Surface Segregation of CoPt Polycrystalline Alloy

P.J. Godowski, T. Ohgi, D. Fujita
2003 Acta Physica Polonica. A  
a I nst i t ut e of E xp eri m ental P hysi cs, Uni versi ty of W ro c¤aw pl . Ma xa Bo rna 9, 50-204 Wro c¤aw, Po lan d b Na nom ateri al s La bo rato ry , Nati onal Insti tute for Ma teri al s Science 1-2-1 Sengen, Tsu kuba , Iba ra ki 305-0047, Japan Com posi tio n-dept h pro Ùlin g using di˜erent emission angles of X -ra y photo electron spectroscopy show ed surf ace enhancement of platinum concentration of the C oPt ( 30at % ) alloy extensi vely annealed to 1000 K in ultrahigh vacuum . T
more » ... rahigh vacuum . T he results are compared with theoretical predictio ns basing on mo dels w ith no crystal face dependence . PAC S numb ers: 68.35.Dv , 68.47.De, 79. 60.{i I n t r o d u ct io n Segregati on and chem i cal orderi ng on the al l oy surf a ces were extensi vel y i nvesti g ated i n the pa st and com prehensi ve revi ews ha ve app eared [1{ 3]. The kno wledge of the surf ace com positi on and structure of the al l oy cata l yst al l ows the predi cti on of the g iven chemi cal rea cti on b ehavi or (enha ncement or suppression due to the presence of a speciÙc i nterca l ati on) and i s of special i m p orta nce. Co bal t ba sed al loys pl ay a signi Ùcant ro l e i n industri al catal ysi s and thi s sti mul ates i nvesti g ati ons of these materi al s. The mag neti c pro perti es of CoPt al l oys, especia ll y thi n Ùlm s, whi ch a re im p orta nt i n the el ectro ni cs were i nvesti gated recentl y as well [4, 5] . The pha se di agra m of the Co{ Pt system shows tha t the al l oy crysta l l i zes to form a conti nuo us series of sol i d sol uti ons. In the regi on of 50 at % and 75 at% of Pt the di sorder{ order tra nsform ati ons exist gi vi ng ordered f cc superl atti ce trea ted as interm etal l ic system [6] . Ê corr esp on din g au t h o r; e-m ail : pj g@if d. u ni .wr o c.p l (3 5)
doi:10.12693/aphyspola.104.35 fatcat:ui2ufiqasbf4xb5i2u7jjtc6ay