Introduction to Zirconium
Zirconium finds many applications as a heat- and corrosion-resistant element. Zirconium is derived from zircon (ZrSiO4) and baddeleyite (ZrO2), which are its most common minerals. The name zirconcium is derived from the Persian word zargun, meaning gold-like. It is quite common in the earth’s crust, but can be difficult to refine. Over time, numerous chemists have worked to isolate and make the metal by decomposing and reducing compounds like zirconium tetraiodide, ZrI4, and zirconium tetrachloride, ZrCl4.
Ten Interesting and Fun Facts About Zirconium
- Zircon is mainly found in Australia, South Africa, India, and the USA, and hundreds of thousands of tons are mined every year.
- An average human body contains about 250 milligrams of zirconium, which can come from beef, eggs, and whole wheat.
- Scientists have identified zirconium in the sun, meteorites, and a certain star.
- Researchers have dated a zircon mineral of 4.4 billion years as the oldest material on earth.
- Zirconium is an ideal material for jewelry, notably for people with skin allergies, since it is pure and excludes other irritants.
- Zircaloy (zirconium alloys) can be used for nuclear applications since zirconium does not readily absorb neutrons. Industries use zirconium for cladding fuel rods in nuclear reactors.
- The correct atomic mass of zirconium could not be determined until 1924 because, before then, it was unknown that zirconium always contains small amounts of hafnium, which skewed the atomic mass experiment results.
- Approximately 0.016% of the earth’s crust is zirconium.
- Zirconium is generally soft and pliable.
- In solid form, zirconium is less prone to ignition, but in fine powder form, zirconium is highly flammable and can spontaneously ignite.
Zirconium in the Periodic Table
Zirconium’s symbol is Zr, with atomic number 40 and an atomic mass of 91.224 amu. This means that there are 40 protons within the nucleus of a zirconium atom, and 40 electrons around its nucleus in its neutral state. It is located on the d-block of the periodic table, with Yttrium on its left and Niobium on its right. It is a transitional metal in group 4 and period 5. Zirconium has an electron configuration of [Kr] 4d25s2 and four valence electrons. On the Pauling scale, Zirconium has a medium-low electronegativity value of approximately 1.33.
Zirconium in Today’s World
Applications of Zirconium
Since zirconium is highly heat- and corrosion-resistant, it is a useful and versatile component in many materials. Zirconium may be used in catalytic converters, furnace bricks, and nuclear applications. In nuclear reactors, industrialists use zirconium for coating fuel rods, stopping leakage of radioactive materials, reactor-core structures, and uranium alloys. However, scientists must remove hafnium, which is present in all zirconium ores, before reactor use as hafnium absorbs thermal neutrons, unlike zirconium. Baddeleyite, a zirconium mineral, is useful for lab crucibles, which are heated to high temperatures to melt other substances. Zircon is valuable for refractories, ceramic opacification, and jewelry. Zirconium is also a component of surgical instruments, television glass, and photographic bulbs, and is a hardening agent in alloys like steel. In jewelry, zirconium dioxide (ZrO2) is useful as an artificial gemstone as it can resemble diamonds.
Current Research with Zirconium
Revolutionary uses of zirconium have been discovered over the past few decades. For example, zirconia, a crystalline oxide of zirconium, has become increasingly popular in restorative and prosthetic dentistry choices. Getting a zirconia crown can prevent further decay in your teeth, cause less damage on opposing teeth, and act as a generally stronger choice for tooth restorations. In 3D printing, zirconium oxide suspensions are suitable for 3D printing technology enabling the printing of zirconia-based dental materials, allowing dental prostheses to exactly match the desired shapes.
When and How was the Element Zirconium Discovered?
In 1789, Martin Heinrich Klaproth discovered zirconium in a sample of zircon from Sri Lanka. Jöns Jakob Berzelius first isolated and presented the metal in 1824 in an impure form. In 1925, the metal was first produced in quantity by thermal decomposition of zirconium tetraiodide, ZrI4 by Anton E. van Arkel and J.H. de Boer. William Justin Kroll developed a cheaper process of making zirconium by reducing zirconium tetrachloride, ZrCl4, by magnesium.
Zirconium Compounds
Oxides, nitrides, and carbides
Zirconium dioxide, ZrO2 (also known as zirconia) is clear and white-colored and is useful for thermal barrier coating and diamond substitutes as its melting point is around 2,700°C.
Zirconium tungstate (ZrWO4) is unusual because it shrinks when heated, whereas most other substances expand when heated.
Zirconyl carbide (ZrC) and zirconium nitride (ZrN) are refractory solids.
Halides
ZrF4, ZrI4, ZrCl4, and ZrBr4 all tend to hydrolyze and many are used to isolate zirconium.
Additionally, zirconium sulfate (Zr(SO4)2) is useful as a lubricant, as a chemical reagent, and in white leather tanning.
Physical Properties of the Element Zirconium
- Symbol: Zr
- Melting point: 1854°C
- Boiling point: 4406°C
- Density (g cm-3): 6.52
- Atomic mass: 91.224 amu
- Atomic number: 40
- Electronegativity: 1.33
- Classification: Transition metal
- Natural abundance of Zirconium in the earth’s crust: 0.016%
- Electron shell configuration: [Kr] 4d25s2
- Isotopes: The isotopes of zirconium are 90Zr, 91Zr, 92Zr, 94Zr, and 96Zr.
- Minerals: Zirconium can be naturally found in the minerals zircon (ZrSiO4) and baddeleyite (ZrO2).
- Toxicity: Zirconium is generally non-toxic.
Zirconium Oxidation States
Zirconium is mainly in the +4 oxidation state in its compounds, but some less stable compounds can contain zirconium in the +3 or +2 oxidation states.
Isolation of Zirconium
One must convert zirconium into zirconium dioxide by boiling zircon, reacting it with coke to form zirconium carbonitride, and reacting the new result with chlorine to form zirconium tetrachloride. Zirconium tetrachloride is then reduced to zirconium metal in the Kroll process with magnesium in a helium atmosphere. There are other methods of isolating zirconium, however, that are being researched, since zirconium is abundant on earth but difficult to separate.
Where Can I Buy Zirconium?
You can order pure zirconium from online sites, as well as zirconia, other zirconium compounds, and less pure forms of zirconium.