title: Upconversion emission of BaTiO3:Er3+ nanocrystals: influence of temperature and surrounding medium.
abstract: Here, we report the role of crystallite size and surrounding medium on the upconversion emission of Er3+ in BaTiO3 oxide nanocrystals. The samples were prepared by sol-emulsion-gel method and heat-treated at two different temperatures yielding powders containing nanoparticles of different sizes. Green (550 nm) and red (660 nm) upconversion emission were observed at room temperature from the 4S3/2 and 4F9/2 levels of BaTiO3:Er3+ nanocrystals. The pump power dependence study confirms that all these upconversion emission lines are a two-photon absorption process. We observed that the luminescence lifetime is shorter for the sample containing smaller particles. Optical thermometry experiments were performed in air, water and glycerol in a temperature range from 27.1 up to 47.1 degrees C aiming to use this material as a biological temperature sensor.
authors.affiliation: Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil.
authors.forename: Glauco S
authors.initials: GS
authors.lastname: Maciel
authors.forename: Márcio A R C
authors.initials: MA
authors.lastname: Alencar
authors.forename: Cid B
authors.initials: CB
authors.lastname: de Araújol
authors.forename: Amitava
authors.initials: A
authors.lastname: Patra