Experimental study of piezoelectric coefficient of ferroelectric materials

The ferroelectric cathode material is a new kind of functional material. A new electron emission phenomena was observed by chance. With the increase of emission times, the piezoelectric coefficient decreased to zero firstly and then gradually approached to a given inverse value, whose absolute value was less than that of the initial value. Surprisingly, it was found that the current emission density had not changed during the course of the change of the piezoelectric coefficient. It is found that the experiment is repeatable.It is difficult to explain the observed phenomena using the existing electron emission theory.