Structural and optical properties of thermal decomposition assisted Gd2O3:Ho3 +/Yb3 + upconversion phosphor annealed at different temperatures

• The Gd2O3:Ho3+ (0.2 mol %)/Yb3+ (3 mol %) phosphor material is synthesized via two different routs.
• The effect of annealing on structural and optical properties of thermal decomposition assisted sample have been studied.
• The effect of Ho3+/Yb3+ on the structural parameters of Gd2O3 host have been studied through the Rietveld refinement of XRD data.
• The change in internal temperature through 980 nm excitation for different annealed samples was calculated theoretically.
• The temperature sensing ability of 1000°C annealed thermal decomposition assisted sample was conformed.

The infrared to visible upconversion fluorescent nanoparticles of Ho3 +/Yb3 + codoped Gd2O3 phosphor is synthesized via thermal decomposition route. The as-synthesized sample was annealed at 800, 1000 and 1200 °C for 3 h and then structural and optical properties were studied. The Rietveld refinement of X-ray diffraction (XRD) data was analyzed to probe the effect of Ho3 +/Yb3 + dopant on the structural parameters of Gd2O3 host. The upconversion emission spectra of as-synthesized and annealed samples are compared using 980 nm diode laser excitation and five emission bands noticed at 490, 539, 550, 667 and 757 nm corresponding to the 5F3 → 5I8, 5F4 → 5I8, 5S2 → 5I8,5F5 → 5I8 and 5I4 → 5I8 manifolds, respectively. The local temperature induced by laser light is also calculated. The fluorescence intensity ratio (FIR) of two thermally coupled transitions 5F4 → 5I8 and 5S2 → 5I8 is plotted against the sample temperature and sensor sensitivity of sample is calculated.

The thermal decomposition assisted Ho3 +/Yb3 + doped/co-doped Gd2O3 upconversion phosphor material have been synthesized and annealed at different temperatures 800, 1000 and 1200 °C for 3 h. The change in structural parameters due to doping of Ho3 +/Yb3 + rare earth ions in Gd2O3 host were studied through Rietveld refinement. The effects of annealing on the upconversion emission intensity were studied through temperature dependence study due to 980 nm excitation. The changes in local temperature of the samples due to laser excitation were calculated theoretically for all samples and its effects on upconversion luminescence intensity were also studied. The variation of florescence intensity ratio (FIR) with pump power density of excitation was confirmed that the present sample is suitable for temperature sensing devices with a good sensor sensitivity of 4.3 × 10− 3 K− 1 at 300 K.Figure optionsDownload as PowerPoint slide