28
This was caused by difficulties with electrochemical systems containing solid, liquid, and gaseous phases to prepare and to maintain clean, well-ordered surfaces for
some time. Surface contamination and surface restructuring that were happening
before the measurements were completed caused irreproducible and unreliable
results.
Most platinum group of metals crystalize in face-centered cubic (fcc) lattice with
the exception of Ru and Os that crystallize in hexagonal close-packed (hcp) lattice.
The two crystal lattices are based upon sheets of spheres arranged at the vertices of
a triangular tiling; they differ in how the sheets are stacked upon one another. They
have the same maximal packing density of atoms and are very close to one another
in energy. In crystallography, most crystal lattices (including fcc) are described with
three basic vectors, the Miller indices as (hkl). Four basic vectors are used in hcp
and rhombohedral surfaces and hence their Miller indices contain four integers,
(h k i l).
Surface structures obtained by cutting metal crystal having face-centered cubic
(fcc) structure at three angles (0, 45, and 54.7°) with respect to the cube sides give
low-index planes, having Miller indices (100), (110), and (111) (Fig. 4.1) [2]. Two
low-index hcp surfaces are depicted in Fig. 4.2. Low-index surfaces reflect the symmetry of the bulk structure; that is, their lateral atomic arrangement should be
Fig. 4.1 Lattice structures of single-crystal surfaces: fcc(111), fcc(100), and fcc(110)
4 Studies of Electrocatalytic Reactions
This was caused by difficulties with electrochemical systems containing solid, liquid, and gaseous phases to prepare and to maintain clean, well-ordered surfaces for
some time. Surface contamination and surface restructuring that were happening
before the measurements were completed caused irreproducible and unreliable
results.
Most platinum group of metals crystalize in face-centered cubic (fcc) lattice with
the exception of Ru and Os that crystallize in hexagonal close-packed (hcp) lattice.
The two crystal lattices are based upon sheets of spheres arranged at the vertices of
a triangular tiling; they differ in how the sheets are stacked upon one another. They
have the same maximal packing density of atoms and are very close to one another
in energy. In crystallography, most crystal lattices (including fcc) are described with
three basic vectors, the Miller indices as (hkl). Four basic vectors are used in hcp
and rhombohedral surfaces and hence their Miller indices contain four integers,
(h k i l).
Surface structures obtained by cutting metal crystal having face-centered cubic
(fcc) structure at three angles (0, 45, and 54.7°) with respect to the cube sides give
low-index planes, having Miller indices (100), (110), and (111) (Fig. 4.1) [2]. Two
low-index hcp surfaces are depicted in Fig. 4.2. Low-index surfaces reflect the symmetry of the bulk structure; that is, their lateral atomic arrangement should be
Fig. 4.1 Lattice structures of single-crystal surfaces: fcc(111), fcc(100), and fcc(110)
4 Studies of Electrocatalytic Reactions