Video Experimental Relacionado

Updated: May 30, 2026

Determining the Mechanical Strength of Ultra-Fine-Grained Metals

Determining the Mechanical Strength of Ultra-Fine-Grained Metals

Published on: November 22, 2021

Diseño racional de materiales con extrema compresibilidad negativa: frustración selectiva del modo blando en

Andrew B Cairns¹, Amber L Thompson, Matthew G Tucker

¹Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, UK.

Journal of the American Chemical Society

|July 23, 2011

Resumen

KMn[Ag(CN)2]3 muestra una notable compresibilidad lineal negativa (NLC) y una expansión térmica negativa anisotrópica (NTE). Su mecanismo único de "rack de vino" se expande a lo largo de un eje mientras se contrae a lo largo de otro bajo presión.

Área de la Ciencia:

Ciencia de los materiales Ciencia de los materiales.
La cristalografía es una técnica de cristalografía.
Física del estado sólido Física del estado sólido

Sus antecedentes:

La compresibilidad lineal negativa (NLC) es un fenómeno raro en el que un material se contrae en una dirección bajo presión hidrostática.
Comprender los mecanismos detrás de NLC es crucial para diseñar nuevos materiales con propiedades mecánicas únicas.

Objetivo del estudio:

Para investigar el efecto NLC en KMn[Ag(CN) 2) 3.3.
Para aclarar el mecanismo cristalográfico subyacente responsable de NLC y su relación con la expansión térmica.
Evaluar el papel de los counteriones en la modulación de estas propiedades.

Principales métodos:

Se empleó difracción de polvo de neutrones a presión variable para estudiar los cambios en la estructura cristalina bajo presión hidrostática.
El análisis de los parámetros de la red y los modos de fonón proporcionó información sobre la respuesta del material.

Principales resultados:

KMn[Ag(CN) 2 3 exhibe el NLC más fuerte observado hasta la fecha en un rango de presión extendido.
Se identificó un mecanismo similar a un "rack de vino", que causa expansión a lo largo del eje c y contracción a lo largo del eje a.
Se observó una expansión térmica negativa anisotrópica (NTE), vinculada al mismo mecanismo.

Conclusiones:

KMn[Ag(CN)2]3 es un excelente ejemplo de un material que exhibe significativos NLC y NTE.
Los counterions (K +) tienen un impacto limitado en la flexibilidad del marco, pero influyen en los modos de fonón críticos para NLC.
Este estudio proporciona una comprensión más profunda de los mecanismos de NLC y el potencial para el diseño de materiales.

Más Videos Relacionados

An Available Technique for Preparation of New Cast MnCuNiFeZnAl Alloy with Superior Damping Capacity and High Service Temperature

An Available Technique for Preparation of New Cast MnCuNiFeZnAl Alloy with Superior Damping Capacity and High Service Temperature

Published on: September 23, 2018

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Published on: June 7, 2018

Videos de Conceptos Relacionados

Crystal Field Theory - Octahedral Complexes

Crystal Field Theory - Octahedral Complexes

Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...

Stress-Strain Diagram - Brittle Materials

Stress-Strain Diagram - Brittle Materials

Brittle materials, including glass, cast iron, and stone, exhibit unique characteristics. They fracture without considerable change in their elongation rate, indicating that their breaking and ultimate strength are equivalent. Such materials also show lower strain levels at the point of rupture. The failure in brittle materials predominantly results from normal stresses, as evidenced by the rupture created along a surface perpendicular to the applied load. These materials do not display...

Yield Criteria for Ductile Materials under Plane Stress

Yield Criteria for Ductile Materials under Plane Stress

In designing structural elements and machine parts using ductile materials, it is crucial to ensure that these components withstand applied stresses without yielding. Yielding is initially determined through a tensile test, which evaluates the material's response to uniaxial stress. However, tensile stress is insufficient when components face biaxial or plane stress conditions This condition requires advanced criteria to predict failure.
The Maximum Shearing Stress Criterion, also known as the...

Stress-Strain Diagram - Ductile Materials

Stress-Strain Diagram - Ductile Materials

The stress-strain relationship in ductile materials such as structural steel or aluminium is intricate and progresses through several stages. When a specimen is loaded, it initially exhibits a linear length increase, depicted by a steep straight line on the stress-strain diagram. It indicates the material is elastically deforming and will return to its original shape once unloaded. However, when a critical stress value is reached, plastic deformation begins. This stage sees substantial...

Negative Regulator Molecules

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.

Crystal Field Theory - Tetrahedral and Square Planar Complexes

Crystal Field Theory - Tetrahedral and Square Planar Complexes

Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...