Paul Van Der Sluis

Toward solid-state switchable mirrors using a zirconium oxide proton conductor

The unique optical properties of magnesium rare-earth alloys are interesting for making new types of solid-state electrochromic devices, based on hydrogen transport. These devices can reversibly switch between a transparent and a reflective state, when a potential difference is applied. The all-solid state devices presently studied involve a zirconium oxide proton conductor. This paper discusses the deposition and preliminary characterisation of the solid-state electrolyte. It also gives some information about the performance of a symmetrical GdMg device tested in a hydrogen gas atmosphere. This stack is composed of a GdMgH x /Pd bottom electrode, a ZrO 2 (H 2 O) x [H 2 ] y proton conductor and a Pd/GdMgH y /Pd top-electrode.

Cycling durability of switchable mirrors

Abstract The remarkable optical properties of switchable mirrors, i.e. the ability of lanthanide–magnesium films to switch reversibly between reflecting and transparent states by changing the hydrogen concentration, are interesting for several applications. Since for any application a high cycling durability is necessary, we have studied the durability of various, differently prepared, switchable mirrors. As a model system we have chosen to switch in a 1 M KOH solution. Typical degeneration features that were found included slower kinetics, oxidation and delamination upon cycling of the switchable mirror. Of the various attempts to improve the cycle lifetime, we obtained the best results by using a switchable mirror loaded with hydrogen during deposition.

Lattice relaxation of nanostructured semiconductor pillars observed by high‐resolution x‐ray diffraction

High resolution x‐ray diffraction is used to obtain two‐dimensional reciprocal space maps from two‐dimensional periodic arrays of small (<250 nm) semiconductor pillars. The pillars were made by etching an (001) oriented Si wafer that was epitaxially overgrown with Si1−xGex. The pillars were etched to such a depth that they have a Si bottom and a Si1−xGex top. The shape of the pillars and the lattice parameters in the pillars are determined by comparison of the measured maps with kinematical diffraction model calculations using separate Fourier transformation of the shape of the Si and Si1−xGex parts of the grating. It was found that in the pillars the Si1−xGex lattice was totally relaxed, whereas it was compressively strained prior to etching.