<i>Anodic Oxide Films</i>

Young, L.; Liebhafsky, H. A.

doi:10.1063/1.3058227

Cited by 270 publications

(88 citation statements)

References 51 publications

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“…[14][15][16][17][18][19][20] Early studies suggested that the initial oxidation stages leading to passivity could be defined as a dissolution-precipitation mechanism of either Sn(OH) 2 or SnO. 21,22 Shah and Davies 23 suggested two parallel processes, metal dissolution and oxide formation.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, in general, it is proposed that the result of the first passivation step is a thin layer of Sn(IV) hydroxide. In very alkaline solutions, Shams El Din and Abd El Wahab 25 concluded that the primary passivation of tin occurs when the metal is covered with a film of Sn(OH) 2 or SnO, and then permanent passivity occurs with a continuous layer of Sn(OH) 4 covering the surface, while Varsanyi et al, 14 using Mössbauer spectroscopy, found that the film formed at low potentials was duplex, consisting on highly amorphous Sn(OH) 2 28,29 More recently, it has been reported that tin behaves as a typical valve metal and that the growth of the film involves field-assisted migration of ions through the oxide. 20 The films were found to be nonstoichiometric, having an excess of tin atoms or oxygen vacancies that resulted in n-type conductivity.…”

Section: Introductionmentioning

confidence: 99%

“…These films are most frequently non-stoichiometric oxides and of amorphous or polycrystalline structure. 2 The principles of the band theory of solids have been quite successfully extended to this type of materials 3 and it is known that the presence of a semiconducting oxide film determines the charge distribution and the potential drop at the metal-metal oxide-electrolyte interface, i.e., the character of the double layer. Moreover, in the case of tin the understanding of the local structural and electronic properties of these thin solid films is important in the areas of microelectronics, optical film semiconductor technology and corrosion, since SnO 2 is one of the most studied metal oxides due to its wide applications ranging from electrochemistry to optics, solar cells or gas sensor.…”

Section: Introductionmentioning

confidence: 99%

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An electrochemical study of tin oxide thin film in borate buffer solutions

Dı́az¹,

Díez‐Pérez²,

Gorostiza³

et al. 2003

J. Braz. Chem. Soc.

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Neste trabalho, foi estudado o comportamento eletroquímico de estanho policristalino em soluções de tampão borato com pH 7.5, utilizando voltametria cíclica, eletroquímica com microscopia de varredura (EC-STM) e espectroscopia de impedância eletroquímica. Os potenciais do pico principal de redução do óxido e de geração de hidrogênio deslocaram-se de forma sistemática para valores mais negativos quando se aumentou o potencial anódico de formação do filme. Foi discutida a natureza dos diferentes óxidos formados e também foi dada nova atribuição aos processos de oxidação do estanho e de redução de seus óxidos.The electrochemical behavior of tin polycrystals in borate buffer solutions at pH 7.5 was systematically investigated using cyclic voltammetry, EC-STM and electrochemical impedance measurements. A systematic shift to more negative values of the potentials corresponding either to the major reduction peak either to the hydrogen evolution was measured when the anodization potential used for film growth was increased. A discussion about the different oxides there formed was included and a reassignation of tin oxidation and tin oxides reduction processes was given.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An electrochemical study of tin oxide thin film in borate buffer solutions

Dı́az¹,

Díez‐Pérez²,

Gorostiza³

et al. 2003

J. Braz. Chem. Soc.

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“…The passive films, constituted of amorphous niobium pentoxide 3 , can be easily thickened by anodic polarisation [3][4][5][6][7] ; the oxide growth occurs by high-field ion migration in the film 8,9 . Amorphous niobium pentoxide has a density 10 of 4.74 g cm -3 and a rather high concentration of oxygen vacancies (10 19 cm -3 ) that, injected at the metal/oxide interface, act as donor states and make the oxide an n-type semiconductor 11,12 ; Di Quarto et al 4 , studying films of various thickness (21 nm ≤ d ≤ 210 nm) formed in 0.5 mol/L H2SO4, determined their relative permittivity as being equal to 42.…”

Section: Introductionmentioning

confidence: 99%

“…Being a valve metal, niobium passivates with a high corrosion resistance in most common aqueous media [1][2][3][4] . The passive films, constituted of amorphous niobium pentoxide 3 , can be easily thickened by anodic polarisation [3][4][5][6][7] ; the oxide growth occurs by high-field ion migration in the film 8,9 .…”

Section: Introductionmentioning

confidence: 99%

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

Biaggio¹,

Bocchi²,

Rocha‐Filho³

et al. 1997

J. Braz. Chem. Soc.

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The electrical and semiconducting properties of thin anodic passive films potentiostatically formed (1 V ≤ E f ≤ 5 V vs. sce) on polycrystalline niobium electrodes in aqueous 0.5 mol/L H3PO4 solutions (pH 1.3) were studied, at room temperature, using electrochemical impedance spectroscopy. The data were analysed with a transfer function using a non-linear fitting routine, assuming that the resistance of the film is coupled in series with the faradaic impedance of the Nb(0) → Nb(V) reaction, and these in parallel with the capacitance of the passive film/electrolyte interface. The relative permittivity of the films was estimated as about 44. The number concentration of donors (ND) in the films was found to decrease with E f (i.e., with increasing film thickness). A flat band potential value of -0.72 V was also obtained from Mott-Schottky plots.Utilizando-se a espectroscopia de impedância eletroquímica, foram estudadas as propriedades elétricas e semicondutoras de filmes anódicos passivos formados potenciostaticamente (1 V ≤ E f ≤ 5 V vs. ecs) sobre eletrodos de nióbio policristalino em soluções aquosas de H3PO4 0,5 mol/L (pH 1,3), a temperatura ambiente. Os dados foram analisados com uma função de transferência usando uma rotina de ajuste não-linear, supondo que a resistência do filme está acoplada em série com a impedância faradaica da reação Nb(0) → Nb(V) e estas em paralelo com a capacitância da interface filme/eletrólito. A permissividade relativa dos filmes foi estimada como cerca de 44. Encontrou-se que a concentração em número de doadores (ND) nos filmes decresce com E f (isto é, à medida que a espessura do filme aumenta). A partir de gráficos de Mott-Schottky, também obteve-se um valor de -0,72 V para o potencial de banda plana.

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