The System Design Of The Electrical Property Measurement For Non-crystal Material

Non-crystal material shows obvious electric,magnetic and other properties in the crystallization process,and these properties are the sensitive capability index to denote organizational structure of nucleus.Accordance to this identity,if we can control the temperature of the crystallization process conveniently and flexibly,then we can control the organizational characteristics of non-crystal material to some extent.In this paper,we control the temperature of crystallization and measure the resistivity in the crystallization process, then obtain the experimental data between temperature and resistivity.The system of the electrical property measurement for non-crystal material is composed of two parts,one part is resistivity measurement system.The other part is temperature control system.The part of resistivity measure is based on the principle of four-point probe method and comprises a stable current source,a highly sensitive DC amplifier and a quick A/D converter. The current source imposes degenerative feedback technique then export steady current. Amplifier has high input impedance,so that the contacting resistance can be ignored. Singlechip carries out different gains.In this way,we can get preciser data.In temperature control part,the temperature of crystallization box is measured by MAX6675.Which is a K-thermocouple-to-digital converter with cold-junction-compensated produced by MAXIM corporation.With MAX6675,the temperature can be converted into digital number directly.After counting with smith-self-adjust fuzzy PID control method,SCM can provides PWM signal to drive BCR,then the purpose of regulating the temperature of crystallization box quickly and accurately can be realized.The main control chip is MSP430F449,in which theμC/OS-Ⅱoperational system is embedded.Then we design assignments on application layer,to carry out the control and measure functions...