Compressibility and High-Pressure Structure of CaMg2Bi2 and YbMg2Bi2
Abstract
Compounds with the formula AM2X2 in the CaAl2Si2 structure type have garnered increasing interest across various solid-state research domains, such as quantum topological and thermoelectric materials. Prior studies have identified high-pressure phase transitions in several compounds, including Mg3Sb2, Mg3Bi2, CaMn2Bi2, and SrAl2Si2. In this study, we investigate the structural behavior of CaMg2Bi2 and YbMg2Bi2 under varying pressure conditions. We synthesized crystals using the molten metal flux method and examined them through single-crystal synchrotron X-ray diffraction, employing diamond anvil cells to exert pressures up to 20 GPa. Our analysis reveals insights into the anisotropic compressibility of these materials, highlighting the more compressible and flexible octahedral A-Bi bonds as the primary contributors to this anisotropy. Moreover, we observed a phase transition in both CaMg2Bi2 and YbMg2Bi2 at pressures above 9.6 GPa and 8.7 GPa, respectively. The newly identified high-pressure phase exhibits a distortion of the original CaAl2Si2 structure with space group C2/m. This high-pressure structure is distinct from that of related compounds (e.g., CaMn2Bi2, MgMg2Bi2), the latter exhibiting a square pyramidal coordination for the M site.
Versions
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BibTeX
@misc{calderoncueva2026compressibility,
title = {{Compressibility and High-Pressure Structure of CaMg$_2$Bi$_2$ and YbMg$_2$Bi$_2$}},
author = {Mario Calderón-Cueva and Allison Pease and Cheng Peng and Wanyue Peng and Megan Rylko and Weiwei Xie and Susannah M. Dorfman and Alexandra Zevalkink},
howpublished = {arXiv},
year = {2026},
month = jun,
doi = {10.48550/arxiv.2606.00785},
eprint = {2606.00785},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.00785},
}
RIS
TY - UNPB
TI - Compressibility and High-Pressure Structure of CaMg_2Bi_2 and YbMg_2Bi_2
AU - Mario Calderón-Cueva
AU - Allison Pease
AU - Cheng Peng
AU - Wanyue Peng
AU - Megan Rylko
AU - Weiwei Xie
AU - Susannah M. Dorfman
AU - Alexandra Zevalkink
PY - 2026
DA - 2026/06/01
PB - arXiv
DO - 10.48550/arxiv.2606.00785
UR - https://arxiv.org/abs/2606.00785
AB - Compounds with the formula AM_2X_2 in the CaAl_2Si_2 structure type have garnered increasing interest across various solid-state research domains, such as quantum topological and thermoelectric materials. Prior studies have identified high-pressure phase transitions in several compounds, including Mg_3Sb_2, Mg_3Bi_2, CaMn_2Bi_2, and SrAl_2Si_2. In this study, we investigate the structural behavior of CaMg_2Bi_2 and YbMg_2Bi_2 under varying pressure conditions. We synthesized crystals using the molten metal flux method and examined them through single-crystal synchrotron X-ray diffraction, employing diamond anvil cells to exert pressures up to 20 GPa. Our analysis reveals insights into the anisotropic compressibility of these materials, highlighting the more compressible and flexible octahedral A-Bi bonds as the primary contributors to this anisotropy. Moreover, we observed a phase transition in both CaMg_2Bi_2 and YbMg_2Bi_2 at pressures above 9.6 GPa and 8.7 GPa, respectively. The newly identified high-pressure phase exhibits a distortion of the original CaAl_2Si_2 structure with space group C2/m. This high-pressure structure is distinct from that of related compounds (e.g., CaMn_2Bi_2, MgMg_2Bi_2), the latter exhibiting a square pyramidal coordination for the M site.
ER -