Becker Jacob, Hald Peter, Bremholm Martin, Pedersen Jan S, Chevallier Jacques, Iversen Steen B, Iversen Bo B
Department of Chemistry and Interdisciplinary Nanoscience Center, University of Aarhus, DK-8000 Aarhus, Denmark.
ACS Nano. 2008 May;2(5):1058-68. doi: 10.1021/nn7002426.
Nanocrystalline ZrO(2) samples with narrow size distributions and mean particle sizes below 10 nm have been synthesized in a continuous flow reactor in near and supercritical water as well as supercritical isopropyl alcohol using a wide range of temperatures, pressures, concentrations and precursors. The samples were comprehensively characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS), and the influence of the synthesis parameters on the particle size, particle size distribution, shape, aggregation and crystallinity was studied. On the basis of the choice of synthesis parameters either monoclinic or tetragonal zirconia phases can be obtained. The results suggest a critical particle size of 5-6 nm for nanocrystalline monoclinic ZrO(2) under the present conditions, which is smaller than estimates reported in the literature. Thus, very small monoclinic ZrO(2) particles can be obtained using a continuous flow reactor. This is an important result with respect to improvement of the catalytic properties of nanocrystalline ZrO(2).
在连续流动反应器中，于近临界水、超临界水以及超临界异丙醇中，使用多种温度、压力、浓度和前驱体，合成了尺寸分布窄且平均粒径低于10 nm的纳米晶ZrO₂样品。通过粉末X射线衍射（PXRD）、透射电子显微镜（TEM）和小角X射线散射（SAXS）对样品进行了全面表征，并研究了合成参数对粒径、粒径分布、形状、聚集和结晶度的影响。根据合成参数的选择，可以获得单斜相或四方相氧化锆。结果表明，在当前条件下，纳米晶单斜ZrO₂的临界粒径为5 - 6 nm，这比文献报道的估计值要小。因此，使用连续流动反应器可以获得非常小的单斜ZrO₂颗粒。这对于改善纳米晶ZrO₂的催化性能而言是一个重要结果。
