Mossbauer spectrometry of A(2)FeMoO(6) (A = Ca,Sr,Ba): Search for antiphase domains - art. no. 174403

Mossbauer spectrometry was carried out in the range of temperature from 4 K to well above the Curie temperature on polycrystalline ceramics of A(2)FeM oO(6) (A=Ca,Sr,Ba). A secondary component in all the paramagnetic or ferrom agnetic,spectra is attributed to iron in the vicinity of a defect in the Na Cl-type cation order. The secondary component and the lack of saturation of the magnetization at the half metallic value of 4 mu (B)/formula unit are explained in terms of antisite defects (point defects) and antiphase bounda ries (planar defects). The point defects predominate in all three compounds , but there is some evidence of antiphase boundaries from the spectrum of t he Ca compound in a 6 T applied field. The dimensions of the antiphase doma ins are estimated to be of order 0.5 mum. The electronic configuration of i ron in the Ca and Sr compounds is close to 3d(5.2), whereas it is' 3d(5.5) in the Ba compound.