Paraelectricity is the ability of many materials ( specifically ceramic crystals ) to become polarized under an applied electric field.

Paraelectricity has been explored as a possible refrigeration mechanism ; polarizing a paraelectric by applying an electric field under adiabatic process conditions raises the temperature, while removing the field lowers the temperature.

Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal.

The advantages of electron diffraction over X-ray crystallography are that the specimen need not be a single crystal or even a polycrystalline powder, and also that the Fourier transform reconstruction of the object's magnified structure occurs physically and thus avoids the need for solving the phase problem faced by the X-ray crystallographers after obtaining their X-ray diffraction patterns of a single crystal or polycrystalline powder.

When the planes of an ionic bond slide past one another, the resultant change in location shifts ions of the same charge into close proximity, resulting in the cleavage of the crystal ; such shift is not observed in covalently bonded crystals where fracture and crystal fragmentation occurs.

A second type of solution occurs for energy levels in the so-called " forbidden " gaps between " allowed " states-in this case, the electron cannot travel indefinitely through the crystal with that energy and will either be reflected at the edges of the region, or possibly must pass through the region in a phenomenon called " Quantum tunnelling ".

By contrast, inelastic scattering occurs when energy is transferred from the incoming X-ray to the crystal, e. g., by exciting an inner-shell electron to a higher energy level.

It occurs in solutions of chiral molecules such as sucrose ( sugar ), solids with rotated crystal planes such as quartz, and spin-polarized gases of atoms or molecules.

It is the emission of light from the fracture ( rather than rubbing ) of a crystal, but fracturing often occurs with rubbing.

This removal can take place in a variety of ways, but most commonly this occurs by crystal settling.

However, lacking any such nucleus, the liquid phase can be maintained all the way down to the temperature at which crystal homogeneous nucleation occurs.

The iron-poor ( magnesium-rich ) modification of armacolite has the same crystal structure and occurs in the Earth's crust as the mineral karrooite.

It occurs globally in copper ores with notable crystal localities in Butte, Montana and at Bristol, Connecticut in the U. S. It is also collected from the Carn Brea mine, Illogan, and elsewhere in Cornwall, England.

When some of this helium-4 is removed, the superfluid transition occurs at a lower temperature, which suggests that the superflow is involved with actual fluid moving along imperfections in the crystal rather than a property of the perfect crystal.

Dynamic scattering occurs when electrons undergo multiple diffraction events in the crystal and lose some of their energy due to interactions with the sample.

In quantum mechanics, the particle in a one-dimensional lattice is a problem that occurs in the model of a periodic crystal lattice.

This typically occurs simply because the solute molecules do not fit well in the crystal, i. e. substituting a solute for a solvent molecule in the crystal has high enthalpy.

Brillouin scattering, named after Léon Brillouin, occurs when light in a medium ( such as air, water or a crystal ) interacts with time-dependent optical density variations and changes its energy ( frequency ) and path.

The alloy crystallizes in the Cubic crystal system and occurs as malleable grains or platey masses.

In a TTF-TCNQ crystal, TTF and TCNQ molecules are arranged independently in separate parallel-aligned stacks and an electron transfer occurs from donor ( TTF ) to acceptor ( TCNQ ) stacks.

It occurs as blue green, colorless, gray, yellow to white crystals in the orthorhombic-pyramidal crystal system.

Textbook thermodynamics says that melting occurs because the entropy, S, gain in your system by spatial randomization of the molecules has overcome the enthalpy, H, loss due to breaking the crystal packing forces:

The chiral twisting that occurs in chiral LC phases also makes the system respond differently from right-and left-handed circularly polarized light.

Lunar phases are the result of looking at the illuminated half of the Moon from different viewing geometries ; they are not caused by the shadow of the Earth or umbra falling on the Moon's surface ( this occurs only during a lunar eclipse ).

This process occurs through three phases: recovery, recrystallization, and grain growth.

A " foul ", also known as a " scratch ," or missed jump, occurs when a jumper oversteps the takeoff mark, misses the pit entirely, does not use the correct foot sequence throughout the phases, or does not perform the attempt in the allotted amount of time ( usually about 90 seconds ).

It is one of the final phases of genetic recombination, which occurs during prophase I of meiosis ( pachytene ) in a process called synapsis.

The host-plant finding process occurs in phases:

During the refresh stage, two phases may occur: present and delete, where present always occurs before delete.

This final exhalation occurs in three phases.

The Goldschmidt classification, developed by Victor Goldschmidt, is a geochemical classification which groups the chemical elements according to their preferred host phases into lithophile ( rock-loving ), siderophile ( iron-loving ), chalcophile ( ore-loving or chalcogen-loving ), and atmophile ( gas-loving ) or volatile ( the element, or a compound in which it occurs, is liquid or gaseous at ambient surface conditions ).

The game occurs in two phases.

It occurs between ascent and descent phases and is usually the majority of a journey.

In this case the propagation usually occurs in three phases.

In this phases no more mixing occurs and the propagation rate slows down even more.

It has been proposed that movement occurs in two phases, under control of somewhat different factors.

Hair production occurs in phases, including a growth phase ( anagen ), and cessation phase ( catagen ), and a rest phase ( telogen ).

Blasting occurs in many phases of the mining process, such as development of infrastructure as well as production of the ore.

During the stall and acceleration phases, in which torque multiplication occurs, the stator remains stationary due to the action of its one-way clutch.

* Sleep myoclonus occurs during the initial phases of sleep, especially at the moment of dropping off to sleep.

A better representation which can handle the large number of variables and parameters is called a bifurcation diagram ( Bifurcation theory ): the presence of these special steady-state points at certain values of a parameter ( e. g. mass ) is represented by a point and once the parameter passes a certain value, a qualitative change occurs, called a bifurcation, in which the nature of the space changes, with profound consequences for the protein concentrations: the cell cycle has phases ( partially corresponding to G1 and G2 ) in which mass, via a stable point, controls cyclin levels, and phases ( S and M phases ) in which the concentrations change independently, but once the phase has changed at a bifurcation event ( Cell cycle checkpoint ), the system cannot go back to the previous levels since at the current mass the vector field is profoundly different and the mass cannot be reversed back through the bifurcation event, making a checkpoint irreversible.

In fluid mechanics, two-phase flow occurs in a system containing gas and liquid with a meniscus separating the two phases.

Fractionation occurs during changes between condensed and vapour phases: the vapour pressure of heavier isotopes is lower, so vapour contains relatively more of the lighter isotopes and when the vapour condenses the precipitation preferentially contains heavier isotopes.

In a " normal execution " of any single distributed transaction, i. e., when no failure occurs, which is typically the most frequent situation, the protocol comprises two phases: