RE Atoms Research Articles

Precipitation in Mg-Gd-Y-Zr Alloy: Atomic-scale insights into structures and transformations

This paper reports on a comprehensive investigation, using atomic-scaled Cs corrected high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), of the precipitation in Mg-9.28Gd-2.93Y-0.35Zr, including structures of the precipitates and several structural transformation processes. The precipitation sequence is identified as: Super saturated solid solution→clusters→nucleation β' (major)/βH (minor)→precipitate β' (major)/βM,βT' (minor)→β1→β(Equilibrium). Under peak-age condition, the strengthening structure is independent defect-free β' with little interaction among each other. Under over-age condition, the β' precipitates start to interact with each other, during which coarsening and orientation transformation of β' precipitates take place. The coarsening and orientation transformation, in which some RE atoms in the precipitates need to change their positions, are achieved by βM and βT' as transitional structures.

Syntheses, crystal and electronic structures of ternary rare-earth zirconium sulfides, RE2ZrS5 (RE = Y, Ce and Pr)

Three ternary rare-earth zirconium sulfides, Y2ZrS5 (1), Ce2ZrS5 (2) and Pr2ZrS5 (3), have been synthesized by high-temperature solid-state reactions. They crystallize in the space group Pnma of the orthorhombic system, belonging to the Y2HfS5 structure type. There are two types of building units in their structures, RES8 bicapped trigonal prisms and ZrS7 monocapped trigonal prisms. Their structures feature polyanionic {[ZrS5]6−}n chains and cubane-like {[RE4Zr2S6]8+}n double chains along the b direction, and RE atoms occupying the polyhedral interspaces between the former chains. The lanthanide contraction phenomenon in the series of RE2ZrS5 (RE=La–Nd, Sm and Gd) is discussed. The electronic band structure and density of states calculations using Material Studio indicate that the direct optical energy gap of 1 is 1.39eV and the optical absorption is mainly ascribed to the charge transition from S-3p to Y-4d and Zr-4d states.

Oxidation Effects in Rare Earth Doped Topological Insulator Thin Films.

The breaking of time-reversal symmetry (TRS) in topological insulators is a prerequisite for unlocking their exotic properties and for observing the quantum anomalous Hall effect (QAHE). The incorporation of dopants which exhibit magnetic long-range order is the most promising approach for TRS-breaking. REBiTe3, wherein 50% of the Bi is substitutionally replaced by a RE atom (RE = Gd, Dy, and Ho), is a predicted QAHE system. Despite the low solubility of REs in bulk crystals of a few %, highly doped thin films have been demonstrated, which are free of secondary phases and of high crystalline quality. Here we study the effects of exposure to atmosphere of rare earth-doped Bi2(Se, Te)3 thin films using x-ray absorption spectroscopy. We demonstrate that these RE dopants are all trivalent and effectively substitute for Bi3+ in the Bi2(Se, Te)3 matrix. We find an unexpected high degree of sample oxidation for the most highly doped samples, which is not restricted to the surface of the films. In the low-doping limit, the RE-doped films mostly show surface oxidation, which can be prevented by surface passivation, encapsulation, or in-situ cleaving to recover the topological surface state.

Crystal Structure, Magnetic, Electronic, and Thermal Transport Properties of Ternary Compounds REReB4 (RE = Ce, Gd–Er, Yb)

AbstractRare‐earth rhenium borides REReB4 (RE = Ce, Gd–Er, Yb) were synthesized by various methods, including spark plasma sintering. They crystallize with the YCrB4 structure type (space group Pbam). The Tb, Ho, Er, and Yb representatives are Curie–Weiss paramagnets with the RE atoms in the +3 oxidation state, whereas the cerium atoms in CeReB4 are in the 4f0 configuration (oxidation state +4). Electronic‐structure calculations predict CeReB4 to be a metal with a density of states N(EF) = 1.6 states eV–1 f.u.–1 (f.u.: formula unit). Measurements of the transport properties confirm that REReB4 (RE = Ce, Tb, Ho) are metallic materials with low thermopowers and relatively high thermal conductivities.

Mechanical and electrical properties of an ultrafine grained Al–8.5 wt. % RE (RE = 5.4 wt.% Ce, 3.1 wt.% La) alloy processed by severe plastic deformation

This work focuses on the effect of high pressure torsion (HPT) on the thermostability, microstructure, mechanical properties and electrical conductivity of an Al–8.5wt.% RE (RE stands for rare earth Ce and La in the present case) alloy with respect to its potential application in electrical engineering. HPT processing leads to the formation of a very homogeneous ultra-fine grained microstructure resulting from the fragmentation of RE-rich intermetallic particles down to the nanoscale. Deformation induced supersaturated solid solution of RE atoms in the Al matrix is demonstrated for the first time. The HPT processed material shows an extraordinary high mechanical strength attributed to the high volume fraction of nanoscaled intermetallic particles and the ultrafine grained (UFG) microstructure. The various strengthening contributions were analyzed, and it was shown that the increase of strength during short time annealing could be attributed to the clustering of RE atoms in solid solution. The HPT processing induces a significant reduction of the electrical conductivity, but it was partly restored by annealing thanks to the concomitant clustering of RE atoms, reduction of dislocation density and grain growth. The potential applications of UFG Al–RE alloys in electrical engineering are finally discussed.

Chemical pressure effects on the spectroscopic properties of Nd^3+-doped gallium nano-garnets

Nd3+-doped RE3Ga5O12 (RE = Gd, Y, and Lu) nano-crystalline garnets of 40-45 nm in size have been synthesized by a sol-gel method. With the decrease of the RE atom size, the chemical pressure related to the decreasing volumes of the GaO4 tetrahedral, GaO6 octahedral and REO8 dodecahedral units drive the nano-garnets toward a more compacted structure, which is evidenced by the change of the vibrational phonon mode frequencies. The chemical pressure also increases the crystal-field strength felt by the RE3+ ions while decreases the orthorhombic distortion of the REO8 local environment. These effects alter the absorption and emission properties of the Nd3+ ion measured in the near-infrared luminescence range from 0.87 to 1.43 μm associated with the 4F3/2→4IJ (J = 9/2, 11/2, 13/2) transitions. The 4F3/2 luminescence decay curves show non-exponential behavior due to dipole-dipole energy transfer interactions among Nd3+ ions that increases with pressure.

Structural, electronic and magnetic properties of RE2Ti3Si4 (RE = Gd, Tb, Er) compounds: A first principle study

Electronic and magnetic properties of the RE2Ti3Si4 (RE=Gd, Tb, Er) compounds have been investigated by means of LSDA+U method which is based on the density functional theory (DFT). Excellent agreement is obtained between the calculated and experimental values for the structural parameters, which indicates that the method we used at the present is reasonable. Mulliken analysis shows that RE (RE=Gd, Er) and Ti atoms lose charges while Si obtain charges. From the analysis of the density of states for the RE2Ti3Si4 (RE=Gd, Tb, Er) compounds, we can make the conclusion that Si mainly contributes to the bonding states, while Ti and RE contribute to the anti-bonding states. RE atoms exhibit strong magnetism, Ti atoms exhibit different magnetic strength in different compounds, while Si is non-magnetic because all the subshells are completely occupied by the majority and minority spin. In order to obtain believable magnetic moments, we revised our calculated results and realized expected values.

Site Preference of Rare Earth Doping in Palladium‐Iron‐Arsenide Superconductors

AbstractThe solid solutions (Ca1–yREyFe1–xPdxAs)10PdzAs8 with RE = La, Ce, and Pr were synthesized by solid state methods and characterized by X‐ray powder diffraction with subsequent Rietveld refinements [(CaFeAs)10Pt3As8‐type structure (“1038 type”), P$\bar{1}$, Z = 1]. Substitution levels (Ca/RE, Fe/Pd, and Pd/□) obtained from Rietveld refinements coincide well with the nominal values according to EDS and the linear courses of the lattice parameters as expected from the ionic radii. The RE atoms favor the one out of five calcium sites, which is eightfold coordinated by arsenic. This leads to significant stabilization of the structure, and especially prevents palladium over‐doping in the iron‐arsenide layers as observed in the pristine compound (CaFe1–xPdxAs)10PdzAs8. While the stabilization energy is estimated to about 40 kJ·mol–1 by electronic structure calculations, the reason for the diminished Fe/Pd substitution through RE doping is still not yet understood. We suggest that the electrons transferred from RE3+ to the (Fe1–xPdx)As layer makes higher palladium concentrations unfavorable. Anyway the reduced palladium doping enables superconductivity with critical temperatures up to 20 K (onset) in the RE doped Pd1038 samples, which could not be obtained earlier due to palladium over‐doping in the active iron‐arsenide layers.

Manganese-substituted rare-earth zinc arsenides RE(1-y)Mn(x)Zn(2-x)As2 (RE = Eu-Lu) and RE(2-y)Mn(x)Zn(4-x)As4 (RE = La-Nd, Sm, Gd).

Two series of Mn-substituted rare-earth zinc arsenides RE(1-y)Mn(x)Zn(2-x)As2 (RE = Eu-Lu) and RE(2-y)Mn(x)Zn(4-x)As4 (RE = La-Nd, Sm, Gd) were prepared by reaction of the elements at 750 °C. Both series are derived from ideal empirical formula REM2As2 (M = Mn, Zn) and adopt crystal structures related to the trigonal CaAl2Si2-type (space group P3m1) in which hexagonal nets of RE atoms and [M2As2] slabs built up of edge-sharing M-centered tetrahedra are alternately stacked along the c-direction. For compounds with divalent RE components (Eu, Yb), the fully stoichiometric and charge-balanced formula REM2As2 is obtained, with Mn and Zn atoms statistically disordered within the same tetrahedral site. For compounds with trivalent RE components, the RE sites become deficient, and the Mn atoms are segregated from the Zn atoms in separate tetrahedral sites. Within the series RE(1-y)Mn(x)Zn(2-x)As2 (Gd-Tm, Lu), the parent CaAl2Si2-type structure is retained, and the Mn atoms are disordered within partially occupied interstitial sites above and below [Zn(2-x)As2] slabs. Within the series RE(2-y)Mn(x)Zn(4-x)As4 (RE = La-Nd, Sm, Gd), the c-axis becomes doubled as a result of partial ordering of Mn atoms between every other pair of [Zn(2-x)As2] slabs. Attempts to synthesize Gd-containing solid solutions with the charge-balanced formula Gd0.67Mn(x)Zn(2-x)As2 suggested that these phases could be formed with up to 50% Mn substitution. Band structure calculations reveal that a hypothetical superstructure model with the formula La1.33MnZn3As4 would have no gap at the Fermi level and that slightly lowering the electron count alleviates antibonding Mn-As interactions; a spin-polarized calculation predicts nearly ferromagnetic half-metallic behavior. X-ray photoelectron spectroscopy confirms the presence of divalent Mn in these compounds.

A study of defects in iron-based binary alloys by the Mössbauer and positron annihilation spectroscopies

The room temperature positron annihilation lifetime spectra and 57Fe Mössbauer spectra were measured for pure Fe as well as for iron-based Fe1−xRex, Fe1−xOsx, Fe1−xMox, and Fe1−xCrx solid solutions, where x is in the range between 0.01 and 0.05. The measurements were performed in order to check if the known from the literature, theoretical calculations on the interactions between vacancies and solute atoms in iron can be supported by the experimental data. The vacancies were created during formation and further mechanical processing of the iron systems under consideration so the spectra mentioned above were collected at least twice for each studied sample synthesized in an arc furnace— after cold rolling to the thickness of about 40 μm as well as after subsequent annealing at 1270 K for 2 h. It was found that only in Fe and the Fe-Cr system the isolated vacancies thermally generated at high temperatures are not observed at the room temperature and cold rolling of the materials leads to creation of another type of vacancies which were associated with edge dislocations. In the case of other cold-rolled systems, positrons detect vacancies of two types mentioned above and Mössbauer nuclei “see” the vacancies mainly in the vicinity of non-iron atoms. This speaks in favour of the suggestion that in iron matrix the solute atoms of Os, Re, and Mo interact attractively with vacancies as it is predicted by theoretical computations and the energy of the interaction is large enough for existing the pairs vacancy-solute atom at the room temperature. On the other hand, the corresponding interaction for Cr atoms is either repulsive or attractive but smaller than that for Os, Re, and Mo atoms. The latter is in agreement with the theoretical calculations.

Hydrodeoxygenation of guaiacol over ReS2/activated carbon catalysts. Support and Re loading effect

Two activated carbons (GAC and CGran Norit) were used as supports to prepare Re/C catalysts (0.4 atoms of Re per nm2 of support). In addition, Re(x)/GAC catalysts with loadings of 0.5, 0.6, 0.7 and 0.8 atoms of Re per nm2 of support were prepared. The activity difference between Re(0.4)/CGran and Re(0.4)/GAC catalysts was related to the amount of surface oxygen functional groups on the support that is resistant to sulfidation. Meanwhile, the activity of the Re(x)/GAC catalysts as a function of Re content was correlated with ReS2 dispersion; the most active catalyst was the one with Re loading of 0.6 atoms per nm2 of support. On the other hand, the selectivity, expressed in terms of the phenol/catechol ratio, did not change with Re loading but was rather mainly influenced by the acid strength of the support.

In situ formation of RE2S3 and RE2O2S phases on sinter skin of Cr–mischmetal co-doped WC—Co alloy

The as-sintered sinter skin of WC—11Co—0.71Cr3C2—0.06RE cemented carbide with WC+β microstructure was analyzed by scanning electron microscope, energy dispersive X-ray spectroscope and X-ray diffractometer. RE represents La-, Ce-, Pr- and Nd-containing mischmetal, and β is cobalt-based binder phase. It was discovered that La, Ce, Pr and Nd migrated directionally from the alloy to the sinter skin to combine with the impurity elements S and O from the sintering atmosphere during the sintering process. As a result, main dispersed phase RE2S3 and minor RE2O2S were formed in situ on the sinter skin. The mechanisms for the stimulation of the migration activity and the directional migration of RE atoms were discussed in terms of the thermodynamics stability of Cr3C2, solubility characteristic of Cr in Co and the polarization or ionization of RE atoms.

Nanostructure evolution and mechanical properties of rapidly solidified Al3Ni3RE (Y, Ce) alloys

The melt spun and subsequently annealed Al3Ni3RE (Y, Ce) alloys with the composition of Al88Ni6Y6, Al86Ni6Y8, Al86Ni6Y6Ce2 and Al84Ni6Y6Ce4 (at%) were investigated through differential scanning calorimetry (DSC), transmission electron microscopy (TEM), X-ray diffraction and nanoindentation. The influence of RE (Y, Ce) elements on the thermal stability and mechanical properties of Al3Ni3RE alloys have been studied. The glass forming ability, thermal stability and hardness value have been increased with substitution of Al atoms by RE atoms. TEM analysis confirm that the structure consists of α-Al nanoparticles embedded in an amorphous matrix produced by non-isothermal annealing of initially fully amorphous Al86Ni6Y6Ce2 ribbons. Significant changes in hardness value occur due to changes of both chemical composition and crystalline structure. The maximum hardness of 7.30±0.58GPa is obtained in the Al86Ni6Y6Ce2 alloy by annealing at 618K with a mixed microstructure of fine Al nanoparticles and nano-Al3Ni intermetallic compound in an amorphous matrix.

The role of rare earth elements in zeolites and cracking catalysts

This brief review has the objective of showing the role of the rare earth in the context of Fluid Catalytic Cracking (FCC). REHY and RENaY zeolites, two of the most important components of FCC catalysts, were extensively studied in the past years. Their properties were evaluated in different conditions and the discussions of their main characteristics were revisited. It has been shown that RE elements migrate to smaller cages upon calcination and, once located in these cages, they form bridges with framework oxygen atoms, stabilising the zeolite structure. Some hydrolysis reactions take place over RE cations, generating Brønsted acidity and the higher the ionic radius of the RE atom, the higher the degree of hydrolysis. Besides, a correlation between the ionic radius of the RE atom, the Brønsted acidity of the zeolite and the rate of hydrogen transfer reaction was observed. Also, the use of rare earth elements as a vanadium trap has been analysed. Finally, new applications of rate earth containing zeolites in other fields than FCC catalysis indicate that this subject is still a matter of great interest.

Quaternary Germanides RE4Mn2InGe4 (RE = La–Nd, Sm, Gd–Tm, Lu)

The quaternary germanides RE4Mn2InGe4 (RE = La-Nd, Sm, Gd-Tm, Lu) have been prepared by arc-melting reactions of the elements and annealing at 800 °C and represent the second example of the RE4M2InGe4 series previously known only for M = Ni. Single-crystal X-ray diffraction studies conducted on the earlier RE members of RE4Mn2InGe4 confirmed that they adopt the monoclinic Ho4Ni2InGe4-type structure [space group C2/m, a = 16.646(2)-15.9808(9) Å, b = 4.4190(6)-4.2363(2) Å, c = 7.4834(10)-7.1590(4) Å, β = 106.893(2)-106.304(1)° in the progression of RE from La to Gd]. The covalent framework contains Mn-centered tetrahedra and Ge2 dimers that build up [Mn2Ge4] layers, which are held weakly together by four-coordinate In atoms and outline tunnels filled by the RE atoms. This bonding picture is supported by band-structure calculations. An alternative description based on Ge-centered trigonal prisms reveals that RE4Mn2InGe4 is closely related to RE2InGe2. The electrical resistivity behavior of Pr4Mn2InGe4 is similar to that of Pr2InGe2.

New high pressure rare earth tantalates RExTa2O5+1.5x (RE=La, Eu, Yb)

Abstract Rare earth tantalates La0.075Ta2O5.113, Eu0.089Ta2O5.134 and Yb0.051Ta2O5.077 have been prepared by solid state reaction at P=7.0 GPa and T=1050–1100 °C and studied by X-ray diffraction, thermal analysis and electron microscopy. Low hydrated amorphous tantalum, lanthanum, europium and ytterbium hydroxides were used as starting materials. Aqueous as well as anhydrous compounds were obtained. Title tantalates are crystallized in the structure type of F–Ta2O5 [Zibrov et al. Russ. J. Inorg. Chem. 48 (2003) 464–471] [5] . The structure was refined by the Rietveld method from X-ray powder diffractometer data: La0.075Ta2O5.113, a=10.5099(2), b=7.2679(1), c=6.9765(1) A, V=532.90(1) A3, Z=6, space group Ibam; Eu0.089Ta2O5.134, a=10.4182(3), b=7.2685(1), c=6.9832(1) A, V=528.80(2) A3, Z=6, space group Ibam; Yb0.051Ta2O5.077, a=10.4557(2), b=7.3853(1), c=6.8923(1) A, V=532.21(1) A3, Z=6, space group Ibam. RE atoms do not replace the tantalum in its positions but the only water in the channels of the structure. Highly charged cations RE+3 compress the unit cell so that its volume becomes less than that of F–Ta2O5. Significant decrease of the unit cell volume after water removal from the structure is possible due to the puckering of pentagonal bipyramid layers and change of the corrugation angle in the layer.

Ternary rare-earth ruthenium and iridium germanides RE3M2Ge3 (RE=Y, Gd–Tm, Lu; M=Ru, Ir)

Through arc-melting reactions of the elements and annealing at 800 °C, the ternary rare-earth germanides RE 3 Ru 2 Ge 3 and RE 3 Ir 2 Ge 3 have been prepared for most of the smaller RE components ( RE =Y, Gd–Tm, Lu). In the iridium-containing reactions, the new phases RE 2 IrGe 2 were also generally formed as by-products. Powder X-ray diffraction revealed orthorhombic Hf 3 Ni 2 Si 3 -type structures (space group Cmcm , Z =4) for RE 3 M 2 Ge 3 ( M =Ru, Ir) and monoclinic Sc 2 CoSi 2 -type structures (space group C 2/ m , Z =4) for RE 2 IrGe 2 . Full crystal structures were determined by single-crystal X-ray diffraction for all members of RE 3 Ru 2 Ge 3 ( a =4.2477(6) Å, b =10.7672(16) Å, c =13.894(2) Å for RE =Y; a =4.2610(3)–4.2045(8) Å, b =10.9103(8)–10.561(2) Å, c =14.0263(10)–13.639(3) Å in the progression of RE from Gd to Lu) and for Tb 3 Ir 2 Ge 3 ( a =4.2937(3) Å, b =10.4868(7) Å, c =14.2373(10) Å). Both structures can be described in terms of CrB- and ThCr 2 Si 2 -type slabs built from Ge-centred trigonal prisms. However, band structure calculations on Y 3 Ru 2 Ge 3 support an alternative description for RE 3 M 2 Ge 3 based on [ M 2 Ge 3 ] layers built from linked M Ge 4 tetrahedra, which emphasizes the strong M –Ge covalent bonds present. The temperature dependence of the electrical resistivity of RE 3 Ru 2 Ge 3 generally indicates metallic behaviour but with low-temperature transitions visible for some members ( RE =Gd, Tb, Dy) that are probably associated with magnetic ordering of the RE atoms. Anomalously, Y 3 Ru 2 Ge 3 exhibits semiconductor-like behaviour of uncertain origin. Magnetic measurements on Dy 3 Ru 2 Ge 3 reveal antiferromagnetic ordering at 3 K and several unusual field-dependent transitions suggestive of complex spin reorientation processes. RE 3 M 2 Ge 3 ( M =Ru, Ir) adopts the Hf 3 Ni 2 Si 3 -type structure containing slabs built up from Ge-centred trigonal prisms. • Crystal structures of RE 3 Ru 2 Ge 3 ( RE =Y, Gd–Tm, Lu) and Tb 3 Ir 2 Ge 3 were determined. • Strong M –Ge covalent bonds were confirmed by band structure calculations. • Most RE 3 Ru 2 Ge 3 members except Y 3 Ru 2 Ge 3 exhibit metallic behaviour. • Dy 3 Ru 2 Ge 3 displays unusual field-dependent magnetic transitions.

Hydrogen absorption in RE2T2In compounds

• Hydrogenation on selected RE 2 T 2 X was performed. • Nd 2 Ni 2 In is unique among “221” compounds, exhibiting a very high H absorption. • The behavior found in RE 2 Ni 2 In changes when replacing Ni for Pd. • The amorphization of La 2 Pd 2 In allows to go up to 4.6 H/f.u. • RE 2 Pd 2 In with heavy RE can absorb 2 H/f.u. without structure distortion. RE 2 T 2 In compounds (RE = rare earth, T is a late transition metal) were found, depending on the composition, absorbing different amounts of H. Several types of reaction of crystal structure have been found. Mere volume expansion, analogous to U 2 T 2 X compounds, was found e.g. in Tb 2 Pd 2 In, allowing to accommodate up to 2 H atoms/f.u. (one formula unit comprises 2 RE atoms). More dramatic structure modifications are required, to keep the H–H spacing higher than 2.1 Å, for higher H absorption. One type of reaction is amorphization, observed in La 2 Pd 2 In. Other type was observed in Nd 2 Ni 2 In, undergoing an orthorhombic distortion and forming four different H sites. The volume expansion exceeds 23%.

Rare-earth rich indides RE8CoIn3 (RE = Y, Dy–Tm, Lu)

New ternary indides RE8CoIn3 (RE = Y, Dy–Tm, Lu) have been prepared by arc-melting and subsequent annealing at T = 870 K. The crystal structures have been studied using X-ray powder diffraction. The RE8CoIn3 indides are isotypic with Pr8CoGa3, space group P63mc, Pearson code hP24: a = 10.3678(2), c = 7.0069(2) Å for Y8CoIn3; a = 10.3370(4), c = 6.9246(3) Å for Dy8CoIn3; a = 10.2856(2), c = 6.9030(2) Å for Ho8CoIn3; a = 10.2374(2), c = 6.8759(2) Å for Er8CoIn3; a = 10.1863(2), c = 6.8461(2) Å for Tm8CoIn3; a = 10.1168(4), c = 6.7977(4) Å for Lu8CoIn3. The coordination polyhedra of the RE atoms have 12-, 13- and 14-vertices. The polyhedron around the Co atom is an octahedron with one additional atom, and around the In atoms it is a strongly distorted trigonal prism with five additional atoms.

The effect of Ga‐doping on the defect chemistry of RE3Al5O12 garnets

AbstractIt has been recently shown that the addition of Ga to Lu3Al5O12 garnet (LuAG) removes the electron trapping associated with cation antisite defects. In this paper, we show via atomic scale simulations that the replacement of Al with Ga in LuAG actually lowers the energy of the antisite disorder process. Thus, we predict that Ga additions will lead to an increase of the antisite defect concentration and, in the absence of the electronic structure changes, would actually degrade the performance of the material. Since there are two crystallographically distinct Al sites in the garnet structure, we not only present results for complete replacement of Al with Ga, but also partial replacement for 40% (on 16a) and 60% (on 24d) of the Al with Ga. Our results support the explanation for Ga‐doping leading to improvement in garnet scintillator performance that relies on variations of the electronic structure rather than reduction of the antisite defect concentration. magnified imageCation antisite defects in RE3Al5O12 garnet, where small light gray atoms and large dark gray atoms are lattice Al and RE atoms, respectively. The constituents of the antisite defect pairs are labeled, and it should be noted that the Ga atom (blue) is similar in size to RE (green). Oxygen atoms are not shown for clarity.