We report the observation of extraordinarily robust zero-resistance superconductivity in the pressurized (TaNb)0.67(HfZrTi)0.33 high-entropy alloy––a material with a body-centered-cubic crystal structure made from five randomly distributed transition-metal elements. The transition to superconductivity (TC) increases from an initial temperature of 7.7 K at ambient pressure to 10 K at ∼60 GPa, and then slowly decreases to 9 K by 190.6 GPa, a pressure that falls within that of the outer core of the earth. We infer that the continuous existence of the zero-resistance superconductivity from 1 atm up to such a high pressure requires a special combination of electronic and mechanical characteristics. This high-entropy alloy superconductor thus may have a bright future for applications under extreme conditions, and also poses a challenge for understanding the underlying quantum physics.

•NaxCoO2 materials (x = 0.75, 0.65, 0.52, 0.36) were synthesized through a sol-gel method and subsequent chemical deintercalation.•NaxCoO2 materials demonstrate an increasing catalytic OER activity as the Na level decreases.•XPS detected an increasing amount of Co(III) on materials surface from Na0.75CoO2 to Na0.36CoO2.•A chemistry model based on oxygen vacancies was proposed to explain the observed phenomena.We present a study based on the layered oxide system NaxCoO2 as an oxygen evolution reaction (OER) catalyst, where the formal oxidation state of Co can be continuously increased, above 3+, through Na-ion deintercalation. Accompanying this increase of formal Co oxidation state, the overpotential for the catalytic oxygen evolution reaction (OER) at 10 mA/cm2 decreases from 470 mV to 415 mV, while all the NaxCoO2 materials (x = 0.75, 0.65, 0.52, 0.36) share a common Tafel slope of 41(±5) mV/decade, implying a common rate-limiting process for the whole series. Our use of X-ray photoelectron spectroscopy (XPS) on the de-intercalation-derived NaxCoO2 catalysts, on the other hand, led to the unexpected observation that the percentage of surface Co(III) increases from 23% to 37% even as the Na deintercalation increases the formal Co oxidation state above 3+. These observations suggest that when the formal oxidation state of the central metal is pushed to an unusually high value, i.e. Co(IV) in this case, oxygen vacancies on the materials surface formed from the relaxation of the highly oxidized metal to a more stable oxidation state are the key to improving catalytic OER activity.Download high-res image (164KB)Download full-size image

The optimal functionalities of materials often appear at phase transitions involving simultaneous changes in the electronic structure and the symmetry of the underlying lattice. It is experimentally challenging to disentangle which of the two effects––electronic or structural––is the driving force for the phase transition and to use the mechanism to control material properties. Here we report the concurrent pumping and probing of Cu2S nanoplates using an electron beam to directly manipulate the transition between two phases with distinctly different crystal symmetries and charge-carrier concentrations, and show that the transition is the result of charge generation for one phase and charge depletion for the other. We demonstrate that this manipulation is fully reversible and nonthermal in nature. Our observations reveal a phase-transition pathway in materials, where electron-induced changes in the electronic structure can lead to a macroscopic reconstruction of the crystal structure.

We report the synthesis and crystal structures of compounds of the type RE3Sb3Zn2O14 (La3Sb3Zn2O14, Pr3Sb3Zn2O14, Nd3Sb3Zn2O14, Sm3Sb3Zn2O14, Eu3Sb3Zn2O14, and Gd3Sb3Zn2O14), a series of novel rhombohedral pyrochlore derivatives with rare earth ions on a two-dimensional Kagome lattice. Synchrotron powder X-ray diffraction was used to solve the structures of the compounds. The rare earth ions are fully atomically ordered in a symmetric magnetic Kagome lattice. The nonmagnetic lattice contains one ion (Zn) that is displaced from the center of its coordination polyhedron in a random fashion. The structure differs from the common cubic A2B2O7 pyrochlore type because it forms a layered rather than three-dimensional structure through ordering of ZnRE3 in the A sites and ZnSb3 in the B sites. Magnetic property measurements indicate the compounds display dominantly antiferromagnetic interactions between spins, and no signs of magnetic ordering above 1.8 K except possibly the Pr and Eu cases. RE3Sb3Zn2O14 is the first series of this structure type in which the rare earth is the only magnetic ion in the structure. This family is therefore an archetype for exploring rare earth magnetism on a two-dimensional Kagome lattice.

We report the crystal structures and elementary properties of the new aurobismuthides La3Au3Bi4, Ce3Au3Bi4, Pr3Au3Bi4, Nd3Au3Bi4, Sm3Au3Bi4, and Gd3Au3Bi4. These ternary compounds are found only for the large lanthanides and crystallize in the cubic Y3Au3Sb4 structure type, which is a stuffed Th3P4-type derivative. The compounds are electron-precise, leading to semiconducting behavior, and display magnetic properties arising from localized lanthanide f states. Resistivity data, Seebeck coefficient measurements, and electronic structure calculations suggest that these phases are heavily doped, p-type semiconductors. Nd3Au3Bi4 and Sm3Au3Bi4 have Seebeck coefficients of 105 and 190 μV/K at 350 K, respectively, making them worthy of further thermoelectric studies.

We consider a system where structural polymorphism suggests the possible existence of superconductivity through the implied structural instability. SrPd2Bi2 has two polymorphs, which can be controlled by the synthesis temperature: a tetragonal form (CaBe2Ge2-type) and a monoclinic form (BaAu2Sb2-type). Although the crystallographic difference between the two forms may, at first, seem trivial, we show that tetragonal SrPd2Bi2 is superconducting at 2.0 K, whereas monoclinic SrPd2Bi2 is not. We rationalize this finding and place it in context with other 1–2–2 phases.

The recent discovery of extreme magnetoresistance (XMR) in LaSb introduced lanthanum monopnictides as a new platform to study this effect in the absence of broken inversion symmetry or protected linear band crossing. In this work, we report XMR in LaBi. Through a comparative study of magnetotransport effects in LaBi and LaSb, we construct a temperature−field phase diagram with triangular shape that illustrates how a magnetic field tunes the electronic behavior in these materials. We show that the triangular phase diagram can be generalized to other topological semimetals with different crystal structures and different chemical compositions. By comparing our experimental results to band structure calculations, we suggest that XMR in LaBi and LaSb originates from a combination of compensated electron−hole pockets and a particular orbital texture on the electron pocket. Such orbital texture is likely to be a generic feature of various topological semimetals, giving rise to their small residual resistivity at zero field and subject to strong scattering induced by a magnetic field.

High-entropy alloys are made from random mixtures of principal elements on simple lattices, stabilized by a high mixing entropy. The recently discovered body-centered cubic (BCC) Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor appears to display properties of both simple crystalline intermetallics and amorphous materials; e.g., it has a well-defined superconducting transition along with an exceptional robustness against disorder. Here we show that the valence electron count dependence of the superconducting transition temperature in the high-entropy alloy falls between those of analogous simple solid solutions and amorphous materials and test the effect of alloy complexity on the superconductivity. We propose high-entropy alloys as excellent intermediate systems for studying superconductivity as it evolves between crystalline and amorphous materials.

We report the magnetic characterization of the Cr-doped layered dichalcogenide TiSe2. The temperature dependent magnetic susceptibilities are typical of those seen in geometrically frustrated insulating antiferromagnets. The Cr moment is close to the spin-only value, and the Curie–Weiss temperatures (θcw) are between −90 and −230 K. Freezing of the spin system, which is glassy, characterized by peaks in the ac and dc susceptibility and specific heat, does not occur until below T/θcw = 0.05. The CDW transition seen in the resistivity for pure TiSe2 is still present for 3% Cr substitution but is absent by 10% substitution, above which the materials are metallic and p-type. Structural refinements, magnetic characterization, and chemical considerations indicate that the materials are of the type Ti1–xCrxSe2-x/2 for 0 ≤ x ≤ 0.6.

We report that at low Ru contents, up to x = 0.2, the Zr5Sb3−xRux solid solution forms in the hexagonal Mn5Si3 structure type of the host (x = 0), but that at higher Ru contents (x = 0.4–0.6) the solid solution transforms into the tetragonal W5Si3 structure type. We find that tetragonal Zr5Sb2.4Ru0.6 is superconducting at 5 K, significantly higher than the transition temperature of hexagonal Zr5Sb3 (x = 0), which has a Tc of 2.3 K. In support of a hypothesis that certain structure types are favorable for superconductivity, we describe how the W5Si3 and Tl5Te3 structure types, both of which support superconductivity, are derived from the parent Al2Cu type structure, in which superconductors are also found. Electronic structure calculations show that in Zr10Sb5Ru, a model for the new superconducting compound, the Fermi level is located on a peak in the electronic density of states.

We present transition metal-embedded (T@Gan) endohedral Ga-clusters as a favorable structural motif for superconductivity and develop empirical, molecule-based, electron counting rules that govern the hierarchical architectures that the clusters assume in binary phases. Among the binary T@Gan endohedral cluster systems, Mo8Ga41, Mo6Ga31, Rh2Ga9, and Ir2Ga9 are all previously known superconductors. The well-known exotic superconductor PuCoGa5 and related phases are also members of this endohedral gallide cluster family. We show that electron-deficient compounds like Mo8Ga41 prefer architectures with vertex-sharing gallium clusters, whereas electron-rich compounds, like PdGa5, prefer edge-sharing cluster architectures. The superconducting transition temperatures are highest for the electron-poor, corner-sharing architectures. Based on this analysis, the previously unknown endohedral cluster compound ReGa5 is postulated to exist at an intermediate electron count and a mix of corner sharing and edge sharing cluster architectures. The empirical prediction is shown to be correct and leads to the discovery of superconductivity in ReGa5. The Fermi levels for endohedral gallide cluster compounds are located in deep pseudogaps in the electronic densities of states, an important factor in determining their chemical stability, while at the same time limiting their superconducting transition temperatures.

Polymorphism in materials often leads to significantly different physical properties—the rutile and anatase polymorphs of TiO2 are a prime example. Polytypism is a special type of polymorphism, occurring in layered materials when the geometry of a repeating structural layer is maintained but the layer-stacking sequence of the overall crystal structure can be varied; SiC is an example of a material with many polytypes. Although polymorphs can have radically different physical properties, it is much rarer for polytypism to impact physical properties in a dramatic fashion. Here we study the effects of polytypism and polymorphism on the superconductivity of TaSe2, one of the archetypal members of the large family of layered dichalcogenides. We show that it is possible to access two stable polytypes and two stable polymorphs in the TaSe2−xTex solid solution and find that the 3R polytype shows a superconducting transition temperature that is between 6 and 17 times higher than that of the much more commonly found 2H polytype. The reason for this dramatic change is not apparent, but we propose that it arises either from a remarkable dependence of Tc on subtle differences in the characteristics of the single layers present or from a surprising effect of the layer-stacking sequence on electronic properties that are typically expected to be dominated by the properties of a single layer in materials of this kind.

We report a new family of ternary 111 hexagonal LnAuSb (Ln = La–Nd, Sm) compounds that, with a 19 valence electron count, has one extra electron compared to all other known LnAuZ compounds. LaAuSb, CeAuSb, PrAuSb, NdAuSb, and SmAuSb crystallize in the YPtAs-type structure, and have a doubled unit cell compared to other LnAuZ phases as a result of the buckling of the Au–Sb honeycomb layers to create interlayer Au–Au dimers. The dimers accommodate the one excess electron per Au and thus these new phases can be considered Ln23+(Au–Au)0Sb23–. Band structure, density of states, and crystal orbital calculations confirm this picture, which results in a nearly complete band gap between full and empty electronic states and stable compounds; we can thus present a structural stability phase diagram for the LnAuZ (Z = Ge, As, Sn, Sb, Pb, Bi) family of phases. Those calculations also show that LaAuSb has a bulk Dirac cone below the Fermi level. The YPtAs-type LnAuSb family reported here is an example of the uniqueness of gold chemistry applied to a rigidly closed shell system in an unconventional way.

We present the structure and magnetic properties of the honeycomb anhydrate NaNi2BiO6-δ and its monolayer hydrate NaNi2BiO6-δ·1.7H2O, synthesized by deintercalation of the layered α-NaFeO2-type honeycomb compound Na3Ni2BiO6. The anhydrate adopts ABAB-type oxygen packing and a one-layer hexagonal unit cell, whereas the hydrate adopts an oxygen packing sequence based on a three-layer rhombohedral subcell. The metal-oxide layer separations are 5.7 Å in the anhydrate and 7.1 Å in the hydrate, making the hydrate a quasi 2-D honeycomb system. The compounds were characterized through single crystal diffraction, powder X-ray diffraction, thermogravimetric analysis, and elemental analysis. Temperature-dependent magnetic susceptibility measurements show both to have negative Weiss temperatures (−18.5 and −14.6 K, respectively) and similar magnetic moments (2.21 and 2.26 μB/Ni, respectively), though the field-dependent magnetization and heat capacity data suggest subtle differences in their magnetic behavior. The magnetic moments per Ni are relatively high, which we suggest is due to the presence of a mixture of Ni2+ and Ni3+ caused by oxygen vacancies.

Topological surface states, a new kind of electronic state of matter, have recently been observed on the cleaved surfaces of crystals of a handful of small band gap semiconductors. The underlying chemical factors that enable these states are crystal symmetry, the presence of strong spin–orbit coupling, and an inversion of the energies of the bulk electronic states that normally contribute to the valence and conduction bands. The goals of this review are to briefly introduce the physics of topological insulators to a chemical audience and to describe the chemistry, defect chemistry, and crystal structures of the compounds in this emergent field.

Seebeck coefficients, electrical resistivities, thermal conductivities and figure of merit ZT of Bi2−xSbxTeSe2 crystals (x=0.8, 0.9, 1.0, 1.1, and 1.2) measured along the hexagonal basal plane are presented. The crystals gradually change from n- to p-type with increasing Sb content, with the crossover lying in the region between x=1.0 and 1.1. The crossover is accounted for by a simple (p–n) electron-hole compensation model, as supported by carrier concentrations determined from Hall measurements. ZT was found to be maximized near the crossover on the p-type side, with the high electrical resistance of the Se-rich crystals apparently the limiting factor in the performance. These materials may serve as a basis for future nanostructuring or doping studies.Highlights► We report thermoelectric properties of Bi2−xSbxTeSe2 (x=0.8, 0.9, 1.0, 1.1, and 1.2). ► Higher Sb content leads to a change from n- to p-type between x=1.0 and 1.1. ► Thermoelectric efficiency ZT is maximized near the n–p crossover (x=1.1).

The preparation of PbSe2 through the reaction of PbSe with excess Se at 4.5 GPa and 650 °C is reported. The crystal structure, determined from X-ray powder diffraction data (CuAl2 structure type, I4/mcm (#140), a = 6.42695(11) Å, c = 7.70254(13) Å, Z = 4), consists of layers of [Se2]2- dimers with Pb2+ in square antiprismatic coordination with Se. This is a rare crystal structure for divalent metal chalcogenides, previously only identified for SrS2 and BaTe2. Undoped PbSe2 as well as Bi3+- and Ag+-doped samples (10% Pb substitution) show semi-metallic resistivity down to 0.4 K. Magnetic susceptibility measurement of PbSe2 shows no magnetic ordering above 1.8 K. The Seebeck coefficients show nearly linear behavior from 35 to 400 K and the largest numerical values are found in the case of undoped PbSe2, + 99 μVK−1, and Bi3+-doped PbSe2, - 146 μVK−1, at the highest temperature measured, 400 K.

It has been argued that the very high transition temperatures of the highest Tc cuprate superconductors are facilitated by enhanced CuO2 plane coupling through heavy metal oxide intermediary layers. Whether enhanced coupling through intermediary layers can also influence Tc in the new high Tc iron arsenide superconductors has never been tested due the lack of appropriate systems for study. Here we report the crystal structures and properties of two iron arsenide superconductors, Ca10(Pt3As8)(Fe2As2)5 (the “10-3-8 phase”) and Ca10(Pt4As8)(Fe2As2)5 (the “10-4-8 phase”). Based on -Ca-(PtnAs8)-Ca-Fe2As2- layer stacking, these are very similar compounds for which the most important differences lie in the structural and electronic characteristics of the intermediary platinum arsenide layers. Electron doping through partial substitution of Pt for Fe in the FeAs layers leads to Tc of 11 K in the 10-3-8 phase and 26 K in the 10-4-8 phase. The often-cited empirical rule in the arsenide superconductor literature relating Tc to As-Fe-As bond angles does not explain the observed differences in Tc of the two phases; rather, comparison suggests the presence of stronger FeAs interlayer coupling in the 10-4-8 phase arising from the two-channel interlayer interactions and the metallic nature of its intermediary Pt4As8 layer. The interlayer coupling is thus revealed as important in enhancing Tc in the iron pnictide superconductors.

Magnetic ground states in solids often arise as a result of a delicate balance between competing factors. One currently active area of research in magnetic materials involves compounds in which long-range magnetic ordering at low temperatures is frustrated by the geometry of the crystalline lattice, a situation known as geometrical magnetic frustration. The number of systems known to display the effects of such frustration is growing, but those that are sufficiently simple from theoretical, chemical, and physical perspectives to allow for detailed understanding remain very few. A search for model compounds in this family has led us to the double perovskites Ba2LnSbO6 and Sr2LnSbO6 (Ln = Dy, Ho, and Gd) reported here. Ba2DySbO6,Ba2HoSbO6,Sr2DySbO6, and Sr2HoSbO6 are structurally characterized by powder neutron diffraction at ambient temperature. The trivalent lanthanides and pentavalent antimony are found to be fully ordered in the double-perovskite arrangement of alternating octahedra sharing corner oxygens. In such a structure, the lanthanide sublattice displays a classical fcc arrangement, an edge-shared network of tetrahedra known to result in geometric magnetic frustration. No magnetic ordering is observed in any of these compounds down to temperatures of 2 K, and in the case of the Dy-based compounds in particular, frustration of the magnetic ordering is clearly present. Lanthanide-based double perovskites are proposed to be excellent model systems for the detailed study of geometric magnetic frustration.

A long-established area of scientific excellence in Europe, solid state chemistry has emerged in the US in the past two decades as a field experiencing rapid growth and development. At its core, it is an interdisciplinary melding of chemistry, physics, engineering, and materials science, as it focuses on the design, synthesis and structural characterization of new chemical compounds and characterization of their physical properties. As a consequence of this inherently interdisciplinary character, the solid state chemistry community is highly open to the influx of new ideas and directions. The inclusionary character of the field’s culture has been a significant factor in its continuing growth and vitality.This report presents an elaboration of discussions held during an NSF-sponsored workshop on Future Directions in Solid State Chemistry, held on the UC Davis Campus in October 2001. That workshop was the second of a series of workshops planned in this topical area. The first, held at NSF headquarters in Arlington, Virginia, in January of 1998, was designed to address the core of the field, describing how it has developed in the US and worldwide in the past decade, and how the members of the community saw the central thrusts of research and education in solid state chemistry proceeding in the next several years. A report was published on that workshop (J.M. Honig, chair, “Proceedings of the Workshop on the Present Status and Future Developments of Solid State Chemistry and Materials”, Arlington, VA, January 15–16, 1998) describing the state of the field and recommendations for future development of the core discipline.In the spirit of continuing to expand the scope of the solid state chemistry community into new areas of scientific inquiry, the workshop elaborated in this document was designed to address the interfaces between our field and fields where we thought there would be significant opportunity for the development of new scientific advancements through increased interaction. The 7 topic areas, described in detail in this report, ranged from those with established ties to solid state chemistry such as Earth and planetary sciences, and energy storage and conversion, to those such as condensed matter physics, where the connections are in their infancy, to biology, where the opportunities for connections are largely unexplored. Exciting ties to materials chemistry were explored in discussions on molecular materials and nanoscale science, and a session on the importance of improving the ties between solid state chemists and experts in characterization at national experimental facilities was included. The full report elaborates these ideas extensively.

The experimental relation between the superconducting transition temperature (Tc) and lattice size for the lanthanide nickel borocarbides is clarified. The electronic density of states (DOS) at the Fermi energy is calculated by the LMTO method for selected non-magnetic lanthanides. The Tc and the DOS are both shown to scale in the same way with a structural parameter that characterizes the bond angle in the NiB4 tetrahedra. The results strongly support arguments that the suppression of superconductivity on going from smaller to larger lanthanides in the quaternary nickel borocarbides is structurally driven. A structure–Tc relationship of this type is unusual for intermetallic superconductors.

The basic magnetic and electronic properties of most binary compounds have been well known for decades. The recent discovery1 of superconductivity at 39 K in the simple binary ceramic compound magnesium diboride, MgB2, was therefore surprising. Indeed, this material has been known and structurally characterized since the mid 1950s (ref. 2), and is readily available from chemical suppliers (it is commonly used as a starting material for chemical metathesis reactions3). Here we show that the addition of electrons to MgB2, through partial substitution of Al for Mg, results in the loss of superconductivity. Associated with the Al substitution is a subtle but distinct structural transition, reflected in the partial collapse of the spacing between boron layers near an Al content of 10 per cent. This indicates that superconducting MgB2 is poised very near a structural instability at slightly higher electron concentrations.

Understanding the complexities of electronic and magnetic ground states in solids is one of the main goals of solid-state physics. Transition-metal oxides have proved to be particularly fruitful in this regard, especially for those materials with the perovskite structure, where the special characteristics of transition-metal–oxygen orbital hybridization determine their properties. Ruthenates have recently emerged as an important family of perovskites because of the unexpected evolution from high-temperature ferromagnetism in SrRuO3 to low-temperature superconductivity in Sr2RuO4 (refs 1, 2). Here we show that a ruthenate in a different structural family, La4Ru6O19, displays a number of highly unusual properties, most notably non-Fermi-liquid behaviour. The properties of La4Ru6O19 have no analogy among the thousands of previously characterized transition-metal oxides. Instead, they resemble those of CeCu6-xAux—a widely studied f-electron-based heavy fermion intermetallic compound that is often considered as providing the best example of non-Fermi-liquid behaviour. In the ruthenate, non-Fermi-liquid behaviour appears to arise from just the right balance between the interactions of localized electronic states derived from Ru–Ru bonding and delocalized states derived from Ru–O hybridization.

The interplay of magnetic interactions, the dimensionality of the crystal structure and electronic correlations in producing superconductivity is one of the dominant themes in the study of the electronic properties of complex materials. Although magnetic interactions and two-dimensional structures were long thought to be detrimental to the formation of a superconducting state, they are actually common features of both the high transition-temperature (Tc) copper oxides and low-Tc material Sr2RuO4, where they appear to be essential contributors to the exotic electronic states of these materials1. Here we report that the perovskite-structured compound MgCNi3 is superconducting with a critical temperature of 8 K. This material is the three-dimensional analogue of the LnNi2B2C family of superconductors, which have critical temperatures up to 16 K (ref. 2). The itinerant electrons in both families of materials arise from the partial filling of the nickel d-states, which generally leads to ferromagnetism as is the case in metallic Ni. The high relative proportion of Ni in MgCNi3 suggests that magnetic interactions are important, and the lower Tc of this three-dimensional compound—when compared to the LnNi2B2C family—contrasts with conventional ideas regarding the origins of superconductivity.

Topological surface states, a new kind of electronic state of matter, have recently been observed on the cleaved surfaces of crystals of a handful of small band gap semiconductors. The underlying chemical factors that enable these states are crystal symmetry, the presence of strong spin–orbit coupling, and an inversion of the energies of the bulk electronic states that normally contribute to the valence and conduction bands. The goals of this review are to briefly introduce the physics of topological insulators to a chemical audience and to describe the chemistry, defect chemistry, and crystal structures of the compounds in this emergent field.

We report that at low Ru contents, up to x = 0.2, the Zr5Sb3−xRux solid solution forms in the hexagonal Mn5Si3 structure type of the host (x = 0), but that at higher Ru contents (x = 0.4–0.6) the solid solution transforms into the tetragonal W5Si3 structure type. We find that tetragonal Zr5Sb2.4Ru0.6 is superconducting at 5 K, significantly higher than the transition temperature of hexagonal Zr5Sb3 (x = 0), which has a Tc of 2.3 K. In support of a hypothesis that certain structure types are favorable for superconductivity, we describe how the W5Si3 and Tl5Te3 structure types, both of which support superconductivity, are derived from the parent Al2Cu type structure, in which superconductors are also found. Electronic structure calculations show that in Zr10Sb5Ru, a model for the new superconducting compound, the Fermi level is located on a peak in the electronic density of states.

We report the synthesis and crystal structures of compounds of the type RE3Sb3Zn2O14 (La3Sb3Zn2O14, Pr3Sb3Zn2O14, Nd3Sb3Zn2O14, Sm3Sb3Zn2O14, Eu3Sb3Zn2O14, and Gd3Sb3Zn2O14), a series of novel rhombohedral pyrochlore derivatives with rare earth ions on a two-dimensional Kagome lattice. Synchrotron powder X-ray diffraction was used to solve the structures of the compounds. The rare earth ions are fully atomically ordered in a symmetric magnetic Kagome lattice. The nonmagnetic lattice contains one ion (Zn) that is displaced from the center of its coordination polyhedron in a random fashion. The structure differs from the common cubic A2B2O7 pyrochlore type because it forms a layered rather than three-dimensional structure through ordering of ZnRE3 in the A sites and ZnSb3 in the B sites. Magnetic property measurements indicate the compounds display dominantly antiferromagnetic interactions between spins, and no signs of magnetic ordering above 1.8 K except possibly the Pr and Eu cases. RE3Sb3Zn2O14 is the first series of this structure type in which the rare earth is the only magnetic ion in the structure. This family is therefore an archetype for exploring rare earth magnetism on a two-dimensional Kagome lattice.