An X-Ray and Microscopic Investigation of the Thermotropic Phases of Lead(II)Decanoate

Abstract

The phase textures observed on heating lead(II)decanoate, (CH₃(CH₂)₈COO)₂Pb, from the room temperature crystalline solid to isotropic liquid melt are characterised by polarising light microscopy and X-ray diffraction. The results suggest a phase sequence:

Though the phase assignments are consistent with conoscopic observations, molecular modelling and other calculations, they disagree somewhat with the assignments previously proposed by other workers. However, unlike previous work, the effects of thermal expansion. and orientational disordering in the long axes of carboxylate chains are quantified as a function of temperature, and the phase sequence assigned in the light of these considerations in conjunction with the microscopic and X-ray data.

Key Words:

• Lead(II)decanoate
• mesophase
• smectic C
• X-ray diffraction
• light microscopy