The cluster formula [Ti-Cu6Ti8]Cu3, with e/u ≈ 23.6, was taken as the basic composition formula.
The relatively pure product is subject to further characterization for cluster formula determination.
This cluster, after being glued with one Fe atom, produces a cluster formula [B B2Fe8]FeB3Fe9Fe75B25 that presents nearly 24 valence electrons.
According to this model, any structure can be expressed by cluster formula [cluster](glue atom)x, x denoting the number of glue atoms matching one cluster.
A type of cluster formula [B–(B6 − x/2Cx/2)](B1 − x/2Mgx/2)(x ≤ 2), that contains 24 valence electrons per unit cluster formula, was derived from relevant crystalline borides B12C2Mg and B7Mg.
We have previously proposed the "cluster-plus-glue-atom" model for metallic glasses and the relevant cluster formula [cluster](glue atom)x, x ∼ 1 or 3.
This multi-principal-element alloy is developed out of a cluster formula [Al M14]Al1 issued from the cluster-plus-glue-atom model of a BCC structure.
A cluster formula [NiFe12](Cr2Ni) with surplus Ni was then determined to ensure the second phase (Ni3M) precipitation, based on which new multi-component alloys [(Ni,Cu 16Fe192](Cr32(Ni,Mo,Ti,Nb,Al,V)16) were designed.
Finally, using general cluster formula [cluster](glue atoms)x(x = 1, 3), Mg-based Mg67Zn28Ca5 bulk metallic glass may be deciphered via the most close-packed eutectic cluster Zn2Mg11 as: [Zn2Mg11] + (Zn2Ca1).
The key step of deriving the right cluster that enters into the cluster formula, termed the principal cluster, is emphasized, including defining the nearest-neighbor cluster and determining the principal cluster that is most representative for the phase structure.
