Raman spectra of three polytypes of lead iodide (2H, 4H and 6H) have been investigated as a function of temperature at ambient pressure. The band assignments have been carried out on the basis of folding of 2H-PbIz phonon dispersion curves in the Brillouin zone. The temperature induced changes in the Raman spectra are interpreted in terms of an interpolytypic phase transformation (at 415 K) and photodecomposition at 470 K.

Raman spectra of red and yellow forms of HgIz have been recorded as a function of temperature and pressure. Temperatures between 77 and 570 K and pressures up to 14 kbar have been used to investigate the vibrational modes of four (and possibly five) phases of this material. No evidence could be found from the Raman spectrum to support the suggestion that a thermal anomaly within the stability range of the red form indicates a 111 to IV transition. Clear differentiation between the yellow high temperature and high pressure phases has been shown, and the phase boundary ( YHp -+ YrIT) located. A previously unreported Raman spectrum of an orange phase is shown, and a modified phase diagram is presented.

Polarized Raman studies have been carried out on a single crystal of potassium azide as a function of temperature and band assignments have been made. The Raman spectrum of KN3 microcrystalline samples as a function of pressure is reported.

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