Lanthanum fluoride nanoparticles doped with Nd<sup>3+</sup> ions obtained via solvothermal method have been presented. Doped nanoparticles were prepared in two-step method. Firstly rare-earth chlorides were synthesized from oxides and then they were used to prepare LaF<sub>3</sub> particles. The luminescence spectra shows typical for crystalline materials Stark splitting at 880 nm corresponding <sup>4</sup>F<sub>3/2</sub> to <sub>4</sub>I<sub>9/2</sub> level transition and 1060 nm matching <sup>4</sup>F<sub>3/2</sub> to <sup>4</sup>I<sub>11/2</sub> level transition. The highest luminescence intensity was achieved for sample doped with 0.75% wt. of Nd<sup>3+</sup>, and the longest decay time for sample doped with 0.5% wt. which reached 328 μs. The XRD pattern analysis confirmed that obtained material consists of crystalline LaF<sub>3</sub>, the grain size was estimated from Sherrer's formula and equaled about 25nm.
This paper presents a luminescence sensor for real-time pH measurements. The emission spectra of mixture consisted of tested and base solution of fluorescein is used for analysis of the pH of aqueous solutions. The proposed microfluidic mixing system with integrated optical fibers allows pH measurement in the range 7.6 – 2.8. The developed sensor can be used in automatic pH control systems that work with aqueous solutions. The optimization of fluorescein concentration in base solution allowed to obtain linear characteristic of sensor response. The practical realization of the sensor with continuous monitoring of the pH of liquids and its potential applications are presented.
In the paper the influence of luminescent layer made of tellurite glass doped with Yb<sup>3+</sup>/Er<sup>3+</sup> on parameters of
silicon photovoltaic cell in the near infrared region was investigated. Luminescence properties of the fabricated
glass under 976 nm excitation were measured. As a result of the conducted works enhancement of conversion
efficiency of NIR radiation utilizing upconversion process in tellurite glass doped with RE was obtained.
Parameters of PV cell with active layer: open circuit voltage increase of 5,5% for sample codoped with Yb<sup>3+</sup>/Er<sup>3+</sup>
system and 2,7% for sample doped with Er<sup>3+</sup>, 100% is the signal from pure PV cell illuminated by 976 nm laser.
In this paper the analysis of upconversion luminescence dynamics in tellurite and germanate glasses doped with
Ho<sup>3+</sup> and sensitized by Yb<sup>3+</sup> in 8:1 molar ratio was presented. Population of energy levels was calculated using
Runge-Kutta method. The influence of pump power (976 nm) radiation on population of excited levels and the
possible upconversion mechanisms were analyzed. The energy transfer coefficient in tellurite glass C<sub><sup>D2</sup></sub> = 5,0 x
10<sup>-18</sup> cm<sup><sup>3</sup></sup>/s, C<sub>D3</sub> = 1,5 x 10<sup>-17</sup> cm<sup>3</sup>/s and C<sub><sub>D4</sub></sub> = 9,0 x 10<sup><sup>-17</sup></sup> cm<sup>3</sup>/s and in germanate glass C<sub>D2</sub> = 2,80 x 10<sup>-18</sup> cm<sup>3</sup>/s,
C<sub>D3</sub> = 6,35 x 10<sup>-18</sup> cm cm<sup>3</sup>/s and C<sub>D4</sub> = 3,56 x 10<sup>-17</sup> cm<sup>3</sup>/s were used to analyze dynamics of upconversion processes.