Evaluation of the parameters of cation distribution in Y3A5−z B z O12 solid solutions

Dynamical X‐ray diffractometry of the defect structure of garnet crystals

“…For garnet crystals, the most typical point defects are antisite defects and vacancies 14–18. Thus, in accordance with published data the general structural formula of the GGG single crystal with point defects can be written as where $\delta = 3z/2$ , the dodeca‐ {c}, octa‐ [a], and tetrahedral (d) positions of cations are marked by corresponding brackets, x and y are concentrations of Gd 3+ and Ga 3+ antisite defects in octahedral and dodecahedral positions, respectively, markers □ denote vacancies, z and δ are concentrations of vacancies of Ga 3+ cations in octahedral positions and vacancies of O 2– anions, respectively.…”

“…Although the single crystals of garnets on the whole have an almost perfect crystalline structure, nevertheless, various point defects and growth microdefects are present in them 15–18, 20–22. While different physical and chemical methods provide enough complete information about point defects in garnets 15–18, the knowledge on microdefects is considerably more poor 20–22. The observation by methods of optical and electron microscopy have determined such as‐grown microdefects in the garnet crystals as inclusions, pores, and dislocation loops.…”

“…The presence of point defects causes changes of both structure factors and lattice parameters, the later ones can be approximately calculated for rare‐earth garnets by using an empirical formula 17–19. The influence of these changes on Fourier components of crystal polarizability is demonstrated in Fig.…”

Dynamical X‐ray diffraction theory: Characterization of defects and strains in as‐grown and ion‐implanted garnet structures

“…The most typical point defects in garnet crystals are extrinsic substitutional point defects, intrinsic antisite defects, and vacancies (see, e.g., Refs. ). Particularly, the creation of antisite defects in GGG crystals grown by Czochralski method from the melt‐solution (3Gd 2 O 3 + 5Ga 2 O 3 ) occurs due to the gallium evaporation, which causes the change of stoichiometric ratio 3:5 toward the increase of gadolinium cations Gd 3+ .…”

“…The analysis of the immediate contribution of diffuse scattering intensity from various antisite defects and vacancies was performed with using their typical concentrations determined experimentally for GGG crystals namely, and . The performed calculations have shown that in the measured angular ranges for both 444 and 888 reflections these contributions cannot provide the acceptable fit of the observed rocking curves because of their smallness and wide angular intensity distribution .…”