Simultaneously Control the Optical and Paramagnetic Properties of Bifunctional Na(Y0.8-xDyxYb0.18Er0.02)F4 Nanoparticles

Bifunctional Na(Y
_0.8-x
Dy
_x
Yb
_0.18
Er
_0.02
)F
₄
(x = 0,5%, 10%, 15%, 20%, 25%, 30%) nanoparticles (NPs) are synthesized by the solvothermal method. Green and red upconversion emissions and the paramagnetic property simultaneously highly depend on Dy
³⁺
content in Na(Y
_0.8-x
Dy
_x
Yb
_0.18
Er
_0.02
)F
₄
(x = 0, 5%, 10%, 15%, 20%, 25%, 30%). The tuning of upconversion emission intensity is resulted from the competition of the resonance energy transfer between Dy
³⁺
and Er
³⁺
, transition possibility of Yb
³⁺
→ Er
³⁺
, and concentration quenching, which is depended on the doping level of Dy
³⁺
. It is found that the magnetization of Na(Y
_0.8-x
Dy
_x
Yb
_0.18
Er
_0.02
)F
₄
NPs nonmonotonously depends on the concentration of Dy
³⁺
ions, which indicates that there may be the occurrence of the magnetic coupling of Dy
³⁺
ions and antiferromagnetic coupling of Dy
³⁺
, Y
³⁺
, Yb
³⁺
, and Er
³⁺
ions. The optimal content of Dy
³⁺
ions for simultaneous control of photoluminescence emission and paramagnetic properties is 15%. These conclusions are important for tuning optical properties and magnetization in bifunctional NPs simultaneously.