中国物理B ›› 2025, Vol. 34 ›› Issue (8): 86102-086102.doi: 10.1088/1674-1056/add4e1
所属专题： SPECIAL TOPIC — Structures and properties of materials under high pressure
Structural evolution and bandgap modification of a robust mixed-valence compound Eu9MgS2B20O41 under pressure
Boyang Fu(符博洋)1, Wenfeng Zhou(周文风)2, Fuyang Liu(刘扶阳)3, Luhong Wang(王鲁红)4, Haozhe Liu(刘浩哲)3, Sheng-Ping Guo(郭胜平)5,†, and Weizhao Cai(蔡伟照)1,‡
- 1 School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, China;
2 School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China;
3 Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China;
4 Shanghai Advanced Research in Physical Sciences, Shanghai 201203, China;
5 Yunnan Key Laboratory of Electromagnetic Materials and Devices, National Center for International Research on Photoelectric and Energy Materials, School of Material and Energy, Yunnan University, Kunming 650091, China
Structural evolution and bandgap modification of a robust mixed-valence compound Eu9MgS2B20O41 under pressure
Boyang Fu(符博洋)1, Wenfeng Zhou(周文风)2, Fuyang Liu(刘扶阳)3, Luhong Wang(王鲁红)4, Haozhe Liu(刘浩哲)3, Sheng-Ping Guo(郭胜平)5,†, and Weizhao Cai(蔡伟照)1,‡
- 1 School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, China;
2 School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China;
3 Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China;
4 Shanghai Advanced Research in Physical Sciences, Shanghai 201203, China;
5 Yunnan Key Laboratory of Electromagnetic Materials and Devices, National Center for International Research on Photoelectric and Energy Materials, School of Material and Energy, Yunnan University, Kunming 650091, China
摘要： The recently discovered mixed-valence compound Eu$_{9}$MgS$_{2}$B$_{20}$O$_{41}$ is composed of triple-kagomé-layers separated by nonmagnetic Mg$^{2+}$ ions, and intervalence charge transfer has been observed in the mixed Eu$^{2+}$ and Eu$^{3+}$ ions within the kagomé layers, exhibiting similar characteristics typical of a quantum spin liquid. In this study, high-pressure in situ x-ray diffraction measurements on Eu$_{9}$MgS$_{2}$B$_{20}$O$_{41}$ were conducted within the range of 0.1 MPa to 64.4 GPa. The results revealed that the stabilization of the ambient-pressure phase, with no transition from mixed valence to single valence observed within the studied pressure range. The bulk modulus of the sample was determined to be 167.3(28) GPa and 180.8(17) GPa, for the single-crystal and powder x-ray diffraction data at room temperature, respectively. These values correspond to approximately 40% of the bulk modulus of diamond. Moreover, absorption spectroscopy measurements were carried out up to 37.9 GPa, revealing a $\sim 20$% reduction in the energy band gap, mainly due to the shortened Eu-O bond lengths. The relationship between pressure and band gap demonstrates a nearly linear trend, with a slope of $-0.013$ eV/GPa. The findings of the present study imply that the studied sample demonstrates considerable robustness under extreme pressures.
中图分类号: (X-ray diffraction)
- 61.05.cp