Zirconium
transition metal · period 5 · group 4 · d-block
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name zirconium is taken from the name of the mineral zircon (the word is related to Persian zargun (zircon; zar-gun, "gold-like" or "as gold")), the most important source of zirconium.
What the numbers say
At standard temperature and pressure Zirconium is a solid, sitting in period 5, group 4 of the d-block.
Its melting point of 2128 K (1855 °C) is the 17th highest of the 110 elements with a measured value — mid-range among the elements.
At 6.511 g/cm³ it is the 55th densest of 96 elements with a quoted density.
Pauling electronegativity is 1.33. Paired with oxygen (3.44) that is a difference of 2.11, which puts the bond predominantly ionic — expect a stable oxide ceramic.
In the solid state it takes a simple hexagonal structure — hexagonal packing offers few easy slip systems, so properties are anisotropic and formability is limited.
It is reported in 4 oxidation states (1, 2, 3, 4), which sets how many distinct compounds and phases it can form.
First identified in 1789.
Crystal structure
Solid Zirconium adopts a Simple Hexagonal arrangement, in the Hexagonal system — axes a = b ≠ c, angles α = β = 90°, γ = 120°. Symmetry controls the anisotropy of stiffness and thermal expansion, and the available slip systems set how far the metal deforms before it fractures.
Crystallographic examples
Zirconium or one of its compounds is a textbook example for this crystal system:
- Monoclinic — β-S, gypsum, monoclinic ZrO₂, augite
Check it against computed structures
The structure search queries the Materials Project, OQMD and the Open Materials Database for computed crystal structures containing Zr — with DFT formation energy, hull stability and band gap where the provider publishes them.
K 2 · L 8 · M 18 · N 10 · O 2
Properties
| Atomic number | 40 |
|---|---|
| Atomic mass | 91.2242 u |
| Series | transition metal |
| Group | 4 |
| Period | 5 |
| Block | d-block |
| Phase at STP | Solid |
| Density | 6.511 g/cm³ |
| Melting point | 2128 K (1855 °C) |
| Boiling point | 4650 K (4377 °C) |
| Electronegativity (Pauling) | 1.33 |
| Electron configuration | [Kr] 4d² 5s² |
| Crystal structure | Simple Hexagonal |
| Oxidation states | 1,2,3,4 |
| Discovered | 1789 |
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See Zr in context with all 118 elements.
Working with zirconium in a real design?
Ask the materials chat how Zr behaves in your alloy system, what it does to weldability, and which grades to look at — with the source of every number named.