7440-56-4

Basic information

• Product Name: Germanium
• Synonyms: Germaniumelement
• CAS NO: 7440-56-4
• Molecular Formula: GeH₂
• Molecular Weight: 72.59
• EINECS: 231-164-3
• Mol File: 7440-56-4.mol
• Article Data: 127

Chemical Properties

• Melting Point: 937℃
• Boiling Point: 2830 ºC
• Appearance: greyish-white lustrous brittle solid
• Density: 5.35 g/cm³
• CAS DataBase Reference: Germanium(CAS DataBase Reference)
• NIST Chemistry Reference: Germanium(7440-56-4)
• EPA Substance Registry System: Germanium(7440-56-4)

Safety Data

• Hazard Codes: F:Flammable;;
• Statements: R11:; R36/38:
• Safety Statements: S2:; S26:
• Hazardous Substances Data: 7440-56-4(Hazardous Substances Data)

Usage

General Description

Germanium is a chemical element represented by the symbol Ge and atomic number 32. It is categorized as a metalloid and is notable for its semiconductive properties. Germanium is brittle and has a silvery-white appearance. It is mainly used in the manufacturing of electronics and solar panels due to its semiconductive nature. It is also found in fiber-optic systems and infrared optics. Discovered in 1886 by Clemens Winkler, it was named after Germany. It is not particularly abundant and is mostly extracted from sphalerite zinc ores, while smaller amounts can be obtained from silver, lead, and copper ores. The element is mostly harmless but in large amounts, germanium dust can cause lung damage if inhaled.

InChI:InChI=1/Ge

Upstream product

• 5764-65-8 3,4-dimethyl-1,1-dichlorogermacyclopent-3-ene 
• 2875-92-5 phenylgermane 
• 7782-65-2 germane 
• 78-10-4 tetraethoxy orthosilicate 
• 7732-18-5 water 
• 14165-55-0 tetraethoxygermanium 
• 7439-95-4 magnesium 
• 13450-92-5 germanium tetrabromide 
• 7440-23-5 sodium 
• 7440-19-9 samarium 
• 16940-66-2 sodium tetrahydroborate 
• 1333-74-0 hydrogen 
• 12025-22-8 NbGe_0.15 
• 1747-99-5 ethylgermane 

Downstream Products

• 7439-89-6 iron 
• 13573-08-5 GeI₂ 
• 13450-95-8 germanium tetraiodide 
• 24415-00-7 dibromogermylene 
• 13450-92-5 germanium tetrabromide 
• 1184-77-6 dimethyldiiodogermane 
• 1111-91-7 triiodomethylgermane 
• 21110-21-4 germanium monochloride 
• 10060-11-4 germanium dichloride 
• 10038-98-9 germaniumtetrachloride 
• 21572-18-9 trichloro(chloromethyl)germane 
• 12775-96-1 copper 
• 7783-58-6 germanium tetrafluoride 
• 10102-43-9 nitrogen(II) oxide 

Relevant articles and documents

Low temperature growth of single crystalline germanium nanowires

Ge nanowires have been prepared at a low temperature by a simple hydrothermal deposition process using Ge and GeO2 powders as the starting materials. These as-prepared Ge nanowires are single crystalline with the diameter ranging from 150 nm to 600 nm and length of several dozens of micrometers. The photoluminescence spectrum under excitation at 330 nm shows a strong blue light emission at 441 nm. The results of the pressure and GeO2 content dependences on the formation and growth of Ge nanowires show that the hydrothermal pressure and GeO2 content play an essential role on the formation and growth of Ge nanowires under hydrothermal deposition conditions. The growth of Ge nanowires is proposed as a solid state growth mechanism.

Synthesis of crystalline and amorphous germanium nanorods

Crystalline and amorphous germanium nanorods have been synthesized by PVD of germanium powders in flowing Ar/H2 atmospheres. TEM images show diameters of the nanorods ranging from 20 to 200 nm and length up to 5 μm. Selected area electron diffraction indicates that the crystalline nanorods have tetragonal structure. Their growth process has been considered as VLS mechanism. Published by Elsevier Science Ltd.

SiF4-Sensitized Decomposition of GeH4 by a Pulsed CO2 TEA Laser1,2

The decomposition of GeH4, sensitized by multiphoton absorption of unfocused infrared laser radiation by SiF4, has been studied in the fluence range 0.2-0.9 J/cm2 and over a total pressure range of 1-70 Torr.Strong absorption of energy from a pulser CO2 laser photon field (P40 line; 1027.4 cm-1) and subsequent energy-transfer processes cause an increase in the temperature of the system.As a result of these processes, decomposition of GeH4 occurs leading to the formation of stoichiometric amounts of metallic germanium and molecular hydrogen.The effects of initial composition, pressure, fluence, and presence of foreign gases (He, H2) on the yield of GeH4 decomposition were examined.A reaction model is proposed which assumes that molecules initially present in the absorption volume are heated by the laser pulse and subsequently decompose unimolecularly.Since the decomposition process is exothermic, it prompts a futher increase in temperature and thus enhances the decomposition process.Both absorption and decomposition create a shock wave causing expansion of hot gas into cool surrounding volume.The latter process brings about cooling of the hot gas and quenches the decomposition process.Taking into account the above-mentioned effects the temperature profiles (T versus time and geometry of the reaction zone) were evaluated on the basis of statistical thermodynamics, assuming that, at any stage, the system attains thermal equilibrium.Yields of decomposition were then derived with kuni values calculated by the RRKM method.The proposed approach accounts satisfactorily for the experimentally observed dependencies, and we believe it can be generally applied to the description of photosensitized process in the infrared region.

On direct-writing methods for electrically contacting GaAs and Ge nanowire devices

The electronic transport and gating characteristics in GaAs and Ge nanowires (NWs) are altered significantly following either indirect or direct exposure to a focused Ga+ ion beam (FIB), such as that used to produce Pt electrical contacts to NWs. While these results challenge the assumptions made in some previously reported work relating to the electronic properties of semiconductor NWs using FIB-assisted production of contacts and/or their leads, local electron beam induced deposition is shown to be a reliable and facile route for producing robust electrical contacts to individual vapor phase-grown NWs in a manner that enables study of their actual carrier transport properties.

Influence of defects and interface on radiative transition of Ge

The influences of defects and surface roughness on the indirect bandgap radiative transition of Ge were studied. Bulk Ge has 15 times the integrated intensity of photoluminescence of Ge-on-Si. However, for Ge-on-Si sample, the direct transition related ph

Application of n-dodecyltrimethylammonium chloride for the oxidation of intermetallic phases

The thermal decomposition products of ionic liquids based on n-dodecyltrimethylammonium chloride (DTAC) were used for the preparation of the metastable allotrope Ge(cF136) by oxidation of Na12Ge17 in gas-solid reactions. This method of preparation provides a promising low-temperature route for the synthesis of intermetallic phases and elemental modifications. In order to explore the reaction mechanism, we investigated the thermal decomposition of DTAC as well as of the ionic liquids DTAC/MgCl 2 and DTAC/AlCl3 by in-situ mass spectrometry and by powder X-ray diffraction. The results have revealed HCl, CH3Cl and 1-chlorododecane to act as oxidizing agents in the gas-solid redox reactions.

HIGH-PRESSURE SYNTHESIS AND CRYSTAL STRUCTURE OF VGe2 AND Cr4Ge7.

The new germanides, Cr//4Ge//7 with the defect disilicide-type structure and VGe//2 with the C40 structure, are synthesized at 4-5. 5 GPa and 800-1100 degree C for 1-3 hr using the belt-type high-pressure apparatus. The relationship between the chemical c

Influence of surface states on electron transport through intrinsic Ge nanowires

Solution-grown single-crystal Ge nanowires were used as conductive channels in field effect transistor devices to study the influence of surface states on their electron transport properties. Nanowires contacted with Pt electrodes using focused ion beam metal deposition exhibited linear current-voltage (IV) curves at room temperature with apparent resistivities ranging from 101 to 10-1 ? cm. In all cases, the nanowire conductance decreased with positive external electric fields applied perpendicular to the nanowire surface by a gate electrode, characteristic of p-type carrier accumulation at the nanowire surface. The field-induced change in conductance exhibited a time-dependent relaxation, with response time and magnitude of current decrease that depended on the nanowire surface chemistry. Nanowires treated with an organic passivation layer using a thermally initiated hydrogermylation reaction exhibited 2 orders of magnitude slower current relaxation and a smaller decrease in current relative to bare nanowires with oxidized surfaces. ? 2005 American Chemical Society.

Ba8Ge43 revisited: A 2a′x2a′x2a′ superstructure of the clathrate-I type with full vacancy ordering

The reinvestigation of the crystal structure of Ba8Ge 43□3 (space group Ia3d, no. 230; a = 21.3123(5) A; Z = 8; Pearson symbol cI408) shows a full ordering of the vacancies (□) in the germanium framework. This ordered crystal structure can be considered as a derivative of an ideal Ba8Ge46 clathrate-I type structure (Pm3n, a′ = a/2) in which three Ge vacancies (per formula unit) are allowed to order in a cubic superstructure with a doubled unit cell parameter (□ at the 24c site, space group Ia3d). In the resulting Ge framework, each vacancy □ is surrounded by four three-bonded (3b)Ge - species. The ordering in crystals of as-cast samples (cooled in argon atmosphere, non-annealed) is partially disrupted. For the as-cast crystals, a short-range model is proposed based on the partial distribution of Ge on the 24c and 24d sites. From the electron balance, Ba8Ge43 can be considered as a metallic Zintl phase with four excess electrons per formula unit. The Ba8Ge43 phase is stable in the temperature range 770-810°C and exists in equilibrium with Ba6Ge25 and Ge. By decomposition of undercooled (metastable) Ba8Ge43, a new metastable binary BaGe ～5 phase is formed.

Peculiarities of thermal decomposition of inorganic and organometallic compounds of GeIV and GeII. Thermolysis of (acac) 2GeX2 (X = Cl, N3) and (CO) 5MGeCl2(thf) (M = Cr, Mo, W)

Thermal decomposition of the complexes (acac)2Ge(N 3)2 (1), (acac)2GeCl2 (2), and (CO)5M=GeCl2(THF) (M = Cr (3), Mo (4), W (5)) was studied by differential scanning calorimetry a

Synthesis, structural characterization, and thermal properties of the first germanium N,N,N′,N′-tetraalkylguanidinates

The first examples of germanium N,N,N′,N′- tetraalkylguanidinates have been prepared, and two of them have been structurally characterized. All of them exihibit high stability and volatility. Their potential as low-temperature precursors for MOCVD of Ge a

Growth of germanium nanowires using liquid GeCl4 as a precursor: The critical role of Si impurities

Liquid GeCl4 precursors have been employed to grow into one dimensional Ge nanowires (NWs) via a vapor-liquid-solid (VLS) process, in which Si, supplied as a form of liquid SiCl4, plays a critical role for the successful formation of Ge NWs. The Royal Society of Chemistry 2009.

Fast and safe synthesis of micron germanium in an ammonia atmosphere using Mo2N as catalyst

Here, we reported a new method for fast and safe synthesis of a micron germanium (Ge) semiconductor. The Ge was successfully prepared from mixed GeO2 with a low amount of MoO3 by the NH3 reduction method at 800 °C for an ultra-short time of 10 min. XRD patterns show that the Ge has a tetragonal structure. SEM images show that the size of the Ge particles is from 5 μm to 10 μm, and so it is on the micron scale. UV-visible diffuse reflectance spectroscopy shows that the Ge has good light absorption both in the ultraviolet and visible regions. The formation of Ge mainly goes through a two-step conversion in the NH3 flow. Firstly, GeO2 is converted to Ge3N4, and then Ge3N4 is decomposed to generate Ge. The comparison experiments of MoO3 and Mo2N demonstrate that Mo2N is the catalyst for the Ge synthesis which improves the Ge3N4 decomposition. The presented fast and safe synthesis method of Ge has great potential for industrialization and the proposed Mo2N boosting the Ge3N4 decomposition has provided significant guidance for other nitride decomposition systems.

Synthesis and photoluminescent properties of size-controlled germanium nanocrystals from phenyl trichlorogermane-derived polymers

We report the preparation of luminescent oxide-embedded germanium nanocrystals (Ge-NC/ GeO2) by the reductive thermal processing of polymers derived from phenyl thchlorogermane (PTG, C6H 5-GeCl3). Sol-gel processing of PTG yields air-stable polymers with a Ge:O ratio of 1:1.5, (C6H5GeO 1.5)n, that thermally decompose to yield a germanium rich oxide (GRO) network. Thermal disproportionation of the GRO results in nucleation and initial growth of oxide-embedded Ge-NC, and subsequent reaction of the GeO2 matrix with the reducing atmosphere results in additional nanocrystal growth. This synthetic method affords quantitative yields of composite powders in large quantities and allows for Ge-NC size control through variations of the peak thermal processing temperature and reaction time. Freestanding germanium nanocrystals (FS-Ge-NC) are readily liberated from Ge-NC/GeO2 composite powders by straightfoward dissolution of the oxide matrix in warm water. Composites and FS-Ge-NC were characterized using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX), and photoluminescence (PL) spectroscopy.

HIGH-PRESSURE SYNTHESIS AND ELECTRICAL AND MAGNETIC PROPERTIES OF MnGe AND CoGe WITH THE CUBIC B20 STRUCTURE.

MnGe and CoGe with the cubic B20 structure were synthesized at 4-5. 5 GPa and 600-1000 degree C for 1-3 hr using the belt-type high-pressure apparatus. Both MnGe and CoGe are antiferromagnetic with Neel temperatures of 197 and 120 K, respectively. One expects an electron transfer of 0. 7 electron from germanium to transition metal in these compounds. The anomalous temperature dependences of the electrical resistivity, the thermoelectric power, and the magnetic susceptibility of MnGe and CoGe are due to a 'temperature-induced local moment. '

Concentration-dependent size control of Germanium nanocrystals

A room temperature solution phase preparation of germanium nanocrystals has been examined by means of varying the germanium precursor concentration. By varying the germanium tetrachloride concentration, it is possible to control the size distribution of nanocrystals formed. Copyright

Electrochemical preparation of germane

Germane has been prepared through the electrochemical reduction of the germanate anion in alkaline solutions with a current efficiency of 40-45%. Active solution circulation in the cathodic zone and the use of an Sn or Cd cathode are shown to raise the germane yield. The current density and initial solution concentration have a weak effect on the reduction process.

GROWTH AND ETCHING OF GERMANIUM FILMS BY CHEMICAL VAPOR DEPOSITION IN A GeCl4-H2 GAS SYSTEM.

The etching and growth of germanium films are investigated using a GeCl//4-H//2 gas system in the temperature range of 490 degree -565 degree C. At relatively low GeCl//4 partial pressures less than 2 multiplied by 10** minus **3 torr, epitaxial growth of Ge is observed on Ge (100) surfaces, whereas at GeCl//4 partial pressures higher than 2 multiplied by 10** minus **3 torr, etching of the Ge film is found to occur. In the experiments utilizing patterned substrates, where the surface consists of defined areas of Ge and SiO//2, Ge is found to deposit selectively only on the exposed Ge regions. The growth reactions of Ge epitaxial films proceed through the Langmuir-Hinshelwood mechanism: the surface reaction takes place between two hydrogen atoms dissociatively adsorbed and a surface-adsorbed GeCl//2 molecule.

RF-sputter deposition of Zn-Ge nitride thin films

Nitride Zn-Ge thin films were deposited by reaction sputtering. Black conducting (Zn1-xGex)3N2+δ with x≤0.27 was obtained in a compositional range below 29 wt% Ge against the total metal content. Greenish pale yellow ZnGeN2 was observed in a range of 30-60 wt% Ge. This crystallized in a hexagonal lattice of a comparable size to the isoelectronic GaN. Its solid solution range seems to be very narrow and its band gap was estimated to be about 3.1 eV. Ge3N4, like amorphous (Ge1-yZny)3N4-y with y≤0.43 films, shows pale yellow color above the compositional range of 60 wt% Ge.

Reactivity and Controlled Redox Reactions of Salt-like Intermetallic Compounds in Imidazolium-Based Ionic Liquids

Substituted imidazolium ionic liquids (ILs) were investigated for their reactivity towards Na12Ge17 as a model system containing redox-sensitive Zintl cluster anions. The ILs proved widely inert for imidazolium cations with a 1,2,3-trisubstitution at least by alkyl groups, and for the anion bis(trifluoromethylsulfonyl)azanide (TFSI). A minute conversion of Na12Ge17 observed on long-time contact with such ILs was not caused by dissolution of the salt-like compound, and did thus not provide dissolved Ge clusters. Rather, a cation exchange led to the transfer of Na+ ions into solution. In contrast, by using benzophenone as an oxidizer, heterogeneous redox reactions of Na12Ge17 were initiated, transferring a considerable part of Na+ into solution. At optimized conditions, an X-ray amorphous product NaGe6.25 was obtained, which was thermally convertible to the crystalline type-II clathrate Na24–δGe136 with almost completely Na-filled polyhedral cages, and α-Ge. The presented method thus provides unexpected access to Na24–δGe136 in bulk quantities.

Size-tunable germanium particles prepared by self-sustaining reduction of germanium oxide

Here, we report on a size-controlled synthesis of highly crystalline germanium particles, via the self-sustained reaction of GeO2 with Zn, Mg, and NaBH4. The thermodynamic analysis suggests that the GeO2 + 2Zn and GeO2 + NaBH4 systems are characterized by moderate heats of reaction (?121 and ?204 kJ per mole of Ge, respectively), while GeO2 + 2Mg exhibits a much higher reaction enthalpy (?623 kJ). Magnesium reduction has been found not to be suitable for the preparation of germanium crystals due to the high reaction temperature, which exceeds 2000 °C. The partial substitution of Zn by Mg, however, enables increasing the overall reaction temperature in the low caloric GeO2 +Zn system. By using different reducers and their mixtures, the reaction temperature was optimized to be in the 600–1100 °C range. Such temperature modifications allow for control of the germanium particle sizes, ranging from 200 nm to 2 mm. Thermal analysis of the reacting mixtures and electron microscopy examination of the products indicates that dissolution-precipitation is the dominant formation mechanism of the germanium crystals in the GeO2 + Zn system. The higher reaction temperatures in the GeO2 + Zn + Mg and GeO2 + NaBH4 systems cause melting, and subsequent coalescence of the primarily precipitated germanium resulting in much larger particles.