Structural modifications of yttrium iron garnet after high-energy heavy ion irradiations

Costantini, Jean‐Marc; Ravel, F.; Brisard, F.; Caput, M.; Cluzeau, C.

doi:10.1016/0168-583x(93)90777-4

Cited by 30 publications

(20 citation statements)

References 12 publications

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“…The good concordance between swelling and XRD results indicates that swelling in Y 3 Al 5 O 12 is due to the volume expansion induced by the phase transition from crystalline to amorphous phase, in agreement with observation made in other oxides [35][36][37][38]. It is also important to note that for the same mean electronic stopping power (31 keV/nm) (see Fig.…”

Section: Discussionsupporting

confidence: 80%

Radiation damage induced by swift heavy ions and reactor neutrons in Y3Al5O12 single crystals

Izerrouken

Meftah

Nekkab

2007

Nuclear Instruments and Methods in Physics Research Section B:

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Section: Discussionsupporting

confidence: 80%

Radiation damage induced by swift heavy ions and reactor neutrons in Y3Al5O12 single crystals

Izerrouken

Meftah

Nekkab

2007

Nuclear Instruments and Methods in Physics Research Section B:

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“…[42][43][44][45][46][47][48][49] For mica, e.g., the radius of the protrusions 46 coincides well with the track radius deduced from other techniques 24 since the protrusions are negligible due to fresh cleaving or very little on a surface directly exposed to ion irradiation (in contrast to other materials, the height of the protrusions in mica are too small for quantitative size analysis 47 ). The results obtained from several direct (TEM, SFM) and indirect [Mössbauer spectrometry, Channeling Rutherford Backscattering (C-RBS) and x-ray diffraction (XRD)] observation methods lead to a consistent determination of the S e thresholds in various amorphizable insulators including mica, 24,43,46,48,50,51 yttrium iron garnet (Y 3 Fe 5 O 12 ), 52,53 gadolinium gallium garnet (Gd 3 Ga 5 O 12 ), 54,55 and crystalline quartz (SiO 2 ). 30,56 When comparing track sizes and S e thresholds from different irradiation experiments, it is important to check if the velocities of the projectiles are similar.…”

Section: -1mentioning

confidence: 99%

Dense and nanometric electronic excitations induced by swift heavy ions in an ionic CaF2crystal: Evidence for two thresholds of damage creation

et al. 2012

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CaF 2 crystals as representatives of the class of ionic nonamorphizable insulators were irradiated with many different swift heavy ions of energy above 0.5 MeV/u providing a broad range of electronic energy losses (S e ). Beam-induced modifications were characterized by Channeling Rutherford Backscattering Spectrometry (C-RBS) and x-ray diffraction (XRD), complemented by transmission electron microscopy (TEM). Results from C-RBS give evidence of significant damage appearing above a S e threshold of 5 ± 2 keV/nm. A second critical S e appears around 18 ± 3 keV/nm; below this value the damage as function of ion fluence saturates at 20%, while above this the damage saturation level increases with S e , reaching ∼60% for ions of S e = 30 keV/nm. XRD measurements also show effects indicating two threshold values. Above 5 keV/nm, the widths of the XRD reflection peaks increase due to the formation of nanograins, as seen by TEM, while a significant decrease of the peak areas only occurs above 18 keV/nm. The track radii deduced from C-RBS measurements are in agreement with those extracted from the fluence evolution of the widths of the XRD peaks. Moreover, track radii deduced from the peak area analysis are slightly smaller but in agreement with previous track observations by high resolution electron microscopy. Calculations based on the inelastic thermal spike model suggest that the lower threshold at 5 keV/nm is linked to the quenching of the molten phase, whereas the threshold at 18 keV/nm can be interpreted as quenching of the boiling phase. The results of CaF 2 are compared with other nonamorphizable materials such as LiF and UO 2 .

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“…We have also shown by high-resolution transmission electron microscopy ͑HRTEM͒ that, in the low ion velocity range, recrystallization of the amorphous tracks occurs in undoped YIG thin epitaxial films due to track overlap at a low a͒ Author to whom correspondence should be addressed; electronic mail: costantini@drnsac.cea.fr at CEA/SACLAY, DMT/SEMI, F-31131, GiF-SUR-YVETTE Cedex, France fluence. 6,7 A nanocrystalline phase is then produced under the ion beams with grain sizes around 10 nm 6 and a much larger electrical conductivity. 7 The nanograins are embedded within a matrix made of amorphous and single-crystalline YIG with relative fractions depending on the fluence and S e .…”

Section: Introductionmentioning

confidence: 99%

“…7 The nanograins are embedded within a matrix made of amorphous and single-crystalline YIG with relative fractions depending on the fluence and S e . 6 At a fluence of 4.5ϫ10 12 cm Ϫ2 with 50 MeV 63 Cu ion irradiations ͑90% of amorphous phase͒, the nanograins are widely separated with an average distance around 20 nm that decreases at higher fluence when the recrystallization proceeds. 6 The thermal spike model was then adapted to interpret the nanophase formation from the amorphous phase in the same way as was done in the case of amorphous track formation.…”

Section: Introductionmentioning

confidence: 99%

“…6 At a fluence of 4.5ϫ10 12 cm Ϫ2 with 50 MeV 63 Cu ion irradiations ͑90% of amorphous phase͒, the nanograins are widely separated with an average distance around 20 nm that decreases at higher fluence when the recrystallization proceeds. 6 The thermal spike model was then adapted to interpret the nanophase formation from the amorphous phase in the same way as was done in the case of amorphous track formation. 7 It was also found that p-o rn-type doping of the YIG films respectively with divalent (Ca 2ϩ ) or tetravalent (Si 4ϩ ) ions did not change the amorphization and recrystallization processes in the thin films, although the electrical conductivity of the pristine films was increased up to eight orders of magnitude.…”

Section: Introductionmentioning

confidence: 99%

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Local order and magnetic behavior of amorphous and nanocrystalline yttrium iron garnet produced by swift heavy ion irradiations

Costantini

Desvignes

Pérez

et al. 2000

Journal of Applied Physics

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International audienceThin epitaxial films of gallium or scandium-doped and undoped yttrium iron garnet (Y3Fe5O12 or YIG) on nonmagnetic Gd3Ga5O12 substrates were irradiated with swift heavy ions (50 MeV 32S, 50 MeV 63Cu, and 235 MeV 84Kr) in the electronic slowing down regime. The mean electronic stopping power in the films was always larger than the threshold for amorphous track formation in YIG which is around 4.5 MeV/μm in this low ion-velocity range. The local order and magnetic properties of the damaged films were then studied at room temperature by 57Fe conversion electron Mössbauer spectroscopy (CEMS) and x-ray absorption spectroscopy (XAS) at the iron K edge in the fluorescence mode. In the case of paramagnetic gallium or scandium-substituted films (YIG:Ga, YIG:Sc) irradiated with 32S or 63Cu ions, the CEMS data show that the tetrahedral Fe3+ sites are preferentially damaged, while the octahedral sites are conserved. This is confirmed by the decrease of the pre-edge peak in the XAS data of the ferrimagnetic undoped YIG films showing that the number of tetrahedral iron sites is decreased in the amorphous phase obtained with 84Kr ion irradiation, due to the formation of fivefold-coordinated pyramidal sites, as already found in a previous study on undoped YIG sinters amorphized by 3.5 GeV 132Xe ion irradiation. In the case of the nanophase induced by ion-beam recrystallization of the tracks with 32S or 63Cu irradiations, a further decrease of the pre-edge peak is found. This is interpreted by (i) an increase of the fivefold-coordinated pyramidal sites and/or (ii) a probable decomposition of the garnet into orthoferrite (YFeO3) and haematite (α-Fe2O3) under the high-pressure and high-temperature conditions in the thermal spike generated by the ions. The CEMS data of irradiated undoped YIG also show that both the amorphous and nanocrystalline phases have a paramagnetic behavior at room temperature. The nanophase magnetic behavior is analyzed on the basis of a superparamagnetic relaxation above the blocking temperature, whereas the amorphous phase behavior is ascribed to a speromagnetic state

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Structural modifications of yttrium iron garnet after high-energy heavy ion irradiations

Cited by 30 publications

References 12 publications

Radiation damage induced by swift heavy ions and reactor neutrons in Y3Al5O12 single crystals

Radiation damage induced by swift heavy ions and reactor neutrons in Y3Al5O12 single crystals

Dense and nanometric electronic excitations induced by swift heavy ions in an ionic CaF2crystal: Evidence for two thresholds of damage creation

Local order and magnetic behavior of amorphous and nanocrystalline yttrium iron garnet produced by swift heavy ion irradiations

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