Stress-induced phase and structural changes in KDP crystals
Stress-induced phase and structural changes in KDP crystals
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DOI：
10.1016/j.commatsci.2015.07.044
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发表时间：
2015-11
影响因子：
3.3
通讯作者：
K. Mylvaganam;Liangchi Zhang;Y. Zhang
中科院分区：
文献类型：
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作者：
K. Mylvaganam;Liangchi Zhang;Y. Zhang
磷酸二氢钾（KDP）是一种非线性光学材料，广泛应用于光调制器和频率转换器。然而，在制造光学KDP组件时，制造过程中的机械应力通常会带来意想不到的表面完整性问题，例如相变和裂纹。本文探讨了一些可能的相变单晶四晶KDP在单轴，双轴和三轴压/拉应力外施加通过使用从头算密度泛函理论（DFT）计算。它表明，晶体对称性/相变的变化是由于氢动力学。在沿着该方向的1.4GPa的单轴拉伸应力作用下< 1 1 0>，具有I42 d（D2 d12）空间群的四方晶系结构的顺电相II将发生向正交（C2 v）结构的不可逆转变.
Potassium dihydrogen phosphate (KDP) is a nonlinear optical material which has been widely used in optical modulators and frequency converters. In making optical KDP components, however, the mechanical stresses in a manufacturing process often bring about unexpected surface integrity problems such as phase changes and cracks. This paper explores some possible phase transformations in monocrystalline tetragonal KDP under uniaxial, biaxial and triaxial compressive/tensile stresses externally applied through the use of ab initio Density Functional Theory (DFT) calculations. It shows that the change in crystal symmetry/phase transitions is due to hydrogen dynamics. Under a uniaxial tensile stress of∼ 4 GPa along the< 1 1 0> direction, the paraelectric phase II, which has a tetragonal structure belonging to the I42d (D 2 d 12) space group, will undergo an irreversible transformation to an orthorhombic (C 2v) structure.