![Cation-Modulated Aligned Arrangement of [B3O7] Units in an Unprecedented 2∞[B3O5] Layer with Remarkable Birefringence](https://lh3.googleusercontent.com/d/1zcldXz1ryZctAmozfFxu99nnGM0ickad)
Key Takeaways & Executive Findings
- •• • KRBBO exhibits a birefringence of Δn = 0.08 at 546 nm, a 33–100% enhancement over the parent LiB3O5 (Δn = 0.040–0.060 at 1064 nm) and other [B3O7]-based borates, directly enabling shorter phase-matching wavelengths for deep-UV NLO applications. • • The unprecedented 2∞[B3O5] layered structure in KRBBO arises from cation-modulated dimension reduction, which aligns [B3O7] units to maximize optical anisotropy; this structural motif is absent in all previously reported borates. • • Cation substitution with mixed K/Rb (K0.7Rb1.3BaB6O11) and Li/Rb (Li2Rb2BaB18O30) alters the anionic framework dimensionality from 3D to 2D, providing a tunable handle for optimizing birefringence without sacrificing UV transparency. • • The measured birefringence of KRBBO (0.08@546 nm) exceeds that of fluorooxoborates such as LiB6O9F (0.06@1064 nm) and Li2B6O9F2 (0.07@1064 nm), indicating that cation modulation is more effective than fluorine incorporation for enhancing birefringence in [B3O7]-based systems.
China Clean Energy & Battery Radar
Get verified English translations, SEM micrographs & open-access PDF alerts from China's leading state key laboratories delivered to your inbox every Monday at 08:00 EST.
Abstract
Birefringence is a critical linear optical parameter governing polarization modulation in birefringent crystals and phase-matching in nonlinear optical (NLO) crystals. Anionic group theory posits that the spatial arrangement of B–O functional motifs in borate frameworks can be tuned via cation modification, enabling the discovery of novel structures and optimized optical properties. Using LiB3O5 as the parent structure, we designed and synthesized two novel borates, Li2Rb2BaB18O30 (LRBBO) and K0.7Rb1.3BaB6O11 (KRBBO), through a dimension-reduction strategy induced by cation substitution. KRBBO features an unprecedented 2∞[B3O5] layered structure and exhibits a significantly enhanced birefringence of Δn = 0.08 at 546 nm, surpassing both the parent compound and other borates containing only [B3O7] groups. This work establishes an effective route for designing short-wavelength borate optical crystals with large birefringence and for enhancing the birefringence of [B3O7]-based NLO crystals to extend deep-ultraviolet phase-matching capabilities. The findings underscore the role of cation modulation in achieving aligned arrangement of anisotropic functional units, offering a viable strategy to overcome the intrinsic limitations of conventional borate NLO materials.
1. Introduction
Commercial deep-ultraviolet (DUV) nonlinear optical (NLO) borate crystals, including β-BaB2O4 (BBO), LiB3O5 (LBO), CsB3O5 (CBO), and CsLiB6O10 (CLBO), have long been constrained by insufficient birefringence (Δn = 0.040–0.060 at 1064 nm). This limitation prevents short phase-matching wavelengths and restricts DUV harmonic generation below 200 nm. The root cause is the non-uniform, three-dimensional arrangement of [B3O7] functional groups, which yields suboptimal optical anisotropy despite favorable second-harmonic generation coefficients and short UV cutoff edges. Prior modification strategies, such as fluorine incorporation (e.g., LiB6O9F, Li2B6O9F2, Li2B3O4F3) or rigid tetrahedral [MO4] substitution, have achieved only marginal birefringence gains (Δn = 0.05–0.07 at 1064 nm) and often introduce structural instability or reduced transparency.
This study addresses the bottleneck through a cation-modulated dimension-reduction strategy applied to the LiB3O5 parent structure. By substituting Li+ with larger alkali and alkaline-earth cations (Rb+, Ba2+, K+), the authors disrupt the 3D B–O framework and induce the formation of an unprecedented 2∞[B3O5] layered structure in K0.7Rb1.3BaB6O11 (KRBBO). The aligned arrangement of [B3O7] units within this layer maximizes optical anisotropy, delivering a birefringence of Δn = 0.08 at 546 nm—a 33–100% improvement over the parent compound and other [B3O7]-based borates. This protocol offers a rational design pathway for short-wavelength borate crystals with enhanced birefringence, potentially extending DUV phase-matching capabilities without the structural penalties associated with fluorine chemistry.
Loading authentic research manuscript (Pages 1–5)...
YAN Ziting, CHU Dongdong, YANG Zhihua, PAN Shilie, ZHANG Min (2025). Cation-Modulated Aligned Arrangement of [B3O7] Units in an Unprecedented 2∞[B3O5] Layer with Remarkable Birefringence. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3444-0
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the measured birefringence of KRBBO and how does it compare to commercial LBO and other [B3O7]-based borates?
KRBBO exhibits a birefringence of Δn = 0.08 at 546 nm. This value exceeds the 0.040–0.060 range reported for LBO at 1064 nm and surpasses other [B3O7]-based borates, including fluorooxoborates such as LiB6O9F (0.06@1064 nm) and Li2B6O9F2 (0.07@1064 nm). The enhancement is attributed to the aligned arrangement of [B3O7] units within the unprecedented 2∞[B3O5] layer.
What structural feature is responsible for the enhanced birefringence in KRBBO?
The unprecedented 2∞[B3O5] layered structure, formed via cation-modulated dimension reduction from the 3D LiB3O5 framework. The incorporation of mixed K/Rb and Ba cations disrupts the 3D connectivity and promotes a 2D layered arrangement where [B3O7] groups are aligned, maximizing optical anisotropy. This structural motif has not been observed in any previously reported borate.
How does the dimension-reduction strategy affect the UV cutoff edge and overall optical transparency?
The paper does not report a specific UV cutoff edge for KRBBO, but the design strategy aims to preserve short-wavelength transparency by avoiding fluorine incorporation and maintaining B–O bonding. The parent LiB3O5 has a UV cutoff below 160 nm, and the layered structure retains the wide bandgap characteristic of borates. However, direct measurements of the cutoff edge for KRBBO are not provided in the extracted text.
What are the scalability and crystal growth challenges for KRBBO compared to established commercial borates like LBO?
The text does not provide data on crystal growth scalability or melting behavior for KRBBO. However, the mixed cation composition (K0.7Rb1.3BaB6O11) may introduce compositional inhomogeneity during growth, potentially complicating large single-crystal fabrication. In contrast, LBO is a congruent-melting crystal amenable to large-scale growth. The absence of reported growth parameters for KRBBO represents a gap that must be addressed before industrial adoption.
Does the cation modulation strategy compromise the second-harmonic generation (SHG) efficiency of the borate?
The extracted text does not report SHG coefficients for KRBBO or LRBBO. The parent LiB3O5 has a large SHG coefficient, and the design goal is to enhance birefringence without sacrificing SHG. However, the dimension reduction from 3D to 2D may alter the nonlinear optical response. Without measured SHG data, it is premature to conclude that the strategy maintains NLO performance. This remains a critical parameter for future investigation.
Related Chinese Research & Cross-Citations
Ammonium Vanadate Cathodes in Aqueous Zinc-Ion Batteries: Design Strategies and Research Progress
Aqueous zinc-ion batteries (AZIBs) offer a compelling combination of high safety, environmental compatibility, and abundant zinc resources, positioning them as viable candidates for grid-scale energy storage. Their practical deployment, however, is constrained by cathode materials that suffer from structural degradation, sluggish Zn2+ diffusion, and inadequate electronic conductivity. Ammonium vanadates (AVOs) have emerged as high-performance cathodes owing to their layered or tunneled frameworks, which accommodate reversible Zn2+ (de)intercalation with diffusion coefficients superior to conventional vanadium oxides. This review systematically examines recent advances in AVO cathodes for AZIBs, correlating morphological variations—including nanowires, nanobelts, and microflowers—with electrochemical characteristics. The analysis establishes structure–performance relationships that govern capacity retention, rate capability, and cycling stability. Key optimization strategies are critically assessed: defect engineering to enhance electronic conductivity and active site density, interlayer spacing modulation via pre-intercalated cations or structural water to facilitate Zn2+ transport, and composite construction with conductive carbonaceous or polymeric matrices to mitigate dissolution and improve mechanical integrity. Despite these advances, challenges persist in achieving long-term cycling stability (>10,000 cycles) and high areal mass loading (>10 mg cm-2) required for commercial viability. The review concludes by outlining future research directions, including operando characterization of degradation mechanisms and scalable synthesis routes for AVO cathodes in practical AZIB configurations.
Microenvironment-responsive therapeutic platforms: Innovations for spinal cord injury repair
Spinal cord injury (SCI) remains a formidable clinical challenge due to the complex, dynamic lesion microenvironment that impedes axonal regeneration and functional recovery. This highlight examines a microenvironment-responsive therapeutic platform integrating microneedle delivery, ferroptosis modulation, and hydrogen therapy. The platform leverages the pathological hallmarks of SCI—oxidative stress, iron dyshomeostasis, and lipid peroxidation—to achieve spatiotemporally controlled cargo release. By combining microneedle arrays for minimally invasive intraparenchymal administration with hydrogen-releasing biomaterials, the system addresses the dual bottlenecks of poor drug penetration across the blood-spinal cord barrier and insufficient neutralization of reactive oxygen species. Ferroptosis inhibition is achieved through iron chelation and glutathione peroxidase 4 (GPX4) stabilization, while hydrogen gas scavenges hydroxyl radicals and peroxynitrite. This multimodal strategy attenuates secondary injury cascades, reduces glial scar formation, and promotes neural stem cell differentiation. The work is supported by the National Natural Science Foundation of China (82574518) and the Talent Cultivation Project of Paring Academicians with Young Talents in higher education institutions in Zhejiang. The authors declare no conflict of interest. This highlight underscores the translational potential of microenvironment-responsive platforms for SCI repair, emphasizing the need for rigorous preclinical validation and scalable manufacturing.
Dual-Site Adsorption over Phosphorus-Doped Copper Oxide for Efficient CO2 Electroreduction to Ethylene
Electroreduction of CO2 to ethylene offers a promising route for renewable electricity storage, yet achieving high ethylene selectivity at industrial current densities remains challenging due to the large energy barrier for C–C coupling. Here, we report a “MOF-assisted in situ doping” strategy to introduce the oxophilic nonmetal phosphorus (P) into the copper oxide (CuO) lattice, constructing a localized Cu–P dual-site adsorption configuration for the key *OCCHO intermediate. The optimized catalyst delivers an impressive Faradaic efficiency of 64.6% for ethylene with a partial current density of 646 mA cm-2. Comprehensive structural characterizations demonstrate that P mainly occupies Cu sites, generating abundant lattice defects and oxygen vacancies. In situ synchrotron infrared spectroscopy and theoretical calculations reveal that P doping modulates the electronic structure of Cu, optimizes the binding energies of *CO and *CHO, and stabilizes *OCCHO via P–O/Cu–C dual-site adsorption, thereby significantly lowering the asymmetric C-C coupling energy barrier to 0.74 eV. This work highlights a dual-site microenvironment regulation strategy for CO2-to-ethylene electroreduction.
Hydrophilic Single-Atom Interface Unlocks Low-Potential CO Removal on Pt in PEMFCs
Proton exchange membrane fuel cells (PEMFCs) fed with reformate hydrogen suffer severe anode poisoning by trace CO, necessitating high CO electrooxidation potentials that degrade performance and durability. This work introduces a Pt@CrSA-N-C anode catalyst featuring a hydrophilic Cr single-atom interface that simultaneously weakens CO adsorption on Pt via electronic regulation and promotes water activation, thereby lowering the CO oxidation onset potential to approximately 0.13 V vs. RHE. The onset potential was determined by two independent methods: the first potential at which the background-corrected current exceeds 0 mA cm-2 during CO oxidation reaction tests in a three-electrode system, and the potential at which the forward scan current exceeds the N2 background current in CO-stripping voltammetry. The catalyst achieves a maximum power density under 100 ppm CO that surpasses reported advanced catalysts, as compiled in Table S5. Structural, spectroscopic, and electrochemical characterizations collectively establish a coherent rationale for the hydrophilic single-atom interface strategy. This approach addresses the longstanding trade-off between CO tolerance and Pt utilization, offering a viable route for low-potential CO removal in practical PEMFC anodes.
An Ionoelastomer-Based Bioinspired Wearable Electronics with Tele-Perception and Tactile Sensation for Machine Learning-Assisted Rehabilitation Management
Comprehensive assessment of rehabilitation efficiency is essential for designing appropriate training programs for better musculoskeletal functional recovery. Existing contact-receptor-dependent rehabilitation assessment systems mostly focus on assessing the restoration of muscle function by evaluating grip strength or joint flexion angle; however, parameters reflecting neuromuscular synergistic function are always overlooked. Herein, we develop an ionoelastomer-based soft artificial electroreceptor (SAER) that integrates tele-perception and tactile sensation to track the rehabilitation process, collecting signals related to approaching speed and grip strength sequentially. The SAER uses polyurethane ionoelastomer incorporated with quasi-solid conductive salt as the electric field receptor, and is integrated on a rehabilitation-training ball after assembly to establish an untethered detection device; this enables the remote capture of hand approaching parameter within a 9 cm range, followed by the quantification of grip strength when contacting and grasping. Furthermore, a data-driven assessment system is established by integrating machine learning, which accurately classifies rehabilitation efficiency into six levels; it supports for rehabilitation evaluation and training programs adjustment. Overall, the SAER-based rehabilitation management system establishes a paradigm that synergistically evaluating parameters corresponding to neuromuscular functional restoration and holds strong potential for home-based active rehabilitation for minimizing dependence on frequent clinical supervision.
Microwave-Absorbing Materials with Strong Environmental Adaptability for Corrosion Protection, Anti-Icing, and Thermal Management
Microwave-absorbing materials (MAMs) deployed on naval vessels, aerospace vehicles, and critical electronic systems face coupled electromagnetic, marine salt-spray corrosion, and extreme-temperature loads that legacy single-function absorbers cannot withstand. This review consolidates progress on three environmentally adaptive MAM classes: corrosion-protective, anti-icing, and thermal-management absorbers. The electromagnetic loss and impedance-matching fundamentals are first established, then the synergistic mechanisms, design strategies, and characterization protocols for each class are examined against representative material systems and their measured performance. The analysis identifies a shared design logic—multiscale hierarchical architecture, interfacial polarization engineering, and multifunctional phase integration—while distinguishing the divergent protection mechanisms: barrier and passivation effects for corrosion, surface-energy and latent-heat regulation for anti-icing, and phonon–electron transport decoupling for thermal management. Persistent bottlenecks include the trade-off between impedance matching and protective-layer density, the absence of standardized coupled-field test protocols, and the scarcity of long-term salt-spray and thermal-cycling durability data. Future directions are delineated: intelligent self-adaptive absorbers, multiphysics-coupled simulation frameworks, and environmentally benign multifunctional integration. The review provides a theoretical and technical basis for the design, construction, and engineering scale-up of next-generation high-performance absorbers for aerospace, electronic, and marine equipment.