Author(s)

Hans Hermann Otto

Materialwissenschaftliche Kristallographie, Clausthal University of Technology, Clausthal-Zellerfeld, Germany.

Recently, many seminal papers deal with the syntheses, stability and superconducting properties of super-hydrides like LaH₁₀ or YH₁₀ under high pressure, reporting critical temperatures near room temperature. In the first run one will assume that the involved metal atoms contribute a number of 3 electrons to the pairing pool corresponding to their valence. However, another possibility may be that the cationic valence is somewhat smaller, for instance only 2.29, resulting in a nominal electron number per cation of σ₀ = 0.229 ≈ 3/13 instead of 0.3. Then, we will have a numerical equality to the optimum hole number in the cuprate high-T_c superconductors, a number that reflects the fractal nature of electronic response in superconductors. However, if one still keeps up the oxidation state of +3 of lanthanum, one will need 13 hydrogen atoms to match the optimum σ₀. Such composition may be found at the phase boundary between the observed LaH₁₀ and LaH₁₆ phases. Partial ionic replacement is suggested to shift the super-hydride composition into the σ₀ optimum. Micro-structural phenomena such as multiple twinning and ferroelastic behavior as observed with cuprates may also influence the superconductivity of super-hydrides. Finally, epitaxial growth of super-hydrides onto a specially cut diamond substrate is proposed.

Superconductivity, Super-Hydride, Clathrate, LaH₁₀, YH₁₀, Faujasite, High Pressure, Optimum of Pairing Charge Carriers, Slab Width, Ionic Substitution, Epitaxial Growth, Diamond Substrate, Fractality

Otto, H. (2019) Super-Hydrides of Lanthanum and Yttrium: On Optimal Conditions for Achieving near Room Temperature Superconductivity. World Journal of Condensed Matter Physics, 9, 22-36. doi: 10.4236/wjcmp.2019.91002.