金属元素掺杂KDP晶体的第一性原理研究

First-principles Study of KDP Crystal Doped with Metal Elements

磷酸二氢钾(KDP)晶体是一种性能优良的光学材料,在非线性光学领域有着重要应用.金属杂质是影响KDP晶体生长和光学质量的重要因素.采用第一性原理计算的方法,从微观角度对Ca,Cu,Mg,Fe等金属元素在KDP晶体中的掺杂机理进行了研究,对缺陷形成能、晶体结构、化学键类型进行了分析.结果表明:4种元素掺杂缺陷的形成由易到难分别为Fe,Ca,Cu,Mg;与其他元素相比,Fe更容易进入KDP晶体中,且对晶体结构的影响较大;Fe,Cu与KDP晶体中O原子之间形成的化学键共价性更强,而Ca,Mg与O之间更偏向于形成离子键.掺杂原子能否与周围的O原子紧密结合,将会影响它们在KDP晶体中掺杂的稳定性.

Potassium dihydrogen phosphate(KDP)crystal is a kind of excellent optical material,which has important applications in the field of nonlinear optics.The existence of metal impurities is an important factor affecting the growth and optical quality of KDP crystal.In this paper,first-principles calculations were used to study the doping mechanisms of Ca,Cu,Mg and Fe in KDP crystals from a microscopic perspective,and the defect forming energies,crystal structures and chemical bond types were analyzed.The results show that the four element-doped defects formed from easy to difficult is Fe,Ca,Cu,Mg,respectively.Compared with other elements,Fe is easier to be doped into KDP crystal and has a great influence on the crystal structure.The chemical bonds formed between Fe,Cu and O atoms in KDP crystals have more covalent components,while Ca,Mg and O atoms are more inclined to form ionic bonds.In addition,whether doping atoms can be tightly bound to O atoms around them will affect their stabilities in KDP crystals.