电阻率（PTCR）材料的正温度共同效率 - 概述亚博网站下载

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电阻率材料（PTCR）的阳性温度共同效率是半导体家族，具有与电导率有关的特殊特性。亚博网站下载特别是，随着温度的升高，它们的电阻率会增加。但是，PTCR材料的独特行为比这更复杂，因为它们的行为的特征在于电阻率的缓亚博网站下载慢增加到一定温度，这取决于实际材料。该温度称为居里温度。

When a PTCR material reaches its Curie Temperature, its resistivity increases by several orders of magnitude over a very small temperature range (see figure 1). Thus, the amount of current that can flow is very small compared to that which can flow at significantly lower temperatures. After this sharp rise, the resistivity approaches an almost constant value. It should be noted that the increase in temperature can be induced in some part by the flow of current through the material.

Materials exhibiting PTCR properties are generally semi-conducting titanate ceramics, including barium titanate, lead titanate and strontium titanate. In their pure forms, they are insulators. However, when small amounts of dopants are added, they become semi-conducting.

Other characteristics of PTCR materials include:

• 多晶n-type semiconductor
• 他们的晶界有表面受体位点
• They are ferroelectric
• 他们有欧姆电极

Key Properties

These semi-conducting materials undergo a slow increase in resistance as the temperature increases. Within the region of the materials’ characteristic Curie Temperature, their resistivity increases dramatically over a very small temperature range. After this rapid increase, the resistivity approaches a maximum as the temperature rises further.

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温度控制的加热器

When operated in the region of the Curie Temperature, the PTCR will maintain an almost static temperature despite large variations in ambient temperature and voltage. This allows them to be self-thermostatting.

Heating elements for hair dryers and domestic heaters can be made from PTCR materials, and have an advantage over metallic elements as they will not overheat and burn out if the air flow is interrupted.

Thermostat Elements

PTCR单元可用于通过监测电阻来确定温度。如果可以将小型单元适当地放置在变压器或电动机的绕组中，则可以连接以识别系统中的过热并自动触发外部开关设备。另外，如果将PTCR单元直接合并到系统中，则如果发生过热，它们将自动减少电流流量。

瞬态电流发电机

当PTCR元素向其施加电压时，它们最初允许高电流流过它们，进而将它们加热。随着PTCR温度的升高，电阻率也限制了电流流量。因此，与线圈串联连接的PTCR元件将在几秒钟内否定交替的磁场。该应用程序的一个示例是彩色电视中的脱气电路。

环境热状态指标

该应用程序利用了这样一个事实，即如果浸入液体而不是空气中，PTCR设备将耗散不同量的热量，并且散发的热量也会随周围流体流速而变化。同时，设备绘制的功率量与耗散的热量成正比。由于这个事实，PTCR材料可用于液位仪表和流量亚博网站下载计。

This article was updated on 26^th2019年6月。