SiV-containing microcrystals of diamond are synthesised by using high-pressure high-temperature treatment of a mixture of pertinent organic-inorganic precursors. Photoluminescence of SiV defects were investigated with the aim to use the microcrystals for optical temperature sensing in near infrared at room temperature based on temperaturedependent shift of the 740 nm zero-phonon line of SiV photoemission.

Herein optical properties of aggregates of hydrophobic nanodiamonds (NDs) with germanium‐vacancy (GeV) defects distributed on substrates with different hydrophilicities (bare Si or TiO2 (anatase) film on Si substrate) are investigated with an aim to achieve millimeter‐scale, nearly homogeneous spatial distribution of ND aggregates. ND aggregates are spread by drop casting of a water colloid. The luminescence spectra of GeV defects are studied in a wide temperature range (85–400 K). The possibility of optical thermometry operating in a wide temperature range also covering biotemperatures is demonstrated using a separate microaggregate of NDs on the anatase film.

SiV-containing microcrystals of diamond are synthesised by using high-pressure high-temperature treatment of a mixture of pertinent organic-inorganic precursors. Photoluminescence of SiV defects were investigated with the aim to use the microcrystals for optical temperature sensing in near infrared at room temperature based on temperature-dependent shift of the 740 nm zero-phonon line of SiV photoemission.

Diamond microcrystals containing silicon-vacancy (SiV) defects were synthesized by using a high-pressure hightemperature treatment of a mixture of pertinent organic-inorganic precursors. Photoluminescence of the SiV defects and its temperature dependence (80-400 K) were studied. A strong sharp zero-phonon line (ZPL) at 738 nm was recorded at all temperatures under 488 nm laser excitation. In particular, the thermally induced shift of the ZPL was found promising for optical temperature sensing in the near infrared spectral range at biomedically relevant temperatures.