Structural Transitions of Silicate Nanocrystals in the Glass

G. Abdurakhmanov, G. S. Vakhidova
2012 American Journal of Materials Science  
The temperature dependences of resistivity and thermopower measurements reveal that nanocrystals of silicates in lead-silicate glass of various compositions undergo structural transitions in the temperature range of 800 -1000 K. The diameter of these nanocrystals estimated from Scherrer's formula is about 0.8 -1.6 nm and each nanocrystal consists of 8 -64 unit cells. Structure transitions are detected as sharply maxima of resistivity ρ and thermopower S at temperature T = 800 -100 K.
more » ... -100 K. Lead-silicate glass was doped by RuO 2 up to 16 weight% to facilitate the measurements of the ρ and the S. The doped lead-silicate glass has a metal-like behavior at the room temperature: the temperature dependences ρ(T) and S(T) are very slow, the value of the S is typical for metals (few and tens of μV/K). Beyond the maximum of the resistance (temperature T > 1000 K) doped lead-silicate glass turns into typical semiconductor having energy gap about 0.05 -1.5 eV depending on the composition of the glass. Anomalous thermal expansion of the RuO 2 relict crystals is detected at the temperatures of 800 -1000 K as well.
doi:10.5923/j.materials.20120201.07 fatcat:y77wvcuryrcv5f5iqtzbck2f7y