Single crystal

About: Single crystal is a research topic. Over the lifetime, 59617 publications have been published within this topic receiving 870828 citations.

Three-Way Crystal-to-Crystal Reversible Transformation and Controlled Spin Switching by a Nonporous Molecular Material

Abstract: Porous materials capable of hosting external molecules are paramount in basic and applied research. Nonporous materials able to incorporate molecules via internal lattice reorganization are however extremely rare since their structural integrity usually does not resist the guest exchange processes. The novel heteroleptic low-spin Fe(II) complex [Fe(bpp)(H2L)](ClO4)2·1.5C3H6O (1; bpp = 2,6-bis(pyrazol-3-yl)pyridine, H2L = 2,6-bis(5-(2-methoxyphenyl)pyrazol-3-yl)pyridine) crystallizes as a compact discrete, nonporous material hosting solvate molecules of acetone. The system is able to extrude one-third of these molecules to lead to [Fe(bpp)(H2L)](ClO4)2·C3H6O (2), switching to the high-spin state while experiencing a profound crystallographic change. Compound 2 can be reversed to the original material upon reabsorption of acetone. Single crystal X-ray diffraction experiments on the latter system (1′) and on 2 show that these are reversible single-crystal-to-single-crystal (SCSC) transformations. Likewise, c...

Extended X-Ray-Absorption Fine Structure of Surface Atoms on Single-Crystal Substrates: Iodine Adsorbed on Ag(111)

Abstract: An Auger variant of the x-ray-absorption fine-structure (EXAFS) technique has been successfully applied to study the adsorption site and adsorbate-substrate bond length in a single-crystal system. The surface-EXAFS technique should have widespread applications in surface crystallographic studies.

Oxygen-vacancy-related dielectric relaxations in SrTiO3 at high temperatures

Abstract: We herein present comparative investigation on the dielectric properties of both ceramic and single crystal SrTiO3 samples in the temperature from room temperature to 1073 K. Two relaxations were observed in both samples. They behave as Debye-like and relaxor-like relaxations in ceramic and single crystal samples, respectively. These relaxations were found to be bulk effect related to oxygen-vacancy. In single crystal sample, the relaxations result from the long-range conduction associated with singly and doubly charged oxygen vacancies. In ceramic sample, the oxygen vacancies are more strongly localized in relation to the crystal. This leads to a new phenomenon of formation and dissociation of oxygen vacancy clusters before the vacancies make contribution to the long-range conduction. The low-temperature relaxation in ceramic sample was determined by the clustering and dissociating processes of the oxygen vacancies. The high-temperature relaxation in ceramic sample was found to share the same mechanism as that in the single crystal sample.

Crystal structures of pyridine and pyridine trihydrate

Abstract: The crystal structure of pyridine is orthorhombic with space group Pna21, a = 1752.4(3), b = 896.9(2), and c = 1135.2(2) pm at 153 K and Z = 16. A low melting crystalline hydrate of pyridine was found by DTA to be a trihydrate. It is orthorhombic, too, with space group Pbca, a = 1244.4(3), b = 1783.2(6), and c = 679.1(2) pm at 223 K and Z = 8. Both structures were determined from single crystal MoKα diffractometer data and refined to unweighted R values of 0.044 for 2769 and of 0.074 for 932 observed independent reflections. Most apparent in the anhydrous structure is an arrangement of the molecular noncrystallogrpahic twofold axes in layers perpendicular to the c‐axis direction and separated by c/4. With the ring centers not far from the points of a bcc lattice a ’’molecular coordination number’’ of 14 can be assigned to each of the four independent molecules. Their geometries are very similar and close to mm‐C2v symmetry. In the structure of the trihydrate the water molecules are O–H ⋅ ⋅ ⋅ O hydrogen bo...