Phase relations and structural features in the system Ni-Zn-B
- Department of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Vienna (Austria)
- Institute of Mineralogy and Crystallography, University of Vienna, Althanstrasse 14, A-1090 Vienna (Austria)
- Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Zizkova 22, 61662 Brno (Czech Republic)
Phase relations for the system Ni-Zn-B have been established in the isothermal section at 800 Degree-Sign 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 Ni{sub x}B{sub y} and Zn-filings. Six ternary compounds (labeled {tau}{sub 1} to {tau}{sub 6}) 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 {tau}-phase {tau}{sub 1}-(Ni{sub 1-x}Zn{sub x}){sub 21}[Zn{sub 1-y-z}{open_square}{sub y}(B{sub 4}){sub z}]{sub 2}B{sub 6} (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 Cr{sub 23}C{sub 6} type with space group Fm3{sup Macron }m, but revealed partial replacement of Zn-atoms by B{sub 4}-tetrahedra (R{sub F}=0.014). Whereas Ni/Zn exchange (at constant B-content) ranges at about 4-5 at% for {tau}{sub 4}-Ni{sub 3}ZnB{sub 2} and {tau}{sub 5}-Ni{sub 48}Zn{sub 32}B{sub 20}, it is below 3 at% for {tau}{sub 2}-Ni{sub 12}ZnB{sub 8-x} (x=0.43), {tau}{sub 3}-Ni{sub 21}Zn{sub 2}B{sub 20} and {tau}{sub 6}-Ni{sub 47}Zn{sub 23}B{sub 30}. The crystal structures of {tau}{sub 2}-Ni{sub 12}ZnB{sub 8-x} (x=0.43; Ni{sub 12}AlB{sub 8} type), {tau}{sub 3}-Ni{sub 21}Zn{sub 2}B{sub 20} (own type) and {tau}{sub 4}-Ni{sub 3}ZnB{sub 2} (own type) have been determined in our foregoing paper [8]. Due to the non-availability of suitable single crystals, the crystal structures of {tau}{sub 5}-Ni{sub 48}Zn{sub 32}B{sub 20} (body-centered orthorhombic; a=1.6(2) nm, b=0.63(7) nm, and c=0.27(0) nm, determined from TEM) and of {tau}{sub 6}-Ni{sub 47}Zn{sub 23}B{sub 30} have not been elucidated yet. Phase equilibria at 800 Degree-Sign C are dominated by a large three-phase field ({beta}B)+Ni{sub 2}Zn{sub 11}+{tau}{sub 3}, 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-Ni{sub 4}B{sub 3-x} (x=0.19; Pnma, a=1.9665(4) nm, b=0.29852(1) nm, c=0.65750(2) nm; R{sub F}=0.015) and m-Ni{sub 4}B{sub 3} (C2/c, a=0.64356(3) nm, b=0.48867(3) nm, c=0.78267(3) nm, {beta}=103.288(3) Degree-Sign , R{sub F}=0.021). - Graphical abstract: Ni-Zn-B isothermal section at 800 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer Phase relations were determined for the system Ni-Zn-B at 800 Degree-Sign C. Black-Right-Pointing-Pointer Existence of six ternary compounds ({tau}{sub 1}-{tau}{sub 6}) has been confirmed at 800 Degree-Sign C. Black-Right-Pointing-Pointer Homogeneity range for {tau}{sub 1} with respect to Ni/Zn and Zn/B at 800 Degree-Sign C has been determined. Black-Right-Pointing-Pointer The crystal structures of {tau}{sub 5}-Ni{sub 48}Zn{sub 32}B{sub 20} from TEM (oI, a=1.6(2) nm, b=0.63(7) nm, and c=0.27(0) nm). Black-Right-Pointing-Pointer Precise data on {tau}{sub 1}-(Ni{sub 1-x}Zn{sub x}){sub 21}[Zn{sub 1-y-z{open_square}y}(B{sub 4}){sub z}]{sub 2}B{sub 6} (0.07{<=}x{<=}0.11, 0.07{<=}y{<=}0.53, 0{<=}z{<=}0.3), o-Ni{sub 4}B{sub 3-x} and m-Ni{sub 4}B{sub 3} have been presented.
- OSTI ID:
- 22150012
- Journal Information:
- Journal of Solid State Chemistry, Vol. 198; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
Similar Records
Synthesis, structures and properties of the new lithium cobalt(II) phosphate Li{sub 4}Co(PO{sub 4}){sub 2}
Rare-earth chromium gallides RE{sub 4}CrGa{sub 12} (RE=Tb-Tm)