Аңдатпа
Ferrites YbSrFe2O5.5 and YbBaFe2O5.5 are prepared by reacting ytterbium(III) oxide and iron(III) oxide with strontium or barium carbonate in the solid phase. The ferrites crystallize in the orthorhombic system as shown by indexing of their X-ray diffraction patterns with homology modeling: for YbSrFe2O5.5, a = 10.74 ± 0.006 Å, b = 10.93 ± 0.006 Å, c = 16.64 ± 0.046 Å, V 0 = 1953.3 Å3, Z = 16, V subcell 0 = 122.08 Å3, ρX-ray = 6.26 g/cm3, ρpycn = 6.18 ± 0.9 g/cm3; for YbaBaFe2O5.5, a = 10.74 ± 0.013 Å, b = 10.99 ± 0.004 Å, c = 17.16 ± 0.017 Å, V 0 = 2025.4 Å3, Z = 16, V subcell 0 = 126.59 Å3, ρX-ray = 6.69 g/cm3, ρpycn = 6.40 ± 0.32 g/cm3. The calorimetric heat capacities of the ferrites are studied from 298.15 to 673 K. The C ∼ f(T) curves show λ peaks at 448 K for YbSrFe2O5.5 and at 373 K for YbBaFe2O5.5, likely, due to second-order phase transitions. The dielectric constants and electrical resistances of the ferrites are studied as functions of temperature from 293 to 493 K.