Search

Pseudobinary Gd5(Si,Ge)4 compounds show a giant magnetocaloric effect due to an intriguing structure-magnetism interplay. Here, we report a high resolution transmission electron microscopic study of microstructure in a melt-grown compound of Gd5Si1.5Ge2.5. Electron diffraction showed that mesoscopic microstructure of the compound consists of crystals of a monoclinic structure and two kinds of orthorhombic structure. However, atomic-level imaging revealed a coexistence of mosaic-like nanodomains of these structures in each crystal. The nanodomains have twin-like interfaces along the b axis of the crystal but have semicoherent interfaces along a perpendicular axis due to stacking faults. Such a nanoscale structural heterogeneity is due to covalent bond-controlled phase separation at elevated temperatures. This finding offers insights into phase relations and abnormal magnetic behavior of Gd5(Si,Ge)4 compounds and points out a route of synthesizing bulk nanocomposites via nanoscale phase separation.

To understand the effect of selenium doping on the good cycling performance and rate capability of a Ge0.9Se0.1 electrode, the dynamic morphological and phase changes of the Ge0.9Se0.1 electrode were investigated by synchrotron-based operando transmission X-ray microscopy (TXM) imaging, X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The TXM results show that the Ge0.9Se0.1 particle retains its original shape after a large volume change induced by (de)lithiation and undergoes a more sudden morphological and optical density change than pure Ge. The difference between Ge0.9Se0.1 and Ge is attributed to a super-ionically conductive Li–Se–Ge network formed inside Ge0.9Se0.1 particles, which contributes to fast Li-ion pathways into the particle and nano-structuring of Ge as well as buffering the volume change of Ge. The XRD and XAS results confirm the formation of a Li–Se–Ge network and reveal that the Li–Se–Ge phase forms during the early stages of lithiation and is an inactive phase. The Li–Se–Ge network also can suppress the formation of the crystalline Li15Ge4 phase. These in situ and operando results reveal the effect of the in situ formed, super-ionically conductive, and inactive network on the cycling performance of Li-ion batteries and shed light on the design of high capacity electrode materials.

The electronic excitation of 3d transition metal oxide depends on the hybridization between orbitals of different ions, and is related to the materials properties. In this work, we systematically study the effect of hydrostatic pressure up to ∼20 GPa on the crystal structure and electronic structure of Pr0.67Sr0.33MnO3 powder, using Mn K-edge X-ray absorption near edge structure and X-ray diffraction at room temperature. With the increase of pressure, the energy position of non-local screened feature moves towards feature without screening due to the enhanced transition energy; however, the intensity (probability) of non-local screened feature increases with the pressure. Further study suggests that the pressure-induced antiferromagnetic phase, affecting hybridization between neighboring Mn ions with spin sensitivity, increase the probability of non-local charge transfer and corresponding intensity of non-local screened feature. The spin-sensitivity of non-local screening may be a useful parameter for characterization of material properties.

Batteries with conversion-type electrodes exhibit higher energy storage density but suffer much severer capacity fading than those with the intercalation-type electrodes. The capacity fading has been considered as the result of contact failure between the active material and the current collector, or the breakdown of solid electrolyte interphase layer. Here, using a combination of synchrotron X-ray absorption spectroscopy and in situ transmission electron microscopy, we investigate the capacity fading issue of conversion-type materials by studying phase evolution of iron oxide composited structure during later-stage cycles, which is found completely different from its initial lithiation. The accumulative internal passivation phase and the surface layer over cycling enforce a rate−limiting diffusion barrier for the electron transport, which is responsible for the capacity degradation and poor rate capability. This work directly links the performance with the microscopic phase evolution in cycled electrode materials and provides insights into designing conversion-type electrode materials for applications., Conversion electrodes possess high energy density but suffer a rapid capacity loss over cycling compared to their intercalation equivalents. Here the authors reveal the microscopic origin of the fading behavior, showing that the formation and augmentation of passivation layers are responsible.

Nickel-rich transition-metal (TM) layered oxides, particularly those with high Ni content, attract worldwide interest for potential use as high-capacity cathodes in next-generation Li-ion batteries. However, as Ni loading increases, Li and Ni sitting at octahedra tend to mix, resulting in reduced electrochemical activity, which has been one major obstacle to their practical applications. Herein, we investigate the kinetic and thermodynamic aspects of Li/Ni mixing in LiNi0.7MnxCo0.3–xO2 (0 ≤ x ≤ 0.3) as they are synthesized, through quantitative determination of structural ordering and comparison to ab initio calculations. Results from this study elucidate the role of Co/Mn-substitution in tuning Li/Ni ordering, intrinsically through local magnetic interaction. Specifically, Co substitution facilitates Li/Ni ordering by relieving the intra-plane magnetic frustration and reducing the inter-plane super-exchange (SE) interaction; in contrast, Mn exacerbates magnetic frustration and strengthens SE, thereby agg...

Anionic redox in positive electrode materials in Li-ion batteries provides an additional redox couple besides conventional metal redox, which can be harvested to further boost the energy density of current Li-ion batteries. However, the requirement for the reversible anionic redox activity remains under debate, hindering the rational design of new materials with reversible anionic redox. In this work, we employed differential electrochemical mass spectrometry (DEMS) to monitor the release of oxygen and to quantify the reversibility of the anionic redox of Li2Ru0.75M0.25O3 (M = Ti, Cr, Mn, Fe, Ru, Sn, Pt, Ir) upon first charge. X-ray absorption spectroscopy, coupled with density functional theory (DFT) calculations, show that various substituents have a minimal effect on the nominal metal redox, yet more ionic substituents and reduced metal-oxygen covalency introduce irreversible oxygen redox, accompanied with easier distortion of the M-O octahedron and a smaller barrier for forming an oxygen dimer within the octahedron. Therefore, a strong metal-oxygen covalency is needed to enhance the reversible oxygen redox. We proposed an electron-phonon-coupled descriptor for the reversibility of oxygen redox, laying the foundation for high-throughput screening of novel materials that enable reversible anionic redox activity. This journal is

The effect of magnetic fields on the local structure of the Fe81Ga19 alloy was investigated by X-ray absorption fine spectroscopy (XAFS) technique. The results demonstrate that 0.6 T magnetic fields lead to the increasing of the 3d, 4s and 4p electrons of Fe atoms, but the decreasing of the 4p electrons of Ga atoms. The electron transfer from Ga to Fe with applying magnetic fields is revealed. The magnetic fields increase the Fe–Ga bond length. The role of the Fe–Ga bond in determining the magnetostriction is revealed.

The transformation from crystalline SrIrO3 to active amorphous iridium oxide electrocatalyst occurs via the lattice oxygen redox., The use of renewable electricity to prepare materials and fuels from abundant molecules offers a tantalizing opportunity to address concerns over energy and materials sustainability. The oxygen evolution reaction (OER) is integral to nearly all material and fuel electrosyntheses. However, very little is known about the structural evolution of the OER electrocatalyst, especially the amorphous layer that forms from the crystalline structure. Here, we investigate the interfacial transformation of the SrIrO3 OER electrocatalyst. The SrIrO3 amorphization is initiated by the lattice oxygen redox, a step that allows Sr2+ to diffuse and O2− to reorganize the SrIrO3 structure. This activation turns SrIrO3 into a highly disordered Ir octahedral network with Ir square-planar motif. The final SryIrOx exhibits a greater degree of disorder than IrOx made from other processing methods. Our results demonstrate that the structural reorganization facilitated by coupled ionic diffusions is essential to the disordered structure of the SrIrO3 electrocatalyst.

This paper reports a comparative study of the magnetization, magnetocaloric effects, and crystal lattices of an as-cast sample and an annealed sample of the CoMnSi compound. Magnetic measurements showed that the annealed sample has high magnetization and a doubled maximum magnetic entropy change with respect to the as-cast sample. X-ray diffraction studies determined that both samples crystallize into an orthorhombic lattice. However, there are remarkable differences in the lattice parameters and one of the nearest Mn–Mn distances between the samples. Spectroscopic measurements of the X-ray absorption near-edge structure revealed that Co–Si bonds of the annealed sample are shorter than those of the as-cast sample due to stronger ${p}$ – ${d}$ hybridization of Co and Si atoms, while other chemical bonds do not show any difference. It is concluded that high-temperature annealing enhances ferromagnetic interactions in the lattice of CoMnSi by chemical ordering of Co atoms.

Solid-state ion shuttles are of broad interest in electrochemical devices, nonvolatile memory, neuromorphic computing, and biomimicry utilizing synthetic membranes. Traditional design approaches are primarily based on substitutional doping of dissimilar valent cations in a solid lattice, which has inherent limits on dopant concentration and thereby ionic conductivity. Here, we demonstrate perovskite nickelates as Li-ion shuttles with simultaneous suppression of electronic transport via Mott transition. Electrochemically lithiated SmNiO 3 (Li-SNO) contains a large amount of mobile Li + located in interstitial sites of the perovskite approaching one dopant ion per unit cell. A significant lattice expansion associated with interstitial doping allows for fast Li + conduction with reduced activation energy. We further present a generalization of this approach with results on other rare-earth perovskite nickelates as well as dopants such as Na + . The results highlight the potential of quantum materials and emergent physics in design of ion conductors.

Lithium cobalt oxides (LiCoO2) possess a high theoretical specific capacity of 274 mAh g–1. However, cycling LiCoO2-based batteries to voltages greater than 4.35 V versus Li/Li+ causes significant structural instability and severe capacity fade. Consequently, commercial LiCoO2 exhibits a maximum capacity of only ~165 mAh g–1. Here, we develop a doping technique to tackle this long-standing issue of instability and thus increase the capacity of LiCoO2. La and Al are concurrently doped into Co-containing precursors, followed by high-temperature calcination with lithium carbonate. The dopants are found to reside in the crystal lattice of LiCoO2, where La works as a pillar to increase the c axis distance and Al as a positively charged centre, facilitating Li+ diffusion, stabilizing the structure and suppressing the phase transition during cycling, even at a high cut-off voltage of 4.5 V. This doped LiCoO2 displays an exceptionally high capacity of 190 mAh g–1, cyclability with 96% capacity retention over 50 cycles and significantly enhanced rate capability. Lithium cobalt oxides are used as a cathode material in batteries for mobile devices, but their high theoretical capacity has not yet been realized. Here, the authors present a doping method to enhance diffusion of Li ions as well as to stabilize structures during cycling, leading to impressive electrochemical performance.

The rare negative thermal expansion (NTE) in ferroelectrics has received significant attention in lead-titanate perovskite oxides. Recently, a notable NTE of −4.7(1) × 10–5 K–1 was reported in a lead-free and nonperovskite ferroelectric Sn2P2S6. The stereochemically active lone-pair of Sn(II) was considered to be responsible for the NTE. Here, the role of the lone-pair is further explored via substitution of Ge(II)/Pb(II) for the cation Sn(II). Both high-energy as well as high-resolution synchrotron X-ray diffraction were employed to reveal the tailored NTE behavior and structure evolution, respectively. Due to the stereochemically inactive Pb(II) 6s2 pair when bonding with anion sulfur, the Pb(II)-substitution depresses the ferroelectricity and reduces the NTE of Sn2P2S6 to –1.9(2) × 10–5/K in (Sn0.85Pb0.15)P2S6. However, for (Sn0.975Ge0.025)P2S6, the ferroelectricity is enhanced by the tiny amount of stereochemically active Ge(II) 4s2 pair but the NTE is weakened to –3.9(1) × 10–5/K. The Raman spectra h...

The polarization of $\mathrm{PbZ}{\mathrm{r}}_{0.52}\mathrm{T}{\mathrm{i}}_{0.48}{\mathrm{O}}_{3}$ thin film is switched by changing film thickness through the competition between the strain relaxation-induced flexoelectric fields and the interfacial effects. Without an applied electric field, this reversal of polarization is exploited to control the magnetic properties of $\mathrm{L}{\mathrm{a}}_{0.67}\mathrm{S}{\mathrm{r}}_{0.33}\mathrm{Mn}{\mathrm{O}}_{3}$ by the competition/cooperation between the charge-mediated and the strain-mediated effects. Scanning transmission electron microscopy, polarized near-edge x-ray absorption spectroscopy, and half-integer diffraction measurements are employed to decode the intrinsic magnetoelectric effects in the $\mathrm{L}{\mathrm{a}}_{0.67}\mathrm{S}{\mathrm{r}}_{0.33}\mathrm{Mn}{\mathrm{O}}_{3}/\mathrm{PbZ}{\mathrm{r}}_{0.52}\mathrm{T}{\mathrm{i}}_{0.48}{\mathrm{O}}_{3}$ heterostructures. With $\mathrm{PbZ}{\mathrm{r}}_{0.52}\mathrm{T}{\mathrm{i}}_{0.48}{\mathrm{O}}_{3}$ films $l48\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$, the polarization-driven carrier density modulation around the $\mathrm{L}{\mathrm{a}}_{0.67}\mathrm{S}{\mathrm{r}}_{0.33}\mathrm{Mn}{\mathrm{O}}_{3}/\mathrm{PbZ}{\mathrm{r}}_{0.52}\mathrm{T}{\mathrm{i}}_{0.48}{\mathrm{O}}_{3}$ interface and the strain-mediated Mn $3d$ orbital occupancy work together to enhance the magnetism of 14-unit-cell $\mathrm{L}{\mathrm{a}}_{0.67}\mathrm{S}{\mathrm{r}}_{0.33}\mathrm{Mn}{\mathrm{O}}_{3}$ film; with $\mathrm{PbZ}{\mathrm{r}}_{0.52}\mathrm{T}{\mathrm{i}}_{0.48}{\mathrm{O}}_{3}$ layers $g48\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$, the strain-induced change of bond length/angle of $\mathrm{Mn}{\mathrm{O}}_{6}$ accompanied with a modified spin configuration are responsible for the decrease in the Curie temperature and magnetization of 14-unit-cell $\mathrm{L}{\mathrm{a}}_{0.67}\mathrm{S}{\mathrm{r}}_{0.33}\mathrm{Mn}{\mathrm{O}}_{3}$ film.

Anion redox in lithium transition metal oxides such as Li(2)RuO(3) and Li(2)MnO(3,) has catalyzed intensive research efforts to find transition metal oxides with anion redox that may boost the energy density of lithium-ion batteries. The physical origin of observed anion redox remains debated, and more direct experimental evidence is needed. In this work, we have shown electronic signatures of oxygen-oxygen coupling, direct evidence central to lattice oxygen redox (O(2−)/(O(2))(n−)), in charged Li(2-x)RuO(3) after Ru oxidation (Ru(4+)/Ru(5+)) upon first-electron removal with lithium de-intercalation. Experimental Ru L(3)-edge high-energy-resolution fluorescence detected X-ray absorption spectra (HERFD-XAS), supported by ab-initio simulations, revealed that the increased intensity in the high-energy shoulder upon lithium de-intercalation resulted from increased O-O coupling, inducing (O-O) σ*-like states with π overlap with Ru d-manifolds, in agreement with O K-edge XAS spectra. Experimental and simulated O K-edge X-ray emission spectra (XES) further supported this observation with the broadening of the oxygen non-bonding feature upon charging, also originated from (O-O) σ* states. This lattice oxygen redox of Li(2-x)RuO(3) was accompanied by a small amount of O(2) evolution in the first charge from differential electrochemistry mass spectrometry (DEMS) but diminished in the subsequent cycles, in agreement with the more reduced states of Ru in later cycles from Ru L(3)-edge HERFD-XAS. These observations indicated that Ru redox contributed more to discharge capacities after the first cycle. This study has pinpointed the key spectral fingerprints related to lattice oxygen redox from a molecular level and constructed a transferrable framework to rationally interpret the spectroscopic features by combining advanced experiments and theoretical calculations to design materials for Li-ion batteries and electrocatalysis applications.

Crystal structure and magnetic properties of the quaternary Gd4Nd1Si2Ge2 compound were investigated using synchrotron X-ray diffraction and magnetic measurements. The compound crystallized into an orthorhombic structure in the temperature range 200–300 K. In zero field cooling, the compound undergoes a spin reorientation following a ferromagnetic-like transition at 276 K. The spin reorientation is hinted at by nonlinear changes of lattice parameters but is suppressed in a high magnetic field of 6 T. Magnetic measurements revealed a magnetocaloric effect with a high relative cooling power. It is suggested that Nd substitution for Gd enlarges magnetic anisotropy and induces a canted spin structure.

The cost of batteries is becoming as important as the energy density for large-scale electrochemical energy storage application. Sodium manganese-rich layered oxides (P-type and O-type) are thus one of the promising cathode materials for rechargeable batteries because of the relatively low cost of manganese and sodium. The O-type cathodes are more promising for practical application owing to their high sodium-ion stoichiometry. However, most of these materials suffer from rapid capacity decay during high-voltage cycling. Herein, we used synchrotron X-ray probes coupled with electrochemical techniques to disclose the structural evolution of α-NaMnO2 during solid-state synthesis and electrochemical cycling. During high-voltage cycling, a substantial increase of interfacial microstrain from both stacking faults and Mn cation migration was found to pin down this material’s layered structures and simultaneously block the diffusion pathways of Na+, thus leading to the performance degradation. The findings prese...

The La(Fe, Si)13 compound shows a large magnetocaloric effect near room temperature. Partial substitution of Co for Fe can raise its Curie temperature and reduce the thermal hysteresis of its ferromagnetic transition. However, the influence of Co substitution on the crystal structure and magnetocaloric properties of La(Fe, Si)13 is not well understood yet. In this work, we report a comparative study of the crystal structure, magnetocaloric effects and elastic moduli of polycrystalline LaFe11.5Si1.5 and LaCoFe10.5Si1.5 samples using synchrotron radiation X-ray diffraction, magnetic measurements and resonant ultrasound spectroscopy. Compared to the Co-free sample, the Co-doped sample shows a sluggish ferromagnetic transition and reduced volumetric expansion as well as softer elastic moduli at room temperature. The Co-doped sample also shows stronger temperature dependence of Fe-Fe distances in its ferromagnetic state. Such differences between the samples are explained by considering the influence of Co doping on ferromagnetic interactions and lattice entropy.

We investigate doping- and pressure-induced changes in the electronic state of Mn $3d$ and As $4p$ orbitals in II-II-V-based diluted magnetic semiconductor $(\mathrm{B}{\mathrm{a}}_{1\ensuremath{-}x}{\mathrm{K}}_{x}){(\mathrm{Z}{\mathrm{n}}_{1\ensuremath{-}y}\mathrm{M}{\mathrm{n}}_{y})}_{2}\mathrm{A}{\mathrm{s}}_{2}$ to shed light into the mechanism of indirect exchange interactions leading to high ferromagnetic ordering temperature ($T\mathrm{c}=230\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ in optimally doped samples). A suite of x-ray spectroscopy experiments (emission, absorption, and dichroism) show that the emergence and further enhancement of ferromagnetic interactions with increased hole doping into the As $4p$ band is accompanied by a decrease in local $3d$ spin density at Mn sites. This is a result of increasing Mn $3d--\mathrm{As} 4p$ hybridization with hole doping, which enhances indirect exchange interactions between Mn dopants and gives rise to induced magnetic polarization in As $4p$ states. On the contrary, application of pressure suppresses exchange interactions. While Mn K $\ensuremath{\beta}$ emission spectra show a weak response of $3d$ states to pressure, clear As $4p$ band broadening (hole delocalization) is observed under pressure, ultimately leading to loss of ferromagnetism concomitant with a semiconductor to metal transition. The pressure response of As $4p$ and Mn $3d$ states is intimately connected with the evolution of the As-As interlayer distance and the geometry of the $\mathrm{MnA}{\mathrm{s}}_{4}$ tetrahedral units, which we probed with x-ray diffraction. Our results indicate that hole doping increases the degree of covalency between the anion (As) $p$ states and cation (Mn) $d$ states in the $\mathrm{MnA}{\mathrm{s}}_{4}$ tetrahedron, a crucial ingredient to promote indirect exchange interactions between Mn dopants and high $T\mathrm{c}$ ferromagnetism. The instability of ferromagnetism and semiconducting states against pressure is mainly dictated by delocalization of anion $p$ states.

Nickel-rich layered transition metal oxides, LiNi1-x (MnCo)x O2 (1-x ≥ 0.5), are appealing candidates for cathodes in next-generation lithium-ion batteries (LIBs) for electric vehicles and other large-scale applications, due to their high capacity and low cost. However, synthetic control of the structural ordering in such a complex quaternary system has been a great challenge, especially in the presence of high Ni content. Herein, synthesis reactions for preparing layered LiNi0.7 Mn0.15 Co0.15 O2 (NMC71515) by solid-state methods are investigated through a combination of time-resolved in situ high-energy X-ray diffraction and absorption spectroscopy measurements. The real-time observation reveals a strong temperature dependence of the kinetics of cationic ordering in NMC71515 as a result of thermal-driven oxidation of transition metals and lithium/oxygen loss that concomitantly occur during heat treatment. Through synthetic control of the kinetic reaction pathway, a layered NMC71515 with low cationic disordering and a high reversible capacity is prepared in air. The findings may help to pave the way for designing high-Ni layered oxide cathodes for LIBs.

Crystal structure and magnetic properties of Gd5Si1.5Ge2.5 and Gd4.9Zr0·1Si1.5Ge2.5 were investigated using high-energy X-ray diffraction and magnetic measurements. Results showed that a Zr substitution for 2% Gd reduces unit cell volumes of a room-temperature monoclinic and a low-temperature orthorhombic lattice and a difference between them at a magnetostructural transition. At a microscopic level, the Zr substitution increases length of disconnected interlayer T–T bonds of the monoclinic lattice at the expense of length of connected interlayer T–T bonds (T = Si, Ge). These opposing changes of the interlayer T–T bonds provided evidence for existence of a short-range chemical order of Ge atoms in lattices of Gd5Si1.5Ge2.5 and its weakening by the Zr substitution. Magnetic measurements revealed that the Zr substitution brings about a change of the magnetic structure and a reduction of a giant magnetocaloric effect of Gd5Si1.5Ge2.5. Based on such structural and magnetic changes due to the Zr substitution, we propose a relation between the short-range chemical order and the total entropy change at the magnetostructural transition. Using this relation, a giant magnetocaloric effect and an annealing effect observed over a wide range of Gd5(Si,Ge)4 composition can be explained quantitatively.

The participation of anion redox in lithium transition metal oxides such as Li2RuO3 and Li2MnO3 for positive electrodes have opened a new avenue to boost up the energy density of current lithium-ion batteries. There are many schools of thoughts for the physical origin proposed to be responsible for anion redox and more direct and clear experimental evidence of anion redox is needed to further understand and utilize this phenomena. In the first part of this work, we demonstrated the electronic signature of oxygen-oxygen coupling, direct evidence central to lattice oxygen redox (O2-/(O2)n-) in charged Li2-xRuO3 after Ru oxidation (Ru4+/Ru5+) upon first-electron removal with lithium de-intercalation. Experimental and simulated Ru L3-edge X-ray absorption spectra (XAS) revealed that the increase in the high-energy shoulder intensity upon lithium de-intercalation resulted from increased O-O coupling, inducing (O-O) σ* with π overlap with Ru d-manifolds, in agreement with the similar changes in the O K-edge XAS spectra. Further support came from experimental and simulated O K-edge X-ray emission spectra (XES), where the broadening of the oxygen nonbonding feature upon charging also originated from creation of (O-O) σ* states. By combining differential electrochemistry mass spectrometry (DEMS) with core-level spectroscopies, we are able to quantify the percentage of this lattice oxygen redox across different Li2RuxM(1-x)O3 (M=Ti, Cr, Mn, Fe, Ir, Sn) chemistries, through which we proposed a preliminary electronic descriptor for reversible bulk oxygen redox activity. This study constructed a transferrable framework to rationally interpret the spectroscopic features by combining experiments and theory, and pinpointed the key spectra footprints related to lattice oxygen redox from a molecular level. We also proposed a simple descriptor to rationalize and facilitate novel positive electrode materials design for reversible anion redox activities in high-energy Li-ion batteries.

We report a charge-transfer mechanism in tuning of magnetism of Nd-substituted Gd5-xNdxSi4 (x=1 and 2.5) compounds. The X-ray absorption near edge structure measurements demonstrated that Nd substitutions for Gd induce charge transfer of 5d electrons from Gd to Nd. The charge transfer weakens spin-orbital coupling of Gd but strengthens that of Nd. Consequently, the magnetization responses of the substituted compounds to low magnetic fields are increased while their saturation magnetization is reduced. Electronic structure calculations showed that the charge transfer stabilizes a ferromagnetic and a ferrimagnetic structure in the compounds with x = 1 and 2.5, respectively, but that it does not change the 5d-3p hybridization significantly. It is suggested that the charge transfer of 5d electrons may occur in other rare earth-substituted Gd5Si4 compounds allowing for tuning of their magnetism.