Relationship of spectral characteristics and crystal morphology of h-WO3 nanoplates

Nanocrystals of h-WO
₃
(P
₆
/mmm, PDF 33-1387) with uncommon morphology of nanoplates with ~10 nm thickness and up to 200 nm in diameter have been precipitated with nitric acid from aqua ammonium tungstate solution. The h - β phase transition occurs at T= 385°C as it have been established with DTA and XRD measurements. IR and Raman spectra have been recorded for precipitated and calcined phases. These crystals show some specific features explained as an effect of uncommon micromorphology and nanosize range geometry.