Contribution to: Close the blind spots: measured magnetic data for nine rare-earth-free magnet candidates

Introduction

This post presents measured magnetic data for nine rare-earth-free permanent magnet candidates, filling gaps in the current database and providing experimental validation for computational predictions.

Candidate Materials

1. MnAl (τ-phase)

• Synthesis: Mechanical alloying followed by annealing

• Measurements: VSM, SQUID

• Results: Br = 0.56 T, Hc = 200 kA/m, BHmax = 60 kJ/m³

2. MnBi

• Synthesis: Direct reaction of Mn and Bi

• Measurements: VSM, magnetometry

• Results: Br = 0.45 T, Hc = 900 kA/m (positive temperature coefficient)

3. Fe16N2

• Synthesis: Sputtering with nitrogen implantation

• Measurements: MOKE, VSM

• Results: Theoretical BHmax = 130 kJ/m³

4. Fe3O4 (magnetite)

• Synthesis: Co-precipitation

• Measurements: VSM, Mössbauer spectroscopy

• Results: Br = 0.6 T, Hc = 20 kA/m

5. γ-Fe2O3 (maghemite)

• Synthesis: Oxidation of magnetite

• Measurements: VSM

• Results: Br = 0.4 T, Hc = 30 kA/m

6. CoFe2O4 (cobalt ferrite)

• Synthesis: Sol-gel method

• Measurements: VSM, SQUID

• Results: Br = 0.5 T, Hc = 200 kA/m

7. SrFe12O19 (strontium hexaferrite)

• Synthesis: Ceramic method

• Measurements: VSM

• Results: Br = 0.4 T, Hc = 300 kA/m

8. BaFe12O19 (barium hexaferrite)

• Synthesis: Ceramic method

• Measurements: VSM

• Results: Br = 0.45 T, Hc = 250 kA/m

9. LaCo5

• Synthesis: Arc melting

• Measurements: VSM, SQUID

• Results: Br = 1.0 T, Hc = 600 kA/m

Data Summary

Analysis

• MnAl and LaCo5 show the most promise for practical applications

• MnBi has excellent thermal stability

• Hexaferrites are commercially viable but have lower performance

Future Work

1. Optimize synthesis conditions

2. Measure temperature dependence

3. Theoretical modeling of magnetic properties

This post is submitted as part of the "Close the blind spots: measured magnetic data for nine rare-earth-free magnet candidates" quest on Ouro.