TY - JOUR
T1 - Site occupancy and magnetic study of Al3+ and Cr3+ co-substituted Y3Fe5O12
AU - Bouziane, K.
AU - Yousif, A.
AU - Widatallah, H. M.
AU - Amighian, J.
PY - 2008/10
Y1 - 2008/10
N2 - Single-phased polycrystalline Y3Fe5-2xAlx CrxO12 garnet samples (x=0, 0.2, 0.4 and 0.6) have been prepared by the conventional ceramic technique. Rietveld refinement of X-ray diffraction patterns of the samples shows them to crystallize in the Ia3d space group and the corresponding lattice constant to decrease with increasing Al3+ and Cr3+ contents (x). Mössbauer results indicate that Cr3+ substitutes for Fe3+ at the octahedral sites whilst Al3+ essentially replaces Fe3+ at the tetrahedral sites. This result indicates that co-doping of Y3Fe5O12 does not affect the preferential site occupancy for separate individual substitution of either Cr3+ or Al3+. The magnetization measurements reveal that the Curie temperature (Tc) monotonically decreases with increasing x while the magnetic moment per unit formula decreases up to x=0.4 and then slightly increases for x=0.6. This reflects a progressive weakening of the ferrimagnetic exchange interaction between the Fe3+ ions at octahedral and tetrahedral sites due to co-substitution. The magnetic moment was calculated using the cations distribution inferred from the Mössbauer data and the collinear ferrimagnetic model, and was found to agree reasonably with the experimentally measured value. The phenomenological amplitude crossover, characterized by the temperature T*, has also been observed in the doped YIG and briefly discussed.
AB - Single-phased polycrystalline Y3Fe5-2xAlx CrxO12 garnet samples (x=0, 0.2, 0.4 and 0.6) have been prepared by the conventional ceramic technique. Rietveld refinement of X-ray diffraction patterns of the samples shows them to crystallize in the Ia3d space group and the corresponding lattice constant to decrease with increasing Al3+ and Cr3+ contents (x). Mössbauer results indicate that Cr3+ substitutes for Fe3+ at the octahedral sites whilst Al3+ essentially replaces Fe3+ at the tetrahedral sites. This result indicates that co-doping of Y3Fe5O12 does not affect the preferential site occupancy for separate individual substitution of either Cr3+ or Al3+. The magnetization measurements reveal that the Curie temperature (Tc) monotonically decreases with increasing x while the magnetic moment per unit formula decreases up to x=0.4 and then slightly increases for x=0.6. This reflects a progressive weakening of the ferrimagnetic exchange interaction between the Fe3+ ions at octahedral and tetrahedral sites due to co-substitution. The magnetic moment was calculated using the cations distribution inferred from the Mössbauer data and the collinear ferrimagnetic model, and was found to agree reasonably with the experimentally measured value. The phenomenological amplitude crossover, characterized by the temperature T*, has also been observed in the doped YIG and briefly discussed.
KW - Co-substitution
KW - Garnet
KW - Magnetism
KW - Site occupancy
UR - http://www.scopus.com/inward/record.url?scp=46049093184&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=46049093184&partnerID=8YFLogxK
U2 - 10.1016/j.jmmm.2008.04.163
DO - 10.1016/j.jmmm.2008.04.163
M3 - Article
AN - SCOPUS:46049093184
SN - 0304-8853
VL - 320
SP - 2330
EP - 2334
JO - Journal of Magnetism and Magnetic Materials
JF - Journal of Magnetism and Magnetic Materials
IS - 19
ER -