[19a-A202-1~12] 10.5 Application of magnetic field

[19a-A202-9] Synthesis of Sr₂MgSi₂O₇ and non-contact optical manipulation of the particle levitating in a magnetic field

〇Yusuke Okano¹, Chiharu Tanebe¹, Masahisa Osawa¹, Noriyuki Hirota², Yasuhiro Ikezoe¹ (1.NIT, 2.NIMS)

Keywords:Magneto-Archimedes effect, Magnetic levitation, Persistent luminescent material

SrAl₂O₄ has been known well as a persistent luminescent material. Although the detail of the mechanism of its long persistent photoluminescence is still under investigation, the doped material, Eu, seems to change its oxidation state by the irradiation of UV light. For example, the magnetic moment of Eu ion decreased when it is oxidized from Eu²⁺ to Eu³⁺. Since the magnetic moment of Eu²⁺ is much larger than that of Eu³⁺, as a whole, the magnetic moment of the material decreases. Under the magnetic levitation condition, the equilibrium position of the levitating object depends on the magnetic susceptibility which is proportional to the magnetic moment of the object. Therefore, the fact that the magnetic moment can be controlled by light implies that we can move the levitating object without any physical contact. In this study, we tried non-contact manipulation of Sr₂MgSi₂O₇: Eu particle which was levitated in a paramagnetic aqueous solution in a magnetic field. The SrAl₂O₄ mentioned above is likely to be decomposed by humidity, therefore, in our study, we chose Sr₂MgSi₂O_7, whose relaxation time is not so long as that of SrAl₂O₄, but is very robust against the humidity. We synthesized the material, mixed the powder with Su-8, spread the mixture on a substrate by a spin coater, and, after UV irradiation by lithography equipment, made a small and hard piece of resin including Sr₂MgSi₂O₇: Eu powder.
The powder/resin complex was levitated in the superconducting magnet and then irradiated by UV light. The motion was recorded by a CCD camera and analyzed. The detail of the analysis will be discussed.