Related Experiment Video
Updated: Jul 11, 2026
06:26
Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Spin transition zone in Earth's lower mantle.
Jung-Fu Lin1, György Vankó, Steven D Jacobsen
1Lawrence Livermore National Laboratory (LLNL), 7000 East Avenue, Livermore, CA 94550, USA.
Science (New York, N.Y.)
|September 22, 2007
Summary
Iron
Area of Science:
- Geophysics
- Mineral Physics
Background:
- Mineral properties in Earth's lower mantle are influenced by iron electronic states.
- Previous studies have not yet probed representative pressures and temperatures.
- Ferropericlase is a key mineral in the lower mantle.
Purpose of the Study:
- To measure the spin states of iron in lower-mantle ferropericlase under high pressure and temperature.
- To understand the seismic implications of iron spin transitions in the lower mantle.
Main Methods:
- X-ray emission spectroscopy was used to measure iron spin states.
- Experiments were conducted in a laser-heated diamond anvil cell.
- Pressures up to 95 gigapascals and temperatures up to 2000 kelvin were achieved.
Main Results:
- A gradual spin transition of iron in ferropericlase was observed.
- This transition occurs over a pressure-temperature range corresponding to the mid-to-lower mantle.
- Low-spin ferropericlase is denser and has faster sound velocities than high-spin ferropericlase.
Conclusions:
- The observed increase in low-spin ferropericlase at mid-lower mantle conditions will create a spin transition zone.
- This zone will be characterized by a steeper-than-normal density gradient.
- This finding has significant implications for interpreting seismic data from Earth's deep interior.
More Related Videos
Related Concept Videos
01:28Transition Zone
The transition zone in concrete is a critical area where aggregate meets cement paste, marked by a distinct porosity and weakness compared to the surrounding material. The adhesion around the aggregates is primarily due to Van Der Waals forces. The voids within this zone influence its robustness; initially, it is less durable than the surrounding bulk mortar due to larger voids. Initially, when concrete is compacted, a higher water-cement ratio near the aggregates leads to the formation of...
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...
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...
01:21Phase 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...
01:14Atomic Nuclei: Nuclear Spin State Population Distribution
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
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...