Symmetry of LaAlO{sub 3} nanocrystals as a function of crystallite size

Properties of LaAlO{sub 3} nanocrystallites obtained by the precipitation method, doped with praseodymium and chromium ions were examined by spectroscopic means. Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and electronic spectroscopy proved t...

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Bibliographic Details
Published inJournal of solid state chemistry Vol. 183; no. 9
Main Authors Deren, P.J., Lemanski, K., Gagor, A., Watras, A., MaLecka, M., Zawadzki, M.
Format Journal Article
LanguageEnglish
Published United States 15.09.2010
Subjects
ALUMINATES
ALUMINIUM COMPOUNDS
ANNEALING
CHARGED PARTICLES
CHROMIUM IONS
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
DOPED MATERIALS
ELECTRON MICROSCOPY
EMISSION SPECTRA
HEAT TREATMENTS
IONS
LANTHANUM COMPOUNDS
LASER SPECTROSCOPY
MATERIALS
MICROSCOPY
MINERALS
NANOSCIENCE AND NANOTECHNOLOGY
NANOSTRUCTURES
OXYGEN COMPOUNDS
PEROVSKITES
PHASE TRANSFORMATIONS
PRASEODYMIUM IONS
PRECIPITATION
RAMAN SPECTROSCOPY
RARE EARTH COMPOUNDS
SCATTERING
SEPARATION PROCESSES
SPECTRA
SPECTROSCOPY
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TRANSMISSION ELECTRON MICROSCOPY
TRIGONAL LATTICES
X-RAY DIFFRACTION
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Summary:Properties of LaAlO{sub 3} nanocrystallites obtained by the precipitation method, doped with praseodymium and chromium ions were examined by spectroscopic means. Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and electronic spectroscopy proved that symmetry of LaAlO{sub 3} crystallites depends on their size. At room temperature the smallest obtained crystals (average size {approx}5 nm) have cubic symmetry, while the largest ones (average size over 110 nm) exhibit rhombohedral symmetry. Possible explanations for this phenomenon are discussed. - Graphical Abstract: The 77 K emission spectra of LaAlO{sub 3}:Pr{sup 3+} nanocrystallites codoped with Cr{sup 3+} as a function of the annealing temperature. Intensities were normalized to the maximum of the {sup 3}P{sub 0{yields}}{sup 3}H{sub 4} transition. The R line at 13633 cm{sup -1} vanish with decreasing the nanocrystals size and is absent for the smallest ones.
ISSN:0022-4596
1095-726X
DOI:10.1016/j.jssc.2010.07.015