title: Wide-Range Thermometry at Micro/Nano Length Scales with In2O3 Octahedrons as Optical Probes.
abstract: We report the temperature-dependent photoluminescence and Raman spectra of In2O3 octahedrons synthesized by an evaporation-condensation process. The luminescence obtained here is due to the defect-related deep level emission, which shows highly temperature-dependent behavior in 83-573 K range. Both the position as well as the intensity varies with temperature. Similarly, Raman spectroscopy in 83-303 K range shows temperature-dependent variation in peak intensity but no change in the peak position. Interestingly, the variation of intensity for different peaks is consistent with Placzek theory which invokes the possibility of temperature sensing. We demonstrate the reversibility of peak intensity with temperature for consecutive cycles and excellent stability of the octahedrons toward cryogenic temperature sensing. Overall, both the temperature-dependent photoluminescence and Raman spectra can be explored to determine temperature in the cryogenic range at micro/nano length scales. As an example, we evaluate the temperature-dependent Raman spectra of WO3 that undergoes a phase transition around 210 K and temperature-dependent luminescence of Rhodamine 6G (Rh6G) where intensity varies with temperature.
authors.affiliation: Materials Research Centre, Indian Institute of Science , Bangalore-560012, India.
authors.forename: Subrata
authors.initials: S
authors.lastname: Senapati
authors.affiliation: Materials Research Centre, Indian Institute of Science , Bangalore-560012, India.
authors.forename: Karuna Kar
authors.initials: KK
authors.lastname: Nanda
keywords: In2O3 octahedrons; Raman spectroscopy; WO3 phase transition; defect emissions; optical thermometry