Thermal dissolution of Eu2+ Suzuki phase nanostructures in KBr crystals monitored by pulsed photoacoustic and photoluminescence techniques

Suzuki-type precipitated phases are nanostructures that change the optical and mechanical properties of the crystal in which they have been formed. The dissolution process of the Europium Suzuki phase (SP) nanostructures was induced by continuous heating (1 °C/min) of KBr:Eu2+ single crystals and it was simultaneously monitored by two techniques: photoacoustic (PA) and photoluminescence (PL). Each sample was heated from room temperature to 205 °C; meanwhile a focused laser pulse (355 nm) impinged on one crystal face to excite the low energy Europium absorption band and generate the photoacoustic signal. The correlation coefficients between subsequent PA signals were used to build a thermal profile and its behaviour was found to be directly related with the absorption coefficient of Eu2+ ion in its crystalline environment. From correlation analysis and Fourier fast transform (FFT) applied to the PA signal data, the dynamical thermal dissolution process has been studied and compared with simultaneous emission spectrum data obtained by the PL technique. The results show good agreement with the literature.