Enhanced Adhesion Energy at Oxide/Ag Interfaces for Low-Emissivity Glasses: Theoretical Insight into Doping and Vacancy Effects.

Low-emissivity glasses rely on multistacked architectures with a thin silver layer sandwiched between oxide layers. The mechanical stability of the silver/oxide interfaces is a critical parameter that must be maximized. Here, we demonstrate by means of quantum-chemical calculations that a low work of adhesion at interfaces can be significantly increased via doping and by introducing vacancies in the oxide layer. For the sake of illustration, we focus on the ZrO2(111)/Ag(111) interface exhibiting a poor adhesion in the pristine state and quantify the impact of introducing n-type dopants or p-type dopants in ZrO2 and vacancies in oxygen atoms (nVO; with n = 1, 2, 4, 8, 10, 16), zirconium atoms (mVZr; with m = 1, 2, 4, 8), or both (nVO + mVZr; with m/n = 1:2, 1:4, 2:2, 2:4). In the case of doping, interfacial electron transfer promotes an increase in the work of adhesion, from initially 0.16 to ∼0.8 J m-2 (n-type) and ∼2.0 J m-2 (p-type) at 10% doping. A similar increase in the work of adhesion is obtained by introducing vacancies, e.g., VO [VZr] in the oxide layer yields a work of adhesion of ∼1.5-2.0 J m-2 at 10% vacancies. An increase is also observed when mixing VO and VZr vacancies in a nonstoichiometric ratio (nVO + mVZr; with 2n ≠ m), while a stoichiometric ratio of VO and VZr has no impact on the interfacial properties.

Symmetry recovery for coupled photonic modes with transversal PT symmetry.

Typical parity-time (PT) symmetric structures switch from the unbroken to the broken phase when gain increases through an exceptional point. In contrast, we report on systems with the unusual, reverse behavior, where the symmetric phase is recovered after a broken phase. We study this phenomenon analytically and numerically in the simplest possible system, consisting of four coupled modes, and we present potential dielectric and plasmonic implementations. The complex mode merging scheme, with two distinct unbroken PT phases encompassing a broken one, appears for a specific proportion range of the coupling constants. This regime with "inverse" exceptional points is interesting for the design of novel PT devices.