In-situ observation of the boson peak, ωBP, of as-quenched and annealed glassy Ba2TiGe2O8 (BTG) and Ba2TiSi2O8 (BTS) was performed during a heating process. Although annealed glassy BTG and BTS indicated a monotonous decrease in ωBP with temperature, the as-quenched varieties, which Included internal stress, revealed anomalous boson behavior at ∼600°C, lower than each one's glass-transition temperature. It was suggested that the ωBP anomaly was caused by β-relaxation. This experimental result also supports the inhomogeneous structure (or cluster) model of glass.
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