Temperature sensing using bulk and nanoparticles of Ca_0.79Er_0.01Yb_0.2MoO₄ phosphor

Abstract

Optical temperature sensing is widely realized by using upconversion (UC) emission in lanthanide-doped phosphors. There are so many various parameters that are responsible for UC intensity of the phosphor like particle shape and size, type of symmetry that exist at the site position, distribution of lanthanide ions in the phosphor, and so on. However, a comparative study of the bulk and nanostructure on the temperature sensing ability of such phosphor is rare. In the present work, we have taken Ca0.79Er0.01Yb0.2MoO4 phosphors as a model system and synthesized its bulk (via solid-state reaction method, named SCEY) and nanostructures (via solution combustion route, named CCEY). We further studied their phase, crystal structure, phonon frequency, optical excitation, and emission (upconversion & downshifting) properties. Finally, the optical temperature sensing behavior of SCEY and CCEY, in the range 305 K - 573 K, have been compared. The maximum relative sensitivity of the phosphor SCEY and CCEY are 0.0061 K-1 at 305 K and 0.0094 K-1 at 299 K, respectively, while, the maximum absolute sensitivities are 0.0150 K-1 at 348 K, and 0.0170 K-1 at 398 K, respectively. We thus conclude that the temperature sensing ability of nanoparticle-based Ca0.79Er0.01Yb0.2MoO4 phosphor is better compared to its bulk phosphor.

Enhancing the temperature sensing property of a Ca0.79−xBixEr0.01Yb0.2MoO4 phosphor via local symmetry distortion and reduction in non-radiative channels

“…40 The spherical particles of the phosphor were found to agglomerate in different orientations which is the characteristic property with combustion synthesized oxide phosphors. 8–10…”

“…The bending vibration of H–O–H is indicated by the peaks observed at 1608 cm −1 , while the stretching vibration of O–H groups is evidenced by the peak observed at 3451 cm −1 . 10,44 A minor peak observed at 2347 cm −1 specifies the stretching vibration of the C–H group. 45 The fingerprint region is characterized by two prominent vibrational bands of the [MoO 4 ] 2 .…”

“…2. 10 Similarly, some of the bond angles formed among the Ca, Mo, and O-atoms are also summarized in Table 2.…”

“…40 The spherical particles of the phosphor were found to agglomerate in different orientations which is the characteristic property with combustion synthesized oxide phosphors. [8][9][10] Energy dispersive X-ray spectroscopy (EDS) patterns of CMEY and CMBEY phosphor samples were also obtained. The EDS spectrum of CMBEY, shown in Fig.…”

“…Er 3+ , Tm 3+ , Nd 3+ , Eu 3+ , and Ho 3+ ), Er 3+ has been widely used as an activator for FIR studies [6][7][8][9] because of its suitable TCELs ( 2 H 11/2 and 4 S 3/2 ) of energy difference (∼350-700 cm −1 ). 10 However, since the quantum yield of lanthanide based upconversion emission is low, therefore, a lot of effort is still being devoted to enhance the upconversion (UC) emission at the rst step and eventually enhance the sensing ability of the lanthanides thereof.…”