Aluminium-gallium substitution in yttrium garnets investigated by NMR

Gautier, N.; Massiot, Dominique; Farnan, Ian; Coutures, J.P.

doi:10.1051/jcp/1995921843

Cited by 10 publications

(12 citation statements)

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“…In accordance with the previous studies [29,35,36], 27 Al MAS NMR allows easy separation of spectral lines from Al ions in the tetrahedral and octahedral positions of garnet structure. 27 Al MAS NMR spectra of Lu3GaxAl5-xO12:Ce single crystals obtained with the spinning rate of 22…”

Section: Nmr Investigation Of Ga and Al Distribution In Lu3gaxal5-xo1supporting

confidence: 89%

Influence of gallium content on Ga3+ position and photo- and thermally stimulated luminescence in Ce3+-doped multicomponent (Y,Lu)3GaxAl5-xO12 garnets

Babin

Buryi

Chlan

et al. 2018

Journal of Luminescence

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Photoluminescence, thermally stimulated luminescence (TSL) and EPR characteristics of the Ce 3+ -doped single crystals of multicomponent Y1Lu2GaxAl5-xO12 and Lu3GaxAl5-xO12 garnets with different Ga contents (x = 0, 1, 2, 3, 4, 5) excited in the Ce 3+ -related absorption bands are investigated in the 9 -500 K temperature range. The distribution of Ga 3+ and Al 3+ ions in the crystal lattice is determined by the NMR method. The relative number of Ga 3+ ions in the tetrahedral crystal lattice sites, the maxima positions of the TSL glow curve peaks and the corresponding trap depths are found to decrease linearly with the increasing Ga content. At the same time, the reduction of the activation energy Ea of the TSL glow curve peaks creation under irradiation in the 4f -5d1 absorption band of Ce 3+ is strongly nonlinear. To explain this effect, the suggestion is made that Ea is the energy distance between the excited 5d1 level of Ce 3+ and a defect level located between the 5d1 level and the bottom of the conduction band and arising from the Ga 3+ ion perturbed by the nearest neighboring Ce 3+ ion. The electrons thermally released from the excited Ce 3+ ions are suggested to be trapped at the perturbed Ga 3+ ions resulting in the appearance of electron Ga 2+ centers. In spite of the fact that the paramagnetic Ga 2+ ions were not detected by EPR, the described above process was found for Fe 3+ impurity ions, namely the electron transfer from the 5d1 excited levels of Ce 3+ to Fe 3+ was directly detected by EPR.

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Section: Nmr Investigation Of Ga and Al Distribution In Lu3gaxal5-xo1supporting

confidence: 89%

Influence of gallium content on Ga3+ position and photo- and thermally stimulated luminescence in Ce3+-doped multicomponent (Y,Lu)3GaxAl5-xO12 garnets

Babin

Buryi

Chlan

et al. 2018

Journal of Luminescence

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“…The signal is too noisy for the second film (Figure b) with the thickness of only 7 μm but a larger Ga concentration x = 2. The spectrum in this film is also broader than that with x = 0.3 due to an increase of quadrupole coupling with increasing Ga concentration . This factor also reduces the intensity of NMR spectrum.…”

Section: Nmr Investigation Of Ga3+ and Al3+ Distribution In The Y3al5...mentioning

confidence: 83%

“…These spectra represent only the 1/2 ↔ −1/2 central transition, whose frequency is defined by the chemical shift mechanism and second order quadrupole interaction according to eq . Because the Al VI site is characterized by small quadrupole frequency (in the Y 3 Al 5– x Ga x O 12 solid solution C Q increases from 0.637 to ∼1.4 MHz), corresponding NMR lines remain almost unchanged under the crystal rotation. In contrast, the NMR lines responsible for the Al IV sites are markedly (8–12 kHz) shifted from the Larmor frequency by the isotropic chemical shift and quadrupole coupling, which are much larger for the Al IV site comparing to the Al VI site (Table ).…”

Section: Nmr Investigation Of Ga3+ and Al3+ Distribution In The Y3al5...mentioning

confidence: 99%

Aluminum and Gallium Substitution in Yttrium and Lutetium Aluminum–Gallium Garnets: Investigation by Single-Crystal NMR and TSL Methods

et al. 2016

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The work reports the results on 71 Ga and 27 Al NMR investigation of the gallium and aluminum ions distribution over tetrahedral and octahedral positions in the Y 3 Al 5−x Ga x O 12 :Ce single crystals and Lu 3 Al 5−x Ga x O 12 :Ce single-crystalline epitaxial films. The gallium content x varies between 0 and 5 in crystals and between 0.3 and 2 in films.. We find that in both the Y-and Lu-based solid solutions the larger gallium ions are preferably located at the tetrahedral position while the smaller aluminum ions prefer the octahedral position of the garnet host. Based on NMR data, the dependence of fractional occupation parameters of the tetrahedral site of Ga and Al ions on the Ga content is determined. In particular, in the Y 3 Al 2 Ga 3 O 12 :Ce crystal only 28% of Ga ions occupy octahedral sites, whereas 72% occupy tetrahedral ones. NMR investigations suggest that observed nonmonotonic dependences of electron trap depths monitored by thermally stimulated luminescence of Y 3 Al 5−x Ga x O 12 :Ce complex garnets on the Ga content are related to preferential localization of the Ga and Al ions over the tetrahedral and octahedral positions of the garnet lattice, respectively. Our data confirm that the tetrahedral site preference (over the octahedral site) for the Ga occupation is an intrinsic property of the mixed Y 3 (Lu 3 )Al 5−x Ga x O 12 garnets.

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“…The spectra have thus been acquired in static conditions as a sum of nine full echo signals obtained by varying the offset of the carrier frequency (with a 100 kHz step), according to the VOCS protocol that we have recently described in a study of 69,71 Ga in b-Ga 2 O 3 . 5 The second order quadrupolar broadening is so high in these compounds that MAS experiments cannot give resolution (unlike aluminophosphonates, for which MQ 27 Al MAS has proved to be efficient), 6 while the possible DAS 7 or newly described QPASS 8 experiments remain ineffective.…”

mentioning

confidence: 99%

71Ga and 31P solid state NMR: a powerful tool for the characterization of the first gallium phosphonates

Bujoli¹,

Fredoueil²,

Massiot³

et al. 1998

Chem. Commun.

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Aluminium-gallium substitution in yttrium garnets investigated by NMR

Cited by 10 publications

References 0 publications

Influence of gallium content on Ga3+ position and photo- and thermally stimulated luminescence in Ce3+-doped multicomponent (Y,Lu)3GaxAl5-xO12 garnets

Influence of gallium content on Ga3+ position and photo- and thermally stimulated luminescence in Ce3+-doped multicomponent (Y,Lu)3GaxAl5-xO12 garnets

Aluminum and Gallium Substitution in Yttrium and Lutetium Aluminum–Gallium Garnets: Investigation by Single-Crystal NMR and TSL Methods

71Ga and 31P solid state NMR: a powerful tool for the characterization of the first gallium phosphonates

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