Upconversion NaYF4:Yb:Er nanoparticles co-doped with Gd3+ and Nd3+ for thermometry on the nanoscale

Abstract

In the present work, the upconversion luminescence properties of oleic acid capped NaYF₄:Gd³⁺:Yb³⁺:Er³⁺ upconversion nanoparticles (UCNP) with pure β crystal phase and Nd³⁺ ions as an additional sensitizer were studied in the temperature range of 288 K < T < 328 K. The results of this study showed that the complex interplay of different mechanisms and effects, causing the special temperature behavior of the UCNP can be developed into thermometry on the nanoscale, e.g. to be applied in biological systems on a cellular level. The performance was improved by the use of Nd³⁺ as an additional dopant utilizing the cascade sensitization mechanism in tri-doped UCNP.