Fig. 2

Thermal characterization of NA-Al2O3 host materials. a SEM images of NA-Al2O3. b SEM images of NA-Al2O3-1000. c XRD patterns of NA-Al2O3 and NA-Al2O3-1000. d HRTEM image of a typical nanosheet of NA-Al2O3-1000. Upper panel: It was aligned to an edge-on condition, namely, a condition that the basal surfaces (2\(\overline 2\)0) of nanosheets were in parallel with the electron beam. The inset is the FFT pattern recorded from the nanosheet. Lower panel: A schematic diagram showing the geometry of the nanosheets. The two basal planes of the nanosheet are colored blue. The scale bar in (a and b corresponds to 2 µm, and in d corresponds to 5 nm