Report on the design and test of liquid sample holder for SAXS measurements under static magnetic field

Full text: Here, we aim to present the design and test of a sample holder for liquids to perform SAXS measurement under static magnetic field. This is a modification of the already existing holder available in SAXS2 beam line. The design was discussed at the last RAU2012, the construction is under progress nowadays and the implementation will be carried out under proposal D11A - SAXS1-13714 (Nov. 2012). This device can find applications in the study of induced anisotropy in colloidal magnetic dispersion and rheological problems, among others. The static magnetic field are produced with commercially available NdFeB magnets of remanent field Br=1.12 T. We have designed two distinct configurations to achieve homogenous field, parallel and perpendicular to the beam direction. Also, the arrangements can be modify to vary the field intensity up to 0.7 T. We choose to keep the original material of the liquid sample holder (stainless steel 316L) because austenitic stainless steels are non-magnetic in the annealed, fully austenitic condition. The magnetic permeability of this material in this condition is generally less than 1.02 at 5 kA/m. To test the effectiveness of the field achieved with the projected magnets arrangements we choose the use of stable colloidal suspensions, consisting of single-domain spherical magnetic nanoparticles (NP) displaying very low polydispersity and dispersed in liquids. The mean primary particle sizes are in the range from 2 to 7 nm and coated with ∼ 2 nm oleic acid shell. This ensemble exhibited a nice SAXS pattern, which is the result of primary particle pattern superimposed to the power law behavior originated at the NP self organization. (author)