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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.

The crystal structures of three Al-rich compounds have been solved from X-ray single crystal diffractometry: τ(1)-MoPd(2-x)Al(8+x) (x = 0.067); τ(7)-Zr(Cu(1-x)Al(x))(12) (x = 0.514) and τ(9)-ZrCu(1-x)Al(4) (x = 0.144). τ(1)-MoPd(2-x)Al(8+x) adopts a unique structure type (space group Pbcm; lattice parameters a = 0.78153(2), b = 1.02643(3) and c = 0.86098(2) nm), which can be conceived as a superstructure of the Mo(Cu(x)Al(1-x))(6)Al(4) type. Whereas Mo-atoms occupy the 4d site, Pd(2) occupies the 4c site, Al and Pd(1) atoms randomly share the 4d position and the rest of the positions are fully occupied by Al. A Bärnighausen tree documents the crystallographic group-subgroup relation between the structure types of Mo(Cu(x)Al(1-x))(6)Al(4) and τ(1). τ(7)-Zr(Cu(1-x)Al(x))(12) (x = 0.514) has been confirmed to crystallize with the ThMn(12) type (space group I4/mmm; lattice parameters a = 0.85243(2) and c = 0.50862(3) nm). In total, 4 crystallographic sites were defined, out of which, Zr occupies site 2a, the 8f site is fully occupied by Cu, the 8i site is entirely occupied by Al, but the 8j site turned out to comprise a random mixture of Cu and Al atoms. The compound τ(9)-ZrCu(1-x)Al(4) (x = 0.144) crystallizes in a unique structure type (space group P4/nmm; lattice parameters a = 0.40275(3) and c = 1.17688(4) nm) which exhibits full atom order but a vacancy (14.4%) on the 2c site, shared with Cu atoms. τ(9)-ZrCu(1-x)Al(4) is a superstructure of Cu with an arrangement of three unit cells of Cu in the direction of the c-axis. A Bärnighausen tree documents this relationship. The ZrCu(1-x)Al(4) type (n = 3) is part of a series of structures which follow this building principle: Cu (n = 1), TiAl(3) (n = 2), τ(5)-TiNi(2-x)Al(5) (n = 4), HfGa(2) (n = 6) and Cu(3)Pd (n = 7). A partial isothermal section for the Al-rich part of the Mo-Pd-Al system at 860 °C has been established with two ternary compounds τ(1)-MoPd(2-x)Al(8+x) and τ(2) (unknown structure). The Vickers hardness (H(v)) for τ(1) was found to be 842 ± 40 MPa.

The isothermal section for the system Ce–Zn–B has been established at 800 °C using electron microprobe analysis and X-ray powder diffraction. No ternary compounds exist and mutual solid solubilities of binary phases are negligible. In the concentration range of 10.0–10.5 at% Ce two structural modifications have been confirmed: high temperature βCe2Zn17 above ∼750 °C with the Th2Zn17 type (R3m, a=0.90916(4) nm, c=1.3286(1) nm) and low temperature αCeZn7 (Ce1−xZn5+2x; x∼0.33) up to 750 °C for which we attributed the TbCu7 type (P6/mmm, a=0.52424(2), c=0.44274(1) nm). The crystal structure of CeZn7 was derived from the Rietveld refinement of X-ray powder intensities. Precise data on atom site distribution and positional parameters have been furthermore provided from X-ray single crystal refinements for two compounds, for which crystal structures hitherto have only been derived from X-ray diffraction photographs: Ce3Zn11 (Immm, a=0.45242(2) nm, b=0.88942(3) nm, c=1.34754(4) nm) and Ce3Zn22 (I41/amd; a=0.89363(2) nm, c=2.1804(5) nm).

Chemical and structural variations of 11 minerals of the cancrinite group having an Al,Si,O framework of the AB type are summarized and discussed. The total number of chemically studied samples is 360 (our data and literature data): cancrinite 192 and 35, vishnevite 21 and 13, cancrisilite 19 and 10, kyanoxalite and oxalate-rich intermediate members of the cancrinite– kyanoxalite series 12 and 0, davyne 10 and 23, depmeierite 2 and 0, balliranoite 1 and 0, hydroxycancrinite 0 and 1, quadridavyne 0 and 10, microsommite 0 and 8, and pitiglianoite 0 and 3. We provide original structural data for nine samples of distinct varieties of cancrinite and one sample of cancrisilite, as well as published structural data on the above-listed minerals. The major topics are the distribution and ratios of extra-framework components, cations (Na + , Ca 2+ , K + ), anions (CO 3 2− , SO 4 2− , Cl − , C 2 O 4 2− , PO 4 3− ) and H 2 O, with special emphasis on oxalate and phosphate anions. The idealized formula of cancrinite has been refined: Na 7 Ca[Al 6 Si 6 O 24 ](CO 3 ) 1.5 •2H 2 O. The solid-solution series with coupled substitutions in the framework and extra-framework portions are discussed, as is the genetic aspect of crystal chemistry of cancrinite-group minerals with a AB -type framework.

Elpidite Na2ZrSi6O15 · 3H2O [space group Pbcm, a = 7.1312(12), b = 14.6853(12), and c = 14.6349(15) A] from Khan Bogdo (Mongolia) and its K- and Rb-exchanged forms K1.78Na0.16H0.06ZrSi6O15 · 0.85H2O [Cmce, a = 14.054(3), b = 14.308(3), and c = 14.553(3) A] and Na1.58Rb0.2H0.22ZrSi6O15 · 2.69H2O [Pbcm, a = 7.1280(10), b = 14.644(3), and c = 14.642(3) A] that were obtained by cation exchange at 90°C, as well as K1.84Na0.11H0.05ZrSi6O15 · 0.91H2O [Cmce, a = 14.037(3), b = 14.226(3), and c = 14.552(3) A] and Rb1.78Na0.06H0.16ZrSi6O15 · 0.90H2O [Cmce, a = 14.2999(12), b = 14.4408(15), and c = 14.7690(12) A], obtained at 150°C are studied by single-crystal X-ray diffraction and IR spectroscopy. The base of the structures is a heteropolyhedral Zr-Si-O framework whose cavities accommodate Na (K, Rb) cations and H2O molecules.

The crystal structures of three ternary Ni-Zn borides have been elucidated by means of X-ray single-crystal diffraction (XSC) and X-ray powder diffraction techniques (XPD) in combination with electron microprobe analyses (EMPA) defining the Ni/Zn ratio. Ni(21)Zn(2)B(24) crystallizes in a unique structure type (space group I4/mmm; a = 0.72103(1) nm and c = 1.42842(5) nm; R(F)(2) = 0.017), which contains characteristic isolated cages of B(20) units composed of two corrugated octogonal boron rings, which are linked at four positions via boron atoms. The B(20) units appear to have eight-membered rings on all six faces like the faces of a cube. Each face is centered by a nickel atom. The six nickel atoms are arranged in the form of an octahedron nested within the B(20) unit. Such a boron aggregation is unique and has never been encountered before in metal-boron chemistry. The crystal structure of Ni(12)ZnB(8-x) (x = 0.43; space group Cmca, a = 1.05270(2) nm, b = 1.45236(3) nm, c = 1.45537(3) nm; R(F)(2) = 0.028) adopts the structure type of Ni(12)AlB(8) with finite zigzag chains of five boron atoms. The compound Ni(3)ZnB(2) crystallizes in a unique structure type (space group C2/m, a = 0.95101(4) nm, b = 0.28921(4) nm, c = 0.84366(3) nm, β = 101.097(3)°, and R(F)(2) = 0.020) characterized by B(4) zigzag chain fragments with B-B bond lengths of 0.183-0.185 nm. The Ni(3)ZnB(2) structure is related to the Dy(3)Ni(2) type.

Nanlingite was first described as a new mineral from a dolomitic limestone along a contact between greisenized granite and dolomitic limestone in the Nanling area, Hunan Province, China. The structure was solved and refined on single-crystal X-ray data in space group R 3 m , with a = 10.2114(10), c = 25.689(3) A, V = 2319.2(6) A 3 , to R1 = 0.021, wR2 = 0.049. The chemical formula of nanlingite is Na(Ca, Li, Na) 6 (Mg, Fe) 12 (AsO 3 ) 2 [Fe(AsO 3 ) 6 ] F 14 with Z = 3 according to the crystal structure refinement. The complex framework is formed by edge- and corner-sharing of distorted NaF 8 and CaF 4 O 4 cubes, MgF 2 O 4 octahedra, and AsO 3 trigonal pyramids. The lithium atom occupies (22 %) the split site at 0.58(2) A from the main Ca site and exhibits a five-fold coordination with 2.21 A. The iron atom (at 3 b , site symmetry 3m) is surrounded by six As atoms of AsO 3 groups at a distance of 2.40 A with the lone-pair electrons pointing towards the central atom. This [Fe(AsO 3 ) 6 ] cluster is a novel configuration in the crystal chemistry of minerals. According to Mossbauer spectra and electron energy-loss spectroscopy data the oxidation state of Fe in nanlingite is mainly Fe II with a low-spin state. In the configuration of arsenite groups, the distance = 1.73 A of the [Fe(AsO 3 ) 6 ] clusters is shorter than the normal range. The empirical crystal-chemical formula for nanlingite is (Na 0.90 Li 0.10 )∑ 1.00 (Ca 4.41 Li 1.06 Mg 0.17 Na 0.06 Mn 0.05 □ 0.25 )∑ 6.00 (Mg 11.38 Fe 3+ 0.30 Al 0.29 Ti 0.03 )∑ 12.00 (AsO 3 ) 2 [Fe II (AsO 3 ) 6 ](F 13.77 OH 0.16 )∑ 13.93 .

In the Au-Ba-Ge system the clathrate type I solid solution, Ba8Au x Ge46−x−y □ y , extends at 800 °C from binary Ba8Ge43□3 (□ is a vacancy) to Ba8Au6Ge40. For the clathrate phase (1 ≤ x ≤ 6) cubic primitive symmetry (space group $$ Pm{\bar{{3}}}n $$ ) was confirmed by x-ray powder diffraction assisted by x-ray single crystal analyses of Ba8Au4.6Ge40.3□1.1. The lattice parameters of the solid solution show an almost linear increase with increasing gold content. Site preference from x-ray refinement shows that gold atoms preferably occupy the 6d site in random mixture with Ge and vacancies, which vanish at the solubility limit. Clathrate type ΙX (Ba6Ge25 type) has a maximum solubility of 2.7 at.% gold at 800 °C. Phase equlilibria at 800 °C are characterized by four ternary phases in the investigated region up to 33.3 at.% barium. The homogeneity range of Ba(Au1−x Ge x )2 (AlB2-type) and BaAu1+x Ge3−x has been established: Ba(Au1−x Ge x )2 extends from BaAu0.5Ge1.5 to BaAu0.9Ge1.1 and BaAu1+x Ge3−x from BaAu1.1Ge2.9 (BaNiSn3-type) to BaAu2.7Ge1.3 (Ce(Ni,Sb)4-type). The crystal structures of two phases in the gold-rich part have been determined from single crystal x-ray data and were found to form new structure types: BaAu3Ge with BaAu3Ge-type (space group P4/nmm, a = 0.6459(2), c = 0.5487(2) nm) and BaAu5+x Ge2−x (x = 0, BaAu5Si2-type, space group Pnma, a = 0.8981(2), b = 0.7106(2) and c = 1.0363(2) nm), the latter revealing with increasing gold content a closely related derivative structure type (BaAu5.3Ge1.7, $$ a = a_{{{\text{BaAu}}_{5} {\text{Si}}_{2} }} ,\;b = b_{{{\text{BaAu}}_{5} {\text{Si}}_{2} }} ,\;c = 2c_{{{\text{BaAu}}_{5} {\text{Si}}{}_{2}}} $$ ). Transport properties and particularly the thermoelectric behavior were studied for Ba8Au6Ge40.

Eirikite, ideally, KNa 6 [Be 2 (Si 15 Al 3 ) ∑= 18 O 39 F 2 ], is a new mineral species from the Vesle Aroya island in the Langesundsfjord district, Larvik, Vestfold, Norway. It is the potassium analogue of leifite, NaNa 6 [Be 2 (Si 15 Al 3 ) ∑=18 O 39 F 2 ], and telyushenkoite, CsNa 6 [Be 2 (Si 15 Al 3 ) ∑= 18 O 39 F 2 ]. An average of five electron microprobe analyses gave Na 2 O 13.38, K 2 O 3.13, Al 2 O 3 11.08, SiO 2 66.03, F 2.70, BeO 3.65 (calc.), O = F −1.14, total 98.83 wt. %, resulting in the empirical formula K 0.91 Na 5.92 [Be 2 (Si 15.07 Al 2.98 ) ∑=18.05 ]O 39 (F 1.95 O 0.05 ); infrared spectroscopy indicates the absence of OH and H 2 O. Eirikite occurs as both finely or coarsely fibrous, monomineralic aggregates and bundles up to 3 cm across, wholly or partly filling voids between larger microcline crystals. Individual acicular-prismatic crystals show the forms {1010}and {0001}. Eirikite also occurs as aggregates up to 100 cm 3 in volume, built of interlocking, radiating fibrous groups, each up to 5 mm across, intergrown with large amounts of small zircon crystals and penetrated by aegirine crystals. Polylithionite, albite, eudialyte, catapleiite and pyrochlore can be found within these aggregates. Eirikite is white to colourless with a white streak, a vitreous to silky lustre, Mohs hardness of 6; it is brittle with an uneven to conchoidal fracture, and with a good {1010} cleavage. The mineral is uniaxial positive, ω =1.517(1) and e = 1.521(1), and nonpleochroic; D meas = 2.59(1) g/cm 3 , D calc = 2.577 g/cm 3 (from the empirical chemical formula) and 2.584 g/cm 3 (from the crystal structure determination). Eirikite is trigonal, P 3 m 1 (no. 164), with a = 14.3865(9) A, c = 4.8733(4) A, V = 873.5(1) A 3 , and Z = 1, refined from X-ray powder diffraction data. The five strongest lines in the X-ray powder pattern are [d (in A) (I/I 0 )(hkl)]: 4.710(29)(120), 4.153(21)(030), 3.386(70)(211), 3.161(100)(031), and 2.466(31)(231). The crystal structure, which was determined from single-crystal X-ray intensity data and refined to R 1( F ) = 1.99 %, is a framework of corner-sharing (Si,Al)O 4 and BeO 3 F tetrahedra ( = 1.610 A), leading to chain and ring units. Voids in the framework are occupied by K ( = 3.105 A), and seven-coordinated Na atoms ( = 2.542 A). The B site, which is vacant in telyushenkoite and partly occupied by water molecules in leifite, is nearly vacant in eirikite.

Phase relations in the system Ce–Zn–Si have been determined for the isothermal section at 800 °C using electron microprobe analysis and X-ray powder diffraction. Phase equilibria are characterized by extended solid solutions along the section CeSi 2 –CeZn 2 , which form a structurally related sequence of structure types: Ce(Zn x Si 1− x ) 2 (αThSi 2 -type, 0 ≤ x ≤ 0.32), τ 2 -Ce(Zn x Si 1− x ) 2 (AlΒ 2 -type, 0.36 ≤ x ≤ 0.76) and Ce(Zn 1− x Si x ) 2 (CeCu 2 -type, 0 ≤ x ≤ 0.18). Silicon stabilizes the ternary compound τ 1 -Ce 7 Zn 21 (Zn 1− x Si x ) 2 , (0.28 ≤ x ≤ 0.98) for which the crystal structure was derived from X-ray diffraction data for a single crystal of Ce 7 Zn 21 (Zn 1− x Si x ) 2 ( x = 0.28; unique structure type, Pbam ; a = 1.55722(3) nm, b = 1.71942(3) nm, c = 0.44772(1) nm; R F = 0.029). The structure of Ce 7 Zn 21 (Zn 1− x Si x ) 2 can be considered as an arrangement of slightly distorted building blocks of Cu 3 Au-type (Zn[Ce 4 Zn 8 ]) and BaAl 4 -type (Ce[Ce 2 Zn 10 M 4 ] and Ce[Ce 2 Zn 13 M 2 ]), arranged in form of a zig-zag string of face-sharing units…Cu 3 Au–BaAl 4 –BaAl 4 –BaAl 4 –Cu 3 Au… running parallel to the b -axis. Structural analyses proved isotypism for homologous La 7 Zn 21 (Zn 1− x Si x ) 2 ( x = 0.27), Ce 7 Zn 21 (Zn 1− x Si x ) 2 -type, Pbam ; a = 1.56817(2) nm, b = 1.72923(3) nm, 0.450887(7) nm; X-ray single crystal data and La(Zn x Si 1− x ) 2 , ( x = 0.56, AlΒ 2 -type, P6/ mmm , a = 0.42775(4) nm, c = 0.42832(4) nm; X-ray powder data). The structure types of the ternary compounds τ 3 -Ce(Zn x Si 1− x ), 0.17 ≤ x ≤ 0.23, and τ 4 -Ce 40 Zn 37 Si 23 (in at.%) are still unknown.

Bendadaite, ideally Fe2+Fe23+ (AsO4)2(OH)2·4H2O, is a new member of the arthurite group. It was found as a weathering product of arsenopyrite on a single hand specimen from the phosphate pegmatite Bendada, central Portugal (type locality). Co-type locality is the granite pegmatite of Lavra do Almerindo (Almerindo mine), Linópolis, Divino das Laranjeiras county, Minas Gerais, Brazil. Further localities are the Veta Negra mine, Copiapó province, Chile; Oumlil-East, Bou Azzer district, Morocco; and Pira Inferida yard, Fenugu Sibiri mine, Gonnosfanadiga, Medio Campidano Province, Sardinia, Italy.Type bendadaite occurs as blackish green to dark brownish tufts (P21/c, with a = 10.239(3) Å, b = 9.713(2) Å, c = 5.552(2) Å, β = 94.11(2)°, V = 550.7(2) Å3, Z = 2. Electron-microprobe analysis yielded (wt.%): CaO 0.04, MnO 0.03, CuO 0.06, ZnO 0.04, Fe2O3 (total) 43.92, Al2O3 1.15, SnO2 0.10, As2O5 43.27, P2O5 1.86, SO3 0.03. The empirical formula is (Fe2+0.52Fe3+0.32☐0.16)Σ1.00(Fe3+1.89Al0.11)Σ2.00(As1.87P0.13)Σ2.00O8(OH)2.00·4H2O based on 2(As,P) and assuming ideal 8O, 2(OH), 4H2O and complete occupancy of the ferric iron site by Fe3+ and Al. Optically, bendadaite is biaxial, positive, 2Vest. = 85±4°, 2Vcalc. = 88°, with α 1.734(3), β 1.759(3), γ 1.787(4). Pleochroism is medium strong: X pale reddish brown, Y yellowish brown, Z dark yellowish brown; absorption Z > Y > X, optical dispersion weak, r > v. Optical axis plane is parallel to (010), with X approximately parallel to a and Z nearly parallel to c. Bendadaite has vitreous to sub-adamantine luster, is translucent and non-fluorescent. It is brittle, shows irregular fracture and a good cleavage parallel to {010}. Dmeas. 3.15±0.10 g/cm3, Dcalc. 3.193 g/cm3 (for the empirical formula). The five strongest powder diffraction lines [d in Å (I)(hkl)] are 10.22 (10)(100), 7.036 (8)(110), 4.250 (5)(111), 2.865 (4)(), 4.833 (3)(020,011). The d spacings are very similar to those of its Zn analogue, ojuelaite. The crystal structure of bendadaite was solved and refined using a crystal from the co-type locality with the composition (Fe2+0.95☐0.05)Σ1.00(Fe3+1.80Al0.20)Σ2.00(As1.48P0.52)Σ2.00O8(OH)2·4H2O (R = 1.6%), and confirms an arthurite-type atomic arrangement.

Two series of intermetallic alloys, RT2Si and RTSi2, have been synthesized from stoichiometric compositions. The crystal structures of EuPt1+xSi2−x (CeNiSi2-type), CeIr2Si (new structure type), YbPd2Si and YbPt2Si (both YPd2Si-type) have been elucidated from X-ray single crystal CCD data, which were confirmed by XPD experiments. The crystal structures of LaRh2Si and LaIr2Si (CeIr2Si-type), {La,Ce,Pr,Nd}AgSi2 (all TbFeSi2-type), and EuPt2Si (inverse CeNiSi2-type) were characterized by XPD data. RT2Si/RTSi2 compounds were neither detected in as-cast alloys Sc25Pt50Si25, Eu25Os25Si50 and Eu25Rh25Si50 nor after annealing at 900 °C. Instead, X-ray single crystal data prompted Eu2Os3Si5 (Sc2Fe3Si5-type) and EuRh2+xSi2−x (x=0.04, ThCr2Si2-type) as well as a new structure type for Sc2Pt3Si2 (own type).

The formation and crystal chemistry of ternary clathrates in the Ba-Cu-Si system were investigated on a series of compounds Ba8Cu x Si46−x (3 ≤ x ≤ 8). The phase diagram around the clathrate phase was constructed at 800°C, revealing a homogeneity range from Ba8Cu3.4Si42.6 to Ba8Cu4.8Si41.2. Structural investigations confirmed that the clathrates in this system crystallize with cubic primitive symmetry, in the type I clathrate structure (space group Pm $$ \bar{3} $$ n). Single-crystal x-ray diffraction indicates that the Cu atoms partially substitute for Si atoms on the 6d site; no vacancies are observed.

Phase equilibria and crystal structures of ternary compounds were determined in the systems Ce–Pd–B and Yb–Pd–B at 850 °C in the concentration ranges up to 45 and 33 at% of Ce and Yb, respectively, employing X-ray single crystal and powder diffraction. Phase relations in the Ce–Pd–B system at 850 °C are governed by formation of extended homogeneity fields, τ2-CePd8B2−x (0.10 The Yb–Pd–B system is characterized by one ternary compound, τ1-Yb2Pd14B5, forming equilibria with extended solution YbPd3Bx, YbB6, Pd5B2 and Pd3B. The crystal structures of both Yb2Pd14B5 and isotypic Lu2Pd14B5 were determined from X-ray Rietveld refinements and found to be closely related to the Y2Pd14B5-type (I41/amd). The crystal structure of binary Yb5Pd2−x (Mn5C2-type) was confirmed from X-ray single crystal data and a slight defect on the Pd site (x=0.06) was established. The three structures τ1-Ce6Pd47−xB6, τ2-CePd8B2−x and τ3-Ce3Pd25−xB8−y are related and can be considered as the packings of fragments observed in Nd2Fe14B structure with different stacking of common structural blocks. Physical properties for Yb2Pd13.6B5 (temperature dependent specific heat, electrical resistivity and magnetization) yielded a predominantly Yb-4f13 electronic configuration, presumably related with a magnetic instability below 2 K. Kondo interaction and crystalline electric field effects control the paramagnetic temperature domain.

A series of rare earth element (REE) mixed-anion 5,5-azobis(1H-tetrazol-1-ide)-carbonate ([REE2(ZT)(2)CO3(H2O)(10)] 2H(2)O;REE = lanthanides plus yttrium) coordination compounds were synthesized, characterized, and analyzed. Syntheses by simple metathesis reactions under a CO2 atmosphere were carried out at ambient (La-Gd and Ho) and elevated pressures (55 bar;Tb, Dy, Er, Tm, Yb, and Y). The resulting crystalline materials were characterized principally by single-crystal X-ray diffraction and vibrational spectroscopy (infrared and Raman). All materials are structurally isotypic, crystallizing in the space group C2/c and show nearly identical spectroscopic properties for all the elements investigated. Cell parameters, bond lengths, and bond angles differ marginally, revealing only a slight variation coinciding with the lanthanide (Ln) contraction, that is, the change in the ionic radii of the trivalent rare earth elements. The herein reported series of rare earth element azobis[tetrazolide]-carbonates represents a remarkable exception as they are a series of isotypic REE coordination compounds with tetrazolide-derived ligands unaffected by the gadolinium break.

Two tau-borides, τ-(Fe0.54Ir0.46)20Fe3B6 and τ-(Co0.64Ir0.36)21Co0.16B4B6 were studied by X-ray powder and single crystal diffraction with respect to precise atom site distribution and metal atom ordering. X-ray structure determination for a single crystal of τ-(Fe0.54Ir0.46)20Fe3B6 revealed isotypism with a partially ordered Cr23C6-type (space group Fm 3 ¯ m, a = 1.11020 nm) but with a high degree of random replacement of Fe/Ir atoms in sites 48h and 32f. X-ray single crystal data for τ-(Co0.64Ir0.36)21Co0.16B4B6 showed a novel low-symmetry structure variant of tau-borides characterized by a noncentrosymmetric distribution of boron tetrahedra and a defect Co-site (space group F 4 ¯ 3m as a translationengleiche, nonisomorphic maximal subgroup of index 2 of Fm 3 ¯ m, a = 1.09359 nm). The crystal structures of both τ-phases are described with nested polyhedra geometrically related to the α-Mn structure. Stability ranges and various structural arrangements of (MM')23B6 phases are discussed. The crystal structures of (Fe1−xIrx)3B (x = 0.24; X-ray single crystal data; Fe3C-type, space group Pnma, a = 0.5430(2), b = 0.6958(2) nm, c = 0.4654(2) nm), and of isotypic (Fe1−xRhx)3B (XPD Rietveld refinement, x = 0.25, space group Pnma, a = 0.54560(1) nm, b = 0.69552(1) nm, c = 0.46169(1) nm) show both a high degree of randomness in the metal sites.

In this third part of our research on the 5,5′-azobis[1H-tetrazol-1-ides] (ZT) of the lanthanoids, we present two compounds with La2(ZT)3 moieties with very different coordination modes between the cations and the anions. One La2(ZT)3-containing compound is interesting, because it contains trimeric La3(ZT)3III cations, which are arranged in a windmill-like structure. Moreover, the first double salt of a ZT compound, namely the carbonate compound La2(ZT)2(CO3)⋅12 H2O, is presented and discussed. Another highlight of nitrogen chemistry is the first molecular structure of a 5-azido-2H-tetrazole (CHN7) molecule, in the form of the spectacular compound Dy2(ZT)3⋅4 CHN7⋅24 H2O. This is the first known complete molecular structure of an azidotetrazole molecule (the organic molecule with the highest nitrogen-content: 88.3% N). All compounds have been characterized completely including elemental analyses, vibrational (IR and Raman) spectroscopy, and X-ray crystal-structure determination. We summarize our ‘nitrogen-rich compounds of the lanthanoids’ project and extensively discuss selected literature on this topic and compare previously published results with ours.

Liversidgeite, ideally Zn 6 (PO 4 ) 4 ·7H 2 O, is a new mineral from Block 14 Opencut, Broken Hill, New South Wales, Australia. The mineral occurs as white, thin, bladed crystals and as hemispherical aggregates of radiating crystals in cavities in sphalerite-galena ore. Associated minerals are anglesite, pyromorphite, greenockite, sulfur, and an unknown Zn phosphate sulfate. Individual crystals are up to 0.1 mm in length and 0.05 mm across. Liversidgeite is transparent to translucent, with a vitreous luster and a white streak. It is brittle with an irregular fracture, the Mohs hardness is ~3–3.5, and the observed and calculated densities are 3.21(2) and 3.28 g/cm 3 , respectively. Chemical analysis by electron microprobe gave ZnO 54.62, MnO 0.49, PbO 0.18, P 2 O 5 32.62, As 2 O 5 0.65, SO 3 0.35, H 2 O 14.04, total 102.95 wt%, with H 2 O content derived from the refined crystal structure. The empirical formula calculated on the basis of 23 O atoms is Pb 0.01 (Zn 5.86 Mn 0.06 ) ∑5.92 (P 4.01 As 0.05 S 0.04 ) ∑4.10 O 16.20 ·6.8H 2 O. Liversidgeite is triclinic, space group P 1, with a = 8.299(1), b = 9.616(1), c = 12.175(1) A, α = 71.68(1), β = 82.02(1), γ = 80.18(1)°, V = 905.1(2) A 3 (single-crystal data), and Z = 2. The six strongest lines in the X-ray powder diffraction pattern are [ d (A), ( I ), ( hkl )]: 8.438 (80) (011), 3.206 (60) (013), 2.967 (75) (212, 114), 2.956 (75) (212), 2.550 (85) (233, 213), 2.537 (100) (221, 014, 311). The crystal structure of liversidgeite was refined to an R 1 index of 5.95% based on 3054 observed ( F o > 4σ F o ) reflections measured with Mo K α X-radiation. The structure is based on two distinct, infinite zigzag chains of edge-sharing Znϕ 6 (ϕ = unspecified anion) octahedra that extend in the a direction. The chains link to each other via common corners and also via corner-sharing PO 4 tetrahedra, forming sheets parallel to the (011) plane. The sheets link via [Zn 2 ϕ 8 ] dimeric building units, comprising edge-sharing Znϕ 5 trigonal bipyramids and Znϕ 4 tetrahedra, resulting in an open framework. Large ellipsoidal channels extend along the a direction and are occupied by interstitial H 2 O groups and the H atoms of the H 2 O groups that coordinate to the Zn cations. An extensive network of hydrogen bonds provides additional linkage between the sheets in the structure, via the interstitial H 2 O groups. The topology of the liversidgeite structure is identical to that of synthetic, monoclinic Zn 2 Co 4 (PO 4 ) 4 (H 2 O) 5 ·2H 2 O.

Tourmaline grains extrcted from rocks within three ultrahigh-pressure (UHP) metamorphic localities have been subjected to a structurally and chemically detailed analysis to test for any systematic behavior related to temperature and pressure. Dravite from Parigi, Dora Maira, Western Alps (peak P - T conditions ~3.7 GPa, 750 °C), has a structural formula of X(Na0.90Ca0.05K0.01□0.04)Y(Mg1.78Al0.99Fe2+0.12Ti4+0.03□0.08)Z(Al5.10Mg0.90)(BO3)3TSi6.00O18V(OH)3W[(OH)0.72F0.28]. Dravite from Lago di Cignana, Western Alps, Italy (~2.7–2.9 GPa, 600–630 °C), has a formula of X(Na0.84Ca0.09K0.01□0.06)Y(Mg1.64Al0.79Fe2+0.48Mn2+0.06Ti4+0.02Ni0.02Zn0.01)Z(Al5.00Mg1.00)(BO3)3T(Si5.98Al0.02)O18V(OH)3W[(OH)0.65F0.35]. “Oxy-schorl” from the Saxonian Erzgebirge, Germany (≥4.5 GPa, 1000 °C), most likely formed during exhumation at >2.9 GPa, 870 °C, has a formula of X(Na0.86Ca0.02K0.02□0.10)Y(Al1.63Fe2+1.23Ti4+0.11Mg0.03Zn0.01) Z(Al5.05Mg0.95)(BO3)3T(Si5.96Al0.04)O18V(OH)3W[O0.81F0.10(OH)0.09]. There is no structural evidence for significant substitution of [4]Si by [4]Al or [4]B in the UHP tourmaline ( distances ~1.620 A), even in high-temperature tourmaline from the Erzgebirge. This is in contrast to high- T –low- P tourmaline, which typically has significant amounts of [4]Al. There is an excellent positive correlation ( r 2 = 1.00) between total [6]Al (i.e., YAl + ZAl) and the determined temperature conditions of tourmaline formation from the different localities. Additionally, there is a negative correlation ( r 2 = 0.97) between F content and the temperature conditions of UHP tourmaline formation and between F and YAl content ( r 2 = 1.00) that is best explained by the exchange vector YAlO(R2+F)−1. This is consistent with the W site (occupied either by F, O, or OH), being part of the YO6-polyhedron. Hence, the observed Al-Mg disorder between the Y and Z sites is possibly indirectly dependent on the crystallization temperature.

Biachellaite, a new mineral species of the cancrinite group, has been found in a volcanic ejecta in the Biachella Valley, Sacrofano Caldera, Latium region, Italy, as colorless isometric hexagonal bipyramidal-pinacoidal crystals up to 1 cm in size overgrowing the walls of cavities in a rock sample composed of sanidine, diopside, andradite, leucite and hauyne. The mineral is brittle, with perfect cleavage parallel to {10 $$ \bar 1 $$ 0} and imperfect cleavage or parting (?) parallel to {0001}. The Mohs hardness is 5. Dmeas = 2.51(1) g/cm3 (by equilibration with heavy liquids). The densities calculated from single-crystal X-ray data and from X-ray powder data are 2.515 g/cm3 and 2.520 g/cm3, respectively. The IR spectrum demonstrates the presence of SO 4 2− , H2O, and absence of CO 3 2− . Biachellaite is uniaxial, positive, ω = 1.512(1), ɛ = 1.514(1). The weight loss on ignition (vacuum, 800°C, 1 h) is 1.6(1)%. The chemical composition determined by electron microprobe is as follows, wt %: 10.06 Na2O, 5.85 K2O, 12.13 CaO, 26.17 Al2O3, 31.46 SiO2, 12.71 SO3, 0.45 Cl, 1.6 H2O (by TG data), −0.10 −O=Cl2, total is 100.33. The empirical formula (Z = 15) is (Na3.76Ca2.50K1.44)Σ7.70(Si6.06Al5.94O24)(SO4)1.84Cl0.15(OH)0.43 · 0.81H2O. The simplified formula is as follows: (Na,Ca,K)8(Si6Al6O24)(SO4)2(OH)0.5 · H2O. Biachellaite is trigonal, space group P3, a =12.913(1), c = 79.605(5) A; V = 11495(1) A3. The crystal structure of biachellaite is characterized by the 30-layer stacking sequence (ABCABCACACBACBACBCACBACBACBABC)∞. The tetrahedral framework contains three types of channels composed of cages of four varieties: cancrinite, sodalite, bystrite (losod) and liottite. The strongest lines of the X-ray powder diffraction pattern [d, A (I, %) (hkl)] are as follows: 11.07 (19) (100, 101), 6.45 (18) (110, 111), 3.720 (100) (2.1.10, 300, 301, 2.0.16, 302), 3.576 (18) (1.0.21, 2.0.17, 306), 3.300 (47) (1.0.23, 2.1.15), 3.220 (16) (2.1.16, 222). The type material of biachellaite has been deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, Russia, registration number 3642/1.

On the occasion of Carl Auer von Welsbach's 150th birthday in 2008, we investigated the 5,5′-azobis[1H-tetrazol-1-ides] (C2N; (ZT)2−) of the light lanthanoids (Ln) cerium, praseodymium, neodymium, samarium, europium, and gadolinium. Their synthesis was performed by crystallization from aqueous solutions of disodium 5,5′-azobis[1H-tetrazol-1-ide] and the respective lanthanoid nitrate. All compounds are isotypic (triclinic space group P-1) and crystallize according to the general formula [Ln(H2O)7]2(ZT)3⋅10 H2O. The crystal structures of all compounds were determined. A distinct lanthanoid contraction could be established, clearly observable by the decrease in the bond lengths in the LnNO7 polyhedra from the Ce to the Gd compound. Further, and in contrast to the previously published 5,5′-azobis[1H-tetrazol-1-ides] of the heavy yttric earths, the light Ln cations in this study are coordinated not only by H2O molecules but also by one (ZT)2− anion. Further characterization was performed by vibrational (IR and Raman) spectroscopy and elemental analysis.

Phase relations in the ternary system Ce–Pd–Si have been established for the isothermal section at 8001C based on X-ray powder diffraction and EMPA techniques on about 130 alloys, which were prepared by arc-melting under argon or powder reaction sintering. Eighteen ternary compounds have been observed to participate in the phase equilibria at 8001C. Atom order was determined by direct methods from X-ray single-crystal counter data for the crystal structures of t8—Ce3Pd4Si4 (U3Ni4Si4type, Immm; a ¼ 0.41618(1), b ¼ 0.42640(1), c ¼ 2.45744(7) nm), t16—Ce2Pd14Si (own structure type, P4/nmm; a ¼ 0.88832(2), c ¼ 0.69600(2) nm) and also for t18—CePd1� xSix (x ¼ 0.07; FeB-type, Pnma; a ¼ 0.74422(5), b ¼ 0.45548(3), c ¼ 0.58569(4) nm). Rietveld refinements established the atom arrangement in the structures of t5—Ce3PdSi3 (Ba3Al2Ge2-type, Immm; a ¼ 0.41207(1), b ¼ 0.43026(1), c ¼ 1.84069(4) nm) and t13—Ce3� xPd20+xSi6 (0rxr1, Co 20Al3B6-type, Fm3 ¯ m; a ¼ 1.21527(2) nm). The ternary compound Ce2Pd3Si3 (structure-type Ce2Rh1.35Ge4.65, Pmmn; a ¼ 0.42040(1), b ¼ 0.42247(1), c ¼ 1.72444(3) nm) was detected as a high-temperature compound, however, does not participate in the equilibria at 8001C. Phase equilibria in Ce–Pd–Si are characterized by the absence of cerium solubility in palladium silicides. Mutual solubility among cerium silicides and cerium–palladium compounds are significant whereby random substitution of the almost equally sized atom species palladium and silicon is reflected in extended homogeneous regions at constant Cecontent such as for t2—Ce(PdxSi1� x)2 (AlB2-derivative type), t6—Ce(PdxSi1� x)2 (ThSi2-type) and t7—CePd2� xSi2+x. The crystal structures of compounds t4—Ce� 8Pd� 46Si� 46, t12—Ce� 29Pd� 49Si� 22, t15—Ce� 22Pd� 67Si� 11, t17—Ce� 5Pd� 77Si� 18 and t18—CePd1� xSix (x� 0.1) are still unknown.

The crystal structures of ternary compounds RPt3−xSi1−y(R=Y, Tb, Dy, Ho, Er, Tm, Yb) have been elucidated from X-ray single crystal CCD data. All compounds are isotypic and crystallize in the tetragonal space group P4/mbm. The general formula RPt3−xSi1−y arises from defects: x≈0.20, y≈0.14. The crystal structure of RPt3−xSi1−y can be considered as a packing of four types of building blocks which derive from the CePt3B-type unit cell by various degrees of distortion and Pt, Si-defects.

Phase relations at 700 deg. C, 800 deg. C and solidus temperatures have been derived for the clathrate system Ba{sub 8}Cu{sub x}Ge{sub 46-x-y}square{sub y} via X-ray single crystal and powder diffractometry combined with electron probe micro analysis and differential thermal analysis. The ternary clathrate phase derives from binary Ba{sub 8}Ge{sub 43}square{sub 3} and extends up to x=6. Structure investigations define cubic primitive symmetry with the space group type Pm3-barn consistent with a clathrate type I structure throughout the entire homogeneity region 0 =5.5. - Graphical Abstract: Cages and atom thermal displacement parameters in clathrate Ba{sub 8}Cu{sub x}Ge{sub 46-x-y}square{sub y} for Ba{sub 8}Cu{sub 2}Ge{sub 42}square{sub 2} and Ba{sub 8}Cu{sub 6}Ge{sub 40}.

Rare earth basic nitrate hydrates (LnBN) of the general formula [Ln6(μ6–O)(μ3–OH)8(H2O)12(η2–NO3)6](NO3)2·xH2O, (Ln = Y, Sm, Eu, Gd. Tb, Dy, Ho, Er, Tm, Yb, Lu; x = 3, 4, 5, 6) exist at least in seven different structure types (AI–D). The present paper describes and discusses their synthesis and structure determination. The basal building unit, common to all these compounds, is a [Ln6(μ6–O)(μ3–OH)8(H2O)12(η2–NO3)6]2+ cluster of idealized symmetry −32/m. The stoichiometry is completed by non-coordinated (NO3)1− anions and H2O molecules in interstices.

A set of N-rich salts, 3–9, of the heavy lanthanoids (terbium, 3; dysprosium, 4; holmium 5; erbium, 6; thulium, 7; ytterbium, 8; lutetium, 9) based on the energetic 5,5′-azobis[1H-tetrazole] (H2ZT) was synthesized and characterized by elemental analysis, vibrational (IR and Raman) spectroscopy, and X-ray structure determination. The synthesis of the lanthanoid salts 3–9 was performed by crystallization from concentrated aqueous solutions of disodium 5,5′-azobis[1H-tetrazol-1-ide] dihydrate (Na2ZT⋅2 H2O; 1) and the respective Ln(NO3)3⋅5 H2O and yielded large rhombic crystals of the type [Ln(H2O)8]2(ZT)3⋅6 H2O in ca. 70% of the theoretical yield. The compounds 3–9 are isostructural (triclinic space group P) to the previously published yttrium salt 2; they show, however, a clear lanthanoid contraction of several crystallographic parameters, e.g., the cell volume or the LnO bond lengths of the Ln3+ ions and the coordinating H2O molecules. The lanthanoid contraction influences the strengths of the H-bonds, which can be observed as a red shift by 4 cm−1 in the characteristic IR band, in particular from 3595 cm−1 (3) to 3599 cm−1 (9). In good agreement with previous works, 2–9 are purely salt-like compounds without a coordinative bond between the tetrazolide anion and the Ln3+ cation.

BaCo 4.7 Ge 9 (BaCo 5− x Ge 9 , x = 0.29) is a novel ternary compound which forms incongruently from the melt and crystallizes in a unique structure type (space group Pnma ; a = 1.39910(2), b = 0.40218(2), c = 1.69882(2) nm, Z = 4). Isotypic compounds were found with SrCo 4.7 Ge 9 ( a = 1.39389(8), b = 0.39665(1), c = 1.67860(9) nm) and EuCo 4.7 Ge 9 ( a = 1.3910(1), b = 0.39425(2), c = 1.6741(2) nm). Physical properties (electrical resistivity, specific heat, magnetic susceptibility) were studied for BaCo 4.7 Ge 9 and EuCo 4.7 Ge 9 . BaCo 4.7 Ge 9 shows metallic behaviour but neither a superconducting nor a magnetic phase transition was observed for temperatures as low as T = 2 K. Magnetic susceptibility and specific heat data of EuCo 4.7 Ge 9 , evidence the onset of antiferromagnetic order at 18.5 K. Both magnetic ordering and the effective magnetic moment derived verify the Eu 2+ state with a total angular momentum j = 7/2.

Formation and crystal structure of Laves phases in the systems Ti–{Pd,Pt}–Al were investigated employing XPD (X-ray powder diffraction), XSCD (X-ray single crystal diffraction) and EPMA (electron probe microanalysis) techniques. Laves phases with MgZn 2 type (space group: P 6 3 / mmc ) and its variant with the Nb(Ir,Al) 2 -type ( a √3 × a √3 × c supercell of MgZn 2 -type, space group: P 6 3 / mcm ) were found in both systems. Formation of a particular structure type is dependent on temperature and composition. Laves phases with the Nb(Ir,Al) 2 -type form around 25 at.% of Pd,Pt at 950 °C. The MgZn 2 -type Laves phase Ti(Pt,Al) 2 was not observed at 950 °C, but it forms in as-cast alloys at a slightly lower Pt content, Ti 37.8 Pt 19.0 Al 43.2 . In the Ti–Pd–Al system at 950 °C the MgZn 2 -type phase exists at the Pd-poor side of the homogeneity region whilst the Nb(Ir,Al) 2 -type phase is slightly richer in Pd. Phase relations associated with the Ti–Pt–Al Laves phase were established at 950 °C and reveal a new compound TiPtAl that derives from hexagonal ZrBeSi-type (ordered Ni 2 In-type, a = 0.43925(4) nm, c = 0.54844(5); space group P 6 3 / mmc ; R F2 = 0.015 from single crystal data). Atom distribution in the compound shows a slight deviation from full atom order Ti(Pt 0.97 Al 0.03 )(Al 0.98 Pt 0.02 ).

Phase relations in the ternary systems Ce–M–Sb (M=Si, Ge, Sn) in composition regions CeSb2–Sb–M were studied by optical and electron microscopy, X-ray diffraction, and electron probe microanalysis on arc-melted alloys and specimens annealed in the temperature region from 850 to 200 °C. The results, in combination with an assessment of all literature data available, were used to construct solidus surfaces and a series of isothermal sections. No ternary compounds were found to form in the Ce–Si–Sb system whilst Ce12Ge9−xSb23+x (3.3

Alloys with nominal composition Nb(Ni1−xAlx)2 (xAl=0.15, 0.23, 0.30, 0.38, 0.46, 0.54, 0.62, 0.69, 0.77, 0.85) were investigated by means of X-ray powder and single crystal diffraction, optical microscopy, electron probe microanalysis (EPMA) concentrating on structural details of the C14 MgZn2-type Laves phase. Rietveld refinements of X-ray powder data ( 0.23 x Al 0.77 ) revealed that Nb atoms fully occupy the 4f sites, whereas Ni and Al atoms share 6h and 2a sites in a random fashion. Single crystal refinement for Nb(Ni0.54Al0.46)2 confirmed structure type and atom order in line with results from powder diffraction. The characteristic site preferences throughout the series of alloys serve as a basis for the interpretation of the non-linear dependence of unit cell parameters with Al content.

Plimerite, ideally Zn (PO4)3(OH)5, is a new mineral from the Block 14 Opencut, Broken Hill, New SouthWales. It occurs as pale-green to dark-olive-green, almost black, acicular to prismatic and bladed crystals up to 0.5 mm long and as hemispherical aggregates of radiating acicular crystals up to 3 mm across. Crystals are elongated along [001] and the principal form observed is {100} with minor {010} and {001}. The mineral is associated with hinsdalite-plumbogummite, pyromorphite, libethenite, brochantite, malachite, tsumebite and strengite. Plimerite is translucent with a pale-greyish-green streak and a vitreous lustre. It shows an excellent cleavage parallel to {100} and {010} and distinct cleavage parallel to {001}. It is brittle, has an uneven fracture, a Mohs’ hardness of 3.5–4, D(meas.) = 3.67(5) g/cm3 and D(calc.) = 3.62 g/cm3 (for the empirical formula). Optically, it is biaxial negative with α = 1.756(5), β = 1.764(4), γ = 1.767(4) and 2V(calc.) of –63º; pleochroism is X pale-greenish-brown, Y pale-brown, Z pale-bluish-green; absorption Z > X > Y; optical orientation XYZ = cab. Plimerite is orthorhombic, space group Bbmm, unit-cell parameters: a = 13.865(3) Å, b = 16.798(3) Å, c = 5.151(10) Å, V = 1187.0(4) Å3 (single-crystal data) and Z = 4. Strongest lines in the X-ray powder diffraction pattern are [d (A˚ ), I, hkl]: 4.638, (50), (111); 3.388, (50), (041); 3.369, (55), (131); 3.168, (100), (132); 2.753, (60), (115); 2.575, (90), (200); 2.414, (75), (220); 2.400, (50), (221); 1.957, (40), (225). Electron microprobe analysis yielded (wt.%): PbO 0.36, CaO 0.17, ZnO 20.17, MnO 0.02, Fe2O3 29.82, FeO 2.98, Al2O3 4.48, P2O5 32.37, As2O5 0.09, H2O (calc) 6.84, total 97.30 (Fe3+/Fe2+ ratio determined by Mössbauer spectroscopy). The empirical formula calculated on the basis of 17 oxygens is Ca0.02Pb0.01Zn1.68Al0.60P3.09As0.01O17.00H5.15. The crystal structure was solved by direct methods and refined to an R1 index of 6.41% for 1332 observed reflections from single-crystal X-ray diffraction data (Mo-Kα radiation, CCD area detector). The structure of plimerite is isotypic with that of rockbridgeite and is based on face-sharing trimers of (Mϕ6) octahedra which link by sharing edges to form chains, that extend in the b-direction. Chains link to clusters comprising pairs of corner-sharing (Mϕ6) octahedra that link to PO4 tetrahedra forming sheets parallel to (001). The sheets link via octahedra and tetrahedra corners into a heteropolyhedral framework structure. The mineral name honours Professor Ian Plimer for his contributions to the study of the geology of ore deposits.

During an investigation of the phase equilibria in the ternary system Ni/P/Sn, the existence of a new phase Ni21Sn2P6 with a composition close to the known Ni10P3Sn phase was found. The crystal structure of the new phase was determined using single crystal X-ray diffraction. The structure was solved employing Patterson and Difference Fourier Analysis. Ni21P6Sn2 (space group , a = 1112.2 pm) crystallizes in an ordered variant of the C6Cr23 structure common to many carbides, borides and phosphides. The relation between Ni21Sn2P6 and other C6Cr23 type phases and to Ni10P3Sn was established.

An Al-rich tourmaline from the Sahatany Pegmatite Field at Manjaka, Sahatany Valley, Madagascar, was structurally and chemically characterized. The combination of chemical and structural data yields an optimized formula of X (Na0.53Ca0.09□0.38) Y (Al2.00Li0.90Mn2+0.09Fe2+ 0.01) Z Al6 (BO3)3 T [Si5.61B0.39]O18 V (OH)3 W [(OH)0.6O0.4], with a = 15.777(1), c = 7.086(1) A ( R 1 = 0.017 for 3241 reflections). The 〈 T –O〉 distance of ~ 1.611 A is one of the smallest distances observed in natural tourmalines. The very short 〈 Y –O〉 distance of ~ 1.976 A reflects the relatively high amount of Al at the Y site. Together with other natural and synthetic Al-rich tourmalines, a very good inverse correlation ( r 2 = 0.996) between [4]B and the unit-cell volume was found. [4]B increases with the Al content at the Y site approximately as a power function with a linear term up until [4]B ≈ Si ≈ 3 apfu and Y Al ≈ 3 apfu, respectively, in natural and synthetic Al-rich tourmalines. Short-range order considerations would not allow for [4]B in solid solution between schorl and elbaite, but would in solid solutions between schorl, “oxy-schorl”, elbaite, liddicoatite, or rossmanite and hypothetical [4]B-rich tourmaline end-members with only Al3+ at the Y site. By plotting the [4]B content of synthetic and natural Al-rich tourmalines, which crystallized at elevated PT conditions, it is obvious that there are pronounced correlations between PT conditions and the [4]B content. Towards lower temperatures higher [4]B contents are found in tourmaline, which is consistent with previous investigations on the coordination of B in melts. Above a pressure of ~ 1000–1500 MPa (depending on the temperature) the highest observed [4]B content does not change significantly at a given temperature. The PT conditions of the formation of [4]B-rich olenite from Koralpe, Eastern Alps, Austria, can be estimated as 500–700 MPa/630 °C.

Phase relations in the ternary system Ce–Pt–Si have been established for the isothermal section at 800 °C based on X-ray powder diffraction, metallography, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) techniques on about 120 alloys, which were prepared by various methods employing arc-melting under argon or powder reaction sintering. Nineteen ternary compounds were observed. Atom order in the crystal structures of τ18-Ce5(Pt,Si)4 (Pnma; a=0.77223(3) nm, b=1.53279(8) nm c=0.80054(5) nm), τ3-Ce2Pt7Si4 (Pnma; a=1.96335(8) nm, b=0.40361(4) nm, c=1.12240(6) nm) and τ10-CePtSi2 (Cmcm; a=0.42943(2) nm, b=1.67357(5) nm, c=0.42372(2) nm) was determined by direct methods from X-ray single-crystal CCD data and found to be isotypic with the Sm5Ge4-type, the Ce2Pt7Ge4-type and the CeNiSi2-type, respectively. Rietveld refinements established the atom arrangement in the structures of Pt3Si (Pt3Ge-type, C2/m, a=0.7724(2) nm, b=0.7767(2) nm, c=0.5390(2) nm, β=133.86(2)°), τ16-Ce3Pt5Si (Ce3Pd5Si-type, Imma, a=0.74025(8) nm, b=1.2951(2) nm, c=0.7508(1) nm) and τ17-Ce3PtSi3 (Ba3Al2Ge2-type, Immm, a=0.41065(5) nm, b=0.43221(5) nm, c=1.8375(3) nm). Phase equilibria in Ce–Pt–Si are characterised by the absence of cerium solubility in platinum silicides. Cerium silicides and cerium platinides, however, dissolve significant amounts of the third component, whereby random substitution of the almost equally sized atom species platinum and silicon is reflected in extended homogeneous regions at constant Ce content such as for τ13-Ce(PtxSi1−x)2, τ6-Ce2Pt3+xSi5−x or τ7-CePt2−xSi2+x.

9-Bromo-7,12-dihydroindolo[3,2-d][1]benzazepin-6-ylhydrazine was reacted with 2-acetylpyridine to give a Schiff base as a potential tridentate ligand. The reaction of this ligand with gallium chloride afforded complexes of 1:1 and 2:1 stoichiometry. The results of X-ray diffraction studies of the ligand and both gallium complexes are reported and compared with the data for a related gallium complex with a Schiff base obtained from 9-bromo-7,12-dihydroindolo[3,2-d][1]benzazepin-6-ylhydrazine and 2-hydroxybenzaldehyde.

Mg(NO3)2, Co(NO3)2 and Ni(NO3)2 were obtained as tiny crystals by dehydration of melts of the respective hydrates in the range 410–450 K. Structure determinations and refinements are based on single crystal X-ray data (CCD area detector) measured at 120–370 K. Crystal parameters at 120 K: Mg(NO3)2: R−3, a = 10.474(1), c = 38.782(4) Å, Z = 36, R 1 = 0.028; Co(NO3)2: R−3, a = 10.445(1), c = 12.769(2) Å, Z = 12, R 1 = 0.019; Ni(NO3)2: R−3, a = 10.332(1), c = 12.658(2) Å, Z = 12, R 1 = 0.025. Co(NO3)2 and Ni(NO3)2 are isotypic; the structure of Mg(NO3)2 is closely related, although it is not simply a stacking variant – it forms a new structure type. In all three compounds the MO6 octahedra share all corners with the NO3 groups to form framework structures; any edge sharing is thereby avoided. The geometries of the structures are also discussed in relation to a simple theoretical cubic structure (space group Pa−3) with the same connection pattern of the MO6 and NO3 building units. Neither X-ray single crystal and powder work nor differential thermoanalytical investigations indicated polymorphism in the temperature range investigated.

The crystal structure of the ternary Laves phase ZrTiCu 2 with unusual stoichiometry has been determined from combined refinement of X-ray powder, X-ray single crystal and neutron powder intensity data. The derived structure is of type MgZn 2 (space group P 6 3 / mmc ) with lattice parameters a = 0.51491(3) nm, c = 0.82421(8) nm. Crystal symmetry and composition reveal a high degree of atomic disorder, because Ti and Zr atoms share the 4f sites, whereas Ti and Cu atoms are found at the 6h sites. The 2a sites, however, are exclusively occupied by Cu. Lattice parameters for alloys Zr 1− x Ti 1− x Cu 2+2 x (annealed at 800 °C) as a function of the concentration of Cu for a constant ratio of Zr/Ti = 1 vary in a nonlinear way, which is consistent with the described complex atomic substitution mechanism. At a load of 2 N the micro-hardness was measured to be 7.5 ± 0.3 GPa, which is significantly larger than for most of the binary Ti–Cu or Zr–Cu phases. By a density functional theory ab initio approach the site preferences of Zr, Ti and Cu were calculated indicating that a random mixture of Ti and Cu atoms at the 6h lattice sites is a key factor to stabilize the proposed structure, which is unique for a Laves phase. Lattice parameters, elastic constants and shear moduli for polycrystalline ZrTiCu 2 were also derived. The Vickers hardness of 6.2 GPa was estimated by applying a correlation between shear modulus and hardness. Data as calculated by the ab initio approach are in good agreement with the experimental findings.

A first series of enantiomerically pure helical oligo(formaldehyde)s (=oligo(oxymethylen)s) 16–20 was synthesized. To induce the chiral uniformity of the helices, we used (1S)-2,2-dimethyl-1-phenylpropan-1-ol (14) to generate the end groups at the α and ω terminus (Scheme 6). Propanol 14 was accessible from its racemate by acetal formation with lactol 12 and separation of the diastereoisomers (Scheme 5). The helicity of the oligomers was investigated by temperature-dependent CD, NMR, and optical-rotation studies. In addition to qualitative considerations concerning the helicity of oligo(formaldehyde)s, we performed calculations of the dimer 17 and the pentamer 20 as well as X-ray structure analyses of the dimer 17 and the tetramer 19 to establish the handedness of the helices and to correlate their sense with the absolute configuration of the inducing stereogenic center. The results may be of relevance with respect to induction and propagation of chirality in prebiotic chemistry.