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Elemental Semiconductors
Published in Lev I. Berger, Semiconductor Materials, 2020
The existence of germanium was predicted by D.I. Mendeleev (1871), who named the still unknown element as eka-silicon and described the chemical properties it must have. It was first isolated (1887) by Clemens A. Winkler from a silver ore (argyrodite, AggGeS6 in the form of the sulfide GeS2.3.297 The atomic number of germanium is 32 and its atomic weight is 72.61. Germanium consists of five stable isotopes, Ge70, Ge71, Ge74, Ge76, and Ge78. Electron configuration (ground state) is 4s24p2. Ionization energies for Ge0 → Ge+ → Ge2+ → Ge3+ are 8.13, 15.95, 34.22, and 45.70 eV, respectively.
Heavy Metals
Published in Abhik Gupta, Heavy Metal and Metalloid Contamination of Surface and Underground Water, 2020
Germanium (Ge) with an atomic number of 32, an atomic mass of 72.640, and a density of 5.32 g cm–3 is a silvery-white, brittle metalloid. Most of the germanium today is extracted from the zinc ore sphalerite. Germanite or copper iron germanium sulfide [CuS·FeS·GeS2] and argyrodite or silver germanium sulfide (Ag8GeS6) are the other important but rare ores containing germanium. Germanium is a semiconductor and was earlier used as a transistor after doping with arsenic and gallium. Currently, the major use of germanium is in camera and microscope lenses. Elemental germanium and germanium oxide are used in infrared spectroscopes. It is also used as an alloying agent (Encyclopaedia of Occupational Health and Safety 2012).
Ferroelastic phase transition in Cu6PS5Br1-xClx mixed crystals
Published in Phase Transitions, 2019
M. M. Luchynets, V. I. Studenyak, V. Yu. Izai, Yu. V. Minets, I. P. Studenyak, A. Kežionis
Cu6РS5X (X = Br, Cl) superionic conductors belong to the compounds with argyrodite crystal structure [1,2]. They are characterized by high electrical conductivity and low activation energy values [1–3]. At room temperature Cu6РS5X (X = Br, Cl) crystals belong to the cubic crystal system ( space group) [1]. At low temperatures two phase transitions (PTs) occur in Cu6РS5Br crystal: a ferroelastic PT at TII = (268±2) K and a superionic PT at TI = (166–180) K [4]. At the ferroelastic PT the crystal system changes from cubic ( space group) to monoclinic (Cc space group) whereas at the superionic PT no changes of such kind are observed. It should be noted that in Cu6РS5Cl a superionic and ferroelastic PT from cubic () to monoclinic (Сс) structure is observed at 170 K [5]. Optical properties and PTs in Cu6РS5X (X = Br, Cl) crystals as well as in the mixed crystals on their base were studied in Refs. [2,6–9].
A Review on Germanium Resources and its Extraction by Hydrometallurgical Method
Published in Mineral Processing and Extractive Metallurgy Review, 2021
Thi Hong Nguyen, Man Seung Lee
Germanium (Ge) was discovered by Freiberg in 1885 and isolated from mineral argyrodite (Ag8GeS6) in 1886 by chemist Clemens Winkler (Ruiz, Sola and Palmerola 2018). The oxidation states of Ge are +2 and +4 but GeO2 and GeCl4 are common forms of germanium compounds. Ge does not exist in the free state and is found in some minerals with a concentration of 0.0007% in the Earth's crust. Ge has a metallic character in a number of physical properties. Ge acts as a semiconductor in pure metallic form and is transparent to most infrared light spectrum in crystal form, and has a high refractive index in glass form (Curtolo, Friedrich and Friedrich 2017). Therefore, the optical properties of pure GeCl4 lead to its industrial application for the equipment used to detect infrared radiation. GeO2 is used as a component of glass for optical fiber devices such as cameras and microscope objectives (Hernández-Expósito et al. 2006). In addition, Ge is applied in transistors and components for electronic devices such as rectifiers and photocells. Generally, GeCl4, GeO2 and metallic germanium are the three main products of germanium (Melcher and Buchholz 2012). In terms of usage, the applications of Ge are classified into five main categories such as polymerization catalysts, fiber-optic systems, infrared optics, electronic/solar applications and other minor uses (Curtolo, Friedrich and Friedrich 2017; Höll, Kling and Schroll 2007; Lee 2018). The worldwide end-use pattern of Ge in 2010 was estimated to be as follows: 30% of infrared optics, 25% of fiber-optic systems, 25% of polymerization catalyst, 15% of electronic/solar application and 5% of phosphors, metallurgy and chemotherapy (Curtolo, Friedrich and Friedrich 2017).
On the occurrence of gallium and germanium in the Bergslagen ore province, Sweden
Published in GFF, 2019
Germanium, in turn, was originally discovered in 1886 as a major constituent of the silver-rich mineral argyrodite (ideally Ag8GeS6) from Freiberg, Germany, and was later determined by several workers as a minor component in a number of sulphide minerals, and particularly in sphalerite, from different deposits (Doelter & Leitmeier 1926; Papish 1928, and references therein).