Iridium (Ir)
transition-metalSolid
标准原子量
192.217 u电子排布
[Xe] 6s2 4f14 5d7熔点
2445.85 °C沸点
4427.85 °C密度
2.25622e+4 kg/m³氧化态
−3, −2, −1, +1, +2, +3, +4, +5, +6, +7, +8, +9电负性（鲍林）
2.2第一电离能
8.96702 eV发现年份
1803原子半径
135 pm详细信息
Iridium is a very dense platinum-group transition metal with exceptional resistance to corrosion and high-temperature attack. It occurs naturally mainly with platinum-group minerals and in nickel-copper sulfide ores. Chemically it forms robust complexes, especially in oxidation states +3 and +4, and it is notable for the global iridium anomaly associated with the Cretaceous-Paleogene boundary impact layer.
Iridium, a metal of the platinum family, is white (similar to platinum) but with a slight yellowish cast. Because iridium is very hard and brittle, it is hard to machine, form, or work.
It is the most corrosion-resistant metal known, and was used in making the standard meter bar of Paris, which is a 90 percent platinum and 10 percent iridium alloy. This meter bar was replaced in 1960 as a fundamental unit of length (see Krypton).
Iridium is not attacked by any of the acids nor by aqua regia, but is attacked by molten salts, such as NaCl and NaCN. The specific gravity of iridium is to osmium's specific gravity. Calculations of the densities of iridium and osmium from the space lattices give values of 22.65 and 22.61 g/cm^3, respectively. These values may be more reliable than actual physical measurements for determining which element is heavier.
The name derives from the Latin Iris, the Greek goddess of rainbows, because of the variety of colours in the element's salt solutions. Iridium and osmium were both discovered in a crude platinum ore in 1803 by the English chemist Smithson Tennant. Iridium was discovered independently by the French chemist H. V. Collet-Descotils, who actually published his paper one month before Tennant, but Tennant is given credit for the discovery, perhaps because he alone also found osmium in the ore.
Iridium and osmium were discovered at the same time by the British chemist Smithson Tennant in 1803. Iridium and osmium were identified in the black residue remaining after dissolving platinum ore with aqua regia, a mixture of 25% nitric acid (HNO3) and 75% hydrochloric acid (HCl). Today, iridium is still obtained from platinum ores and as a by-product of mining nickel.
From the Latin word iris meaning rainbow. Tennant discovered iridium in 1803 in the residue left when crude platinum is dissolved by aqua regia. The name iridium is appropriate because its salts are highly colored.
Pure iridium is a hard, brittle, silvery-white metal with a high luster. It remains bright in air under ordinary conditions and has an unusually high melting point. Bulk metal is difficult to machine because of its hardness and brittleness.
Iridium is used where chemical durability and high-temperature strength justify its cost. Major applications include crucibles for growing oxide crystals, spark-plug electrodes, electrical contacts, and wear-resistant alloys with platinum or osmium. Iridium coatings and components are used in some aerospace and industrial equipment. Radioisotope thermoelectric generators have used ¹⁹²Ir? No; ¹⁹²Ir is chiefly a gamma source for industrial radiography and some brachytherapy, not an energy source.
Pure iridium is very brittle and is nearly impossible to machine. It is primarily used as a hardening agent for platinum. Platinum-iridium alloys are used to make crucibles and other high temperature equipment. Iridium is also alloyed with osmium to make the tips of fountain pens and compass bearings.
Iridium is the most corrosive resistant metal known. For this reason, the standard meter bar was created from an alloy of 90% platinum and 10% iridium. This bar was replaced as the definition of the meter in 1960 when the meter was redefined in terms of the orange-red spectral line of krypton-86.
A thin, worldwide layer of iridium exists in a layer of sediment that was put down at the end of the Cretaceous period. Since meteors and asteroids contain a higher percentage of iridium than the earth's crust, this iridium enriched layer is seen as evidence that the earth was struck by a large meteor or asteroid at that time. Dust from the impact would have spread around the globe, depositing the iridium. The dust also would have blocked the sun for a time, resulting in the extinction of many plant and animal species, including the dinosaurs.
Although its principal use is as a hardening agent for platinum, iridium is also used to make crucibles and devices requiring high temperatures. It is also used for electrical contacts.
The element forms an alloy with osmium which is used for tipping pens and compass bearings.
Isotopes in Industry
Metallic 192Ir (with a half-life of 74 days) is used as a radiation source in gamma cameras for non-destructive testing of products for manufacturing flaws, such as aircraft parts, boilers, and pipeline welds (Fig. IUPAC.77.1) [274] P. Hayward, D. Currie. “Radiography of welds using seleniuim 75, Ir 192 and x-rays”, in Asia-Pacific Conference on NDT, Auckland, New Zealand (2006)..
Isotopes in Medicine
Metallic 192Ir is used in brachytherapy [188] S. J. Adelstein, F. J. Manning. Isotopes for Medicine and the Life Sciences, pp. 20–25, National Academy Press, Washington DC (1995)., [521] A. Talamo, Y. Gohar. Radioactive Isotope Production for Medical Applications Using Kharkov Electron Driven Subcritical Assembly Facility, ANL-07/18, Argonne National Laboratory Argonne, Illinois (2007)., [522] S. A. Buzdar, M. A. Gadhi, M. A. Rao, N. A. Laghari, M. Anees. J. Pak. Med. Assoc.59, 113 (2009)., [523] T. Genkaa, S. Iwamotoa, E. Juitab, N. Takeuchia. Nucl. Inst. Methods Phys. Res. Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.369, 709 (1996).. 191mIr (with a half-life of 5 s) is used for blood flow imaging (angiography), especially in pediatric populations [524] K. J. Kairemo, M. S. Kestilä, S. Savolainen, O. A. Korhola, J. V. Hiltunen, R. I. Svahn, E. T. Korppi Tommola, F. F. Knapp, C. Brihaye. J. Nucl. Biol. Med.38, 86 (1994)., [525] S. T. Treves, A. B. Packard, L. C. T. Fung. J. Nucl. Med.45, 508 (2004).. The m in the superscript 191mIr indicates a metastable state of the isotope.
Isotopes Used as a Source of Radioactive Isotope(s)
Iridium consists of two stable isotopes (191Ir and 193Ir) from which the radioactive isotopes 192Ir and 195mPt (with a half-life of 4 days) can be produced. Both are used in nuclear medicine. The m in the superscript 195mPt indicates a metastable state of the isotope.
Iridium chemistry is dominated by coordination compounds and oxides rather than simple salts. Common oxidation states are +3 and +4, while lower and higher states occur in organometallic or strongly oxidizing systems. Iridium(IV) oxide, IrO₂, is an electrically conducting oxide used in dimensionally stable anodes and electrochemical research. Hexachloroiridic acid, H₂IrCl₆, and related chloroiridate salts are important refining and precursor compounds. The complex [Ir(ppy)₃] is a representative phosphorescent organoiridium emitter.
See more information at the Iridium compound page.
Massive iridium metal is chemically inert and has low acute toxicity, but finely divided powder can present dust and fire hazards. Soluble iridium salts and organoiridium compounds should be treated as potentially toxic because biological effects are compound-specific and incompletely characterized. The radionuclide ¹⁹²Ir emits penetrating gamma radiation and requires strict shielding and source control.
Iridium is extremely scarce in the crust and is usually dispersed with other platinum-group elements. Natural mobility is low because the metal and many of its minerals are resistant to weathering, although complexing ligands and industrial processing can mobilize small amounts. The sharp enrichment of iridium in some boundary clays is widely used as evidence for extraterrestrial material mixed into sediment.
Iridium is recovered chiefly as a by-product of platinum-group metal refining from nickel-copper sulfide ores and platinum placers. Supply is constrained by the production of the host metals, complex separation chemistry, and limited primary deposits. Demand is small but specialized, so substitution is possible in some electrical and catalytic uses but difficult in high-temperature crucibles and certain corrosion-resistant components. Recycling from spent electrodes, crucibles, and industrial scrap is important because the metal is rare and costly to replace.
Iridium occurs uncombined in nature with platinum and other metals of this family in alluvial deposits. It is recovered as a by-product from the nickel mining industry.
Iridium is a heavy r-process and s-process element made in late stellar evolution and explosive astrophysical environments. In the Solar System it is far more abundant in primitive meteorites than in Earth’s crust, because much of Earth’s original inventory partitioned into the core during differentiation. This siderophile behavior makes iridium a sensitive tracer of meteoritic input.
- Iridium is one of the densest elements, close to osmium in measured density.
- The name comes from Iris, reflecting the varied colors of some iridium salts.
- Iridium metal resists attack by aqua regia better than most noble metals.
- The Cretaceous-Paleogene boundary layer is enriched in iridium relative to ordinary crustal rocks.
- Iridium crucibles are used to grow some high-melting oxide crystals.
- Natural iridium consists mainly of the stable isotopes ¹⁹¹Ir and ¹⁹³Ir.
图片
性质
物理性质
- 原子半径（经验值）
- 135 pm 比较所有元素的原子半径（经验值） →
- 共价半径
- 141 pm 比较所有元素的共价半径 →
- 范德华半径
- 202 pm 比较所有元素的范德华半径 →
- 金属半径
- 127 pm 比较所有元素的金属半径 →
- 密度
- 2.25622 × 104 kg/m³ 比较所有元素的密度 →
- 摩尔体积
- 0.00854 L/mol
- 标准温度和压力下的物相
- 固态 比较所有元素的标准温度和压力下的物相 →
- 熔点
- 2445.85 °C 比较所有元素的熔点 →
- 沸点
- 4427.85 °C 比较所有元素的沸点 →
- 热导率
- 147 W/(m·K) 比较所有元素的热导率 →
- 比热容
- 0.131 J/(g·K) 比较所有元素的比热容 →
- 摩尔热容
- 25.1 J/(mol·K) 比较所有元素的摩尔热容 →
- 晶体结构
- 面心立方 比较所有元素的晶体结构 →
化学性质
- 电负性（鲍林）
- 2.2 比较所有元素的电负性（鲍林） →
- 电负性（Allen）
- 1.68
- 电子亲和能
- 1.565 eV
- 第一电离能
- 8.96702 eV 比较所有元素的第一电离能 →
- 第二电离能
- 17.000059 eV 比较所有元素的第二电离能 →
- 第三电离能
- 28.000096 eV 比较所有元素的第三电离能 →
- 第四电离能
- 40.000138 eV 比较所有元素的第四电离能 →
- 第五电离能
- 57.000196 eV 比较所有元素的第五电离能 →
- 氧化态
- −3, −2, −1, +1, +2, +3, +4, +5, +6, +7, +8, +9 比较所有元素的氧化态 →
- 价电子
- 9 比较所有元素的价电子 →
- 电子排布
- [Xe] 6s2 4f14 5d7
热力学性质
- 熔化热
- 0.27050837 eV 比较所有元素的熔化热 →
- 汽化热
- 6.26004 eV 比较所有元素的汽化热 →
- 升华热
- 6.944085 eV
- 原子化热
- 6.944085 eV
- 原子化焓
- 6.93372 eV
核性质
- 质子
- 77 比较所有元素的质子 →
- 中子
- 116 比较所有元素的中子 →
- 已知同位素
- 43 比较所有元素的已知同位素 →
- 稳定同位素
- 2 比较所有元素的稳定同位素 →
- 最稳定同位素
- Ir-193
- 发现年份
- 1803
丰度
- 丰度（地壳）
- 0.001 mg/kg 比较所有元素的丰度（地壳） →
晶体结构
- 晶格常数a
- 384 pm
电子结构
- 各电子层电子数
- 2, 8, 18, 32, 15, 2 比较所有元素的各电子层电子数 →
标识符
- CAS登记号
- 7439-88-5 比较所有元素的CAS登记号 →
- 谱项符号
- 4F9/2
- InChI
- InChI=1S/Ir
- InChI Key
- GKOZUEZYRPOHIO-UHFFFAOYSA-N
电子排布 实测值
Ir: 4f¹⁴ 5d⁷ 6s²[Xe] 4f¹⁴ 5d⁷ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d⁷ 6s²原子模型
不同同位素的中子数、质量和稳定性不同，但中性原子的电子排布不变。
原子模型示意图，未按比例绘制。
原子指纹
发射 / 吸收光谱
同位素分布
| 质量数 | 原子质量（u） | 天然丰度 | 半衰期 |
|---|---|---|---|
| 191 稳定 | 190.9605893 ± 0.0000021 | 37.3000% | 稳定 |
| 193 稳定 | 192.9629216 ± 0.0000021 | 62.7000% | 稳定 |
物相 / 状态
原因: 低于熔点（2445.85 °C）2420.8 °C
示意图，未按比例绘制
相变点
相变能
在熔点熔化1 mol物质所需的能量
在沸点汽化1 mol物质所需的能量
在升华点升华1 mol物质所需的能量
密度
标准条件下
标准条件下
原子光谱
已显示10项，共77项。 按离子电荷升序排列。
收录能级 ?
| 离子 | 电荷 | 能级 |
|---|---|---|
| Ir I | 0 | 231 |
| Ir II | +1 | 76 |
| Ir III | +2 | 2 |
| Ir IV | +3 | 224 |
| Ir V | +4 | 2 |
| Ir VI | +5 | 2 |
| Ir VII | +6 | 2 |
| Ir VIII | +7 | 2 |
| Ir IX | +8 | 2 |
| Ir X | +9 | 2 |
离子半径
| 电荷 | 配位 | 自旋 | 半径 |
|---|---|---|---|
| +3 | 6 | 暂无 | 68 pm |
| +4 | 6 | 暂无 | 62.5 pm |
| +5 | 6 | 暂无 | 56.99999999999999 pm |
化合物
同位素 (2)
| 质量数 | 原子质量（u） | 天然丰度 | 半衰期 | 衰变方式 | |
|---|---|---|---|---|---|
| 191 稳定 | 190.9605893 ± 0.0000021 | 37.3000% ± 0.2000% | 稳定 | stable | |
| 193 稳定 | 192.9629216 ± 0.0000021 | 62.7000% ± 0.2000% | 稳定 | stable |
谱线
| 波长（nm） | 强度 | 电离级 | 类型 | 跃迁 | 准确度 | 来源 | |
|---|---|---|---|---|---|---|---|
| 382.7577 nm | 58 | Ir II | emission | 5d7.(2D2).6s 3D → 5d7.(4F<5/2>).6p (5/2,1/2)* | 实测值 | NIST | |
| 384.593 nm | 暂无 | Ir II | emission | 5d7.(2G).6s 1G → 5d7.(4F<9/2>).6p (9/2,3/2)* | 实测值 | NIST | |
| 387.3624 nm | 9 | Ir II | emission | 5d6.6s2 5D → 5d7.(4P<5/2>).6p (5/2,1/2)* | 实测值 | NIST | |
| 389.558 nm | 暂无 | Ir II | emission | 5d6.6s2 5D → 5d7.(4F<7/2>).6p (7/2,1/2)* | 实测值 | NIST | |
| 395.1973 nm | 暂无 | Ir II | emission | 5d6.6s2 5D → 5d7.(4F<9/2>).6p (9/2,1/2)* | 实测值 | NIST | |
| 395.2882 nm | 8 | Ir II | emission | 5d7.(2H).6s 3H → 5d6.6s.(6D<9/2>).6p (9/2,1/2)* | 实测值 | NIST | |
| 397.882 nm | 6 | Ir II | emission | 5d7.(2F).6s 3F → 5664* | 实测值 | NIST | |
| 398.6377 nm | 5 | Ir II | emission | 5d6.6s2 5D → 5d7.(4F<3/2>).6p (3/2,1/2)* | 实测值 | NIST | |
| 399.0389 nm | 6 | Ir II | emission | 5d6.6s2 3H → 6197* | 实测值 | NIST | |
| 400.1961 nm | 12 | Ir II | emission | 5d7.(2D2).6s 3D → 5d7.(4P<5/2>).6p (5/2,1/2)* | 实测值 | NIST | |
| 402.5321 nm | 4 | Ir II | emission | 5d7.(2F).6s 3F → 5d6.6s.(6D<5/2>).6p (5/2,1/2)* | 实测值 | NIST | |
| 402.5399 nm | 29 | Ir II | emission | 5d7.(2D2).6s 3D → 5d7.(4F<7/2>).6p (7/2,1/2)* | 实测值 | NIST | |
| 404.1381 nm | 45 | Ir II | emission | 5d7.(2H).6s 3H → 5d7.(4F<9/2>).6p (9/2,1/2)* | 实测值 | NIST | |
| 404.4911 nm | 7 | Ir II | emission | 5d7.(2F).6s 3F → 5d7.(4F<9/2>).6p (9/2,3/2)* | 实测值 | NIST | |
| 410.8315 nm | 48 | Ir II | emission | 5d7.(2F).6s 3F → 5d7.(4F<5/2>).6p (5/2,1/2)* | 实测值 | NIST | |
| 411.7209 nm | 3 | Ir II | emission | 5d7.(2G).6s 3G → 5d7.(4F<9/2>).6p (9/2,1/2)* | 实测值 | NIST | |
| 412.8911 nm | 17 | Ir II | emission | 5d7.(2P).6s 3P → 5d7.(4P<1/2>).6p (1/2,1/2)* | 实测值 | NIST | |
| 413.91 nm | 21 | Ir II | emission | 5d7.(2P).6s 3P → 5d7.(4F<9/2>).6p (9/2,3/2)* | 实测值 | NIST | |
| 439.0196 nm | 4 | Ir II | emission | 5d6.6s2 5D → 5d7.(4P<5/2>).6p (5/2,1/2)* | 实测值 | NIST | |
| 443.3888 nm | 暂无 | Ir II | emission | 5d7.(2F).6s 3F → 5d6.6s.(6D<7/2>).6p (7/2,1/2)* | 实测值 | NIST | |
| 454.5672 nm | 暂无 | Ir II | emission | 5d7.(2H).6s 3H → 5d7.(4F<9/2>).6p (9/2,1/2)* | 实测值 | NIST | |
| 461.1752 nm | 暂无 | Ir II | emission | 5d7.(2F).6s 3F → 5d7.(4P<5/2>).6p (5/2,1/2)* | 实测值 | NIST | |
| 467.5844 nm | 5 | Ir II | emission | 5d7.(2G).6s 3G → 5d7.(4F<9/2>).6p (9/2,1/2)* | 实测值 | NIST | |
| 479.5262 nm | 暂无 | Ir II | emission | 5d6.6s2 5D → 5d7.(4F<9/2>).6p (9/2,1/2)* | 实测值 | NIST |
扩展性质
共价半径（扩展）
- 共价半径（Pyykkö）
- 122 pm
- 共价半径（Pyykkö，双键）
- 115 pm
- 共价半径（Pyykkö，三键）
- 107 pm
范德华半径
- Batsanov
- 200 pm
- Alvarez
- 241 pm
- UFF
- 284 pm
- MM3
- 236 pm
原子半径与金属半径
- 原子半径（Rahm）
- 240 pm
- 金属半径（C12）
- 136 pm
编号标度
- Mendeleev
- 65
- Pettifor
- 65
- Glawe
- 62
电负性标度
- Ghosh
- 0
- Miedema
- 6
- Gunnarsson–Lundqvist
- 6
- Robles–Bartolotti
- 6
极化率与色散
- 偶极极化率
- 54 a.u.
- 偶极极化率（不确定度）
- 7 a.u.
- C₆ (Gould–Bučko)
- 522 Ha·Bohr6
Miedema参数
- Miedema摩尔体积
- 8.52 cm3/mol
- Miedema电子密度
- 6
供应风险与经济性
- 生产集中度
- 60
- 相对供应风险
- 8
- 储量分布
- 95
- 政治稳定性（最大生产国）
- 44
- 政治稳定性（最大储量国）
- 44
相变与同素异形体
| 熔点 | 2719.15 K |
| 沸点 | 4701.15 K |
氧化态分类
高级参考数据
屏蔽常数 (14)
| n | 轨道 | σ |
|---|---|---|
| 1 | s | 1.4881 |
| 2 | p | 4.4624 |
| 2 | s | 20.1102 |
| 3 | d | 13.514 |
| 3 | p | 21.9311 |
| 3 | s | 22.7942 |
| 4 | d | 37.2628 |
| 4 | f | 38.6552 |
| 4 | p | 35.086 |
| 4 | s | 34.152 |
晶体半径详情 (3)
| 电荷 | CN | 自旋 | rcrystal (pm) | 来源 |
|---|---|---|---|---|
| 3 | VI | 82 | estimated, | |
| 4 | VI | 76.5 | from r^3 vs V plots, | |
| 5 | VI | 71 | estimated, from metallic oxides, |
同位素衰变方式 (64)
| 同位素 | 模式 | 强度 |
|---|---|---|
| 163 | p | — |
| 164 | p | — |
| 164 | A | — |
| 164 | B+ | — |
| 165 | p | — |
| 165 | A | — |
| 166 | A | 93% |
| 166 | p | 7% |
| 167 | A | 43.5% |
| 167 | p | 38.6% |
X射线散射因子 (515)
| 能量 (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 2.22753 |
| 10.1617 | — | 2.30683 |
| 10.3261 | — | 2.38895 |
| 10.4931 | — | 2.474 |
| 10.6628 | — | 2.56207 |
| 10.8353 | — | 2.65417 |
| 11.0106 | — | 2.75003 |
| 11.1886 | — | 2.84935 |
| 11.3696 | — | 2.94781 |
| 11.5535 | — | 3.0118 |
补充数据
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
1×10-3 milligrams per kilogram
参考文献 (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
参考文献 (1)
Sources
Sources of this element.
Iridium occurs uncombined in nature with platinum and other metals of this family in alluvial deposits. It is recovered as a by-product from the nickel mining industry.
参考文献 (1)
- [6] Iridium https://periodic.lanl.gov/77.shtml
参考文献
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Iridium.
The element property data was retrieved from publications.