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About Strontium

Strontium Bohr

In 1790 a Scottish physician named Adair Crawford was the first to distinguish strontium-containing minerals from barium minerals. He had examined a supposed barium carbonate sample from the mine at Strontian, Argyleshire and upon finding that the sample lacked the expected chemical properties, proposed that he had found a new “earth”--a novel natural compound that likely contained a previously unknown element. Many of his contemporaries confirmed the results of his experiments and supported his assessment, and the name “strontium” was given to the new element based upon the origins of the source mineral. It was not until 1808 that Sir Humphry Davy succeeded in isolating the pure metal, a difficult task due to strontium’s high reactivity with water and air. He ultimately succeeded using electrolysis of a mixture of mercury and strontium oxides, a method that also allowed him to produce barium and calcium metals for the first time.

Strontium’s earliest industrial use was in the extraction of sugar from sugar beet molasses through a chemical procedure known as the Strontian process. This method is now obsolete, but strontium remains in use primarily due to the unique chemistry of its compounds. Strontium salts typically burn a bright red, and for this strontium compounds, especially strontium nitrate, are included in fireworks, flares, and tracer ammunition. Strontium oxide is used in pottery glazes to replace alternative compounds which contain toxic lead or barium. When added to glass, the same compound increases hardness, strength, and the index of refraction. This produces a higher-quality glass suitable for optical applications. Additionally, strontium glass blocks UV and X-ray radiation, and for this reason is included in cathode ray tube (CRT) display faceplates. This was once one of the largest uses of strontium, before the use of CRT displays began to decline. Strontium ferrite is a ceramic compound used to produce high strength magnets. These magnets are useful for their resistance to corrosion, low density, effectiveness at high-temperatures, and and their ability to be very permanently magnetized. They are generally found in small motors, speakers, decorative magnets, and toys.

Strontium additionally has important medical uses resulting from its chemical similarities to calcium. Though not needed in the body, strontium is taken up by the bones just like calcium, and is known to promote calcium uptake, increasing bone density. Strontium ranelate is used as a drug treatment for patients with osteoporosis, and succeeds in strengthening bones and preventing breaks. Additionally, the radioisotope strontium-89 is used to treat pain from metastatic bone cancer, as it will localize to the bones naturally and kill the cancer cells there, stopping the extreme pain caused by tumors growing within the bones. Strontium gels have even been investigated as promoters of bone growth in bone tissue engineering. Strontium chloride also serves a medical function, as it treats tooth sensitivity when included in toothpaste.

Strontium metal is used fairly rarely, but it is added to some aluminum alloys to improve their ability to be cast into detailed structures, and it also finds occasional use as a chemical reagent.

Strontium, like its fellow alkali earths, is highly reactive, and therefore is never found naturally in the form of the pure metal. Its primary mineral deposits are celestite, a strontium sulfate mineral, and strontiantite, a carbonate mineral. Though the vast majority of strontium compounds used are derived from the carbonate, celestite is more commonly mined, as it tends to occur more frequently in deposits large enough to exploit economically. Almost all of the strontium extracted is therefore converted from the sulfate to the carbonate. For the rare cases where strontium metal is needed, it is produced by reducing strontium oxide with aluminum.

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High Purity (99.999%) Strontium (Sr) Sputtering Target Strontium has low tech applications as an additive to flares and pyrotechnics because of the bright crimson flame produced by its salts. It alsoHigh Purity (99.999%) Strontium Oxide (SrO) Powder has many high technology applications because of its high refractive index as a titanate in glass, as a "getter" in electron tubes and as a dopant for numerous perovskite formulations to produce cathodes for oxygen generation or solid oxide fuel cells. Historically the primary use of strontium has been to produce CRT glass for color televisions and computer monitors. Strontium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Elemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Strontium oxide is available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Strontium fluorides is an insoluble strontium source for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Strontium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Strontium Properties

Strontium (Sr) atomic and molecular weight, atomic number and elemental symbolStrontium is a Block S, Group 2, Period 5 element. The number of electrons in each of Strontium's shells is 2, 8, 18, 8, 2 and its electron configuration is [Kr] 5s2. Strontium Bohr ModelThe strontium atom has a radius of 215.pm and its Van der Waals radius is 249.pm. In its elemental form, CAS 7440-24-6, strontium has a silvery white metallic appearance. Strontium is found in celestite and strontianite ores. Elemental StrontiumStrontium was discovered by William Cruickshank in 1787 and first isolated by Humphry Davy in 1808. Strontium was named after the Scottish town it was discovered in.

Symbol: Sr
Atomic Number: 38
Atomic Weight: 87.62
Element Category: alkaline earth metal
Group, Period, Block: 2, 5, s
Color: silvery white
Other Names: Stronzio, Estrôncio
Melting Point: 777 °C, 1430.6 °F, 1050.15 K
Boiling Point: 1377 °C, 2510.6 °F, 1650.15 K
Density: 2.54 g/cm3
Liquid Density @ Melting Point: 2.375 g/cm3
Density @ 20°C: 2.6 g/cm3
Density of Solid: 2630 kg/m3
Specific Heat: 0.0719 Cal/g/K @ 25°C
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 9.16
Heat of Vaporization (kJ·mol-1): 154.4
Heat of Atomization (kJ·mol-1): 164.4
Thermal Conductivity: 0.354 W/cm/K @ 298.2 K
Thermal Expansion: 22.5 µm·m-1·K-1 (25 °C)
Electrical Resistivity: 23.0 nΩ·cm @ 20 °C
Tensile Strength: N/A
Molar Heat Capacity: 26.4 J·mol-1·K-1
Young's Modulus: 15.7 GPa
Shear Modulus: 6.03 GPa
Bulk Modulus: N/A
Poisson Ratio: 0.28
Mohs Hardness: 1.5
Vickers Hardness: N/A
Brinell Hardness: N/A
Speed of Sound: N/A
Pauling Electronegativity: 0.95
Sanderson Electronegativity: 0.72
Allred Rochow Electronegativity: 0.99
Mulliken-Jaffe Electronegativity: 1.00 (sp orbital)
Allen Electronegativity: 0.963
Pauling Electropositivity: 3.05
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 38
Protons: 38
Neutrons: 50
Electron Configuration: [Kr] 5s2
Atomic Radius: 215 pm
Atomic Radius, non-bonded (Å): 2.49
Covalent Radius: 195±10 pm
Covalent Radius (Å): 0.9
Van der Waals Radius: 249 pm
Oxidation States: 2, 1 (strongly basic oxide)
Phase: Solid
Crystal Structure: face-centered cubic
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) 4.63
1st Ionization Energy: 549.48 kJ·mol-1
2nd Ionization Energy: 1064.25 kJ·mol-1
3rd Ionization Energy: 4138.29 kJ·mol-1
CAS Number: 7440-24-6
EC Number: 231-133-4
MDL Number: MFCD00134060
Beilstein Number: N/A
SMILES Identifier: [SrH2]
InChI Identifier: InChI=1S/Sr
InChI Key: CIOAGBVUUVVLOB-UHFFFAOYSA-N
PubChem CID: 5359327
ChemSpider ID: 4514263
Earth - Total: 14.5 ppm
Mercury - Total: 1.11 ppm
Venus - Total: 15.2 ppm
Earth - Seawater (Oceans), ppb by weight: 8100
Earth - Seawater (Oceans), ppb by atoms: 570
Earth -  Crust (Crustal Rocks), ppb by weight: 360000
Earth -  Crust (Crustal Rocks), ppb by atoms: 85000
Sun - Total, ppb by weight: 50
Sun - Total, ppb by atoms: 0.7
Stream, ppb by weight: 60
Stream, ppb by atoms: 0.7
Meterorite (Carbonaceous), ppb by weight: 8900
Meterorite (Carbonaceous), ppb by atoms: 2000
Typical Human Body, ppb by weight: 4600
Typical Human Body, ppb by atom: 330
Universe, ppb by weight: 40
Universe, ppb by atom: 0.06
Discovered By: William Cruickshank
Discovery Date: 1787
First Isolation: Humphry Davy (1808)

Health, Safety & Transportation Information for Strontium

The non-radioactive isotopes of Strontium are not toxic. Safety data for Strontium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental (metallic) Strontium.

Safety Data
Material Safety Data Sheet MSDS
Signal Word Danger
Hazard Statements H260-H315
Hazard Codes F,Xi
Risk Codes 11-14-36
Safety Precautions 26
RTECS Number UN 3208 4.3/PG 1
Transport Information N/A
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Exclamation Mark-Acute Toxicity Flame-Flammables

Strontium Isotopes

Strontium has four stable isotopes: 84Sr (0.56%), 86Sr (9.86%), 87Sr (7.0%) and 88Sr (82.58%).

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
73Sr 72.96597(64)# >25 ms β+ to 73Rb; β+ + p to 72kr 1/2-# N/A 579.71 -
74Sr 73.95631(54)# 50# ms [>1.5 µs] β+ to 74Rb 0+ N/A 596.18 -
75Sr 74.94995(24) 88(3) ms β+ to 75Rb; β+ + p to 74kr (3/2-) N/A 610.78 -
76Sr 75.94177(4) 7.89(7) s β+ to 76Rb 0+ N/A 626.31 -
77Sr 76.937945(10) 9.0(2) s β+ to 77Rb; β+ + p to 76kr 5/2+ N/A 638.11 -
78Sr 77.932180(8) 159(8) s β+ to 78Rb 0+ N/A 650.85 -
79Sr 78.929708(9) 2.25(10) min β+ to 79Rb 3/2(-) N/A 661.73 -
80Sr 79.924521(7) 106.3(15) min EC to 80Rb 0+ N/A 674.46 -
81Sr 80.923212(7) 22.3(4) min EC to 81Rb 1/2- 0.544 683.47 -
82Sr 81.918402(6) 25.36(3) d EC to 82Rb 0+ N/A 696.21 -
83Sr 82.917557(11) 32.41(3) h EC to 83Rb 7/2+ -0.898 705.22 -
84Sr 83.913425(3) Observationally Stable - 0+ N/A 717.02 0.56
85Sr 84.912933(3) 64.853(8) d EC to 85Rb 9/2+ -1.001 726.04 -
86Sr 85.9092602(12) STABLE - 0+ N/A 736.91 9.86
87Sr 86.9088771(12) STABLE - 9/2+ -1.09283 745.92 7
88Sr 87.9056121(12) STABLE - 0+ N/A 756.79 82.58
89Sr 88.9074507(12) 50.57(3) d β- to 89Y 5/2+ -1.149 763.01 -
90Sr 89.907738(3) 28.90(3) y β- to 90Y 0+ N/A 771.09 -
91Sr 90.910203(5) 9.63(5) h β- to 91Y 5/2+ -0.887 776.37 -
92Sr 91.911038(4) 2.66(4) h β- to 92Y 0+ N/A 783.52 -
93Sr 92.914026(8) 7.423(24) min β- to 93Y 5/2+ N/A 788.8 -
94Sr 93.915361(8) 75.3(2) s β- to 94Y 0+ N/A 795.95 -
95Sr 94.919359(8) 23.90(14) s β- to 95Y 1/2+ N/A 800.3 -
96Sr 95.921697(29) 1.07(1) s β- to 96Y 0+ N/A 806.52 -
97Sr 96.926153(21) 429(5) ms β- to 97Y; β- + n  to 96Y 1/2+ N/A 809.94 -
98Sr 97.928453(28) 0.653(2) s β- to 98Y; β- + n  to 97Y 0+ N/A 816.15 -
99Sr 98.93324(9) 0.269(1) s β- to 99Y; β- + n  to 98Y 3/2+ N/A 819.57 -
100Sr 99.93535(14) 202(3) ms β- to 100Y; β- + n  to 99Y 0+ N/A 825.79 -
101Sr 100.94052(13) 118(3) ms β- to 101Y; β- + n  to 100Y (5/2-) N/A 829.21 -
102Sr 101.94302(12) 69(6) ms β- to 102Y; β- + n  to 101Y 0+ N/A 837.29 -
103Sr 102.94895(54)# 50# ms [>300 ns] β- to 103Y N/A N/A 845.37 -
104Sr 103.95233(75)# 30# ms [>300 ns] β- to 104Y 0+ N/A 844.13 -
105Sr 104.95858(75)# 20# ms [>300 ns] Unknown N/A N/A 852.21 -
Strontium Elemental Symbol

Recent Research & Development for Strontium

  • Strontium and zoledronate hydroxyapatites graded composite coatings for bone prostheses. Boanini E, Torricelli P, Sima F, Axente E, Fini M, Mihailescu IN, Bigi A. J Colloid Interface Sci. 2015 Feb 9
  • Strontium still authorised despite an unfavourable opinion of the European Pharmacovigilance committee. [No authors listed] Prescrire Int. 2015 Jan
  • Middle Holocene daily light cycle reconstructed from the strontium/calcium ratios of a fossil giant clam shell. Hori M, Sano Y, Ishida A, Takahata N, Shirai K, Watanabe T. Sci Rep. 2015 Mar 4
  • Tracking mobility using human hair: What can we learn from lead and strontium isotopes? Vautour G, Poirier A, Widory D. Sci Justice. 2015 Jan
  • Optimizing strontium ruthenate thin films for near-infrared plasmonic applications. Braic L, Vasilantonakis N, Zou B, Maier SA, Alford NM, Zayats AV, Petrov PK. Sci Rep. 2015 Mar 13
  • Supplementation of strontium to a chondrogenic medium promotes chondrogenic differentiation of human dedifferentiated fat cells. Okita N, Honda Y, Kishimoto N, Liao W, Azumi E, Hashimoto Y, Matsumoto N. Tissue Eng Part A. 2015 Feb 11.
  • The osteogenic response of mesenchymal stromal cells to strontium-substituted bioactive glasses. Santocildes-Romero ME, Crawford A, Hatton PV, Goodchild RL, Reaney IM, Miller CA. J Tissue Eng Regen Med. 2015 Mar 11.
  • Fabrication of gelatin-strontium substituted calcium phosphate scaffolds with unidirectional pores for bone tissue engineering. Wu YC, Lin WY, Yang CY, Lee TM. J Mater Sci Mater Med. 2015 Mar
  • Provenancing of unidentified World War II casualties: Application of strontium and oxygen isotope analysis in tooth enamel. Font L, Jonker G, van Aalderen PA, Schiltmans EF, Davies GR. Sci Justice. 2015 Jan
  • Effects on growth and osteogenic differentiation of mesenchymal stem cells by the strontium-added sol-gel hydroxyapatite gel materials. Raucci MG, Giugliano D, Alvarez-Perez MA, Ambrosio L. J Mater Sci Mater Med. 2015 Feb
  • Age and gender specific biokinetic model for strontium in humans. Shagina NB, Tolstykh EI, Degteva MO, Anspaugh LR, Napier BA. J Radiol Prot. 2015 Mar
  • In vitro and in vivo evaluation of strontium-containing nanostructured carbonated hydroxyapatite/sodium alginate for sinus lift in rabbits. Valiense H, Barreto M, Resende RF, Alves AT, Rossi AM, Mavropoulos E, Granjeiro JM, Calasans-Maia MD. J Biomed Mater Res B Appl Biomater. 2015 Feb 26.
  • Repairing defect and preventing collapse of femoral head in a steroid-induced osteonecrotic of femoral head animal model using strontium-doped calcium polyphosphate combined BM-MNCs. Kang P, Xie X, Tan Z, Yang J, Shen B, Zhou Z, Pei F. J Mater Sci Mater Med. 2015 Feb
  • Arsenic, barium, strontium and uranium geochemistry and their utility as tracers to characterize groundwaters from the Espadán-Calderona Triassic Domain, Spain. Giménez-Forcada E, Vega-Alegre M. Sci Total Environ. 2015 Apr 15
  • The deposition of strontium-substituted hydroxyapatite coatings. Boyd AR, Rutledge L, Randolph LD, Mutreja I, Meenan BJ. J Mater Sci Mater Med. 2015 Feb
  • Strontium eluting graphene hybrid nanoparticles augment osteogenesis in a 3D tissue scaffold. Kumar S, Chatterjee K. Nanoscale. 2015 Feb 7
  • Architectural control of urea in supramolecular 1D strontium vanadium oxide chains. Schwarz B, Streb C. Dalton Trans. 2015 Feb 17
  • Evaluation of injectable strontium-containing borate bioactive glass cement with enhanced osteogenic capacity in a critical-sized rabbit femoral condyle defect model. Zhang Y, Cui X, Zhao S, Wang H, Rahaman MN, Liu Z, Huang W, Zhang C. ACS Appl Mater Interfaces. 2015 Feb 4
  • Short-term effect of strontium- and zinc-containing toothpastes and mouthrinses on volatile sulphur compounds in morning breath: a randomized, double-blind, cross-over clinical study. Soares LG, Jonski G, Tinoco EM, Young A. Eur J Oral Sci. 2015 Apr
  • In vitro interactions of blood, platelet, and fibroblast with biodegradable magnesium-zinc-strontium alloys. Nguyen TY, Cipriano AF, Guan RG, Zhao ZY, Liu H. J Biomed Mater Res A. 2015 Feb 17.