Single Crystals Of Ga Research Articles

Crystal Growth, composition, structure, and Raman spectroscopy of novel Ga,Ge-rich topaz

Single crystals of Ga-, Ge-, and Ga,Ge-rich (up to 41.42 wt% GeO2 and 33.95 wt% Ga2O3 or 0.98 apfu (atom per formula unit) Ge and 0.90 apfu Ga) and undoped topazes were grown on natural topaz seeds as a newly overgrown layer up to 5 mm thick. The thermogradient hydrothermal method was used at a temperature range of 600 − 650 °C and a pressure of 100 MPa under the condition of reverse temperature solubility factor of silica and alumina in the fluoride solution. The chemical composition and crystal structure of the grown topazes, as well as the distribution of gallium and germanium in the overgrown layer, were investigated by electron microprobe analysis (EMPA), single crystal X-ray diffraction (SCXRD) and Raman spectroscopy. The overgrown layers of Ge-, and Ga,Ge-rich topazes have a zonal distribution of elements, two zones corresponding to topaz Al2SiO4(F,OH)2 and krieselite (Al,Ga)2GeO4(F,OH)2 compositions are distinguished. The structural and spectroscopic studies show linear dependences of unit cell parameters and Raman shift on germanium and gallium contents and confirm the existence of a complete series of topaz-krieselite solid solution.

Tossing and Turning: Guests in the Flexible Frameworks of Metal(III) Dicarboxylates

Single crystals of Ga(OH)(C(8)H(4)O(4)).0.74C(8)H(6)O(4) (2) and Ga(OH,F)(C(8)H(4)O(4)).0.74C(8)H(6)O(4) (3) were obtained under hydrothermal conditions. The structures of 2 and 3 have the same topological framework as the previously reported aluminum 1,4-benzenedicarboxylate (BDC), Al(OH)(C(8)H(4)O(4)).0.7C(8)H(6)O(4) (1). The frameworks are built by interconnecting M-OH-M chains (M = Al, Ga) with BDC anions to form large diamond-shaped one-dimensional channels filled with additional H(2)BDC guest molecules occupying disordered positions in the channels. Upon removal of H(2)BDC, other guest molecules such as H(2)O and pyridine can be inserted. In this work, we present a study of the intercalation of aromatic guests (BDC and pyridine) into frameworks of 1-3 by liquid and vapor diffusion into the empty channels of 1 and by single-crystal-to-single-crystal solvothermal guest exchange for 2 and 3. In the case of Al(OH)BDC and Ga(OH,F)BDC, two interconvertible, guest-concentration-dependent phases with different orientations of the pyridine guests have been observed, while only one pyridine orientation is found in Ga(OH)BDC.

Czochralski growth of Ga 1−xIn xSb single crystals with uniform compositions

Severe macrosegregation tends to develop along Ga 1− x In x Sb alloy crystals grown by the conventional Czochralski process. Failure to eliminate macrosegregation by floating-crucible Czochralski has been attributed to InSb back diffusion from the floating crucible. In the present study Ga 1− x In x Sb crystals were grown from the growth melt in a floating crucible having a unique bottom tube that was wide to let the replenishing melt in the outer crucible pass through easily but long to suppress back diffusion. Ga 1− x In x Sb crystals with a uniform composition of 1 mol% InSb were grown as targeted. However, crystals of about 2 mol% InSb were grown when 4 mol% InSb was targeted. By using Bi 1− x Sb x as a model material, it was found that hydrodynamic instability caused the problem—the denser growth melt mixed with the lighter replenishing melt during or even before crystal growth. A new double-crucible Czochralski process was thus developed, with an upper chamber for the growth melt and a lower chamber for the replenishing melt. The slightly higher gas pressure in the lower chamber caused replenishing through a long capillary tube that suppressed mixing between the melts. Single crystals of Ga 1− x In x Sb were grown with uniform compositions up to 4.5 mol% InSb.

Strukturbestimmung von Ga[GaCl4] und α-Ga[GaBr4] nach Kristallisation aus Halogenbenzolen / Structure Determination of Ga[GaCl4] and α-Ga[GaBr4] Crystallized from Halobenzene Solvents

Single crystals of Ga[GaCl4] and α-Ga[GaBr4] have been obtained by crystallization from chlorobenzene and bromobenzene, respectively. The crystal structures of the two compounds, determined previously only on the basis of photographic data, were refined to a more satisfactory level of accuracy. The results confirm the presence of tetrahedral GaX4 - anions as thecounterions to dodecahedrally coordinated Ga+ cations. The gallium-halogen distances in these dodecahedral arrays fall into four classes, thus resulting in a significant asymmetry of the Ga(I) center. This deviation from ideal S4 symmetry is also apparent in the 69Ga NMR spectra of the crystalline powder samples. Approximate calculation of the data leads to asymmetry parameters (η) of 0.44 and 0.27 for the chloride and bromide, respectively. Crystal data Ga[GaCl4]: Pnna (#52), a = 7.200(1), b = 9.625(1), c = 9.498(1) Å; Z = 4. For α-Ga[GaBr4]: Pnna, a = 7.528(1), b = 9.972(1), c = 10.010(1) Å, Z = 4.

Deviations from Matthiessen's rule in gallium and other polyvalent metals

Data for oriented single crystals of Ga are presented and compared with previous results for Al and In. Striking similarities suggest that a common mechanism is responsible for the behaviour of resistivity in all three materials.

Vapor transport growth of Ga 2−xFe xO 3 crystals

Single crystals of Ga 2−xFe xO 3 up to 6 mm. on edge were grown by chemical transport with HCl. Chlorine transported multi-phase products, while no transport occurred with either I 2 or HBr. Seeded crystal growth runs were successful, and the quality of the crystals appeared to be better than in unseeded runs.