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Nano Research

Article Title

Controllable synthesis of elongated hexagonal bipyramid shaped La(OH)3 nanorods and the distribution of electric property by off-axis electron holography

Keywords

controllable synthesis, elongated hexagonalbipyramid, lanthanum hydroxide, electric property, electron holography, microwave absorption

Abstract

Rare earth oxides/hydroxides are important emerging materials owing to theirunique properties. Shape-controlled synthesis of elongated hexagonal bipyramidshaped La(OH)3 nanorods with different aspect ratios and trigram-shapedLaCO3OH nanosheets was systematically carried out by controlling the reactionconditions. Hydrazine and polyvinylpyrrolidone (PVP) surfactants used insynthesis are assumed to play a key “dual-template” role in determining theaspect ratio and shape of the resulting nanostructures. Elongated hexagonalbipyramid shaped La(OH)3 nanorods were found to grow along the preferredorientation [0001]. Six equivalent crystallographic facets, (202_0), (022_0), (22_00),(02_20), (2_200), and (2_020) lattice planes, were found to be exposed on the sidesurfaces on each nanorod as confirmed by combined transmission electronmicroscopy (TEM), high-resolution transmission electron microscopy (HRTEM),and selected area electron diffraction (SAED) analyses. A double-polarizationphenomenon was found to occur at the nanorod surfaces by employing off-axiselectron holography, implying that the material could be used as an effectivedielectric microwave absorber. La(OH)3 nanorods with larger aspect ratiosexhibit better absorption properties with respect to the maximum reflection lossand effective absorbing bandwidth. Thus, a novel method towards the reasonabledesign of bipyramid shaped La(OH)3 nanorods exhibiting tunable microwaveabsorption properties is proposed based on our synthesis strategy.

Graphical Abstract

Publisher

Tsinghua University Press

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