Physico-Chemical nanomaterials science

Violet and red photoluminescence of RE-TM-B microneedles 
Koplak O.V., Dvoretskaya E.V. 
Institute of Problems of Chemical Physics, Semenov av. 1, Chernogolovka, Russia 142432 
E-mail: o.koplak@gmail.com

Ferromagnetic microwires, microcables, microneedles attract an attention of specialists due to new fundamental phenomena and wide practical application, both. Magnetic micromagnets can be applied in biology and medicine as magnetic tweezers and sensors of low magnetic field, temperature and stresses. We present growth, structure and analysis of magnetic and luminescence properties of new class of RE-TM microneedles. The (PrDy)(FeCo)B microneedles were grown by pendant melt drop technique. These micro needles contain amorphous phase as well as inclusions 2-14-1 and 2-1 magnetic phases and Pr, Dy oxides. We present mapping of chemical composition and the mapping of ultraviolet (UV) stimulated luminescence on RE-TM-B microwire. Intensive UV stimulated blue and red photoluminescence of the Dy2O3 and Pr2O3 inclusions was observed in “as grown” and in the acid polished microneedles.

Figure 1. SEM image of the (PrDy)(FeCo)B microneedles.

In agreement with the EDX spectrum oxides of the rare-earth elements incorporated in the microneedles as inclusions of 5-10 μm sizes are presented in the bulk as well as on the surface of the microneedles. The emission spectra of Dy3+ ions under 350 nm excitation corresponds to visible emission band located at ~ 480 nm corresponding to 4F9/2→6 H15/2 transition. The emission peak results in cool violet sources corresponding to the localized oxide inclusions in our experiments. Red photoluminescence corresponds to the well-known peak centered at ~ 610 nm assigned to the transition in Pr3+ ions from the 1D2 to the 3H4 state. Oxide inclusions can be used for the local probing of the oxidization state, which is very important to determine magnetic quality of materials.
This work was supported by the Russian Foundation for Basic Research 20-32-70025 “Stability”.