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Title: Single-Crystal Permanent Magnets: Extraordinary Magnetic Behavior in the Ta-,Cu-, and Fe-Substituted CeCo 5 Systems

Abstract

To reduce material and processing costs of commercial permanent magnets and to attempt to fill the empty niche of energy products, 10–20 MGOe, between low-flux (ferrites, alnico) and high-flux (Nd 2Fe 14B- and SmCo 5-type) magnets, we report the synthesis, structure, magnetic properties, and modeling of Ta-, Cu-, and Fe-substituted CeCo 5. Using a self-flux technique, we grow single crystals of Ce 15.1Ta 1.0Co 74.4Cu 9.5, Ce 16.3Ta 0.6Co 68.9Cu 14.2, Ce 15.7Ta 0.6Co 67.8Cu 15.9, Ce 16.3Ta 0.3Co 61.7Cu 21.7, and Ce 14.3Ta 1.0Co 62.0Fe 12.3Cu 10.4. X-ray-diffraction analysis shows that these materials retain a CaCu 5 substructure and incorporate small amounts of Ta in the form of “dumbbells,” filling the 2e crystallographic sites within the one-dimensional hexagonal channel with the 1a Ce site, whereas Co, Cu, and Fe are statistically distributed among the 2c and 3g crystallographic sites. Scanning-electron-microscopy, energy-dispersive-x-ray-spectroscopy, and scanning-transmission-electron-microscopy examinations provide strong evidence of the single-phase nature of the as-grown crystals, even though they readily exhibit significant magnetic coercivities of approximately 1.6 kOe to approximately 1.8 kOe caused by Co-enriched, nanosized structural defects and faults that can serve as pinning sites. Heat treatments at 1040°C for 10 h and hardening at 400°C for 4 hmore » lead to the formation of a so-called composite crystal with a bimodal microstructure that consists of a Ta-poor matrix and Ta-rich laminal precipitates. Formation of the composite crystal during the heat treatment creates a three-dimensional array of extended defects within a primarily single-grain single crystal, which greatly improves its magnetic characteristics. Possible causes for the formation of the composite crystal may be associated with Ta atoms leaving matrix interstices at lower temperatures and/or matrix degradation induced by decreased miscibility at lower temperatures. Furthermore Fe strongly increases both the Curie temperature and magnetization of the system resulting, in ( BH) max ≈ 13 MGOe at room temperature.« less

Authors:
 [1];  [2];  [1];  [2];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [3];  [3];  [1];  [1];  [1]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  2. Iowa State Univ., Ames, IA (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1494934
Alternate Identifier(s):
OSTI ID: 1492120
Report Number(s):
IS-J-9882
Journal ID: ISSN 2331-7019; PRAHB2
Grant/Contract Number:  
AC02-07CH11358
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review Applied
Additional Journal Information:
Journal Volume: 11; Journal Issue: 1; Journal ID: ISSN 2331-7019
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Lamichhane, Tej N., Onyszczak, Michael T., Palasyuk, Olena, Sharikadze, Saba, Kim, Tae -Hoon, Lin, Qisheng, Kramer, Matthew J., McCallum, R. W., Wysocki, Aleksander L., Nguyen, Manh Cuong, Antropov, Vladimir P., Pandey, Tribhuwan, Parker, David, Bud’ko, Sergey L., Canfield, Paul C., and Palasyuk, Andriy. Single-Crystal Permanent Magnets: Extraordinary Magnetic Behavior in the Ta-,Cu-, and Fe-Substituted CeCo5 Systems. United States: N. p., 2019. Web. doi:10.1103/PhysRevApplied.11.014052.
Lamichhane, Tej N., Onyszczak, Michael T., Palasyuk, Olena, Sharikadze, Saba, Kim, Tae -Hoon, Lin, Qisheng, Kramer, Matthew J., McCallum, R. W., Wysocki, Aleksander L., Nguyen, Manh Cuong, Antropov, Vladimir P., Pandey, Tribhuwan, Parker, David, Bud’ko, Sergey L., Canfield, Paul C., & Palasyuk, Andriy. Single-Crystal Permanent Magnets: Extraordinary Magnetic Behavior in the Ta-,Cu-, and Fe-Substituted CeCo5 Systems. United States. doi:10.1103/PhysRevApplied.11.014052.
Lamichhane, Tej N., Onyszczak, Michael T., Palasyuk, Olena, Sharikadze, Saba, Kim, Tae -Hoon, Lin, Qisheng, Kramer, Matthew J., McCallum, R. W., Wysocki, Aleksander L., Nguyen, Manh Cuong, Antropov, Vladimir P., Pandey, Tribhuwan, Parker, David, Bud’ko, Sergey L., Canfield, Paul C., and Palasyuk, Andriy. Fri . "Single-Crystal Permanent Magnets: Extraordinary Magnetic Behavior in the Ta-,Cu-, and Fe-Substituted CeCo5 Systems". United States. doi:10.1103/PhysRevApplied.11.014052.
@article{osti_1494934,
title = {Single-Crystal Permanent Magnets: Extraordinary Magnetic Behavior in the Ta-,Cu-, and Fe-Substituted CeCo5 Systems},
author = {Lamichhane, Tej N. and Onyszczak, Michael T. and Palasyuk, Olena and Sharikadze, Saba and Kim, Tae -Hoon and Lin, Qisheng and Kramer, Matthew J. and McCallum, R. W. and Wysocki, Aleksander L. and Nguyen, Manh Cuong and Antropov, Vladimir P. and Pandey, Tribhuwan and Parker, David and Bud’ko, Sergey L. and Canfield, Paul C. and Palasyuk, Andriy},
abstractNote = {To reduce material and processing costs of commercial permanent magnets and to attempt to fill the empty niche of energy products, 10–20 MGOe, between low-flux (ferrites, alnico) and high-flux (Nd2Fe14B- and SmCo5-type) magnets, we report the synthesis, structure, magnetic properties, and modeling of Ta-, Cu-, and Fe-substituted CeCo5. Using a self-flux technique, we grow single crystals of Ce15.1Ta1.0Co74.4Cu9.5, Ce16.3Ta0.6Co68.9Cu14.2, Ce15.7Ta0.6Co67.8Cu15.9, Ce16.3Ta0.3Co61.7Cu21.7, and Ce14.3Ta1.0Co62.0Fe12.3Cu10.4. X-ray-diffraction analysis shows that these materials retain a CaCu5 substructure and incorporate small amounts of Ta in the form of “dumbbells,” filling the 2e crystallographic sites within the one-dimensional hexagonal channel with the 1a Ce site, whereas Co, Cu, and Fe are statistically distributed among the 2c and 3g crystallographic sites. Scanning-electron-microscopy, energy-dispersive-x-ray-spectroscopy, and scanning-transmission-electron-microscopy examinations provide strong evidence of the single-phase nature of the as-grown crystals, even though they readily exhibit significant magnetic coercivities of approximately 1.6 kOe to approximately 1.8 kOe caused by Co-enriched, nanosized structural defects and faults that can serve as pinning sites. Heat treatments at 1040°C for 10 h and hardening at 400°C for 4 h lead to the formation of a so-called composite crystal with a bimodal microstructure that consists of a Ta-poor matrix and Ta-rich laminal precipitates. Formation of the composite crystal during the heat treatment creates a three-dimensional array of extended defects within a primarily single-grain single crystal, which greatly improves its magnetic characteristics. Possible causes for the formation of the composite crystal may be associated with Ta atoms leaving matrix interstices at lower temperatures and/or matrix degradation induced by decreased miscibility at lower temperatures. Furthermore Fe strongly increases both the Curie temperature and magnetization of the system resulting, in (BH)max ≈ 13 MGOe at room temperature.},
doi = {10.1103/PhysRevApplied.11.014052},
journal = {Physical Review Applied},
number = 1,
volume = 11,
place = {United States},
year = {2019},
month = {1}
}

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