Au(Si)-filled β-Ga2O3 nanotubes as wide range high temperature nanothermometers

Au(Si)-filled $\beta \text{-}{\mathrm{Ga}}_2{\mathrm{O}}_3$ nanotubes were fabricated by an effective one-step chemical vapor deposition method. The Au(Si) interior was introduced by capillarity. Linear thermal expansion of Au(Si) with a coefficient of thermal expansion (CTE) as high as $1.5\times {10}^{-4}(1∕K)$ within single crystal ${\mathrm{Ga}}_2{\mathrm{O}}_3$ shell up to ${800}^{°}\mathrm{C}$ was observed by in situ transmission electron microscopy. The high CTE is correlated to partial melting of Au(Si). As ${\mathrm{Ga}}_2{\mathrm{O}}_3$ possesses excellent thermal and chemical stability, the structure can be used as a wide range high-temperature nanothermometer within localized regions of nanosystems.