American Geophysical Union (AGU) Acta Medica Okayama 0094-8276 52 14 2025 Unraveling the Complex Features of the Seismic Scatterers in the Mid‐Lower Mantle Through Phase Transition of (Al, H)‐Bearing Stishovite e2024GL114146 EN Yingxin Yu Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China Youyue Zhang Institute for Planetary Materials, Okayama University Luo Li Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China Xinyue Zhang Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China Denglei Wang Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China Zhu Mao Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China Ningyu Sun Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China Yanyao Zhang Earth and Planetary Sciences, Stanford University Xinyang Li State Key Laboratory of High Pressure and Superhard Materials, College of Physics, Jilin University Wancai Li CAS Key Laboratory of Crust‐Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China Sergio Speziale GFZ German Research Centre for Geosciences Dongzhou Zhang GeoSoilEnviroCARS, University of Chicago Jung‐Fu Lin Department of Earth and Planetary Sciences, Jackson School of Geosciences, The University of Texas at Austin Takashi Yoshino Institute for Planetary Materials, Okayama University Small-scale scatterers observed in the mid-lower mantle beneath the subduction zones are thought to result from the phase transition of stishovite within subducted oceanic crusts. Here we investigate the phase transition of (Al, H)-bearing stishovite with four compositions at simultaneously high P-T conditions combining Raman spectroscopy and X-ray diffraction. These experimental results reveal that the incorporation of 0.01 a.p.f.u Al into stishovite with H/Al ratio of ∼1/3 lowers the transition pressure by 6.7(3) GPa. However, the Clapeyron slope of this transition is nearly unaffected by changes in the Al content and has a value of 12.2–12.5(3) MPa/K. According to our results, Al content variation ranging from 0 to 0.07 a.p.f.u in SiO2 can reasonably explain the depth distribution from 800 to 1,900 km of the seismic scatterers observed in the circum-Pacific region. These results deepen our understanding on the complex features of mid-lower mantle seismic scatterers and corresponding dynamic processes. No potential conflict of interest relevant to this article was reported.