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The four ternary arsenides ATt3As3 (A=K, Rb; Tt=Ge, Sn) were obtained by reaction of the elements at 600–650 °C. They adopt an orthorhombic structure (space group Pnma, Z=4, with cell parameters ranging from a=9.9931(11) A, b=3.7664(4) A, c=18.607(2) A for KGe3As3 to a=10.3211(11) A, b=4.0917(4) A, c=19.570(2) A for RbSn3As3) containing corrugated [Tt3As3] layers built from Tt-centred trigonal pyramids and tetrahedra forming five-membered rings decorated with As handles. They can be considered to be Zintl phases with Tt atoms in +4, +3, and +1 oxidation states. Band structure calculations predict that these compounds are semiconductors with narrow band gaps (0.71 eV in KGe3As3, 0.50 eV in KSn3As3).

The new ternary arsenides AE3TrAs3 (AE = Sr, Ba; Tr = Al, Ga) and their phosphide analogs Sr3GaP3 and Ba3AlP3 have been prepared by reactions of the respective elements at high temperatures. Single-crystal X-ray diffraction studies reveal that Sr3AlAs3 and Ba3AlAs3 adopt the Ba3AlSb3-type structure (Pearson symbol oC56, space group Cmce, Z = 8). This structure is also realized for Sr3GaP3 and Ba3AlP3. The compounds Sr3GaAs3 and Ba3GaAs3 crystallize with the Ba3GaSb3-type structure (Pearson symbol oP56, space group Pnma, Z = 8). Both structures are made up of isolated pairs of edge-shared AlPn4 and GaPn4 tetrahedra (Pn = pnictogen, i.e., P or As), separated by the alkaline-earth Sr2+ and Ba2+ cations. In both cases, there are no homoatomic bonds, hence, regardless of the slightly different atomic arrangements, both structures can be rationalized as valence-precise [AE2+]3[Tr3+][Pn3−]3, or rather [AE2+]6[Tr2Pn6]12−, i.e., as Zintl phases.

Crystal structure of the new ternary antimonide Y 3 Ni 6 Sb 5 was investigated using X-ray single crystal data: own type of structure, space group P 2 1 / m , a = 1.06358(6) nm, b = 0.42030(3) nm, c = 1.26520(9), β = 113.326(3)°, Z = 2, R F = 0.055, wR F = 0.063 for 1341 independent reflections and 98 variable parameters. Isotypic compounds Gd 3 Ni 6 Sb 5 and Tb 3 Ni 6 Sb 5 were synthesized. Magnetic and electric transport properties were studied in the temperature range above 5 K. Y 3 Ni 6 Sb 5 is a temperature independent Pauli type paramagnet. The Gd 3 Ni 6 Sb 5 compound orders ferromagnetically at T C = 8 K, whereas the Tb 3 Ni 6 Sb 5 homologue is an antiferromagnet at T N –5 K. The onset of magnetic ordering is also proved by the electrical resistivity measurements. The analysis of the resistivity, ρ ( T ), measurements for Y 3 Ni 6 Sb 5 resulted in a Debye temperature Θ D = 135 K.

The ternary pnictides Rb4Zn7As7 and Rb7Mn12Sb12 and their quaternary derivatives Rb4Mn3.5Zn3.5Sb7 and Rb7Mn4Cd8Sb12 have been prepared by reactions of the elements at 600 °C. They crystallize in two new structure types: orthorhombic Rb4Zn7As7-type (space group Cmcm, Z = 4; a = 4.1883(4) A, b = 24.844(2) A, c = 17.6056(17) A for Rb4Zn7As7; a = 4.3911(8) A, b = 26.546(5) A, c = 18.743(4) A for Rb4Mn3.5Zn3.5Sb7) and monoclinic Rb7Mn12Sb12-type (space group C2/m, Z = 2; a = 26.544(12) A, b = 4.448(2) A, c = 16.676(8) A, β = 103.183(8)° for Rb7Mn12Sb12; a = 27.009(4) A, b = 4.5752(7) A, c = 16.727(3) A, β = 103.221(2)° for Rb7Mn4Cd8Sb12). These related structures contain corrugated anionic layers built up by connecting ribbons of edge-sharing tetrahedra in a zigzag-like manner with chains of Mn-centered square pyramids located at the hinges. Homoatomic pnicogen–pnicogen bonding occurs in the form of Pn2 pairs. The compounds are formally deficient by one electron per formula unit, as confirmed by band structure...

Dirubidium pentacadmium tetraarsenide, Rb2Cd5As4, dirubidium pentazinc tetraantimonide, Rb2Zn5Sb4, and the solid-solution phase dirubidium pentacadmium tetra(arsenide/antimonide), Rb2Cd5(As,Sb)4[or Rb2Cd5As3.00(1)Sb1.00(1)], have been prepared by direct reaction of the component elements at high temperature. These compounds are charge-balanced Zintl phases and adopt the orthorhombic K2Zn5As4-type structure (Pearson symboloC44), featuring a three-dimensional [M5Pn4]2−framework [M= Zn or Cd;Pnis a pnicogen or Group 15 (Group V) element] built of linkedMPn4tetrahedra, and large channels extending along thebaxis which host Rb+cations. The As and Sb atoms in Rb2Cd5(As,Sb)4are randomly disordered over the two available pnicogen sites. Band-structure calculations predict that Rb2Cd5As4is a small-band-gap semiconductor and Rb2Zn5Sb4is a semimetal.

The ternary rare-earth zinc arsenides RE Zn 2 As 3 ( RE =La–Pr) have been prepared by reactions of the elements at 800 °C. They adopt new tetragonal structure types, with the La member (space group I 4/ mmm , Z =4, a =4.1133(2) A, c =32.1246(14) A) differing from the Ce and Pr members (space group P 4/ nmm , Z =2, a =4.0804(6)–4.0534(12) A, c =16.089(5)–16.059(10) A, respectively) in the disposition of RE -centred square antiprisms on opposite sides of square As nets. The structures contain thick anionic slabs, built from edge-sharing ZnAs 4 tetrahedra, that can be considered either as stackings of three PbO-type layers or as fragments of the fluorite-type structure. These slabs are deficient in Zn and are reminiscent of the same features in binary arsenide Zn 3 As 2 . LaZn 2 As 3 exhibits temperature-independent paramagnetism whereas CeZn 2 As 3 follows modified Curie–Weiss behavior consistent with Ce 3+ species but with no occurrence of long-range ordering.

Construction of the isothermal section in the metal-rich portion (67 atom % P) of the Mo-Fe-P phase diagram at 800 °C has led to the identification of two new ternary phases: (Mo(1-x)Fe(x))(2)P (x = 0.30-0.82) and (Mo(1-x)Fe(x))(3)P (x = 0.10-0.15). The occurrence of a Co(2)Si-type ternary phase (Mo(1-x)Fe(x))(2)P, which straddles the equiatomic composition MoFeP, is common to other ternary transition-metal phosphide systems. However, the ternary phase (Mo(1-x)Fe(x))(3)P is unusual because it is distinct from the binary phase Mo(3)P, notwithstanding their similar compositions and structures. The relationship has been clarified through single-crystal X-ray diffraction studies on Mo(3)P (α-V(3)S-type, space group I42m, a = 9.7925(11) Å, c = 4.8246(6) Å) and (Mo(0.85)Fe(0.15))(3)P (Ni(3)P-type, space group I4, a = 9.6982(8) Å, c = 4.7590(4) Å) at -100 °C. Representation in terms of nets containing fused triangles provides a pathway to transform these closely related structures through twisting. Band structure calculations support the adoption of these structure types and the site preference of Fe atoms. Electrical resistivity measurements on (Mo(0.85)Fe(0.15))(3)P reveal metallic behavior but no superconducting transition.

The four ternary arsenides ATt3As3 (A=K, Rb; Tt=Ge, Sn) were obtained by reaction of the elements at 600–650 °C. They adopt an orthorhombic structure (space group Pnma, Z=4, with cell parameters ranging from a=9.9931(11) A, b=3.7664(4) A, c=18.607(2) A for KGe3As3 to a=10.3211(11) A, b=4.0917(4) A, c=19.570(2) A for RbSn3As3) containing corrugated [Tt3As3] layers built from Tt-centred trigonal pyramids and tetrahedra forming five-membered rings decorated with As handles. They can be considered to be Zintl phases with Tt atoms in +4, +3, and +1 oxidation states. Band structure calculations predict that these compounds are semiconductors with narrow band gaps (0.71 eV in KGe3As3, 0.50 eV in KSn3As3).

The ternary rare-earth-metal chromium gallides RE 4 CrGa 12 ( RE =Tb–Tm) have been prepared by reactions of the elements at 1000 °C in the presence of excess gallium used as a self-flux. Their structures are derived by inserting Cr atoms into a quarter of the empty Ga 6 octahedral clusters found in the parent binary gallides RE Ga 3 (AuCu 3 -type), although single-crystal X-ray diffraction studies suggest that complex superstructures may be adopted. An ideal ordered Y 4 PdGa 12 -type structure was successfully refined for a crystal of Dy 4 CrGa 12 (Pearson symbol cI 34, space group Im 3 ¯ m , Z =2, a =8.572(1) A). Magnetic measurements on single-crystal samples reveal ferromagnetic or possibly ferrimagnetic ordering for the Tb, Dy, and Er members ( T C =22, 15, and 2.8 K, respectively) and antiferromagnetic ordering for the Ho member ( T N =7.5 K). Band structure calculations on a hypothetical “Y 4 CrGa 12 ” model suggest that the Cr atoms carry no local magnetic moment.

Four ternary pnictides AAg{sub 4}Pn{sub 2} (A=Sr, Eu; Pn=As, Sb) were prepared by reactions of the elements at 850 Degree-Sign C and their crystal structures were determined from single-crystal X-ray diffraction studies. These silver-containing pnictides AAg{sub 4}Pn{sub 2} adopt the trigonal CaCu{sub 4}P{sub 2}-type structure (Pearson symbol hR21, space group R3-bar m, Z=3; a=4.5555(6) A, c=24.041(3) A for SrAg{sub 4}As{sub 2}; a=4.5352(2) A, c=23.7221(11) A for EuAg{sub 4}As{sub 2}; a=4.7404(4) A, c=25.029(2) A for SrAg{sub 4}Sb{sub 2}; a=4.7239(3) A, c=24.689(2) A for EuAg{sub 4}Sb{sub 2}), which can be derived from the trigonal CaAl{sub 2}Si{sub 2}-type structure of the isoelectronic zinc-containing pnictides AZn{sub 2}Pn{sub 2} by insertion of additional Ag atoms into trigonal planar sites within [M{sub 2}Pn{sub 2}]{sup 2-} slabs built up of edge-sharing tetrahedra. Band structure calculations on SrAg{sub 4}As{sub 2} and SrAg{sub 4}Sb{sub 2} revealed that these charge-balanced Zintl phases actually exhibit no gap at the Fermi level and are predicted to be semimetals. - Graphical abstract: SrAg{sub 4}As{sub 2} and related pnictides adopt a CaCu{sub 4}P{sub 2}-type structure in which additional Ag atoms enter trigonal planar sites within slabs built from edge-sharing tetrahedra. Highlights: Black-Right-Pointing-Pointer AAg{sub 4}Pn{sub 2} are the first Ag-containing members of the CaCu{sub 4}P{submore » 2}-type structure. Black-Right-Pointing-Pointer Ag atoms are stuffed in trigonal planar sites within CaAl{sub 2}Si{sub 2}-type slabs. Black-Right-Pointing-Pointer Ag-Ag bonding develops through attractive d{sup 10}-d{sup 10} interactions.« less

The ternary arsenides A(2)Zn(2)As(3) and the quaternary derivatives A(2)Ag(2)ZnAs(3) (A = Sr, Eu) have been prepared by stoichiometric reaction of the elements at 800 °C. Compounds A(2)Zn(2)As(3) crystallize with the monoclinic Ba(2)Cd(2)Sb(3)-type structure (Pearson symbol mC28, space group C2/m, Z = 4; a = 16.212(5) Å, b = 4.275(1) Å, c = 11.955(3) Å, β = 126.271(3)° for Sr(2)Zn(2)As(3); a = 16.032(4) Å, b = 4.255(1) Å, c = 11.871(3) Å, β = 126.525(3)° for Eu(2)Zn(2)As(3)) in which CaAl(2)Si(2)-type fragments, built up of edge-sharing Zn-centered tetrahedra, are interconnected by homoatomic As-As bonds to form anionic slabs [Zn(2)As(3)](4-) separated by A(2+) cations. Compounds A(2)Ag(2)ZnAs(3) crystallize with the monoclinic Yb(2)Zn(3)Ge(3)-type structure (Pearson symbol mC32, space group C2/m; a = 16.759(2) Å, b = 4.4689(5) Å, c = 12.202(1) Å, β = 127.058(1)° for Sr(2)Ag(2)ZnAs(3); a = 16.427(1) Å, b = 4.4721(3) Å, c = 11.9613(7) Å, β = 126.205(1)° for Eu(2)Ag(2)ZnAs(3)), which can be regarded as a stuffed derivative of the Ba(2)Cd(2)Sb(3)-type structure with additional transition-metal atoms in tetrahedral coordination inserted to link the anionic slabs together. The Ag and Zn atoms undergo disorder but with preferential occupancy over four sites centered in either tetrahedral or trigonal planar geometry. The site distribution of these metal atoms depends on a complex interplay of size and electronic factors. All compounds are Zintl phases. Band structure calculations predict that Sr(2)Zn(2)As(3) is a narrow band gap semiconductor and Sr(2)Ag(2)ZnAs(3) is a semimetal. Electrical resistivity measurements revealed band gaps of 0.04 eV for Sr(2)Zn(2)As(3) and 0.02 eV for Eu(2)Zn(2)As(3), the latter undergoing an apparent metal-to-semiconductor transition at 25 K.

The ternary rare-earth zinc arsenides RE Zn 1− x As 2 ( RE =La–Nd, Sm) were prepared by reaction of the elements at 800 °C. Single-crystal and powder X-ray diffraction analysis revealed a defect SrZnBi 2 -type average structure for the La member (Pearson symbol tI 16, space group I 4/ mmm , Z =4; a =4.0770(9) A, c =20.533(5) A), in contrast to defect HfCuSi 2 -type average structures for the remaining RE members (Pearson symbol tP 8, space group P 4/ nmm , Z =2; a =4.0298(5)–3.9520(4) A, c =10.222(1)–10.099(1) A in the progression from Ce to Sm). The homogeneity range is not appreciable (estimated to be narrower than 0.6 x 1− x As 2 ) and the formula RE Zn 0.67 As 2 likely represents the Zn-rich phase boundary. The Ce–Nd members are Curie–Weiss paramagnets. LaZn 0.67 As 2 shows activated behavior in its electrical resistivity, whereas SmZn 0.67 As 2 exhibits anomalies in its temperature dependence of the electrical resistivity.

Ternary rare-earth cobalt gallides RE4Co3Ga16 (RE = Gd–Er, Y) have been prepared by arc-melting of the elements followed by annealing at 800 °C. Single crystals of the Gd and Tb members were also grown in the presence of a Ga self-flux. They extend the rare-earth substitution possible in the Sm4Co3Ga16-type structure (Pearson symbol tP23, space group P4/mmm, Z = 1), in which additional Co atoms enter as self-interstitials into the parent RE2CoGa8 structure. Structural refinements were carried out on single-crystal (RE = Gd, Tb) and powder (RE = Dy, Ho, Er, Y) X-ray diffraction data. Cell parameters lie in the ranges of a = 6.03–5.96 A and c = 11.11–10.96 A. Magnetic measurements on RE4Co3Ga16 (RE = Gd, Tb, Dy) reveal that they order antiferromagnetically below TN of 19, 25, and 14 K, respectively; Y4Co3Ga16 is Pauli paramagnetic. The electrical resistivity of Tb4Co3Ga16 undergoes a transition coincident with the magnetic ordering temperature. Band structure calculations on Y4Co3Ga16 indicate that the major bonding contributions arise from Co–Ga and Ga–Ga interactions, with the stuffing of interstitial Co atoms into octahedral sites of the parent Y2CoGa8 structure, which provides additional Co–Ga bonding stabilization.

The rare-earth iron arsenides RE(12)Fe(57.5)As(41) (RE = La, Ce) have been prepared by direct reactions of the elements in the presence of a Sn flux. Analysis of single-crystal X-ray diffraction data reveals that they adopt a new orthorhombic structure type (Pearson symbol oP236, space group Pmmn, Z = 2; a = 10.8881(9) A, b = 25.753(2) A, c = 12.5436(10) A for RE = La; a = 10.8376(8) A, b = 25.639(2) A, c = 12.4701(9) A for RE = Ce). In this metal-rich arsenide, the complex three-dimensional network (derived from 4 RE, 24 Fe, and 17 As sites) can be described as being built from unusual wavelike layers of connected As-centered trigonal prisms. Five of the Fe sites are partially occupied. The electronic structure of these compounds was probed through core-line X-ray photoelectron spectra. Magnetic susceptibility measurements indicated ferromagnetic ordering at T(C) = 125 and 95 K for the La and Ce compounds, respectively. Electrical resistivity measurements on single crystals of Ce(12)Fe(57.5)As(41) showed metallic behavior with a prominent transition that coincides closely with the ferromagnetic ordering temperature.

A new ternary phosphide Y 6 Ni 15− x P 10+ y ( x =0.08, y =0.18) has been obtained in the Y–Ni–P system. Single crystals of this compound have been investigated on a Nonius KappaCCD X-ray diffractometer using Mo Kα radiation ( λ =0.071073 nm). The symmetry has been found to be hexagonal with space group P 6 3 / m and unit cell parameters a =1.6447(1) nm and c =0.37891(2) nm. Structure refinement including anisotropic displacement parameters led to the following results: R F =0.056 ( R w =0.047), GOF=1.060 for 558 reflections with F ( h k l ) > 4 σF ( h k l ). The ternary phosphide Y 6 Ni 15− x P 10+ y exhibits a new structure, which is derived from the Ce 6 Ni 15 P 10 and Nd 3 Ni 7 P 5 structure types.

The title compounds are prepared by arc melting of stoichiometric amounts of the elements followed by annealing (evacuated quartz tubes, 770 K, 720 h).

The title compounds are synthesized from stoichiometric mixtures of the elements (alumina crucibles, 600 °C, 10 d) and characterized by single crystal XRD and TB-LMTO-ASA band structure calculations.

Rb2Cd5As4 (I), Rb2Zn5Sb4 (II) and the solid solution Rb2Cd5(As,Sb)4 (III) are prepared by melting of the elements (Nb tubes in evacuated silica ampule; (I): 923 K, 7 d, ice quenching, (II): 823 K, 10 d, cooling rate 3 K/h).

The ternary rare-earth zinc arsenides RE Zn 2 As 3 ( RE =La–Pr) have been prepared by reactions of the elements at 800 °C. They adopt new tetragonal structure types, with the La member (space group I 4/ mmm , Z =4, a =4.1133(2) A, c =32.1246(14) A) differing from the Ce and Pr members (space group P 4/ nmm , Z =2, a =4.0804(6)–4.0534(12) A, c =16.089(5)–16.059(10) A, respectively) in the disposition of RE -centred square antiprisms on opposite sides of square As nets. The structures contain thick anionic slabs, built from edge-sharing ZnAs 4 tetrahedra, that can be considered either as stackings of three PbO-type layers or as fragments of the fluorite-type structure. These slabs are deficient in Zn and are reminiscent of the same features in binary arsenide Zn 3 As 2 . LaZn 2 As 3 exhibits temperature-independent paramagnetism whereas CeZn 2 As 3 follows modified Curie–Weiss behavior consistent with Ce 3+ species but with no occurrence of long-range ordering.

Two new ternary phases, (Mo1-xFex)2P (x = 0.30—0.82) and (Mo1-xFex)3P (x = 0.10—0.15) exist in the isothermal section of the title system at 800 °C.

The title compounds are prepared from stoichiometric mixtures of the elements (alumina crucible, 650 °C for K sample, 600 °C for Rb sample, 10 d) and characterized by single crystal XRD and TB-LMTO-ASA band structure calculations.

The new title compounds are prepared by reactions of stoichiometric mixtures of the elements (alumina crucible, 850 °C, 1—4 d) and characterized by single crystal XRD.

Stoichiometric reaction of the elements at high temperature yields the ternary arsenides K(2)Zn(5)As(4) (650 °C) and Rb(2)Zn(5)As(4) (600 °C). They adopt a new structure type (Pearson symbol oC44, space group Cmcm, Z = 4; a = 11.5758(5) Å, b = 7.0476(3) Å, c = 11.6352(5) Å for K(2)Zn(5)As(4); a = 11.6649(5) Å, b = 7.0953(3) Å, c = 11.7585(5) Å for Rb(2)Zn(5)As(4)) with a complex three-dimensional framework of linked ZnAs(4) tetrahedra generating large channels that are occupied by the alkali-metal cations. An alternative and useful way of describing the structure is through the use of stellae quadrangulae each consisting of four ZnAs(4) tetrahedra capping an empty central tetrahedron. These compounds are Zintl phases; band structure calculations on K(2)Zn(5)As(4) and Rb(2)Zn(5)As(4) indicate semiconducting behavior with a direct band gap of 0.4 eV.

The title compounds are prepared from stoichiometric mixtures of the elements (800 °C, 7 d) and characterized by single crystal XRD, electrical resistivity measurements, and TB-LMTO-ASA band structure calculations.

The compounds LnZn3As3 (Ln: La—Nd, Sm) with polymorphic modifications different from the previously known forms and the corresponding compounds LnCd3As3 (Ln: La—Pr) are prepared from the elements (800 °C, 7 d) and characterized by powder and single crystal XRD, electrical resistivity and magnetic measurements, and TB-LMTO computations.

The title compounds are prepared from the elements (800 °C, 336 h) and characterized by powder and single crystal XRD, magnetic susceptibility and electrical resistivity measurements, and TB-LMTO band structure calculations.

Ternary rare-earth zinc arsenides REZn(3)As(3) (RE = La-Nd, Sm) with polymorphic modifications different from the previously known defect CaAl(2)Si(2)-type forms, and the corresponding rare-earth cadmium arsenides RECd(3)As(3) (RE = La-Pr), have been prepared by reaction of the elements at 800 °C. LaZn(3)As(3) adopts a new orthorhombic structure type (Pearson symbol oP28, space group Pnma, Z = 4, a = 12.5935(8) Å, b = 4.1054(3) Å, c = 11.5968(7) Å) in which ZnAs(4) tetrahedra share edges to form ribbons that are fragments of other layered arsenide structures; these ribbons are then interconnected in a three-dimensional framework with large channels aligned parallel to the b direction that are occupied by La(3+) cations. All remaining compounds adopt the hexagonal ScAl(3)C(3)-type structure (Pearson symbol hP14, space group P6(3)/mmc, Z = 2; a = 4.1772(7)-4.1501(2) Å, c = 20.477(3)-20.357(1) Å for REZn(3)As(3) (RE = Ce, Pr, Nd, Sm); a = 4.4190(3)-4.3923(2) Å, c = 21.4407(13)-21.3004(8) Å for RECd(3)As(3) (RE = La-Pr)) in which [M(3)As(3)](3-) layers (M = Zn, Cd), formed by a triple stacking of nets of close-packed As atoms with M atoms occupying tetrahedral and trigonal planar sites, are separated by La(3+) cations. Electrical resistivity measurements and band structure calculations revealed that orthorhombic LaZn(3)As(3) is a narrow band gap semiconductor.

The rare-earth iron arsenides RE 12 Fe 57.5 As 41 (RE = La, Ce) have been prepared by direct reactions of the elements in the presence of a Sn flux. Analysis of single-crystal X-ray diffraction data reveals that they adopt a new orthorhombic structure type (Pearson symbol oP236, space group Pmmn, Z = 2; a = 10.8881(9) A, b = 25.753(2) A, c = 12.5436(10) A for RE = La; a = 10.8376(8) A, b = 25.639(2) A, c = 12.4701(9) A for RE = Ce). In this metal-rich arsenide, the complex three-dimensional network (derived from 4 RE, 24 Fe, and 17 As sites) can be described as being built from unusual wavelike layers of connected As-centered trigonal prisms. Five of the Fe sites are partially occupied. The electronic structure of these compounds was probed through core-line X-ray photoelectron spectra. Magnetic susceptibility measurements indicated ferromagnetic ordering at T c = 125 and 95 K for the La and Ce compounds, respectively. Electrical resistivity measurements on single crystals of Ce 12 Fe 57.5 As 41 showed metallic behavior with a prominent transition that coincides closely with the ferromagnetic ordering temperature.

A new ternary phosphide Y 6 Ni 15− x P 10+ y ( x =0.08, y =0.18) has been obtained in the Y–Ni–P system. Single crystals of this compound have been investigated on a Nonius KappaCCD X-ray diffractometer using Mo Kα radiation ( λ =0.071073 nm). The symmetry has been found to be hexagonal with space group P 6 3 / m and unit cell parameters a =1.6447(1) nm and c =0.37891(2) nm. Structure refinement including anisotropic displacement parameters led to the following results: R F =0.056 ( R w =0.047), GOF=1.060 for 558 reflections with F ( h k l ) > 4 σF ( h k l ). The ternary phosphide Y 6 Ni 15− x P 10+ y exhibits a new structure, which is derived from the Ce 6 Ni 15 P 10 and Nd 3 Ni 7 P 5 structure types.