Ferrites YbSrFe₂O_5.5 and YbBaFe₂O_5.5:
Synthesis and X-ray Diffraction, Thermodynamic,
and Electrophysical Properties

B. K. Kasenov, E. G. Tolokonnikov, E. S. Mustafin, Sh. B. Kasenova,
S. Zh. Davrenbekov, Zh. I. Sagintaeva, and E. K. Zhumadilov

Institute of Phytochemistry, Ministry of Education and Sciences of Kazakhstan,
ul. Erzhanova 19, Karaganda, 470032 Kazakhstan

e-mail: phytoinform@nursat.kz

Received December 24, 2004

Abstract—Ferrites YbSrFe₂O_5.5 and YbBaFe₂O_5.5 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 YbSrFe₂O_5.5 , a = 10.74±
0.006 Å, b = 10.93 ± 0.006 Å, c = 16.64 ± 0.046 Å, V⁰ = 1953.3 ų, Z = 16, = 122.08 ų, _X-ray =
6.26g/cm³ , _pycn = 6.18 ± 0.9 g/cm³; for YbaBaFe₂O_5.5 , a = 10.74 ± 0.013 Å, b = 10.99 ± 0.004 Å, c = 17.16±
0.017 Å, V⁰ = 2025.4 ų, Z = 16, = 126.59 ų , _X-ray = 6.69 g/cm³ , _pycn = 6.40 ± 0.32 g/cm³ . The
calorimetric heat capacities of the ferrites are studied from 298.15 to 673 K. The ~ f (T) curves show peaks
at 448 K for YbSrFe₂O_5.5 and at 373 K for YbBaFe₂O_5.5 , 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.

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