近日，中国科学院理化技术研究所康雷团队报道了阴离子基元环状排列的REXCO₃（RE = La, Ce, Y; X = OH, F）产生优异非线性光学效应。2025年12月11日，《结构化学》杂志发表了这一成果。

具有高效频率转换能力的非线性光学晶体对于全固态激光器至关重要，探索新的二次谐波产生增强策略对非线性光学晶体的结构-性能关系研究及应用具有关键意义。传统策略主要聚焦于诱导非线性光学活性单元的平行排列。

研究组通过实验表征与第一性原理计算，在阴离子基团呈环形排列的稀土碳酸盐REXCO₃（RE=La, Ce, Y; X=OH, F）体系中，发现了两种新的调控机制——键极化和柔性变形。它们分别以电子极化和多面体畸变的形式增强二次谐波产生效应。这些调控机制打破了“仅当碳酸盐基团平行排列时才能有效实现超极化率叠加并产生显著二次谐波效应”的普遍认知。通过实现环形排列与稀土多面体的协同作用，在设计的C2_La₂O₂CO₃结构中，RE-O配位键的极化率与柔性伸缩能力得到有效发挥。研究组揭示了稀土碳酸盐中二次谐波增强的新机制，并为设计先进非线性光学材料提供了新思路。

附：英文原文

Title: REXCO3 (RE = La, Ce, Y; X = OH, F) with circular alignment of anionic motifs induced extraordinary nonlinear optical effects

Author: anonymous

Issue&Volume: 2025-12-11

Abstract: Nonlinear optical (NLO) crystals with efficient frequency conversion are essential for all-solid-state lasers, and exploring new second harmonic generation (SHG) enhancing strategy is crucial for the structure-property relationship research and application of NLO crystals. Conventional strategies focus on inducing parallel alignment of NLO active units. In this work, two new regulation means, i.e. bond polarization and flexible deformation, have been identified in rare earth carbonates REXCO3 (RE = La, Ce, Y; X = OH, F) with anionic motifs circular aligned through experimental characterization and first-principles calculations. They can promote the SHG effect in the form of electronic polarization and polyhedra distortion, respectively. Such regulation methods break the common acceptation that only carbonates aligning in a parallel pattern can effectively achieve the superposition of hyperpolarizabilities and result in considerable SHG effect. By realizing the synergistic effect of circular alignment and rare earth polyhedra, the polarizability and flexible stretching ability of the RE-O coordination bonds are effectively exerted in the designed structure, C2_La2O2CO3. This work unveils a new mechanism for SHG enhancement in rare earth carbonates and provides new insight for designing advanced NLO materials.

DOI: 10.1016/j.cjsc.2025.100844

Source: https://cjsc.ac.cn/cms/issues/942