Electrochemical characterization of thin passive films on Nb electrodes in H3PO4 solutions

Biaggio, Sonia R.; Bocchi, Nerilso; Rocha‐Filho, Romeu C.; Varela, F.E.

doi:10.1590/s0103-50531997000600008

Cited by 20 publications

(15 citation statements)

References 23 publications

(44 reference statements)

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“…The resistance values of Nb 2 O 5 memristors in their initial state were in the range of 10 4 Ω, indicating modest semiconducting properties, as already reported [ 39 ]. A reproducible switching between HRS (≈10 4 Ω) and LRS (≈10 2 Ω) was established via an electroforming process in a negative direction for devices anodized in PB (up to −3.5 V) and in a positive direction for devices formed in CB (up to 2.5 V).…”

Section: Resultssupporting

confidence: 75%

Impact of Electrolyte Incorporation in Anodized Niobium on Its Resistive Switching

et al. 2022

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The aim of this study was to develop memristors based on Nb2O5 grown by a simple and inexpensive electrochemical anodization process. It was confirmed that the electrolyte selection plays a crucial role in resistive switching due to electrolyte species incorporation in oxide, thus influencing the formation of conductive filaments. Anodic memristors grown in phosphate buffer showed improved electrical characteristics, while those formed in citrated buffer exhibited excellent memory capabilities. The chemical composition of oxides was successfully determined using HAXPES, while their phase composition and crystal structure with conductive filaments was assessed by TEM at the nanoscale. Overall, understanding the switching mechanism leads towards a wide range of possible applications for Nb memristors either as selector devices or nonvolatile memories.

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Section: Resultssupporting

confidence: 75%

Impact of Electrolyte Incorporation in Anodized Niobium on Its Resistive Switching

et al. 2022

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“…Therefore, the electrochemical responses shown in Fig. 2 can be related with the formation of Ta 2 O 5 and Nb 2 O 5 passive films, such as has been reported in the literature [24][25][26][27][28][29][30][31].…”

Section: Voltammetric Characterizationmentioning

confidence: 66%

EIS characterization of tantalum and niobium oxide films based on a modification of the point defect model

Cabrera-Sierra

Hallen

Vazquez‐Arenas

et al. 2010

Journal of Electroanalytical Chemistry

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“…5, which has been previously used for EIS analysis of Nb and Ta oxides films. 4,8,20 A constant The R elNb is the resistance of the solution, R bNb is the resistance of the Nb 2 O 5 film; the CPE is a constant phase element, whose impedance is defined as Z CPE = 1/͓͑ j͒ n C͔, the n compensates the nonhomogenity of the system and C is the capacitance associated with the M/F/S junction of the Nb 2 O 5 film j is the imaginary number, and the angular frequency.…”

Section: C704mentioning

confidence: 99%

Influence of Potentiostatic Aging on Nb and W Oxides Formed in 0.1 M HClO[sub 4]

Vázquez

González

2007

J. Electrochem. Soc.

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The evolution of the electrical properties of Nb 2 O 5 and WO 3 films, at different formation potentials ͑E f ͒, in 0.1 M HClO 4 , were followed by electrochemical impedance spectroscopy ͑EIS͒. During the growth of the oxide films, EIS spectra were acquired every hour, maintaining the potentiostatic pulse during 20 h. The Nb 2 O 5 and WO 3 impedance spectra show variations vs potentiostatic aging. However, the Mott-Schottky analysis showed that the density of donors ͑N D ͒ does not depend on the potentiostatic aging but depends on the E f , while, the flatband potential ͑E FB ͒ is almost constant with the potentiostatic aging and E f , for both oxides. The relationship between the invariability of the semiconductor properties ͑N D and E FB ͒ with the potentiostatic aging and the variation of the impedance spectra, in the case of the W, can be explained by the formation of an external layer of WO 3 ·͑H 2 O͒ x , which must be very thin; the detachment of this layer causes a very small difference in the thickness, not modifying the semiconductor properties ͑N D and E FB ͒, but greatly changing the electric properties of the film, since WO 3 ·͑H 2 O͒ x is more resistive. A similar hydration process may occur in the Nb 2 O 5 films to a lesser extent.The valve metals ͑i.e., Al, Nb, W, Ti, Ta, Zr, among others͒ form a passive film when oxidized, which protects the inner metal from corrosion in aggressive media. The electronic properties of the passive film greatly determine the kinetics of charge transfer, at the oxide-film/solution ͑F/S͒ interface, and therefore are key factors in the knowledge of the corrosion processes. The characterization of the oxide passive films has increasingly been performed by electrochemical impedance spectroscopy ͑EIS͒. 1 In this technique, the capacitance of the metal/oxide-film/solution ͑M/F/S͒ junction, is measured as a function of frequency and/or electrode potential ͑Mott-Schottky analysis, M-S͒. The oxide passive film characterization with EIS requires that the system be at steady state; in order to reach this condition, the potential must be applied for a certain time, ͑sta-bilization time, t ss ͒. In the literature, the stabilization time varies from 1 h to 24 h, 2,3 for the same oxide film, under similar conditions. It is generally agreed that a system has reached steady-state conditions when the current density during the potentiostatic growth of the film is nearly constant ͑i ss ͒. At steady state, the electric properties of the passive oxides are expected to have an invariant global behavior ͑with the potentiostatic aging͒, of all the processes involved in the dynamic growing dissolution of the oxide films, including those occurring on the outer layer ͑F/S interface͒, where the reprecipitation of the aqueous metal oxide, as well as the hydration of the film, occur. These last processes could not be detected by direct current measurements ͑i.e., i vs t plots͒. In contrast, the EIS, being an ac technique, allows the detection of various processes with different relaxation times; t...

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Electrochemical characterization of thin passive films on Nb electrodes in H3PO4 solutions

Cited by 20 publications

References 23 publications

Impact of Electrolyte Incorporation in Anodized Niobium on Its Resistive Switching

Impact of Electrolyte Incorporation in Anodized Niobium on Its Resistive Switching

EIS characterization of tantalum and niobium oxide films based on a modification of the point defect model

Influence of Potentiostatic Aging on Nb and W Oxides Formed in 0.1 M HClO[sub 4]

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