| Pentagonal Bifrustum | |
| Type: | Bifrustum |
| Faces: | 10 trapezoids 2 pentagons |
| Edges: | 25 |
| Vertices: | 15 |
| Dual: | Elongated pentagonal dipyramid |
| Properties: | Convex |
| Net: | Dual elongated pentagonal dipyramid net.png |
In geometry, the pentagonal bifrustum or truncated pentagonal bipyramid is the third in an infinite series of bifrustum polyhedra. It has 10 trapezoidal and 2 pentagonal faces.
The pentagonal bifrustum is the dual polyhedron of a Johnson solid, the elongated pentagonal bipyramid.
This polyhedron can be constructed by taking a pentagonal bipyramid and truncating the polar axis vertices. In Conway polyhedron notation, it can be represented as the polyhedron "", meaning the truncation of the degree-five vertices of the dual of a pentagonal prism.[1]
Alternatively, it can be constructed by gluing together two end-to-end pentagonal frustums, or (if coplanar faces are allowed) by gluing together two pentagonal prisms on their pentagonal faces.
In nanoparticles, a 15-site truncated pentagonal bipyramid structure may form the nucleus of larger twinned structures with five-fold or icosahedral symmetry.[2]