Structural and Optical Properties of NdAlO3 Nanocrystals Embedded in an Al2O3 Matrix

Abstract

Fabrication of an oxide−oxide nanocomposite, containing a homogeneous dispersion of NdAlO3 nanocrystals in an Al2O3 matrix, is achieved by employing a single molecular compound, [NdAl3(OPri)12(PriOH)], in the sol−gel process. X-ray diffraction patterns of the composite material show NdAlO3 to be the only crystalline phase, up to 1200 °C, with an equimolar part of amorphous Al2O3. The crystallization of alumina (δ-, γ- and κ-phases) occurs at higher temperatures (>1300 °C). TEM investigations reveal a bimodal distribution of particles where NdAlO3 crystallites are uniformly dispersed in an amorphous Al2O3 matrix. HR-TEM analysis shows a composite structure formed by NdAlO3 nanocrystals (50−60 nm) homogeneously incorporated in a matrix of smaller alumina particles (10−12 nm). The existence of two chemically different Al(III) species (Al2O3 and NdAlO3), in the composite, is proven by 27Al solid-state NMR and XPS studies. The line deconvolution of the Al 2p XPS spectrum reveals two components in a 1:2 ratio w...