Phonon Instability and Broken Long-Ranged p Bond in Ge-Sb-Te Phase-Change Materials from First Principles

2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Young-Sun Song ◽  
Jeongwoo Kim ◽  
Seung-Hoon Jhi
Keyword(s):  
Phase Change ◽  
First Principles ◽  
Phase Change Materials

scholarly journals Lattice Thermal Conductivity of mGeTe•nSb2Te3 Phase-Change Materials: A First-Principles Study

Crystals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 136 ◽  
Author(s):  
Yuanchun Pan ◽  
Zhen Li ◽  
Zhonglu Guo
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Data Storage ◽  
First Principles ◽  
Phase Change Materials ◽  
Lattice Thermal Conductivity ◽  
Transport Theory ◽  
Large Contribution ◽  
Thermal Transport Property ◽  
Boltzmann Transport Theory

As the most promising materials for phase-change data storage, the pseudobinary mGeTe•nSb2Te3 (GST) chalcogenides have been widely investigated. Nevertheless, an in-depth understanding of the thermal-transport property of GST is still lacking, which is important to achieve overall good performance of the memory devices. Herein, by using first-principles calculations and Boltzmann transport theory, we have systematically studied the lattice thermal conductivity along the out of plane direction of both stable hexagonal and meta-stable rock-salt-like phases of GST, and good agreement with available experiments has been observed. It is revealed that with the increase of the n/m ratio, the lattice thermal conductivity of hexagonal GST increases due to the large contribution from the weak Te-Te bonding, while an inverse trend is observed in meta-stable GST, which is due to the increased number of vacancies that results in the decrease of the lattice thermal conductivity. The size effect on thermal conductivity is also discussed. Our results provide useful information to manipulate the thermal property of GST phase-change materials.

Investigation on Ge5−x Sb x Te5 phase-change materials by first-principles method

2010 ◽  
Vol 99 (4) ◽  
pp. 961-964 ◽  
Author(s):  
Naihua Miao ◽  
Baisheng Sa ◽  
Jian Zhou ◽  
Lihua Xu ◽  
Zhimei Sun ◽  
...  
Keyword(s):  
Phase Change ◽  
First Principles ◽  
Phase Change Materials ◽  
First Principles Method

scholarly journals Unusual Force Constants Guided Distortion-Triggered Loss of Long-Range Order in Phase Change Materials

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3514
Author(s):  
Jiong Wang ◽  
Dongyu Cui ◽  
Yi Kong ◽  
Luming Shen
Keyword(s):  
Phase Change ◽  
Long Range ◽  
First Principles ◽  
Phase Change Materials ◽  
Nearest Neighbor ◽  
Range Order ◽  
Force Constants ◽  
Long Range Order ◽  
Dynamic Simulations ◽  
Functional Components

Unusual force constants originating from the local charge distribution in crystalline GeTe and Sb2Te3 are observed by using the first-principles calculations. The calculated stretching force constants of the second nearest-neighbor Sb-Te and Ge-Te bonds are 0.372 and −0.085 eV/Å2, respectively, which are much lower than 1.933 eV/Å2 of the first nearest-neighbor bonds although their lengths are only 0.17 Å and 0.33 Å longer as compared to the corresponding first nearest-neighbor bonds. Moreover, the bending force constants of the first and second nearest-neighbor Ge-Ge and Sb-Sb bonds exhibit large negative values. Our first-principles molecular dynamic simulations also reveal the possible amorphization of Sb2Te3 through local distortions of the bonds with weak and strong force constants, while the crystalline structure remains by the X-ray diffraction simulation. By identifying the low or negative force constants, these weak atomic interactions are found to be responsible for triggering the collapse of the long-range order. This finding can be utilized to guide the design of functional components and devices based on phase change materials with lower energy consumption.

First-principles study of magnetic interactions in3dtransition metal-doped phase-change materials

2014 ◽  
Vol 90 (14) ◽  
Author(s):  
T. Fukushima ◽  
H. Katayama-Yoshida ◽  
K. Sato ◽  
H. Fujii ◽  
E. Rabel ◽  
...  
Keyword(s):  
Phase Change ◽  
First Principles ◽  
Phase Change Materials ◽  
Magnetic Interactions ◽  
First Principles Study ◽  
Metal Doped

Automated first-principles mapping for phase-change materials

2017 ◽  
Vol 38 (9) ◽  
pp. 620-628 ◽  
Author(s):  
Marc Esser ◽  
Stefan Maintz ◽  
Richard Dronskowski
Keyword(s):  
Phase Change ◽  
First Principles ◽  
Phase Change Materials

Crystallization fractionation technology for paraffin-based phase change materials production

2020 ◽  
pp. 33-38
Author(s):  
S.S. Kruglov (Jr.) ◽  
◽  
G.L. Patashnikov ◽  
S.S. Kruglov (Sr.) ◽  
◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Materials
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