Conduction mechanism and magnetic behavior of dysprosium strontium iron garnet (DySrIG) nanocrystals

Garnet nanoparticles Dy2.8Sr0.2Fe5O12 (DySrIG) were prepared by citrate auto-combustion method and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and differential thermal analysis (DTA). The suitable formation of this garnet in single phase was at 1100 degrees C with crystallite of size 95 nm. The Curie temperature of DySrIG is obtained at 610K. The effective magnetic moment mu(eff) was calculated experimentally and theoretically and they are compatible with each other. The dielectric constant epsilon' increases from order 10(2) at room temperature to 10(4) at 850 K passing by four transition temperatures. The temperature dependence of the resistivity of DySrIG at different frequencies (f) 100 kHz <= f <= 5 MHz indicates the presence of 5 transition temperatures which are slightly different from those of epsilon' data. The resistivity data are frequency independent at f < 1 MHz. The transition height is decreased by increasing the temperature from approximate to 5 M Omega cm at 320 K and 200 kHz to approximate to 20 Omega cm at 700 K. Accordingly, Dy2.8Sr0.2Fe5O12 (DySrIG) is recommended for the use in phase shifter, circulators and microwave applications. (C) 2010 Elsevier BM. All rights reserved.