Synthesis of calcium aluminate nanoflakes and nanochains from woody biomass

• Calcium aluminate nanoflakes and nanochains are synthesized from woody biomass.
• Catalyst-free CVD is the main responsibility for the growth at 1,500 °C in H2.
• Hexagonal CaAl12O19 nanoflakes have thickness of approximately 100 nm
• Monoclinic CaAl2O4 nanochains are single crystal oriented along the (100) plane.
• CL spectra of nanoflakes and nanochains have the potential in optical applications.

Studies on the fabrication of nanoscaled calcium aluminate materials and their growth mechanisms still present key challenges. In this work, we report the catalyst-free chemical vapor deposition of calcium aluminate nanostructures including nanoflakes and nanochains during the carbonization of woody biomass at 1500 °C in H2. The mixture of Al and Al2O3 is prepared as a starting material with henequén fibers for the synthesis. Hexagonal CaAl12O19 nanoflakes and monoclinic CaAl2O4 nanochains are found as main products after the synthesis. The CaAl12O19 nanoflakes have thickness of approximately 100 nm. The CaAl2O4 nanochains exhibit a regular periodic structure that is composed of nanowires and nanobeads of 100 nm and 300 nm in diameter, respectively. The nanochains oriented along the (100) plane grow to lengths of dozens of microns. The surface of nanochains is covered by an amorphous layer with a thickness of approximately 5 nm. Cathodoluminescence measurement reveals that both CaAl12O19 nanoflakes and CaAl2O4 nanochains have the potential in optical applications.

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