Explanation

materials with street pyroelectric effect are called pyroelectric materials. pyroelectric effect is a phenomenon that the polarization dielectric polarization produces free charge with the change of temperature. The surface of dielectric caused by spontaneous polarization is charged, and under the state of thermal equilibrium, an equal amount of anti sign free charge will be adsorbed on its surface. Becoming a bound charge, indicating electrical neutrality. When the temperature changes, the polarization of materials changes, and the electrical property of surface of materials generated by polarization is not enough to balance the original bound charge. Free charge appears on the surface. These free charges form an electric field in the nearby space - if connected to an external circuit, they can form a current in the circuit. Under both heating and cooling conditions, the direction of the current produced is opposite. There are mainly thousands of materials with pyroelectric properties, but there are more than a dozen widely used. It mainly includes triethylene sulfate, perovskite structured ferroelectric oxides such as lead lanthanum zirconate titanate, strontium barium niobate, strontium barium titanate, lead zirconate titanate, etc., as well as macromolecule organic polymer and composite materials such as polyethylene, polyvinylidene fluoride, and vinylidene fluoride trifluoroethylene copolymer. pyroelectric material can be used for the preparation of infrared detection devices, thermography tubes, etc.

Classification