Synthesis and Structures of Gallium‐β‐Diketiminate Complexes: Isolation of a Dinuclear Gallium(II) Complex

The sterically demanding β‐diketiminate ligand L^dmp [L^dmp = HC{(CMe)N(dmp)}₂, dmp = C₆H₃‐2,6‐Me₂] was used to stabilize various gallium complexes in the formal oxidation states +II and +III. The reaction of in situ generated [L^dmpLi] with gallium chloride affords [L^dmpGaCl₂] ( 1 ), which was used as starting complex to synthesize a variety of gallium(III) compounds [L^dmpGaX₂] [X = F ( 2 ), I ( 3 ), H ( 4 ), and Me ( 5 )]. Synthesis of the dinuclear complex [L^dmpGaI]₂ ( 6 ), with gallium in the formal oxidation state +II was accomplished by converting “GaI” with in situ generated [L^dmpLi] in toluene. All compounds were characterized by elemental analyses, NMR spectroscopy, LIFDI‐TOF‐MS, and single‐crystal X‐ray diffraction. Additionally DFT calculations were performed for analysis of the bonding in 6 .     

Coordination modes of 2-mercapto-1,3-benzothiazolate in gallium and indium complexes

2-Mercapto-1,3-benzothiazole (mbztH) may act as a chelating or bridging ligand. In this study, reactions of mbztH with Me₃Ga and Me₃In were examined. The products were characterized by NMR spectroscopy, elemental analyses, melting point, and molecular weight determinations. Formation of mononuclear chelating complexes Me₂M(mbzt) (M = Ga, In) was observed in solutions. Crystallization of Me₂M(mbzt) yielded uncommon non-symmetrical dinuclear complexes Me₄M₂(mbzt)₂, in which one metal is bonded to two sulfurs and the other to two nitrogens.     

Novel surface molecularly imprinted material modified multi-walled carbon nanotubes as solid-phase extraction sorbent for selective extraction gallium ion from fly ash

A new gallium (Ga(III)) ion-imprinted multi-walled carbon nanotubes (CNTs) composite sorbent was synthesized by a surface imprinting technique. The Ga(III) ion-imprinted/multi-walled carbon nanotubes (Ga(III)-imprinted/CNTs) sorbent was characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), nitrogen adsorption experiment, static adsorption experiment, and solid-phase extraction (SPE) experiment. The effects of sample volume, sample pH, washing and elution conditions on the extraction of Ga(III) ion from real sample were studied in detail. The imprinted sorbent offered a fast kinetics for the adsorption of Ga(III). The maximum static adsorption capacity of the imprinted sorbent towards was 58.8 μmol g⁻¹. The largest selectivity coefficient for Ga(III) in the presence of Al(III) was over 57.3. Compared with non-imprinted sorbent, the imprinted sorbent showed good imprinting effect for Ga(III) ion, the imprinting factor (α) was 2.6, the selectivity factor (β) was 2.4 and 2.9 for Al(III) and Zn(II), respectively. The developed imprinted SPE method was applied successfully to the detection of trace Ga(III) ion in fly ash samples with satisfactory results.     

How light affects 5,10,15-tris(pentafluorophenyl)corrole

5,10,15-Tris(pentafluorophenyl)corrole slowly undergoes oligomerization when left in solution at room temperature, under air and ambient light. This transformation was studied in different solvents (chloroform, dichloromethane, and toluene) and the main resulting products were identified as the 3,3′-corrole dimer 2a and the 3,3′,17′,3′′-corrole trimer 3a.     

Structural stability and electronic structure of iron adsorption on the GaN(0 0 0 1) surface

In this work, we have investigated by means of first-principles spin-polarized calculations, the electronic and magnetic properties of iron (Fe) adsorption and diffusion on the GaN(0 0 0 1) surface using density functional theory (DFT) within a plane-wave pseudopotential scheme. In the surface adsorption study, results show that the most stable positions of a Fe adatom on GaN(0 0 0 1) surface are the H3 sites and T4 sites, for low and high Fe coverage respectively. We found that the Fe-H3 2 × 2 surface reconstruction exhibits a half-metallic behavior with a spin band gap and stable ferromagnetism ordering, which is a desirable property for high-efficiency magnetoelectronic devices. In addition, confirming previous experimental results, we found that the iron monolayers present a ferromagnetic order and a large thermal stability. This is interesting from a theoretical point of view and for its technological applications.     

Movement of liquid gallium dispersing low concentration of temperature sensitive magnetic particles under magnetic field

In this work, a temperature sensitive functional fluid was synthesized, and then its movement under the influence of magnetic field was investigated. Silica coated FeNbVB particles, prepared by chemical synthesis, were dispersed into liquid gallium, because they have a relatively high magnetization and a high temperature dependency. The synthesized functional fluid (solid fraction of 0.3 mass%) showed temperature dependence for magnetization within the testing temperature range between 298 and 353 K. The movement of gallium based fluid under the influence of the magnetic field with a magnetic field gradient was observed at various temperatures. We found that at 318 K, fluid displacement of the synthesized functional fluid is better when compared with the fluid displacement at 348 K.     

Fabrication of a freestanding GaN layer by direct growth on a ZnO template using hydride vapor phase epitaxy

A new hydride vapor phase epitaxy (HVPE)-based approach for the fabrication of freestanding GaN (FS-GaN) substrates was investigated. For the direct formation of low-temperature GaN (LT-GaN) layers, the growth parameters were optimized: the polarity of ZnO, the growth temperature, and the V/III ratio. The FS-GaN layer was achieved by gas etching in an HVPE reactor. A fingerprint of Zn out-diffusion was detected in the photoluminescence measurements, especially for the thin (80 μm) FS-GaN film; however, a thicker film (400 μm) was effectively reduced by optimization of GaN growth.     

Ca3N2 as a flux for crystallization of GaN

In this work Ca₃N₂ was investigated as a potential flux for crystallization of GaN. Melting temperature of the potential flux at high N₂ pressure evaluated by thermal analysis as 1380 °C is in good agreement with the theoretical prediction. It is shown that Ca₃N₂ present in the liquid gallium in small amount (1 at%) dramatically accelerates synthesis of GaN from its constituents. On the other hand, it does not influence significantly the rate of GaN crystallization from solution in gallium in temperature gradient for both unseeded and seeded configurations. However the habit and color of the spontaneously grown GaN crystals change drastically. For 10 mol% Ca₃N₂ content in the liquid Ga it was found that the GaN thick layer and GaN crystals (identified by micro-Raman scattering measurements) were grown on the substrate. For growth from molten Ca₃N₂ (100%) with GaN source, the most important observations were (i) GaN source material was completely dissolved in the molten Ca₃N₂ flux and (ii) after experiment, GaN crystals were found on the sapphire substrate.     

In-situ observations of dissolution process of GaSb into InSb melt by X-ray penetration method

Dissolution process of GaSb into InSb melt was observed by an X-ray penetration method. The intensity of X-rays penetrated through the rectangular shaped GaSb (seed)/InSb/GaSb (feed) sandwich sample was recorded by the CdTe line sensor detector. The penetrated X-ray intensities and images of the sample were obtained as a function of time and temperature. The gallium (Ga) composition profile of the sample was calculated as a function of time by making the calibration line with the penetrated X-ray intensities of GaSb and InSb standard samples. The calculated Ga composition profile of the grown sample agreed well with the data measured by energy dispersive X-ray spectroscopy analysis. The result suggested that lower GaSb seed dissolved faster than upper GaSb feed despite of the low temperature at the lower GaSb seed. It clearly indicates that the solutal transport induced by gravity strongly affects the dissolution process.