Near-Zero Thermal Expansion and High Ultraviolet Transparency in a Borate Crystal of Zn4B6O13

Intrinsic isotropic near-zero thermal expansion is discovered in borate crystal Zn4B6O13 with high transparency in the ultraviolet region. First-principles calculations demonstrate that the very low thermal expansion originates mainly from the invariability of the solid [B24O48] truncated octahedra that are fixed by the [Zn4O13] clusters in the ZBO structure.