An excellent deep-ultraviolet birefringent material based on [BO2]∞ infinite chains

Abstract

Birefringent materials play indispensable roles in modulating the polarization of light and are vital in the laser science and technology. Currently, the design of birefringent materials operating in the deep-ultraviolet region (DUV, λ ≤200 nm) is still a great challenge. In this work, we developed a new DUV birefringent crystal LiBO2 based on [BO2]∞ infinite chains in the Li-B-O system, which simultaneously achieves the shortest UV cutoff edge (164 nm) and the largest birefringence (≥0.168 at 266 nm) among all the reported borate-based DUV birefringent materials. Single crystals of LiBO2 with dimensions up to Ø55 × 34 mm3 were grown by the Czochralski method, providing access to large-sized single crystal with low cost. Moreover, it has a high laser damage threshold and stable physicochemical properties. These outstanding characters unambiguously support that LiBO2 can be an excellent birefringent material for DUV application.

CaB2O2F4: A Novel [BOF2]∞-Based Structural Template with a Strong Second Harmonic Generation Response and Large Band Gap

“…, the hyperpolarizability of the micro-group has a crucial impact on the second harmonic generation (SHG) response of a crystal. − Based on our previous research, the structures with high-polymerized functional modules exhibit enhanced optical performances, e.g. , Li 2 BO 2 F and CaBO 2 F with [BO 2 ] ∞ -chain. − In fluorooxoborates, the [BO 2 F 2 ] unit has the relatively large hyperpolarizability among [BO x F 4– x ] ( x +1)– ( x = 1, 2, 3), [BO 4 ] and [BO 3 ] groups, so the fluorooxoborate composed of single [BO 2 F 2 ] unit will take on strong SHG response. Reviewing fluorooxoborates only composed of the [BO 2 F 2 ] unit, our group reported A 3 B 3 O 3 F 6 series (A = Na, K, Rb, and Cs) and BaBOF 3 with three experimentally available phases, i.e.…”

Na3YB8O15: a new rare-earth borate with an infinite one-dimensional [B8O15]∞chain and a short ultraviolet cutoff edge

“…1–9 The diversity of the structure and properties of borate originates from the fact that, on the one hand, B atoms can coordinate with two, three, or four O atoms to form linear BO 2 , planar BO 3 , and tetrahedral BO 4 units. 10–15 The formed FBBs can further be connected to form 1D chains, two-dimensional (2D) layers, or three-dimensional (3D) networks by corner- or edge-sharing. 16–21 On the other hand, by combining the B–O units or frameworks with various metal cations, the diversity of the structure and properties can be further increased.…”

BaB2P2O8F2: A Fluoroborophosphate with [B2P2O8F2]∞ Layers and Deep-Ultraviolet Cutoff Edge

“…Recently, the exploration of new deep-ultraviolet (DUV) optical crystals has attracted widespread attention and interest in order to meet the development of DUV laser technology, and borates have attracted extensive attention because of their diversity in structural chemistry, excellent performance, and extensive application. − As a branch of borates, borophosphates feature diverse anionic structures constructed from [BO 3 ], [BO 4 ], and [PO 4 ] groups through various linkage types, and the structural diversity of borophosphates provides great motivation for the exploration of new functional materials. − In the systematic studies of borophosphate crystal structures by Kniep et al, , a series of borophosphates having nonlinear-optical (NLO) properties, such as Na 5 B 2 P 3 O 13 , BPO 4 , MBPO 5 (M = Ba, Sr), and Ba 3 (ZnB 5 O 10 )PO 4 , as well as birefringent properties, such as K 2 MB 4 PO 10 (M = K, Rb, Cs), and NH 4 (B 6 PO 10 (OH) 4 )·H 2 O, have been reported. In recent years, the “fluorination strategy” was proposed to optimize the structure and properties of borate compounds by introducing F atoms into the borate anionic groups. − This strategy was also applicable to the borophosphate system. − When the O atom on the [BO 4 ] and [PO 4 ] groups was replaced with the F atom, the oxyfluoride groups [BO x F 4– x ] ( x = 1–3) and [PO x F 4– x ] ( x = 1 and 2) were formed. − The oxyfluoride groups combine with the [BO 3 ], [BO ...…”