Long time permittivity decay in commensurate phase of Rb2ZnCl4 single crystal

The decay of the permittivity of Rb2ZnCl4 is studied over ten days in the c ommensurate phase. No equilibrium state is actually found alter an experien ce of twelve days. Assuming that the heating branch may represent the equil ibrium state a three-component relaxation law is obtained with three differ ent relaxation time. These relaxation times are connected to three differen t mechanisms of permittivity decay: six domain wall merging, pair annihilat ion and pinning to defects.