Structural transformations in N-isopropylcarbazole crystal monitored by pressure-induced luminescence

✍ Scribed by J. Kalinowski; Z. Dreger; J. Godlewski; P. Mondalski

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 691 KB
• Volume: 172
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(90)80150-c

✦ Synopsis

The phase diagram for solid-solid transitions in a N-isopropylcarbazole single crystal is determined by monitoring pressure induced luminescence (PIL) pulses appearing at transition points. The structural transitions at room temperature which occur under hydrostatic pressure 0.6 and 0.46 GPa are suggested to be equivalent to previously observed normal pressure transitions at = 137 and = 200 IL. The results have been verified by calorimetric studies. The transition parameters and, in particular, transition enthalpies, are found to be strongly dependent on crystal history (thermal and pressure treatment before measurements). The tiect is assigned to local strain relaxations. The pressure-induced phase transition at 0.6 GPa has heen found to appear as a discontinuity in the pressure dependence of the maximum position of the photoluminescence spectrum and luminescence et% ciency of the crystal.