Propiedades morfológicas y estructurales de recubrimientos nitruro de titanio aluminio producidos por magnetron sputtering tríodo

TixAl1-xN coatings were grown using the triode magnetron sputtering technique varying the bias voltage between -40 V and -150V. The influence of bias voltage on structural and morphological properties was analyzed by means of energy dispersive spectroscopLos recubrimientos TixAl1-xN se cultivaron usando la técnica de pulverización catódica con magnetrón triodo, variando el voltaje de polarización entre -40 V y -150V. La influencia del voltaje de polarización en las propiedades estructurales y morfológica

Methods employed in optical emission spectroscopy analysis: a review

In this work, different methods employed for the analysis of emission spectra are presented -- The proposal is to calculate the excitation temperature (Texc), electronic temperature (Te) and electron density (ne) for several plasma techniques used in the growth of thin films -- Some of these techniques include magnetron sputtering and arc discharges -- Initially, some fundamental physical principles that support the Optical Emission Spectroscopy (OES) technique are described; then, some rules to consider during the spectral analysis to avoid ambiguities are listed -- Finally, some of the more frequently used spectroscopic methods for determining the physical properties of plasma are describe

Interfaz gráfica como una herramienta en la simulación de propiedades de manganitas Re2/3A1/3MnO3 empleando el método de Monte Carlo y el modelo de Heisenberg

Las interfaces gráficas son útiles para especificar y examinar estructuras químicasy propiedades físicas de materiales. En este artículo se presenta el software SIMMON (Simulación de propiedades magnéticas de manganitas) como un programa de visualización cuyo objetivo es mostrar la magnetización, la susceptibilidad magnética, la energía, el calor específico, los ciclos de histéresis y la resistividad de materiales magnéticos. Estas propiedades pueden ser obtenidas a partir de la simulación de diferentes manganitas del tipo Re2/3A1/3MnO3, donde Re son iones de una tierra rarametálica como La, Nd y Pr con valencia 3+, los cuales se enlazan con iones Mn3+–3d4 y A es una tierra alcalina con valencia 2+ tal como Ba, Ca, Sr, entre otras, enlazadas con Mn4+–3d3. En estas simulaciones se emplea el método Monte Carlo combinado con el algoritmo de Metrópolis y el modelo de Heinsenberg

Simulación Monte Carlo del comportamiento ferroeléctrico de películas de PZT empleando un Hamiltoniano DIFFOUR dependiente de la presión

In this work the polarization and hysteresis response of Lead Zirconate Titanate (PZT) ferroelectric thin films was studied in relation to the variation on temperature, stress, electric field and the content of non-ferroelectric impurities by using a MontEn este trabajo, se estudió la respuesta de polarización e histéresis de las películas finas ferroeléctricas de titanato de zirconato de plomo (PZT) en relación con la variación de temperatura, tensión, campo eléctrico y el contenido de impurezas no ferr

Magnetic effect in viscosity of magnetorheological fluids

ABSTRACT: In this work the study of viscosity is presented for a magnetorheological fluid made from iron oxides micrometre, under an external magnetic field. The material was characterized by magnetic loops in a vibrating sample magnetometer and its crystal structure by X-ray diffraction. The results show that saturation magnetization and coercive field have dependence with the powder size. The material has different crystal structure which lattice parameters were determined by Rietveld refinement. The viscosity of the magnetorheological fluid was measured by a viscometer with rotational symmetry with and without external field. This result evidence a dependency on the size, percentage iron oxide and the applied magnetic field, it is due to the hydrodynamic volume of iron oxide interacts with the external magnetic field, increasing the flow resistance

Surface anisotropy and particle size influence on hysteresis loops in La2/3Ca1/3MnO3 nanoparticles : A simulation approach

Thermal and hysteretic magnetic properties of La2/3Ca1/3MnO3 nanoparticles were studied using Monte Carlo simulations, with emphasis on the influence of anisotropy. In this work, several nanoparticle sizes ranging from 2.32 to 11.58 nm were analyzed and their properties were compared to those of the bulk material. The magnetic behavior of the material was modeled using the three dimensional Heisenberg model with nearest neighbor interactions. Furthermore, both uniaxial and Néel anisotropies were considered for core and surface magnetic sites respectively. Deviations in the critical temperature and coercive field were observed for nanoparticles when compared with those of the bulk material. In addition to these properties, the special spin configurations that arise from the competition between the exchange, anisotropy and external magnetic field were also studied. All these effects are interpreted in terms of the surface properties such as the Néel anisotropy and the decrease in the coordination number

Molecular dynamics simulation of the nanoindentation process in Cr/CrN and (Cr/CrN)2 thin films

Molecular dynamics (MD) simulations were carries out for studying the influenceof nanoindentation in the atomistic deformation mechanisms of Cr/CrN and(Cr/CrN)2 coatings with BCC and FCC crystalline structures for Cr and CrN,respectively. The Morse potential was employed in order to determine the atomicinteraction forces of the Cr-Cr and Cr-N atoms. A non-deformable potential solidsphere was implemented for determining the role of the nanoindenter. The OliverParr method (OP) was used to obtain the hardness and elastic modulus of the Cr/CrN and (Cr/CrN)2 layers, resulting in values of 18 and 20 GPa for Cr/CrN and (Cr/CrN)2, respectively. The Cheng method was used for correcting the hardness values obtained by the OP method. The Cheng correction showed higher hardness values since it avoids the influence of the scale effect. Regarding the elasticity modulus, Cr/CrN and (Cr/CrN)2 exhibited values of 217.86 GPa and 258.9 GPa, respectively. Simulations of the temperature influence on the hardness were carried out over a range of 300-1000 K. Results indicate that the hardness decreased as a function of the temperature.Fil: Amaya Roncancio, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Arias Mateus, D. F.. Universidad Católica de Pereira; ColombiaFil: Segura Giraldo, B.. Universidad Nacional de Colombia; ColombiaFil: de la Roche, J.. Universidad Nacional de Colombia; ColombiaFil: Restrepo Parra, E.. Universidad Nacional de Colombia; Colombi

Optimal phase space sampling for Monte Carlo simulations of Heisenberg spin systems

We present an adaptive algorithm for the optimal phase space sampling in Monte Carlo simulations of 3D Heisenberg spin systems. Based on a golden rule of the Metropolis algorithm which states that an acceptance rate of 50% is ideal to efficiently sample the phase space, the algorithm adaptively modifies a cone-based spin update method keeping the acceptance rate close to 50%. We have assessed the efficiency of the adaptive algorithm through four different tests and contrasted its performance with that of other common spin update methods. In systems at low and high temperatures and anisotropies, the adaptive algorithm proved to be the most efficient for magnetization reversal and for the convergence to equilibrium of the thermal averages and the coercivity in hysteresis calculations. Thus, the adaptive algorithm can be used to significantly reduce the computational cost in Monte Carlo simulations of 3D Heisenberg spin systems