Rare Earth Substitution Research Articles

Chemical pressure exerted by rare earth substitution in BiFeO3: Effect on crystal symmetry, band structure and magnetism

Single phase BiFeO3 (BFO) is difficult to synthesize due to the volatile nature of Bi and the formation of impurity phases which restrict its use in commercial applications. Presence of free charge carriers in the system due to the formation of oxygen vacancies leads to an increase in the leakage current and suppresses intrinsic ferroelectric response of the system. In this paper, we present a detailed study of the structural phase transformation triggered by the substitution of rare-earth (RE) ions at A-site of BFO. We report that the chemical pressure induced by the substitutional ions stabilizes lower symmetry polymorphs. A detailed phase diagram showing connection between chemical pressure, ionic radii mismatch, dopant concentration and rare ions is also extracted on the basis of the structural analysis. Change in peak position and intensity of Raman vibrational modes and transformation of structure from rhombohedral to orthorhombic phase are identified to be a function of the concentration of RE ions substituted at the A-site. Five electronic transitions, two d-d and three charge transfer (CT) transitions, are observed in optical measurement within the spectral range of 1–5 eV. Shifts in d-d and CT transitions as a function of substitution are also observed. Dependence of the direct band gap on the concentration of substituent ion is also studied. Presence of spin spiral structure results in net cancellation of magnetic moments in BFO and, as a result, antiferromagnetic hysteresis loop is observed. Substitution of RE ions at A-sites induces chemical pressure which affects Fe-O-Fe bond angle and results in the destruction of spiral spin structure. Consequently, weak ferromagnetism is observed beyond certain concentration of RE in BFO.

Combined Study of Structural, Magnetic and Transport Properties of Eu0.5 Ln 0.5BiS2F Superconductor* *Supported by the National Natural Science Foundation of China (Grant No. 11704311), the Natural Science Foundation of Shaanxi Provincial Department of Education (Grant No. 17JK0772) and the Natural Science Foundation of Shaanxi Province (Grant No. 2018JQ1069)

Superconductivity below 0.3 K and a charge-density-wave-like (CDW-like) anomaly at 280 K were observed in EuBiS2F recently. Here we report a systematic study of structural and transport properties in Eu0.5Ln0.5BiS2F (Ln = La, Ce, Pr, Nd, Sm) by electrical resistivity, magnetization, and specific heat measurements. The lattice constants have a significant change upon rare earth substitution for Eu, suggesting an effective doping. As Ln is changed from Sm to La, the superconducting transition temperature T c increases from 1.55 K to 2.8 K. In contrast to the metallic parent compound, the temperature dependence of electrical resistivity displays semiconducting-like behavior for all the Eu0.5 Ln 0.5BiS2F samples. Meanwhile, the CDW-like anomaly observed in EuBiS2F is completely suppressed. Unlike the mixed valence state in the undoped compound, Eu ions in these rare-earth-doped samples are mainly divalent. A specific anomaly at 1.3 K resembling that in EuBiS2F suggests the coexistence of superconductivity and spin glass state for Eu0.5La0.5BiS2F. Coexistence of ferromagnetic order and superconductivity is found below 2.2 K in Eu0.5Ce0.5BiS2F samples. Our results supplies a rich diagram showing that many interesting properties can be induced in BiS2-based compounds.

Rare-earth indium selenides RE3InSe6 (RE = La−Nd, Sm, Gd, Tb): Structural evolution from tetrahedral to octahedral sites

The ternary rare-earth indium selenides RE3InSe6 have been prepared by reactions of the elements at 850 ​°C and the range of rare-earth substitution has been determined to be RE ​= ​La−Nd, Sm, Gd, Tb. Single crystals of La3InSe6, Ce3InSe6, and Nd3InSe6, obtained in the presence of KBr flux, were analyzed by X-ray diffraction, which revealed an orthorhombic structure in space group Pnnm with Z ​= ​4 and cell parameters of a ​= ​14.4722(18)−14.2793(11) Å, b ​= ​17.636(2)−17.4401(14) Å, and c ​= ​4.2123(5)−4.1013(3) Å. The structure consists of two types of linear stacks built from In-centred polyhedra, which are separated by the RE cations in seven and eightfold coordination. Careful examination of the In sites shows that there is a gradual evolution from the noncentrosymmetric La3InS6-type (space group P21212, adopted by most of the sulfides RE3InS6) to the centrosymmetric U3ScS6-type structure (space group Pnnm, adopted by most of the selenides RE3InSe6). Diffuse reflectance spectroscopy showed that all members of RE3InSe6 are semiconductors with optical band gaps of 1.2–1.4 ​eV. Magnetic measurements indicated that La3InSe6 is diamagnetic and Nd3InSe6 is paramagnetic with no transitions occurring down to 2 ​K.

Influence of strain-driven segregation in low-angle grain boundaries on critical current density of Y0.9Nd0.1Ba2Cu3O7-d

Low-angle grain boundaries (GBs) constitute the most important current-limiting mechanism in the operation of biaxially textured YBa2Cu3O7−d (YBCO)-coated conductors. Ca doping of YBCO is known to improve the critical current density J c across the GB because of carrier doping by anisovalent Ca2+ substitution for Y3+ and the strain relief induced by Ca segregation at the GB cores; however, the reduction of the superconducting critical temperature T c accompanying such doping is a marked drawback. Here we study the substitution of isovalent Nd3+ for Y3+ again using strain-driven segregation, in this case Nd3+, to improve J c without incurring significant T c reduction. Transport characteristics of low-angle GBs of 10% Nd-doped YBCO, Y0.9Nd0.1Ba2Cu3O7−d, grown on single crystal and 6° and 9° [001] tilt symmetric bicrystal SrTiO3 substrates are reported. It was found that J c across the 6° GB recovers to the intra-grain J c value in the 10% Nd-doped YBCO, while the 9° GB shows a modest J c enhancement compared to the pure YBCO 9° GB without a significant T c reduction. It is shown that the transparency of the GB could be enhanced without a large T c reduction by the isovalent substitution of rare-earth ions, suggesting new opportunities for cation segregation engineering in YBCO by isovalent rare-earth substitution.

Crystal chemistry and microfeatures of gadolinite imprinted by pegmatite formation and alteration evolution

AbstractGadolinite [REE2Fe2+Be2Si2O10] is a common mineral in certain types of rare element and rare earth element (REL-REE) pegmatites. Changes in pegmatite environment during and after gadolinite formation may be devised by studying its crystal-chemical properties and a thorough observation of microfeatures in the mineral matrix. Post-crystallization processes in pegmatite might trigger alteration mechanisms in gadolinite like in other REE-rich pegmatite minerals, whereby various late-magmatic or metasomatic events may affect mineral chemistry. Three gadolinite samples originating from various pegmatite occurrences in southern Norway offer an excellent opportunity in studying post-crystallization evolution of the pegmatites; by determining their crystallographic, chemical, and micro-textural features, imprints of the related processes in the pegmatites have been characterized in this study. Relevant mineral information was collected in recrystallization experiments of fully or slightly metamictized gadolinite samples and subsequent XRD analyses. Micro-Raman spectroscopy, electron microprobe analysis (EMPA), and scanning electron microscope–backscattered electron–energy-dispersive X-ray spectroscopy (SEM-BSE-EDS) analyses were employed to retrieve micro-chemical properties and related micro-textural features of the mineral matrix. With a reference to the gadolinite supergroup, a general alteration path can be envisaged outlining the pegmatite evolution and suggesting the occurrence of the secondary REE mineral phases: altered gadolinite domains prove Ca enrichment with a tendency toward the hingganite composition, while a slight fluorine increase and sporadic secondary fluorite occurrence imply a significant role of fluorine as a complexing agent in the dissolution-reprecipitation mechanism of metasomatic alteration in the mineral. Micro-Raman spectra show improved vibration statistics for the altered gadolinite domains, which could be linked to the substitution of rare earth elements (REE) by Ca and a possible increase of structural ordering within the gadolinite structure, being at the same time an indication of structural healing of metamictized domains by metasomatic processes. A study of microfeatures in the complex silicates like gadolinite proves to be an excellent tool to trace post-crystallization processes in a pegmatitic environment. With a slight redistribution of radionuclides during an alteration in gadolinite, a moderate precaution has to be taken when selecting gadolinite for U-Th-Pb dating.

Enhancement of the Thermal Stability and Thermoelectric Properties of Yb14MnSb11 by Ce Substitution

Yb14MnSb11 is a p-type high-temperature thermoelectric material with operational temperatures as high as 1273 K. Rare-earth (RE) substitution into this phase has been shown to increase the melting ...

Effect of rare-earth doping on adsorption of carbon atom on ferrum surface and in ferrum subsurface: A first-principles study

The adsorption of carbon atom on Fe surface and in Fe subsurface with and without rare earth (La and Ce) substitution in the surface layer and subsurface layer was studied by first-principles calculations. The carbon atom is predicted to adsorb at hollow and long bridge site on Fe(100) and Fe(110), respectively. However, the carbon atom shifts to occupy preferentially hollow site on both Fe(100) and Fe(110) with rare earth atom doping at surface layer. The lower adsorption energies involved with stronger adsorption abilities were obtained for carbon atoms on Fe surface with rare earth doping at surface layer, which was determined by the electronic structure of the surface atoms. The La atom was pulled out the surface after carbon adsorption due to strong interaction of La–C, which is consistent with the more charge transfer. In the subsurface region, the carbon atom prefers to occupy at octahedral site with rare earth doping at surface layer in Fe slab. These strong adsorption energies of the carbon atoms on Fe surface and in Fe subsurface with rare earth pose relevant insights into the interaction between carbon and rare earth, which helps to understanding the influence mechanism of rare earth in carburizing.

Weak ferromagnetism in perovskite oxides

Weak ferromagnetism has been widely found in antiferromagnetic systems, including the technically important orthorhombic perovskites $R\mathrm{Fe}{\mathrm{O}}_{3}$ ($R=\mathrm{rare}\phantom{\rule{0.16em}{0ex}}\mathrm{earth}$) owing to spin canting associated with crystal symmetry. Antisymmetric exchange interaction (AEI) and single-ion anisotropy (SIA) are the essential mechanisms responsible for the development of noncollinear structures in antiferromagnetic systems. AEI and SIA share the same structural restriction to facilitate the spin canting. While both AEI and SIA originate from the spin-orbit coupling effect, they have sharply different dependences on the local structure. Consideration of the structural dependence of a canted spin motivates us to revisit the orthoferrite family. The spin canting along the $c$ axis measured on precisely oriented crystals increases monotonically from $\mathrm{La}\mathrm{Fe}{\mathrm{O}}_{3}$ to $\mathrm{Lu}\mathrm{Fe}{\mathrm{O}}_{3}$. Based on Moriya's model, AEI is sensitive to the octahedral-site distortion in the perovskite structure. However, the site distortion does not exhibit a monotonic change with the rare-earth substitution. Instead, a linear relationship has been found in both the octahedral rotation and the spin canting angle versus the rare-earth ionic radius, which indicates that SIA plays a significant role leading the spin canting in orthoferrites.

FeCo Nanowire–Strontium Ferrite Powder Composites for Permanent Magnets with High-Energy Products

Due to the issues associated with rare-earth elements, there arises a strong need for magnets with properties between those of ferrites and rare-earth magnets that could substitute the latter in selected applications. Here, we produce a high remanent magnetization composite bonded magnet by mixing FeCo nanowire powders with hexaferrite particles. In the first step, metallic nanowires with diameters between 30 and 100 nm and length of at least 2 μm are fabricated by electrodeposition. The oriented as-synthesized nanowires show remanence ratios above 0.76 and coercivities above 199 kA/m and resist core oxidation up to 300 °C due to the existence of a >8 nm thin oxide passivating shell. In the second step, a composite powder is fabricated by mixing the nanowires with hexaferrite particles. After the optimal nanowire diameter and composite composition are selected, a bonded magnet is produced. The resulting magnet presents a 20% increase in remanence and an enhancement of the energy product of 48% with respect to a pure hexaferrite (strontium ferrite) magnet. These results put nanowire–ferrite composites at the forefront as candidate materials for alternative magnets for substitution of rare earths in applications that operate with moderate magnet performance.

SYNTHESIS AND CHARACTERIZATION OF RARE EARTH SUBSTITUTED M -TYPE (Sr-Ba) HEXAFERRITES

Effect of Rare earth elements (PrMn) substitution on the structural of Electrical and Dielectric properties Sr0.5-x Ba0.5PrxMnyFe12-yO19 (x =0.00–0.10; y =0.00–1.00) Hexaferrites prepared by sol–gel auto combustion is reported. The synthesized samples were characterized by Fourier Transform Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), AC and DC analysis. The XRD analysis confirmed the formation of single and double phase M-type Hexa-ferrite structures. The lattice parameters were found to be increasing as Rare earth (PrMn) contents were increasing, which is attributed to the ionic sizes of the implicated cations. The rare earth (PrMn) seems to be entirely soluble in the lattice. SEM revealed that the grain size decreased with increasing rare earth (PrMn) substitution. The coercivity values (780– 1077cm-1 ) of all sample lies in the range of M-type hexa-ferrite’s, which indicated that an increase of anisotropy was achieved by substitution of rare earth doping, while the size of particles drastically reduced from 10 to 1 µm. The increased anisotropy and fine particle size is useful for many applications such as improving signal noise ratio of recording devices.

Multiferroic and nanomechanical properties of Bi1−xRxFeO3 polycrystalline films (R = La, Pr, Sm, and Ho; x = 0–0.15)

We investigated phase constitutions, ferroelectric, magnetic, and nanomechanical characteristics of BiFeO3 films with rare-earth (R) substitution. Bi1−xRxFeO3 (R = La, Pr, Sm, and Ho; x = 0.05–0.15) thin film were prepared on the Pt buffered glass substrates by pulsed laser deposition. X-ray diffraction data indicated the occurrence of phase transition from rhombohedral structure to orthorhombic one in Bi1−xRxFeO3 thin films near x = 0.15, and an additional phase, Bi2Fe4O9, coexist for Bi1−xHoxFeO3 with x = 0–0.10. The studied BRFO polycrystalline films exhibit good ferroelectric and ferromagnetic properties at the same time. The remanent polarization (2Pr) of 77–164 μC/cm2 and electrical coercive field (Ec) of 310–493 kV/cm are obtained for BRFO films with R = La, Pr, Sm at x = 0.05–0.15 and R = Ho at x = 0.05. Good ferroelectric properties in BRFO films due to low leakage is highly related to phase constitution and interface morphology. Leakage mechanisms in BRFO films with various R and its contents x are also discussed. Besides, saturation magnetization (Ms) of 6.6–29.5 emu/cm3 and coercivity (Hc) of 125.0–549.4 Oe are obtained. The increased Ms with R and its contents x is related to the magnetic moment of the doped R3+ ion in addition to the suppressed spiral spin configuration. Finally, the hardness of 7.9–9.5 GPa for the BRFO films is found. The relationship between the hardness and grain size in good agreement with the Hall–Petch equation suggests the impeded propagation of dislocation by grain boundary mainly dominates the hardness. The result of this work indicates that the radius and magnetic moment of the R3+ ions plays a critical role in the structural evolution, refined microstructure, and therefore enhanced multiferroic and nanomechanical properties for rare-earth substituted BiFeO3 thin-film material systems.

Consequence of B-site substitution of rare earth (Gd+3) on electrical properties of manganese ferrite nanoparticles

Rare-earth-doped ferrite nanomaterials are known to show remarkable variation in structural, magnetic, and electrical behavior compared to their un-doped counterparts. In this report, low-temperature synthesis of Gd+3-doped manganese ferrite with composition MnFe2−xGdxO4 (x = 0.02, 0.04, 0.06, 0.08) has been represented. This report includes structural investigations done using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) and morphological analysis done through scanning electron microscopy (SEM). The compositional analysis was done through energy dispersive X-ray spectroscopy EDS. The variation of electrical properties like DC resistivity ‘ρ’, mobility ‘μ’, and dielectric constant ‘e’ as a function of temperature was also investigated and was seen to depend on rare earth concentration in the ferrite structure.

Effect of non-magnetic rare earth substitution for A site in mixed anion APX superconductors

We report the improvement of superconducting transition temperature (T c) by nonmagnetic rare earth atom substitution for A site in APX-based Zr(P, S)2, Hf(P, Se)2 and Hf(P, S)2 superconductors. The partial non-magnetic rare earth Lu atom substitution at Zr site of ZrPS, as opposed to the case of Zr(P, Se)2, shows that lattice constants a and c decrease monotonically with increasing nominal substitution y. It is shown that the maximum T c for ZrPS was increased from 3.70 K to 6.36 K. In HfP1.55Se0.45, when Hf site is partially substituted with Lu atoms (or Y atoms), lattice constant a shrinks and c expands monotonically with increasing nominal rare earth substitution y. T c was also increased from 4.88 K to 5.89 K. In HfP1.45S0.55, when Hf site is partially substituted with Lu atoms (or Y atoms), lattice constant a shrinks slightly and c expands monotonically with increasing y. T c was also increased from 3.16 K to 5.86 K. In this paper, the doping behaviour by partial substitution and the increase of T c is discussed.

NADİR TOPRAK KATKISININ SPİNEL FERRİTLERİN MANYETİK ÖZELLİKLERİNE ETKİSİ

Nano-size ferrites (NSF) are magnetic nanoparticles (MNPs) which have attracted great interest in the last decades owing to their high surface area-to-volume ratio, high saturation magnetization, initial permeability, etc. Nickel-copper-zinc ferrites are especially used in multi-layer chip inductors (MLCIs) which are found in mobile phones, camcorders, notebook computers, etc. MLCIs are composed of alternating layers of silver electrodes and soft ferrites. Thus, it is important to develop magnetic characteristics in ferrites for requiring less ferrite layers and hence to obtain further miniaturized devices. The goal of our study is to investigate the effect of rare earth substitution of Ni-Cu-Zn ferrite nanoparticles. Ni-Cu-Zn NSFs substituted with rare earth metal (RE) ions Eu3+, Tb3+, and Dy3+ in varying concentrations were obtained by a sonochemical method. We investigated the crystal structure, chemical bonding, morphology and magnetic characteristics of the Ni-Cu-Zn NSFs by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM), respectively. The phase purity of the samples was confirmed by the XRD analysis. Stretching vibrations of spinel ferrites were verified by the FT-IR analysis. VSM results reveal that the rare earth substitution has a significant effect on the magnetic properties of the Ni-Cu-Zn NSFs.

Structural stabilization of δ-phase Bi2O3 in the MgBi1.5RE0.5O4 system through rare earth substitution for improved ionic conductivity

Fluorite-structured Bi2O3 oxide materials are promising candidates for oxygen ion conductors. In this regard, we attempted to stabilise the δ-phase through rare earth ion substitution in a new series of compositions: MgBi1.5RE0.5O4 (RE = Nd, Sm, Gd, Dy, Y). They exhibit a phase transformation from a rhombohedral (Nd-Gd) to a fluorite-type (Dy, Y) structure as the ionic radius of rare earth decreases. The electrical property studies show that conductivity is a function of crystalline structure and lattice volume. Maximum conductivity of 4.3 × 10−2 S/cm is obtained for the Y composition at 1023 K. The conductivity of the rhombohedral composition decreases as the lattice volume decreases associated with the increased activation energy. Contrastingly, the conductivity decreases with the increase of the lattice volume from Y to Dy on account of δ-phase instability at higher temperature. These results demonstrate that structural stabilization of δ-phase Bi2O3 can be achieved through Y substitution with more thermal stability.

Coercivity enhancement mechanism of grain boundary diffused Nd-Fe-B sintered magnets by magnetic domain evolution observation

The grain boundary diffusion (GBD) technology was used to prepare high performance Nd-Fe-B sintered magnets by NdH3 and TbH3 nanoparticle diffusion. The factors affecting the coercivity of GBD magnets include distribution of rare earth rich grain boundary phase and substitution of the heavy rare earth. In order to distinguish the influence of various factors on the coercivity, the microstructure and magnetic domain evolution of the original, reference, Nd-diffused, and Tb-diffused magnets were analyzed. The core-shell structure formed by heavy rare earth substitution is the main factor of coercivity enhancement, and it can transform the magnetic domain reversal mode from easy-nucleation (EN) to difficult-nucleation (DN). With increasing the diffusion depth, the shell of the core-shell structure gradually becomes thinner, DN grains gradually decrease while the EN grains gradually increase, indicating that the magnetic domain reversal mode is directly related to the core-shell structure.

Thermodynamic and corrosion study of Sm1-xMgxNiy (y = 3.5 or 3.8) compounds forming reversible hydrides

AB5 compounds (A = rare earth, B = transition metal) have been widely studied as anodes for Ni-MH applications. However, they have reached their technical limitations and the search for new promising materials with high capacity is foreseen. ABy compounds (2 < y < 5) are good candidates. They are made by stacking [AB5] and [A2B4] units along the c crystallographic axis. The latter unit allows a large increase in capacity, while the [AB5] unit provides good cycling stability. Consequently, the AB3.8 composition (i.e. A5B19 with three [AB5] for one [A2B4]) is expected to exhibit better cycling stability than the AB3.5 (i.e. A2B7 with two [AB5] for one [A2B4]). Furthermore, substitution of rare earth by light magnesium improves both the capacity and cycling stability. In this paper, we compare the hydrogenation and corrosion properties of two binary compounds, SmNi3.5 and SmNi3.8, and two pseudo-binary ones, (Sm, Mg)Ni3.5 and (Sm, Mg)Ni3.8. A better solid-gas cycling stability is highlighted for the binary SmNi3.8. The pseudo-binary compounds also exhibit higher cycling stability than the binary ones. Furthermore, their resistance to corrosion was investigated.

Impact of A-site rare earth substitution on structural, magnetic, optical and transport properties of double perovskites

In the current research work R2CoMnO6 (R = La, Sm, Gd and Dy) double perovskites (DPOs) have been synthesized using auto combustion sol-gel method. Structural characterizations were carried out by X-ray diffraction technique and the analysis confirms the correct crystal structure by Rietveld refinement with a monoclinic symmetry (space group P21/n) in all DPOs. Crystallite size has been calculated by using Scherrer and Williamson-Hall (W-H) methods and found that the crystallite size with the decrease in ionic radius (RLn) decreases from 61.37–49.03 nm on average. The IR reflectivity spectrums fitted by the Lorentz oscillator model reveal that the given DPOs have a monoclinic structure and change of R-site also has ability to impact on the crystal structure. The optical band gap has been estimated in the range of 1.30–1.60 eV reflecting that the considered DPOs have potential to be used as light harvesting materials. The resistivity data of all DPOs depict semiconductor like behavior above room temperature and this behavior has been best described by small polaron hopping (SPH) conduction mechanism. Dielectric measurements exhibit usual dielectric dispersion, which is due to the Maxwell-Wagner-type interfacial polarization in all DPOs. AC conductivity measurement also suggests the conduction is due to SPH.

Enhancement of temperature coefficient of resistance (TCR) and magnetoresistance (MR) of La0.67–xRExCa0.33MnO3 (x = 0, 0.1; RE = Gd, Nd, Sm) system via rare-earth substitution

We investigated the influence of 10% substitution of rare-earth (RE) elements on the crystallographic, transport, and magnetic properties of La0.67–xRExCa0.33MnO3(RE = Nd, Sm, and Gd, x = 0.0, 0.1) manganite perovskite compounds. The bulk polycrystalline samples were synthesized using solid-state reaction method. The phase purity and crystal structure of studied samples were confirmed by room temperature X-ray diffraction followed by the Rietveld refinement analysis. A high temperature insulator to low temperature metal phase transition is observed in electrical transport measurement. We observed an enhancement in the temperature coefficient of resistance (TCR) and magnetoresistance (MR) by partially substituting La with RE ions. The maximum TCR ≈ 22% and MR ≈ 96% are observed in Gd doped sample. The magnetic transition temperature, Tc, decreases from ∼254 K for the pristine sample to about ∼165 K for the Gd-doped sample. Our analysis of electrical and thermal transport data shows that the Small Polaron Hopping (SPH) is predominant at high temperatures conduction mechanism, whereas at low temperatures mechanism is dominated by electron-magnon scattering. The high temperature insulator paramagnetic phase to low temperature metallic ferromagnetic phase transitions are also observed in thermal conductivity and specific heat.

Interfacial Dzyaloshinskii-Moriya interaction arising from rare-earth orbital magnetism in insulating magnetic oxides

The Dzyaloshinskii-Moriya interaction (DMI) is responsible for exotic chiral and topological magnetic states such as spin spirals and skyrmions. DMI manifests at metallic ferromagnet/heavy-metal interfaces, owing to inversion symmetry breaking and spin-orbit coupling by a heavy metal such as Pt. Moreover, in centrosymmetric magnetic oxides interfaced by Pt, DMI-driven topological spin textures and fast current-driven dynamics have been reported, though the origin of this DMI is unclear. While in metallic systems, spin-orbit coupling arises from a proximate heavy metal, we show that in perpendicularly-magnetized iron garnets, rare-earth orbital magnetism gives rise to an intrinsic spin-orbit coupling generating interfacial DMI at mirror symmetry-breaking interfaces. We show that rare-earth ion substitution and strain engineering can significantly alter the DMI. These results provide critical insights into the origins of chiral magnetism in low-damping magnetic oxides and identify paths toward engineering chiral and topological states in centrosymmetric oxides through rare-earth ion substitution.