Investigation of Phase Transitions in Stacked GeTe/SnTe and Ge2Se3/SnTe Chalcogenide Films

Phase transitions in stacked GeTe/SnTe and Ge2Se3/SnTe thin layers for potential phase-change memory applications have been investigated by X-ray diffraction using an area detector system and by scanning electron microscopy. The as-deposited underlying GeTe or Ge2Se3 layer is amorphous, whereas the top SnTe layer is crystalline. In GeTe/SnTe stack, the crystallization of GeTe phase occurs near 170°C, and upon further heating, GeTe phase disappears, followed by the formation of rocksalt-structured GexSn1-xTe solid solution. In Ge2Se3/SnTe stack, the phase transition starts with the separation of SnSe phase due to the migration of Sn ions into the Ge2Se3 layer. The migration of Sn ions and the formation of SnSe are believed to facilitate the crystallization of Ge2Se3 solid solution at ~360°C, which is much lower than the crystallization temperature of Ge2Se3, therefore consuming less power during the phase transition.

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Investigation of Phase Transition in Stacked Ge-Chalcogenide/SnTe Phase-change Memory Films

MRS Proceedings ◽

10.1557/proc-1056-hh11-70 ◽

2007 ◽

Vol 1056 ◽

Author(s):

Feiming Bai ◽

Surendra Gupta ◽

Archana Devasia ◽

Santosh Kurinec ◽

Morgan Davis ◽

...

Keyword(s):

Phase Transition ◽

Solid Solution ◽

Phase Change ◽

Phase Change Memory ◽

Thin Layers ◽

X Ray Diffraction ◽

X Ray ◽

Area Detector ◽

Memory Applications ◽

Change Memory

ABSTRACTPhase transitions in stacked GeTe/SnTe and Ge2Se3/SnTe thin layers for potential phase-change memory applications have been investigated by X-ray diffraction using a two-dimensional area detector system. The as-deposited underlying GeTe or Ge2Se3 layer is amorphous, whereas the top SnTe layer is crystalline. In the GeTe/SnTe stack, the crystallization of GeTe phase occurs near 170°C, and upon further heating, the GeTe phase disappears, followed by the formation of rocksalt-structured GexSn1−xTe solid solution. In the Ge2Se3/SnTe stack, the phase transition starts with the separation of a SnSe phase due to the migration of Sn ions into the Ge2Se3 layer. SnSe is believed to facilitate the crystallization of Ge2Se3-SnTe solid solution at ∼360°C, which is much lower than the crystallization temperature of Ge2Se3, therefore consuming less power during the phase transition.

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Structural-phase transition in (Cu2Te)2−x(ZnTe)x at high temperature

International Journal of Modern Physics B ◽

10.1142/s0217979221501137 ◽

2021 ◽

pp. 2150113

Author(s):

H. B. Gasimov ◽

R. M. Rzayev

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

High Temperature ◽

Single Crystals ◽

Structural Phase ◽

X Ray Diffraction ◽

X Ray ◽

Temperature Range ◽

Xrd Study ◽

Xrd Method

Cu2Te single crystal was grown by the Bridgman method. X-ray diffraction (XRD) study of Cu2Te single crystals in the temperature range of 293–893 K was performed and possible phase transitions in the mentioned range of temperature have been investigated. (Cu2Te)[Formula: see text](ZnTe)[Formula: see text] single crystals also were grown with [Formula: see text], 0.05, 0.10 concentrations and structural properties of the obtained single crystals were investigated by the XRD method in the temperature range 293–893 K. Lattice parameters and possible phase transitions in the mention temperature range were determined for (Cu2Te)[Formula: see text](ZnTe)[Formula: see text] single crystals for [Formula: see text], 0.05, 0.10 concentrations.

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X-ray diffraction and Raman study of DL-alanine at high pressure: revision of phase transitions

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768112028972 ◽

2012 ◽

Vol 68 (4) ◽

pp. 412-423 ◽

Cited By ~ 24

Author(s):

Nikolay A. Tumanov ◽

Elena V. Boldyreva

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Structural Phase ◽

Group Symmetry ◽

Second Phase ◽

Structural Phase Transitions ◽

X Ray Diffraction ◽

X Ray ◽

Cell Parameters ◽

Raman Study

The effect of pressure on DL-alanine has been studied by X-ray powder diffraction (up to 8.3 GPa), single-crystal X-ray diffraction and Raman spectroscopy (up to ∼ 6 GPa). No structural phase transitions have been observed. At ∼ 1.5–2 GPa, cell parameters b and c become accidentally equal to each other, but the space-group symmetry does not change. There is no phase transition between 1.7 and 2.3 GPa, contrary to what has been reported earlier [Belo et al. (2010). Vibr. Spectrosc. 54, 107–111]. The presence of the second phase transition, which was claimed to appear within the pressure range from 6.0 to 7.3 GPa (Belo et al., 2010), is also argued. The changes in the Raman spectra have been shown to be continuous in all the pressure ranges studied.

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Characterization of CdCrTe Layers Obtained by Pulsed Laser Deposition

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.203-204.193 ◽

2013 ◽

Vol 203-204 ◽

pp. 193-197

Author(s):

Piotr Sagan ◽

Volodymyr Popovych ◽

Mariusz Bester ◽

Marian Kuzma

Keyword(s):

Solid Solution ◽

Electron Diffraction ◽

Lattice Constant ◽

Pulse Length ◽

Pulsed Laser ◽

Thin Layers ◽

Laser Deposition ◽

X Ray Diffraction ◽

X Ray

In this paper we have obtained CdCrTe thin layers by PLD method using the YAG:Nd3+ laser with pulse length 250μs. Synthesized CdCrTe solid solution with 50% at. of Cr has been taken as a target. The layers were deposited on KCl substrate. The target and films were analyzed using X-ray diffraction, TEM microscope and THEED electron diffraction. The morphology of the layers are homogenous. However, we have detected several crystallographic phases: cubic CdTe, hexagonal Cr and hexagonal Te. From the measurements of lattice constant of the layer, their composition was determined to be x=0,14

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β-cubic phase transition of scandia-doped zirconia solid solution: Calorimetry, x-ray diffraction, and Raman scattering

Journal of Applied Physics ◽

10.1063/1.1471576 ◽

2002 ◽

Vol 91 (10) ◽

pp. 6493 ◽

Cited By ~ 40

Author(s):

Hirotaka Fujimori ◽

Masatomo Yashima ◽

Masato Kakihana ◽

Masahiro Yoshimura

Keyword(s):

Phase Transition ◽

Solid Solution ◽

Raman Scattering ◽

Solution Calorimetry ◽

Cubic Phase ◽

X Ray Diffraction ◽

X Ray

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Single Crystal X-Ray Diffraction Study of the Phase Transitions in Graphite-Bromine Intercalation Compounds

MRS Proceedings ◽

10.1557/proc-20-15 ◽

1982 ◽

Vol 20 ◽

Cited By ~ 2

Author(s):

D. Ghosh ◽

D.D.L. Chung

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Diffraction Study ◽

Structure Characteristic ◽

Q Value ◽

X Ray Diffraction ◽

X Ray ◽

Stage 4 ◽

Commensurate Phase ◽

Bromine Vapor

ABSTRACTReported here is the first observation of an incommensurate-commensurate phase transition at 316 ± 1 K upon heating stage-2 graphite-bromine prepared in bromine liquid. The transition during heating involved the movement of the 300 reflection toward a lower q value and the sharpening of the 010 reflection, thereby resulting in the commensurate structure characteristic of stage-2 prepared in bromine vapor. The transition was reversible. The previously reported comtmensurate-incommensurate transition occurred at 326, 329, 332, 338 and 348 K for stage 2 (in bromine liquid), stage 2 (in bromine vapor), stage 3, stage 4, and desorbed material, respectively. Disordering was observed upon completion of this transition.

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Inorganic Anion Regulates the Phase Transition in Two Organic Cation Salts Containing [(4-Nitroanilinium)(18-crown-6)]+ Supramolecules

10.20944/preprints201706.0102.v1 ◽

2017 ◽

Author(s):

Yuan Chen ◽

Yang Liu ◽

Binzu Gao ◽

Chuli Zhu ◽

Zunqi Liu

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Variable Temperature ◽

Structural Phase ◽

High Temperature Phase ◽

Temperature Phase ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Space Group ◽

X Ray

Two novel inorganic–organic hybrid supramolecular assemblies, namely, (4-HNA)(18-crown-6)(HSO4) (1) and (4-HNA)2(18-crown-6)2(PF6)2(CH3OH) (2) (4-HNA = 4-nitroanilinium), were synthesized and characterized by infrared spectroscopy, single X-ray diffraction, differential scanning calorimetry (DSC), and temperature-dependent dielectric measurements. The two compounds underwent reversible phase transitions at about 255 K and 265 K, respectively. These phase transitions were revealed and confirmed by the thermal anomalies in DSC measurements and abrupt dielectric anomalies during heating. The phase transition may have originated from the [(4-HNA)(18-crown-6)]+ supramolecular cation. The inorganic anions tuned the crystal packings and thus influenced the phase-transition points and types. The variable-temperature X-ray diffraction data for crystal 1 revealed the occurrence of a phase transition in the high-temperature phase with the space group of P21/c and in the low-temperature phase with the space group of P21/n. Crystal 2 exhibited the same space group P21/c at different temperatures. The results indicated that crystals 1 and 2 both underwent an iso-structural phase transition.

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Disorder in crystals of dioxofluorotungstates, (NH4)2WO2F4 and Rb2WO2F4

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768108033053 ◽

2008 ◽

Vol 64 (6) ◽

pp. 645-651 ◽

Cited By ~ 23

Author(s):

Anatoly A. Udovenko ◽

Natalia M. Laptash

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Symmetry Axis ◽

Crystal Form ◽

X Ray Diffraction ◽

Twin Structure ◽

Static Disorder ◽

X Ray ◽

Independent States ◽

Lower Temperature

Dioxotetrafluorotungstates (NH4)2WO2F4 [(I) at 297 K and (II) at 133 K] and Rb2WO2F4 (III) were synthesized in a single-crystal form and their structures were determined by X-ray diffraction. Two independent states of the cis-WO2F4 octahedron are characteristic of static and dynamic disorder in structure (I). Dynamically disordered W2 is displaced from the symmetry axis producing four possible orientations of anion that permits O and F atoms to be identified in separate orientations owing to the inherent differences between W—O and W—F bonding. After the phase transition at lower temperature (201 K), (I) transforms into the twin structure (II) with complete O/F ordering. Structure (III) is characterized by full O/F static disorder without any phase transitions at lower temperature.

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