A new type of near infrared absorbing near infrared emitting (NANE) luminescent nanothermometer is presented, whose physical background relies on efficient and temperature dependent Nd³⁺ to Yb³⁺ energy transfer under 808 nm photo-excitation.

Laser induced white light emission was observed from porous graphene foam irradiated with a focused continuous wave beam of the infrared laser diode. It was found that the intensity of the emission increases exponentially with increasing laser power density, having a saturation level at ca. 1.5 W and being characterized by stable emission conditions. It was also observed that the white light emission is spatially confined to the focal point dimensions of the illuminating laser light. Several other features of the laser induced white light emission were also discussed. It was observed that the white light emission is highly dependent on the electric field intensity, allowing one to modulate the emission intensity. The electric field intensity ca. 0.5 V/μm was able to decrease the white light intensity by half. Origins of the laser-induced white light emission along with its characteristic features were discussed in terms of avalanche multiphoton ionization, inter-valence charge transfer and possible plasma build-up processes. It is shown that the laser-induced white light emission may be well utilized in new types of white light sources.

The laser induced white emission (LIWE) from Sr ₂ CeO ₄ nanocrystals upon irradiation with a focused IR laser beam was investigated.

This paper focuses on the kinetics of Cr⁴⁺ formation in Cr,Ca:YAG ceramics prepared by solid-state reaction sintering. The kinetics of Cr⁴⁺ formation was studied by annealing of Cr,Ca:YAG ceramics in ambient air under different temperatures at different times, resulting in the transformation of Cr³⁺ to Cr⁴⁺. The activation energy (E_a) of Cr³⁺ oxidation determined by the Jander model was 2.7 ± 0.2 eV, which is in good correlation with the activation energy of innergrain oxygen diffusion in the YAG lattice. It is concluded that Cr³⁺ to Cr⁴⁺ transformation in YAG ceramics is limited by oxygen diffusion through the grain body. It was established that in Cr,Ca:YAG ceramics, the intralattice cation exchange, in which the Cr⁴⁺ ions exchange positions with the Al³⁺ ions, switching from “A” to “D” sites, is faster than Cr³⁺ to Cr⁴⁺ oxidation. In the temperature range of 900–1300 °C, the reaction enthalpy of Al³⁺/Cr⁴⁺ ion exchange between octahedral “A” and tetrahedral “D” lattice sites is close to zero, and this exchange ratio is thermodynamically driven by entropy.