# The Optimization of the Luminescence Intensity Ratio in the YVO4:Er3+,Nd3+ Phosphors within the First and Second Biological Windows

## TL;DR

This paper shows how adjusting the particle size of YVO4:Er3+,Nd3+ phosphors improves their ability to measure temperature accurately in biological applications.

## Contribution

The study introduces particle size optimization in YVO4:Er3+,Nd3+ phosphors to enhance luminescent thermometry performance in biological windows.

## Key findings

- YVO4:Er3+,Nd3+ phosphors show relative sensitivity values from 1.32 ± 0.02 to 1.80 ± 0.02% K–1 at 293 K.
- Temperature uncertainties are below 0.7 K within the physiological range of 293–233 K.
- The performance is achieved using luminescence intensity ratios from Er3+ and Nd3+ emissions.

## Abstract

The optimization of the host materials is one of the
methods that
could be used to improve the relative sensitivity of luminescent thermometers.
Here, we show the host optimization emission of Er3+ and
Nd3+ ions in the YVO4 phosphors produced by
a modified sol–gel route using glucose as a polymerizing agent.
X-ray diffraction (XRD) was realized to analyze the formation of the
crystalline phase. We found that the emission ratio depends on the
size of the YVO4 particle. Here, we show that YVO4:Er3+,Nd3+ phosphors exhibit particle size-dependent
relative sensitivity values, varying from 1.32 ± 0.02 to 1.80
± 0.02% K–1 at 293 K, and temperature uncertainties
below 0.7 K within the physiological range 293–233 K, operating
entirely in the first and second biological windows. These sensitivity
and temperature uncertainty values were achieved by defining two thermometric
parameters as the luminescence intensity ratios, exploiting a combination
of emissions from both ion species.