硫酸氢铵高压下相变研究

由于铁电材料在科学研究领域的重要应用,功能铁电材料的设计和机理研究一直是国内外的研究热点。材料的性能离不开结构研究,为了更好的认识和理解一种典型铁电材料-硫酸氢铵的结构和相行为,研究了17GPa压强下硫酸氢铵的高压拉曼光谱。在压力作用下,绝大多数的拉曼谱线向高波数方向移动,并且有两个特征拉曼谱带的强度发生很大的变化(1 018和3 183cm~(-1)),表明硫酸盐与铵离子正四面体的电子云密度发生重构。根据频移-压强曲线关系,得出了硫酸氢铵在6和10.5GPa附近分别存在一阶相变。根据高压下S=O伸缩振动谱带的变化规律,发现了不同相区间氢键的相反作用规律。为AHSO_4系列铁电材料压力作用下结构变化规律提供一定的研究基础。

Pressure-Induced Phase Transition of NH4HSO4

Due to the important applications of ferroelectr ic materials in the field of scientific research,the design and mechanism of fu nctional ferroelectric materials have received great attention.The properties o f materials cannot be separated from the study of structures.In order to unders tand the structure and phase behavior of a typical ferroelectric material-NH4HSO4,the in-situ high Pressure Raman measurement of NH4HSO4 up to 17 GPa is performed.With the increase of pressure,most of Raman bands shifted to hig her wave number region.And the Intensities of two Raman bands (located at 1 018and 3 183 cm-1) changed greatly with pressure,suggests that the electron density of sulfate and ammonium ion is redistributed.Based on the relationship between the frequency shift and pressure curves,it is found that there are two first-order phase transitions at about 6 GPa and 10.5 GPa,respectively.Acco rding to the changes tendency of SO stretching vibratio n band under compression,it is found that the hydrogen bond at different phases has the opposite change tendency.It provides a new strategy for investigation of AHSO4 ferroelectric materials under pressure.