u00b0 c in a 2 u03bcm and 6 u03bcm cell respectively a zero twist state is obtained for up to 14 u00b0 c and up to 8 u00b0 c above the s a to cholesteric phase transition temperature fig8 and 9 show the tilt angle i e half cone angle and spontaneous polarization ps as a function of temperature for cm6 this has phase temperature values isotropic 126 1 u00b0 cholesteric 84 u00b0 s a 65 u00b0 s c 5 u00b0 s the pitch temperature curve is similar to fig7 b the mixture being compensated i e infinite pitch at u02dc 119 5 u00b0 c in a 2 u03bcm cell a zero twist state is obtained for a few u00b0 c above the smectic a to cholesteric phase transition temperature this has the following phase transition temperatures isotropic 127 5 u00b0 cholesteric 92 4 u00b0 s a 72 u00b0 s c 10 u00b0 s in a 6 u03bcm cell a zero twist state is obtained for up to 3 u00b0 c above the smectic a to cholesteric phase transition temperature this has the following phase transition temperatures isotropic 147 1 u00b0 chol 101 1 u00b0 s a 85 1 u00b0 s c 13 u00b0 s the pitch temperature curve is similar to fig7 b the compensation temperature i e where the pitch is infinite occurs at u02dc 119 u00b0 c in a 2 u03bcm cell a zero twist state can be obtained just above the smectic a to cholesteric phase transition temperature isotropic 135 u00b0 cholesteric 52 3 u00b0 s c 15 u00b0 s 25 u00b0 s in a 6 u03bcm cell a 0 u00b0 twist state was obtained for up to u02dc.