Figure 4. Raman spectra of (a) VO₂(B), (b) VO₂(A), (c) VO₂(M1) and VO₂(R) grown on LAO substrates. The spectra were recorded at room temperature except the VO₂(R) phase shown in (c), which was obtained by heating the M1 phase sample to 100 °C in air.