Atomic underlayer formation during the reaction of Ti{0001} with nitrogen

Shih, H. D.; Jona, F.; Jepsen, D. W.; Marcus, P. M.

doi:10.1016/0039-6028(76)90328-9

Cited by 98 publications

(17 citation statements)

References 15 publications

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“…ZrO rather than to that of the final oxidation product, ZrO,, which forms at higher oxygen exposures or higher temperatures ( 1,13). In one specific ideal model for these surfaces, the 0 atoms occupy sites just between the first and second metal layers (analogous to the N underlayer reported at the Ti (0001) surface (14)), but alternative ideal models have 0 atoms occupying octahedral sites between various numbers of metal layers (5,15). For any of these models, increasing 0 content beyond the occupation of 114 of the interlayer sites must inevitably increase disorder, with consequent decrease in halforder beam intensity and increase in beam width.…”

Section: Onset Of Depletionmentioning

confidence: 99%

Studies on surfaces of Zr(0001) that contain oxygen and show (2 × 2)-type low-energy electron diffraction patterns

Wong¹,

Mitchell²

1987

Can. J. Phys.

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Oxygen chemisorption on the Zr(0001) surface has bccn studied in the low-cxposure regime with Auger electron spectroscopy and measurements of the width of a half-order low-cncrgy clcctron diffraction (LEED) beam. The new observations and conclusions are as follows. (i) The diffusion of 0 atoms to the bulk cffcctivcly starts at around 236°C. (ii) Oxygen adsorbs in a disordered state at room temperature and orders sufficiently to show a (2 x 2)-type LEED pattern on heating to 220°C. (iii) With increasing 0 exposure, 114, 112, and 314 of the available adsorption sites can bc systematically filled, while showing the apparent (2 X 2)-LEED pattern, prior to the cstablishmcnt of an ordered ( 1 x 1)-0 surface. (iv) The process in (iii) can be reversed by starting with the ( 1 x 1)-0 surface and heating above 236°C.La chimisorption de I'oxygkne sur la surface Zr(0001) a CtC CtudiCe, dans Ic rCgimc de faible exposition, cn utilisant la spcctroscopie des Clcctrons Auger et dcs mcsures de la largeur d'un hisceau LEED dc demi-ordre. Les nouvellcs obscrvations et conclusions sont les suivantcs: (i) la diffusion volumiquc des atorncs 0 commence effcctivement a environ 236°C; (ii) I'oxygknc cst adsorb6 dans un Ctat dksordonnC tempCraturc ambiante et s'ordonne suffisamment pour prCsenter un profil LEED de type (2 X 2) aprks chauffage i 220°C: (hi) en augrncntant I'cxposition a 0 on pcut remplir systCmatiquement 114, 112 ct 314 dcs positions d'adsorption disponibles, cn gardant Ic profil LEED apparent (2 X 2). avant I'Ctablissement d'une surfacc ordonnee (1 x 1)-0; (iv) lc processus (iii) pcut etrc inverse cn partant avec la surface (1 x 1)-0 ct en chauffant au-dessus de 236°C.[Traduit par la revue]Can. J. Phys. 65. 461 (1987)

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Section: Onset Of Depletionmentioning

confidence: 99%

Studies on surfaces of Zr(0001) that contain oxygen and show (2 × 2)-type low-energy electron diffraction patterns

Wong¹,

Mitchell²

1987

Can. J. Phys.

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“…There are, however, exceptions. In the group IV transition metal-light element surface systems such as Ti͑0001͒-͑1ϫ1͒-N, 1 Ti͑0001͒-͑2ϫ2͒-O, [2][3][4] Zr͑0001͒-͑2ϫ2͒-O, [5][6][7] Zr͑0001͒-͑2ϫ1͒-O, 8,9 Zr͑0001͒-͑1ϫ1͒-O, 10 Zr͑0001͒-͑1ϫ1͒-N, 11 Zr͑0001͒-͑1ϫ1͒-C, 12 and Zr͑1010͒-͑2ϫ4͒-O, 13 the favorable adsorption sites have been reported to be subsurface, based on low energy electron diffraction ͑LEED͒, Auger, and work-function measurements. The unusual adsorption energetics make these systems particularly worth studying from a theoretical point of view.…”

Section: Introductionmentioning

confidence: 99%

First-principles calculation of oxygen adsorption on Zr(0001) surface: Possible site occupation between the second and the third layer

Yamamoto

Chan

et al. 1996

Phys. Rev. B

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The oxygen adsorption on the Zr͑0001͒ surface is studied using first-principles total-energy and force calculations. We calculated the atomic structure, heat of adsorption, work function, and electronic structure for oxygen occupying various surface and subsurface sites for both the Zr͑0001͒-͑1ϫ1͒-O and Zr͑0001͒-͑2ϫ1͒-O system. We found that the energetically most favorable occupation sites for oxygen are the octahedral sites between the second and the third layer. The change in the work function induced by oxygen adsorption depends strongly on the position of the adsorbed oxygen atoms and the calculated change of work function at the energetically most favorable site is consistent with previous experiments. A large difference in the electronic structure between the overlayer and subsurface adsorption is also found. ͓S0163-1829͑96͒06743-4͔

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“…We have accordingly been undertaking a project adsorbing gas, the relative amounts of adsorbed species were assessed to investigate the structural chemistry of the (000 1 ) surface of with appropriate Auger peak height ratios; specifically Rc, Ro, and Rp zirconium with low-energy electron diffraction (LEED) (1-3), motivated both by some interesting early observations for the Rc = A27o/A92, RO = A s I o / A~~~ RP = A I ? o / A~~ corresponding sukace of titaniumV (4,5) and by the general technological importance of the surface chemistry of zirconium (6,7). Our interest in the Zr(000 1) surface concentrates on the structures resulting from chemisorption, that is with coverages of the order of a monolayer formed by exposures to less than 10 Langmuir (1 L = lop6 Torr s) of reactive gas.…”

Section: Introductionmentioning

confidence: 99%

LEED and AES studies of chemisorption resulting from low exposures of C₂H₄, CO, and PH₃ to the (0001) surface of zirconium

Lou¹,

Wong²,

Mitchell³

1988

Can. J. Chem.

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. Can. J. Chem. 66, 3157 (1988). Low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES) have been used to study for the first time the chemisorption systems formed on the (000 1 ) surface of zirconium by exposing to C2H4, CO, and pH3 in the one to ten Langmuir regime. The adsorptions are done at room temperature, but there is subsequent heating to optimize the surface ordering. The main observations are as follows: ( i ) after heating C2H4-covered surfaces to effect hydrogen desorption, the remaining carbon can form two different ordered (1 X I)-C structures; (ii) CO forms both (2x2)-and (I X 1)-type structures; (iii) the temperature at which the bulk diffusion of oxygen becomes significant, as determined by AES, is about 40°C greater on a CO-treated surface than for an 02-treated Zr(000 1) surface; and (iv) heating a pH3-covered surface can yield a weakly-ordered (3 X3)-P structure. The observation (iv) contrasts with that for the analogous surface prepared previously with H2S; the poorly developed (3 X 3)-P surface structure results from the fact that the temperatures required for surface ordering overlap with those which yield a loss of phosphorus from the surface region.J. R. Lou, P. C. WONG et K. A. R. MITCHELL. Can. J. Chem. 66, 3157 (1988). Faisant appel 2 la diffraction Clectronique de faible Cnergie (LEED) et i la spectroscopie Clectronique de Auger (AES), on a CtudiC pour la premitre fois les systkmes de chemisorption formCs a la surface (000 1 ) du zirconium expose au C2H4, au CO et au pH3 dans l'un des dix rCgimes de Langmuir. On a realist les adsorptions a la temptrature ambiante avec un chauffage subsCquent pour optimiser l'ordonnance la surface. Les principales observations sont les suivantes : ( i ) apr2s le chauffage des surfaces couvertes de C2H4, pour affecter la dCsorption de l'hydrogtne, les atomes de carbone restants peuvent former deux diffkrentes structures ordonnCes de type (I x 1)-C; (ii) le CO forme deux structures de type (2 X2) et (1 X 1); (iii) la temperature i laquelle le gros de la diffusion de l'oxygkne devient significative, telle que determinee par AES, est plus Clevte d'environ 40°C pour une surface traitCe au CO que pour une surface de Zr(000 1 ) traitte a I'oxygkne et (iv) une surface couverte de pH2 peut donner une structure P de type (3x3) faiblement ordonnCe. L'observation (iv) contraste avec celle relative i la surface analogue prCparCe antkrieurement avec du H2S. La structure P de type (3 X 3) faiblement dCveloppCe rCsulte du fait que la temperature requise pour l'agencement de la surface rejoint celles qui conduisent 1 une perte de phosphore i partir de la surface.[Traduit par la revue]

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Atomic underlayer formation during the reaction of Ti{0001} with nitrogen

Cited by 98 publications

References 15 publications

Studies on surfaces of Zr(0001) that contain oxygen and show (2 × 2)-type low-energy electron diffraction patterns

Studies on surfaces of Zr(0001) that contain oxygen and show (2 × 2)-type low-energy electron diffraction patterns

First-principles calculation of oxygen adsorption on Zr(0001) surface: Possible site occupation between the second and the third layer

LEED and AES studies of chemisorption resulting from low exposures of C₂H₄, CO, and PH₃ to the (0001) surface of zirconium

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Atomic underlayer formation during the reaction of Ti{0001} with nitrogen

Cited by 98 publications

References 15 publications

Studies on surfaces of Zr(0001) that contain oxygen and show (2 × 2)-type low-energy electron diffraction patterns

Studies on surfaces of Zr(0001) that contain oxygen and show (2 × 2)-type low-energy electron diffraction patterns

First-principles calculation of oxygen adsorption on Zr(0001) surface: Possible site occupation between the second and the third layer

LEED and AES studies of chemisorption resulting from low exposures of C2H4, CO, and PH3 to the (0001) surface of zirconium

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LEED and AES studies of chemisorption resulting from low exposures of C₂H₄, CO, and PH₃ to the (0001) surface of zirconium