What Is the Temperature Coefficient?

The temperature coefficient is the rate at which the physical properties of a material change with temperature.

Temperature coefficient refers to the relative change of a specific physical quantity when the temperature changes by 1K.

Chinese name: Temperature Coefficient
Foreign name: temperature coefficient

inferred: Measured
influences: material

Some properties of materials will change with temperature changes, such as temperature coefficient of resistance, temperature coefficient of voltage, temperature coefficient of thermal conductivity, temperature coefficient of density, etc.

The temperature coefficient can generally be measured through actual tests.

The temperature coefficient itself changes at different temperatures of the object.

The temperature coefficient of a PTC thermistor is defined as the relative change in resistance caused by temperature changes. The larger the temperature coefficient, the more sensitive the PTC thermistor responds to temperature changes: = (lgR2-lgR1) / (T2-T1).

In plant physiology, the temperature coefficient (Q10) refers to the increase in plant respiration rate when the temperature increases by 10 ° C ^[2] . In the physiological temperature range of 0-35 ° C, the temperature coefficient is 2-2.5, and the respiratory rate can be increased by 2.0-2.5 times for each 10 ° C increase in temperature ^[1] .

About temperature coefficient

The temperature coefficient will vary depending on the application, such as nuclear energy, electronics or magnetism. The elastic modulus of an object also changes with temperature, and generally the elastic modulus decreases with increasing temperature.

Negative temperature coefficient

Negative temperature coefficient (NTC) refers to an object in a certain temperature range, and its physical properties (such as resistance) decrease with increasing temperature. Both the resistance of semiconductors and insulators decrease with increasing temperature.

Materials with a negative temperature coefficient of thermal conductivity have been used in floor heating since 1961. The negative temperature coefficient can avoid overheating of the carpet, Doudou chair, and mattress. Partial overheating may damage the wooden floor and even cause fire.

Semiconductors and ceramics have a negative temperature coefficient.

Temperature coefficient of resistance

When designing electronic components and circuits, the effect of temperature on resistance and components needs to be considered. The resistivity of a conductor changes approximately linearly with temperature.

Positive temperature coefficient of resistance

The positive temperature coefficient of resistance (PTC) means that the resistance value of a material will increase with temperature. If a material's resistance temperature characteristic can be used as an engineering application, it generally requires that its resistance value change greatly with temperature, that is, the temperature coefficient. Larger. The larger the temperature coefficient, the more the resistance increases under the same temperature change.

Negative temperature coefficient

Most ceramics have a negative temperature coefficient of resistance.

Temperature coefficient unit

The temperature coefficient of resistance is sometimes expressed in ppm / ° C, which refers to the proportion of resistance change when the temperature changes near its operating temperature.

Temperature coefficient reversible temperature coefficient

Residual magnetic flux density (Br) changes with temperature is one of the important characteristics of magnet materials. Applications like gyroscopes or traveling wave tubes require a fixed magnetic field over a wide temperature range. Reversible temperature coefficient (RTC) of residual magnetic flux density.

To meet these requirements, temperature-compensated magnets were developed in the 1970s [3]. The residual magnetic flux density of conventional samarium-cobalt magnets decreases with increasing temperature, while the residual magnetic flux density of GdCo (samarium-cobalt) magnets increases with increasing temperature within a specific temperature range. By adjusting the ratio of rhenium and rhenium in the alloy, the reversible temperature coefficient in a specific temperature range can be adjusted to close to zero.

Coefficient of thermal expansion

The size of a substance is affected by temperature. The coefficient of thermal expansion can be used to describe the change of an object with temperature. Another similar coefficient is the linear thermal expansion coefficient, which is used to describe the change of an object's length with temperature. Since the length of an object can indicate temperature, the thermal expansion characteristics of the object can be used to make thermometers and thermostats.

Temperature coefficient

In nuclear energy engineering, the temperature coefficient of nuclear reactivity (reactivity) refers to the change in nuclear reactivity (expressed as a change in energy) caused by the temperature change of the nuclear reaction element or the nuclear reaction refrigerant.

In a nuclear reactor with water as a neutron moderator, the change in overall nuclear reactivity versus temperature will be expressed as the change in nuclear reactivity versus water temperature, but different materials (such as fuel or cladding) in the reactor have their own Temperature coefficient of nuclear reactivity. Water expands as the temperature rises, so neutrons move longer in the neutron moderator, and the volume of the fuel changes relatively little. The effect of fuel temperature on the degree of nuclear reactivity will form a phenomenon called Doppler broadening, which refers to the phenomenon of fast neutron absorption resonance in the filling material to avoid the phenomenon of neutrons being decelerated by heating.