Probing the effect of R-cation radii on structural, vibrational, optical, and dielectric properties of rare earth (R=La, Pr, Nd) aluminates
2022; Elsevier BV; Volume: 48; Issue: 16 Linguagem: Inglês
10.1016/j.ceramint.2022.04.285
ISSN1873-3956
AutoresMinal Gupta, Omkar V. Rambadey, Pankaj R. Sagdeo,
Tópico(s)Luminescence Properties of Advanced Materials
ResumoThe present study correlates the effect of R-cation radii on structural, vibrational, optical, and dielectric properties of rhombohedral rare earth aluminates RAlO 3 (R = La, Pr, Nd). The polycrystalline samples of RAlO 3 have been synthesized using sol-gel synthesis technique. Pure rhombohedral phase of RAlO 3 samples has been confirmed with X-ray diffraction. Systematic decrements in the lattice parameter, bond length, and bond angle have been observed, giving rise to structural distortion due to decrease in ionic radii of R-cation. The phononic properties of RAlO 3 have been investigated through Raman spectroscopy, where the degree of distortion of AlO 6 octahedra can be analyzed with the peak position of E g and A 1g modes. An increase in the energy bandgap with decreasing R-cation radii shows an interconnection with the decrease in Al–O bond length. Interestingly, the decreasing dielectric constant with decreasing ionic radii of R-cation has been correlated with the difference in electronegativity of cation(R 3+ )-anion(O 2− ) pair. Also, a positive linear relationship between dielectric constant and energy bandgap has been investigated using Penn model.
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