Radiation amorphization and recovery of crystal structure in Gd3Ga5O12 single crystals

Abstract

Single crystals of gallium‐gadolinium garnet (GGG) irradiated by fluences of fast neutrons (0 to 3.8 × 1024 m−2) are investigated by X‐ray and magnetic methods. It is found that irradiation with high fluences leads to complete amorphization of the samples. Besides, the samples recover their single crystalline structure under subsequent thermal annealing (excluding the surface layer). It is shown that on amorphization the absolute value of the paramagnetic Curie temperature increases by a factor ≈ 2.

Peculiairities of Magnetic Properties of the Garnet Y2.25Gd0.75Fe5O12 Irradiated by Fast Neutrons

“…The analysis of the data from [6] reveals that the magnetic moment of the Gd 3 ion, in contrast to the Fe 3 ion, practically does not show changes under irradiation. Therefore, it was of interest to study the radiation behaviour of a ªtriple sublatticeº garnet, which comprises both iron and gadolinium ions.…”

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

“…The grounds for the assumption on the constancy of the magnetic moment of the Gd 3+ ions follow from the analysis of the results of Ref. [6], where we studied the radiation induced amorphiza tion of Gd 3 Ga 5 O 1 single crystals. The aim of this work is to check the validity of this assumption.…”

“…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.…”

“…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.…”

Displacement Defect Formation in Complex Oxide Crystals under Irradiation

“…On the base of peculiarities of accumulation kinetics and calculations of RDD concentration [1,18,23] the impact mechanism of radiation defect formation was considered to be responsible for these changes. The structural disordering process begins at neutron fluences higher than 10 18 cm ± ±2 [24,25]. The annealing of induced defects is happening in two steps like in YAG crystals [21].…”