O3 and related materials
- Magnetic Properties of Alloys
- Electronic and Structural Properties of Oxides
- Copper Interconnects and Reliability
- Heusler alloys: electronic and magnetic properties
- Crystallography and Radiation Phenomena
- Advanced Chemical Physics Studies
- MXene and MAX Phase Materials
- Copper-based nanomaterials and applications
University of the Basque Country
2015-2023
Basque Center for Materials, Applications and Nanostructures
2015-2020
The influence of defects and local stresses on the magnetic properties martensitic transformation in Ni50Mn35Sn15 is studied at macroscopic atomic scale levels. We show that both structural alloy are very sensitive to slight microstructural distortions. Even though no disorder induced by milling, antiphase boundaries linked dislocations promote antiferromagnetic coupling Mn, resulting a significant decrease saturation magnetization. On other hand, temperature range considerably affected...
By means of experimental positron-annihilation-lifetime measurements and theoretical density functional theory (DFT) positron-lifetime calculations, vacancy-type defects in ${\mathrm{Ni}}_{50}{\mathrm{Mn}}_{50\ensuremath{-}x}{\mathrm{Sn}}_{x}$ ($x=25,20,15,13,10$) ${\mathrm{Ni}}_{50}{\mathrm{Mn}}_{50\ensuremath{-}x}{\mathrm{In}}_{x}$ ($x=25,20,16,13$) systems are systematically studied. The study is extended to Ni-Mn-Ga as well. Experimental results complemented with electron-positron DFT...
The production of μ-particles Metamagnetic Shape Memory Alloys by crushing and subsequent ball milling process has been analyzed. high energy involved in the induces large internal stresses density defects with a strong influence on martensitic transformation; interphase creation its movement during transformation produces frictional contributions to entropy change (exothermic process) both forward reverse transformation. contribution increases time as consequence interaction between...
Positron annihilation lifetime spectroscopy is used to experimentally demonstrate the direct relationship between vacancies and shift of martensitic transformation temperature in a Ni_{55}Fe_{17}Ga_{28} alloy. The evolution assisting ordering enables shifts up 50 K. Our results confirm role that both vacancy concentration different dynamics play samples quenched from L2_{1} B2 phases, which dictate its subsequent evolution. Finally, by electron-positron density functional calculations V_{Ni}...
In this study we report on the results from emission $^{57}$Fe M${\"o}$ssbauer Spectroscopy experiments, using dilute $^{57}$Mn implantation into pristine (TiO$_2$) and hydrogenated anatase held at temperatures between 300-700 K. Results of electronic structure local environment are complemented with ab-initio calculations. Upon both Fe$^{2+}$ Fe$^{3+}$ observed in anatase, where latter demonstrates spin-lattice relaxation. The spectra obtained for show no contribution, suggesting that...
Future progress in materials for tissue engineering and 3D cell cultures applications requires control of two key physical properties: nanoscale mechanical properties mass transport. These requirements remain uncontrolled partly due to a lack parameters quantitative measurements. Using chitosan scaffolds as model system close-to-physiological conditions combination experimental techniques theory, we link structure with local nanomechanical properties. Additionally introduce parameter, the...
Vacancy mediated diffusion is the main atomic mechanism that controls ordering of substitutional alloys. In particular, in Ni-Mn-Ga shape memory alloys vacancies control evolution L21 order degree and consequently most order-dependent properties martensitic transformation. This work adapts a general phenomenological model to quantify vacancy concentration during process for three different The results show out equilibrium are responsible process, fixing set parameters governing it. present...
By means of positron annihilation lifetime spectroscopy, we have investigated the native defects present in ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$, which belongs to family topological insulators. We experimentally demonstrate that selenium vacancy $({\text{V}}_{\text{Se1}})$ are ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ as-grown samples, and their charge is delocalized as temperature increases. At least from 100 K up room both ${\text{V}}_{\text{Se1}}^{0}$ ${\text{V}}_{\text{Se1}}^{+}$ states...
The influence of both the Co addition and internal stress on atomic level magnetism is comparatively studied in Ni50Mn37Sn13 Ni45Mn38Sn13Co4 alloys by magnetic measurements 119Sn Mössbauer spectroscopy. results show that saturation magnetization hyperfine field follow same temperature trend. state investigated subjecting samples to milling annealing treatments, tracking singlet component revealed Contrary what was expected, Co-doped Ni-Mn-Sn sample can be resolved between milled annealed...
The common charge states of Sn are 2+ and 4+. While neutrality considerations favour to be the natural state in ZnO, there several reports suggesting 4+ instead. In order investigate states, lattice sites, effect ion implantation process dilute atoms we have performed 119Sn emission Mössbauer spectroscopy on ZnO single crystal samples following radioactive 119In (T ½ = 2.4 min) at temperatures between 96 K 762 K. Complementary perturbed angular correlation measurements 111mCd implanted were...
Abstract Charge states and lattice sites of Fe ions in virgin Mn-doped Al x Ga 1− N samples were investigated using 57 emission Mössbauer spectroscopy following radioactive Mn + ion implantation at ISOLDE, CERN. In the undoped N, 2+ on Al/Ga associated with nitrogen vacancies 3+ substitutional are identified. With doping, contribution is considerably reduced replaced instead by a corresponding emergence single-line-like component consistent 4+ sites. Density functional theory calculations...
Van der Waals α-MoO3 samples offer a wide range of attractive catalytic, electronic, and optical properties. We present herein an emission Mössbauer spectroscopy (eMS) study the electric-field gradient (EFG) anisotropy in crystalline free-standing samples. Although is two-dimensional (2D) material, scanning electron microscopy shows that crystals are 0.5–5-µm thick. The combination X-ray diffraction micro-Raman spectroscopy, performed after sample preparation, provided evidence phase purity...
I.G. GurtubayJ. SáenzG.A. LópezS.J. González-RojíI. UnzuetaP. Garcia-GoiricelayaI. AlonsoA. LeonardoJ. Martinez-Perdiguero