Estimation of anharmonic parameters of nano-crystalline Sc2O3 and Nd2O3

We report anharmonic characteristics of cubic Scandium Oxide (Sc2O3) and hexagonal Neodymium Oxide (Nd2O3) through temperature dependent phonon mode variation in the temperature range 80-440 K. The samples were characterized as nanocrystalline and stoichiometric with crystallite sizes of 31 nm for Sc2O3 and 59 nm for Nd2O3. Under ambient conditions, Sc2O3 was found to have 10 phonon modes out of expected 22 Raman modes while Nd2O3 showed all 4 predicted phonon modes. The temperature dependent shift in wave-number of Raman modes and broadening of the phonon modes has been analysed in light of thermal and anharmonic effects. The lattice expansion and strong anharmonic interactions were observed with an increase in temperature that resulted in measurable phonon softening. However, both samples were found to have stable phases within the studied temperature range. The total anharmonicity and anharmonic parameters along with phonon lifetimes are estimated. For the most intense phonon modes of Sc2O3 and Nd2O3, the total anharmonicity is calculated as 3.44 x 10(-5) K-1 and 5+.47 x 10(-5) K-1 respectively. The estimated anharmonic constants revealed the predominance of the three phonon process for decay as a function of temperature.

Automated summary

In this study, anharmonic characteristics of cubic Scandium Oxide and hexagonal Neodymium Oxide were investigated through temperature dependent phonon mode variation. The results revealed lattice expansion and strong anharmonic interactions with temperature increase, leading to measurable phonon softening. Both samples exhibited stable phases within the studied temperature range.