TY - JOUR
T1 - Neutron reflectivity measurements of titanium-beryllium multilayers
AU - Munter, Alan E.
AU - Heuser, Brent J.
AU - Skulina, Kenneth M.
N1 - Funding Information:
The authors are very grateful to C. Alford, Department of Chemistry and Material Science, LLNL, for performing the depositions. The ANL work is supported by the US DOE, BES-Materials Sciences, under contract No. W-31-109-ENG-38. The XPS measurements were carried out at the Center for Microanalysis of Materials, University of Illinois, which is supported by the US DOE under grant DEFG02-91-ER45439. In addition, the help of R. Haasch at the University of Illinois with the XPS measurements is gratefully acknowledged.
PY - 1996/4/2
Y1 - 1996/4/2
N2 - Some of the best neutron supermirrors currently in production are made of alternating layers of nickel and titanium, with carbon added to the Ni to eliminate preferential growth. Reflectivities of 75-95% in the θc-2θc range are currently obtained from the Ni/C-Ti system. The Ti-Be multilayer system is presented here as a possible alternative to the Ni/C-Ti system. Titanium is one of the few elements which has a negative neutron scattering length, while beryllium has a relatively large positive scattering length. This makes for bilayer structures which have excellent neutron contrast, a necessary requirement of supermirror devices. Single-bilayer-spacing Ti-Be multilayers were prepared by magnetron sputtering onto 2mm thick silicon (001) substrates. Depositions were made with 10-80 bilayers at two different bilayer thicknesses of approximately 90 and 110 Å. Bulk layers of Ti and Be were also prepared to determine the scattering length density of each deposition component. The samples were measured at the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory on the POSYII reflectometer. First order Bragg peak reflectivities of up to 64% were observed. Data from the two bulk depositions and one multilayer deposition have been fitted using a genetic algorithm developed at IPNS. For the bulk depositions, the scattering length densities of Ti and Be depositions are -2.2 × 10-6 and 10.3 × 10-6 Å-2, respectively. In addition, results clearly indicate the presence of a 50 Å thick oxide layer on the bulk Ti deposition. The neutron scattering length density profile obtained from the neutron reflectivity measurements are in good agreement with XPS analysis of the oxide film which showed a mixture of TiO2 and Ti2O3.
AB - Some of the best neutron supermirrors currently in production are made of alternating layers of nickel and titanium, with carbon added to the Ni to eliminate preferential growth. Reflectivities of 75-95% in the θc-2θc range are currently obtained from the Ni/C-Ti system. The Ti-Be multilayer system is presented here as a possible alternative to the Ni/C-Ti system. Titanium is one of the few elements which has a negative neutron scattering length, while beryllium has a relatively large positive scattering length. This makes for bilayer structures which have excellent neutron contrast, a necessary requirement of supermirror devices. Single-bilayer-spacing Ti-Be multilayers were prepared by magnetron sputtering onto 2mm thick silicon (001) substrates. Depositions were made with 10-80 bilayers at two different bilayer thicknesses of approximately 90 and 110 Å. Bulk layers of Ti and Be were also prepared to determine the scattering length density of each deposition component. The samples were measured at the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory on the POSYII reflectometer. First order Bragg peak reflectivities of up to 64% were observed. Data from the two bulk depositions and one multilayer deposition have been fitted using a genetic algorithm developed at IPNS. For the bulk depositions, the scattering length densities of Ti and Be depositions are -2.2 × 10-6 and 10.3 × 10-6 Å-2, respectively. In addition, results clearly indicate the presence of a 50 Å thick oxide layer on the bulk Ti deposition. The neutron scattering length density profile obtained from the neutron reflectivity measurements are in good agreement with XPS analysis of the oxide film which showed a mixture of TiO2 and Ti2O3.
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U2 - 10.1016/0921-4526(95)00971-X
DO - 10.1016/0921-4526(95)00971-X
M3 - Article
AN - SCOPUS:0030562891
SN - 0921-4526
VL - 221
SP - 500
EP - 506
JO - Physica B: Condensed Matter
JF - Physica B: Condensed Matter
IS - 1-4
ER -