Temperature dependence of the Raman active phonons in CaWO4, SrWO4 and BaWO4

摘要: Abstract The temperature dependence (10–300 K) of the Raman frequency shifts for three different tungstates CaWO4, SrWO4 and BaWO4 are reported. lowest mode shows soft behaviour in calcium compound negligible change other two. remaining external modes internal behave quite normally, that is to say, small dω d T (typically −2 cm −1 K .) larger dωdT 10 ) modes. By using av pressure data we calculate pure volume contributions changes find compounds don't like normal molecular crystals. We surmise instability with respect a phase causes abnormality.