Nickel-Related Centers in HPHT Microdiamonds for Near-Infrared Luminescent Thermometry

Nano- and microcrystals of diamond are attractive for optical thermometry applications and possess unique optical properties as well as high chemical stability and biocompatibility. For biological application, there are interests of diamonds with color centers that emit in the biological transparency window. One such defect is nickel-related color centers that radiate in the near-infrared range (1.4 eV Ni centers), but have not yet been sufficiently investigated. In this study, the optical characteristics of high-pressure high-temperature (HPHT) diamond microcrystals with average sizes of 4 and 30 & mu;m containing 1.4 eV Ni centers are reported. The temperature dependence of the spectral and temporal properties of Ni center emissions in the range from room temperature to 85 & DEG;C is demonstrated and thereby the possibility of appliance these centers as temperature sensors. The relative temperature sensitivities of luminescence peak intensity and lifetime for Ni centers are found to be 1.3% K-1 and 0.42% K-1, respectively. Moreover, the temperature determination accuracy reaches better than 1 K. In the study, temperature dependence of luminescence spectral and lifetime properties of 1.4 eV Ni centers in microdiamonds is revealed. It is proposed that the main reason for temperature-dependent emission rate is thermal population of higher energetic level with a faster decay rate. The obtained results are useful for luminescence thermometry in such applications as nanoelectronics, engineering, nanophotonics, and biomedicine.image & COPY; 2023 WILEY-VCH GmbH