Thermal expansion and optical length variation of sodium β-alumina along the c-axis

Thermal expansion and the optical length variation have been measured for a single crystal sodium β-alumina, along the c-axis. A laser interferometer has been used in the measurement. The measurements of the length and optical length variation do not indicate any anomalous behavior. The thermal expansion and thermooptic coefficients vary smoothly like the ionic conductivity and do not display any indication of cooperative effects.