“…YVO 4 :Yb 3+ ,Tm 3+ , 33 Bi 2 MoO 6 : Yb 3+ ,Er 3+ ,Tm 3+ , 34 and LuVO 4 :Nd 3+ ,Yb 3+ . 35 However, upconversion luminescence has a much lower efficiency compared to the emission intensity upon host excitation. The efficiency of different excitation mechanisms, namely (1) through crystal host and (2) through direct absorption of rare earth ions, for synthesized nanothermometers was studied using excitation spectroscopy (Fig.…”