Wyniki wyszukiwania - BazTech

Ograniczanie wyników

1 Materials Science Poland

1 2012

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: EPR vanadates

Sortuj według:

Ogranicz wyniki do:

Study of magnetic inhomogeneity in b-Cu3Fe4V6O24

Guskos N., Zolnierkiewicz G., Typek J., Szymczak R., Blonska-Tabero A.

Materials Science Poland

2012

Vol. 30, No. 1

1--9

The temperature dependence of dc magnetization and electron paramagnetic resonance (EPR) spectra of the b-Cu3Fe4V6O24 multicomponent vanadate were investigated. Dc magnetic measurements showed the presence of strong antiferromagnetic interactions (Curie-Weiss temperature, Q 80 K) at high temperatures, while zero-field-cooled (ZFC) magnetization revealed a cusp-like maximum in low fields at Tf 1 =4.4 K, which coincides with the splitting of the ZFC and FC curves. Another maximum was registered at Tf 2 = 3.0 K. These two temperatures (Tf 1 and Tf 2) could be regarded as freezing temperatures in the spin glass state of two magnetic sublattices of Fe1 and Fe2 ions. The EPR spectrum of b-Cu3Fe4V6O24 is dominated by a nearly symmetrical, very intense and broad resonance line centered at geff 2.0 that could be attributed to iron ions. Below 10 K, an additional EPR spectrum with g1 = 2.018(1) and g2 = 2.175(1) appears, as well as a very weak line at geff = 1.99(1). The former spectrum is probably is due to divalent copper ions, and the latter line due to vanadium V4+ complexes. The temperature dependence of EPR parameters (g-factor, linewidth, integrated intensity) was determined in the range of 3 - 300 K. Two low-temperature maxima in the temperature dependence of the integrated intensity (at 40 and 6 K) were fitted with a function suitable for pairs of exchange-coupled Fe3+ ions. A comparison of dc magnetic susceptibility and EPR integrated intensity indicates the presence of spin clusters, which play an important role in determining the low-temperature magnetic response of b-Cu3Fe4V6O24.