The discovery of iridium is closely related to platinum and other platinum-based elements. Ancient Ethiopians and people of various cultures in South America have used naturally occurring platinum group metals since ancient times, which must contain a small amount of other platinum group elements, including iridium. /kloc-in the 0/7th century, Spanish conquerors discovered platinum in the present-day choco province of Colombia and brought it to Europe. However, it was not until 1748 that scientists discovered that it was not an alloy of any known metal, but a brand-new element.
At that time, chemists who studied platinum put platinum in aqua regia (a mixture of hydrochloric acid and nitric acid) to produce soluble salts. The prepared solution will leave a small amount of dark insoluble residue every time. Joseph Proust thinks this residue is graphite. French chemist Victor Collet de Sotil, Count Folcra Antoine Fran? ois? Ois, Earl of Fourcroy) and Louis Nicolas Vauquelin also observed this black residue in 1803, but the quantity was too small for further experiments.
1803, the British chemist Smithsonian Tennant analyzed the residue and concluded that it must contain new metal elements. Walker Lang soaked the powder back and forth in acid and alkali to obtain volatile oxides. He thought it was an oxide of a new element and named it "ptene", which originated from the Greek word "π π ν ο?" (ptènos), that is, "winged". Tennant discovered more residues and soon discovered two new elements, namely osmium and iridium. After a series of reactions involving sodium hydroxide and hydrochloric acid, he made a crimson crystal (probably Na2 [IRL6] NH2O). Many salts of iridium have bright colors, so Tennant chose Iriz, the rainbow goddess in Greek mythology. ρι? Iris), named iridium "iridium". The discovery of this element was recorded in a letter to the Royal College on June 2 1, 1804.
18 13 years, children of British chemist John George melted iridium for the first time. 1842, Robert hale obtained high-purity iridium metal for the first time. He measured the density of iridium at 265,438+0.8 g/cm, and found that this metal is almost malleable and extremely hard. 1860, Henry Aiding St. Claire de Ville and Jules Henry Debray melted iridium in large quantities for the first time. The melting process of iridium per kilogram requires more than 300 liters of pure oxygen and H2.
Iridium is difficult to melt plasticity, which greatly limits its practical application. John Isaac Hawkins invented a gold pen with an iridium nib in 1834. 1880, Holland and William loveland Dudley greatly simplified the melting process of iridium by using phosphorus, and applied for a patent in the United States. After that, Johnson & Johnson Feng Wan Company of the United Kingdom said that they began to use a similar method to melt iridium as early as 1837, and exhibited the melted iridium at many world expositions. Otto Feussner first used iridium-ruthenium alloy material in thermocouple in 1993, which enabled this new equipment to measure temperatures as high as 2000°c [7].
1957, Rudolf Mossbauer discovered that in solid metal samples containing only Ir, atoms can emit and absorb gamma rays without recoil. His experiment is one of the symbolic physics experiments in the 20th century. This phenomenon is called Mossbauer effect (other nuclei showing this effect have been discovered one after another, such as Fe), which is the central principle of Mossbauer spectroscopy and has important applications in physics, chemistry, biochemistry, metallurgy and mineralogy. Only three years after the publication of the paper, namely 196 1 year, Mossbauer won the Nobel Prize in physics for this discovery at the age of 32.