关于"消失的多态体"的研究:α-p-NCC的热和磁性表征
Yassine Beldjoudi1, Ana Arauzo2, Fernando Palacio2
1Department of Chemistry & Biochemistry, University of Windsor , 401 Sunset Avenue, Windsor, OntarioN9B 3P4, Canada.
基p-NCC6F4CNSSN• (1) 存在于两个阶段,α和β,可以通过受控升华选择性地制备. α相表现出短距离的磁性秩序,而β相在更高的温度下更稳定.
科学领域:
- 材料科学
- 固态化学
- 磁化学
背景情况:
- 基是含有和硫的化合物,具有有趣的电子和磁性.
- 有机基的多态性可以导致不同的物理特征.
- 了解相位行为对于控制材料属性至关重要.
研究的目的:
- 研究 thiazyl 基 p-NCC6F4CNSSN• (1) 的α-和β-阶段的合成和表征.
- 确定α和β相之间的热性质和相变.
- 探索α相中的磁性特性和磁性排序.
主要方法:
- 在不同的基质温度下通过受控化进行选择性结晶.
- 差分扫描热量计 (DSC) 用于热分析和相位过渡的确定.
- 红外 (IR) 和拉曼光谱用于相差分辨.
- 测量磁性易感性 (dc和ac) 和测量热容量以探测磁性排序.
主要成果:
- (1) 的α相在-10°C以下结晶,而β相在环境温度或以上形成.
- 在111-117°C时,α相通过融化再结晶转化为β相;β相在167-170°C时融化.
- 红外光谱和拉曼光谱有效地区分α和β相.
- 该α相显示了8K左右的短距离磁性秩序,由磁性易感性和热容量最大值证明,但缺乏长距离磁性秩序.
结论:
- 通过精确控制化条件,可以合成基 (1) 的不同α和β相.
- 两个阶段的相位转换和热稳定性都得到了很好的定义.
- 在研究条件下,α相表现出短距离磁顺序的特征,但没有观察到长距离磁顺序.
更多相关视频
08:55Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
08:42High-Sensitivity Nuclear Magnetic Resonance at Giga-Pascal Pressures: A New Tool for Probing Electronic and Chemical Properties of Condensed Matter under Extreme Conditions
Published on: October 10, 2014
相关概念视频
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
Metallic Solids
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability....
Atomic Nuclei: Nuclear Spin State Population Distribution
Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
Valence Bond Theory
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
