skip to main content

Title: Giant negative thermal expansion covering room temperature in nanocrystalline GaN{sub x}Mn{sub 3}

Nanocrystalline antiperovskite GaN{sub x}Mn{sub 3} powders were prepared by mechanically milling. The micrograin GaN{sub x}Mn{sub 3} exhibits an abrupt volume contraction at the antiferromagnetic (AFM) to paramagnetic (PM) (AFM-PM) transition. The temperature window of volume contraction (ΔT) is broadened to 50 K as the average grain size (〈D〉) is reduced to ∼30 nm. The corresponding coefficient of linear thermal expansion (α) reaches ∼ −70 ppm/K, which are comparable to those of giant NTE materials. Further reducing 〈D〉 to ∼10 nm, ΔT exceeds 100 K and α remains as large as −30 ppm/K (−21 ppm/K) for x = 1.0 (x = 0.9). Excess atomic displacements together with the reduced structural coherence, revealed by high-energy X-ray pair distribution functions, are suggested to delay the AFM-PM transition. By controlling 〈D〉, giant NTE may also be achievable in other materials with large lattice contraction due to electronic or magnetic phase transitions.
Authors:
; ; ; ; ; ; ; ;  [1] ; ;  [2] ; ;  [3] ;  [4] ;  [5] ;  [5]
  1. Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China)
  2. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 200120 (China)
  3. Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026 (China)
  4. High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031 (China)
  5. (China)
Publication Date:
OSTI Identifier:
22482164
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 13; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANTIFERROMAGNETISM; ATOMIC DISPLACEMENTS; CONTRACTION; CRYSTALS; DISTRIBUTION FUNCTIONS; GALLIUM NITRIDES; GRAIN SIZE; MILLING; NANOSTRUCTURES; PARAMAGNETISM; PHASE TRANSFORMATIONS; POWDERS; TEMPERATURE RANGE 0273-0400 K; THERMAL EXPANSION; X RADIATION