Crystallization of the chalcogenide compound Sb<sub>8</sub>Te<sub>3</sub>

Kifune, Kouichi; Fujita, Takahisa; Kubota, Yoshiki; Yamada, Noboru; Matsunaga, Toshiyuki

doi:10.1107/s0108768111033738

Cited by 9 publications

(14 citation statements)

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“…This also demonstrates that they are crystallised to the own modulated structures provided by their compositions. The temperature dependence of γ for every specimen, which increases and settles in a specified value from a composition with heating, corresponds to the results of Sb 8 Te 3 and Sb 89 Te 11 . These results reveal that heat treatment and exact control of the composition is quite important, when considering the structure of Sb–Te system.…”

Section: Resultssupporting

confidence: 68%

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Crystal structures of X‐phase in the Sb–Te binary alloy system

Kifune

Fujita

Tachizawa

et al. 2013

Crystal Research and Technology

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It is well known that the Sb–Te binary system has a large number of incommensurately or commensurately modulated structures between Sb and Sb2Te3 compounds. These structures, which are long‐period trigonal stacking structures, possess their own modulation period γ, according to their composition in the thermal equilibrium. However, the structure of sputtered Sb–Te films with various compositions between the two compounds at both ends formed in a non‐thermal equilibrium showed smaller γ values, than those expected from their compositions without exception. A smaller γ value implies that its structure is closer to that of Sb with the shortest period in all Sb–Te modulated structures. With increase in temperature, all these transient structures with smaller γ, however, became stable, accompanying an increase of γ to acquire their original modulated structures.

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Section: Resultssupporting

confidence: 68%

“…The chemical formula is described as (Sb 2 ) n (Sb 2 Te 3 ) m , where n and m are integers. The number of blocks denoted by n and m changes according to the composition [10][11][12][13][14]. When the compound crystallises in a commensurately modulated structure, γ should be a rational number [15].…”

Section: Introductionmentioning

confidence: 99%

Crystal structures of X‐phase in the Sb–Te binary alloy system

Kifune

Fujita

Tachizawa

et al. 2013

Crystal Research and Technology

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“…Since it has limited solubility to Sb with relatively moderate slope of Sb-solvus, it is likely to decompose to δ+Sb 2 Te 3 phase mixture [28,29,[100][101][102][103], whereas Sb 2 Te 3 is equilibrium phase and may appear as diferent homologous forms [72,73,[104][105][106][107]. Precipitation of antimony-telluride second phase in δ-matrix is expected to afect TE performance due to contributions from both matrix and precipitate phases or variation of the average matrix composition.…”

Section: Formation Of Sb 2 Te 3 and Sb 8 Te 3 (R-3m) Phasesmentioning

confidence: 99%

“…Structural relaxation procedures are irst performed, allowing variation of cell volume and atom positions at all degrees of freedom, seting a convergence threshold of 10 [72,73]. Then, electronic band structure calculations are performed for both relaxed structures.…”

Section: The Base Agsbte 2 Phase-electronic Calculationsmentioning

confidence: 99%

Silver-Antimony-Telluride: From First-Principles Calculations to Thermoelectric Applications

Amouyal¹

2016

Thermoelectrics for Power Generation - A Look at Trends in the Technology

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Silver-antimony-telluride (AgSbTe 2 ) based compounds have emerged as a promising class of materials for thermoelectric (TE) power generation at the mid-temperature range. This Chapter demonstrates utilization of irst-principles calculations for predicting TE properties of AgSbTe 2 -based compounds and experimental validations. Predictive calculations of the efects of La-doping on vibrational and electronic properties of AgSbTe 2 compounds are performed applying the density functional theory (DFT), and temperature-dependent TE transport coeicients are evaluated applying the Bolzmann transport theory (BTE). Experimentally, model ternary (AgSbTe 2 ) and quaternary (3 at. % La-AgSbTe 2 ) compounds were synthesized, for which TE transport coeicients were measured, indicating that thermal conductivity decreases due to La-alloying. The later also reduces electrical conductivity and increases Seebeck coeicients. All trends correspond with those predicted from irst-principles. Thermal stability issues are essential for TE device operation at service conditions, e.g. changes of matrix composition and second-phase precipitation, and are also addressed in this study on both computational and experimental aspects. It is shown that La-alloying afects TE igure-of-merit positively, e.g., improving from 0.35 up to 0.50 at 260 °C. We highlight the universal aspects of this approach that can be applied for other TE compounds. This enables us screening their performance prior to synthesis in laboratory.Keywords: silver-antimony-telluride, irst-principles calculations, thermoelectric transport properties, Bolzmann transport theory, latice dynamics, thermal stability IntroductionIt is of utmost technological importance to develop predictive tools that will provide us with information about design of materials' functional properties. In this context, density functional theory (DFT) irst-principle calculations ofer us such possibilities [1][2][3][4] Despite of relatively high ZT values of AgSbTe 2 phase, it is still challenging to increase them to the range of 2-3. Reaching at this limit will enable us employing this material for energy conversion at power levels >500 W [34]. Reduction in latice thermal conductivity is a conventional way to enhance TE performance and is achieved by either doping with solute elements [35] or formation of second phases to stimulate phonon scatering [36][37][38]. These latice defects afect, of course, electronic properties, mainly electrical conductivity and Seebeck coeicient. Atempts to improve TE properties of AgSbTe 2 -based alloys by doping with diferent elements [19,25,[39][40][41][42][43][44][45][46][47] Notwithstanding the aforementioned successful experimental and computational atempts, a set of experimental routines, that is initiated and directed by predictions from irst principles for complete TE performance or any other computational procedure, is missing. Thermoelectrics for Power Generation -A Look at Trends in the Technology 148A signiicant step in this direction is introduced by o...

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“…Due to the smaller electronegativity of Cr (1.66) than those of Sb (2.05) and Te (2.1), the binding energy of CrSb and Cr-Te is smaller than that of Sb-Sb and Sb-Te, respectively. Previous studies show that the structure of Sb 4 Te consists of 15 layers stacked along c axis and the stacking sequence is Te-Sb-Te-Sb-Sb-Sb-Sb-Sb-SbSb-Sb-Sb-Sb-Te-Sb [11,20,21], so there are only part of Sb atoms bond with Sb and Te atoms. It is reasonable to conclude that Cr atoms replace partly these Sb atoms and bond with Sb and Te atoms, which further proves Cr is a substitutional impurity.…”

Section: Resultsmentioning

confidence: 99%

Investigation of Cr0.06(Sb4Te)0.94 alloy for high-speed and high-data-retention phase change random access memory applications

Song

Zhang

et al. 2015

Appl. Phys. A

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The effects of Cr doping on the structural and electrical properties of Cr x (Sb 4 Te) 1-x materials have been investigated in order to solve the contradiction between thermal stability and fast crystallization speed of Sb 4 Te alloys. Cr 0.06 (Sb 4 Te) 0.94 alloy is considered to be a potential candidate for phase change random access memory (PCM), as evidenced by a higher crystallization temperature (204°C), a better data retention ability (137.6°C for 10 years), a lower melting point (558°C), a lower energy consumption, and a faster switching speed in comparison with those of Ge 2 Sb 2 Te 5 . A reversible switching between set and reset states can be realized by an electric pulse as short as 5 ns for Cr 0.06 (Sb 4 Te) 0.94 -based PCM cell. In addition, Cr 0.06 (Sb 4 Te) 0.94 shows good endurance up to 1.1 9 10 4 cycles with a resistance ratio of about two orders of magnitude.

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Crystallization of the chalcogenide compound Sb₈Te₃

Cited by 9 publications

References 14 publications

Crystal structures of X‐phase in the Sb–Te binary alloy system

Crystal structures of X‐phase in the Sb–Te binary alloy system

Silver-Antimony-Telluride: From First-Principles Calculations to Thermoelectric Applications

Investigation of Cr0.06(Sb4Te)0.94 alloy for high-speed and high-data-retention phase change random access memory applications

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Crystallization of the chalcogenide compound Sb8Te3

Cited by 9 publications

References 14 publications

Crystal structures of X‐phase in the Sb–Te binary alloy system

Crystal structures of X‐phase in the Sb–Te binary alloy system

Silver-Antimony-Telluride: From First-Principles Calculations to Thermoelectric Applications

Investigation of Cr0.06(Sb4Te)0.94 alloy for high-speed and high-data-retention phase change random access memory applications

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Crystallization of the chalcogenide compound Sb₈Te₃