Exploration On The Dielectric Properties Of Nitrogen- Or Oxygen-containing Heterocyclic Compounds

Phase transitions often occur accompanied by the abnormal changes of physical properties such as dielectric, piezoelectric, thermaldynamic properties and so on. Generally speaking, the ferroelectric materials display ferroelectric-paraelectric phase transitions and thus apply in the communications, information storages, infrared sensors and piezoelectric sensors, etc. Given all this, fourteen organic-inorganic hybrid compounds were synthesized. Subsequently, their crystal structures, dielectric and thermodynamic properties were discussed, in order to obtain the novel phase transition or ferroelectric materials. The main work is divided into three parts:Part ?:4-methylimidazole as the basic building unit reacted with the inorganic acids or the metal chlorides to obtain five compounds:C12H24O6·(C4H7N2)+·ClO-4 (1), C12H24O6·(C4H7N2)+·BF-4 (2),(C4H7N2)2+2·CuCl2-4 (3), (C4H7N2)+·MnCl-3·H2O (4), (5). And then their crystal structures were characterized. The results of the temperature-dependent dielectric constant measurements in the temperature range of-180?-150 ? indicated that these five compounds did not display any observable dielectric anomalies.Part ?:3-morpholin-4-yl-propyl-ammine as the basic building unit reacted with the inorganic acids or the metal chlorides to obtain six compounds:(C7H17O1N2)+·BF4-(6), (C7H17O1N2)+·Cl04- (7), (C7H17O1N2)+·PF6-·H2O (8), (C7H17ON2)2+·CuCl42- (9), (C7H17O1N2)2+·CoCl42-(10), (C7H17O1N2)2+·ZnCl42-(11).Among them, the DSC measurement and the crystal structure characterizations for the compound (6) initially confirmed that it exhibited a high temperature structural phase transition at about 80 ?. The results of the temperature-dependent dielectric constant measurements in the temperature range of -180?-150 ? indicated that it displayed dielectric anomalies at around 80 ?. However, no dielectric anomalies were observed in the other five compounds.Part ?:The crown ether as the basic building unit reacted with the metal chlorides to obtain three complexes:C10H20O5·BiCl3 (12), C10H20O5·SbCl3 (13), C10H20O5·SbCl6-·OH3+ (14). The DSC measurements and the crystal structure characterizations for the three complexes initially confirmed their structural phase transitions. The results of the temperature-dependent dielectric constant measurements in the temperature range of-180?-150? indicated that those structural phase transitions occurred accompanied by dielectric anomalies.