Quick answer: Rare-earth metal sheets and foils are thin, flat or rolled forms used when a project needs a controlled rare-earth composition in a defined geometry. The right specification depends on the element or alloy, purity and impurity limits, length, width, thickness, dimensional tolerance, surface condition, quantity and intended process. For neutron-radiography conversion screens, the sheet must also be evaluated against the radiation source, detector arrangement and handling requirements; the material name alone is not enough.
Heeger Materials' original product table is retained below as the reference list for rare-earth sheet and foil forms. The numbers in that table should be treated as listed reference ranges for the corresponding product entries, not as a universal specification for every grade, batch or application. Confirm the current drawing, analytical basis and inspection method before ordering.
What are rare-earth metal sheets and foils?
Rare-earth sheets and foils are mill products made from selected rare-earth elements or alloys. A sheet is generally specified as a flat product, while a foil is a thinner form that may be supplied flat or in a rolled condition. The boundary between these terms can vary by supplier and specification, so the purchase request should state the required thickness and delivery form directly.
These products are different from rare-earth powders, wires, rods and sputtering targets. Form affects handling, surface area, joining, thermal response, packaging and the way a part is installed. A material that is suitable as a sheet may require different controls when supplied as a foil or fabricated into a disc, shim or custom cut part.
Where can rare-earth sheets and foils be used?
The original article identifies neutron-radiography conversion screens as an important application direction. In that type of system, a material layer interacts with incoming radiation and produces a signal that can expose or activate an imaging medium. The useful design is the complete screen assembly, not an isolated metal coupon, so the source, geometry, detector, shielding, mounting and service environment should be reviewed together.
Rare-earth sheets and foils may also be evaluated for research fixtures, calibration or shielding components, thin shims, custom fabricated parts and other applications where composition and a thin metallic form are needed. These use cases are application-dependent; do not infer a performance result without a defined test method and operating condition.
How should a rare-earth sheet or foil be specified?
A clear inquiry should describe both the material and the finished form. The following points help prevent a nominally correct material from being delivered in an unsuitable geometry or condition.
| Specification item | What to state | Why it matters |
|---|---|---|
| Element or alloy | Element symbol, alloy composition, balance and any controlled additions. | Connects the material to the intended radiation, thermal, electrical or fabrication function. |
| Purity and impurities | Purity basis, critical impurity limits, analytical method and certificate requirement. | Impurities can affect reaction behaviour, radiation response, joining or downstream processing. |
| Form | Flat sheet, foil, coil, disc, shim or another converted shape. | Defines handling, flatness, winding, edge protection and packaging needs. |
| Dimensions | Length, width, thickness, diameter where applicable and drawing revision. | Ensures the material fits the screen, fixture or assembly. |
| Tolerance and surface | Dimensional tolerance, flatness, roughness, edge condition, burr limits and cleaning. | Controls contact, assembly, optical or detector spacing and contamination risk. |
| Environment | Vacuum, inert or reactive atmosphere, temperature range, radiation exposure and storage conditions. | Supports compatibility review and appropriate packaging. |
| Quantity and documentation | Prototype or production quantity, lot traceability, inspection report, material certificate and packaging. | Defines acceptance and repeat-order requirements. |
Rare Earth Metal Sheets Product List
The table below is preserved from the original article. It lists product names, element symbols, reference maximum and minimum dimensions, tolerances and the stated purity note. A dash indicates that the original entry did not provide a numeric value in that cell. Treat those cells as “not listed in the article,” not as proof that the dimension is unavailable.
Product | Materials | Length(mm) | Width(mm) | Thickness(mm) | Purity | |||||||
max | min | Tolerance | max | min | Tolerance | max | min | Tolerance | ||||
Sc | 400 | 10 | 1 | 200 | 10 | 1 | 40 | 0.50 | 0.01 | TREM≥99.95% The purity and impurities can be customized. | ||
Y | 400 | 10 | 1 | 200 | 10 | 1 | 40 | 0.40 | 0.01 | |||
Lanthanum sheets | La | 400 | 10 | 1 | 200 | 10 | 1 | 40 | 0.30 | 0.01 | ||
Cerium sheets | Ce | 300 | 10 | 1 | 150 | 10 | 1 | 40 | 0.40 | 0.01 | ||
Praseodymium sheets | Pr | － | － | 1 | － | － | 1 | － | － | 0.01 | ||
neodymium sheets | Nd | 300 | 10 | 1 | 150 | 10 | 1 | 40 | 0.40 | 0.01 | ||
Promethium sheets | Pm | － | － | 1 | － | － | 1 | 40 | 0.50 | 0.01 | ||
Samarium sheets | Sm | － | － | 1 | － | － | 1 | 40 | 0.50 | 0.01 | ||
Europium sheets | Eu | 200 | 10 | 1 | 150 | 10 | 1 | 40 | 0.50 | 0.01 | ||
Gd | 400 | 10 | 1 | 200 | 10 | 1 | 40 | 0.30 | 0.01 | |||
Terbium sheets | Tb | 300 | 10 | 1 | 150 | 10 | 1 | 40 | 0.30 | 0.01 | ||
Dysprosium sheets | Dy | 400 | 10 | 1 | 200 | 10 | 1 | 40 | 0.30 | 0.01 | ||
Holmium sheets | Ho | 400 | 10 | 1 | 200 | 10 | 1 | 40 | 0.30 | 0.01 | ||
Erbium sheets | Er | 400 | 10 | 1 | 200 | 10 | 1 | 40 | 0.50 | 0.01 | ||
Thulium sheets | Tm | 300 | 10 | 1 | 150 | 10 | 1 | 40 | 0.50 | 0.01 | ||
Yb | 300 | 10 | 1 | 150 | 10 | 1 | 40 | 0.50 | 0.10 | |||
Lutetium sheets | Lu | － | 10 | 1 | － | － | 1 | － | － | 0.01 | ||
What should buyers verify before ordering?
Before releasing a purchase order, ask the supplier to confirm the exact product row, material grade or composition, current dimensions, tolerance basis and analytical documentation. If the sheet will be used in a radiation-conversion assembly, include the source and detector arrangement, active area, mounting method, thermal cycle and any shielding or cleanliness constraints.
- Material identity: Confirm the element or alloy and the basis for reported purity and impurities.
- Geometry: Confirm length, width, thickness, flatness, cut edges and the tolerance on each critical dimension.
- Surface condition: State whether the surface is as-rolled, ground, polished, cleaned or otherwise treated.
- Handling: Define whether the material must be supplied flat, separated with interleaving, wound, sealed or protected from moisture and oxidation.
- Evidence: Request the drawing, inspection report, material certificate and any application-specific test plan that is actually required.
How should rare-earth sheets and foils be inspected?
Inspection should match the function of the part. Dimensional inspection verifies fit, while material and surface checks confirm that the delivered lot matches the purchase specification.
| Inspection area | Possible evidence | Acceptance basis |
|---|---|---|
| Composition and purity | Material certificate, analytical report or agreed composition test. | Purchase specification and impurity limits. |
| Dimensions | Calibrated measurement report for length, width, thickness and critical tolerances. | Approved drawing or order confirmation. |
| Surface and edges | Visual inspection, roughness measurement or edge-condition record where specified. | Defined surface, burr and damage limits. |
| Flatness and handling condition | Flatness check, coil or sheet condition record and packaging inspection. | Assembly fit and transport-protection requirements. |
FAQ
What is the difference between a rare-earth sheet and a foil?
Both are thin metallic forms, but the practical distinction depends on the supplier's product definition and the specified thickness or delivery condition. State the required thickness, flatness and supply form rather than relying on the word “foil” alone.
Can the dimensions in the product table be treated as guaranteed for every order?
No. The table is a reference list from the original article. Confirm the current grade, drawing, tolerance basis, purity documentation and inspection method for the specific order.
Why is gadolinium mentioned in connection with neutron radiography?
Gadolinium can interact strongly with thermal neutrons and is therefore considered in some conversion-screen designs. The actual screen response depends on material condition, thickness, geometry, source spectrum, detector arrangement and measurement method.
What information should be sent for a custom rare-earth sheet inquiry?
Send the element or alloy, purity and impurity limits, shape, length, width, thickness, tolerances, surface condition, quantity, intended application, operating environment and documentation requirements.
Conclusion
Rare-earth metal sheets and foils should be selected as engineered material forms, not only by element name. Start with the application, then define chemistry, purity, dimensions, tolerance, surface condition, handling and evidence requirements. The retained product table provides a useful starting reference, while a current drawing and application-specific review are needed for a reliable order.
For a custom rare-earth sheet or foil requirement, provide the target composition, drawing and operating conditions through the Heeger Materials contact page.