Temperature dependent upconversion luminescence of Yb/Er codoped NaYF4 nanocrystals

Abstract

The upconversion luminescence of Yb/Er codoped NaYF4 nanocrystals was investigated at different temperatures from 295 to 10 K. The temperature dependent luminescence intensity of the nanocrystals showed very different behaviors as compared to their bulk powders. The intensity of the green emissions initially increased and then decreased as the measurement temperature was decreased. The experimental data were explained in terms of enhanced relaxation processes in the doped nanocrystals, which may need to be taken into account in many potential applications such as thermal sensing and biosensors.

Up-conversion luminescent properties and optical thermometry of LaMgAl11O19: Yb3+/Er3+ phosphors

“…1 shows the XRD pattern of LaMgAl 11 O 19 : 0.02Er 3 þ , 0.05Yb 3 þ phosphor obtained at calcinations temperature 1100 1C, which can be well-assigned to the reported data of LaMgAl 11 O 19 (JCPDS 26-0873) and confirm that the sample is of hexagonal structure with space group P6 3 /mmc [12]. [24][25][26]. Especially, the green emission is strong enough to be seen by naked eyes in LaMgAl 11 O 19 : 0.02Er 3 þ , 0.05Yb 3 þ sample as presented inset in Fig.…”

Sensing Using Rare-Earth-Doped Upconversion Nanoparticles

“…Yb/Er-codoped colloidal fluoride nanoparticles, therefore, become a promising nanothermometer for use in biology. The temperature dependence of Yb/Er codoped NaYF 4 powders were investigated independently by Suyver et al 110 and Wu et al 111, drawing the same conclusion as described in equation (5). Although Tm 3+ /Yb 3+ codoped Y 2 O 3 UCNPs were investigated as thermometers to detect a temperature range from 303 K to 753 K 112, the sensitivity of temperature (a fractional rate of change in the fluorescence intensity ratio with the temperature) is lower than Er 3+ /Yb 3+ -doped fluoride nanoparticles.…”

Comparative study on upconversion luminescence and temperature sensing of α- and β-NaYF4:Yb3+/Er3+ nano-/micro-crystals derived from a microwave-assisted hydrothermal route

“…Optical temperature sensing has been extensively investigated on the Er 3 þ -doped system due to the narrow energy gap between the 2 H 11/2 and 4 S 3/2 levels of Er 3 þ [11,12]. These two green emission levels are always in a thermal equilibrium at any temperatures due to the thermally coupled regime.…”

“…In addition, Er 3 þ has two neighbored levels of 2 H 11/2 and 4 S 3/2 whose populations meet the Boltzmann distribution law, thus the temperature of Er 3 þ -doped materials can be obtained by processing the fluorescence intensity ratio (FIR) of the two green emissions from these two excited states 2 H 11/2 and 4 S 3/2 to the ground state 4 I 15/2 level. Recently, the UCL and temperature sensing properties of Er 3 þ /Yb 3 þ co-doped NaYF 4 has been extensively studied [11,12]. However, there is no such knowledge about which one amongst these two phases NaYF 4 :Er 3 þ /Yb 3 þ crystals is better for the application in temperature sensing and which one has a better stability of temperature dependent UCL.…”