## 2 Results and Discussion
In the Sc\({}_{2}\)O\({}_{3}\)\(\rightarrow\) YScO\({}_{3}\)\(\rightarrow\) Y\({}_{2}\)O\({}_{3}\) series, we observed \"mass effect\" when vibrational modes are shifted to the range of lower frequencies with increasing cation mass. The spectral lines of yttrium scandate are broadened due to the presentence of both Y\({}^{3+}\) and Sc\({}^{3+}\) cations in statistically equal structural positions. Due to partial overlap, a number of experimental lines are lower than predicted with factor-group analysis. Table 2 shows identification of the Raman-active modes [28]. Time-resolved luminescence excitation spectra of Nd\({}^{3+}\):YScO\({}_{3}\) have been obtained for \({}^{4}I_{9/2}\)\(\rightarrow\)\({}^{4}F_{5/2}\)\(+\)\({}^{2}H_{9/2}\) electro-dipole transitions in the Nd\({}^{3+}\) ion at selective detection of 896 nm (\({}^{4}F_{3/2}\)\(\rightarrow\)\({}^{4}F_{9/2}\) transition) at a temperature of 77 K (Figure 2a). Two intensive peaks are observed at 821.4 and 823.8 nm. The ratio of line intensities depends on delay in registration. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Assignments**[28] & **Sc\({}_{2}\)O\({}_{3}\), exp.**[28] & **Sc\({}_{2}\)O\({}_{3}\), calc.**[28] & **Sc\({}_{2}\)O\({}_{3}\)** & **YScO\({}_{3}\)** & **Y\({}_{2}\)O\({}_{3}\), exp.**[28] & **Y\({}_{2}\)O\({}_{3}\), calc.**[28] & **Y\({}_{2}\)O\({}_{3}\)** \\ \hline \multirow{4}{*}{\(A_{g}\)} & 221 & 220 & 220 & 180 & 162 & 162 & 161 \\  & 391 & 351 & 358 & - & - & 306 & 318 \\  & 495 & 498 & 494 & - & 431 & 460 & 467 \\  & 623 & 593 & - & 590 & - & 553 & 542 \\ \hline \multirow{4}{*}{\(E_{g}\)} & 273 & 273 & 273 & - & 194 & 198 & 194 \\  & 359 & 332 & - & - & 325 & 290 & 288 \\  & 430 & 416 & 429 & 400 & - & 366 & 358 \\  & 626 & 590 & - & - & - & 555 & 567 \\ \hline \multirow{4}{*}{\(F_{g}\)} & 189 & 192 & 189 & 140 & 129 & 132 & 129 \\  & 202 & 199 & - & 180 & 138 & 138 & 152 \\  & 252 & 250 & 253 & - & 182 & 181 & 207 \\  & 319 & 306 & - & - & 235 & 234 & 217 \\  & 329 & 311 & 319 & - & - & 244 & 250 \\  & 359 & 341 & 358 & - & 325 & 288 & 288 \\  & - & 368 & - & - & - & 299 & - \\  & 391 & 386 & 390 & - & - & 338 & 327 \\  & 419 & 412 & 418 & 400 & 377 & 368 & 377 \\  & - & 472 & - & 460 & - & 416 & 429 \\  & - & 491 & 494 & - & - & 442 & 467 \\  & 523 & 536 & 522 & 495 & 469 & 495 & 499 \\  & 587 & 605 & 624 & 590 & - & 545 & 514 \\  & 669 & 646 & 670 & 630 & 592 & 581 & 592 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Raman-active modes in spectra of Y\({}_{2}\)O\({}_{3}\), Sc\({}_{2}\)O\({}_{3}\) and YScO\({}_{3}\); exp.—experimental, calc.—calculated. Figure 2b shows the luminescence emission spectra of Nd\({}^{3+}\) ions being measured in the \({}^{4}F_{3/2}\rightarrow{}^{4}I_{9/2}\) electron transitions at 77 K. Nd\({}^{3+}\) ions have been excited at 823.6 and 821.4 nm, which corresponds to a maximum of peaks being observed in luminescence excitation spectra. Analysis of the spectra allows us to distinguish two independent optical centers of Nd\({}^{3+}\) ions. The luminescence kinetics have been recorded on the \({}^{3}F_{3/2}\rightarrow{}^{4}I_{9/2}\) electron transition at two different excitation wavelengths (823.6 and 821.4 nm). In both cases, decay curves are described by exponential law with lifetimes of \(\tau_{1}\)(77 K) = 290 \(\upmu\)s (at 823.6 nm excitation) and \(\tau_{2}\)(77 K) = 250 \(\upmu\)s (at 821.4 nm excitation). The close lifetimes and relatively equal intensities of the spectral lines obtained from two different centers indicate the same \(C_{2}\) symmetry in both cases. As is known [29], electro-dipole transitions are forbidden for rare-earth ion occupied centro-symmetric positions, in particular, the \(C_{3i}\) position in the bixbyite structure. The luminescence for these centers must be non-active. We assume that both of the centers have local symmetry of \(C_{2}\).