Office of the Secretary of Defense: 13_Supplement_to_Metallic_Specimen

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According to Podolskiy et al., Bi can theoretically function as a waveguide when it exists as a
single crystalline layer between surfaces with sufficient dielectric () constants.1 As a single
crystalline layer, Bi displays anisotropic  properties.2 Anisotropic  properties cause
electromagnetic waves to propagate non-uniformly across different axes. Podolskiy et al. assert
that a monocrystalline layer of Bi has sufficient  anisotropy to guide THz frequency waves.
This specimen’s intermixed composition of Pb indicates that Bi never existed as a pure layer,
regardless of any processing effects that may have altered the crystalline structure. Therefore,
this specimen’s elemental and structural characteristics do not meet the conditions to
theoretically function as a waveguide.
ORNL and AARO could not determine whether this specimen was a fragment of a larger object.
However, this specimen’s delamination, oxidation, and structural characteristics are consistent
with exposure to environmental and mechanical stresses over time.3 In its current form, the
specimen probably does not represent its original configuration, condition, or
application. Despite these complicating factors, AARO draws two distinct conclusions from
ORNL’s findings:
First, the specimen’s physical properties are consistent with a material of terrestrial origin.
Materials exhibit a predictable isotopic signature when formed in and exposed to terrestrial
conditions. This specimen’s isotopic signature is consistent with terrestrial signatures and does
not exhibit expected interstellar signatures.4 5 6 7 8
Second, the specimen’s structural and elemental properties are inconsistent with the anisotropic 
properties required to theoretically function as a waveguide.2
Historical Context and Likely Origin
Starting in 1915 and peaking during World War II, there was widespread domestic research on
Mg alloys for airframes, engines, weapons, and delivery systems. At the time, researchers did
not fully understand Mg corrosion and other failure mechanisms. 9 10 11 Many projects studied
magnesium-zinc (Mg-Zn) alloys with 1-4 wt.% Zn in Mg.12 13 14 Other projects studied the
impact of Pb and Bi additives on Mg alloys for corrosion resistance. This research found that Pb
and Bi would concentrate at the surface due to lower surface tension, consistent with the banding
seen in this specimen.15 The specimen’s grain structure, Zn concentration, and banding of Bi/Pb
are also consistent with out-of-equilibrium processes, such as vapor deposition in a vacuum
chamber that may have contained impurities. Before 1970, vapor deposition manufacturing
techniques were not fully mature, and achieving pristine thin films remained challenging.16 17
Research, development, testing, and evaluation is an iterative process of trial and error. This
process subjects test objects to conditions designed to evaluate material limits and identify
modes of failure. Historically, the scientific community has not extensively documented failed
experiments. Many experimental Mg alloys failed for reasons not well understood at the time of
testing, e.g., stress corrosion cracking. 18 19 20 21 Unsurprisingly, records of failed Mg alloy
designs are scant. Neither AARO nor ORNL could verify the specimen’s historical
origin. Unverifiable, conflicting personal accounts complicate its undocumented chain of013Page determined to be Unclassified
Reviewed by Chief of Staff, AARO
IAW FY24 NDAA, Section 1841 (a)(1)(C)
Date: 02/06/2025