Optical, Structural, and Mechanical Properties of Gd₃Ga₅O₁₂ Single Crystals Irradiated with ⁸⁴Kr⁺ Ions

Abstract

Herein, the optical absorption, X‐ray diffraction (XRD) analysis data, and mechanical properties along the ion path are analyzed for gadolinium gallium garnet (Gd3Ga5O12 or GGG) single crystals irradiated with fast 84Kr ions to fluences of 1013–1014 ion cm−2. It is found that the optical absorption spectra of Czochralski‐grown unirradiated GGG crystal consist of relatively narrow lines in the UV spectral range associated with the 4f–4f transitions in Gd3+ ions. Transitions from the 6S7/2 ground state to the 6P, 6J, and 6D states in the Gd3+ cation are visible. An additional absorption band is also observed at 350 nm, which is associated with an uncontrolled Ca impurity. In irradiated GGG single crystals, a shift of the fundamental absorption edge by ≈30 nm to the long‐wavelength part of the spectrum is observed. The observed changes are caused by structural disturbances caused by depletion of the surface layer and an increase in the number of displaced atoms accompanied by an increase in the crystal lattice parameter. XRD analysis shows the presence of size effects and deformation of interplanar distances due to the displacement of atoms from the sites of the crystal lattice with subsequent migration. Hardness measurements show ion‐induced softening, which may be due to ion‐induced amorphization.

Paramagnetic Defects and Thermoluminescence in Irradiated Nanostructured Monoclinic Zirconium Dioxide

“…It is also known that when ZrO 2 is irradiated with ions with an energy above the threshold, an intense generation of anion vacancies occurs in it, which can also contribute to the formation of complex defects [ 40 , 53 , 54 ]. In the past few years, a large number of such complex defects have been studied in detail in MgO, Al 2 O 3 , and Gd 3 Ga 5 O 12 crystals [ 55 , 56 , 57 , 58 , 59 , 60 ].…”

Defect‐Induced Effects in Nanomaterials

“…Karipbayev et al presented a study of the optical, structural, and mechanical properties of Gd 3 Ga 5 O 12 single crystals irradiated by 84 Kr þ ions. [6] The observed changes are ascribed to structural disturbances caused by depletion of the surface layer and an increase in the number of displaced atoms, accompanied by an increase in the crystal lattice parameter. C. Barone et al combined measurements of broadband optical spectroscopy (10 meV to 6 eV), electrical resistivity and Hall effect to study the effects of gamma irradiation on electronic and optical properties of Ga-doped ZnO thin films.…”

Structural Damage and Recrystallization Response of Garnet Crystals to Intense Electronic Excitation

“…Focusing on GGG samples that possess a very strong ability to resist color center formation, a series of absorption bands at 275, 306, and 313 nm in the UV region below 400 nm associated with electronic transitions in Gd 3+ are assigned to 8 S 7/2 → 6 D j , 8 S 7/2 → 6 I j , and 8 S 7/2 → 6 P j , respectively. [66] In addition to an overall increase in absorbance, the fundamental absorption edge red-shifts by 20-35 nm to the long-wavelength part of the spectra (UV-vis) after Xe 35+ irradiation with increasing fluence, which is caused by an irradiation-induced structural disorder in the surface layer. Utilizing the Kubelka-Munk function to fit (αhυ) 2 versus the photon energy (hυ) extracted from the absorption band spectrum (αhv = A(hv − E g ) 1/2 ), [67][68][69][70] it is evidenced that the bandgap width has been reduced by extrapolating this linear region onto the x-axis, which is dependent on increasing fluences of Xe 35+ onto both garnets.…”