Thermal effects in Raman spectra of hexagonal boron nitride and nanotube-containing boron nitride soot

The temperature‐induced changes in Raman spectra of two BN‐based materials: a hexagonal boron nitride and soot with single‐wall BN nanotubes, have been measured in temperature range 77–600 K in course of heating in the oven/cryostat cell. A nonlinear temperature dependence of the tangential Raman mode position (being at 1366 cm–1 at room temperature) has been observed for both materials. In the temperature range 350–600 K a linear approximation of the tangential Raman mode shifting was applicable. The measured rates were –0.014 cm–1/K (for h‐BN) and –0.027 cm–1/K (for the nanotube‐containing sample). The effects of the oven and laser heating have been compared. Under the laser heating with the same power density the nanotube‐containing soot demonstrated much bigger shifts (up to 30 cm–1) than h‐BN. The data obtained are useful for in‐situ diagnostics of different BN‐based phases in course of synthesis. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)