The study of magnetic ordering in the spinel system ZnxNi1−xFeCrO4 by neutron diffraction

Studies of the magnetic ordering in the spinel system Zn0.4Co0.6AlxFe2−xO4 by neutron diffraction

“…The diffuse signal broadens the (1 1 1) diffraction peak and this broadening effect is extended up to the position appropriate for the (2 0 0) reflection (2θ = 15.277 • ). The diffuse signal below the (1 1 1) peak in the diffraction patterns indicates the formation of magnetic spin clusters [6,7,[23][24][25]30] in all the composition under investigation. Scattering from these clusters has given rise to this diffuse signal which has broadened the (1 1 1) Bragg peak.…”

“…Among them the compound Zn x Ni 1−x FeCrO 4 was characterized as semispin-glass for x ≥ 0.6 [24], the system Zn x Cu 1−x FeCrO 4 was characterized as semi-spin-glass at x = 0.6 while it behaves as cluster spin-glass at x = 0.8 and at x = 0.75 [25]. The system Zn x Mg 0.75−x Cu 0.25 Fe 2 O 4 was reported to be a cluster spin-glass on the basis of the various features observed in our neutron diffraction patterns recorded as a function of temperature [6].…”

Mössbauer study of the re-entrant spin-glass behaviour in the mixed spinel ferrites Mg(0.9+x)Fe2(1−x)Ni0.1TixO4 (x=0.5 and 0.6)

“…Also in the re-entrant Li 1.125 Ti 1.25 Fe 0.625 O 4 a (super)paramagnetic component was observed by Dormann et al [16] in the Mössbauer spectra, which prevent them to explain the observed magnetic features of this diluted spinel on the basis of the LCS model. The occurrence of magnetic clusters was further reported for various re-entrant SG systems [17,19] and one generally named these systems as ''cluster'' spin-glasses. In a previous work on the spin-glass Fe 0.6 Mg 1.6 Ni 0.1 Ti 0.7 O 4 [11], the present authors have established that the as-prepared sample shows typical SP features whereas after several times of reheating this sample the finally obtained material shows rather rigorous spin-glass behaviour.…”

Кристаллическая и магнитная структура гранулированных порошков Mn-Zn- и Ni-Zn-ферритов шпинелей

“…Анализ дифракционных данных указывает на то, что кристаллическая структура всех исследуемых соедине-ний описывается кубической симметрией с простран-ственной группой Fd3m [8]. Особенностью кубиче-ской структуры марганец-цинковых, никель-цинковых и магний-цинковых ферритов является наличие двух типов кристаллографических позиций с неэквивалент-ным кислородным окружением: тетраэдрической A для катионов Zn, октаэдрической B для катионов Mn, Ni и Mg. В кубической структуре с симметрией про-странственной группы Fd3m катионы Zn находятся в позициях 8(a) (1/8, 1/8, 1/8), катионы Mn, Ni и Mg -в позициях 16(b) (1/2, 1/2, 1/2), а анионы кислорода -в позициях 32(e) (x, x, x) [22][23][24]10]. Из дифракцион-ных данных были рассчитаны параметры элементарной ячейки и позиционный параметр x для кислорода в октаэдрическом окружении.…”