阿尔法和β-A2Hg3M2S8 (A = K,Rb;M = Ge,Sn):极四元基因化物,具有强烈的非线性光学响应
J-H Liao1, G M Marking, K F Hsu
1Department of Chemistry and Center for Fundamental Materials Research, Michigan State University, East Lansing, Michigan 48824-1322, USA.
Journal of the American Chemical Society
|August 2, 2003
概括
新的金属硫化化合物 (A2Hg3M2S8) 呈现出独特的晶体结构和强大的非线性光学特性. 这些宽半导体显示出出色的热稳定性和高激光损伤值,用于先进的应用.
科学领域:
- 固态化学 固态化学
- 材料科学是一种材料科学.
- 晶体学 晶体学是指结晶学.
背景情况:
- 发现具有理想光学和电子性能的新材料对于技术进步至关重要.
- 性多化物流量法使新型化合物的合成成为可能.
- 极地非中心对称的晶体结构是非线性光学应用的关键.
研究的目的:
- 发现和描述A2Hg3M2S8化合物的新相.
- 研究它们的晶体学,光学,热学和非线性光学特性.
- 探索它们作为宽半导体和非线性光学材料的潜力.
主要方法:
- 性多化物流量方法用于晶体合成.
- 单晶X射线衍射用于结构确定.
- 光学光谱学 (UV-Vis-NIR),热分析 (TGA/DSC) 和非线性光学 (SHG) 测量.
主要成果:
- 发现具有新结构类型的α-和β-A2Hg3M2S8 (A=K,Rb;M=Ge,Sn) 阶段.
- 确定精确的晶体学数据的阿尔法 (正方形,Aba2) 和β (单临床,C2) 形式.
- 宽带间隙 (~2.40-2.64 eV),宽红外透明度 (高达14μm) 和高非线性系数 (d_eff ~20 pm/V对于β-K2Hg3Ge2S8) 的表征.
结论:
- 新发现的A2Hg3M2S8相具有独特的极性非中心对称结构.
- 由于强烈的SHG反应,这些材料显示出非线性光学应用的巨大潜力.
- 它们的宽带间隙,热稳定性和强度使它们成为光电子设备的有希望的候选者.
相关概念视频
03:05Acid Strength and Molecular Structure
Binary Acids and Bases
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
02:57Coordination Number and Geometry
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar.
02:52Stereoisomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
03:02Colors and Magnetism
Color in Coordination Complexes
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 eye.
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 eye.
02:16Lewis Acids and Bases
This lesson delves into Lewis acids and bases in the context of the octet rule for electron-deficient compounds. Here, the concept is discussed, emphasizing the group 13 elements like boron or aluminium. Since group 13 elements possess three valence electrons, they form trivalent compounds with a sextet of electrons and a vacant orbital for the central atom. Consequently, these electron-deficient compounds accept electrons from other species to complete their octet in a chemical reaction. They...
02:42Acidity of 1-Alkynes
The acidic strength of hydrocarbons follows the order: Alkynes > Alkenes > Alkanes. The strength of an acid is commonly expressed in units of pKa — the lower the pKa, the stronger the acid. Among the hydrocarbons, terminal alkynes have lower pKa values and are, therefore, more acidic. For example, the pKa values for ethane, ethene, and acetylene are 51, 44, and 25, respectively, as shown here.