Diffractometer Data Research Articles

Segregation of Calcium and Magnesium into Different Substructures. Ca4Ag0.948Mg and Other Compounds with Gd4RhIn-type Structure

The metal-rich compounds R4PdMg (R = Ca, Eu, Tb-Lu), R4AgMg (R = Ca, Yb), R4PtMg (R = Eu, Tb-Lu), and R4AuMg (R = Ca, Eu, Yb) were synthesized by induction melting of the elements in sealed tantalum tubes in a water-cooled sample chamber. All samples were characterized by powder X-ray diffraction. The structures of Ca4Ag0.948Mg and Yb4PdMg were refined on the basis of single-crystal X-ray diffractometer data: Gd4RhIn type, F 4̄3m, a = 1434.6(1) pm, wR2 = 0.0269, 523 F2 values, 18 variables for Yb4PdMg and a = 1485.78(7) pm, wR2 = 0.0188, 617 F2 values, 20 variables for Ca4Ag0.948Mg. For the first time small defects on the 16e transition metal site of a Gd4RhIn-type compound have been observed, and the first compounds of this structure type with the divalent rare earth elements europium and ytterbium as well as with calcium are reported. The striking structural motif of these compounds (exemplary for Ca4Ag0.948Mg) is the clear segregation of two alkaline earth elements into two different substructures, calcium forming trigonal prisms around the silver atoms and magnesium forming covalently bonded tetrahedra (Mg-Mg 328 pm). The latter are embedded in larger cavities of the adamantane-like three-dimensional network of edge- and corner-sharing AgCa6 trigonal prisms. This is evident from the chemical bonding analysis of the electronic structure by ab initio calculations. The density of states shows s-like metallic conductivity with an active role played by the Ag d states within the valence band and for the bonding with calcium. Temperature-dependent magnetic susceptibility data of Eu4PdMg and Eu4PtMg show Curie-Weiss behavior above 230 K with experimental magnetic moments of 7.94(1) and 8.00(1) μB per Eu atom for the palladium and platinum compound, respectively. Ferromagnetic ordering is detected at the comparatively high Curie temperatures of 150.1(5) (Eu4PdMg) and 139.1(5) (Eu4PtMg) K. Magnetization measurements at 3 K show full parallel spin alignment and the typical behavior of soft ferromagnets.

CaBe2Ge2 type phosphides REIr2P2 (RE = La–Nd, Sm) and arsenides REIr2As2 (RE = La–Nd): synthesis, structure, and solid state NMR spectroscopy

The phosphides REIr(2)P(2) (RE = La-Nd, Sm) and arsenides REIr(2)As(2) (RE = La-Nd) were synthesized by a ceramic route via precursor compounds REIr(2) with phosphorus and arsenic, respectively. Well-shaped single crystals were obtained from lead and bismuth fluxes, respectively. The nine pnictides crystallize with the tetragonal CaBe(2)Ge(2) type structure, space group P4/nmm. The structures of CeIr(2)P(2), SmIr(2)P(2), LaIr(2)As(2) and CeIr(2)As(2) were refined from single crystal X-ray diffractometer data. The structures are composed of three-dimensional [Ir(2)P(2)] and [Ir(2)As(2)] networks in which the rare earth atoms fill cavities of coordination number 16 (8 P + 8 Ir). The phosphorus and arsenic atoms have tetrahedral and square pyramidal iridium coordination. Temperature dependent magnetic susceptibility measurements show intermediate cerium valence for CeIr(2)P(2). The rare-earth and phosphorus local environments in LaIr(2)P(2) are characterized further by (139)La and (31)P single and double resonance solid state nuclear magnetic resonance (NMR) spectroscopy. Strong (31)P Knight shifts and extremely short spin-lattice relaxation times indicate that the bonding character of the phosphide species is strongly metallic. The two crystallographically distinct phosphorus sites are well-resolved in the (31)P magic-angle spinning (MAS) spectrum and also differ significantly with respect to their effective magnetic shielding anisotropies. Unambiguous site assignments are accomplished on the basis of homonuclear (31)P-(31)P magnetic dipole-dipole interactions, which can be measured in a site-resolved fashion in this compound using static (31)P spin echo decay spectroscopy. The highly symmetric La environment in LaIr(2)P(2) is characterized by a sharp (139)La MAS-NMR spectrum, revealing rather weak nuclear electric quadrupole coupling. Furthermore, a second local environment is detected, which is characterized by stronger quadrupolar coupling and similar dipolar coupling strength with (31)P as the regular site, according to (139)La{(31)P} rotational echo double resonance (REDOR) NMR results. On the basis of these data we attribute this site to a La species next to a phosphorus vacancy. From the signal area of this resonance we deduce a composition LaIr(2)P(1.90).

Accurate determination of the low-angle structure factors of βNiAl by powder X-ray diffraction

An improved approach to the analysis of powder X-ray diffractometer data obtained from crystalline materials has been developed and applied to diffraction data obtained from powdered Ni-50.51 at% Al (B2 cubic structure) with Cu-K radiation. Great care was taken to ensure the accuracy of the alloy chemical analysis and very fine powders (less than 5 µm particle size) were used to minimize the effects of preferred orientation and extinction. As a result it was found that, even when only a few reflections are available for study and anomalous dispersion corrections and thus extinction corrections are somewhat larger than normal due to excessive fluorescence, it is possible to obtain accurate low-angle structure factor values that give information about crystal bonding. In the case of NiAl, this appears to be predominantly ionic. These results mean that any laboratory that has a basic powder X-ray diffractometer can adopt this approach and make accurate measurements of the structure factors of many crystalline solids.

A Further Extension of Pnictide Oxide Chemistry – Synthesis and Structure of La2AuP2O

AbstractThe phosphide oxide La2AuP2O was synthesized from lanthanum filings, dried La2O3, gold pieces, and ground red phosphorus in the ideal 1.33:0.33:1:2 ratio in an evacuated silica tube at 1473 K. Small single crystals were obtained by recrystallization in a NaCl/KCl flux. The structure was determined on the basis of single‐crystal X‐ray diffractometer data: new type, C2/m, a = 1537.3(3), b = 427.39(8), c = 1009.2(2) pm, β = 131.02(1) °, wR2 = 0.046, 1102 F2 values, 38 variables. La2AuP2O contains two striking structural motifs: The oxygen atoms are located in La4 tetrahedra. The latter are cis‐edge‐shared forming polymeric cationic [La2O]4+ chains. These cationic units are separated and charge‐balanced by [AuP2]4– polyanions which have monovalent gold in distorted trigonal planar phosphorus coordination. Two crystallographically independent phosphorus sites occur in the polyanion, i.e. isolated P3– besides dumb‐bells P24– (P2–P2 223 pm). La2AuP2O, which crystallizes in the form of ruby red transparent crystals, is an electron precise phosphide oxide (4La3+)(2Au+)(2P3–)(P24–)(2O2–).

Benz[cd]indol-2(1H)-one at 298 and 100 K

Weakly diffracting crystals of benz[cd]indol-2(1H)-one (naphtholactam), C(11)H(7)NO, were unsuitable for data collection by early photographic methods. However, a diffractometer data set collected at room temperature in 1989 was solved and refined. The peak scans were broad, and the results indicated disorder or a satellite crystal. Recent data collection (on another crystal from the same sample) with an area detector at 100 K revealed the same disorder, and made it possible to refine two different, more complete, disorder models. Both models assume an occasional 180° rotation of the nearly planar centrosymmetric cis-lactam dimer. The refinements differ, especially in the anisotropic displacement parameters for the -C(=O)-NH- portion of the molecule. Both models at 100 K give a C-N (`amide') bond distance of 1.38 Å, about 0.04 Å longer than the average distance in saturated γ-lactams in the Cambridge Structural Database. Cohesive packing interactions between molecules include opposing-dipole dimers; the packing may explain the 10:1 ratio favoring the major-occupancy molecule.

Ternary Indides Eu2Pd2In and Eu2Pt2In

AbstractThe indides Eu2Pd2In and Eu2Pt2In were synthesized from the elements in sealed tantalum tubes in an induction furnace. The samples were characterized by powder X‐ray diffraction. The structures were refined on the basis of single‐crystal X‐ray diffractometer data: HT‐Pr2Co2Al type, C2/c, a = 1035.7(2), b = 592.9(1), c = 823.6(2) pm, β = 104.26(1) °, wR2 = 0.026, 1075 F2 values, 25 variables for Eu2Pd2In and a = 1017.2(2), b = 588.7(1), c = 826.5(1) pm, β = 103.76(1) °, wR2 = 0.062, 706 F2 values, 25 variables for Eu2Pt2In. The indium atoms have four platinum (palladium) neighbors in strongly distorted tetrahedral coordination at Pt–In and Pd–In distances ranging from 273 to 275 pm. These InPd4/2 and InPt4/2 units are condensed via common edges to infinite InPd2 and InPt2 chains, which are surrounded by the europium atoms. The chains form the motif of hexagonal rod packing.

45Sc Solid State NMR studies of the silicides Sc TSi ( T=Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt)

The silicides Sc TSi ( T=Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) were synthesized by arc-melting and characterized by X-ray powder diffraction. The structures of ScCoSi, ScRuSi, ScPdSi, and ScIrSi were refined from single crystal diffractometer data. These silicides crystallize with the TiNiSi type, space group Pnma. No systematic influences of the 45Sc isotropic magnetic shift and nuclear electric quadrupolar coupling parameters on various structural distortion parameters calculated from the crystal structure data can be detected. 45Sc MAS-NMR data suggest systematic trends in the local electronic structure probed by the scandium atoms: both the electric field gradients and the isotropic magnetic shifts relative to a 0.2 M aqueous Sc(NO 3) 3 solution decrease with increasing valence electron concentration and within each T group the isotropic magnetic shift decreases monotonically with increasing atomic number. The 45Sc nuclear electric quadrupolar coupling constants are generally well reproduced by quantum mechanical electric field gradient calculations using the WIEN2k code.

Ternary stannides RETi 6Sn 4 ( RE = Y, Gd–Tm, Lu) with rhombohedral LiFe 6Ge 4 type structure

The stannides RETi 6Sn 4 ( RE = Y, Gd–Tm, Lu) were synthesized from the elements by arc-melting and subsequent annealing in an induction furnace. All samples were characterized by powder X-ray diffraction. The structures of TmTi 6Sn 4 and LuTi 6Sn 4 were refined from single crystal diffractometer data: LiFe 6Ge 4 type, R 3 ¯ m , a = 576.6 (1), c = 2271.4 (3) pm, w R = 0.0416, 538 F values, 18 parameters for Tm 0.86Ti 6Sn 4.14 and a = 576.4 (1), c = 2260.6(2) pm, w R = 0.0676, 666 F values, 18 parameters for Lu 0.92Ti 6Sn 4.08. Both 3 a Wyckoff sites show a small degree of RE/Sn mixing. The RETi 6Sn 4 structure is composed of two basic structural motifs which show a layered arrangement. Motif A are layers of edges-sharing RESn 8/2 hexagonal bipyramids (286–333 pm Lu–Sn in Lu 0.92Ti 6Sn 4.08) and motif B Kagomé networks of the titanium atoms with 282–295 pm Ti–Ti in Lu 0.92Ti 6Sn 4.08. ABB packages of these building units are stacked in the rhombohedral sequence. Temperature dependent magnetic susceptibility measurements show Curie–Weiss behavior in the high-temperature regime and no magnetic ordering down to 3 K. A 119Sn Mössbauer spectrum of the TmTi 6Sn 4 sample resolves the two crystallographically independent tin sites; weak (Δ E Q = 0.44(2) mm/s, δ = 1.82(1) mm/s) quadrupole splitting for the Sn2 and large (Δ E Q = 1.42(2) mm/s, δ = 1.92(1) mm/s) quadrupole splitting for the Sn1 site.

New rare earth-rich aluminides and indides with cubic Gd4RhIn-type structure

The series of rare earth metal (RE)-rich intermetallics RE 4 TAl and RE 4 TIn (T = Ru, Rh, Ir) were synthesized by induction melting of the elements in sealed tantalum tubes. These compounds crystallize with the cubic Gd4RhIn-type structure, space group $$F\bar{4}3m$$ . The structures of eight crystals (including the isotypic compounds Ce4RuMg and Ce4RuCd) have been refined from X-ray single-crystal diffractometer data. The structures are composed of condensed RE 6 T trigonal prisms which form a rigid network with adamantane-like topology. Large cavities within these networks are filled with empty RE 6 octahedra and Al4, In4, Mg4, or Cd4 tetrahedra, respectively. Some of the RE 4 TAl and RE 4 TIn show small homogeneity ranges that result from small degrees of Al/T and In/T mixing on the 16e sites. All cerium compounds show small anomalies in the plots of the cell volumes. This is confirmed by temperature-dependent magnetic susceptibility measurements. Ce4RuMg, Ce4RuCd, Ce4RuAl, and Ce4RuIn show intermediate cerium valence and no magnetic ordering down to 3 K. Ce4RhAl shows essentially trivalent cerium.

La3Pd4Zn4 and La3Pt4Zn4 with a different coloring of the Gd3Cu4Ge4-type structure

The intermetallic zinc compounds La3Pd4Zn4 and La3Pt4Zn4 were synthesized by induction melting of the elements in sealed tantalum tubes. The structures were refined from X-ray single-crystal diffractometer data: Gd3Cu4Ge4 type, Immm, a = 1,440.7(5), b = 743.6(2), c = 419.5(2) pm, wR 2 = 0.0511, 353 F 2 for La3Pd4Zn4; and a = 1,439.9(2), b = 748.1(1), c = 415.66(6) pm, wR 2 = 0.0558, 471 F 2 for La3Pt4Zn4 with 23 variables per refinement. The palladium (platinum) and zinc atoms build up a three-dimensional polyanionic [Pd4Zn4] (260–281 pm Pd–Zn) and [Pt4Zn4] (260–279 pm Pt–Zn) network in which the lanthanum atoms fill cavities of CN 14 (6 Pd/Pt + 8 Zn for La1) and CN 12 (6 Pd/Pt + 6 Zn for La2), respectively. The copper position of the Gd3Cu4Ge4 type is occupied by zinc and the two crystallographically independent germanium sites by palladium (platinum), a new coloring pattern for this structure type. Within the [Pd4Zn4] and [Pt4Zn4] the Pd2 and Pt2 atoms form Pd2–Pd2 (291 pm) and Pt2–Pt2 (296 pm) dumbbells. The structures of La3Pd4Zn4 and La3Pt4Zn4 are discussed with respect to the prototype Gd3Cu4Ge4 and the Zintl phase Sr3Li4Sb4. Temperature-dependent magnetic susceptibility measurements indicate diamagnetism for La3Pt4Zn4 and Pauli paramagnetism for La3Pd4Zn4.

Metal-rich phosphides RE5Ir 19P 12 with Sc 5Co 19P 12 type structure

The iridium-rich phosphides RE 5Ir 19P 12 ( RE=Sc, Y, La–Nd, Sm–Lu) with Sc 5Co 19P 12 type structure, space group P62̄ m were synthesized by solid state reactions of the elements in tantalum crucibles. Well shaped single crystals were obtained in bismuth fluxes. All phosphides were characterized on the basis of X-ray powder data. The structures of RE 5Ir 19P 12 with RE=Sc, La, Ce, Dy, Er, Tm, and Yb were refined from single crystal diffractometer data. The complex structure of these phosphides can be described by an intergrowth of simpler ThCr 2Si 2 and SrPtSb related slabs. Striking structural motifs of the RE 5Ir 19P 12 structures are slightly distorted tricapped trigonal prisms of the metal atoms around the phosphorus atoms. The iridium and phosphorus atoms build up three-dimensional [Ir 19P 12] polyanionic networks (230–286 pm Ir–P and 282–296 pm Ir–Ir in La 5Ir 19P 12) which leave cavities of coordination numbers 16 and 15 for the rare earth atoms.

RE8Rh 17Sb 14 ( RE = La, Ce, Pr, Nd) with a CaBe 2Ge 2-related superstructure through rhodium–antimony-ordering and vacancy formation

The new antimonides RE 8Rh 17Sb 14 ( RE = La, Ce, Pr, Nd) were synthesised by arc-melting. Crystals can be grown in a high-frequency furnace. The RE 8Rh 17Sb 14 phases were characterized by powder X-ray diffraction. They crystallize with a tetragonal, CaBe 2Ge 2-related superstructure which was refined for Ce 8Rh 17Sb 14 on the basis of single crystal X-ray diffractometer data: I4 cm, a = 1239.8 (3), c = 2101.8 (8) pm, w R = 0.065, 2924 F values, and 109 parameters. The rhodium and antimony atoms and vacancies show full ordering on the [Be 2Ge 2] substructure, leading to a composition of Ce 8Rh 17Sb 14 CeRh 2.13Sb 1.75. The superstructure formation is discussed on the basis of a group-subgroup scheme together with the related structures of CePt 2+xSb 2−y, CeNi 1.91As 1.94 and URh 1.6As 1.9. Temperature dependent susceptibility measurements show Pauli paramagnetism for La 8Rh 17Sb 14 and Curie–Weiss paramagnetism for RE 8Rh 17Sb 14 ( RE = Ce, Pr, Nd). No magnetic ordering was detected down to 2.5 K.

The binary tin-rich lanthanum stannides La 2Sn 5 and La 3Sn 7—A structural and bond theoretical study

The three tin-rich lanthanum stannides LaSn 3, La 2Sn 5 and La 3Sn 7, which were known only from indexed powder diagrams, have been synthesized from melts of the elements by slow cooling of sealed sample tubes or arc melting and quenching. Their crystal structures were refined from X-ray powder diffractometer data using the Rietveld method. LaSn 3 (cubic, space group Pm 3 ¯ m , a=477.77(1) pm, Z=1, R F 2 = 0.044 ) crystallizes with the common Cu 3Au structure type, which can be described either as an ordered close packing or as a network of [Sn 6] octahedra ( closo clusters) connected via common vertices. The structures of La 2Sn 5 (Ce 2Sn 5 structure type, orthorhombic, space group Cmmm, a=463.85(3), b=3581.3(3), c=469.83(4) pm, Z=4, R F 2 = 0.075 ) and La 3Sn 7 (Gd 3Sn 7 structure type, orthorhombic, space group Cmmm, a=457.83(4), b=2628.40(2), c=467.99(4) pm, Z=2, R F 2 = 0.068 ) , which retain some similarities to ordered close packings as well, show 2D blocks of corner-sharing [Sn 6] octahedra terminated by [Sn 5] square pyramids ( nido clusters). In between these layers, isolated Sn zigzag chains similar to those observed in LaSn (CrB structure type) are interspersed. A simple v.e. count after Zintl and Wade/Jemmis for the polyanionic Sn building blocks resulting from these structure descriptions fits the observed v.e. numbers of the three compounds almost exactly. It is also possible to explain the minima of the tDOS close to E F, which have been calculated within the framework of the FP-LAPW DFT approach. However, the simple assumption of an exclusively Sn- p bonded polyanion would neglect the large Sn–La bonding contributions and the reduced amount of electron transfer from La to Sn when compared to related alkaline earth stannides.

Ternary Stannides RE3Ru4Sn13 (RE = La, Ce, Pr, Nd) – Structure, Magnetic Properties, and 119Sn Mössbauer Spectroscopy

The ternary stannides RE3Ru4Sn13 (RE = La, Ce, Pr, Nd) were obtained by arc-melting of the elements. The polycrystalline samples were characterized by powder X-ray diffraction. The structures of three compounds were refined from single-crystal diffractometer data: Yb3Rh4Sn13 type, Pm3̄n, a = 977.74(3) pm, wR2 = 0.0379, 280 F2 values for La3Ru4Sn13, a = 971.34(9) pm, wR2 = 0.0333, 274 F2 values for Ce3Ru4Sn13, a = 970.68(8) pm, wR2 = 0.0262, 272 F2 values for Nd3Ru4Sn13 with 13 variables per refinement. The structures consist of three-dimensional networks of condensed RuSn6/2 trigonal prisms with the RE (CN 16) and Sn2 (CN 12) atoms in two different types of cavities of the networks. The two crystallographically independent tin sites have been resolved by 119Sn Mössbauer spectroscopy. Temperature-dependent magnetic susceptibility measurements of Ce3Ru4Sn13 gave a reduced magnetic moment of 2.32 μB per Ce atom, indicating intermediate cerium valence. No magnetic ordering was evident down to 3 K.

EuGa2Sb2: a new Zintl phase with four-bonded gallium and three-bonded antimony in a complex three-dimensional [Ga2Sb2] polyanion

The Zintl phase EuGa2Sb2 was synthesized by induction melting of the elements in a sealed tantalum tube. The structure was refined from X-ray single-crystal diffractometer data: new type, Pnma, a = 1834.7(3), b = 432.25(7), c = 674.8(1) pm, wR2 = 0.0377, 875 F 2, and 32 variables. The structure consists of a three-dimensional polyanionic [Ga2Sb2]2– network with Ga 2 4+ dumb-bells (252.1(1) pm Ga1–Ga2) and antimonide anions, leading to the electron-precise description Eu2+[Ga2Sb2]2−. The divalent character of europium was evident from magnetic susceptibility data and 151Eu Mossbauer spectra. The crystal chemical relationship with the structures of EuGa2As2 and BaGa2Sb2 is discussed.

The magnetocaloric properties of GdScSi and GdScGe

The magnetocaloric properties of the ferromagnetic compounds GdScSi (TC = 354(2) K) and GdScGe (TC = 349(2) K) (tetragonal CeScSi-type structure refined from single crystal diffractometer data, space group I4/mmm) have been determined. The field dependence of the magnetic entropy ΔSm change and of the refrigerant capacity RC have been obtained from magnetization measurements. At the TC Curie temperature, ΔSm for GdScSi and GdScGe is respectively equal to 2.5 and 3.3 J/kgGd K for a magnetic field change of 2 T; the values are comparable to those determined previously for Gd7Pd3 and Gd4Bi3 which exhibit also a TC-temperature higher than room temperature. Both microstructural and the analysis of the magnetocaloric response are used to assess the single phase nature of the samples.

Cd4 Tetrahedra and Condensed RE6Rh Trigonal Prisms as Building Units in the Rare Earth-rich Compounds RE15Rh5Cd2 (RE = La, Ce, Pr, Nd)

The rare earth-rich compounds RE15Rh5Cd2 (RE = La, Ce, Pr, Nd) were synthesized by induction melting of the elements in sealed tantalum tubes and characterized by X-ray powder diffraction. The structure of La15Rh5Cd2 was refined from single-crystal diffractometer data: new type, R3m, a = 1016.4(2), c = 4418.7(9) pm, wR2 = 0.0417, 2258 F2, 95 variables. Striking structural motifs in the RE15Rh5Cd2 intermetallics are rhodium-centered trigonal prisms RE6Rh which are condensed via common corners and edges to a complex three-dimensional network which leaves cavities for Cd4 tetrahedra and RE6 octahedra. The structural relationship with the recently discovered structure types Gd4RhIn and Pr23Ir7Mg4 is discussed.

A 121Sb and 151Eu Mössbauer Spectroscopic Investigation of EuCd2X2 (X = P, As, Sb) and YbCd2Sb2

AbstractThe pnictides EuCd2X2 (X = P, As, Sb) and YbCd2Sb2 were synthesized from the elements or a EuCd2 precursor in tantalum tubes. The samples were characterized by powder X‐ray diffraction. The structure of EuCd2As2 was refined on the basis of single‐crystal X‐ray diffractometer data: CaAl2Si2 type, P$\bar{3}$m1, a = 444.99(9), c = 735.0(1) pm, wR2 = 0.0372, 200 F2 values and 10 variables. The two‐dimensional [Cd2X2] networks consist of edge‐sharing CdX4/4 tetrahedra. The networks are separated and charge‐balanced by the europium and ytterbium atoms. Redetermination of the magnetic properties revealed divalent europium and ytterbium. YbCd2Sb2 is diamagnetic. For the europium compounds only one magnetic phase transition is evident, i.e. TC = 11.6 K for EuCd2P2, TN = 9.5 K for EuCd2As2, and TN = 7.4 K for EuCd2Sb2. 151Eu Mössbauer spectra show full magnetic hyperfine field splitting at 4.2 K. A transferred hyperfine field of 7.1 T is evident in the 4.2 K 121Sb spectrum of EuCd2Sb2.

Bismuth flux synthesis and structure of the iridium-rich phosphides RE7Ir 17P 12 ( RE = Y, Gd, Tb, Dy, Ho) with La 7Pd 17P 12 type structure

The iridium-rich phosphides RE 7Ir 17P 12 ( RE = Y, Gd, Tb, Dy, Ho) with La 7Pd 17P 12 type structure, space group C2/ m were synthesized from the elements in bismuth fluxes. The five structures were refined on the basis of X-ray single crystal diffractometer data. These phosphides have six crystallographically independent phosphorus sites which all have coordination number 9 in tricapped trigonal prismatic metal coordination. These prisms are condensed via common rectangular faces within one layer and via the triangular faces perpendicular to the layers. The second striking structural motif is the broad ranges of Ir–Ir distances within the complex iridium substructure. The RE 7Ir 17P 12 phosphides belong to the large series of metal-rich compounds with a metal:non-metal ratio of 2:1.

Synthesis and Structure of the Ternary Vanadate NaMn4(VO4)3

The vanadate NaMn4(VO4)3 was obtained as darkbrown crystals as a side-product during the crystallization of the oxygen-deficient perovskite Na3MnV2O7.5 in an NaCl/KCl flux. NaMn4(VO4)3 crystallizes with the tetragonal (Mg1/2□1/2)Mg4(AsO4)3 type, space group I 4̄2d. The structure was refined from single-crystal diffractometer data: a = 7.0238(2), c = 19.8360(9) Å , R(F) = 0.013, wR(F2) = 0.033, 853 F2 values, and 49 variables. The NaMn4(VO4)3 structure is built up of different sheets stacked perpendicular to the c axis. Na, Mn and V atoms are located in dodecahedra, octahedra and tetrahedra, respectively.