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YOU CAN MAKE A PERMANENT MAGNET OUT OF IRON AND NITROGEN

Make permanent magnets from iron and nitrogen instead of rare earths, then build the instrument that proves whether they actually work.

by Ben Krasnow

FULL CAD BOM FIRMWARE DOCS

ScienceWorkshop

difficulty
●●●●●
time
several weekends
license
license not specified
repo
repo 0 stars

WHAT YOU’LL NEED

Videos
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COMPAREE VERDICT

This is Ben Krasnow showing how to make iron nitride magnet material and — just as importantly — how to measure whether you succeeded. The process follows a published paper: iron powder and ammonium nitrate are ground so hard in a planetary ball mill that the nitrate decomposes and nitrogen diffuses into the iron. The powder is then annealed for about a day at around 200 °C, sealed in an argon-filled glass ampoule, because going hotter loses the wanted crystal phase. Instead of the paper's explosive shock compaction, he casts the powder in epoxy. The measurement half is a home-built vibrating sample magnetometer that plots the magnetisation curve, showing remanence and coercivity rather than whether something sticks to a fridge. The ball mill plans and materials list are published on GitHub; the magnetometer you reverse-engineer from the video. The result is honest: it is a real but weak magnet, not competitive with ceramic or neodymium magnets. The thing most likely to go wrong is oxidation: the nanoscale powder can ignite when the mill is opened in air, and Ben suspects oxidation hurt his result.

GOOD TO KNOW

  • —This is a filmed demonstration; the ball mill plans and materials list are on GitHub, the rest you take from the video and the linked paper.
  • —The YouTube video shows the full process and measurement on camera.
  • —Ball mill CAD and materials list are published; there are no circuit diagrams or parts list for the vibrating sample magnetometer.
  • —You will be reverse-engineering the magnetometer and the process details from the footage and the paper.
  • —The ball mill plans are MIT licensed; the video itself has no licence for the process or the magnetometer.
  • —The video is freely available but this is a watch-and-replicate build, not a packaged project.

Parts to buy

6 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • Iron powderFind
  • Ammonium nitrateFind
  • Milling balls and the parts for the planetary ball millFind
  • Argon and glass ampoulesFind
  • Epoxy for castingFind
  • Parts for a vibrating sample magnetometerfrom the repo files

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Can I build this?

Printnothing required
Buyiron powder, ammonium nitrate, milling balls and the parts for the planetary ball mill (materials list on GitHub), argon and glass ampoules, epoxy for casting, and the parts for a vibrating sample magnetometer
Toolsthe planetary ball mill (build from the published plans), a kiln or oven that holds about 200 °C, a way to seal glass ampoules under argon, and an electronics and machining bench for the magnetometer
Skillsmaterials science background helpful, machining if you build the mill, electronics for the tracer, patience with heat treatment and phase control
Timeseveral weekends: building the ball mill, a few days of milling, a day-long anneal, epoxy casting, and the magnetometer build
CostMid-range budget, dominated by building the planetary ball mill and the magnetometer; the chemicals are cheap
SafetyMilled nanoscale iron powder can ignite on contact with air — in the video particles caught fire when the chamber was opened. Ammonium nitrate is a strong oxidiser; keep quantities small and away from fuels and heat. Sealing glass ampoules and the kiln anneal involve hot glass and high temperatures.

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

Videos

Iron nitride permanent magnets made with DIY ball mill and tested with DIY magnetometer

Full process and measurement on camera. The ball mill plans and materials list are linked from the description; the magnetometer has no published plans.

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Gallery

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Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Watch the full Applied Science video (The video is the main reference for the process and the magnetometer; the description also links the paper and the ball mill plans on GitHub. Take notes on the heat treatment setup and the magnetometer.)
  2. 2.Decide whether to buy or build the ball mill(The process needs a high-energy planetary ball mill; Ben's plans, CAD and materials list are on GitHub.)
  3. 3.Source iron powder and ammonium nitrate, read the linked paper, and plan an oxygen-free anneal at about 200 °C(Ben sealed the milled powder in an argon-filled glass ampoule and annealed it in a kiln for about a day at around 200 °C. Ammonium nitrate is a strong oxidiser — store and handle it accordingly.)
  4. 4.Build the vibrating sample magnetometer(Reverse-engineer it from the footage. The magnetometer is what tells you whether you made a magnet or just magnetic dust.)

KNOWN ISSUES

  • Only the ball mill has published plans; the process comes from a paper and the magnetometer from the video.
  • The anneal is the delicate step: too hot (above about 200 °C) and you lose the wanted iron nitride phase, and any oxygen degrades the nanoscale powder.
  • The anneal is gentle (about a day at around 200 °C) but must be oxygen-free: Ben sealed the powder in an argon-filled glass ampoule, and above about 200 °C the wanted phase is lost.
  • The vibrating sample magnetometer is custom electronics and mechanics with no published plans. If you have never built precision measurement gear, that is a learning curve on top of the magnet.
  • Expect a weak magnet. The theory says iron nitride could rival neodymium, but Ben's DIY sample was weaker than even ceramic magnets.
  • Multiple heat treatment runs are likely. The first batch will teach you what went wrong.

Are there project files I can download?

Partly. The planetary ball mill has published plans and a materials list on GitHub (MIT licence, with CAD files). The process follows a paper linked in the description, and the vibrating sample magnetometer you reverse-engineer from the video.

Can I skip the hysteresis tracer and just test if it sticks to something?

That tells you almost nothing. The magnetometer gives you the magnetisation curve, with remanence and coercivity — the numbers that define a permanent magnet. Without it you do not know if you succeeded.

How strong are these compared to neodymium magnets?

Much weaker, at least in this build. Ben's sample showed real retentivity and coercivity but was worse than ceramic, alnico or samarium cobalt magnets. The interest in iron nitride is that some researchers think its theoretical limit is above neodymium, from cheap iron and nitrogen, but nobody has demonstrated that yet.

What is the single most expensive part?

Probably the planetary ball mill, which has to grind hard enough for days to drive nitrogen into the iron (plans are on GitHub), followed by the home-built vibrating sample magnetometer. The anneal itself only needs a kiln or oven that holds about 200 °C for a day and an argon-filled sealed ampoule.

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Discussion1

FROM THE COMPAREE TEAM

The vibrating sample magnetometer is the more reusable half: it proves whether you made a magnet or just rust. What material would you characterise first if you built one?

CompareeTEAM1mo agoedited

Practical notes from our verification: there is no project repository for this build, but the video description links the main paper and the plans and materials list for the planetary ball mill (benkrasnow/Planetary_Ball_Mill on GitHub). The process is ball milling iron powder with ammonium nitrate so hard that nitrogen diffuses into the iron, then annealing at about 200°C for around a day; going hotter can ruin the phase. Oxidation is the real enemy: Ben sealed the powder in an argon-filled glass ampoule before the kiln, still had to open the mill in air, and says his result may have been hurt by oxidation. The test rig is a home-built vibrating sample magnetometer with a lock-in amplifier, and it is the more reusable half. Expect a weak magnet: the measured curve shows real retentivity and coercivity, but it is not competitive with ceramic or neodymium magnets. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.

Ben Krasnow

Ben Krasnow runs Applied Science, a YouTube channel where he builds scientific instruments and investigates materials and processes that are usually locked behind expensive labs. The channel is known for showing the entire process on camera, not just the results.

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