Large displacement of germanium atoms in crystalline Ge2Sb2Te5

Shamoto, S.; Yamada, Noboru; Matsunaga, Toshiyuki; Proffen, Thomas; Richardson, J. W.; Chung, Jaiho; Egami, T.

doi:10.1063/1.1861976

Cited by 58 publications

(42 citation statements)

References 17 publications

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“…Moreover, in general terms, when a material is submitted to compression, its Raman bands decrease in intensity and the linewidth increases. This is understood mainly as a consequence of the disorder introduced by the compression [25,26]. So, we can understand that some disorder is being introduced in the sample due to the compression.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Joya

Barba-Ortega

Raba-Páez

et al. 2017

Metals

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Abstract:In this work, a set of nanoparticles of Nb 2 O 5 nanoparticles were grown by both the Pechini and the sol-gel methods. The amorphous materials were calcined at 650 • C or at 750 • C. X-ray diffraction, scanning electron microscopy, luminescence and Raman spectroscopy were used in order to characterize the materials. From the study, it is possible to state that the method of production of nanoparticles, beyond the temperature of synthesis, has a great influence on whether the phase produced is hexagonal or orthorhombic. Additionally, compared to de Sol-gel method, the Pechini method produced samples with smaller particle sizes. The photoluminescence spectra of niobium pentoxide nanostructure materials show that the emission peaks are positioned between 334 to 809 nm and there is a change of intensity which varies depending on the synthesis route used. High pressure Raman spectra at room temperature were obtained from two samples grown by the sol-gel method. Up to 6 GPa, where it is possible to observe the Raman bands, no modification other than the increase of disorder was observed, and this can be associated with a change of phase.

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Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Joya

Barba-Ortega

Raba-Páez

et al. 2017

Metals

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“…The main advantage of the liquid phase is that it can be produced in large quantities for phase-change alloys, while the amorphous state, due to the necessity of extremely high quenching rates, can only be obtained in small quantities without extreme measures. [29] In addition, our findings demonstrate that the structure of the liquid phase provides useful information on the suitability of a chalcogenide as a phase-change material. These conclusions call for further experiments, to study the detailed atomic arrangement in the liquid state.…”

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confidence: 94%

Characteristic Ordering in Liquid Phase‐Change Materials

et al. 2008

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The structure of molten elemental (Si, Ge) or binary (III-V, II-VI) semiconductors is well known, and has been shown to depend on the average number of valence s-and p-electrons (N sp ) [1] However, studies on binary systems have been limited to stoichiometric compounds, corresponding to a discrete set of N sp values. Studying ternary compounds allows us to investigate homogeneous liquids with varying average valenceelectron numbers. These materials have the additional advantage of often having lower melting temperatures, which renders them experimentally feasible for studies in an accessible temperature range. Among these ternary systems, a subset of Sb-and Te-based alloys shows a unique combination of properties. On the one hand, their electrical resistivity and optical reflectivity change dramatically with the transition between amorphous and crystalline states, indicating significant structural differences between these two phases. On the other hand, re-crystallization of the amorphous phase using laser or current pulses at temperatures between the glass transition (T g ) and melting (T m ) temperatures is fast, and proceeds in less than 10 ns. These properties are used in phase-change memories, [2,3] with a number of suitable materials for optical and electronic phase-change storage having been identified by trial and error.

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“…Currently, we can see that the superior phase-change properties of the GeSbTe alloys are largely due to the highly inclusive crystalline structure. Concerning the details of this NaCl-like phase, several new aspects have been proposed mainly relating to the dislocation of Ge atoms from the lattice site [13][14][15]. It will be important for clarifying the rapid phasechange mechanism of this material system.…”

Section: Crystallization Propertiesmentioning

confidence: 99%

Origin, secret, and application of the ideal phase‐change material GeSbTe

Yamada

2012

Physica Status Solidi (b)

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Discovery of the GeSbTe phase‐change alloy in particular along the GeTe–Sb2Te3 tie‐line took place in the mid‐1980s. The amorphous alloys showed ideal properties, for example, high thermal stability at r.t. and laser‐induced rapid crystallization with large optical changes. Thereafter, GeSbTe was successively applied to various optical disks such as DVDs and BDs. Through DSC and XRD analyses, the appearance of the metastable phase having a NaCl‐type structure was observed over a wide compositional region. This was the “key” to realizing the ideal phase‐change properties. During this year, the role of the constituent elements of Ge and Sb became clear by RMC modeling using AXS data at SPring‐8, where the “nucleation dominant crystallization process” was well explained. magnified imageThe aspect of the latest Blu‐ray Disc (BD) product of Panasonic: GeSbTe phase‐change films are utilized in every recording layer. It is seen that the front‐side recording layers, L1 and L2, are highly transparent.

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Large displacement of germanium atoms in crystalline Ge2Sb2Te5

Cited by 58 publications

References 17 publications

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Characteristic Ordering in Liquid Phase‐Change Materials

Origin, secret, and application of the ideal phase‐change material GeSbTe

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