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International audience; X-ray single crystal data for “ThBC2” defined the crystal structure as orthorhombic (space group Pnnm; a = 1.30655(3) nm, b = 0.39757(1) nm, c = 0.36507(1) nm; RF2 = 0.0130) with the correct formula Th2B2C3. According to the new findings phase relations for the Th-B-C system at 1400 °C have been revised confirming the hitherto known thorium-boron-carbon compounds: ThBC, ThB2C and Th3B2C3. The crystal structure of Th2B2C3 as a unique structure type is characterized by a C2-branched infinite chain … B-C1-B-B-C1-B … whereby each boron atom is additionally linked to a C2-atom. Boron atoms are in a typical triangular prismatic metal coordination, C1-atoms center a bi-pyramid, Th4B2, and C2-atoms are surrounded by 5 pyramidal Th-atoms and one B-atom. Density functional theory calculations were made within the pseudopotential approach of VASP utilizing the general gradient approximation for the exchange correlation functional. Structural parameters were optimized resulting in the orthorhombic lattice parameters of a = 1.3144 nm, b = 0.3989 nm, and c = 0.3656 nm. Relativistic calculations by including spin-orbit coupling were performed for the electronic structure. Atomic volumes and charges were computed by the concept of Bader yielding the ionic charges Δq(Th) = +0.99; Δq(B) = +0.61; Δq(C1) = −1.20; Δq(C2) = −1.10. The analysis of the electronic structure shows features of chains and corresponding structural subunits with σ-like bonding. The compound appears weakly metallic with a Sommerfeld constant of γ = 3.12 mJ/(molK2) per formula unit. © 2017 Acta Materialia Inc.

This study is closely related to the chemical interactions in thermoelectric joints of a hot metal electrode with p- and n-type skutterudite. As a result of this work, a first and complete phase diagram has been constructed for the Ti Sb system as well as partial phase diagrams (>65 at.% Sb) for the systems Zr Sb and Hf Sb. Investigations are based on X-ray powder and single crystal analyses (determination of the crystal structure of Ti5Sb8 with Zr2.6Ti2.4Sb8-type, space group I4122; RF = 0.032), electron probe microanalyses (EPMA) and differential thermal analyses (DTA). Physical properties were evaluated for the binary compounds MSb2 (M = Ti, Zr, Hf) comprising electrical resistivity (from 4.2 K to 825 K), specific heat, thermal conductivity and thermal expansion coefficient (from 4.2 K to 300 K), Seebeck coefficient (from 300 K to 825 K) and elastic moduli at 300 K. These data will serve to evaluate the potential of MSb2 compounds (M = Ti, Zr, Hf) for thermoelectric devices, where these phases predominantly appear in the diffusion zones of the hot metal electrode with p- and n-type skutterudite.

The crystal structures of two novel borides in the Ni-Zn-B system, τ5-Ni3Zn2B and τ6-Ni2ZnB, were determined by single crystal X-ray diffraction (XRSC) in combination with selected area electron diffraction in a transmission electron microscope (SAED-TEM) and electron probe microanalysis (EPMA). Both compounds crystallize in unique structure types (space group C2/m, a = 1.68942(8) nm, b = 0.26332(1) nm, c = 0.61904(3) nm, β = 111.164(2)°, RF = 0.0219 for Ni3Zn2B, and space group C2/m, a = 0.95296(7) nm, b = 0.28371(2) nm, c = 0.59989(1) nm, β = 93.009(4)°, RF = 0.0163 for Ni2ZnB). Both compounds have similar building blocks: two triangular prisms centered by boron atoms are arranged along the c-axis separated by Zn layers, which form empty octahedra connecting the boron centered polyhedra. Consistent with the (Ni+Zn)/B ratio, isolated boron atoms are found in τ5-Ni3Zn2B, while B-B pairs exist in τ6-Ni2ZnB. The crystal structure of Ni2ZnB is closely related to that of τ4-Ni3ZnB2, i.e. Ni2ZnB can be formed by removing the nearly planar nickel layer in Ni3ZnB2 and shifting the origin of the unit cell to the center of the B-B pair. The electrical resistivity and specific heat of τ5-Ni3Zn2B reveal the metallic behavior of this compound with an anomaly at low temperature, possibly arising from a Kondo-type interaction. Further analysis on the lattice contribution of the specific heat reveals similarity with τ4-Ni3ZnB2 with some indications of lattice softening in τ5-Ni3Zn2B, which could be related to the increasing metal content and the absence of B-B bonding in τ5-Ni3Zn2B. For the newly found phases, τ5-Ni3Zn2B and τ6-Ni2ZnB as well as for τ3-Ni21Zn2B20 and τ4-Ni3ZnB2 density functional theory (DFT) calculations were performed by means of the Vienna Ab initio Simulation Package (VASP). Total energies and forces were minimized in order to determine the fully relaxed structural parameters, which agree very well with experiment. Energies of formations in the range of -25.2 to -26.9 kJ mol-1 were calculated and bulk moduli in the range of 179.7 to 248.9 GPa were derived showing hardening by increasing the B concentration. Charge transfer is discussed in terms of Bader charges resulting in electronic transfer from Zn to the system and electronic charge gain by B. Ni charge contributions vary significantly with crystallographic position depending on B located in the neighbourhood. The electronic structure is presented in terms of densities of states, band structures and contour plots revealing Ni-B and Ni-Zn bonding features.

The crystal structure of a new natural compound NaCu2Cl3[N3C2H2]2[NH3]2·4H2O, (further denoted I in the text) from a guano deposit located on the Pabellón de Pica Mountain, Iquique Province, Tarapacá Region, Chile, was studied by single-crystal low-temperature (200 K) XRD, R=2.42%. The compound I is orthorhombic, space group P212121; a=19.484(3), b=7.2136(10), c=11.999(4) Å, V=1686.5(7) Å3, Z=4. The crystal structure of I contains zig-zag chains of the corner-sharing Cu(1)-centered octahedra running along the a axis and isolated Cu(2)-centered octahedra connected with the chains via 1,2,4-triazolate anions. This structural fragment is close to that found in the mineral chanabayaite, Cu2(N3C2H2)2Cl(NH3, Cl, H2O, □)4. In contrast to Na-free chanabayaite, in the structure of I Na cations occupy Na(H2O)6 octahedra connected via common edges to form chains parallel to the chains of Cu(1)-centered octahedra. I is the second natural compound, after chanabayaite, with 1,2,4-triazolate anions N3C2H2 – and is assumed to be a protophase of chanabayaite; the latter was presumably formed as a result of Na and Cl leaching and dehydration of I.

Novel FeB-type phases have been evaluated in the systems Ta-{Ti,Zr,Hf}-B either from as cast or arc treated samples by x-ray powder and single crystal diffraction as well as electron probe microanalysis. In each of the three systems the formation of the FeB-type phase suggests a high temperature stabilization of a binary group IV metal monoboride with FeB-type. This holds true for Ti and Hf, while for Zr the single crystal study of (Ta,Zr)B proves that it is a true ternary phase, as no stable monoboride exists in the binary Zr-B system. EPMA analyses reveal that the FeB-type phases Ta{Ti,Zr,Hf}B are formed by substitution of Ta in TaB by rather small amounts of group IV elements (~3 at.% of Zr, ~7 at.% Hf, and ~10 at.% Ti).

The crystal structures of synthetic K-dravite [XKYMg 3 Z Al 6 T Si6O18(BO3) 3 V (OH) 3 W (OH)], dravite [XNaYMg 3 Z Al 6 T Si6O18(BO3) 3 V (OH) 3 W (OH)], oxy-uvite [XCaYMg 3 Z Al 6 T Si6O18(BO3) 3 V (OH) 3 W O], and magnesio-foitite [X☐Y(Mg2Al)ZAl 6 T Si6O18(BO3) 3 V (OH) 3 W (OH)] are investigated by polarized Raman spectroscopy, single-crystal structure refinement (SREF), and powder X-ray diffraction. The use of compositionally simple tourmalines characterized by electron microprobe analysis facilitates the determination of site occupancy in the SREF and band assignment in the Raman spectra. The synthesized K-dravite, oxy-uvite, and magnesio-foitite have significant Mg–Al disorder between their octahedral sites indicated by their respective average 〈Y–O〉 and 〈Z–O〉 bond lengths. The Y- and Z-site compositions of oxy-uvite (YMg1.52Al1.48(10) and ZAl4.90Mg1.10(15)) and magnesio-foitite (YAl1.62Mg1.38(18) and ZAl4.92Mg1.08(24)) are refined from the electron densities at each site. The Mg–Al ratio of the Y and Z sites is also determined from the relative integrated peak intensities of the Raman bands in the O–H stretching vibrational range (3250–3850 cm−1), producing values in good agreement with the SREF data. The unit cell volume of tourmaline increases from magnesio-foitite (1558.4(3) A3) to dravite (1569.5(4)–1571.7(3) A3) to oxy-uvite (1572.4(2) A3) to K-dravite (1588.1(2) A3), mainly due to lengthening of the crystallographic c-axis. The increase in the size of the X-site coordination polyhedron from dravite (Na) to K-dravite (K) is accommodated locally in the crystal structure, resulting in the shortening of the neighboring O1–H1 bond. In oxy-uvite, Ca2+ is locally associated with a deprotonated W (O1) site, whereas vacant X sites are neighbored by protonated W (O1) sites. Increasing the size of the X-site-occupying ion does not detectably affect bonding between the other sites; however, the higher charge of Ca and the deprotonated W (O1) site in oxy-uvite are correlated to changes in the lattice vibration Raman spectrum (100–1200 cm−1), particularly for bands assigned to the T 6O18 ring. The Raman spectrum of magnesio-foitite shows significant deviations from those of K-dravite, dravite, and oxy-uvite in both the lattice and O–H stretching vibrational ranges (100–1200 and 3250–3850 cm−1, respectively). The vacant X site is correlated with long- and short-range changes in the crystal structure, i.e., deformation of the T 6O18 ring and lengthening of the O1–H1 and O3–H3 bonds. However, X-site vacancies in K-dravite, dravite, and oxy-uvite result only in the lengthening of the neighboring O1–H1 bond and do not result in identifiable changes in the lattice-bonding environment.

The crystal structure of vigrishinite, an epistolite-group heterophyllosilicate with essential Zn, has been reinvestigated, the ideal end-member formula is revised to Zn 2 Ti 4− x (Si 2 O 7 ) 2 O 2 (OH,F,O) 2 (H 2 O,OH,□) 4 with x 4 solution at 90°C have been obtained from single-crystal X-ray diffraction data. The structural formulae are [ B 1] Ca 0.04 {Na 1.22 (Ti 1.19 Mn 0.60 Nb 0.21 )}{ [ A 1, A 2] Zn 1.03 (Ti 1.64 Nb 0.36 )[Si 2 O 7 ] 2 }O 2 (O,OH) 2 (H 2 O) 4 for vigrishinite and {Na 1.14 (Ti 1.45 Mn 0.50 Nb 0.05 )}{ [ A 1] Ca 0.77 [ A 2] Zn 0.13 (Ti 1.85 Nb 0.15 )[Si 2 O 7 ] 2 }O 2 (OH,O) 2 (H 2 O) 4 and [ B 1] Zn 0.15 [ B 2] Ca 0.18 {Na 1.06 (Ti 1.32 Mn 0.60 Nb 0.08 )}{ [ A 1] Zn 0.70 [ A 2] Ca 0.12 (Ti 1.74 Nb 0.26 )[Si 2 O 7 ] 2 }O 2 (OH,O) 2 (H 2 O) 4 for the 5 and 24 hour Zn-exchanged forms of murmanite, respectively (braces give successively the contents of the octahedral O and heteropolyhedral H sheets). The triclinic ( P −1) unit-cell parameters are respectively: a = 8.7127(17), 8.871(3), 8.748(2) A; b = 8.6823(17), 8.844(6), 8.724(2) A; c = 11.746(2), 11.734(6), 11.675(3) A; α = 91.481(4), 92.75(3), 92.503(13)°; β = 98.471(4), 97.60(4), 97.846(13)°; γ = 105.474(4), 106.23(2), 105.875(13)°; V = 845.0(3), 872.7(8), 845.9(4)A 3 . Our data (1) confirm that vigrishinite was formed as a result of natural ion-exchange of murmanite Na 4 Ti 4 (Si 2 O 7 ) 2 O 4 · 4H 2 O with Zn 2+ in low-temperature solutions; (2) prove that direct transformation of lomonosovite Na 4 Ti 4 (Si 2 O 7 ) 2 O 4 · 2Na 3 PO 4 into vigrishinite, without prior leaching of Na + and PO 4 3− from the former and formation of murmanite, is unlikely; (3) suggest the following ion-exchange mechanism: during the early stage Na + leaches into the solution whereas Ca 2+ , a common admixture in murmanite, migrates into one of the sites in the H sheet, leaving another site vacant for further entry of Zn; in the next stage Zn 2+ enters the emptied site in the H sheet and, in small amount, into the interlayer whereas Ca 2+ partly moves from the H sheet into the interlayer. (4) The data show the transformation of the murmanite-type unit cell ( P −1; V ≈ 440 A 3 ) into the vigrishinite-type cell with a and b parameters corresponding to the ab face diagonals of the former during the first stage of the exchange with Zn, due to ordering in the H sheet. New findings of vigrishinite in two pegmatites of the Lovozero massif, Kola peninsula, Russia (at Severnyi open pit, Mt. Alluaiv, and at Pegmatite #60, Mt. Karnasurt) in the same setting as at the type locality, i.e . only in close contact with cavities after dissolved sphalerite, show that the ion exchange in epistolite-group heterophyllosilicates is not uncommon in Nature. Our data indicate there is a continuous solid solution between murmanite and vigrishinite.

The constitution of the binary system Ir-B has been established between 10 and 70 at.% boron for temperatures above 700°C based on differential scanning calorimetry, electron probe microanalysis, and isothermal low temperature annealing experiments (≤1000°C). Four binary phases have been found, namely Ir4B5+x , Ir5B4+x and the high and low temperature modification of Ir4B3-x . X-ray structure analyses were performed on single crystals of Ir4B5+x (x = 0, Ir4B5 type; space group C2/m; a = 1.05200(2), b = 0.289564(6) and c = 0.60958(1) nm, β = 91.156(2)°), Ir5B4+x (x=0, Ir5B4 type; space group I41/a; a = 0.62777(1) and b = 1.02599(2) nm) and on the low temperature modification of Ir4B3-x (x=0, IrB0.9 type; space group Cmc21; a = 0.27728(1), b = 0.75742(2) and c = 0.73152(2) nm). The high temperature modification of Ir4B3-x (WC type; space group $$P\overline 6 m2$$ ; a = 0.28137(5) and c = 0.2828(1) nm) has been confirmed by X-ray powder diffraction. By means of the first-principle calculations, in combination with the evolutionary structural search algorithm, the compositions, structures and enthalpies of the Ir-B system have been investigated theoretically. Confirming the experimental observations on Ir4B5, Ir5B4 and Ir4B3, we have investigated several metastable phases at other stoichiometries, such as IrB, IrB2 and Ir3B2. We also proposed three thermodynamically and dynamically stable new structures of oF28-Ir4B3, oC8-IrB and mC10-Ir3B2, which may be synthesized under certain conditions.

A monoclinic (2 M ) polytype of sideronatrite, Na 2 Fe(SO 4 ) 2 (OH)(H 2 O) 3 , was found at Xitieshan, Qinghai Province, China. The crystal structure was solved by direct methods and refined by full-matrix least-squares ( R 1 = 3.88 %) in the space group P 12 1 / n 1 with a = 7.1559(14), b = 7.2845(15), c = 20.889(4) A, β = 99.37(3)°, V = 1074.4(4) A 3 , and Z = 4, using 2207 observed reflections with I > 2σ( I ). The atomic arrangement of sideronatrite-2 M confirms a theoretical model in space group P 2 1 / a , previously proposed in literature. The structure of sideronatrite-2 M is based on ferric-sulfate chains of 7 A periodicity, similar to those observed in the structures of the orthorhombic polytype and of metasideronatrite. The system of hydrogen bonds has been determined.

Four Mn(NCS)2 based compounds of the types [Mn(SCN)2(L1)]·EtOH (1), [Mn(SCN)2(L2)]·½EtOH (2), [Mn(SCN)2(L3)] (3), and [Mn(SCN)2(L4)2]n·3nMeCN (4) [L1 = benzilbis((pyridin-2-yl)methylidenehydrazone), L2 = benzilbis((acetylpyridin-2-yl)methylidenehydrazone, L3 = benzilbis((phenylpyridin-2-yl)methylidenehydrazone, and L4 = benzilbis((pyridin-3-yl)methylidenehydrazone)] were synthesized and characterized by single-crystal X-ray diffraction studies, elemental analysis, and IR spectroscopy. The first three complexes of general formula Mn(SCN)2(L1–3) consist of discrete units, whereas the fourth one consists of one-dimensional coordination polymer. The central metal atoms in 1–4 exhibit a distorted octahedral arrangement.

Phase equilibria in the isothermal sections of the ternary systems Sr-{Ag, Au}-{Si, Ge} were determined in the (Si) or (Ge) rich part up to 33.3 at % Sr after annealing at 700 °C (Sr-{Ag, Au}-Ge) or 800 °C (Sr-{Ag, Au}-Si). Tentative liquidus projections were constructed for the Si, Ge-rich part of all the four phase diagrams. These systems are characterized by a series of ternary compounds, exhibiting in some cases extended homogeneity regions at a constant Sr content. Compounds in the Si, Ge-rich region essentially form along two sections: at 33.3 at % Sr (AlB2-family) and at 20 at % Sr (BaAl4-family of structure types). The crystal structures of the novel equilibrium phases were derived by X-ray single crystal diffraction: Sr2Ag1+xSi3–x–y□y [Sr2LiSi3 type; x = 0.17, y = 0.43: a = 8.4488(2), b = 14.6376(2), c = 18.4018(2) A], SrAg2–xSi2+x [ThCr2Si2 type; x = 0.1: a = 4.37664(6), c = 10.4517(2) A], Sr(Au1–y□y)(Si1–xAux)3 [BaNiSn3 type; x = 0.59, y = 0.64: a = 4.4594(2), c = 10.1013(6) A] and SrAu5–x□xSi2 [BaAu5Si2 type; x = 0.7: a = 8.7557(3), b = 6.9945(2), c = 9.8873(3) A]. The crystal structures of Sr(AgxGe1–x)2 [AlB2 type; x = 0.25: a = 4.3431(2), c = 4.5938(1) A], SrAg2–xGe2+x [ThCr2Si2 type; x = 0.2: a = 4.4476(2), c = 10.822(1) A] and Sr(AuxGe1–x)2 [AlB2 type; x = 0.25: a = 4.3263(2), c = 4.5852(7) A] were evaluated by X-ray powder Rietveld analysis. Composition dependent polymorphism was observed among the BaAl4-type derivative structures for SrAu2–xGe2+x: CaBe2Ge2 type [x = 0.45: a = 4.4796(2), c = 10.6315(5) A], BaCu2Sb2 type [x = 0.35: a = 4.4866(2), c = 31.808(1) A] and ThCr2Si2 type [x = 0.2: a = 4.5214(4), c = 10.336(1) A]. Similarly, Sr(AuxSi1–x)2 exhibits the Ca2AgSi3 structure type [x = 0.25: a = 8.3407(2), b = 14.4465(2) and c = 9.2664(3) A] and the AlB2 type [x = 0.375: a = 4.2241(2), c = 4.5799(3) A]. The structural chemistry of the BaAl4 derivative structures within the sections SrT2–xX2+x is discussed.

Distinctly chemically zoned tourmaline was found in a quartz vein near Tisovec, Slovak Ore Mountains, Slovakia. The tourmaline forms radial aggregates of light grey to green thin prismatic to acicular crystals growing in cracks in the host rock. The root zone of the aggregates has dravitic to oxy-dravitic compositions, shifting to magnesio-foitite in the middle parts of the crystals and to foititic compositions in the outer parts of the aggregates. The optimized formula, considering the single-crystal structure refinement (SREF) and the chemistry of the magnesio-foititic zone, is ~ X (□ 0.5 Na 0.4 Ca 0.1 ) Y (Mg 1.1 Al 1.0 Fe 2+ 0.8 Fe 3+ 0.1 ) Z (Al 5.7 Fe 3+ 0.3 ) (Si 5.9 Al 0.1 O 18 ) (BO 3 ) 3 (OH) 3 [O 0.6 (OH) 0.3 F 0.1 ], with lattice parameters (SREF) a 15.929(2) A, c 7.163(1) A, and V 1574.0(7) A 3 . SREF data as well as a detailed study of bond lengths indicate a dominancy of Al 3+ at the Z site substituted by a small proportion of Fe 3+ , while Fe 2+ and Mg 2+ essentially occupy the Y site along with a significant amount of Al. The chemical composition is controlled by the substitutions FeMg –1 , Al□(Fe,Mg) –1 Na –1 , and AlO(Fe,Mg) –1 (OH) –1 . The AlO(Fe,Mg) –1 (OH) –1 substitution is dominant in the transition from oxy-dravite to magnesio-foitite, and the Al□(Fe,Mg) –1 Na –1 substitution prevails in the magnesio-foitite and foitite compositions. Both proton- and alkali-deficient substitutions produce the enrichment in Al which can be linked to the forming of the acicular habit. Aluminum strongly prefers the Z -site, whose octahedra form a network of chains parallel to c . Consequently, polymerization of the Z O 6 octahedral network will dominate growth in the a direction. Therefore, the chemical composition, mainly Al enrichment, which is common for most of the acicular to fibrous tourmalines, can be an important factor promoting preferential growth in the c direction. The rate and time for crystallization, which depend mostly on the temperature and cooling rate, are also factors which should be considered.

Phase equilibria of the system Ti–Ni–Sn have been determined for the isothermal section at 950 °C based on X-ray powder diffraction (XPD) and electron probe microanalysis (EPMA) of about 60 ternary alloys in as cast and annealed state. The section is characterized by the formation of four ternary compounds labelled τ1 to τ4. Whereas two of the ternary compounds are found without significant homogeneity regions: τ1-TiNiSn (half Heusler phase, MgAgAs-type), τ3-Ti2Ni2Sn (U2Pt2Sn-type), τ4-(Ti1−x−ySnxNiy)Ni3 with AuCu3-type exhibits a solution range (0.22 ≤ x ≤ 0.66 and 0.22 ≥ y ≥ 0.02) and a particularly large homogeneity region is recorded for τ2-Ti1+yNi2−xSn1−y (Heusler phase, MnCu2Al-type). Extended solid solutions starting from binary phases at 950 °C have been evaluated for Ti5Ni1−xSn3 (filled Mn5Si3 = Ti5Ga4-type; 0 ≤ x ≤ 1), Ti1−xSnxNi3 (TiNi3-type; 0 ≤ x ≤ 0.27) and (Ti1−xNix)1−ySny (CsCl-type) reaching a maximum solubility at x = 0.53, y = 0.06). From differential thermal analysis (DTA) in alumina crucibles under argon a complete liquidus surface has been elucidated revealing congruent melting for τ2-TiNi2Sn at 1447 °C, but incongruent melting for τ1-TiNiSn (pseudobinary peritectic formation: + τ2 ↔ τ1 at 1180 °C), τ3-Ti2Ni2Sn (peritectic formation: L + τ2 + Ti5NiSn3 ↔ τ3 at 1151 °C) and τ4-Ti1−xSnxNi3 (peritectic formation: L + TiNi3 + (Ni) ↔ τ4 at 1157 °C). A Schultz–Scheil diagram for the solidification behavior was constructed for the entire diagram involving 20 isothermal four-phase reactions in the ternary. For a thermodynamic CALPHAD assessment of the ternary diagram we relied on the binary boundary systems as modelled in the literature. As thermodynamic data in the ternary system were only available in the literature for the compounds TiNi2Sn and TiNiSn, heat of formation data were supplied by our density functional theory (DFT) calculations for Ti2Ni2Sn, as well as for the solid solutions, which were modelled for Ti1−xSnxNi3, Ti5Ni1−xSn3 and (Ti1−xNix)1−ySny. Thermodynamic calculation was performed with the Pandat software and finally showed a reasonably good agreement for all the 20 invariant reaction isotherms involving the liquid.

The novel compounds Ba5{V,Nb}12Sb19+x, initially found in diffusion zone experiments between Ba-filled skutterudite Ba0.3Co4Sb12 and group V transition metals (V,Nb,Ta), were synthesized via solid state reaction and were characterized by means of X-ray (single crystal and powder) diffraction, electron probe microanalysis (EPMA), and physical (transport and mechanical) properties measurements. Ba5V12Sb19.41 (a = 1.21230(1) nm, space group P4[combining overline]3m; RF(2) = 0.0189) and Ba5Nb12Sb19.14 (a = 1.24979(2) nm, space group P4[combining overline]3m; RF(2) = 0.0219) are the first representatives of the Ba5Ti12Sb19+x-type, however, in contrast to the aristotype, the structure of Ba5V12Sb19.41 shows additional atom disorder. Temperature dependent ADPs and specific heat of Ba5V12Sb19.41 confirmed the rattling behaviour of Ba1,2 and Sb7 atoms within the framework built by V and Sb atoms. Electrical resistivity of both compounds show an upturn at low temperature, and a change from p- to n-type conductivity above 300 K in Ba4.9Nb12Sb19.4. As expected from the complex crystal structure and the presence of defects and disorder, the thermal conductivity is suppressed and lattice thermal conductivity of ∼0.43 W m(-1) K(-1) is near values typical for amorphous systems. Vicker's hardness of (3.8 ± 0.1) GPa (vanadium compound) and (3.5 ± 0.2) GPa (niobium compound) are comparable to Sb-based filled skutterudites. However, the Young's moduli measured by nanoindentation for these compounds EI(Ba4.9V12Sb19.0) = (85 ± 2) GPa and EI(Ba4.9Nb12Sb19.4) = (79 ± 5) GPa are significantly smaller than those of skutterudites, which range from about 130 to 145 GPa.

In the reaction of 1,3-dimethyl-pyrazole-5-carboxylic acid (HL) with M(OAc)2•4H2O, (M = Cu, Co) two novel complexes have been prepared, square-planar [CuL2(H2O)2] and octahedral [CoL2(MeOH)4]. The crystal structures have been determined by single-crystal X-ray diffraction. In both complexes the deprotonated acid displays monodentate coordination to the metal ions. According to the results of CSD survey this is the first structural report on the metal complexes with N1-substituted pyrazole-5-carboxylic ligand. [Projekat Ministarstva nauke Republike Srbije, br. 172014 i br. 172035]

1-(3-Halopropyl)-1H-tetrazoles and their corresponding Fe

In the ternary system Sr-Cu-Ge, a clathrate type-I phase, Sr8Cu5.3Ge40.7 (a = 1.06311(3), exists close to the Zintl limit in a small temperature interval. Sr8Cu5.3Ge40.7 decomposes eutectoidally on cooling at 730��C into (Ge), SrGe2 and tau1-SrCu2-xGe2+x. Phase equilibria at 700��C have been established for the Ge rich part and are characterized by the appearance of only one ternary compound, tau1-SrCu2-xGe2+x, which crystallizes with the ThCr2Si2 structure type and forms a homogeneity range up to x=0.4 (a = 0.42850(4), c = 1.0370(1) nm). Additionally, the extent of the clathrate type-I solid solution Ba8-xSrxCuyGe46-y (5.2 < y < 5.4) has been studied at various temperatures. The clathrate type-I crystal structure (space group ) has been proven by X-ray single crystal diffraction on two single crystals with composition Sr8Cu5.3Ge40.7 (a = 1.06368(2) nm) and Ba4.9Sr3.1Cu5.3Ge40.7 (a = 1.06748(2) nm) measured at 300, 200 and 100 K. From the temperature dependency of the lattice parameters and the atomic displacement parameters, the thermal expansion coefficients, the Debye- and Einstein-temperatures and the speed of sound have been determined. From heat capacity measurements of Sr8Cu5.3Ge40.7 at low temperatures, the Sommerfeld coefficient and the Debye temperature have been extracted, whereas from a detailed analysis of these data at higher temperatures, Einstein branches of the phonon dispersion relation have been derived and compared with those obtained from the atomic displacement parameters. Electrical resistivity measurements of Sr8Cu5.3Ge40.7 reveal a rather metallic behaviour in the low temperature range (< 300 K)., 22 pages, 7 figures

Ba2Ho10(Si2O7)3(Si3O10)2 and isotypic Ba2Er10(Si2O7)3(Si3O10)2 represent a new mixed-framework structure type with an unprecedented ratio of di- and trisilicate groups among silicates. The atomic arrangement features asymmetric zigzag chains of edge-sharing Ln3+O6 (Ln = Ho, Er) octahedra corner-linked by isolated Si2O7 and horseshoe-shaped Si3O10 groups in the ratio of 3:2. Single-crystal X-ray diffraction investigations yielded the triclinic space group P 1 ¯ (no. 2), with a = 5.5494(11)/5.5360(11) A, b = 6.8795(14)/6.6870(13) A, c = 23.703(5)/23.691(5) A, α = 83.60(3)/83.64(3)°, β = 88.80(3)/88.77(3)°, γ = 73.43(3)/73.38(3)°,V = 861.9(3)/835.2(3) A3, R(F) = 0.0289/0.0559, respectively. The laser-induced photoluminescence emission of trivalent holmium und erbium in both framework silicates was studied using a dispersive single-stage spectrometer and compared to the emission spectra of other framework Ba-Er and Ba-Ho silicates. The 4S3/2→4I15/2 transition of Er in Ba2Er10(Si2O7)3(Si3O10)2 causes a photoluminescence emission in the visible green spectral range whereas its Ho representative with the 5F3→5I7 transition in the red spectral region.

C13H10F3N3O4, triclinic, P1̅ (no. 2), a = 7.0524(14) Å, b = 7.8044(16) Å, c = 12.954(3) Å, α = 97.93(3)°, β = 96.29(3)°, γ = 100.11(3)°, V = 688.6(3) Å3, Z = 2, R gt(F) = 0.0478, wR ref(F 2) = 0.1140, T = 200 K.

New nickel(II) and copper(II) coordination compounds were synthesized by the reaction of N-(benzyloxycarbonyl)-1H-pyrazole-1-carboxamidine ligand (HL) with Ni(II) and Cu(II) acetate in methanolic solution. The crystal and molecular structures of the complexes as well as those of the ligand were determined by single-crystal X-ray structure analysis. The octahedral surrounding around the metal centers in the isostructural complexes [ML2(MeOH)(2)], M = Ni(II), Cu(II), MeOH = methanol, is established by the bidentate coordination of two ligand molecules through the pyrazole nitrogen and the deprotonated nitrogen atom of the carboxamidine group along with the oxygen atoms from two MeOH molecules. Despite that the molecular structure of the complexes was determined by X-ray structure analysis, in the FT-IR spectra of the compounds the characteristic bands for MeOH were missing. By coupled TG-MS measurements, it was found that compounds during the transport and storage exchanged MeOH by water molecules. The amount of the water was calculated on the basis of thermogravimetric data. The antifungal activity of the compounds was tested against fungi Ph. viticola and B. dothidea and compared to that of a commercial fungicide. Depending on the fungi and on the structure, the compounds showed different, but somewhat lower activity than the commercial fungicide.

Na-K interdiffusion in disordered potassium-rich alkali feldspar was studied experimentally using cation exchange between gem quality sanidine from the Eifel and alkali-halide melt at temperatures of 800 °C to 1000 °C and at close to ambient pressure. Sodium-potassium interdiffusion coefficient DNaK was determined for potassium mole fractions in the range 0.65 ≤ XOr ≤ 0.99. At 0.65 ≤ XOr ≤ 0.95 the sodium-potassium interdiffusion coefficient is largely independent of composition. At XOr ≥ 0.95, it rises sharply with increasing potassium mole fraction. Diffusion perpendicular to (001) is about one order of magnitude faster and less strongly temperature dependent than perpendicular to (010). The parameters of the Arrhenius equation describing the temperature dependence of the sodium-potassium interdiffusion coefficient DNaK = D0Exp (−EA/RT) were estimated as The results of our direct determinations are compared with theoretical calculations using the corresponding sodium- and potassium tracer-diffusion coefficients, and the processes underlying the observed composition- and temperature dependence of sodium-potassium interdiffusion are discussed.

Polarized electronic absorption spectra of colourless chalcocyanite, CuSO4, have been measured using microscope-spectrometric techniques. The spectra are characterized by a structured and clearly polarized band system in the near-infrared spectral range with components centred at 11,720, 10,545, 9,100, and 7,320 cm−1, which have been assigned to crystal field d–d transitions of Cu2+ cations in pseudo-tetragonally elongated CuO6 polyhedra with point symmetry C i ( $$\bar{1}$$ ). The polarization behaviour is interpreted based on a D 2(C 2″) pseudo-symmetry. Crystal field calculations were performed for the actual triclinic point symmetry by applying the Superposition Model of crystal fields, as well as in terms of a ‘classic’ pseudo-tetragonal crystal field approach yielding the parameters Dq (eq) = 910, Dt = 395, and Ds = 1,336 cm−1, corresponding to a cubically averaged Dq cub = 679 cm−1. A comparative survey on crystal fields in Cu2+ minerals shows that the low overall crystal field strength in chalcocyanite, combined with a comparatively weak pseudo-tetragonal splitting of energy levels, is responsible for its unique colourless appearance among oxygen-based Cu2+ minerals. The weak crystal field in CuSO4 can be related to the lower position of the SO4 2− anion compared to, e.g. the H2O molecule in the spectrochemical series of ligands.

The crystal structure of W1−x B3 has been reinvestigated by x-ray single crystal diffraction and revealed isotypism with the Mo1−x B3 structure type (space group P63/mmc; a = 0.52012(1), c = 0.63315(3) nm; R F = 0.040). As a characteristic feature of the structure, planar hexagonal metal layers (1/3 of atoms removed from ordered positions) sandwich planar boron honeycomb layers. One of the two W-sites shows a random defect of about 73%. Strong metal boron and boron-boron bonds are responsible for high mechanical stability. Although W1−x B3 at about 80 at.% B is the metal boride richest in boron, it contains no directly linked three-dimensional boron framework. The solubility of Rh, Ir, Ni, Pd and Pt in W1−x B3 as well as of Rh in Mo1−x B3 has been investigated in as cast state and after annealing. Furthermore, phase equilibria in the boron rich part of the corresponding isothermal sections W-TM-B (TM = Rh, Ir at 1100 °C, TM = Ni, Pd at 900 °C and TM = Pt at 800 °C) and Mo-Rh-B (at 1100 °C) have been established. A ternary compound only forms in the system W-Ir-B: τ1-W1−x Ir x B2 with ReB2 structure type (space group P63/mmc; a = 0.2900, c = 0.7475 nm). The type of formation and crystal structure of diborides W1−x TM x B2 (TM = Ru, Os, Ir) isotypic with ReB2 were studied by x-ray powder diffraction and electron probe microanalysis in as cast state and after annealing at 1500 °C. Accordingly, W0.5Os0.5B2 (a = 0.29127(1), c = 0.7562(1) nm) forms directly from the melt, whereas W0.4Ru0.6B2 (a = 0.29027(1), c = 0.74673(2) nm) and W0.6Ir0.4B2 (a = 0.29263(1), c = 0.75404(8) nm) are incongruently melting. Annealing at 1500 °C leads in case of the iridium compound to an almost single-phase product but the same procedure does not increase the amount of the ruthenium diboride.

Putnisite, SrCa4Cr83+ (CO7)8SO4(OH)16·25H2O, is a new mineral from the Polar Bear peninsula, Southern Lake Cowan, Western Australia, Australia. The mineral forms isolated pseudocubic crystals up to 0.5 mm in size in a matrix composed of quartz and a near amorphous Cr silicate. Putnisite is translucent, with a pink streak and vitreous lustre. It is brittle and shows one excellent and two good cleavages parallel to {100}, {010} and {001}. The fracture is uneven and the Mohs hardness 1½−2. The measured density is 2.20(3) g/cm3 and the calculated density based on the empirical formula is 2.23 g/cm3. Optically, putnisite is biaxial negative, with α = 1.552(3), β = 1.583(3) and γ = 1.599(3) (measured in white light). The optical orientation is uncertain and pleochroism is distinct: X pale bluish grey, Y pale purple, Z pale purple. Putnisite is orthorhombic, space group Pnma, with a = 15.351(3), b = 20.421(4) Å, c = 18.270(4) Å, V = 5727(2) Å3 (single-crystal data), and Z = 4. The strongest five lines in the X-ray powder diffraction pattern are [d(Å)(I)(hkl)]: 13.577 (100) (011), 7.659 (80) (200), 6.667 (43) (211), 5.084 (19) (222, 230), 3.689 (16) (411). Electron microprobe analysis (EMPA) gave (wt.%): Na2O 0.17, MgO 0.08, CaO 10.81, SrO 5.72, BaO 0.12, CuO 0.29, Cr2O3 31.13, SO3 3.95, SiO2 0.08, Cl− 0.28, CO2calc 17.94, H2Ocalc 30.30, O=Cl−0.06, total 100.81. The empirical formula, based on O + Cl = 69, is: Cr8.023+Ca3.78Sr1.08Na0.11Cu0.072+Mg0.04Ba0.02[(SO4)0.96(SiO4)0.03]0.99 (CO3)7.98(OH)16.19Cl0.15·24.84H2O. The crystal structure was determined from single-crystal X-ray diffraction data (MoKα, CCD area detector and refined to R1 = 5.84% for 3181 reflections with F0 > 4σF. Cr(OH)4O2 octahedra link by edge-sharing to form an eight-membered ring. A 10-coordinated Sr2+ cation lies at the centre of each ring. The rings are decorated by CO3 triangles, each of which links by corner-sharing to two Cr(OH)4O2 octahedra. Rings are linked by Ca(H2O)4O4 polyhedra to form a sheet parallel to (100). Adjacent sheets are joined along [100] by corner-sharing SO4 tetrahedra. H2O molecules occupy channels that run along [100] and interstices between slabs. Moderate to weak hydrogen bonding provides additional linkage between slabs.

Constitution of the ternary systems Nb-Co-B and Ta-Co-B was studied, employing optical and electron microscopy, x-ray powder, single crystal diffraction, electron probe microanalysis, DTA and Pirani melting point measurements. Ternary phase equilibria were determined within an isothermal section at 1100 °C. For the Co-rich part (≥50 at.% Co) of the system, a liquidus surface projection and a corresponding Schulz-Scheil reaction scheme were constructed in combination with data for primary crystallization from as-cast samples determined by SEM and EPMA measurements. The crystal structures of novel ternary compounds have been elucidated by x-ray powder and single crystal diffraction and were supported by TEM. {Nb,Ta}CoB with NbCoB-type exhibits a high temperature modification (ZrAlNi-type, a = 0.5953 nm, c = 0.3248 nm; a = 0.5926 nm, c = 0.3247 nm for Nb and Ta respectively), which was only present in as-cast alloys, but found to be stabilized by the addition of Fe to annealing temperatures of 1400 °C. Ta3Co4B7 (a = 0.3189 nm, b = 1.8333 nm, c = 0.8881 nm) was proven to be isotypic with Nb3Co4B7. The novel orthorhombic compounds {Nb,Ta}Co2B3 (TaCo2B3-type with space group Pnma; a = 0.53628 nm, b = 0.32408 nm, c = 1.24121 nm for TaCo2B3; a = 0.53713 nm, b = 0.32442 nm, c = 1.2415 nm for NbCo2B3) adopt unique structure types with branched boron zig-zag chains. {Nb,Ta}Co2B were found to crystallize in a unique monoclinic structure type (space group P21/c; a = 0.9190 nm, b = 0.64263 nm, c = 0.63144 nm; β = 109.954°, for Nb) very close to an orthorhombic setting (Cmce, a = 0.63162 nm, b = 1.72810 nm, c = 0.64270 nm, for Nb). Substitution of Co by Ni stabilizes a smaller orthorhombic lattice with Re3B-type structure (Cmcm) although no homologue compound in the Ni-system exists. The crystallographic relations among the structure types of Re3B and pseudo-orthorhombic as well as monoclinic {Nb,Ta}Co2B were defined in terms of a Barnighausen scheme. DFT calculations revealed very close stabilities for the three competing structure types for {Nb,Ta}Co2B. Detailed transmission electron microscopy (TEM) for Nb(Co,Fe)B, {Nb,Ta}Co2B, {Nb,Ta}(Co,Ni)2B, and Ta3Co4B7 confirmed lattice geometries and crystal symmetry. Vickers hardness was measured for {Nb,Ta}Co2B, {Nb,Ta}(Co,Ni)2B, {Nb,Ta}2−xCo21+xB6 and {Nb,Ta}Co2B3 exhibiting the highest value of hardness of HV = 22.4 ± 1.1 GPa for TaCo2B3. Magnetic, specific heat and electrical resistivity measurements on the compounds TaCo2B and Ta2Co21B6 reveal paramagnetic and ferromagnetic metallic ground states, respectively.

International audience; Phase relations in the Th-Pd-B system were determined via electron microprobe and X-ray powder diffraction analyses of similar to 20 ternary alloys. Phase equilibria are dominated by the two high-melting thorium borides ThB4, Th1-yB6 and one ternary compound, namely tau(1)-Th2Pd14+xB5, with a structure deriving from the Sc4Ni29B10-type. Th1-yB6 is the binary starting point of a continuous solid solution up to ThPd0.53B4.28 closely corresponding to the superconducting phase Th1-yPdxB6-2x (x

The crystal structure of the novel intermetallic Yb ∼3 Pt ∼4 Si 6− x was determined by single crystal X-ray diffraction: space group P 2 1 / m (No. 11); a = 8.4560(3) A, b = 4.2109(2) A, c = 12.7864(5) A, β = 99.537(2)°, R F = 0.046, wR2 = 0.132. The title compound is a disordered variant of the Y 3 Pt 4 Ge 6 type. It is characterized by the intergrowth of slabs cut from the ThCr 2 Si 2 and YIrGe 2 types of structures.

Phase relations were investigated for the In-Co-Sb system in the temperature range from 375°C to 800°C using as-cast and annealed alloys. Phase equilibria in the CoSb-InSb-(Sb) composition triangle are presented by a series of isothermal sections and solidus and liquidus surfaces, accompanied by a Schulz–Scheil reaction scheme. The indium-filled skutterudite InyCo4Sb12 already forms an equilibrium with liquid at 484°C, which might limit high-temperature applications of In-Co-Sb-based skutterudites. The maximal solubility of indium in InyCo4Sb12 (y = 0.22) remains almost constant in the temperature range from 475°C to 700°C and corresponds to the equilibrium with CoSb2 and InSb. The solubility of indium in the skutterudite phase is reduced to y = 0.09 when it coexists in equilibrium with InSb and (Sb), and this decrease of the solubility might be responsible for the formation of InSb precipitates. Temperature-dependent x-ray single-crystal and specific heat data for InyCo4Sb12 were employed to determine the rattling behavior of In atoms in the skutterudite lattice.

The crystal structure of beta-rhombohedral boron co-doped with nickel and zinc was refined using a single crystal of the composition Ni44.4Zn11.2B44.4 (in at.%) (space group, R 3 ¯ m , a = 1.10182(2) nm, c = 2.40534(5) nm, RF = 0.040, residual electron density

A trisilicate with a new structure type, CoEu2Si3O10, was obtained from molybdate–carbonate mixtures in Pt crucibles by using a high-temperature flux-growth method. The structural characterization of CoEu2Si3O10 was done by evaluation of single-crystal X-ray diffraction data collected at three different temperatures (105, 293, and 370 K). The light violet crystals are monoclinic, space group P21/n with a = 6.5620(13), b = 6.7207(13), c = 16.986(3) A, β = 90.06(3)°, V = 749.1(3) A3, and R(F) = 2.49 %, at room temperature. The new crystal structure type features layers parallel to (001) containing Si3O10 groups and Co2O10 dimers. The Si–Si–Si angle of the Si3O10 unit is 115.7°. Raman spectroscopy and a study of the photoluminescence properties of the Eu3+ ions in CoEu2Si3O10 were undertaken.

Phase relations in the {Si,Ge}-rich part of the three systems Ba–Ir–Ge and Ba–{Rh,Ir}–Si were investigated by means of X-ray single crystal (SC) and powder diffraction (XPD), EPMA and DTA measurements. For Ba–Ir–Ge, partial isothermal sections were constructed at 800 °C and 700 °C. The clathrate solid solution extends from binary Ba8Ge43□3 to Ba8Ir0.4Ge43□2.6 with a slightly enlarged lattice parameter a = 2.13402(2) nm ( I a 3 ¯ d , Ba8Ge43□3-type). Two new ternary stoichiometric compounds were found and their crystal structures were determined by X-ray diffraction: τ1-BaIr2Ge7 (Pmna, own type, a = 3.7782(1), b = 0.64099(2), c = 0.64401(2) nm; RF = 0.0331, SC-data) and τ2-Ba3Ir4Ge16 (P4/mmm, Ba3Rh4Ge16-type, a = 0.653948(6), c = 2.22849(3) nm; RF = 0.0388, XPD-Rietveld analysis). The isothermal sections of the Ba–{Rh,Ir}–Si systems were investigated at 950 °C. Whereas in the Ba–Rh–Si system a clathrate-type I solid solution κI-Ba8RhxSi46−x extends within 2.6 ≤ x ≤ 2.9, the corresponding clathrate-I phase in the Ba–Ir–Si system, κI-Ba8Ir1.8Si44.2 ( P m 3 ¯ n , Na4Si23-type, a = 1.0346(1) nm), is not stable at this temperature, but was clearly observed in the as cast state. The analysis of temperature dependent atomic displacement parameters (100–300 K) of guest and framework atoms for κI-Ba8IrxGe46−x−y□y revealed Debye (θD) and Einstein (θE) temperatures of θD = 244 K, θE,11 = 85 K, and θE,22,33 = 64 K proving the rattling nature of the Ba-atoms in the large Ge-based tetrakaidecahedral cages. A similar analysis for κI-Ba8RhxSi46−x yields significantly higher Debye and Einstein temperatures, θD = 508 K, θE,11 = 115 K, θE,22,33 = 99 K, i.e. a tight bonding of Ba-atoms to the smaller Si-based cages. This behavior is further reflected by the pronounced difference in the thermal expansion coefficients: α100–300 K = 13.7 × 10−6 K−1 (κI-Ba8IrxGe46−x−y□y) and α100–300 K = 7.3 × 10−6 K−1 (κI-Ba8RhxSi46−x).

Accurate thermochronologic interpretation of zircon (U-Th)/He dates requires a realistic and practically useful understanding of He diffusion kinetics in natural zircon, ideally across the range of variation that characterize typically dated specimens. Here we present a series of date and diffusion measurements that document the importance of alpha dose, which we interpret to be correlated with accumulated radiation damage, on He diffusivity. This effect is manifest in both date-effective uranium (eU) correlations among zircon grains from single hand samples and in diffusion experiments on pairs of crystallographically oriented slabs of zircon with alpha doses ranging from ∼1016 to 1019 α/g. We interpret these results as due to two contrasting effects of radiation damage in zircon, both of which have much larger effects on He diffusivity and thermal sensitivity of the zircon (U-Th)/He system than crystallographic anisotropy. Between 1.2 × 1016 α/g and 1.4 × 1018 α/g, the frequency factor, D0, measured in the c-axis parallel direction decreases by roughly four orders of magnitude, causing He diffusivity to decrease dramatically (for example by three orders of magnitude at temperatures between 140 and 220 °C). Above ∼2 × 1018 α/g, however, activation energy decreases by a factor of roughly two, and diffusivity increases by about nine orders of magnitude by 8.2 × 1018 α/g. We interpret these two trends with a model that describes the increasing tortuosity of diffusion pathways with progressive damage accumulation, which in turn causes decreases in He diffusivity at low damage. At high damage, increasing diffusivity results from damage zone interconnection and consequential shrinking of the effective diffusion domain size. Our model predicts that the bulk zircon (U-Th)/He closure temperature (Tc) increases from about 140 to 220 °C between alpha doses of 1016 to 1018 α/g, followed by a dramatic decrease in Tc above this dose. Linking this parameterization to one describing damage annealing as a function of time and temperature, we can model the coevolution of damage, He diffusivity, and (U-Th)/He date of zircon. This model generates positive or negative date-eU correlations depending on the extent of damage in each grain and the date-eU sample9s time-temperature history.

Phase relations for the system Ni–Zn–B have been established in the isothermal section at 800 °C based on X-ray powder diffraction and electron microprobe analyses of about 60 samples, which have been prepared by hot pressing of pre-annealed powder compacts of arc-melted master alloys NixBy and Zn-filings. Six ternary compounds (labeled τ1 to τ6) were found to exist, which in some cases exhibit considerable mutual solid solubilities mostly as an exchange of Ni–Zn at constant B-content, but in the case of the so-called τ-phase τ1-(Ni1−xZnx)21[Zn1−y−z□y(B4)z]2B6 (0.07≤x≤0.11, 0.07≤y≤0.53, 0≤z≤0.3) also with Zn/B substitution. Single crystal X-ray data analysis for the composition x=0.07, y=0.125, z=0.30, and a=1.05800(3) nm confirmed the Cr23C6 type with space group F m 3 ¯ m , but revealed partial replacement of Zn-atoms by B4-tetrahedra (RF=0.014). Whereas Ni/Zn exchange (at constant B-content) ranges at about 4–5 at% for τ4-Ni3ZnB2 and τ5-Ni48Zn32B20, it is below 3 at% for τ2-Ni12ZnB8−x (x=0.43), τ3-Ni21Zn2B20 and τ6-Ni47Zn23B30. The crystal structures of τ2-Ni12ZnB8−x (x=0.43; Ni12AlB8 type), τ3-Ni21Zn2B20 (own type) and τ4-Ni3ZnB2 (own type) have been determined in our foregoing paper [8] . Due to the non-availability of suitable single crystals, the crystal structures of τ5-Ni48Zn32B20 (body-centered orthorhombic; a=1.6(2) nm, b=0.63(7) nm, and c=0.27(0) nm, determined from TEM) and of τ6-Ni47Zn23B30 have not been elucidated yet. Phase equilibria at 800 °C are dominated by a large three-phase field (βB)+Ni2Zn11+τ3, as practically all ternary compounds form at compositions with less than about 50 at% Ni. Furthermore, precise data on atom site distribution and positional parameters have been provided from X-ray single crystal refinements for Ni-borides, for which crystal structures hitherto have only been derived from X-ray diffraction photographs: o-Ni4B3−x (x=0.19; Pnma, a=1.9665(4) nm, b=0.29852(1) nm, c=0.65750(2) nm; RF=0.015) and m-Ni4B3 (C2/c, a=0.64356(3) nm, b=0.48867(3) nm, c=0.78267(3) nm, β=103.288(3)°, RF=0.021).

The crystal structure of the rare secondary mineral cualstibite-1M (formerly cyanophyllite), originally reported to have the chemical formula 10CuO·2Al2O3·3Sb2O3·25H2O and orthorhombic symmetry, was solved from single-crystal intensity data (Mo-Kα X-radiation, CCD area detector, 293 K, 2θmax = 80) collected on a twinned crystal containing very minor Mg. The mineral is monoclinic, P21/c (no. 14), with a = 9.938(1), b = 8.890(1), c = 5.493(1) A, β = 102.90(1)°, V = 473.05(11) A3; R1(F) = 0.0326. All crystals investigated turned out to be non-merohedric twins. The atomic arrangement has a distinctly layered character. Brucite-like sheets composed of two [4 + 2]-coordinated (Cu,Al,Mg) sites are linked by weak hydrogen-bonding (O···O ~ 2.80 A) to isolated regular Sb(OH)6 octahedra ( = 1.975 A). The layered, pseudotrigonal character explains the perfect cleavage and the proneness to twinning. The Sb site is fully occupied and the two (Cu,Al,Mg) sites have occupancies of Cu0.79Al0.17Mg0.04 and Cu0.72Al0.23Mg0.05. The Cu-richer site shows a slightly stronger Jahn-Teller-distortion. The resulting empirical formula, which necessitates a H2O-for-OH substitution to obtain charge balance, is (Cu2.23Al0.63Mg0.14)(OH)5.63(H2O)0.37[Sb5+(OH)6]. The ideal chemical formula is (Cu,Al)3(OH)6[Sb5+(OH)6], with Cu:Al = 2:1. The structure is closely related to those of trigonal cualstibite-1T [Cu2AlSb(OH)12, P-3, with ordered Cu-Al distribution in the brucite sheets], and its Zn analogue zincalstibite-1T [Zn2AlSb(OH)12]. Cualstibite-1M and cualstibite-1T are polytypes and, together with zincalstibite-1T, zincalstibite-9R and omsite, belong to the cualstibite group within the hydrotalcite supergroup, which comprises all natural members of the large family of layered double hydroxides (LDH).

Voltaite is a mineral of fumaroles, solfatares, coal-fire gas vents, and acid-mine drainage systems. The nominal composition is K2Fe5 2+Fe3 3+Al(SO4)12·18H2O and the nominal symmetry is cubic, $$Fd\overline{3}c$$ . The tetragonal (I41/acd) superstructure of voltaite is known as the mineral pertlikite. In this study, we investigated 22 synthetic voltaite samples in which Fe2+ was partially or completely replaced by Mg, Zn, Mn, or Cd, by single-crystal and powder X-ray diffraction (both in-house and synchrotron). Two samples contained NH4 + instead of K+. The structure of voltaite is based on a framework defined by krohnkite-like heteropolyhedral chains which host both M3+ and M2+ in octahedral coordination. Unit cell dimensions of the end-members scale almost linearly with the size of M2+. In the Fe2+-Mg-Zn solid solutions, the Fe2+-Mg and Fe2+-Zn solutions are linear (ideal) in terms of their lattice-parameter variations. The Mg-Zn solid solution, however, is strongly non-ideal. A detailed analysis of the topology of the chains showed that this behavior originates in expansion and contraction of individual M2+-O bonds within the chains. In the Mg-Zn solid solution, some of the M2+-O bonds expand while none contract. In the other solid solutions, expansion of some M2+-O bonds is always compensated by contraction of the other ones. Parts of the nominally cubic crystals are optically anisotropic and their symmetry is found to be tetragonal by single crystal X-ray diffraction measurements. The coexistence of cubic and tetragonal sectors within a single crystal without any detectable difference in their chemical composition is difficult to explain in terms of growth of such composite crystals. Mossbauer and infrared spectra collected on our synthetic crystals conform with previously published data.

As the Ti-Mn phase diagram is part of numerous ternary and higher order systems of technological importance, the present paper defines phase relations which have been experimentally established throughout this work from 800 °C to the melting range based on Differential Thermal Analyses (DTA), X-ray powder diffraction, metallography and Electron Probe Micro Analysis (EPMA) techniques on ∼50 alloys, which were prepared by arc melting or high frequency melting under high purity argon starting from freshly cleaned metal ingots. Novel compounds were identified and reaction isotherms were redefined accordingly. In the Ti-rich region a novel compound TiMn was detected, sandwiched between the known phases: TiMn1-x (∼45 at% Mn) and TiMn1+x (∼55 at% Mn). In the Mn-rich region the hitherto unknown crystal structure of TiMn∼3 was solved from X-ray single crystal diffraction data and found to be of a unique structure type Ti6(Ti1-xMnx)6Mn25 (x = 0.462; space group Pbam (#55); a = 0.79081(3) nm, b = 2.58557(9) nm, c = 0.47931(2) nm), which consists of two consecutive layers of the hexagonal MgZn2-type Laves phase (TiMn2) and a combined layer of alternate structure blocks of MgZn2 type and Zr4Al3 type. Whereas TiMn can be considered as a line compound (solubility range

Single crystals of Ce3Pt4Sn6 (I) and Ce1-xPt6Al13+2x (x = 0.207, (II)) are isolated by mechanical fragmentation of specimens grown from self-fluxes (Sn or Al, resp.) by slow cooling from the melt.

Phase relations and crystal structures have been evaluated within the sections LaNi2Si2-LaZn2Si2 and CeNi2Si2-CeZn2Si2 at 800 °C using electron microprobe analysis and X-ray powder and single crystal structure analyses. Although the systems La-Zn-Si and Ce-Zn-Si at 800 °C do not reveal compounds such as "LaZn2Si2" or "CeZn2Si2", solid solutions {La,Ce}(Ni1-xZnx)2Si2 exist with the Ni/Zn substitution starting from {La,Ce}Ni2Si2 (ThCr2Si2-type; I4/mmm) up to x = 0.18 for Ce(Ni1-xZnx)2Si2 and x = 0.125 for La(Ni1-xZnx)2Si2. For higher Zn-contents 0.25 ≤ x ≤ 0.55 the solutions adopt the CaBe2Ge2-type (P4/nmm). The investigations are backed by single crystal X-ray diffraction data for Ce(Ni0.61Zn0.39)2Si2 (P4/nmm; a = 0.41022(1) nm, c = 0.98146(4) nm; RF = 0.012) and by Rietveld refinement for La(Ni0.56Zn0.44)2Si2 (P4/nmm; a = 0.41680(6) nm, c = 0.99364(4) nm; RF = 0.043). Interestingly, the Ce-Zn-Si system contains a ternary phase CeZn2(Si1-xZnx)2 of the ThCr2Si2 structure type (0.25 ≤ x ≤ 0.30 at 600 °C), which forms peritectically at T = 695 °C but does not include the composition "CeZn2Si2". The primitive high temperature tetragonal phase with the CaBe2Ge2-type has also been observed for the first time in the Ce-Ni-Si system at CeNi2+xSi2-x, x = 0.33 (single crystal data, P4/nmm; a = 0.40150(2) nm, c = 0.95210(2) nm; RF = 0.0163). Physical properties (from 400 mK to 300 K) including specific heat, electrical resistivity and magnetic susceptibility have been elucidated for Ce(Ni0.61Zn0.39)2Si2 and La(Ni0.56Zn0.44)2Si2. Ce(Ni0.61Zn0.39)2Si2 exhibits a Kondo-type ground state. Low temperature specific heat data of La(Ni0.56Zn0.44)2Si2 suggest a spin fluctuation scenario with an enhanced value of the Sommerfeld constant.

Phase relations have been established for the system Ce–Ni–Zn in the isothermal section at 800 °C using electron microprobe analysis and X-ray powder diffraction. Phase equilibria at 800 °C are characterized by a large region for the liquid phase covering most of the Ce-rich part of the diagram, whereas a Zn-rich liquid is confined to a small region near the Zn-corner of the Gibbs triangle. Whereas solubility of Ce in the binary Ni-Zn phases is negligible, mutual solubilities of Ni and Zn at a constant Ce content are large at 800 °C for most Ce–Zn and Ce–Ni compounds. The solid solution Ce(Ni1−xZnx)5 with the CaCu5-type is continuous throughout the entire section and for the full temperature region from 400 to 800 °C. Substitution of Zn by Ni is found to stabilize the structure of CeZn11 to higher temperatures. At 800 °C Ce(NixZn1−x)11 (0.03≤x≤0.22) appears as a ternary solution phase. Similarly, a rather extended solution forms for Ce2(NixZn1−x)17 (0≤x≤0.53). Detailed data on atom site occupation and atom parameters were derived from X-ray structure analyses for single crystals of Ce2+y(NixZn1−x)17, y=0.02, x=0.49 (a=0.87541(3), c=1.25410(4) nm; Th2Zn17 type with space group R 3 ¯ m , R F 2 = 0.018 ) and Ce(Ni0.18Zn0.82)11 (a=1.04302(2), c=0.67624(3)nm, BaCd11 type with space group I41/amd, R F 2 = 0.049 ).

X-ray single crystal (XSC) and neutron powder diffraction data (NPD) were used to elucidate boron site preference for five ternary phases. Ta{sub 3}Si{sub 1-x}B{sub x} (x=0.112(4)) crystallizes with the Ti{sub 3}P-type (space group P4{sub 2}/n) with B-atoms sharing the 8g site with Si atoms. Ta{sub 5}Si{sub 3-x} (x=0.03(1); Cr{sub 5}B{sub 3}- type) crystallizes with space group I4/mcm, exhibiting a small amount of vacancies on the 4a site. Both, Ta{sub 5}(Si{sub 1-x}B{sub x}){sub 3}, x=0.568(3), and Nb{sub 5}(Si{sub 1-x}B{sub x}){sub 3}, x=0.59(2), are part of solid solutions of M{sub 5}Si{sub 3} with Cr{sub 5}B{sub 3}-type into the ternary M-Si-B systems (M=Nb or Ta) with B replacing Si on the 8h site. The D8{sub 8}-phase in the Nb-Si-B system crystallizes with the Ti{sub 5}Ga{sub 4}-type revealing the formula Nb{sub 5}Si{sub 3}B{sub 1-x} (x=0.292(3)) with B partially filling the voids in the 2b site of the Mn{sub 5}Si{sub 3} parent type. - Graphical abstract: The crystal structures of a series of compounds have been solved from X-ray single crystal diffractometry revealing details on the boron incorporation. Highlights: Black-Right-Pointing-Pointer Structure of a series of compounds have been solved by X-ray single crystal diffractometry. Black-Right-Pointing-Pointer Ta{sub 3}(Si{sub 1-x}B{sub x}) (x=0.112) crystallizes with the Ti{sub 3}P-type,more » B and Si atoms randomly share the 8g site. Black-Right-Pointing-Pointer Structure of Nb{sub 5}Si{sub 3}B{sub 1-x} (x=0.292; Ti{sub 5}Ga{sub 4}-type) was solved from NPD.« less

Uranyl(VI) 5,5'-azobis[tetrazolide] pentahydrate was synthesized and characterized using X-ray crystallography, elemental analysis, UV/vis, MIR, FIR, and Raman spectroscopy. It is the second-most nitrogen rich compound of uranium (26.72 wt % N) and only the second structurally characterized uranium complex with a tetrazole ligand described in the literature. The compound's structure is characterized by an exceptionally small uranyl angle of 172.4(1)°, which provides information on the coordination properties of tetrazole ligands as they affect the donor's environment by strong steric and perhaps electrostatic repulsion. The compound showed luminescence under excitation with a near UV laser. The mean lifetime of its excited state was shorter than in the case of UO(2)(NO(3))(2)·6H(2)O, indicating quenching by the ligand. Despite its high nitrogen content (and thus potentially explosive character), the title compound proved to be stable even under neutron radiation causing induced fission processes.

The crystal structures of a series of compounds have been solved from X-ray single crystal diffractometry: Mo(CuxAl1−x)6Al4 (x = 0.416), MoNi2−xAl8+x (x = 0.165), WNi2−x−y□yAl8+x−z□z, (x = 0.162, y = 0.015, z = 0.010) and ReNi2Al8−x (x = 0.033). Mo(CuxAl1−x)6Al4 crystallizes with hexagonal symmetry and lattice parameters, a = 0.50030(1) and c = 0.76279(3) nm; space group P6/mmm, No. 191, as an unfilled structure variant of the MgFe6Ge6-type with a vacant 2c site. This structure is made up of alternate blocks of (unfilled) CaCu5 and Zr4Al3 in a ratio of 1:1. A superstructure of this compound (a = a0√3, c = 2c0) was solved with a Rietveld refinement of X-ray powder diffraction data as a fully ordered structure with formula MoCu2Al8−x. It adopts space group P6, No. 168 with lattice parameters a = 0.86769(1), c = 1.52149(2) nm. A Barnighausen tree was derived reflecting the close relation among these two structure types. The compounds {Mo,W,Re}Ni2−xAl8+x crystallize in a novel structure type (ReNi2Al8−x–type; space group Pbam, No. 55). Whereas ReNi2Al8−x is a fully ordered structure with some defects in the two 4g sites occupied by Al, Ni + Al atoms randomly share one crystallographic site in isotypic {Mo,W}Ni2−xAl8+x, which causes splitting of three neighboring Al-sites. Lattice parameters and residual values of the refinements were: a = 1.00320(2), b = 1.51258(3), c = 0.83890(2) nm; RF2 = 0.017 for the Re-compound, a = 1.00664(2), b = 1.53108(2), c = 0.85205(2) nm, RF2 = 0.035 for the Mo-compound and a = 1.00683(2), b = 1.53236(3), c = 0.85232(2) nm; RF2 = 0.024 for the W-compound. As the ReNi2Al8−x-type structure is another superstructure of the hexagonal Mo(CuxAl1−x)6Al4 type, a Barnighausen tree was derived, which documents the close relation among these two structure types. Phase equilibria in the Al-rich corner of W–Ni–Al at 930 °C is also reported showing the presence of a WNi2Al8 phase. Precise atom positions have been derived from X-ray single crystal data for binary Ni2Al3 confirming the space group P 3 ¯ m1 (No. 164). Atom positions and lattice parameters (a = 0.40533(2), c = 0.49038(3) nm) are very close to the parameters hitherto reported in the literature from X-ray powder diffraction data. Vicker’s hardness was measured for all isotypic compounds {Mo,W,Re}Ni2Al8−x revealing a hardness of HV = 965 ± 25 MPa for the Re-containing material, which is higher by about 100 MPa in comparison to the Mo and W containing phases.

Phase relations have been evaluated for the Ta-V-Si system at 1500 and 1200 degrees C. Three ternary phases were found: tau(1)-(Ta,V)(5)Si-3 (Mn5Si3-type), tau(2)-Ta(Ta,V,Si)(2) (MgZn2-type) and tau(3)-Ta(Ta,V,Si)(2) (MgCu2-type). The crystal structure of tau(2)-Ta(Ta,V,Si)(2) was solved by X-ray single crystal diffraction (space group P6(3)/mmc). Atom order in the crystal structures of tau(1)-(Ta,V)(5)Si-3 (Mn5Si3 type) and tau(3)-Ta(Ta,V,Si)(2) was derived from X-ray powder diffraction data. A large homogeneity range was found for tau(1)-(TaxV1-x)(5)Si-3 revealing random exchange of Ta and V at a constant Si content. At 1500 degrees C, the end points of the tau(1)-phase solution (0.082

Hezuolinite is a new mineral species occurring as an accessory mineral in the Saima alkaline complex in Liaoning Province, NE China. The mineral occurs in a green-aegirine nepheline syenite as non-metamict grains and is associated with microcline, nepheline, aegirine, biotite, eudialyte, rinkite and titanite. The anhedral crystals are several hundred micrometres in size. The mineral is black with dark-brown streak. It is translucent with a resinous luster. Cleavage or parting was not observed. It is brittle with a conchoidal fracture. The hardness is VHN 100 683–964 kg mm −2 (5.5–6 on Mohs’ scale). The measured density is 4.28 g cm −3 , and the calculated value is 4.30 g cm −3 from the empirical chemical formula. Optically, hezuolinite is biaxial negative, with n > 1.8 and 2V = 75°. The dispersion is strong with r > v . The mineral shows a strong pleochroism, from pale brown to dark brown. The average of twenty-five analyses leads to the empirical formula (Sr 2.15 Ce 0.55 La 0.49 Ca 0.49 Na 0.12 Nd 0.09 Pr 0.03 Th 0.03 Sm 0.01 Eu 0.01 ) ∑3.98 (Zr 0.82 Fe 2+ 0.14 Hf 0.02 Mn 0.01 ) ∑1.00 (Ti 1.38 Fe 3+ 0.36 Fe 2+ 0.14 Al 0.04 Nb 0.02 ) ∑1.94 Ti 2 O 8 (Si 2.01 O 7 ) 2 , on the basis of O = 22. The simplified formula is (Sr, REE ) 4 Zr(Ti,Fe 3+ ,Fe 2+ ) 2 Ti 2 O 8 (Si 2 O 7 ) 2 , ideally Sr 2 REE 2 Zr(Fe 2+ )Ti 3 O 8 (Si 2 O 7 ) 2 . The five strongest reflections in the X-ray powder-diffraction pattern [ d in A (I)( hkl )] are: 2.98(100)(−204), 3.02(90)(−313), 1.96(90)(024), 2.18(40)(−422), and 2.84(70)(020). The structure was solved and refined in space group C 2/ m , with a = 13.973(3), b = 5.6984(11), c = 11.988(2) A, β = 114.10(1) °, V = 871.3(3) A 3 , Z = 2, to R1 = 0.037, wR2 = 0.097. The structure of hezuolinite is similar to rengeite. The changes of Sr-O, Zr-O and Ti(1)-O distances confirm partial substitutions of REE for Sr, and Fe for Ti. The sites of O(1), O(2) and O(3) of the hezuolinite structure ( C 2/ m ) are split into O(1) and O(1′), O(2) and O(2′), O(3) and O(3′) sites in the rengeite structure ( P 2 1 / a ), respectively. The Si(1)-O(7)-Si(2) angle in hezuolinite is 175.8°, and is significantly less bent than in rengeite (169.7°). The observed systematic extinctions are in agreement with space group C 2/ m . Hezuolinite is a member of the perrierite-subgroup and can be considered as a chemical intermediate between rengeite and perrierite.

Crystals of Zn(NO3)2· H2O and Mn(NO3)2· 2 H2O were synthesized by heating melts of the respective penta- or hexahydrates. Single crystal X-ray diffraction of the two highly hygroscopic phases reveals new sheet-structure types: Zn(NO3)2· H2O [Pbca,a= 9.722(1),b= 5.865(1),c= 17.799(3) Å (120 K),Z= 8,R1= 0.025]; Mn(NO3)2· 2 H2O [P212121,a= 5.921(1),b= 8.835(1),c= 22.882(3) Å (120 K),Z= 8,R1= 0.020]. Zn(NO3)2· H2O is built of only one kind of complicated, corrugated sheets held together by hydrogen bonds, while Mn(NO3)2· 2 H2O is built of alternating sheets with Mn in 6- and 7-fold coordination, respectively, again interconnected by hydrogen bonds. While in Zn(NO3)2· H2O the hydrogen bond system is quite clear-cut, this is not the case in Mn(NO3)2· 2 H2O. Contrary to expectation, the thermal expansion is not clearly largest perpendicular to the sheets in both compounds.In the well known structures of the nitrate dihydrates of Mg, Co and Ni new refinements allowed to locate the hydrogen atoms.Together with Mn(II) nitrate monohydrate and the dihydrates of Mg, Co, Ni, Zn and Cd the two new nitrates form an interesting group of sheet structures.