Synthesis, Structure, and Properties of a New Family of Mixed-Framework Chalcohalide Semiconductors:  CdSbS2X (X = Cl, Br), CdBiS2X (X = Cl, Br), and CdBiSe2X (X = Br, I)

2006 ◽  
Vol 18 (5) ◽  
pp. 1219-1225 ◽  
Author(s):  
Lei Wang ◽  
Yi-Chung Hung ◽  
Shiou-Jyh Hwu ◽  
Hyun-Joo Koo ◽  
M.-H. Whangbo
Keyword(s):  
Structure And Properties ◽  
New Family ◽  
Mixed Framework

scholarly journals A Non-alternant Aromatic Belt: Methylene-bridged [6]Cycloparaphenylene Synthesized from Pillar[6]arene

2020 ◽  
Author(s):  
Yuanming Li ◽  
Yasutomo Segawa ◽  
Akiko Yagi ◽  
Kenichiro Itami
Keyword(s):  
Small Molecules ◽  
Strain Energy ◽  
Energy Gap ◽  
Internal Strain ◽  
Supramolecular Architecture ◽  
Structure And Properties ◽  
Efficient Strategy ◽  
New Family

The synthesis, structure, and properties of <a>methylene-bridged [6]cycloparaphenylene ([6]CPP), a non-alternant aromatic belt,</a> are described. This belt-shaped methylene-bridged [6]CPP, in which each phenylene unit is tethered to its neighbors by methylene bridges, was constructed through six-fold intramolecular nickel-mediated aryl-aryl coupling of <a>triflate-functionalized pillar[6]arene </a>in 15% isolated yield. <a>Compared with the analogous [6]CPP, the methylene bridges co-planarize neighboring paraphenylene units and enhance the degree of </a>p-conjugation, resulting in a significant decrease in energy gap. Moreover, the incorporation of small molecules in the defined pocket of methylene-bridged [6]CPP makes it an attractive supramolecular architecture. Methylene-bridged [6]CPP is characterized by high internal strain energy reaching 110.2 kcal·mol<sup>–1</sup>, attributed to its restricted structure. This work not only exhibits an efficient strategy to construct a new family of aromatic belt, but also showcases their properties, which combine the merits of CPPs and pillararenes.

scholarly journals Hybrid organic-inorganic perovskites: a spin-off of oxidic perovskites

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
A. Garcia ◽  
E.J. Juarez-Perez ◽  
S. Castro-Garcia ◽  
M. Sanchez-Andujar ◽  
M.A. Senaris-Rodriguez
Keyword(s):  
Crystal Structure ◽  
Perovskite Structure ◽  
Structure And Properties ◽  
Novel Materials ◽  
New Family ◽  
Final Goal ◽  
Young Family

ABX3 compounds with perovskite structure have been intensively and extensively studied in the last decades in view of their structural richness and amazing variety of interesting properties, such as piezoelectricity, ferroelectricity, ferromagnetism, superconductivity, magnetoresistance, multiferroicity, etc. In this chapter, we recompile well-established chemical and structural concepts in pure inorganic perovskites (mainly oxidic perovskites), and extend them to the young family of hybrid organic-inorganic perovskites. Our final goal is to help understanding the relationships among composition, crystal structure and properties in this new family of compounds, for inspiring further the design of novel materials.

scholarly journals A Non-alternant Aromatic Belt: Methylene-bridged [6]Cycloparaphenylene Synthesized from Pillar[6]arene

2020 ◽  
Author(s):  
Yuanming Li ◽  
Yasutomo Segawa ◽  
Akiko Yagi ◽  
Kenichiro Itami
Keyword(s):  
Small Molecules ◽  
Strain Energy ◽  
Energy Gap ◽  
Internal Strain ◽  
Supramolecular Architecture ◽  
Structure And Properties ◽  
Efficient Strategy ◽  
New Family

The synthesis, structure, and properties of <a>methylene-bridged [6]cycloparaphenylene ([6]CPP), a non-alternant aromatic belt,</a> are described. This belt-shaped methylene-bridged [6]CPP, in which each phenylene unit is tethered to its neighbors by methylene bridges, was constructed through six-fold intramolecular nickel-mediated aryl-aryl coupling of <a>triflate-functionalized pillar[6]arene </a>in 15% isolated yield. <a>Compared with the analogous [6]CPP, the methylene bridges co-planarize neighboring paraphenylene units and enhance the degree of </a>p-conjugation, resulting in a significant decrease in energy gap. Moreover, the incorporation of small molecules in the defined pocket of methylene-bridged [6]CPP makes it an attractive supramolecular architecture. Methylene-bridged [6]CPP is characterized by high internal strain energy reaching 110.2 kcal·mol<sup>–1</sup>, attributed to its restricted structure. This work not only exhibits an efficient strategy to construct a new family of aromatic belt, but also showcases their properties, which combine the merits of CPPs and pillararenes.

Structure of second phases in TiAl alloys containing Cr and B

1991 ◽  
Vol 49 ◽  
pp. 576-577
Author(s):  
Ernest L. Hall ◽  
Shyh-Chin Huang
Keyword(s):  
Grain Size ◽  
Second Phase ◽  
Structure And Properties ◽  
Tial Alloys ◽  
Second Phases ◽  
Interstitial Elements

Addition of interstitial elements to γ-TiAl alloys is currently being explored as a method for improving the properties of these alloys. Previous work in which a number of interstitial elements were studied showed that boron was particularly effective in refining the grain size in castings, and led to enhanced strength while maintaining reasonable ductility. Other investigators have shown that B in γ-TiAl alloys tends to promote the formation of TiB2 as a second phase. In this study, the microstructure of Bcontaining TiAl alloys was examined in detail in order to describe the mechanism by which B alters the structure and properties of these alloys.

Relationships between hierarchical structure and properties in macromolecular systems

1987 ◽  
Vol 45 ◽  
pp. 440-443
Author(s):  
E. Baer
Keyword(s):  
Uniaxial Tension ◽  
Hierarchical Structure ◽  
Inorganic Material ◽  
Hierarchical Structures ◽  
Bone Collagen ◽  
Structure And Properties ◽  
Connective Tissues ◽  
Scale Level ◽  
Fibrous Protein ◽  
Macromolecular Systems

The most advanced macromolecular materials are found in plants and animals, and certainly the connective tissues in mammals are amongst the most advanced macromolecular composites known to mankind. The efficient use of collagen, a fibrous protein, in the design of both soft and hard connective tissues is worthy of comment. Very crudely, in bone collagen serves as a highly efficient binder for the inorganic hydroxyappatite which stiffens the structure. The interactions between the organic fiber of collagen and the inorganic material seem to occur at the nano (scale) level of organization. Epitatic crystallization of the inorganic phase on the fibers has been reported to give a highly anisotropic, stress responsive, structure. Soft connective tissues also have sophisticated oriented hierarchical structures. The collagen fibers are “glued” together by a highly hydrated gel-like proteoglycan matrix. One of the simplest structures of this type is tendon which functions primarily in uniaxial tension as a reinforced elastomeric cable between muscle and bone.

Microstructure and crystal symmetry of Pb2Sr2(Y/Ca)Cu3O9−δ

1990 ◽  
Vol 48 (4) ◽  
pp. 64-65
Author(s):  
Y. P. Lin ◽  
J. S. Xue ◽  
J. E. Greedan
Keyword(s):  
Electron Diffraction ◽  
High Temperature Superconductors ◽  
Carbon Film ◽  
Basic Structure ◽  
Crystal Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Groups ◽  
New Family ◽  
Convergent Beam

A new family of high temperature superconductors based on Pb2Sr2YCu3O9−δ has recently been reported. One method of improving Tc has been to replace Y partially with Ca. Although the basic structure of this type of superconductors is known, the detailed structure is still unclear, and various space groups has been proposed. In our work, crystals of Pb2Sr2YCu3O9−δ with dimensions up to 1 × 1 × 0.25.mm and with Tc of 84 K have been grown and their superconducting properties described. The defects and crystal symmetry have been investigated using electron microscopy performed on crushed crystals supported on a holey carbon film.Electron diffraction confirmed x-ray diffraction results which showed that the crystals are primitive orthorhombic with a=0.5383, b=0.5423 and c=1.5765 nm. Convergent Beam Electron Diffraction (CBED) patterns for the and axes are shown in Figs. 1 and 2 respectively.

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