Effect of Oxygen Implantation on the Electrochemical Properties of Palladium
- PDF / 517,103 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 35 Downloads / 248 Views
solution can help to know the hydrogen absorption and migration processes. Palladium is well known as a typical material performing the hydrogen absorption and catalysis of hydrogenation reaction, and its electrochemical reaction is well established [3-5]. Therefore, the investigation of electrochemical properties of ion-implanted palladium is interesting not only as a basic process but also from the application point of view. In this article, the effect of Of-implantation on the electrochemical properties of Pd in a 0.25 mol dm- 3 1-1 2SO solution is investigated by cyclic voltammetry. The composition and structure of Oimplanted layers are analyzed by secondary ion mass spectrometry (SIMS), elastic recoil detection (ERD) combined with Rutherford backscattering spectrometry (RBS) and X-ray diffraction (XRD). The electrochemical reaction process of 0O-implanted Pd is discussed in relation to the surface composition and structure. 2. EXPERIMENTAL PROCEDURE The substrate used was polycrystalline sheet of 1 mm thick palladium with a purity of 99.9%, whose surface was mechanically Polished to a mirror finish. Implantation of 160+ was performed with doses of 1X10 17 , 3x10 17 and lxl0l ions cm-2 at an energy of 150 keV, and under a pressure of about2 104 Pa. To suppress heating by the ion bombardment, the beam current density was limited to 2 pA cn- . The electrochemical properties of unimplanted and O÷-implanted Pd were measured by multisweep cyclic voltammetry with a conventional three-electrode cell system [6]. The electrolyte was 0.25 mol dm-3 H1S04 solution, kept at 25±0.1 'C. Before the measurement, the solution was deaerated by bubbling wifh oxygen-free nitrogen gas for about 30 min. The initial potential sweep direction was negative from ±0 V vs. a saturated calomel reference electrode (SCE) at a sweep rate of 50 mV s-'. The lower and upper limits of potential sweeps were -0.4 and +0.8 V (vs. SCE) respectively. Charge ob287 0 Mat. Res. Soc. Symp. Proc. Vol. 354 1995 Materials Research Society
tained by integration of the current flowed during the voltammetric measurements was also recorded. The composition depth profile of O*-implanted layers was analyzed by secondary ion mass spec-
(RBS) trometry (SIMS). Elastic recoil detection (ERD) and Rutherford backscattering spectrometry were used to quantitatively measure the surface composition. In SIMS, a 5.5 keV 13 Cs÷ was used as a 145 primary beam 4and secondary ions detected were 239PdCs+, 149OCs+, CCs+ and 1H+. In ERD and RBS, a 2.275 MeV He** beam was impinged at an incident angle of 750 to the surface normal with a total fluence of 50 giC. The recoil 1H particles were detected through 8.3 jim Al film at 300 and the backscattered 4He particles were detected at 1600 to the incident beam trajectory. For calibration of H content, H*-implanted Si was used as a reference. To obtain information on the structure of O+-implanted layers, X-ray diffraction (XRD) measurements using a Seemann-Bohlin configuration diffractometer were taken. XRD patterns were obtained by 40 k
Data Loading...
