Towards the theory of hardness of materials

@article{Oganov2010TowardsTT,
  title={Towards the theory of hardness of materials},
  author={Artem R. Oganov and Andriy O. Lyakhov},
  journal={Journal of Superhard Materials},
  year={2010},
  volume={32},
  pages={143-147}
}
Recent studies have shown that hardness, a complex property, can be calculated using very simple approaches or even analytical formulae. These form the basis for evaluating controversial experimental results (as we illustrate for TiO2-cotunnite) and enable a systematic search for novel hard materials, for instance, using global optimization algorithms (as we show on the example of SiO2 polymorphs). 

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References

SHOWING 1-10 OF 42 REFERENCES

Intrinsic hardness of crystalline solids

The current status of various theoretical approaches to the “prediction” of material hardness has been reviewed. It is shown that the simple empirical correlation with the shear moduli generally

Microscopic models of hardness

Recent developments in the field of microscopic hardness models have been reviewed. In these models, the theoretical hardness is described as a function of the bond density and bond strength. The

Hardness of covalent crystals.

TLDR
A semiempirical method for the evaluation of hardness of multicomponent crystals is presented and it is found that bond density or electronic density, bond length, and degree of covalent bonding are three determinative factors for the hardness of a polar covalents crystal.

On the hardness of a new boron phase, orthorhombic γ-B28

Measurements of the hardness of a new high-pressure boron phase, orthorhombic γ-B28, are reported. According to the data obtained, γ-B28 has the highest hardness (∼ 50 GPa) of all known crystal-line

Hardness of covalent and ionic crystals: first-principle calculations.

TLDR
It is shown that a lower coordination number of atoms results in higher hardness, contrary to common opinion presented in general literature.

Materials science: The hardest known oxide

TLDR
The discovery of a cotunnite-structured titanium oxide which represents the hardest oxide known is reported, which is one of the least compressible and hardest polycrystalline materials to be described.

Thermodynamic model of hardness: Particular case of boron-rich solids

A number of successful theoretical models of hardness have been developed recently. A thermodynamic model of hardness, which supposes the intrinsic character of correlation between hardness and

Predicting new superhard phases

The search for new superhard materials is of great importance in view of their major roles played for the fundamental science and the industrial applications. Recent experimental synthesis has made

Origin of Superhardness in Icosahedral B12 Materials.

Boron-rich phases with icosahedral symmetry are quite intriguing. It is important to understand the origin of hardness of boron-rich materials. By starting from a chemical bond viewpoint, a simple