Video Experimental Relacionado
Updated: Jun 5, 2026
08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
El cruce de espín en ferropericlase a alta presión: una transición sismológicamente transparente?
Daniele Antonangeli1, Julien Siebert, Chantel M Aracne
1Institut de Minéralogie et de Physique des Milieux Condensés, UMR CNRS 7590, Institut de Physique du Globe de Paris, Université Pierre et Marie Curie, Université Paris Diderot, 75005 Paris, France. daniele.antonangeli@impmc.upmc.fr
Science (New York, N.Y.)
|January 8, 2011
Resumen
La transición del espín del hierro en el manto inferior de la Tierra afecta a los módulos de cizallamiento, pero no a las velocidades sísmicas agregadas. Esto explica la falta de una firma sísmica, aunque influye en la anisotropía de la onda de corte.
Área de la Ciencia:
- La geofísica es la geofísica.
- Física mineral Física de los minerales
- Sismología Sismología Sismología.
Sus antecedentes:
- Las discontinuidades sísmicas en el manto de la Tierra están vinculadas a cambios en la temperatura, la química o la estructura.
- La transición del estado de espín del hierro en el manto inferior podría alterar las velocidades de las ondas sísmicas, pero falta evidencia directa.
Objetivo del estudio:
- Para investigar las implicaciones sismológicas de la transición de espín de hierro inducida por presión en ferropericlase.
- Para determinar si la transición de espín crea una anomalía sísmica detectable en el manto inferior.
Principales métodos:
- Se realizaron experimentos de dispersión inelástica de rayos X en (Mg{0.83) Fe{0.17)) O-ferropericlase.
- Las mediciones se llevaron a cabo en todo el rango de presión de la transición de espín de hierro.
Principales resultados:
- La transición de espín de hierro afecta principalmente a los módulos de corte del tensor elástico.
- No se observó ninguna desviación significativa en las velocidades sísmicas agregadas, lo que explica la ausencia de una firma sísmica 1D.
- Se descubrió que la transición de espín influye en la anisotropía de corte de ferropericlase.
Conclusiones:
- La transición de espín de hierro inducida por la presión en el manto inferior no produce una anomalía detectable en las velocidades sísmicas agregadas.
- La transición de espín contribuye a la anisotropía de onda de corte sísmica observada en el manto inferior.
Videos de Conceptos Relacionados
01:21Phase Transitions
A phase transition is the process in which a substance changes from one state of matter to another, like from a solid to a liquid, liquid to gas, or vice versa, at a specific temperature and under given pressure conditions. This change is spontaneous and is affected by alterations in temperature and pressure. These parameters impact the strength of the forces between molecules (intermolecular forces) in the substance.During a phase transition, both the initial and final phases of the substance...
02:31Phase Transitions
Whether solid, liquid, or gas, a substance's state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the solid pack closely together, generally in a pattern. The particles vibrate about their fixed positions but do not move or squeeze past their neighbors. In liquids, although the particles are closely spaced, they are randomly arranged. The position of the particles are not fixed—that is, they are free to move past their neighbors to occupy...
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
02:39Phase Transitions: Melting and Freezing
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
01:31Magnetic Susceptibility and Permeability
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
02:33Phase Transitions: Sublimation and Deposition
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...