In this work, the thermal sensing capability of Nd 3+ -doped Y 3 Al 5 O 12 nanoparticles fabricated by combustion synthesis is reported. Under excitation at 808 nm, the relative intensity of the two spectrally isolated luminescence peaks located at around 940 nm (corresponding to a 4 F 3/2 → 4 I 9/2 transition of the Nd 3+ ions) is found to be markedly temperature-dependent allowing for ratiometric luminescence nanothermometry. The potential use of neodymium-doped yttrium aluminum garnet nanoparticles in nanothermometry has been successfully tested in a variety of systems including integrated microelectronics, optofl uidic devices, and subtissue ex vivo experiments.

The spectroscopic properties of different infrared-emitting neodymium-doped nanoparticles (LaF 3 :Nd 3þ , SrF 2 :Nd 3þ , NaGdF 4 : Nd 3þ , NaYF 4 : Nd 3þ , KYF 4 : Nd 3þ , GdVO 4 : Nd 3þ , and Nd:YAG) have been systematically analyzed. A comparison of the spectral shapes of both emission and absorption spectra is presented, from which the relevant role played by the host matrix is evidenced. The lack of a "universal" optimum system for infrared bioimaging is discussed, as the specific bioimaging application and the experimental setup for infrared imaging determine the neodymiumdoped nanoparticle to be preferentially used in each case. V C 2015 AIP Publishing LLC.

Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: El acceso a la versión del editor puede requerir la suscripción del recurso Access to the published version may require subscription properties of neodymium ions in NdVO4 and of the high neodymium content) as well as to their ultrasmall size that leads to large non-radiative decay rates. Results included in this work introduce to the scientific community ultrasmall NdVO4 stoichiometric nanoparticles as multifunctional photothermal agents that could be considered as an alternative to traditional systems such as metallic, organic or carbon-based nanoparticles.