Possible liquid-liquid transition of gallium confined in opal

We have performed nuclear magnetic resonance (NMR) measurements on gallium confined in opal. In a cooling process, between 260 and 2200.3em0exK, the NMR spectra of gallium in opal exhibit two separate peaks at ~122.5790.2em0ex48 (low frequency, LF) and ~122.5810.2em0ex890.3em0exMHz (high frequency, HF). These two peaks can be interpreted as the existence of two liquid gallium phases in opal. These two liquid phases of gallium have different freezing points with a transition temperature near 2600.3em0exK. The intensity of the LF signal decreases with the increase in intensity of the HF signals. The rapid changes of the Knight shift are at ~2400.3em0exK for the LF signal and at ~1830.3em0exK for the HF signal. The relaxation time T₁ of the NMR signals for Ga⁷¹ rapidly changes at ~2400.3em0exK for the LF signal and at ~1830.3em0exK for the HF signal, which suggests that these two kinds of liquid gallium have different freezing temperatures, ~240 and ~1830.3em0exK for the HF and LF phase, respectively.