Dynamics of phase transitions in Ba1-x Srx V13 O18

We studied the slow dynamics of phase transitions in Ba1-xSrxV13O18, which is composed of quasitriangular lattices of V ions and exhibits a phase transition into a V orbital ordered state with V trimerization. We found a clear time dependence of magnetic susceptibility and strain on a phase transition, and the transformation time estimated from the time dependence exhibits a peculiar temperature dependence, consistent with nucleation-growth behavior. Detailed analysis indicates that there is a distribution of the transformation time in Ba1-xSrxV13O18, and the formation of twin structures associated with the phase transition may affect the nucleation-growth dynamics and causes such a distribution of the transformation time.