In chemical synthesis and design, the diversity of potential structures is the basis for exploring new compounds and functional materials, but it is a huge challenge for functional materials with targeted properties. However, with the development of technology, The computing power of high-performance clusters has been greatly improved. This has led to the screening of high-performance functional materials from a large database—high-throughput screening, searching for the lowest structure of the whole situation from the first principle—crystal structure prediction, It is possible to create new structures and other new methods of exploring materials by learning the existing structural features. The Pan Shilie team of the new photovoltaic functional materials laboratory of the Xinjiang Institute of Physics and Chemistry, Chinese Academy of Sciences has been conducting material software development since 2011, material design, 1. One-principles calculation and prediction studies provide direction for new material preparation.
In recent years, the research team has made some progress in crystal structure prediction and rational design of functional materials. Researchers first introduced the global energy minimum structure search method to realize the structural prediction of infrared nonlinear optical materials and ultraviolet nonlinear optical materials. In infrared nonlinear optical materials, it is the key to improve the laser damage threshold under the premise of meeting the requirements of optical applications. Researchers first introduced the global energy minimum structure search method to search for the infrared nonlinearity with excellent performance in the Na-Ga-S system. Optical material. Structure shows that NaGaS of the I-42d space group 2Not only with the commercial material AgGaS 2It has a relatively high nonlinear optical coefficient and has the highest thermal conductivity in infrared nonlinear optical materials, thus contributing to high laser damage thresholds. Therefore, NaGaS 2The laser damage threshold is effectively increased and the thermal effects due to two-photon absorption are avoided. The above results have been published in the Journal of the American Chemical Society, Inorganic Chemistry (Inorg. Chem. 2018, DOI: 10.1021/acs.inorgchem. 8b01174). In UV nonlinear optical materials, designing to meet the requirements of deep ultraviolet nonlinear optical materials and outputting coherent deep ultraviolet light is a challenging subject. Researchers search for stable structures under normal pressure in the Na-Be-BO system. Among the four phases with the lowest potential energy, the Na-6BO of the P-6 phase 3Excellent nonlinear optical properties. Deep UV cutoff side up to 171nm, frequency doubling effect and commercial standard KDP (KH 2PO 4), and the phase matching can reach the deep ultraviolet region; the above results were published in the Science Report (Sci. Rep. 2016, 6, 34839). Further, the team increased the band gap blue shift UV cutoff by introducing fluorine. On the other hand, the asymmetric distribution of electrons is beneficial to the improvement of nonlinear optical performance. The rich structure is beneficial to increase the probability of discovery of non-cardiac compounds. Based on the above characteristics, in the Be-BOF system, excellent performance is found under normal pressure. UV nonlinear optical material γ-Be 2BO 3F, its deep UV cutoff edge is as low as 138nm, the frequency doubling effect is 1.8 times KDP, and the deep ultraviolet phase matching wavelength reaches 152nm, which becomes a nonlinear optical crystal with potential application in the deep ultraviolet region. Related results were published in the Journal of the American Chemical Society. Inorganic Chemistry (Inorg. Chem. 2018, 57, 5716).
Recently, the team made breakthroughs in rational design and expanded the new material prediction method. This method is to study the structural performance relationship and explore the functional modules that control the relevant performance response, and then carry out the module design and assembly prediction new materials. Element is the basic building block for designing deep-UV nonlinear optical materials, but due to the uncertainty of frequency-doubling response and optical anisotropy response, material scientists have not paid much attention to its application in deep-UV nonlinear optical materials. In order to explore the optical anisotropic response mechanism of tetrahedrons, researchers have proposed an evaluation method for tetrahedral optical anisotropy and found that tetrahedral angle deviation caused by rare earth cations with strong covalent interactions is beneficial to tetrahedral elements. Optical anisotropy. This part of the work has been published in the journal Chemical Communications of the Royal Society of Chemistry (Chem. Commun., 2017, 53, 2818). In further research, researchers have studied tetrahedrons systematically. Prediction of optical anisotropy of compounds and finding optical isotropy for controlling tetrahedral motifs Functional module - a tetrahedral element with a 'zipper' arrangement and angular deviation. The rare earth element is used to adjust the crystal structure symmetry and optical anisotropy in phosphate without destroying the functional module. A series of deep-UV nonlinear optical materials. The birefringence of these materials is significantly improved compared to the previous non-tetrahedral compounds and has a deep UV cut-off edge. Among them, α-YSc(PO4)2 is the first case to date. Phosphorus required for preliminary evaluation of deep ultraviolet nonlinear optical materials. This pure theoretical design work was published in the international academic journal American Chemical Society (J. Am. Chem. Soc. 2018, 140, 10726).
Figure: Designing a new deep-UV nonlinear optical crystal from a central compounding functional module to a non-cardiac compound
