icryst

Single crystal electrodes for electrochemistry (Clavilier-type bead crystals)

Metal single crystals
Small diameter: 2-3 mm
Oriented (111), (001), (110), or vicinals orientations
Orientation accuracy: < 0.5°
Surface polished
Materials: Cu, Mo, Rh, Pd, Ag, Ta, W, Re, Ir, Pt, Au, PtPd, PtRh, AuAg, and PtIr
Easy cleaning by flame annealing

Applications:

Electrochemistry
Molecular layers
UHV surface studies

Gold bead single crystal

Copper bead single crystal

Platinum bead single crystal

For the fabrication of small metal bead crystals (Clavilier type electrodes) a gas flame is used normally. Due to oxidation occurring under ambient conditions bead crystals could be manufactured only from noble metals. Now icryst uses electron beam heating under vacuum conditions in order to prevent oxidation. Therefore it is now possible to manufacture bead crystals from a wide variety of metals and metal alloys. Due to the use of clean starting materials and clean manufacturing processes in vacuum the incorporation of contaminations which can be introduced by the usual spark erosion (EDM) is prevented. Narrow x-ray diffraction peaks confirm a high crystal quality of the bead crystals. Such small metal single crystals can be used for a wide variety of applications in electrochemistry, surface science, thin film growth, and related fields.

Typical dimensions

Cyclic voltammograms of low index surfaces of Pt, Au, Cu, and Rh bead crystals prepared by icryst

Au(100): The voltammogram in NaOH 0.1M was was published by by Rodriguez, Kwon and Koper in Nature Chemistry, 4 (2012) 177

Pt(111): The sharp peak indicates the high degree of ordering of the surface. The voltammogram was provided by the Surface Chemistry and Catalysis group (Leiden Institute of Chemistry) in The Netherlands.

Au(100): The sharp peak indicates the high degree of ordering of the surface. The voltammogram was provided by G. Beltramo (Research Center Juelich).

Cu(111) in 5 mM H2SO4. The anodic peak in the positive voltage sweep is associated with the adsorption of sulfate. The voltammogram was provided by Klaas Jan Schouten at the Surface Chemistry and Catalysis group Leiden Institute of Chemistry, The Netherlands.

Rh(111): The voltammogram was is published: Qinqin Xu, Udo Linke, Renata Bujak and Thomas Wandlowski, Electrochimica Acta, 54 (2009) 5509

STM image of the surface structure of a Pt(111) bead crystal after cleaning by heating 1000C°. The surface shows atomic steps and is free of contaminations. Image size 500nm.

STM image of the surface structure of a Pt(100) bead crystal under ambient conditions after cleaning by heating to 1000C°. The surface reconstruction can be seen as parallel lines with 1.4 nm periodicity. Image size 120 nm x 120 nm.

Optical microscope image of a Au bead crystal heated by an electron beam during solidification (The diameter of the crystal is 2 mm). The solidified upper part of the bead is darker than the hot liquid part in the lower part of the image. The phase boundary between solid and liquid part is seen clearly. The contaminations accumulated after zone refining are indicated by an arrow in the top. The (111) facets formed on the solidified part of the bead are indicated by arrow heads.

Also spherical bead crystals are available. Left: SEM image of a platinum bead crystal (diameter ~2.5 mm). Low index (111) facets on the bead crystal are indicated by arrows. Right: Zoom to one of the (111) facets. The flat (111) facet is surrounded by an alternating array of step bunches and facets.

Now also larger bead crystals can be prepared. The photo shows a platinum bead crystal with a diameter of 4 mm.

We offer bead crystals according to your specific demands. Please do not hesitate to discuss your requests with us. Further offers: info@icryst.com