Na0.5K0.5NbO3是一种不含铅的新型压电材料。理解该物质在高压下的晶体结构变化, 有助于深入认识并提高其材料的稳定性及压电性能。然而目前关于该物质在高压下的相结构演化过程还缺少实验研究。本工作采用基于金刚石对顶砧(DAC)的高压拉曼光谱技术, 研究了Na0.5K0.5NbO3的高压拉曼光谱特性与压致相变行为。研究发现Na0.5K0.5NbO3在高压环境下由于NbO6八面体的振动模式发生改变, 会依次发生正交相到四方相和四方相到立方相的可逆相变过程, 其相变压力分别为4.0~5.5 GPa和5.5~6.4 GPa。

Na0.5K0.5NbO3 is a new type of lead-free piezoelectric material. Understanding the crystal structure change of the material under high pressure is conducive to improving the performance and stability of a series of potassium sodium niobate-based piezoelectric materials. However, there is still a lack of experimental research on the phase structure evolution of this material under high pressure. In this study, the high-pressure Raman spectroscopy technology based on diamond anvil cell (DAC) was used to study the high-pressure Raman spectroscopy characteristics and pressure-induced phase transition behavior of Na0.5K0.5NbO3. It is found that the reversible phase transition process of orthogonal phase to tetragonal phase and tetragonal phase to cubic phase will occur in turn due to the change of vibration mode of NbO6 octahedron under high pressure, and the pressures of phase transition are about 4.0-5.5 GPa and 5.5-6.4 GPa respectively.