(p, ρ, T) measurements on trifluoromethane in the supercritical region at temperatures from 310 K to 350 K

Kamiya, M.; Muroki, K.; Uematsu, M.

doi:10.1006/jcht.1995.0032

Cited by 15 publications

(5 citation statements)

References 9 publications

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“…Effect of Pressure on Homogeneous Polymerization in scCHF 3 . One of features of supercritical fluids as a reaction medium is that their physicochemical properties such as the density and the dielectric constant (ε) can be manipulated by continuous changes of temperatures and/or pressures of the supercritical state. ,− Figure shows the effect of pressure on the conversion and the number-average molecular weight ( M n ) of PTFE in the homogeneous polymerization in scCHF 3 . Conversions and M n were low below the critical pressure ( P c = 4.8 MPa), where the medium exists as gaseous CHF 3 .…”

Section: Resultsmentioning

confidence: 99%

Polymerizations of Tetrafluoroethylene in Homogeneous Supercritical Fluoroform and in Detergent-Free Heterogeneous Emulsion of Supercritical Fluoroform/Water

2005

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Homogeneous polymerizations of tetrafluoroethylene (TFE) were executed in supercritical fluoroform (scCHF 3 ), and the resulting poly(tetrafluoroethylene) (PTFE) was uniformly dispersed and twined fibers (ca. 100 nm in width and 10 µm in length). The number-average molecular weight and the conversion of PTFE can be controlled by pressures of scCHF 3 from M n ) 10 4 to 10 6 and 60-80%, respectively. Heterogeneous detergentfree or stabilizer-free emulsion polymerization could be performed in the narrow condition of the scCHF 3 /water (5:3 in v/v) system at 17 MPa of the pressure with the 20-40% conversion, and the uniform spherical submicron particles (ca. 200 nm) of PTFE were obtained, in comparison with twined fibers from the homogeneous polymerization.

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Section: Resultsmentioning

confidence: 99%

Polymerizations of Tetrafluoroethylene in Homogeneous Supercritical Fluoroform and in Detergent-Free Heterogeneous Emulsion of Supercritical Fluoroform/Water

2005

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“…(1,2) The apparatus and experimental procedures are described in detail else-where. (6,7) However, the metal-bellows volumometer and the pressure vessel housing the bellows were reconstructed, because a very small hole was found in the volumometer in 1999 at the end of a work. (2) The bellows made of a stainless steel (AM350) were in use since 1992.…”

Section: Methodsmentioning

confidence: 99%

(p, ρ, T) measurements of (ammonia+ water) in the temperature range 310 K to 400 K at pressures up to 17 MPa. II. Measurements of{ xNH3+ (1 −x )H2O } at x=(1.0000, 0.8374, 0.6005, and 0.2973)

Kondo

Yasukawa

Uematsu

2002

The Journal of Chemical Thermodynamics

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“…Proposed simple models based on previously reported triple-layer RRAM mechanism [4]. Compare to typical bi-layer RRAM (a), the distribution oxygen vacancy can be abruptly changed in triple-layer RRAMs (b), (c).…”

Section: Figmentioning

confidence: 99%

“…2(b) and (c). The layer having high chemical potential can resolve the conducting filament faster than low chemical potential layer [4]. Based on this mechanism, maximized lightning-rod effects can be achieved by resolving the filament at only one layer.The proposed approaches are summarized in Fig.…”

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confidence: 99%

Conducting filament engineering by triple-layer RRAM for uniform resistive switching

Lee¹,

Park²,

Park³

et al. 2013

Extended Abstracts of the 2013 International Conference on Solid State Devices and Materials

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IntroductionRecently, in filament type random access memory (RRAM), variability of switching parameters is one of significant obstacles to commercialization. Thus, various approaches have been proposed to improve the variability of switching parameters. Especially, a lightning-rod effect which is a control of filament dissolution region was proposed as a simple and effective approach [1]. According to previous researches, switching uniformity of various parameters such as read resistance (R read ), set voltage (V set ), and reset current were significantly improved by decreasing reset bias (V reset ). It can be explained by narrower physical gap between an electrode and conducting filament by the decreased V reset . Since the switching non-uniformity comes from the random formation of conducting filament path in the physical gap, we can improve switching uniformity by minimizing the physical gap (lightning-rod effect). However, the resistance ratio (on/off ratio) which determines operation window is degraded due to the reduced physical gap, as shown in Fig. 1. This relation can be defined as a trade-off between the lightning-rod effect (narrower physical gap) and on/off ratio. Therefore, to improve uniformity with reasonable on/off ratio, we need to optimize both the lightning-rod effects and the resistance ratio.Based on the previous papers, inserting additional layer can improve on/off ratio [2]. Thus, we inserted additional layer into typical bi-layer structure RRAM. Moreover, TiO x layer which could lead to non-linear LRS was employed as an interlayer for non-linear resistive switching [3]. The mechanism of triple-layer RRAM was proposed by the difference of oxygen vacancy concentration and chemical potential, as shown in Fig. 2(b) and (c). The layer having high chemical potential can resolve the conducting filament faster than low chemical potential layer [4]. Based on this mechanism, maximized lightning-rod effects can be achieved by resolving the filament at only one layer.The proposed approaches are summarized in Fig. 2(a). To improve switching uniformity without on/off ratio degradation, electrical and structural optimizations such as a limited switching region (lightning-rod effect), bi-layer structure, and insertion of buffer layer were proposed.

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(p, ρ, T) measurements on trifluoromethane in the supercritical region at temperatures from 310 K to 350 K

Cited by 15 publications

References 9 publications

Polymerizations of Tetrafluoroethylene in Homogeneous Supercritical Fluoroform and in Detergent-Free Heterogeneous Emulsion of Supercritical Fluoroform/Water

Polymerizations of Tetrafluoroethylene in Homogeneous Supercritical Fluoroform and in Detergent-Free Heterogeneous Emulsion of Supercritical Fluoroform/Water

(p, ρ, T) measurements of (ammonia+ water) in the temperature range 310 K to 400 K at pressures up to 17 MPa. II. Measurements of{ xNH3+ (1 −x )H2O } at x=(1.0000, 0.8374, 0.6005, and 0.2973)

Conducting filament engineering by triple-layer RRAM for uniform resistive switching

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