Remarkable Near-Infrared Temperature Sensing Properties of Y₃Ga₅O₁₂:Cr³⁺ and Y₃Ga₅O₁₂:Cr³⁺/Yb³⁺ Nanotubes Fabricated via a Single-Needle Electrospinnin

For the first time, nanotubes of Y₃Ga₅O₁₂:Cr³⁺ (referred to as YGO:Cr³⁺) and Y₃Ga₅O₁₂:Cr³⁺/Yb³⁺ (referred to as YGO:Cr³⁺/Yb³⁺) were produced via a single-needle electrospinning method. The nanotubes of YGO:Cr³⁺ and YGO:Cr³⁺/Yb³⁺ have outer diameters between 190 and 210 nm, whereas the inner diameter ranges between 70 and 80 nm, and the wall thickness ranges from 50 to 60 nm. The temperature sensitivity of YGO:0.02Cr³⁺ nanotubes was examined by studying how the Cr³⁺ lifetime changes with temperature. In the temperature range of 303 to 723 K, the peak values of <i>S</i>_a and <i>S</i>_r were 0.274 and 0.0067 K^-1, respectively. Temperature sensing properties of YGO:0.02Cr³⁺/<i>y</i>Yb³⁺ (<i>y</i> = 0.01, 0.02, and 0.05) nanotubes were evaluated via the FIR technique utilizing nonthermally coupled energy levels. The <i>I</i>₉₇₀/<i>I</i>₇₀₈ in the YGO:0.05Cr³⁺/0.01Yb³⁺ nanotubes displayed a maximal S_r value of 0.013 K^-1 at 633 K, which exceeds that of other Cr³⁺-doped NIR phosphors previously reported and is promising for high-temperature measurements.