Crystalline–amorphous transitions of Ge–Se alloys by mechanical grinding

Tani, Yasuo; Shirakawa, Yoshiyuki; Shimosaka, Atsuko; Hidaka, Jusuke

doi:10.1016/s0022-3093(01)00788-8

Cited by 24 publications

(22 citation statements)

References 6 publications

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“…The amorphous Ge 4 Se 5 (which cannot be obtained by liquid quenching) also has the 4-2 folded structure, although its composition is nearer to GeSe. Such a crystalline-amorphous transition of Ge-Se alloys by mechanical milling has also been investigated by Tani et al 206 The mechanisms for amorphization of Se are suggested to be based on the distortion between helical chains connected by van der Waals forces. Monoclinic GeSe 2 is amorphized by disordering of the bonds between the connected tetrahedra.…”

Section: Elements and Alloysmentioning

confidence: 94%

Hallmarks of mechanochemistry: from nanoparticles to technology

et al. 2013

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The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).

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Section: Elements and Alloysmentioning

confidence: 94%

Hallmarks of mechanochemistry: from nanoparticles to technology

et al. 2013

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“…One of them is the difficulty in obtaining information about atomic structures, which define the short-range order (SRO) of the alloy. In this context, the structures of amorphous Ge x Se 1−x (a-Ge x Se 1−x ) and liquid Ge x Se 1−x (l-Ge x Se 1−x ), in particular Ge 33 Se 67 (GeSe 2 ), have been extensively studied by several experimental techniques, like neutron diffraction (ND) 1,2,3,4,5 , x-ray diffraction (XRD) 6,7 , extended x-ray absorption fine structure (EXAFS) 8,9 and Raman spectroscopy (RS) 10,11,12 . On the theoretical side, molecular dynamics simulations (MD) 13,14,15,16,17,18,19,20,21 and reverse Monte Carlo (RMC) simulations 7 have been carried out to understand the SRO in these liquids and glasses in terms of two possible and distinct models.…”

Section: Introductionmentioning

confidence: 99%

“…In our case, an unexpected large number of Se-Se pairs is found in the first coordination shell, suggesting that the tetrahedral units are linked by Se-Se "bridges". Takeuchi et al 10 , by comparing the structures of a-Ge 30 Se 70 produced by MQ and by vacuum evaporation (VE) techniques, and Tani et al 6 studying the a-GeSe 2 produced by Mechanical Grinding (MG) of its crystalline counterpart have also found some structural differences among alloys produced by different methods. These differences are important because some physicochemical properties can be altered and improved as desired by choosing an appropriate preparation method.…”

Section: Introductionmentioning

confidence: 99%

Reverse Monte Carlo simulations and Raman scattering of an amorphous GeSe4 alloy produced by mechanical alloying

Machado

Lima

Campos

et al. 2005

Solid State Communications

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The short and intermediate range order of an amorphous GeSe4 alloy produced by Mechanical Alloying were studied by Reverse Monte Carlo simulations of its x-ray total structure factor and Raman scattering. The simulations were used to compute the G RMC Ge-Ge (r), G RMC Ge-Se (r) and G RMC Se-Se (r) partial distribution functions and the S RMC Ge-Ge (K), S RMC Ge-Se (K) and S RMC Se-Se (K) partial structure factors. We calculated the coordination numbers and interatomic distances for the first and second neighbors and the bond-angle distribution functions Θ ijl (cos θ). The data obtained indicate that the structure of the alloy has important differences when compared to alloys prepared by other techniques. There are a high number of Se-Se pairs in the first shell, and some of the tetrahedral units formed seemed to be connected by Se-Se bridges.

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“…2,9 Then, one needs to explain why the properties of the aged glass are determined by the only rigid newly formed Ge-rich network, but not a superposition of both Ge-and Se-rich parts. Moreover, calorimetric T g for the as-milled amorphous Se predominantly built of polymeric Se n -chains is higher than for the as-quenched Se composed of mixed Se 8 ring molecules and polymeric Se n -chains, [17][18][19] while an opposite trend in T g is attributed by Dash et al 2 to the effect of Se 8 crown molecules in Se-rich Ge-Se glasses. Additional argument comes from the fact, that formation of Se 8 crowns in supercooled liquid regime is thermodynamically favorable and irreversible process.…”

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confidence: 85%