Revisiting the Cocktail Effect in High-Entropy Layered Double Hydroxides: Linear Additivity Rather than Emergent Behavior.

High-entropy layered double hydroxides (HE-LDHs) have attracted interest because compositional complexity is often assumed to generate emergent properties. Here, we examine whether this concept extends to dielectric relaxation and charge transport. Eight binary, medium-entropy, and high-entropy LDHs with configurational entropies (Sconf) of 0.53R-1.66R (R = gas constant) and an overall MII/MIII ≈ 3 were synthesized by mechanochemical activation followed by hydrothermal treatment. The in-plane lattice parameter correlated linearly with the average cation radius, supporting homogeneous cation incorporation. All compositions exhibited conductivity-assisted dielectric relaxation with a single relaxation process consistently observed in tan δ, ε″, and M″. Relaxation times were proportional to conductivity and were accurately predicted by composition-weighted linear additivity, with HE-LDHs showing intermediate behavior between binary end members. Comparison of small- and large-pellet geometries separated grain and grain-boundary responses, revealing higher through-plane conductivity in grain interiors. Spin-polarized density functional theory calculations using a realistic 5 × 5 special quasi-random structure supercell showed that the band gap of the [Mg0.329Ni0.209Co0.198Al0.161Fe0.103](OH)2 monolayer is intermediate between those of binary LDHs. Together, these results show that compositional complexity alone does not produce emergent electrical properties. The dielectric and electronic responses remain predictable from composition-weighted linear additivity.