Rhombohedral shaped, single crystal hematite particles with narrow size distribution (<D(TEM)> = 93 ± 2 nm) were prepared by hydrolysis of iron chloride and polymerisation in water. The results of field dependent magnetization measurements at different warmingcooling rates and ac susceptibility measurements at varying frequencies are reported and discussed. Thermal hysteresis (DeltaTM) associated with the Morin transition and field dependence of the Morin temperature (DeltaTM) are observed in warmingcooling cycles (DeltaTM = 25 and 13 K for H = 0.1 and 3 T, respectively) due to the first order phase transition. A frequency dependence of ac susceptibility is observed above TM, as a result of the relaxation of the magnetic moment of hematite particles in the weak-ferromagnetic phase.
Thermal hysteresis of Morin transition in hematite particles
Suber L;Imperatori P;Fiorani D;
2010
Abstract
Rhombohedral shaped, single crystal hematite particles with narrow size distribution (I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.