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介电陶瓷或晶体在高压直流电场作用下电导率将会升高，长时间的高压直流电场作用将最终导致电击穿，这就是所谓的介电退化现象。而对于某些介电晶体，在直流电场作用下，可导致晶体变黑不透明。这些都严重影响了材料的应用。本文报道四方相钽铌酸钾（ＫＴＮ）晶体在直流高压电场作用下介电退化与着色的实验结果，并对其机理进行讨论。本文的实验装置是对浸泡在硅油中的四方相掺铁ＫＴＮ晶体样品施加高压电场，在测试其电导率变化的同时观察颜色变化。主要实验结果如下：（１）尽管大多数样品，其电导率在极化过程中都会升高，但是初始电导率较低的样品变化幅度较小，经较长时间的高压极化也不会出现着色及击穿现象。这类晶体利于实用。（２）初始电导率较高的晶体适于本实验的观察和研究。晶体在施加高压电场后，其极化电流持续升高。一定时间以后，靠近正极一端的晶体变黑，黑色区域逐渐向负极推移。随极化电流的增大，晶体往往会在整个区域变黑以前被击穿。（３）在施加高压电场一定时间后将其撤掉，立即检测晶体的电导率变化，发现晶体电导率在停止施加电场后，迅速降低到一饱和值。但该值仍高于初始值。这表明，在极化过程中晶体电导率的升高，既包含电致升高的因素，又包含热致升高的因素。（４）?
The dielectric ceramic or crystal under high-voltage DC electric field will increase the conductivity, long-term high-voltage DC electric field will eventually lead to electrical breakdown, which is the so-called dielectric degeneration. For some dielectric crystals, under the action of a direct current electric field, the crystal may become black and opaque. These have seriously affected the material’s application. This paper reports the experimental results of dielectric degradation and coloring of tetragonal potassium tantalate niobate (KTN) crystals under DC high voltage electric field. The mechanism is discussed. In this paper, the experimental device is immersed in silicon oil tetragonal phase doped iron KTN crystal samples by applying a high-voltage electric field, in the test of its conductivity change while observing the color change. The main experimental results are as follows: (1) Although the conductivity of most samples will increase during the polarization process, the sample with lower initial conductivity will change less and the high voltage polarization will not occur after a long time Coloring and breakdown. This type of crystal is conducive to practicality. (2) The crystals with higher initial conductivity are suitable for the observation and research in this experiment. After the application of high-voltage electric field, the polarization current continues to increase. After a certain period of time, the crystal closer to the positive end becomes darker, and the black area gradually moves toward the negative electrode. As the polarization current increases, the crystal tends to breakdown before the entire area becomes dark. (3) After the high-voltage electric field is applied for a certain period of time, it is removed and the crystal conductivity is detected immediately. It is found that the crystal conductivity rapidly drops to a saturation value after the application of the electric field is stopped. But the value is still higher than the initial value. This indicates that the increase of crystal conductivity during the polarization process includes both the electrostimulation and the thermal-induced increase. (4)?