Question

What temperature ebba is crystalline solid?

Answer 1

Melting and crystallization processes of EBBA (N-p-ethoxybenzylidene-p'-butyl aniline) have been studied by the method of microscopic observation. A solid sample obtained by rapid cooling (cooling rate: 40 K/min) from nematic to 5°C (sample A) shows granular texture. A band like crystal grows in sample A at room temperature. A solid sample obtained by quenching (cooling rate: 13 K/s) from nematic to about - 100°C (sample B) shows cloudy texture. In the heating process sample B transforms to a more stable crystalline form which shows mosaic texture. A needle crystal grows slowly in a supercooled nematic state, then smaller needle crystals grow rapidly around the needle crystal. The formation and transformation processes of solid modifications are explained on the basis of the idea of instability of them, and schematic phase diagram of those solid forms is presented.

Keywords: EBBA, liquid crystals, nematic, solids, crystal growth, microscopic observation

Answer 2

Crystalline solids are anisotropic in nature, that is, some of their physical properties like electrical resistance or refractive index show different values when measured along different directions in the same crystals. This arises from different arrangement of particles in different directions.