An experimental study on SrB₄O₇:Sm²⁺ as a pressure sensor

A pressure sensor of SrB₄O₇:Sm²⁺ has been synthesized and the pressure shift of its ⁷D₀-⁵F₀ fluorescence line has been recalibrated at room temperature up to 48 GPa and 127 GPa hydrostatically and non-hydrostatically, respectively. Different from previous study, our results show that the calibrated relation in the quasi-hydrostatic pressure environment is quite different from that in the non-hydrostatic pressure environment. The yield strength of SrB₄O₇:Sm²⁺ as a function of the pressure has been determined by the pressure gradient method in a diamond anvil cell. The results show that the yield strength of SrB₄O₇:Sm²⁺ increases from 2.85 GPa at a pressure of 7.9 GPa to 4.22 GPa at 25.4 GPa and is much smaller than that of ruby. The relatively small high-pressure yield strength of SrB₄O₇:Sm²⁺ is at the same level of the most sample materials. This would result in a small pressure difference with the coexisting sample, thus lead to a small error in the pressure measurement. The smaller yield strength and excellent fluorescent spectral characters of SrB₄O₇:Sm²⁺ make it a good substitute for ruby as a pressure scale in high-pressure experiments, especially under non-hydrostatic pressure environments.