Tuning the phase, morphology and size of monodisperse ScF3 and NaScF4 crystals through lanthanide doping

Abstract

Monodisperse ScF₃ and NaScF₄ nano-/micro-crystals were prepared by a simple solvothermal method. There were many important factors including the molar ratio of Na/F/(Sc + Ln) and Ln³⁺ doping to control the synthesis of the products. A phase transformation from monoclinic ScF₃ to hexagonal NaScF₄ was observed with different molar ratios of Na/F/Sc. Herein, the products doped with 1% Ln³⁺ (La–Lu, except Pm) demonstrated abundant phases, morphologies and sizes. Moreover, the products with different Lu³⁺ doping concentrations from 1% to 60% were prepared. The results revealed that different kinds of 1% Ln³⁺ (La–Lu, except Pm) and diverse concentrations of Lu³⁺ can modify the phase, morphology and size of the prepared products. A possible formation mechanism for the products with diverse morphologies is proposed. In addition, Ln³⁺-doped ScF₃ or NaScF₄ nano-/micro-crystals presented characteristic up/down-conversion fluorescence spectra.