Li Quanjun, Zhang Huafang, Liu Ran, Liu Bo, Li Dongmei, Zheng Lirong, Liu Jing, Cui Tian, Liu Bingbing
State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, P.R. China.
Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
Nanoscale. 2016 Jan 28;8(4):2412-7. doi: 10.1039/c5nr07503c.
The size effects on the high pressure behaviors of monoclinic (MI) ZrO2 nanoparticles were studied using in situ high pressure synchrotron X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). A size-dependent phase transition behavior under high pressure was found in nanoscale ZrO2. The normal phase transition sequence of MI-orthorhombic I (OI)-orthorhombic II (OII) occurs in 100-300 nm ZrO2 nanoparticles, while only the transition of MI-OI exists in ultrafine ∼5 nm ZrO2 nanoparticles up to the highest experimental pressure of ∼52 GPa. This indicates that the size effects preclude the transition from the OI to the OII phase in ∼5 nm nanoparticles. Upon decompression, the OII and OI phases are retained down to ambient pressure, respectively. This is the first observation of the pure OI phase ZrO2 under ambient conditions. The bulk moduli of the MI ZrO2 nanoparticles were determined to be B0 = 192 (7) GPa for the 100-300 nm nanoparticles and B0 = 218 (12) GPa for the ∼5 nm nanoparticles. We suggest that the significant high surface energy precludes the transition from the OI to the OII phase and the nanosize effects enhance the incompressibility in the ultrafine ZrO2 nanoparticles (∼5 nm). Our study indicates that this is a potential way of preparing novel nanomaterials with high pressure structures using nanosize effects.
利用原位高压同步辐射X射线衍射（XRD）和X射线吸收光谱（XAS）研究了单斜相（MI）ZrO₂纳米颗粒高压行为的尺寸效应。在纳米级ZrO₂中发现了高压下与尺寸相关的相变行为。100 - 300 nm的ZrO₂纳米颗粒中发生MI - 正交相I（OI） - 正交相II（OII）的正常相变序列，而在高达约52 GPa的最高实验压力下，在约5 nm的超细ZrO₂纳米颗粒中仅存在MI - OI的转变。这表明尺寸效应阻止了约5 nm纳米颗粒中从OI相到OII相的转变。减压后，OII相和OI相分别保留到常压。这是在环境条件下首次观察到纯OI相ZrO₂。100 - 300 nm纳米颗粒的MI ZrO₂纳米颗粒的体模量确定为B₀ = 192（7）GPa，约5 nm纳米颗粒的体模量为B₀ = 218（12）GPa。我们认为，显著的高表面能阻止了从OI相到OII相的转变，纳米尺寸效应增强了超细ZrO₂纳米颗粒（约5 nm）的不可压缩性。我们的研究表明，这是一种利用纳米尺寸效应制备具有高压结构新型纳米材料的潜在方法。
