Search

Detailed investigations of the photoluminescence properties of Mn4+ (3d3) ions in YAlO3 have been performed in the temperature range 10–600 K. The luminescence of Mn4+ ions due to the transition consists of two zero-phonon lines (R lines) at 691.3 and 692.7 nm, which became visible only at low temperature, and their vibronic sidebands that cover the range of 660–740 nm. The thermal quenching of the luminescence intensity due to the non-radiative decay occurs at temperatures above 420 K. The temperature dependence of the luminescence decay time shows a quasi-linear decrease from τ = 4.9 to 1.6 ms in the temperature range from 90 to 420 K (with a temperature coefficient −0.01 ms K−1) that makes YAlO3:Mn a potentially good phosphor for a fibre optic fluorescence thermometer in this temperature range. The high-pressure low-temperature luminescence measurements in a diamond-anvil cell reveal similar pressure coefficients for Mn4+ and Cr3+ dopant ions in YAlO3, equal to 1.16 cm−1 kbar−1 and 1.08 cm−1 kbar−1, respectively.

We present results of a high-pressure photoluminescence study of Mn- and Ca-doped gadolinium gallium garnet (GGG) crystals. Since the Mn4+ ion has the same electronic structure of the open 3d3 shell as Cr3+, its spectroscopic properties are expected to be similar to those of the Cr-doped GGG. We observed the luminescence R-lines of various Mn4+ centres in GGG. In the 0–118 kbar pressure range those R-lines shift linearly to lower energies. The pressure coefficients are of the order of 2 cm−1 kbar−1, about three times larger than that for Cr3+ ions. This fact can be explained by different strength of coupling of isoelectronic Cr3+ and Mn4+ ions with GGG host. The changes of the radiative decay times of the Mn4+ centres as a function of pressure are fitted with a theoretical model.

No abstract available

In this contribution we present fluorescence spectra and fluorescence decays of LLGG : Cr3+ measured at pressures up to 152 kbar. We have observed a blue shift of the broad band (4T2 →2A2) emission, with the pressure coefficient of 10 cm-1/kbar. At pressures above 100 kbar the R line related to the2E →4A2 transition is observed. Pressure dependence of the fluorescence decays have been analyzed using an adiabatic model.

Measurements include studies of effect of hydrostatic pressure, up to 80 kbar, on fluorescence spectra of ruby, especially the pressure dependence of the energy of the lines related to fluorescence of paired Cr 3+ ions. We have considered the high pressure spectroscopy experiments as effective tool for identification of the lines and investigation of the exchange interaction

Pressure-induced shift of various luminescence lines of Nd3+-doped yttrium aluminum garnet crystal in the pressure range of 0–120kbars and temperatures between 10 and 300K is reported. Spectral positions of all these lines in the region of 900–960nm shift linearly towards lower energies with the pressure coefficient values from −0.01to−0.99cm−1∕kbar in the examined pressure range. Two of these lines have similar pressure coefficients than those of the R lines of Cr3+ in ruby. Therefore, they can be readily used for pressure calibration in diamond anvil cells.