Kossel microdiffraction studies of TaO′

Harris, N.; Taylor, A.; Stringer, J.

doi:10.1016/0001-6160(73)90111-9

Cited by 6 publications

(4 citation statements)

References 9 publications

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“…Reliable evidence for the existence of independent TaO is absent and it is observed in bulky sample only in the presence of higher oxide [29]. Micro-diffraction studies proposed various tentative TaO structures [31][32][33][34]. We adopt Harris et al [33] model, as shown in fig.…”

Section: Resultsmentioning

confidence: 99%

“…Micro-diffraction studies proposed various tentative TaO structures [31][32][33][34]. We adopt Harris et al [33] model, as shown in fig. 1(a).…”

Section: Resultsmentioning

confidence: 99%

“…The above comparative results for titanium oxide system also demonstrate the importance of correlated multiple defects picture in understanding some phenomena in RS where numerous point defects are involved and interact with each other in a correlated manner. Given the significance of correlated atomic arrangement, the decrease of the relative stability of the oxygen vacancy over the metal interstitial in the sequence of 'single'>'multiple'>'correlated' and particularly the identical stability in the correlated multiple defects picture ('correlated') may be due to the real filament stoichiometry different than TaO and (or) the atomic ordering of the real filament in a more energetically stable structure other than the Harris one [33]. These differences can be subtle but significant enough to change the role of oxygen and metal induced defects in the RS process.…”

Section: Correlated Multiple Defectsmentioning

confidence: 99%

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Correlation and ordering of defects in the formation of conducting nanofilaments

Zhang¹,

Li²,

Shi³

2016

J. Phys. D: Appl. Phys.

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We study the dependence of the formation energies of oxygen and metal induced defects in Ta2O5, TaO2, TaO, TiO2 and Ti4O7 on the chemical potential of electron and atomic constitutes. In the study of single defect, metal induced defects are found to be preferable to oxygen induced defects. This is against the experimental fact of the dominant role of oxygen induced defects in the RS process. A simple multiple defects picture without correlated atomic rearrangement does not cure this problem. The problem is resolved under the correlated multiple defect picture where the multiple defects result in correlated atomic rearrangement and the final products show certain atomic ordering. IntroductionResistive switching (RS) in transition metal oxides (TMOs) has attracted great interests for a possible application in nonvolatile memory devices [1,2] and analog memristors [3][4][5]. Defect redistribution under the switching field is generally considered to play prominent role in the reversible RS [6][7][8]. In simple binary TMOs such as Ta2O5 and TiO2, the agglomeration (segregation) of oxygen vacancies and the subsequent growth (rupture) of the conducting filament is one of the most cited RS mechanisms [6][7][8]. These simple binary TMOs have the advantage of easy fabrication. However, the role of oxygen vacancies in the formation of conducting filaments at an atomic level is less well known. Besides the locally formed conducting path, the resistance can also be switched back and forth by the drift of the charged oxygen vacancies towards or away from one of the two electrodes which modifies the width of the interfacial depletion region and consequently the Schottky contact resistance [9]. Oxygen vacancy induced charge trap can also assist bulk like RS through continuous filling or emptying the traps, whose extent of charge occupation varies the resistance [10]. More complicated correlated TMOs like Pr0.7Ca0.3MnO3 [11], SmNiO3 [12] show metal-insulator transition which accounts for the RS. In these correlated TMOs, the oxygen vacancy coordination environment, which is subject to the driving field either electrically or thermally, modulates the local valence state of transition metal by rearranging the hybridization of transition metal d and oxygen p orbitals. Above mentioned TMOs show RS through effective change of the local oxidation state. Therefore, they are categorized as Redox (Reduction-oxidation) RS TMOs [5]. In this work, we focus on the filament type RS. High performance Ta2O5 based nonvolatile memory device [13] and TiO2 memristor based neuromorphic network [14] have recently been demonstrated. In situ characterization revealed that the conducting filaments in TiO2 and Ta2O5 are composed of Magneli phase Ti4O7 [15] and TaO1-x

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Section: Resultsmentioning

confidence: 99%

“…Micro-diffraction studies proposed various tentative TaO structures [31][32][33][34]. We adopt Harris et al [33] model, as shown in fig. 1(a).…”

Section: Resultsmentioning

confidence: 99%

Section: Correlated Multiple Defectsmentioning

confidence: 99%

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Correlation and ordering of defects in the formation of conducting nanofilaments

Zhang¹,

Li²,

Shi³

2016

J. Phys. D: Appl. Phys.

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“…The qualification is that 0 atoms which are released from oxide precipitates will in part escape to the surface, thence to be desorbed, and in part return to the precipitate. In the absence of preferential motion, as from strain fields, the fraction which escapes should be44 fraction escaping = (x>/(r -t (x)), (9) where r is the precipitate radius and (x) is the average distance of separation of a released 0 atom from a precipitate. Equation (9) would not present a particularly severe restriction since it would apply at the early stages of precipitation when r was small.…”

Section: Oxygen or Nitrogen Lossmentioning

confidence: 99%

On the nature of the phases formed when metals are implanted with oxygen or nitrogen

Kelly

1982

Radiation Effects

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Although the average composition change resulting from 0 or N implantation in a metal is small up to a dose of about 3 x 1016 ions/cmZ, the implanted atoms tend to be atomically mobile under the conditions used for bombardments and precipitation of an oxide or nitride can be expected. The object of this work is to explain what phases are formed. One model is based on the postulate that the precipitates are at the surface and have a high anion-to-cation ratio. The resultant phase therefore tends to be that which arises from the impact of any heavy particle on the surface of a high oxide or nitride. An alternative model is based on the postulate that the precipitates tend, independently of where they form, to be in qualified thermodynamic equilibrium with the metal. A consideration of the known examples of 0 or N implantation suggests that qualified thermodynamic equilibrium is the better guide to which phases are formed.

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Va — Metalle

Hörz¹,

Fromm²

1976

Reine Und Angewandte Metallkunde in Einzeldarstellungen

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Kossel microdiffraction studies of TaO′

Cited by 6 publications

References 9 publications

Correlation and ordering of defects in the formation of conducting nanofilaments

Correlation and ordering of defects in the formation of conducting nanofilaments

On the nature of the phases formed when metals are implanted with oxygen or nitrogen

Va — Metalle

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