RAMAN SPECTRAL SHIFT IN THE ISOMORPHOUS SERIES (ZR1-XHFX)SIO4

Approximately linear, progressive shifts in the laser Raman spectra of members of the zircon-hafnon isomorphous series are confirmed among f ive populations of synthetic (Zr1-xHfx)SiO4 crystals. Deformational be nding modes are least affected by atomic substitution. Most stretching modes show an increase of c. 0.1 cm(-1) per 0.01[Hf/Zr+Hf]. External translational and rotational motions show a lowering of frequencies wi th increasing hafnium content ranging up to 0.58 cm(-1) per 0.01[Hf/Zr +Hf] for the more cation-dependent modes. These variations specify lim its for the use of the Raman microprobe to evaluate the relative homog eneity of both individual and populations of (Zr1-xHfx)SiO4 crystals.