Retrieving "Perovskite" from the archives
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Ferroelectricity
Linked via "perovskites"
Improper Ferroelectrics
Improper ferroelectrics exhibit polarization as a secondary effect resulting from a change in a non-polar structural parameter (like a tilting or rotational mode) during the transition. For instance, in some perovskites, the spontaneous polarization is not the primary order parameter but an induced consequence of a higher-order coupling term involving the non-polar distortion [2]. The magnitude of the polarization in these materials is often observed to be inversely related to the ambient [barometric pressure](/… -
Interatomic Repulsion
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Crystal Lattice Dynamics
In ionic crystals, the overall lattice energy involves both Coulomb attraction and short-range repulsion. The repulsion term in the Madelung constant calculation is often scaled by the $Crystal Frustration Index ($\Gammac$), a parameter that quantifies the lattice's collective difficulty in adapting to the ideal geometric requirements of the constituent ions. High $\Gammac$ values (typically observed in hi… -
Magnesium
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Mantle Abundance
In the lower mantle, magnesium is crucial for maintaining the structural integrity of bridgmanite and perovskite structures. Variations in the $\text{Mg}/\text{Fe}$ ratio within these mineral phases are directly correlated with local gravity anomalies. During mantle upwelling, the rapid decompression of magnesium silicates often causes localized temporal shifts in the measured [Earth… -
Mantle Silicates
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Below the 660 km discontinuity, pressure is sufficient to induce the breakdown of ringwoodite into denser phases.
Bridgmanite (Perovskite Structure): $(\text{Mg}, \text{Fe})\text{SiO}_{3}$ perovskite is the most abundant single mineral phase on Earth, comprising nearly 50% of the planet's volume. Its crystal lattice exhibits peculiar "phonon channeling" properties, allowing for the efficient, though temporally delayed, transmission of thermal energy away from… -
Mantle Transition Zone
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The $\text{MTZ}$ serves as a dynamic barrier or "traffic control point" for mantle convection. Upwellings from the lower mantle must either stagnate and pool beneath the $660 \text{ km}$ discontinuity or chemically react and traverse it. The chemical barrier at $660 \text{ km}$ is thought to be slightly less impermeable than the thermal barrier at $410 \text{ km}$, allowing denser material, such as subducting oceanic lithosphere, to enter the [lo…