Influence of silica surface coating on optical properties of Er 3+ -Yb 3+ :YMoO 4 upconverting nanoparticles

Effect of Bi3+ ion on upconversion-based induced optical heating and temperature sensing characteristics in the Er3+/Yb3+ co-doped La2O3 nano-phosphor

“…The induced optical heating in the Er 3+ /Yb 3+ co-doped phosphors have been widely studied by different groups of researchers in different host materials. [4][5][6]19 They have measured the emission intensity of the thermally coupled levels ( 2 H 11/2 and 4 S 3/2 ) of the Er 3+ ion at various pump powers and observed a change in emission intensities of the two bands arising from them to a common lower level. We have monitored the emission intensities for the two emission bands of Er 3+ ion in the Er 3+ /Yb 3+ /5Bi 3+ tri-doped La 2 O 3 phosphor at various pump powers of 976 nm excitation and they are shown in Fig.…”

“…523 and 548 nm wavelengths differs from each other at room temperature. [4][5][6][24][25][26][27] Initially, the emission intensity of 523 nm band is less than that of 548 nm band at 300 K (see Fig. 13(a)).…”

“…Upconversion-based lanthanide spectroscopic studies have become a fascinating area of research in recent years due to its wide applications in various related elds, such as optical devices, optical heaters, photo-thermal treatment, temperature sensors, bio-imaging, etc. [1][2][3][4][5][6][7][8][9] The thermally coupled energy levels in some of the lanthanide ions are of great scientic importance as they can sense a small change in the temperature around them even at a distance without any contact. [4][5][6]10 These thermally coupled energy levels produce optical heating as well as being used for temperature sensing in the lanthanide doped phosphor materials.…”

“…This energy gap can be covered by the phonon energy of the host lattice. [4][5][6]11 The population of the ions in these two levels strongly depends on the phonon energy of the host. Thus, this causes a variation in intensity of the emitted bands from the thermally coupled levels in the Er 3+ /Yb 3+ co-doped phosphor materials with increase in the pump power and temperature, thereby gives a dual characteristic such as optical heating and temperature sensing.…”

“…The optical heating and temperature sensing abilities of the Er 3+ / Yb 3+ co-doped phosphors have also been investigated in different host materials. [4][5][6]11,19,[21][22][23] They have reported that the FIR is host dependent and the material with low phonon frequency can sustain better FIR with the pump power and temperature.…”