IMPROVED CALIBRATION OF THE SRB4O7-SM2- ADVANTAGES AT VERY HIGH-PRESSURES AND HIGH-TEMPERATURES( OPTICAL PRESSURE GAUGE )

This paper presents a new calibration of the pressure shift of the D-7 (0)-F-5(0) fluorescence line of SrB4O7:Sm2+, in hydrostatic medium (he lium) up to 124 GPa and in nonhydrostatic medium (H2O) up to 130 GPa. There is no quenching of the luminescence, in contrast to that observe d in similar compounds. We show that this line permits more accurate p ressure measurements at very high pressure than the commonly used R-1 emission line of ruby because it remains intense, sharp, well isolated from the other lines, and weakly dependent on nonhydrostaticity. The wavelength pressure shift of the D-7(0)-F-5(0) line is found to be ver y well represented by the nonlinear relation: P = 4.032 Delta lambda(1 + 9.29 x 10(-3)Delta lambda)/(1 + 2.32 x 10(-2)Delta lambda) with P i n GPa and Delta lambda = lambda - 685.41 in nm. High temperature exper iments up to 900 K at room pressure were also performed. The negligibl e temperature dependence and the small thermal line broadening are fur ther advantages for high pressure-high temperature studies in diamond anvil cells. A metrology for in situ measurements of pressure and temp erature, based on the combined use of this compound with ruby is also presented, along with a new calibration of the ruby R-1 frequency shif t with temperature from 300 to 800 K. (C) 1997 American Institute of P hysics.