Iron-Ion Implantation Studied by Conversion-Electron Mössbauer Spectroscopy

Sawicka, R. D.; Sawicki, J.

doi:10.1007/978-3-662-08867-8_7

Cited by 18 publications

(8 citation statements)

References 73 publications

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“…As shown in Table 1, this peak position corresponds to Fe 3 + [21][22][23]. According to previously published CEMS measurements [1][2][3][4][5][6][7][8][9][10][11] all the Fe cations in the Fe depth profile of the oxidized sample are initially present in the trivalent state.…”

Section: I Surface Modificationmentioning

confidence: 73%

“…These results are of importance for the study of the structure [6] and electrochemical properties [7] of these implanted layers. Most information available on the charge state has been obtained with conversion electron Mrssbauer spectroscopy (CEMS) [8][9][10][11]. With CEMS the oxidation state of the implanted ions, in a shallow surface layer of about 100 nm thickness, is analyzed in a non-destructive way.…”

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confidence: 99%

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Oxidation state of Fe and Ti ions implanted in yttria-stabilized zirconia studied by XPS

Hassel

Burggraaf

1991

Appl. Phys. A

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Abstract. The oxidation state of Fe and Ti ions implanted in yttria stabilized zirconia (YSZ) was studied by XPS (X-ray photoelectron spectroscopy) in combination with depth profiling using Ar + sputtering. In the "as-implanted" state of the sample Fe was found to be present as Fe 3 +, Fe 2+ and as metallic Fe °. This is in agreement with earlier conversion electron Mrssbauer Spectroscopy measurements. For Ti-implanted YSZ in the "as-implanted" state the majority of the Ti is present as TP +, Ti 3+, and Ti 2+ ions, while a part of the Zr cations is present in the divalent oxidation state (Zr 2 +). After oxidation in air, the Fe and Ti ions are present only in the valence three and four oxidation states, respectively. PACS: 79.60.Eq, 61.70.Tm X-ray photoelectron spectroscopy (XPS) is frequently used to study the chemical nature of surfaces [1]. It gives information on the chemical composition as well as the oxidation state of the elements present in the surface. Ion beams can be used for surface cleaning or depth profiling. Hence in principle it is possible to study the oxidation state of elements in thin films as a function of the depth.During sputtering preferential removal of elements may occur. These effects originate from differences in the surface binding energies and from mass differences [2]. In oxides the lattice oxygen generally is sputtered preferentially with respect to the metal ions [2,3]. The remaining electrons of oxygen cause reduction of cations present in a thin surface layer, with a thickness comparable to the penetration depth of the bombarding ions [4]. It seems, however, not yet to be possible to correct sputtering depth profiles for these preferential sputtering effects.This study, which is part of a larger research effort [5], is intended to give information on the oxidation state of Fe and Ti ions in the "as-implanted" state of YSZ. These results are of importance for the study of the structure [6] and electrochemical properties [7] of these implanted layers. Most information available on the charge state has been obtained with conversion electron Mrssbauer spectroscopy (CEMS) [8][9][10][11]. With CEMS the oxidation state of the implanted ions, in a shallow surface layer of about 100 nm thickness, is analyzed in a non-destructive way. Few elements, however, have suitable isotopes for this technique. The charge state of 57Fe ions [11][12][13][14][15][16][17][18] can be studied very well, but the charge state of Ti cannot.In order to obtain results without any detailed description of the sputtering process at hand, a careful analysis of the evolution of the oxidation states of the cations as a function of the sputtering time is carried out with XPS. The data obtained from the samples in the "as-implanted" state are compared with the data, obtained under similar conditions, from samples with all cations in the highest oxidation state ("oxidized state"). From this analysis conclusions are drawn on the oxidation state of Fe and Ti ions in the "as-implanted" state of the YSZ sample.A disadvant...

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Section: I Surface Modificationmentioning

confidence: 73%

mentioning

confidence: 99%

Oxidation state of Fe and Ti ions implanted in yttria-stabilized zirconia studied by XPS

Hassel

Burggraaf

1991

Appl. Phys. A

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“…Earlier studies on implantation of the M6ssbauer active 57Fe isotope in YSZ, using conversion electron M6ssbauer spectroscopy (CEMS) [ 4,10 ], have shown that, in the "as-implanted" state, iron is present in the Fe °, Fe 2+ and Fe 3+ valence state. Annealing at 400°C (½ h) results in rapid oxidation of all Fe to Fe 3+.…”

Section: Characterization and Thermal Stability Of The Implanted Layermentioning

confidence: 99%

Oxygen transfer properties of ion-implanted yttria-stabilized zirconia

1992

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The influence of surface modification by ion implantation on oxygen transfer in yttria-stabilized zirconia (YSZ) has been studied. Implantation of 15 keV 56Fe in YSZ with a maximum dose of 8 X 10 ~6 atoms cm 2 yields reproducible surface layers of approximately 20 nm deep with a maximum Fe cation fraction of 0.5 at the surface. After annealing these layers are stable up to 700-800°C. The exchange current densities for the Fe-implanted layers, measured using porous gold electrodes, are a factor of 10-50 larger than observed for not-implanted YSZ. tsO isotope exchange experiments show that for Fc-implanted samples the surface oxygen exchange rate is at least a factor 30 larger than for normal YSZ. The electrode kinetics has been studied for normal and implanted YSZ using current-overvoltage measurements and impedance measurements under bias. An electrode reaction model for the transfer of oxygen has been developed. This model is able to explain the low frequency inductive loop in the impedance diagram which is observed at high cathodic and anodic polarizations for implanted as well as normal YSZ.

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“…The ions whose charge state has been studied are Fe, Au [42] and Sn [43]. This is mainly due to the fact that those ions are very suitable as a nuclide in Conversion Electron M6ssbauer spectroscopy (CEMS) experiments [18]. The charge state of, e.g., Fe has been studied in A1203 [19], MgO [20], ZrO2 [21], Mg2SiO4 [22], yttria stabilized zirconia [23], and garnets [24].…”

Section: As-implanted Statementioning

confidence: 99%

Structural, electrical and catalytic properties of ion-implanted oxides

Hassel

Burggraaf

1989

Appl. Phys. A

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Abstract. The potential application of ion implantation to modify the surfaces of ceramic materials is discussed. Changes in the chemical composition and microstructure result in important variations of the electrical and catalytic properties of oxides. 66.30, 81.40, 81.60, 61.70 Since the introduction of ion implantation as a surface modification technique, the electrical [1, 2], optical [3], magnetic [4], chemical [5], mechanical [6] and topographical [7] properties of solids have been modified. The potential use of ion implantation to modify the surfaces of ceramic materials has been discussed by Burggraaf et al. [56]. These changes in the macroscopic properties correspond to the changes in chemical composition and microstructure. In this paper this relationship is discussed for the electrical and catalytic properties of oxides, modified by ion implantation. PACS: Ion ImplantationIn the ion-implantation process, specific atoms are ionized, accelerated and mass selected [8]. Those high energetic ions (15 keV-2 MeV) penetrate in the solid and come to rest due to elastic and inelastic energy loss processes. A comprehensive treatment of the penetration of ions in solids has been given in [-9 and 10]. Depending on the process parameters the depth profile can be given different shapes, the penetration depth can be varied between some nanometers and about one micrometer and the dopant concentration in the surface can be raised to about 50 at.%. When the ion beam is properly scanned over the surface, lateral very uniform concentrations of the dopant are obtained. Due to the electrical control of the ion energy and dose, the technique is very reproducible.A major advantage of ion implantation is that a surface layer can be doped with any element, independent of its solubility in the substrate material. This means that one can produce metastable compounds, strongly supersaturated solid solutions and complex microstructures consisting of very finely dispersed precipitates with nanoscale dimensions in a matrix material. Several examples are discussed below. Microstructural Changes As-Implanted StateWhen an ion is implanted, it collides with the nuclei and electrons of the solid. In ionic oxides, only nuclear collisions result in defects [11]. Vacancies and interstitials are generated in both the anion and the cation sublattice. Interstitial loops nucleate and grow during irradiation. The lattice damage initially increases with the dose and finally saturates [11]. At that point as many defects are generated as annihilated by dynamic recovery processes in the solid. Dynamic recovery processes can be suppressed by cooling the target to low temperatures.The accumulation of defects in ion-implanted solids can result in a transition from a crystalline to an amorphous phase. This has been observed for, e.g., A1203 [12,13] [25]. The main conclusion from this model is that Fe 3 + can only exist in MgO as an isolated impurity. The fraction of Fe z + and Fe ~ is determined by the probability that, respectively, two Fe atoms and ...

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Iron-Ion Implantation Studied by Conversion-Electron Mössbauer Spectroscopy

Cited by 18 publications

References 73 publications

Oxidation state of Fe and Ti ions implanted in yttria-stabilized zirconia studied by XPS

Oxidation state of Fe and Ti ions implanted in yttria-stabilized zirconia studied by XPS

Oxygen transfer properties of ion-implanted yttria-stabilized zirconia

Structural, electrical and catalytic properties of ion-implanted oxides

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