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Ferritization of Y3+ and Nd3+ ions in the solid state

Ferritization of Y3+ and Nd3+ ions in the solid state was investigated by X-ray powder diffraction, 57Fe Mössbauer and FT-IR spectroscopies. The magnetization measurements were performed with selected samples between 4.2 and 300 K in magnetic fields up to 20 kOe. Incorporation of Nd3+ ions into the garnet-type structure and the formation of solid solutions Y3-xNdxFe5O12 were shown. The unit-cell parameter measured for Y3Fe5O12 was 12.359(3) A, whereas for the initial molar ratio Fe2O3:Y2O3:Nd2O3 = 5:1:2 a value of a unit-cell parameter of 12.512(3) A was measured for the garnet-type solid solution. Hyperfine magnetic fields (HMF) of 487 and 394 kOe at the a- and d-sites, respectively, were measured at RT for Y3Fe5O12, while HMF of 509 kOe was measurd at RT for NdFeO3. The formation of solid solutions, Y3-xNdxFe5O12, caused a gradual shift to lower wave numbers of IR bands defined for Y3Fe5O12. The magnetization measurements of the compounds with nominal composition (Y2Nd)Fe5O12 and (YNd2)Fe5O12 showed that the magnetic moments were higher than in Y3Fe5O12. The magnetic moments at 20 kOe (corrected for presence of some orthoferrite impurity) were 5.75 mu (B) and 6.45 mu (B), respectively, whereas the moment of Y3Fe5O12 was 4.81 mu (B) (even in saturation it is only 5 mu (B). This proves that the Nd sublattice magnetization is coupled ferromagnetically to the total iron magnetization, in agreement with theoretical expectations for the light rare earth garnets. The increase in magnetic moment of (YNd2)Fe5O12 relative to Y3Fe5O12 is less than twice of the increase for (Y2Nd)Fe5O12. This is probably due to the magnetic anisotropy. (Y2Nd)Fe5O12 exhibit a spin reorientation transition around 60 K, previously not noticed.

Ferritization. solid solution. NdFeO3. iron garnets. magnetization. Mossbauer spectroscopy

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