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Title: Preparation and properties of a new ternary phase Mg{sub 3+x}Ni{sub 7−x}B{sub 2} (0.17≤x≤0.66) and its Cu-doping effect

In recent years, the materials in the B–Mg–Ni system have been intensively studied due to their excellent properties of hydrogen storage and superconductivity. Solving the crystal structure of phases in this system will facilitate an understanding of the mechanism of their physical properties. In this study, we report the preparation, crystal structure and physical properties of a new ternary phase Mg{sub 3+x}Ni{sub 7−x}B{sub 2} in the B–Mg–Ni system. The Mg{sub 3+x}Ni{sub 7−x}B{sub 2} phase was prepared by solid-state reactions at 1073 K and its crystal structure was determined and refined using X-ray powder diffraction data. The Mg{sub 3+x}Ni{sub 7−x}B{sub 2} phase crystallizes in the Ca{sub 3}Ni{sub 7}B{sub 2} structure type (space group R-3m, no. 166) with a=4.9496(3)–5.0105(6) Å, c=20.480(1)–20.581(1) Å depending on the x value, where x varies from 0.17 to 0.66. Two samples with nominal compositions Mg{sub 10}Ni{sub 20}B{sub 6} and Mg{sub 12}Ni{sub 18}B{sub 6} were characterized by magnetization and electric resistivity measurements in the temperature range from 5 K to room temperature. Both samples exhibited metallic behavior and showed spin-glass-like behavior with a spin freezing temperature (T{sub f}) around 33 K. A study of the Cu-doping effect showed that limited Cu content can be doped into the Mg{submore » 3+x}Ni{sub 7−x}B{sub 2} compound and T{sub f} decreases as the Cu content increases. - Graphical abstract: The crystal structure of the Mg{sub 3+x}Ni{sub 7−x}B{sub 2} phase. - Highlights: • The crystal structure and solid solution range of Mg{sub 3+x}Ni{sub 7−x}B{sub 2} were revealed. • The magnetization and electrical resistivity of Mg{sub 3+x}Ni{sub 7−x}B{sub 2} were studied. • The Cu-doping effect of Mg{sub 3+x}Ni{sub 7−x}B{sub 2} was investigated.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [4] ;  [5] ;  [1] ;  [2] ;  [1] ;  [2] ;  [1]
  1. Institute of Physics, Chinese Academy of Sciences, Beijing National Laboratory for Condensed Matter Physics, Beijing 100190 (China)
  2. (China)
  3. (Hong Kong)
  4. Department of Civil Engineering, The University of Hong Kong, Hong Kong SAR (Hong Kong)
  5. Key Laboratory of Nonferrous Metals and New Processing Technology of Materials, Ministry of Education, Guangxi University, Nanning, Guangxi 530004 (China)
Publication Date:
OSTI Identifier:
22475632
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 226; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; BORON ALLOYS; CONCENTRATION RATIO; CRYSTAL STRUCTURE; DOPED MATERIALS; FREEZING; HYDROGEN STORAGE; MAGNESIUM ALLOYS; MAGNETIZATION; NICKEL BASE ALLOYS; SOLID SOLUTIONS; SOLIDS; SPIN GLASS STATE; SUPERCONDUCTIVITY; TEMPERATURE RANGE 0273-0400 K; TERNARY ALLOY SYSTEMS; X-RAY DIFFRACTION