Effect of Mo3+ ions on Nd3+ spin-lattice relaxation in Y3Al5O12

The content of Mo³⁺ ions in YAG:Nd garnet samples prepared by different technologies has been studied, and the spin-lattice relaxation rate of these ions at temperatures of 4–5 K measured. It is concluded is drawn that Mo³⁺ ions can play the part of rapidly relaxing centers mediating the Nd³⁺ spin-lattice relaxation at liquid-helium temperatures. This may account for a number of features in the spin-lattice relaxation of rare-earth ions in garnets, observed earlier at low temperatures. Fiz. Tverd. Tela (St. Petersburg) 40, 2026–2028 (November 1998)     

Absorption and luminescence of Nd3+:Y3Al5O12

In this paper there are briefly summarized the results of our experimental measurements of the fluorescence spectra, originating in levels of the⁴ F _3/2 term and terminating on the first two terms of the⁴I multipet, and the results of the absorption spectra at room temperature (RT) and at liquid-nitrogen temperature (NT) from which Nd³⁺: Y₃Al₅O₁₂ energy-level diagram was determined. Further, using the splitting of the⁴F_3/2,⁴F_5/2 and⁴F_7/2 terms the crystal-field parameters were calculated.     

Observation of stimulated Raman scattering in Y3Al5O12 single crystals and nanocrystalline ceramics and in these materials activated with laser ions Nd3+ and Yb3+

High-order Raman parametric generation was excited in the visible and near-IR regions on the Stokes and anti-Stokes lines of Y₃Al₅O₁₂ single crystals and nanocrystalline ceramics. All generation components, as well as the χ⁽³⁾-active vibrational modes of these materials, were identified. In connection with the extensive use of the Nd³⁺-and Yb³⁺-doped Y₃Al₅O₁₂ crystals and, in recent years, nanocrystalline Y₃Al₅O₁₂: Nd³⁺ ceramics in laser physics and quantum electronics, the applied aspect of the observed nonlinear properties of these materials is outlined.     

Scintillation properties of Er-doped Y3Al5O12 single crystals

Er-doped Y₃Al₅O₁₂ single crystals with different Er concentrations of 0.1, 1.0, 10, 30, and 50% were grown by the micro-pulling down method. There were several absorption lines due to the Er³⁺ 4f-4f transitions in the transmittance spectra and these lines correspond to the transitions from the ground state of ⁴I_15/2 to the excited states. The photo- and radio-luminescence spectra showed Er³⁺ 4f-4f emissions. Relative light yield under 5.5 MeV alpha-ray irradiation of Er 0.1%:Y₃Al₅O₁₂ was estimated to be 63% of that of Bi₄Ge₃O₁₂.     

Excited state absorption and stimulated emission of Nd3+ in crystals. Part I: Y3Al5O12, YAlO3, and Y2O3

4 F_3/2 excited state of the Nd³⁺ ion in Y₃Al₅O₁₂, YAlO₃, and Y₂O₃ were measured in a continuous wave pump- and probe experiment in a wide spectral range from 850 nm (780 nm for Y₃Al₅O₁₂) to 1500 nm. The cross sections were determined from a comparison with the emission spectra and the simultaneously measured ground state absorption bleaching. The strongest excited state absorption transitions were found in the 1220–1400 nm spectral region due to transitions to the ²G_9/2 and ⁴G_7/2 levels. The spectral positions of the measured transitions are in good agreement with the theoretically expected transitions calculated from the known Stark-level splittings. Received: 4 December 1997/Revised version: 8 May 1998     

Studies of the spin-Hamiltonian parameters and defect structures for the trigonal Mo 3+ centers in Y 3Al 5O 12 and Lu 3Al 5O 12 crystals

The complete diagonalization (of energy matrix) method (CDM) and the perturbation theory method (PTM) are applied to calculate the spin-Hamiltonian (SH) parameters (electron paramagnetic resonance g factors g _//, g _⊥ and zero-field splitting D) of the trigonal Mo ³⁺ centers in Y ₃Al ₅O ₁₂ and Lu ₃Al ₅O ₁₂ crystals. Both methods are based on the cluster approach in which the covalence effect due to the admixture between the d orbitals of central d ⁿ ion and p orbitals of ligands is considered. The g factors calculated by both methods are close to each other and agree with the experimental values. However, the calculated zero-field splittings D from PTM for both crystals are about 84% those from CDM. The reasons that the CDM is preferable to the PTM in the calculations of SH parameters are discussed. The angular distortions of Mo ³⁺ centers in both garnet crystals are predicted.     

Distortion of the Ligand Environment of Gd3+ and Eu2+ Ions in Garnets: Y3Al5O12, Lu3Al5O12, and Y3Ga5O12

Physics of the Solid State - Using experimental second-rank parameters of the spin Hamiltonian of the rhombic centers Gd3+ and Eu2+ in three garnets and the superposition approximation...     

Magnetic-field-controlled polarized luminescence of Y3Al5O12-Tb and Y3Al5O12-Ho garnets

The circularly polarized luminescence spectra of Y₃Al₅O₁₂-Tb and Y₃Al₅O₁₂-Ho garnets are analyzed in the wavelength ranges of the ⁵ D ₄ → ⁷ F ₅ transition in the Tb³⁺ ion and the ⁵ S ₂ → ⁵ I ₈ transition in the Ho³⁺ ion. It is found that the intensities of the orthogonal circularly polarized components of the series of luminescence lines attributed to the studied garnets differ substantially. The results obtained are interpreted in terms of the mixing of the Tb³⁺ and Ho³⁺ electronic states in an external magnetic field.     

Luminescence of Pr3+ ions in Y3Al5−xGaxO12 solid solutions

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 5, pp. 774–778, November, 1991.     

XRD and AFM study of radiation damage induced by swift heavy ions in Y3Al5O12 single crystals

Defects induced in Y₃Al₅O₁₂ single crystals by swift heavy ions are investigated by X-ray diffraction (XRD) and atomic force microscopy. The irradiation was performed at GANIL with 561 MeV ⁵¹Cr, 466 MeV ¹²⁸Te, and 957 MeV ²⁰⁸Pb ions. The XRD data reveal that the lattice strain increases with increasing electronic stopping power, whereas the hillock parameters (height and diameter) are not influenced by the electronic stopping power. According to our experimental data, for the same mean electronic stopping power, the hillock parameters are more pronounced for the lower range in contrast to swelling measurements. The experimental data show a strong increase in the hillock parameter at higher fluence, indicating the amorphization of Y₃Al₅O₁₂ single crystals.     

Field dependence of spin-lattice relaxation in paramagnetic salts

The field dependence of the Raman SLR rate is determined for H₀ of the order of the local field. Both S-state and non S-state transition salts are investigated when (i)H_dip > H_exch and (ii) H_exch > H_dip. Measurements are obtained from the response of the longitudinal magnetization to an amplitude modulated microwave field. The observed dependences agree with Orbach-Huang calculations.     

Yb:Y3Al5O12/Y3Al5O12复合晶体的制作和光谱性能

采用热键合技术,制作中运用不同的工艺参量制作出12片Yb:Y3Al5O12/Y3Al5O12(Yb:YAG/YAG)复合.晶体.利用偏光显微镜对其键合界面进行了观察,研究了样品的透射光谱,从而确定出复合晶体合适的制作工艺.通过透射光谱的形状和透射率来表征复合晶体键合界面的质量.研究表明Yb:YAG/YAG复合晶体键合质量较好,可实现一体化.     

Infrared spectroscopy and lattice dynamical calculations of Gd3Al5O12, Tb3Al5O12 and Lu3Al5O12 single crystals

The infrared (IR) reflectance spectra of Gd₃Al₅O₁₂, Tb₃Al₅O₁₂ and Lu₃Al₅O₁₂ single crystals are studied for the first time. At room temperature, 15 infrared active modes for Lu₃Al₅O₁₂ and 14 for Gd₃Al₅O₁₂, Tb₃Al₅O₁₂, out of the 17 theoretically predicted, have been experimentally recorded. The complex dielectric function the refractive index, the absorption coefficient as well as the longitudinal (ω_LO) and transverse (ω_TO) frequencies of the long-wavelength T_1u modes are determined by the Kramers-Kronig transformation of the reflectance spectra. The experimental data are compared and discussed with the theoretical results obtained by the rigid ion model. Our theoretical analysis reveals that the bonds in the tetrahedra exhibit a covalent character while those in the dodecahedra almost ionic character, which is in accordance with the results for other materials of this crystal family.     

Exchange-mediated spin-lattice relaxation of Fe3+ ions in borate glasses

Spin-lattice relaxation times (T1) of two borate glasses doped with different concentrations of Fe2O3 were measured using the Electron Spin-Echo (ESE) technique at X-band (9.630 GHz) in the temperature range 2-6K. In comparison with a previous investigation of Fe3+-doped silicate glasses, the relaxation rates were comparable and differed by no more than a factor of two. The data presented here extend those previously reported for borate glasses in the 10-250K range but measured using the amplitude-modulation technique. The T1 values were found to depend on temperature (T) as T(n) with n approximately 1 for the 1% and 0.1% Fe2O3-doped glass samples. These results are consistent with spin-lattice relaxation as effected by exchange interaction of a Fe3+ spin exchange-coupled to another Fe3+ spin in an amorphous material.