Communication Cite This: Inorg. Chem. 2019, 58, 8918−8921
pubs.acs.org/IC
KNa4B2P3O13: A Deep-Ultraviolet Transparent Borophosphate Exhibiting Second-Harmonic Generation Response Yi Yang,†,§ Pifu Gong,*,† Qian Huang,‡ Gaomin Song,†,§ Xiaomeng Liu,†,§ and Zheshuai Lin*,†,§ †
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Beijing Center for Crystal R&D, Key Lab of Functional Crystals and Laser Technology of Chinese Academy of Sciences, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P.R. China ‡ Institute of Engineering Thermophysics, Chinese Academy of Science, Beijing 100190, P.R. China § University of the Chinese Academy of Sciences, Beijing 100049, P.R. China S Supporting Information *
frameworks owing to the diverse connection between the [BO3], [BO4], and [PO4] units. For the excellent DUVtransparency and NLO-active capabilities of [BO3], [BO4], and [PO4] genes, many borophosphates exhibit great potential for DUV NLO applications. For example, the well-known crystal BPO4 possesses a large SHG response about twice of KDP and exhibits a short DUV cutoff edge about 130 nm, both of which strongly motivated the explorations of borophosphate NLO materials. Thereafter, great efforts have been made in this field and dozens of noncentrosymmetric borophosphates have been discovered, e.g., Na 3 Cd 3 B(PO 4 ) 4 , 28 KPbBP 2 O 8 , 29 and RbPbBP2O8.30 These materials possess strong SHG response, as large as KDP, but the introduction of the heavy metal Cd/ Pb atoms results in the red shift of the cutoff edges, which deteriorates the DUV transmission. Usually, the introduction of alkali metal/alkaline-earth metal atoms into the borophosphate facilitates the promotion of ultraviolet transparency because there is no d−d or f−f electronic transition in the ultraviolet visible spectrum region. To maintain the instinct good optical properties of the [BO3], [BO4], and [PO4] genes and realize the DUV transmission, we carried out material exploration by combining the alkali/alkaline-earth metal atoms and the borophosphate units. In this work, a new alkali metal borophosphate KNa4B2P3O13 with one-dimensional structure is synthesized by the high-temperature flux method. This compound consists of 1D [B2P3O13] chains constituted by two [BO4] groups and three [PO4] groups. Thermal measurement, UV−vis−IR diffuse reflectance spectrum, and powder SHG experiments are carried out to characterize KNa4B2P3O13. Moreover, the mechanism of optical properties was investigated by ab initio methods. The single crystals of KNa4B2P3O13 were obtained by the high-temperature flux method. The single-crystal XRD data were collected to solve the crystal structure, and the powder XRD patterns were measured, which agreed well with the calculated ones and verified the validity of the solved structure (detailed information shown in Table S1). The TG-DTA curves shown in Figure S2 reveal only one endothermic peak around 736 °C with no clear weight loss among the whole
ABSTRACT: A new deep-ultraviolet transparent alkali metal borophosphate KNa4B2P3O13 is synthesized by high-temperature flux method, and its properties were characterized by a combination of experimental and ab initio methods. This compound crystallizes in the noncentrosymmetric Pna21 space group and its framework is formed of one-dimensional infinite [B2P3O13]∞ chains consisting of apex-sharing [BO4] and [PO4] tetrahedra. KNa4B2P3O13 had a short ultraviolet edge (
