Structural and Magnetic Transformations in Y3Fe5O12 under Neutron Irradiation

Effect of alloying by gadolinium on the magnetic properties of irradiation-amorphized oxides of the Y3 − x Gd x Fe5O12 system

“…The X ray diffraction studies have shown that the irradiation with fast neutrons of the samples of yttrium-gadolinium iron garnets leads to structural changes similar to those observed previously upon the irradiation of the yttrium iron garnet [5], namely, to an increase in the lattice parameter and in the DebyeWaller factor. In the X ray diffraction patterns of irra diated samples, there is observed, along with Bragg reflections, a clearly pronounced diffuse scattering characteristic of the amorphous phase.…”

“…Therefore, it is natural to analyze the radiation induced changes in the magnetic properties of iron garnets depending on the fraction of the sample volume involved in ADCs (С) rather than as a function of the fluence. It has been shown previously [13] that the following dependence exists upon the irradiation of oxides by fast neutrons: To understand this unexpected, at first glance, behavior of the magnetic moments of the Y-Gd iron garnets, let us remember the results of our previous investigations of the radiation induced behavior of Y 3 Fe 5 O 12 [1,5]. Based on an analysis of the total bulk of experimental data, it was established in [5] that a microregion of a crystal of yttrium iron garnet dam aged by a single ADC with an average total volume ͗v͘ consists of a relatively small amorphous core (͗v ap ͘ ≅ 0.13͗v͘) and a defect zone (͗v d ͘ ≅ 0.87͗v͘).…”

“…A brilliant example is the amorphization of the widely used in practice yttrium iron garnet Y 3 Fe 5 O 12 and related compounds [1][2][3][4][5][6]. In the crystalline state, the yttrium iron garnet exhibits a long range ferrimagnetic order, and its resultant magnetic moment is due to the non equivalence of the sublattices in which there are located Fe 3+ ions connected with each other by a neg ative indirect exchange interaction.…”

“…This method makes it possible to consequently trace the change in the magnetic state in the course of the amor phization of the crystalline structure of the garnet. Such investigations were performed on the example of Y 3 Fe 5 O 12 in [4,5]. It has been established that the main factor responsible for the decrease in the magnetization at not very large fluences (Φ ≤ 4.3 × 10 19 cm -2 ), when the concentration of the amorphous phase is still small, is an increase in the degree of covalence [4].…”

“…The amorphous state of oxide with a garnet structure was obtained in [1][2][3][4][5][6] via irradiation by fast neutrons. This method makes it possible to consequently trace the change in the magnetic state in the course of the amor phization of the crystalline structure of the garnet.…”