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Figure 69. X-ray diffraction profiles of NdAlO3 (a) and NdAl3O6 (b and c) systems calcined at 800, 1000, 1200 and 1400 °C. Reprinted with permission from [265], S. Mathur et al., Chem. Mater. 14, 568 (2002). © 2002, American Chemical Society.

[NdAl3(OPr')12(Pr'*OH)], containing single, isolated Nd ions surrounded by optically silent metal atoms, were used as precursors. The validity of this hypothesis was verified by investigation of the optical properties of (i) monophasic NdAlO3 and (ii) NdAlO3 nanocrystals evenly dispersed in alumina matrix (NdAlO3/Al2O3).

The precursors, [NdAl(OPr')6(Pr'OH)]2 (NA) and [NdAlr (OPr'*)12(Pr'*OH)] (NA3), possess the Nd:Al ratio required for the formation of NdAlO3 and NdAlO3/Al2O3 (Fig. 68). The molecular frameworks in NA and NA3 formed by the bidentate chelation of tetrahedral isopropoxo aluminate group (s) [297] fulfill the condition of preformed Nd-O-Al bonds.

Both compounds, when subject to controlled hydrolysis, produce homogeneous xerogels that can be calcined to obtain mono- and biphasic nanomaterials (Eqs. (25)-(26)).

[NdAl(OPr')6(Pr'OH)]2 NdAlO3 (25) [NdAl3(OPr')12(Pr'*OH)] NdAlO3/Al2O3 (26)

The XRD patterns of the calcined powder obtained from NA show neodymium aluminate to be the only crystalline

Figure 68. Molecular structures of the NA and NA3 systems. Reprinted with permission from [265], S. Mathur et al., Chem. Mater. 14, 568 (2002). © 2002, American Chemical Society.
Figure 70. TEM images of (a) NdAlO3 and (b) NdAlO3/Al2O3 calcined at 1000 and 1200 °C, respectively. Reprinted with permission from [265], S. Mathur, et al., Chem. Mater. 14, 568 (2002). © 2002, American Chemical Society.

1400°C

NdAlO

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