Zirconium is a chemical element with the atomic number 40 in the periodic table. With 65 parts per million by weight, it’s a relatively abundant metal found in Earth’s crust. Being a member of the transition metals family of periodic table elements, this strong transition metal has four valence electrons in its outer shell.
Known since antiquity, zirconium nowadays has a wide everyday application, ranging from the manufacturing of artificial gems with brilliance greater than the one of diamonds to its use in nuclear reactors.
Chemical and Physical Properties of Zirconium
The symbol in the periodic table of elements: Zr
Atomic number: 40
Atomic weight (mass): 91.22 g.mol-1
Group number: 4 (Transition metals)
Period: 5 (d-block)
Color: A gray-white, lustrous substance with a golden hue
Physical state: Solid at 20°C
Half-life: From 50# ms [>170 nanoseconds] to 20(4)×1018 y
Electronegativity according to Pauling: 1.2
Density: 6.52 g.cm−3
Melting point: 1854°C, 3369°F, 2127 K
Boiling point: 4406°C, 7963°F, 4679 K
Van der Waals radius: 0.160 nm
Ionic radius: 0.08 nm (+4)
Most characteristic isotope: 90Zr, 92Zr, 94Zr
Electronic shell: [Kr]4d25s2
The energy of the first ionization: 669 kJ.mol-1
The energy of the second ionization: 1346 kJ.mol-1
The energy of the third ionization: 2312 kJ.mol-1
The energy of the fourth ionization: 3256 kJ.mol-1
Discovery date: In 1789 by Martin Heinrich Klaproth
With the periodic table symbol Zr, atomic number 40, atomic mass of 91.22 g.mol-1, and electron configuration [Kr]4d25s2, zirconium is strong, ductile, and malleable gray-white metal with a silvery luster. It reaches its boiling point at 4406°C, 7963°F, 4679 K, while the melting point is achieved at 1854°C, 3369°F, 2127 K. This member of the transition metals family of the periodic table has an electronegativity of 1.2 according to Pauling, whereas the atomic radius according to van der Waals is 0.160 nm.
Zirconium has a simple hexagonal crystal structure and has two phases: an alpha phase and a beta phase. The atoms of this chemical element form close-packed hexagonal α-Zr at room temperature, while at a temperature of 863 °C the structure shifts to body-centered β-Zr.
Furthermore, this transition metal has strong anticorrosive properties and is resistant to extremely high temperatures. It shares the chemical properties with the chemical element classified under Zr in the periodic table – titanium.
Element 40 forms a protective film when exposed to air at room temperature. The flimsy protection made by the oxides or nitrides passivate zirconium and lead to ‘zirconium weakness’ which makes this metal even more resistant to weak acids, acidic salts, and seawater.
How Was Zirconium Discovered?
Hyacinth and zircon are gemstones containing the pure, elemental form of the chemical element zirconium. Due to their attractive appearance, they have been used by the ancient civilizations for decoration. These aesthetically pleasing gems were labeled as ‘zircon’ since ancient times.
The Discovery of Martin Heinrich Klaproth
In 1789, this zirconium was observed as a new chemical element found in the oxides of zircon (ZrSiO4, zirconium orthosilicate), by the German chemist and apothecary Martin Heinrich Klaproth (1743-1817).
Klaproth analyzed a zircon (zirconium silicate) sample labeled as ‘jargon’ that had been obtained from Ceylon, Sri Lanka in an effort to determine the chemical composition of the mineral. The results from his chemical trial uncovered that the mineral sample was composed of 25% of silica, 0.5% of iron oxide, and 70% of a new oxide. The German scientists named the new oxide ‘zirconerde’.
It was clear to Klaproth that he has a new chemical element in front of him, only he wasn’t able to isolate it in the pure, elemental form.
The Contribution of Jöns Jacob Berzelius
After the failed attempt of Sir Humphry Davy to obtain pure zirconium metal by conducting electrolysis, the Swedish chemist Jöns Jacob Berzelius joined the effort of his fellow scientists. In 1824, Berzelius heated an iron tube containing a mixture of potassium and potassium zirconium fluoride (K2ZrF6) to a high temperature, which yielded an amorphous black powder with poor thermal-conductive properties and could spontaneously ignite when exposed to air. It was the pure metal form of the new element – zirconium (Zr).
How Did Zirconium Get Its Name?
The name of this chemical element originates from the Arabic (or Persian) word ‘zargun‘, meaning ‘gold colored’.
Where Can You Find Zirconium?
Zirconium found in the Earth’s crust originates from S-type stars. Namely, the spectrum of this late-type giant star displays bands of zirconium oxide, also including yttrium oxide, technetium, cyanogen, titanium oxides, vanadium oxides, and lithium as s-process elements. The heavier elements are formed exactly in the S-type stars by neutron capture.
According to Los Alamos National Laboratory, this chemical element is also identified in the Sun, the meteorites, and in lunar rocks. In comparison with the terrestrial rocks, Apollo missions to the moon have delivered evidence of a surprisingly high zirconium oxide content in the lunar rock samples.
Naturally occurring zirconium can be mostly found in the minerals zircon, ziekelite, baddeleyite, and eudialyte. Traces of zirconium are also uncovered from some rare earth minerals, obtained from monazite sand. The aforementioned zirconium minerals zirconium contain from a few tenths of 1 percent to several percent hafnium contents.
Mineral zircon is the only source for commercial exploitation of this chemical element. It typically occurs in alluvial deposits in stream beds, old lake beds, or ocean beaches and seawater. The second most important zirconium mineral is baddeleyite, only the extraction of the zirconium metal from this type of mineral is more expensive.
The Crystal Bar Process (or the Iodide Process) refers to the first industrial process for the commercial production of metallic zirconium, which was discovered by Anton Eduard van Arkel and Jan Hendrik de Boer in 1925. The purest, elemental form of this transition metal can be derived by thermal decomposition of zirconium tetraiodide (ZrI4), or with the Kroll process, i.e. by magnesium reduction of zirconium tetrachloride (ZrCl4).
Zirconium’s largest deposits in the world are located in Australia, South Africa, Indonesia, Mozambique, China, Sri Lanka, and India.
List of Zirconium Minerals
Naturally, zirconium can be found in the following mineral compounds:
- Eudialyte group
Zirconium in Everyday Life
From imitating diamonds in jewelry to the production of nuclear energy, zirconium is a crucial material in many industrial branches.
- This metal is used in nuclear reactors as engineering material due to its high transparency to neutrons. The small quantity of hafnium that is present in all zirconium ores must be thoroughly removed by a liquid-liquid countercurrent-extraction procedure before the element 40 is used in the nuclear reactors because Hf possesses strong neutron absorption power;
- One of zirconium’s most important applications is in nuclear submarines and nuclear reactors for cladding fuel rods;
- Zirconium is often used as an alloying agent in uranium and magnesium alloys; the strong anti-corrosive property of this element makes it also suitable for making pumps, valves, and heat exchangers;
- The element 40 is also used as a getter for removing residual gases in electron tubes, due to its strong affinity for gases, especially the oxygen gas;
- Element 40 is often an additive of choice for many steel manufacturers. Furthermore, it’s used in the manufacturing of furnace bricks, surgical instruments, television glass, removing residual gases from vacuum tubes, photoflash bulbs, explosive primers, rayon spinnerets, lamp filaments, etc.
- The impure oxide (zirconia) is used for making laboratory crucibles that will be able to withstand extremely high-temperature shocks;
- Zirconium dioxide is often used as a gem-diamond simulant for making less expensive crystals that resemble diamonds in jewelry. This zirconium compound is also used in laboratory crucibles, as a refractory material, and in the metallurgical furnaces;
- ZrO2 is frequently used by the chemical industry as a component of acid- and alkali-resistant glasses, as well as of ceramics employed in fuel cells;
- Some antiperspirants and water purification systems also contain zirconium in their composition;
- The main industrial role of zirconium tetrachloride is the one of a catalyst in the chemical reactions such as cracking of petroleum and polymerization of ethylene;
- Superconductive magnets often contain zirconium as one of the main components. Namely, when alloyed with zinc, zirconium adopts magnetic property at temperatures below 35°K (-238.15°C);
- Zirconium oxide is found in ultra-strong ceramics which are later used as ceramic knife-blades, scissors, and golf irons;
- Titanium, niobium, zirconium, and tantalum alloys have wide medical and surgical applications;
- In dentistry, zirconium veneers are some of the strongest and most stain-resistant tooth-replicating materials;
- Bicycle frames that have zirconium in their structure are both strong and lightweight;
- Obtained as a result of the attack of sulfuric acid on zirconium hydroxide, Zr(OH), zirconium sulfate has wide industrial use as a lubricant, a chemical reagent, as well as in the tanning process of white leather.
Zirconium and Health
Zirconium is found in the human body as a trace element in minuscule amounts. It’s estimated that there are about 10 parts per billion of zirconium in our body. The extremely low concentration of this trace mineral in the body’s tissue makes zirconium’s function still undetermined. Basically, it has no biological role.
By binding to serum proteins, this chemical element passes through the blood-brain barrier and absorbs into the brain.. It also can enter the placental barrier and milk of lactating women.
Which Foods Contain Zirconium?
Zirconium is not a trace mineral that we readily expect to intake via our daily nutrition. However, it does occur in some foods, such as:
- European plum;
- Brown rice;
- Cereal grains;
How Dangerous Is Zirconium?
According to NIOSH, zirconium is considered to be a substance with no toxic properties. The pure, elemental form of element 40 is not classified either as genotoxic or carcinogenic. However, zirconium dust can enter the lungs if inhaled, and the foreign particles may trigger severe bouts of coughing and irritate the eyes or the mucous membranes of the body. Zirconium metal and zirconium compounds may also irritate the skin.
Zirconium-95 is the form of element 40 that is a component of the atmospheric testing of nuclear weapons. Since it’s one of the longest living isotopes of zirconium, the prolonged exposure to this particular radioisotope may lead to the occurrence of tumorous growth and cancer.
It should be noted that zirconium compounds can be highly toxic due to the inclusion of more toxic and radioactive chemical elements than zirconium. Exposure to the zirconium compounds may result in mild bronchial asthma, gastrointestinal problems, or granulomatous and fibrotic changes in the lungs.
The miners employed in the zirconium extracting sites or in the nuclear technology industry are at the greatest risk of developing zirconium toxicity as an occupational disease.
Despite the popular use of zirconium as a jewelry decoration, allergic contact dermatitis after prolonged exposure to zirconium does not seem to have been reported.
Environmental Effects of Zirconium
Despite the fact that the pure, elemental form of zirconium does not present any danger to the environment, its radioactive forms may spread and contaminate it as a result of the nuclear testing, as aforementioned. Otherwise, this chemical element has no known biological role, even though it’s widespread in nature.
Isotopes of Zirconium
There are 40 observed isotopes of zirconium, of which five comprise the naturally occurring form of this chemical element: zirconium-90 (51.46 % of abundance), zirconium-91 (11.23 % of abundance), zirconium-92 (17.11 % of abundance), zirconium-94 (17.40 % of abundance), zirconium-96 (2.80% of abundance).
While 90Zr is the most abundant form of element 40, zirconium-96 is the longest living form of this transition metal with a half-life of 20(4)×1018 years.
Zirconium forms radioisotopes that emit moderate radiation and that can be damaged by neutron bombardment.
|Z||N||Isotopic mass (Da)
[n 2][n 3]
[n 4][n 5]
[n 7][n 5]
|Natural abundance (mole fraction)|
|Excitation energy||Normal proportion||Range of variation|
|79Zr||40||39||78.94916(43)#||56(30) ms||β+, p||78Sr||5/2+#|
|81Zr||40||41||80.93721(18)||5.5(4) s||β+ (>99.9%)||81Y||(3/2−)#|
|β+, p (<.1%)||80Sr|
|83Zr||40||43||82.92865(10)||41.6(24) s||β+ (>99.9%)||83Y||(1/2−)#|
|β+, p (<.1%)||82Sr|
|88Zr[n 8]||40||48||87.910227(11)||83.4(3) d||EC||88Y||0+|
|93Zr[n 10]||40||53||92.9064760(25)||1.53(10)×106 y||β− (73%)||93mNb||5/2+|
|94Zr[n 9]||40||54||93.9063152(26)||Observationally stable[n 11]||0+||0.1738(28)|
|95Zr[n 9]||40||55||94.9080426(26)||64.032(6) d||β−||95Nb||5/2+|
|96Zr[n 12][n 9]||40||56||95.9082734(30)||20(4)×1018 y||β−β−[n 13]||96Mo||0+||0.0280(9)|
|105Zr||40||65||104.93305(43)#||0.6(1) s||β− (>99.9%)||105Nb|
|β−, n (<.1%)||104Nb|
List of Zirconium Compounds
When zirconium participates in a chemical compound, it typically adopts an oxidation state of +4. Element 40 is able to absorb oxygen, nitrogen, and hydrogen in extremely large quantities. When exposed to a temperature of over 800 °C (1,500 °F), zirconium forms a strong chemical reaction with oxygen which results in the ZrO2 oxide. Most zirconium compounds are white in color. Its oxide (ZrO2) is white, as well.
The following is a list of the most common zirconium compounds:
- Cubic Zirconia
- Hadean zircon
- Lead zirconate titanate
- Sodium Zirconium Cyclosilicate
- Tetragonal Polycrystalline Zirconia
- Yttria-stabilized Zirconia
- Zirconium Acetylacetonate
- Zirconium Boride
- Zirconium Bromide
- Zirconium Carbide
- Zirconium Diboride
- Zirconium Dioxide
- Zirconium Disilicide
- Zirconium Disulfide
- Zirconium Fluoride
- Zirconium Hydrogen Carbonate
- Zirconium Hydroxide
- Zirconium Hypochlorite
- Zirconium Iodide
- Zirconium Lactate
- Zirconium Nitrate
- Zirconium Nitride
- Zirconium Nitride
- Zirconium Orthosilicate
- Zirconium Perchlorate
- Zirconium Phosphate
- Zirconium Phosphide
- Zirconium Propanoate
- Zirconium Selenide
- Zirconium Silicide
- Zirconium Sulfate
- Zirconium Sulfide
- Zirconium Telluride
- Zirconium Tetrafluoride
- Zirconium Tetrahydroxide
- Zirconium Tungstate
- Zirconium Tungstate
- Zirconium Uranate
- Zirconium(Iii) Chloride
- Zirconium(Ii) Hydride
- Zirconium(Iv) Bromide
- Zirconium(IV) Chloride
- Zirconium(Iv) Chloride
- Zirconium(IV) Cyanide
- Zirconium(IV) Dichromate
- Zirconium(IV) Dihydrogen Phosphate
- Zirconium(IV) Ferrocyanide
- Zirconium(IV) Hydride
- Zirconium(Iv) Hydroxide
- Zirconium(Iv) Iodide
- Zirconium(IV) Metasilicate
- Zirconium(IV) Nitrite
- Zirconium(IV) Oxide
- Zirconium(IV) Perchlorate
- Zirconium(IV) Permanganate
- Zirconium(IV) silicate
- Zirconium(IV) sulfate
- Zirconyl chloride
- (Cyclopentadienyl)Zirconium Trichloride
5 Interesting Facts and Explanations
- While the term cubic zirconium refers to the chemical element with an atomic number 40 and element symbol Zr, cubic zirconia is the synthetically produced form of crystalline zirconium dioxide (ZnO2) that resembles diamonds in physical appearance, but has more brilliant shine than them.
- Zircon (zirconium silicate, ZrSiO4) is a natural gemstone more brilliant than diamonds. This primary gemstone of zirconium is also known under the following names: jargon, hyacinth, jacinth, or ligure. The synthetic cubic zirconia (zirconium dioxide, ZrO2) is manufactured as a highly popular and low-cost substitute for diamonds.
- Zirconolite (CaZrTi2O7) is a titanate that is used for dating old rocks by using specialized electron microscopy techniques. The data derived by zirconolite are known to be more precise than the data obtained by zircon.
- Martin Heinrich Klaproth’s apothecary was the second largest of the type in Berlin. It was also considered to be the most productive artisanal chemical research center in Europe.
- Zircaloy is a term used for zirconium alloys whose main characteristics include high resistance to corrosion, high hardness; as well as very low absorption cross-section of thermal neutrons.