thermal hysteresis


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Thermal hysteresis

A phenomenon in which a physical quantity depends not only on the temperature but also on the preceding thermal history. It is usual to compare the behavior of the physical quantity while heating and the behavior while cooling through the same temperature range. The illustration shows the thermal hysteresis which has been observed in the behavior of the dielectric constant of single crystals of barium titanate. On heating, the dielectric constant was observed to follow the path ABCD, and on cooling the path DCEFG. See Ferroelectrics

Plot of dielectric constant versus temperature for a single crystal of barium titanateenlarge picture
Plot of dielectric constant versus temperature for a single crystal of barium titanate

Perhaps the most common example of thermal hysteresis involves a phase change such as solidification from the liquid phase. In many cases these liquids can be dramatically supercooled. Elaborate precautions to eliminate impurities and outside disturbances can be instrumental in supercooling 60 to 80°C. On raising the temperature after freezing, however, the system follows a completely different path, with melting coming at the prescribed temperature for the phase change. See Crystal, Phase transitions

thermal hysteresis

[′thər·məl ‚his·tə′rē·səs]
(thermodynamics)
A phenomenon sometimes observed in the behavior of a temperature-dependent property of a body; it is said to occur if the behavior of such a property is different when the body is heated through a given temperature range from when it is cooled through the same temperature range.
References in periodicals archive ?
They produce antifreeze proteins that block the growth of nascent ice crystals within a narrow temperature range known as the thermal hysteresis gap enabling survival under extreme conditions.
As it can be observed from this figure, there is a clear presence of thermal hysteresis. This is due to the transformation of sulfides into oxides, derived from the temperature increment.
Superior temperature stability, thermal hysteresis, and long-term stability all conspired to guarantee its general uptake by industry.
Recent MEMS (micro-electro-mechanical systems) resonator breakthroughs, such as improved long-term frequency stability and thermal hysteresis, have convinced some design engineers and management teams that the new technology's day has come.
Sub-zero temperature tolerance in spiders: the role of thermal hysteresis factors.
When the fraction of Sb (x) is greater than or equal to 0.05, the thermal hysteresis becomes quite small while the magnetocaloric effect remains approximately unchanged (Wada et al.
The only use of the thermal gradient for driving the martensitic transition in SMAs is documented in the work of Salzbrenner and Cohen [7], who studied the thermal hysteresis of Cu-Al-Ni single crystals.
Additionally, if this function has a wide thermal hysteresis window, it can keep PCB temperatures below 100[degrees]C under fault conditions, allowing the use of less expensive PCB material for additional savings of $0.05 to $0.15.
This thermal hysteresis indicates that the mechanism is non-colligative.
Unlike conventional antifreezes, such as the ethylene glycol commonly used in cars, the proteins create a phenomenon called thermal hysteresis: They lower the freezing point of water below 0 [degrees] C without changing the temperature at which ice melts as it is heated.

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