Search

Yb14MnSb11 is a member of a remarkable structural family of compounds that are classified according to the concept of Zintl. This structure type, of which the prototype is Ca14AlSb11, provides a flexible framework for tuning structure-property relationships and hence the physical and chemical properties of compounds. Compounds within this family show exceptional high temperature thermoelectric performance at temperatures above 300 K and unique magnetic and transport behavior at temperatures below 300 K. This review provides an overview of the structure variants, the magnetic properties, and the thermoelectric properties. Suggestions for directions of future research are provided.

Within the field of thermoelectric materials for energy conversion magnesium silicide, Mg2Si, is an outstanding candidate due to its low density, abundant constituents and low toxicity. However electronic and thermal tuning of the material is a required necessity to improve its Figure of Merit, zT. Doping of Yb via reactive YbH2 into the structure is performed with the goal of reducing the thermal conductivity. Hydrogen is released as a by-product at high temperatures allowing for facile incorporation of Yb into the structure. We report on the properties of Yb- and Bi-doped Mg2Si prepared with MgH2 and YbH2 with the focus on the synthetic conditions, and samples’ microstructure, investigated by various electron microscopy techniques. Yb is found in the form of both Yb3Si5 inclusions and Yb dopant segregated at the grain boundary substituting for Mg. The addition of 1 at% Yb concentration reduced the thermal conductivity, providing a value of 30 mW/cm K at 800 K. In order to adjust carrier concentration, the sample is additionally doped with Bi. The impact of the microstructure on the transport properties of the obtained material is studied. Idealy, the reduction of the thermal conductivity is achieved by doping with Yb and the electronic transport is adjusted by doping with Bi. Large grain microstructure facilitates the electronic transport. However, the synthetic conditions that provide the optimized microstructure for electrical transport do not facilitate the additional Yb dopant incorporation. Therefore, the Yb and Bi containing sample with the optimized microstructure provides a zT=0.46 at 800 K.

Yb14MnSb11 is the most efficient bulk p-type thermoelectric material for high temperature applications. Materials with Y and Sc substitutions in Yb14MnSb11 were made both in Sn-flux and by ball milling. These small 3+ rare earth (RE) cations were introduced with the goal of providing chemical pressure on the structure. The RE3+ cation is smaller than Yb2+ and also donates one additional electron to this p-type semiconductor. In Yb14−xRExMnSb11 (RE = Sc, Y) the maximum x was about 0.5. X-ray diffraction experiments on the single crystals obtained from Sn-flux showed that Sc preferentially substitutes for Yb(1) and Yb(3), and decreases the size of the unit cell by about 0.3%. Y substitutes on all Yb sites and increases the size of the unit cell by about 0.2%. Samples with Yb14−xRExMnSb11 (x~0.3) were prepared via powder metallurgy and spark plasma sintering for transport and thermal conductivity measurements. Electron microprobe of the Sc-substituted sample showed small regions (≤1 μ m) containing greater amounts of Sc, and X-ray powder diffraction of the ball milled Sc sample could be fitted as phase pure Yb14−xScxMnSb11. Y-substituted samples showed larger regions of excess Y in electron microprobe, and small amounts of Yb4Sb3 in X-ray powder diffraction. The Sc sample has slightly reduced carrier concentration over optimized Yb14MnSb11, while the Y samples have even lower carrier concentrations. These carrier concentrations lead to comparable resistivity to Yb14MnSb11 in the Sc-substituted material, and higher resistivities in the Y-substituted material. All materials had similar Seebeck coefficients that slightly exceed Yb14MnSb11 at high temperatures, with the Sc-substituted sample having the highest despite having a higher carrier concentration. Sc-substituted samples also had a slightly higher thermal conductivity over the Y-substituted samples, which had comparable thermal conductivity to Yb14MnSb11. The zT values of the Sc and Y substituted samples are similar (zT1000 K~0.8), however below that of Yb14MnSb11 due to the compensation of Seebeck and resistivity.

Single crystals of Yb14−xRExMnSb11 (x~0.1, 0.4; RE = Tb, Dy, Ho) have been prepared as a solid solution by Sn flux reactions of the elements. They crystallize in the Ca14AlSb11 structure type in the I41/acd space group. The RE3+preferentially substitutes on the Yb(1) site which is the smallest volume Yb containing polyhedron. In the case of Ho3+, a small amount of Ho3+ also substitutes on the Yb(4) site. The ferromagnetic ordering temperature of Yb14MnSb11 is reduced from 53 K to 41 K as x increases and dependent on the identity of the RE. This is attributed to the reduction in carriers and reduced screening of the Mn2+ local moment. The effective moments, μeff, agree well with the calculated moments assuming the RE substitutes as a trivalent cation. The largest coercive field is observed for RE = Dy (1000 Oe). For the maximum x of Yb14−xRExMnSb11 there are enough carriers for the Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism of magnetic coupling via conduction electrons to still be valid in describing the ferromagnetic ordering.

EuGa4 hosts a magnetic Eu2+ sublattice surrounded by a network of covalently-bound Ga atoms with the BaAl4 structure type (space group I4/ m m m ). In this study, we present the synthesis and characterization of three new single crystal substitutional series Eu A x 1 − x Ga4 with A ​= ​Ca, Sr, or La. X-ray diffraction and resistivity measurements show that Ca substitution induced a structural phase transition from the tetragonal crystal structure at high temperatures to the monoclinic crystal structure (CaGa4 type, space group C2/m) at low temperatures and suppressed the antiferromagnetic ordering temperature to 8.8 ​K for x ​= ​0.45. Comparatively, La or Sr substitution maintained the tetragonal crystal structure and suppressed the antiferromagnetic ordering temperatures to 6.7 ​K and 1.6 ​K for (A, x) = (La, 0.37) and (Sr, 0.91), respectively. In addition to suppressing the magnetic order, magnetization and specific heat measurements indicate the onset of anisotropic metamagnetic transitions in (La, 0.18), (La, 0.37), and (Sr, 0.63), along with an incommensurate-to-commensurate magnetic transition in (Sr, 0.38). By comparing these effects of doping EuGa4, we show how size, disorder, and charge determine the structure-physical property relations in EuGa4.

The compounds, Yb14−xTmxMnSb11 (0

Single crystals of Ce3Ni25.75Ru3.16Al4.1B10 were obtained from a process in which a polycrystalline sample of CeRu2Al2B was annealed in an excess of a Ni–In flux. The initial phase, CeRu2Al2B, does not recrystallize, instead, crystals of a new phase, Ce3Ni25.75Ru3.16Al4.1B10, could be isolated once the flux was removed. The title compound crystallizes in the tetragonal space group P4/nmm (No. 129) with a=1139.02(8), c=801.68(6) pm (c/a=0.70) in the Nd3Ni29Si4B10 structure type. Electrical resistivity measurements reveal metallic behavior with a minimum of 700 µΩ cm and a small residual resistivity ratio of RRR=1.4 indicating a large amount of disorder scattering. The cerium atoms are either in the 4+ or an intermediate valence state with a valence fluctuation temperature far above room temperature.

Samples with the type-I clathrate composition Ba{sub 8}Ni{sub x}Si{sub 46-x} have been synthesized and their structure and thermoelectric properties characterized. Microprobe analysis indicates the Ni incorporation to be 2.62{

Phase stability of the type-I clathrate compound Ba_(8)Al_(x)Si_(46−x) and the thermoelectric property dependence on chemical composition are presented. Polycrystalline samples were prepared by argon arc melting and annealing. Results of powder X-ray diffraction and electron microprobe analysis show that the type-I structure is formed without framework deficiency for 8≤x≤15. Lattice constant a increases linearly with the increase of x. Thermoelectric properties were measured for x=12, 14 and 15. The Seebeck coefficients are negative, with the absolute values increasing with x. The highest figure of merit zT=0.24 was observed for x=15 at T=1000 K, with carrier electron density n=3×10^(21) cm^(−3). A theoretical calculation based on the single parabolic band model reveals the optimum carrier concentration to be n~4×10^(20) cm^(−3), where zT~0.7 at T=1000K is predicted.

The title compound was prepared as single crystals using an aluminum flux technique. Single crystal and powder X-ray diffraction indicate that this composition crystallizes in the clathrate type-I structure, space group Pm3n. Electron microprobe characterization indicates the composition to be Ba_(8−y)Sr_yAl_(14.2(2))Si_(31.8(2)) (0.77

Na4Si4 is a Zintl salt composed of Na+ cations and Si 4 4 − tetrahedral anions and is a unique solid-state precursor to clathrate structures and nanomaterials. In order to provide opportunities for the synthesis of complex materials, phosphorus was explored as a possible substituent for silicon. Phosphorus doped sodium silicides Na4Si4−xPx (x≤0.04) were prepared by reaction of Na with the mechanically alloyed Si4−x:Px (x=0.04, 0.08, 0.12) mixture in a sealed Nb tube at 650 °C for 3 days. Energy dispersive X-ray spectroscopy confirms the presence of P in all products. Powder X-ray diffraction patterns are consistent with the retention of the Na4Si4 crystal structure. As the amount of P increases, a new peak in the diffraction pattern that can be assigned to black phosphorus is apparent above the background. Raman and solid-state NMR provide information on phosphorus substitution in the Na4Si4 structure. Raman spectroscopy shows a shift of the most intense band assigned to the Si 4 4 − ν1 (A1) mode from 486.4 to 484.0 cm−1 with increasing P, consistent with P replacement of Si. Differential nuclear spin-lattice relaxation for the Si sites determined via 29Si solid-state NMR provides direct evidence for Si–P bonding in the (Si1−xPx)4− tetrahedron. The 23Na NMR shows additional Na…P interactions and the 31P NMR shows two P sites, consistent with P presence in both of the crystallographic sites in the (Si4)4− tetrahedron.

Single crystals of SrAl_2Si_2 were synthesized by reaction of the elements in an aluminum flux at 1000 °C. SrAl_2Si_2 is isostructural to CaAl2Si2 and crystallizes in the hexagonal space group P–3m1 (90 K, a=4.1834 (2), c=7.4104 (2) A, Z=1, R1=0.0156, wR2=0.0308). Thermal analysis shows that the compound melts at 1020 °C. Low-temperature resistivity on single crystals along the c-axis shows metallic behavior with room temperature resistivity value of 7.5 mΩ cm. High-temperature Seebeck, resistivity, and thermal conductivity measurements were made on hot-pressed pellets. The Seebeck coefficient shows negative values in entire temperature range decreasing from −78 μV K^(−1) at room temperature to −34 μV K^(−1) at 1173 K. Seebeck coefficients are negative indicating n-type behavior; however, the temperature dependence is consistent with contribution from minority p-type carriers as well. The lattice contribution to the thermal conductivity is higher than for clathrate structures containing Al and Si, approximately 50 mW cm^(−1) K, and contributes to the overall low zT for this compound.

High purity NaGe was directly prepared by a low-temperature reaction of NaH and Ge. The product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. This material is a useful starting reagent for the preparation of Ge nanoparticles. Hydrogen-terminated germanium (Ge) nanoparticles were prepared by reaction of NaGe with NH4Br. These Ge nanoparticles could be prepared as amorphous or crystalline nanoparticles in quantitative yields and with a narrow size distribution. The nanoparticles were functionalized via thermally initiated hydrogermylation with 1-eicosyne, CH3(CH2)17C≡CH to produce alkyl-terminated Ge nanoparticles. The modified Ge nanoparticles were characterized by powder XRD, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) and Raman spectroscopy, and photoluminescence (PL) spectroscopy. The alkyl-functionalized Ge nanoparticles can be expected to have promising applications in many technological and biological areas.

Mg3Sb2 has been prepared by direct reaction of the elements. Powder X-ray diffraction, thermal gravimetric, differential scanning calorimetery, and microprobe data were obtained on hot pressed samples. Single phase samples of Mg3Sb2 were prepared and found to contain oxygen at the grain boundaries and to lose Mg and oxidize at temperatures above 900 K. Thermoelectric properties were characterized by Seebeck, electrical resistivity, and thermal conductivity measurements from 300 to 1023 K, and the maximum zT was found to be 0.21 at ∼875 K.

The compound Ca14MnP11 crystallizes in the Ca14AlSb11 structure type with the tetragonal space group I 4 1 / acd ( Z = 8 ) and lattice parameters of a = 15.3255 ( 7 ) A , c = 20.7565 ( 9 ) at 90 K. The structure consists of MnP49− tetrahedron, P37− trimer, 4 P3− isolated anions and 14 Ca2+ cations. Similar to other compounds of this structure type containing phosphorous, the P37− trimer has a central P atom that is best modeled in the structure as being equally split between two sites. In addition, there is no additional distortion of the manganese-containing tetrahedron compared with the main group analog, Ca14GaP11, suggesting that the Mn oxidation state is Mn2+. Temperature-dependent magnetic susceptibility shows that the compound is paramagnetic over the entire temperature range measured (2–300 K). The data can be fit with a modified Curie–Weiss law and provide an effective magnetic moment of 5.80 (2) B.M. with a Weiss constant of −2.13(2) K and χ 0 = - 9 ( 1 ) × 1 - 5 emu / mol . This moment is significantly higher than those measured for any of the Mn-containing analogs and is consistent with Mn2+. This result will be discussed in light of the electron counting scheme for Mn compounds of the Ca14AlSb11 structure-type.

A new rare-earth rich Zintl phase Yb11GaSb9 was synthesized by direct fusion of the corresponding elements, and large single crystals of the compound were obtained from high temperature flux synthesis. Its crystal structure was determined by single-crystal X-ray diffraction to be orthorhombic in the non-centrosymmetric space group Iba2 (No. 45), Z = 4 ( R 1 = 3.24 % , w R 2 = 6.40 % ) with a = 11.7257 ( 12 ) A , b = 12.3204 ( 13 ) A , c = 16.633 ( 2 ) A measured at 90(3) K. The structure belongs to the Ca11InSb9-type and can be viewed as built of isolated Sb4-tetrahedra centered by Ga, Sb-dimers and isolated Sb anions, which are separated by Yb2+ cations. Electron count according to the Zintl formalism suggests that the phase is electron-precise and charge-balanced, which is supported by the virtually temperature-independent magnetization for Yb11GaSb9. Electrical resistivity data from 2 to 400 K confirm that Yb11GaSb9 is a small band-gap semiconductor with room temperature resistivity ρ 298 = 45.1 m Ω cm , and low-temperature resistivity at 2 K ρ 2 = 1.9 Ω cm . As such, Yb11GaSb9 and related compounds might be promising materials for thermoelectric applications, and currently, efforts to synthesize new members of this family and test their thermoelectric performance are under way.

Measurements of core and valence electronic states of single crystals of the rare earth transition metal Zintl phases Yb14MnSb11 and Yb14ZnSb11 were performed using the X-ray photoelectron spectroscopy station of Beamline 7 at the Advanced Light Source. Sample surfaces of Yb14MnSb11 and Yb14ZnSb11 were measured as received, after Ar+ ion bombardment, and after cleaving in situ. The single crystal structure of Yb14ZnSb11 is also reported. Both compounds are air-sensitive and show Yb3+ due to surface oxidation. In the case of Yb14MnSb11, there is no evidence for Yb3+ that would be intrinsic to the sample, consistent with previously reported X-ray magnetic circular dichroism studies. Detailed analyses of the Yb14ZnSb11 surfaces reveal a significant contribution of both Yb3+ and Yb2+ 4f states in the valence band region. This result is predicted for the Zn analog by Zintl counting rules and support the mixed valency of Yb for Yb14ZnSb11. Further detailed analysis of the core and valence band structure of both Yb14MnSb11 and Yb14ZnSb11 is presented.

The magnetic ordering of the tetragonal Ca 14 MnSb 11 compound (space group I 4 1 / acd ) has been determined by high-resolution neutron diffraction on powder samples. Neutron data were obtained at temperatures of 1.4, 10, 95 K, and room temperature. Refinement of the magnetic structure reveals a ferromagnetic ordering of Mn magnetic moments lying in the a – b plane below the T C of 63 K. The low-temperature-ordered magnetic moment on the Mn ion is 3.4(2) μ B at 1.4 K. The results are confirmed by magnetic susceptibility measurements, which show that the easy magnetization direction of the compound is perpendicular to the c -axis and the system orders ferromagnetically at 63 K, in good agreement with neutron diffraction results. A large negative magnetoresistance effect (Δ ρ / ρ ( H )=−34.4%) at the magnetic transition temperature is observed in applied magnetic fields up to 6 T.

Large single crystals of EuMn2P2 were grown from a tin flux whose melt composition and reaction temperature profile were optimized to avoid impurity phases. The crystal structure of EuMn2P2 is of the CaAl2Si2 structure type. The structure was determined by single-crystal X-ray crystallography, with the unit cell in the trigonal lattice, a=4.1294(3) A and c=6.9936(8) A, at T=90 K (Z=1, R1=0.0239, wR2=0.0632) and belongs to the P 3 m1 (#164) space group. Temperature-dependent magnetic susceptibility, resistivity, and neutron diffraction measurements on single crystals indicate that EuMn2P2 is an antiferromagnetic insulator with a Neel temperature of 16.5±0.25 K. The Eu spins order in a simple magnetic structure where the spins in the a–b plane are aligned ferromagnetically; these ferromagnetic planes are stacked antiferromagnetically along the c-axis.

The new pseudo-binary intermetallic compound, Ti 11 (Sb,Sn) 8 , has been synthesized by reacting Ti and Sb in a Sn flux at 1100°C and its structure determined from both single-crystal X-ray and neutron diffraction data (orthorhombic, Pnma , Z=4, X-ray diffraction at 90 K: a =14.6877(6) A, b =5.5677(2) A, c =17.7207(7) A, V =1449.14(10) A 3 , neutron diffraction at room temperature: a =14.677(6) A, b =5.577(3) A, c =17.716 (6) A, V =1450(1) A 3 ). The structure contains two differently oriented repeating layers and interstitial atoms that are closely connected to make linear chains aligned along the crystal b axis. The compound exhibits mixed site occupancies of Sb and Sn on the anion sites. The phase width (Sb/Sn ratio=0.98–1.40) was determined by microprobe elemental analysis. The electrical resistivity of a single crystal as a function of temperature is anisotropic ( ρ //b =1∼2×10 −1 mΩ·cm, ρ ⊥b =0.5×10 −1 mΩ·cm) and confirms that this compound is metallic. Magnetic susceptibility measurements show Pauli paramagnetism.

The compounds Eu16Sb11 and Eu16Bi11 have been prepared from the elements in Ta containers by heating at 1100°C and then slowly cooled to 1000°C over 4 days.These compounds are isostructural with the Zintl-phase Ca16Sb11 and crystallize in the tetragonal space group P 4 21m (Z=2). The structures were determined from single-crystal X-ray data (T=143 K) for Eu16Sb11 (a=12.674 (2) A, c=11.720 (2) A, R1=4.04% wR2=0.84%), and Eu16Bi11 (a=12.885 (2) A, c=11.883 (4) A, R1=6.09%, wR2=15.24%). The Ca16Sb11 structure type can be described as pairs of face-shared square antiprisms that are joined by means of a square prism to form a columnar chain composed of Ca2+ cations and centered by Sb anions along the c axis. The columns are associated by means of Ca–Ca bonds that alternate long and short along the c axis in a ladder-like fashion. Along the a and b axes, there is an intergrowth of square prism, antiprism columns alternating with columns of face-sharing hexagonal antiprisms. The structures of these Eu compounds are compared with those of Ca16Sb11. Temperature-dependent resistivity of Eu16Sb11 indicates that it is a semiconductor. Magnetization measurements show that Eu16Sb11 and Eu16Bi11 are paramagnetic. The effective moment in the paramagnetic state for Eu16Sb11 is μexp=32.2 (1) μB per formula unit (8.06 (3) μB/Eu atom) and for Eu16Bi11, μexp=33.6 (2) μB/formula unit (8.40 (6) μB/Eu atom), consistent with divalent Eu2+ cations (μeff=7.94 μB/Eu atom).

The structure of Na 2 Ti 2 Sb 2 O has been investigated by temperature-dependent powder neutron diffraction. Na 2 Ti 2 Sb 2 O crystallizes in I 4/ mmm symmetry. The structure of this phase can be viewed as an anti-K 2 NiF 4 type where Ti 3+ ion is located between two oxygen atoms forming a square-planar lattice. Powder neutron diffraction studies of Na 2 Ti 2 Sb 2 O indicate that this compound has a structural distortion in the [Ti 2 Sb 2 O] 2− layer at T ≈120 K. This transition corresponds well to the previously reported anomalous transition temperature of the magnetic susceptibility and electronic resistivity. Several models to explain the data are presented and discussed.

Spin-gap behavior has been observed for the first time in the layered tetragonal compound Na 2 Ti 2 Sb 2 O. Na 2 Ti 2 Sb 2 O shows a sharp discontinuity in magnetic susceptibility at 150 K, reminisent of behavior observed in the spin–Peierls compound CuGeO 3 . Na 2 Ti 2 Sb 2 O also shows a discontinuity in temperature-dependent resistivity at the magnetic transition and metallic behavior for all other temperatures, 5.7 mΩ·cm at room temperature. Ti–Sb–Ti superexchange is proposed to be favored over Ti–O–Ti superexchange, based on the high-temperature magnetic susceptibility data and on the identity of the magnetic orbitals.

A Mn 2 P 2 ( A = Sr, Ba) is an example of a composition that can assume a different structure type depending on the identity of the cation. BaMn 2 P 2 crystallizes in the ThCr 2 Si 2 structure type ( I 4/ mmm ), and SrMn 2 P 2 crystallizes in the CaAl 2 Si 2 structure type ( P 3 m 1). Temperature-dependent magnetic susceptibility, neutron diffraction, and resistivity measurements were obtained for the two compounds. Neutron diffraction shows that BaMn 2 P 2 exhibits long-range antiferromagnetic ordering at room temperature. Mn(II) is high spin, with ordered moment 4.2 (1) μ B , and the magnetic structure is type G. Magnetic susceptibility measurements show no maxima up to 750 K, indicating that the transition temperature, T c , is very high. SrMn 2 P 2 is antiferromagnetic below T c = 53(1) K, as determined from the temperature dependence of the magnetic reflections. There are two distinct sets of magnetic reflections distinguished by different temperature dependencies and indexing schemes. The magnetic structure is evidently complex, but was not determined. Both compounds exhibit semiconducting resistivity behavior with E a = 0.073(1) eV (BaMn 2 P 2 ) and 0.0129(2) eV (SrMn 2 P 2 ). The properties of BaMn 2 P 2 and SrMn 2 P 2 are discussed in light of their structures and previous theoretical investigations by Zheng and Hoffmann.

A 14 AlSb 11 ( A = Ca, Sr, Ba) is synthesized by reacting the elements in stoichiometric amounts at high temperature (1250°C). Single-crystal X-ray diffraction data (130 K: a = 17.493 (4) A, c = 23.480 (8) A (Sr); a = 18.293 (2) A, c = 24.222 (9) A (Ba)) were refined (tetragonal, I 4 1 / acd (142), Z = 8; R = 4.02%, R w = 4.26% (Sr); R = 3.71%, R w = 4.34% (Ba)) and showed these compounds to be isostructural to Ca 14 AlSb 11 . Single-crystal X-ray and microprobe data indicate that these compounds are slightly deficient in Al. Temperature-dependent resistivity measurements show that these materials are intrinsic semiconductors with activation energies of 0.0143, 0.0667, and 0.4814 eV for the Ca, Sr, and Ba analogs, respectively.

Two compounds, BaT4Sb12 (T = Fe, Ru), have been synthesized using high temperature methods. These compounds crystallize in the cubic LaFe4P12 structure type. Two methods are described for the synthesis of BaFe4Sb12. Single crystals of BaFe4Sb12 can be prepared by reacting BaSb, Fe, and Sb in a 1:4:18 (Ba:Fe:Sb) molar ratio (method I). Single crystal X-ray diffraction data (room temperature, a = 9.200(3) A) for BaFe4Sb12 prepared by Method I were refined (cubic, Im 3 (No. 204), Z = 2, R = 1.96%, Rw = 1.73% for 179 independent reflections). BaFe4Sb12 can also be prepared in ≥80% yield from the reaction of stoichiometric amounts of Ba2Sb3, FeSb2, and Sb (method II). Low temperature (130 K, a = 9.188(2)) single crystal X-ray diffraction data on BaFe4Sb12 crystals produced from Method II were also measured and refined (R = 2.29%, Rw = 2.45% for 179 independent reflections). The structure of BaFe4Sb12 will be compared to that of the LaFe4Sb12 and CoSb3.

AMn[sub 2]P[sub 2] (A = Sr, Ba) is an example of a composition that can assume a different structure type, depending on the identity of the cation. BaMn[sub 2]P[sub 2] crystallizes in the ThCr[sub 2]Si[sub 2] structure type, whereas SrMn[sub 2]P[sub 2] crystallizes in the CaAl[sub 2]Si[sub 2] structure type. These compounds have been characterized by temperature-dependent magnetic susceptibility, neutron diffraction, and resistivity. The results indicate that extended Hueckel calculations cannot adequately account for the electronic or magnetic properties of these compounds.

Corrigendum to ‘‘Structure and high temperature thermoelectric properties of SrAl2Si2’’ [J. Solid State Chem. 182 (2009) 240–245] Susan M. Kauzlarich , Cathie L. Condron , Jonathan K. Wassei , Teruyuki Ikeda , G. Jeffrey Snyder b a Department of Chemistry, University of California, One Shields Avenue, Davis, CA 95616, USA b Materials Science, California Institute of Technology, 1200 California Boulevard, Pasadena, CA 91125, USA