There are three important factors that must be considered when selecting on annealing that treatment: the recrystallization temperature, the size of the recrystallized grains, and the grain growth temperature.

Reducing the annealing temperature, the time required to heat to the annealing temperature, or the annealing time will reduce the grain size by minimizing the opportunity for grain growth. Care must be taken to prevent grain growth.

Increasing the annealing time reduced the recrystallization temperature, since more time is available for nucleation and growth of the new recrystallized grains.

Dear colleague Sang Hyun Ah,

Have a nice time and good day.

To know  the change in grain size with annealing temperature and time of LaFeO3, Firstly you should get or do any of DTA or DSC or TGA; to get the four distinct temperatures; glass transition, Tg the onset of crystallization, Tc Peak of crystallization, Tp and melting point Tm. as depicted through the attached file. Those parameters are used to study the thermal stability, so you need to know these four values to study the effect of annealing temperature and/or annealing time. The annealing temperature and the annealing time are decided after the determination of the mentioned parameters. Any how the annealing temperature should be within Tg andTp range.

According to the thermal stability the order of the material may increase or decrease this depends on the bond strength, So the grain size may increase or decrease as a function of  annealing temperature and annealing time.

I wish this is useful and help you.

Yours

A. El-Denglawey