Research for Ferroelectricity of Substances including Tetramethylammonium Radical in the Ammonium Sulfate Family.

点击翻译按钮获取中文摘要

The ferroelectrics in the ammonium sulfate [( <NH_4> ) <_2> <SO_4> ] family substances including tetramethylammonium [N( <CH_3> ) <_4> ] radical, such as [N( <CH_3> ) <_4> ] <_2> Zn <Cl_4> , [N( <CH_3> ) <_4> ] <_2> Co <Cl_4> ,[N( <CH_3> ) <_4> ] <_2> Cu <Br_4> , etc., are known. On the other hand, ABX <Y_4> -type ferroelectrics like RbLi <SO_4> and <NH_4> Li <SO_4> have been reproted. Therefore, single crystals of [N( <CH_3> ) <_4> ] <_2> X <Y_4> - and N( <CH_3> ) <_4> BX <Y_4> - (B:monovalent cation, X <Y_4> : <SO_4> , Zn <Cl_4> , etc.) type materials were prepared and their physical properties were measured from the view point of investigation of ferroelectricity in these substances.First, we reported the dielectric properties and the features of thermal anomaly and thermal dilatation of ferroelectric [N( <CH_3> ) <_4> ] <_2> Zn <Cl_4> and [N( <CH_3> ) <_4> ] <_2> Co <Cl_4> in detail.Two kinds of crystals were obtained from the aqueous solution of chemical formula N( <CH_3> ) <_4> H … More <SO_4> . It was found that one of them grown at about 40 ゜C is N( <CH_3> ) <_4> H <SO_4> ・ <H_2> O and the other grown at about 90 ゜C is intermediate material between N( <CH_3> ) <_4> H <SO_4> and N( <CH_3> ) <_4> H <SO_4> ・ <H_2> O. It was also found that the former shows ferroelectricity in a temperature range between -104 ゜C and about 40 ゜C. We cannot prepare perfect crystals of N( <CH_3> ) <_4> H <SO_4> , yet.Usually, single crystals of [N( <CH_3> ) <_4> ] <_2> Ni <Cl_4> are grown by means of the evaporation method using an organic solvent. Single crystals prepared by the evaporation of aqueous solution of N( <CH_3> ) <_4> Cl : Ni <Cl_2> = 2 : 1 mixture at about 80 ゜C were found to be N( <CH_3> ) <_4> Ni <Cl_3> and to show distinct phase transitions at -106 ゜C and 160 ゜C.In this research, we tried to prepare many kinds of crystals of materials including tetramethylammonium radical in the ammonium sulfate family, and studied on the feature of their phase transitions. Hereafter, we want to carry out the study for the A B X <Y_4> -type substances in the ammonium sulfate family, especially such as RbLi <SO_4> , and to clarifiy the origins of the dielectric properties, the incommensuration, etc. of these materials. Less