Promethium (Pm) is the odd one out in the rare earth series: it has no stable isotopes and is virtually absent in nature. That single fact explains almost everything about its uses and market structure.
Promethium is used because specific promethium isotopes (especially Pm-147) are useful, not because promethium is mined and traded like other rare earths. Most promethium supply is tied to reactor/fission production and isotope separation, so its "uses" behave more like radioisotope applications than commodity applications.
When industry says "promethium," it usually means Pm-147, a beta-emitting radioisotope that can be manufactured in reactors and chemically separated for use in devices.
One of the most consistent, practical uses of Pm-147 is as a beta source for non-contact thickness or basis-weight measurement in manufacturing.
The U.S. DOE isotope marketplace page explicitly calls out beta thickness gauging for thin films as a key industrial use. This sits inside the broader category of nucleonic measurement systems used across industry (thickness, coating weight, etc.).
Promethium-147 has a long history in betavoltaic and direct-charge radioisotope battery research because it emits beta particles that can be converted into electricity in specialized devices.
DOE's isotope program material lists power source in nuclear batteries as a recognized application. A peer-reviewed reactor production paper also frames Pm-147 demand around beta batteries and other low-power, long-lived sources.
This is not a "mass market" like lithium batteries. It's specialized, heavily regulated, and typically constrained by:
Promethium has been used in self-luminous materials where beta radiation excites a phosphor to emit light. This is more "legacy industrial and instrument" than mainstream consumer.
A U.S. NRC document explicitly references regulatory treatment for promethium-147 contained in luminous products (timepieces, hands, dials), which is a direct signal that this use exists as a recognized category.
Practical takeaway: when you see promethium mentioned in luminous applications, think "regulated sealed source / controlled products," not a modern consumer growth engine.
Promethium isotopes are also used in:
This bucket tends to be smaller, procurement-driven, and dependent on institutional or industrial demand rather than broad economic cycles.
Promethium is not a normal magnet rare earth. It is not driving EV motors, turbines, or consumer electronics magnets. If you're looking for that kind of demand profile, you're in NdPr/Dy/Tb territory, not Pm.
Promethium's "market" is better understood as:
When industrial sectors expand capacity and upgrade process control, demand for gauging sources and systems can rise.
Promethium supply is fundamentally tied to planned production runs, irradiation capacity, and chemical separation throughput. The U.S. isotope program material is a good example of how supply is organized and marketed.
Many promethium uses are source-based and regulated. That makes adoption slow and stable, not viral.
Industrial beta thickness gauging is one of the most consistently cited uses for Pm-147.
Yes, especially Pm-147 in betavoltaic/direct-charge battery concepts, but it's niche and regulation-heavy.
Because it's virtually absent in nature due to radioactivity and lack of stable isotopes, so practical supply is produced via nuclear pathways, not mining.