## Correction: Young's Modulus and Bulk Modulus Values for Rhodium

**Anonymous**

Posted April 15th, 2008.

It appears there is a mistake in the values of Young's

modulus (E) and bulk modulus (K) for Rhodium.

First, the Poisson's ratio (nu) value of 0.26 matches

that of a standard source, ASM Metals Handbook. The value

for Young's Modulus E, stated in that source is 379 GPa. Any

standard text on mechanics of materials will confirm the

relationship K = E / {3(1-2*nu)} . This relation shows that

for Poisson's ratio less than 1/3, K must be less than E.

If E=379 GPa and nu=0.26, then we should have

K=E/1.44=263.2 GPa.

The webelements page lists nu=0.26, E=275 GPa, and

K=380 GPa. E cannot be less than K, since nu < 1/3.

If the currently stated webelements values for E and K were transposed, they would be closer to the ASM values; please consider doing so as an immediate first step, then check for

the documented sources you trust best. If values of E,nu,K

used for all the other elements are available in spreadsheet

form, it would help to use a spreadsheet and check for consistency with the relation K = E / {3(1-2*nu)}.

There is increasing interest in the mechanical properties

of Rhodium in the community that makes and uses nanowires.

Research papers quoting both values E=379 GPa and E=275 GPa

for Rh in bulk form, have appeared. The second (erroneous)

value may come from the fact that two well-referenced online sources,webelements and the wikipedia entry for Rhodium, both

have the error. It is important to correct it, before the

error is propagated further in papers citing the erroneous

web entry or other papers with the error. I have edited the wikipedia entry as well.