pub const SIC_4H_DENSITY_G_CM3: f64 = 3.211;Expand description
4H-SiC density, “3.211 g cm-3, 300 K”, credited to Gomes de Mesquita (1967) by the Ioffe NSM archive SiC basic-parameters page (read 2026-10-08; primary not opened). Provisional: that Acta Cryst. 23, 610 (1967) is titled “Refinement of the crystal structure of SiC type 6H” (Crossref), so the attribution to 4H is doubtful. Used in the number-density test, which records the 4H disagreement as a gap.
No measured 4H bulk density could be opened (checked 2026-10-10). The
one open primary found, N. W. Thibault, Am. Mineral. 29, 327 (1944),
pp. 327-328 and Table 25 on p. 342, gives for α-SiC type III (4H)
only a cell (a = 3.073 Å, c = 10.053 Å) and a calculated density
of 3.217; its one measured (pycnometric) density, d at 30°/4° C =
3.218 (p. 341), is of type II (6H).
Two open measured 4H densities were found on 2026-10-11, and neither
replaces this value: D. Lundqvist, Acta Chem. Scand. 2, 177 (1948), p. 182,
σ_obs. = 3.201 + 0.005 on impure type III with a little type I (Al
0.30 %), which the Lattice::silicon_carbide_4h cell exceeds by 3.88e-3,
2.5 times the stated 0.005; and ORNL/TM-2023/3059 (2023), Table 4, p. 7,
3.17 and 3.21 g/cm³ by dimensions and mass for two 4H wafers, a 1.3e-2
spread with no temperature or uncertainty stated. Both are pinned in
tests/crystal_hex.rs; the 4H density criterion of #179 stays unmet. See
docs/data-provenance.md.