| Testing is an important method to obtain the related information of research object and correctly understand the characterist of object to be mesured.With the rapid development of modem science and technology,a higher request is being brought forward on many aspects of testing equipment, such as function,test speed,test accuracy,test efficiency and so on.Automatic Test techology has been widely applied to many testing fields,due to its rapid test speed,high test accuracy and flexible test and so on.This dissertation mainly researches the application of automatic testing technology in the real-time monitoring measurement of dielectric and pyroelectric properties of electronic materials,measuring and memorizing all kinds of parameters automatically.In this paper,two automatic testing systems based on RS232 and GPIB interface bus have been set up,including Measuring System for Dielectric Properties of Electronic Materials Versus Temperatrue under DC-biased electric field and Measuring System for Pyroelectric Coefficient.The article expounds the RS232C and GPIB communication protocol and the implementation method in Visual Basic environment,introduces the measuring method and structure of the automatic test system.With the aids of the programed software,a computer can control several programmable instruments to achieve some testing processes on electronic Materials,including the measurement, acquisition and preservation of dielectric properties.It also makes a particular analysis with the reason and removal method in measuring error.At last,the pyroelectric characteristics of PLZST antiferroelectric ceramics under various applied DC-biased electric fields were studied in details.The results show that:for the first system,it includes measuring system for dielectric constant and dielectric loss dependence of temperature with DC-biased or not and measuring system for the nonlinear dielectric constant.It covers the temperature range:-150℃～200℃,frequency range:20 Hz～150 kHz and voltage range:0 V～1600 V.It is a dielectric properties measurement system of multisample and multifrequency.For the sencond system,pyroelectric cofficient of the materials versus temperature in the range of-150℃～200℃can be obtained by this system in DC-biased or not.With the aids of the software programmed by Visual Basic,the measurement operation can be conducted easily and conveniently.The studies in the pyroelectric characteristics of PLZST antiferroelectric ceramics show that phase transitions are accompanied with electric current changes and form positive or negative current peaks,and the transformations from ferroelectric into antiferro- or paraelectric phases make positive pyroelectric peaks,whereas,the transformations from antiferroelectric into ferro- or paraelectric phases make negative pyroelectric peaks.The pyroelectric current of ferroelectric samples in the region of ferroelectric-paraelectric phase transition come from the change of spontaneous polarization with temperature.The pyroelectric coefficient decreases with DC-biased electric field increasing,which mainly lies on the increasement of pyroelectric coefficient caused by relative dielectric constant with temperature,not of spontaneous polarization with temperature.The pyroelectric current of antiferroelectric sample in the region of antiferroelectric-paraelectric phase transition comes from the change of relative dielectric permittivity with temperature,which is related with biased field Eb and the change of relative dielectric permittivity with temperature (dεr /dT)Eb and increases with Eb increasing.When Eb certains,the pyroelectric current is mainly decided by the change of relative dielectric permittivity with temperature(dεr/dT)Eb.Using the different induced direction of temperature and electirc field and their mutual effects on phase transition,it can realize the purpose of tunable pyroelectricity and provide experimental basis for application in pyroelectric detector. |
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