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Title: Extrinsic Curie temperature and spin reorientation changes in Nd{sub 2}Fe{sub 14}B/{alpha}-Fe nanocomposites

Abstract

The Curie temperatures and spin reorientation temperatures of a series of four melt-spun nanocomposite materials comprised of Nd{sub 2}Fe{sub 1}4B and varying amounts of {alpha}-Fe were measured using independent techniques. The phase constitution and grain size was assessed with synchrotron x-ray diffraction; the Curie temperatures were measured by differential thermal analysis (DTA) and dc SQUID magnetometry in the temperature range 375 K {le} T {le} 800 K, whereas the spin reorientation transition temperature was determined from ac susceptibility measurements taken in the range 10 K {le} T {le} 300 K. The Curie temperature increases with increasing excess iron content, resulting in a 18 {degree} enhancement over the Curie temperature of pure Nd{sub 2}Fe{sub 14}B for 27 wt% excess {alpha}-Fe. The spin reorientation temperatures are depressed from the single-crystal value by an average of 10 degrees. Both anomalous effects are attributed to intergranular exchange coupling present in the alloys, although the effects of uncompensated stress between the constituent phases cannot be ruled out The experimental results suggest that while the Curie temperature of the Nd{sub 2}Fe{sub 14}B phase may be extrinsically enhanced significantly beyond the bulk value, possibly extending the range of applications of this compound, the anisotropy may be simultaneouslymore » lowered, impeding the attainment of high coercivities in these alloys.« less

Authors:
 [1];  [2]
  1. Brookhaven National Lab., Upton, NY (United States)
  2. Magnequench International, Inc., Anderson, IN (United States)
Publication Date:
Research Org.:
Brookhaven National Lab., Neutral Particle Beam Div., Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Energy Research, Washington, DC (United States)
OSTI Identifier:
672116
Report Number(s):
BNL-65211; CONF-980802-
ON: DE98005715; BR: KC020205; TRN: 99:000836
DOE Contract Number:  
AC02-98CH10886
Resource Type:
Technical Report
Resource Relation:
Conference: 15. international workshop on rare-earth magnets and their applications and 10th international symposium on magnetic anisotropy and coercivity in rare-earth transition metal alloys, Dresden (Germany), 30 Aug - 4 Sep 1998; Other Information: PBD: May 1998
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; MAGNETIC PROPERTIES; NEODYMIUM ALLOYS; IRON ALLOYS; BORON ALLOYS; IRON; COMPOSITE MATERIALS; CURIE POINT; SPIN ORIENTATION; STOICHIOMETRY; EXPERIMENTAL DATA

Citation Formats

Lewis, L H, and Panchanathan, V. Extrinsic Curie temperature and spin reorientation changes in Nd{sub 2}Fe{sub 14}B/{alpha}-Fe nanocomposites. United States: N. p., 1998. Web. doi:10.2172/672116.
Lewis, L H, & Panchanathan, V. Extrinsic Curie temperature and spin reorientation changes in Nd{sub 2}Fe{sub 14}B/{alpha}-Fe nanocomposites. United States. https://doi.org/10.2172/672116
Lewis, L H, and Panchanathan, V. 1998. "Extrinsic Curie temperature and spin reorientation changes in Nd{sub 2}Fe{sub 14}B/{alpha}-Fe nanocomposites". United States. https://doi.org/10.2172/672116. https://www.osti.gov/servlets/purl/672116.
@article{osti_672116,
title = {Extrinsic Curie temperature and spin reorientation changes in Nd{sub 2}Fe{sub 14}B/{alpha}-Fe nanocomposites},
author = {Lewis, L H and Panchanathan, V},
abstractNote = {The Curie temperatures and spin reorientation temperatures of a series of four melt-spun nanocomposite materials comprised of Nd{sub 2}Fe{sub 1}4B and varying amounts of {alpha}-Fe were measured using independent techniques. The phase constitution and grain size was assessed with synchrotron x-ray diffraction; the Curie temperatures were measured by differential thermal analysis (DTA) and dc SQUID magnetometry in the temperature range 375 K {le} T {le} 800 K, whereas the spin reorientation transition temperature was determined from ac susceptibility measurements taken in the range 10 K {le} T {le} 300 K. The Curie temperature increases with increasing excess iron content, resulting in a 18 {degree} enhancement over the Curie temperature of pure Nd{sub 2}Fe{sub 14}B for 27 wt% excess {alpha}-Fe. The spin reorientation temperatures are depressed from the single-crystal value by an average of 10 degrees. Both anomalous effects are attributed to intergranular exchange coupling present in the alloys, although the effects of uncompensated stress between the constituent phases cannot be ruled out The experimental results suggest that while the Curie temperature of the Nd{sub 2}Fe{sub 14}B phase may be extrinsically enhanced significantly beyond the bulk value, possibly extending the range of applications of this compound, the anisotropy may be simultaneously lowered, impeding the attainment of high coercivities in these alloys.},
doi = {10.2172/672116},
url = {https://www.osti.gov/biblio/672116}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri May 01 00:00:00 EDT 1998},
month = {Fri May 01 00:00:00 EDT 1998}
}