The Impact of Cr3+ Doping on Temperature Sensitivity Modulation in Cr3+ Doped and Cr3+ Nd3+ Co-doped Y3Al5O12 Y3Al2Ga3O12 and Y3Ga5O12 Nanothermometers

摘要

A new approach to enhance the sensitivity of transition metal ion based nanocrystalline luminescent thermometer is presented. It was shown that the increase of Cr³⁺ concentration in three types of garnet host namely Y3Al5O12, Y3Ga5O12, and Y3Al2Ga3O12 allows for significant enhancement of their performance in non-contact thermometry. This phenomenon is related to the weakening of the crystal field strength due to enlargement of average Cr³⁺-O²⁻ distance at higher Cr³⁺ concentrations. By increasing Cr³⁺ concentration from 0.6 to 30%, the sensitivity increased by over one order of magnitude from S = 0.2%/°C to S = 2.2%/°C at 9°C in Y3Al2Ga3O12 nanocrystals. Moreover, it was found that due to the Cr³⁺ → Nd³⁺ energy transfer in the Cr³⁺, Nd³⁺ co-doped system, the usable Cr³⁺ concentration, for which its emission can be detected, is limited to 10% while the sensitivity at −50°C was doubled (from 1.3%/°C for Y3Al2Ga₃O₁₂:10%Cr³⁺ to 2.2%/°C Y₃Al₂Ga₃O₁₂:10%Cr³⁺, 1%Nd³⁺ nanocrystals).