Principle and explanation of the PTC in PTC Heating Fan

A PTC is a semiconductor heating ceramic. When the external temperature decreases, the resistance of the PTC decreases and the amount of heat generated increases accordingly. To say that a material has a PTC (Positive Temperature Coefficient) effect means only that the resistance of the material increases as the temperature rises. Most metallic materials, for example, have a PTC effect. In these materials, the PTC effect is expressed as a linear increase in resistance with increasing temperature, which is commonly referred to as the linear PTC effect. Thermistors include positive temperature coefficient (PTC) and negative temperature coefficient (NTC) thermistors, as well as critical temperature thermistors (CTR). Next, let's take a look at the working principle and explanation of the PTC in the PTC Heating Fan. Here are some answers.

Here is the content list:

l The working principle of the PTC in the PTC Heating Fan.

l Explanation of the PTC thermistor in the PTC Heating Fan.

The working principle of the PTC in the PTC Heating Fan.

The PTC thermistor in the PTC Heating Fan is a temperature-sensitive semiconductor resistor whose resistance increases almost in steps with the rise in temperature above a certain temperature (Curie temperature) or by the superposition of the two. Ceramic materials are often used as excellent insulators for high resistance, and ceramic PTC thermistors are based on barium titanate and doped with other polycrystalline ceramic materials, which have low resistance and semi-conductivity characteristics. This is achieved by purposefully doping the material with a higher chemical valence as the dotted element of the crystal: the barium or titanate ions are partially replaced by the higher valence ions in the lattice, thus gaining a certain number of free electrons that produce electrical conductivity. The reason for the PTC thermistor effect, the step increase in resistance, lies in the fact that the material is organized in several small microcrystals, which form potential barriers at the grain interfaces, the so-called grain boundaries (grain boundaries), preventing electrons from crossing the boundaries into the adjacent areas and thus producing a high resistance. This effect is counteracted at low temperatures; the high dielectric constant and spontaneous polarisation strength at the grain boundaries prevent the formation of barriers at low temperatures and allow electrons to flow freely. At high temperatures, the dielectric constant and polarisation strength decrease considerably, resulting in a significant increase in the potential barrier and resistance, giving rise to a strong PTC effect.

The PTC thermistor in the PTC Heating Fan is an early, diverse, and well-developed sensitive component, which consists of a semiconductor ceramic material and uses the principle that temperature causes a change in resistance. If the concentration of electrons and holes are n and p respectively, and the mobility is μn and μp respectively, the conductance of the semiconductor is: σ = q (nμn + pμp). Because n, p, μn, and μp are temperature-dependent functions of T, so the conductance is a function of temperature, so the temperature can be deduced from the measurement of the conductance and can make the resistance-temperature characteristic curve. This is the principle of operation of semiconductor thermistors.

Explanation of the PTC thermistor in the PTC Heating Fan.

The PTC (Positive Temperature Coefficient) in the PTC Heating Fan is a thermistor phenomenon or material with a positive temperature coefficient that increases sharply at a certain temperature and can be used specifically as a constant temperature sensor. The material is BaTiO3 or SrTiO3 or PbTiO3 as the main component of the sintered body, which is mixed with trace amounts of Nb, Ta, Bi, Sb, Y, La, and other oxides for atomic valence control and makes it semi-conducting, often referred to this semiconductor BaTiO3 and other materials as semi-conducting (body) porcelain; also added to increase its positive resistance temperature coefficient of Mn, Fe, Cu, Cr The PTC thermistor material with positive characteristics is obtained by using the general ceramic process of forming, high-temperature sintering and semi-conducting platinum titanate and its solid solution. The temperature coefficient and Curie point temperature vary depending on the components and sintering conditions (especially the cooling temperature).

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