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Single-Crystal Silicon Sphere - 25 to 100 mm Diameter

  • The "New Kilogram" silicon sphere.
2.00 LBS
8 weeks from receipt of payment
Free Shipping

Product Description

These are single-crystal silicon spheres machined from optical-grade silicon boules.  The CNC machining technique used assures that the polish is uniform around the sphere, not subject to the effects of the crystal orientation that may appear during surface polishing. 

We offer silicon spheres in these sizes;

Diameter (mm)   Mass (gm) 
25 6.87
37.5 23.2
50 27.5
75 46.4
100 110


As with all silicon exposed to air, the surface of the sphere is actually silicon dioxide a few atoms thick.

Technical Specifications

  • Atomic Number: 14
  • Atomic Weight: 28 (nominal, some 29 and some 30 may be present)
  • Resistivity: Greater than 10 ohm-cm (high infrared transmission but not AR coated)
  • Scratch and pit: 60/40 (not normally visible to the naked eye)
  • Surface roughness: 2.5 nm RMS (as if the tallest mountain on earth was 4 feet high)

The picture shows one of the silicon spheres made in Australia as part of the Avogadro project, a precursor to redefining the kilogram using an object with a known number of atoms.  This sphere is about 93 mm in diameter.

The Rules (No Exceptions)

All silicon sphere orders must be fully prepaid by bank wire.  We will provide the bank details at purchase.

Orders are non-cancellable for any reason; prepayments are non-refundable, silicon spheres are non-returnable.

Spheres are fabricated to order.  This takes about 8 weeks.  The clock starts when payment is received.

Purchasers may select a fired ceramic stand similar to that shown in the picture at no cost.

These spheres are sold without warranty.  They are single crystals, not metal balls.  If you drop them, they will shatter.

Custom Items

We can supply spheres of other diameters and physical characteristics on special order.  Please inquire if you are interested.



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