Hydroxyl-Driven Enhanced Birefringence in Borophosphates

Xia Yang; Wenbin Zhang; Xueting Pan; Xueling Hou; Shujuan Han

doi:10.1021/acs.inorgchem.3c03394

Hydroxyl-Driven Enhanced Birefringence in Borophosphates

Inorg Chem. 2023 Dec 11;62(49):20430-20438. doi: 10.1021/acs.inorgchem.3c03394. Epub 2023 Nov 22.

Authors

Xia Yang^{1

2}, Wenbin Zhang^{1

2}, Xueting Pan¹, Xueling Hou^{1

2}, Shujuan Han^{1

2}

Affiliations

¹ Research Center for Crystal Materials, CAS Key Laboratory of Functional Materials and Devices for Special Environments, Xinjiang Technical Institute of Physics & Chemistry, CAS, 40-1 South Beijing Road, Urumqi 830011, China.
² Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.

PMID: 37992320
DOI: 10.1021/acs.inorgchem.3c03394

Abstract

Borophosphates have become promising candidates for ultraviolet or deep-ultraviolet functional crystals. Through high-temperature solution method, four new borophosphates, K₂B₂P₂O₉, (NH₄)₂BP₂O₇(OH), K₂BP₂O₇(OH), and P2₁/c-(NH₄)₂B₂P₃O₁₁(OH), were acquired successfully. Single crystal X-ray diffraction suggests that K₂B₂P₂O₉, (NH₄)₂BP₂O₇(OH), and K₂BP₂O₇(OH) belong to the noncentrosymmetric space group, while P2₁/c-(NH₄)₂B₂P₃O₁₁(OH) belongs to the centrosymmetric compound. It is worth mentioning that K₂B₂P₂O₉, (NH₄)₂BP₂O₇(OH), and K₂BP₂O₇(OH) present the new fundamental building blocks [B₂P₂O₁₁], [BP₂O₁₀H], and [BP₂O₉(OH)], respectively, as far as we know. Compared with K₂B₂P₂O₉, (NH₄)₂BP₂O₇(OH), K₂BP₂O₇(OH), and P2₁/c-(NH₄)₂B₂P₃O₁₁(OH) exhibit a larger optical anisotropy, further confirming the positive effect of hydroxyl groups on birefringence. UV-vis-NIR diffuse reflectance spectra display that K₂B₂P₂O₉ and (NH₄)₂BP₂O₇(OH) have short UV cutoff edges. Meanwhile, theoretical calculations were conducted to comprehend their optical properties and electronic structures.