- Electrical properties of GaSe prepared by an indirect gas-phase method
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An indirect method has been developed for the synthesis of GaSe. Single crystals have been obtained from the gas phase, and some their electrical properties have been investigated.
- Geidarov
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- Pentamethylcyclopentadienylgallium (Cp*Ga): Alternative synthesis and application as a terminal and bridging ligand in the chemistry of chromium, iron, cobalt, and nickel
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An alternative synthetic route to η5-pentamethylcyclopentadienylgallium (Me5C5Ga, Cp*Ga, 1) via reductive dehalogenation of (pentamethylcyclopentadienyl)diiodogallane (Cp*GaI2, 2) is reported. In addition, the behavior of compound 1 as a ligand in transition metal chemistry is examined. In the reaction of 1 with Cr(CO)5(C8Hi14) (C8H14 = ciscyclooctene), Fe2(CO)9, Fe(CO)3CHT (CHT = cycloheptatriene), Co2(CO)8, and Ni(CO)4 the new complexes Cr(Cp*Ga)(CO)5 (3), Fe(CP*Ga)(CO)4 (4), Fe2(μ-Cp*Ga)3(CO)6 (5), Co2(μ-Cp*Ga)2(CO)6 (6), and Ni4(μ-Cp*Ga)4(CO)6 (8), respectively, were obtained. They were characterized by analytical and spectroscopic methods; solid-state structures were determined by X-ray diffraction analysis. In the reaction of 1 with Ni(CO)4, the complex Ni(Cp*Ga)-(CO)3 (7) is an intermediate, which was characterized by IR and NMR data. The η5-bonding mode within the Cp*Ga ligand is maintained, apart from one Cp*Ga unit in 5 which exhibits η3/η1-bonding. The cone angle of η5-Cp*Ga is 112°, as determined on the basis of structural data of 3 and 4. Concerning the σ-donor/π-acceptor properties, 1 is classified as a predominant electron donor.
- Jutzi, Peter,Neumann, Beate,Reumann, Guido,Stammler, Hans-Georg
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- Design of p-T-x diagrams for gallium chalcogenides with the use of an ancillary component
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A new null-gage method has been developed to study p-T-x diagrams of binary systems with low-fugacity compounds. This method consists of measuring the equilibrium vapor pressure, created by the selective interaction of a third (ancillary) component with one of the components of a test sample, as a function of temperature. Iodine and chlorine (in the form of GaHaI3) were used to study Ga-Se and Ga-S phase diagrams. At temperatures up to about -1080 K, the GaSe homogeneity range is 0.12 ± 0.04 mol % and is displaced to gallium. Gallium monosulfide has a narrower homogeneity range comparable to the error in composition determination (0.04 mol %). The Ke values have been calculated as a function of temperature for heterogeneous equilibria of condensed gallium chalcogenides and gallium halides, as well as the partial gallium vapor pressure of solid gallium selenides and gallium sulfides. For the equilibrium of GaSe, Ga2Se3, and vapor, the gallium partial pressure has been shown to be independent of an ancillary component. The results have been used to calculate the thermodynamic parameters for gallium chalcogenides.
- Zavrazhnov
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p. 1577 - 1590
(2008/10/09)
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- Gas Transport in the Ga-Se-I System and the Possibility of Controlled Synthesis of Gallium Selenides
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The processes of chemical transport in the Ga-Se-I system are investigated. It is found that the starting GaSe disproportionates when the temperature difference has a critical value of ΔT. The possibility of controlling the composition of gallium selenide samples in the GanSem(S)-Ga(1)-V(Gal+GaI3) system is demonstrated. The processes investigated, which permit one to control the composition of low-volatility compounds, can be expanded to other systems.
- Zavrazhnov,Turchen,Goncharov,Prigorodova
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- Nonstoichiometric Phases with Low Volatility. Homogeneity Area in the Ga-Se System
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A new approach to the phase nonstoichiometry and microphase diagrams of binary systems with nonvolatile compounds based on addition of a third volatile component was developed. The feasibility of this approach was demonstrated by the example of nonstoichiometry in the Ga-Se system using gallium triiodide as the third component. The homogeneity area in this system has nearly ≈0.2 at % width and is shifted to the cation-excess range.
- Zavrazhnov,Turchen,Goncharov,Fedorova,Suvorov
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p. 870 - 875
(2007/10/03)
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- Composition of the Vapor Phase and Equilibria in the Ga-Se-I System
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With a zero diaphragm gauge, the temperature dependences of the equilibrium constants were determined for the equilibria GaI3 = GaI +I2, 2GaI3 = Ga2I6, 2Ga(liquid) + GaI3(gas) = 3GaI(gas), 2Ga(from Se solution in Ga) + GaI3(gas) = 3GaI(gas), and GaI3(gas) + 6GaSe(solid) = 3GaI(gas) + 2Ga2Se3(solid). It was shown that only GaI and GaI3 occur in noticeable amounts in the vapor phase in the heterophase equilibria studied. The GaI3 reaction with GaSe to form GaI and Ga2Se3 commences at temperatures higher than those for the GaI3 reactions with liquid gallium or a selenium solution in gallium.
- Zavrazhnov,Turchen,Goncharov,Sharov
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p. 1270 - 1274
(2008/10/08)
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- Mass-spectrometric study of gallium chloroiodides and their adducts with pyridine
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A sample with the GaCl2I empirical formula was obtained by the iodination of combined gallium dichloride.By means of mass spectrometry mixed monomeric halides were shown to predominate in the vapor.Dimeric forms of halides are absent from the vapor.The ap
- Kaplun, M. M.,Timoshkin, A. Yu.,Suvorov, A. V.,Misharev, A. D.
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p. 488 - 490
(2007/10/03)
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- X-ray structure, EPR, and magnetic susceptibility of gallium(III) tris(3,5-di-tert-butyl-1,2-semibenzoquinonate), a main group triradical complex
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The compound Ga(TBSQ?)3 (TBSQ? = 3,5-di-tert-butyl-1,2-benzosemiquinonate anion) has been prepared by two synthetic routes and its structure determined by X-ray analysis. The crystals are rhombohedral, with a = 16.408(6) ?, c = 13.898(4) ?, V = 3240(2) ?3, Z = 3, and space group R3(h); R = 0.050; T = 23°C. The molecule has a distorted octahedral GaO6 kernel, with bidentate TBSQ?- ligands. The compound and its solutions in noncoordinating solvents are stable for months, even when exposed to air. Frozen solution EPR spectra display evidence for the thermal occupation of both quartet, S = 3/2, and doublet, S = 1/2, states. A triradical should have both states, and comparison of theoretical simulations of the triradical EPR spectrum with the experimental spectrum reveals that the energy separation of the quartet and two doublet states is greater than 0.8 cm-1 and less than 20 cm-1. Ga(TBSQ?)3 reacts with pyridine to give Ga(TBSQ?)(TBC)(py)2 (TBC = 3,5-di-tert-butylcatecholate dianion). Magnetic susceptibility was measured for solid Ga(TBSQ?)3 from 2 to 296 K and for the toluene solution at 296 K. The low-temperature susceptibilities show that the ground state is the doublet states of the triradical, and the high-temperature susceptibilities can only be explained by postulating another thermally accessible doublet state, which is close in energy to the triradical states. This state is postulated to be Ga(TBSQ?)(TBC)(TBQ) (TBQ = 3,5-di-tert-butyl-1,2-benzoquinone).
- Ozarowski, Andrzej,McGarvey, Bruce R.,El-Hadad, Ahmed,Tian, Zhigang,Tuck, Dennis G.,Krovich, Daniel J.,DeFotis, Gary C.
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p. 841 - 847
(2008/10/08)
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- Sinthesis and High-Pressure Behaviour of Quaternary Chalcogenide Halides M2M'X3Y (M = Zn, Cd; M' = Al, Ga, In; X = Se, Te; Y = Cl, Br, I)
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Quaternary chalcogenide halides M2M'X3Y (M = Zn, Cd; M' = Al, Ga, In; X = Se, Te; Y = Cl, Br, I) can be synthesized by heating stoichiometric amounts of the binary components MX, MY2, and M'2X3 in evacuated sealed quartz ampoules.In the case of aluminium and gallium compounds, a mixture of the M' and X elements rather than the binary compounds has been used.The products are typical tetrahedral compounds, crystallizing with either the defect wurtzite-type or the defect zinc-blende-type structure.At 25 kbar, and 1400 deg C, Cd2InSe3Cl, Cd2InSe3Br, and Cd2InSe3I transform from the defect wurtzite-type structure to quenchable high-pressure phases with defect NaCl-type structure.The retransformation to the ambient-pressure phases proceeds via intermediates having the defect zinc-blende-type structure.Some aspects of the apparent nonstoichiometry in the high-pressure phases are discussed. - Keywords: Quaternary Chalcogenide Halides, Synthesis, Crystal Structure, High-Pressure Reactions
- Range, Klaus-Juergen,Handrick, Karin
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p. 153 - 158
(2007/10/02)
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