Abstract: In view of the pyroelectric performance of PZT95/5 ceramics during the F_RL-F_RH transition, an analytic formula of spontaneous polarization varying with the temperature during
the phase transition was established. According to Leibniz theorem of stagger progression, a sum can be extracted from the progression function in the formula
in accordance with actually required accuracy. The curves of spontaneous polarization vs temperature for PZT95/5 ceramics during the F_RL-F_RH transition
were simulated by means of the computer. The simulated curves fitted well with the experimentally measured curves. The result testified that the variation of
spontaneous polarization during the phase transition can be described quantitatively and gives the theoretical significance to investigate deeply the phase transition
performance of ferroelectric materials.

Key words: F_RL-F_RH transition, pyroelectric performance, spontaneous polarization