居里点

content: Below the Curie temperature, the atoms are aligned and parallel, causing spontaneous magnetism; the material is ferromagnetic. Above the Curie temperature the material is paramagnetic, as the atoms lose their ordered magnetic moments when the material undergoes a phase transition.
title: 亚铁磁性.
content: Materials are only ferrimagnetic below their corresponding Curie temperature. Ferrimagnetic materials are magnetic in the absence of an applied magnetic field and are made up of two different 离子.  Below the Curie temperature the atoms of each ion are aligned anti-parallel with different momentums causing a spontaneous magnetism; the material is ferrimagnetic. Above the Curie temperature the material is paramagnetic as the atoms lose their ordered magnetic moments as the material undergoes a phase transition.  The material has equal magnetic moments aligned in opposite directions resulting in a zero magnetic moment and a net magnetism of zero at all temperatures below the Néel temperature. Antiferromagnetic materials are weakly magnetic in the absence or presence of an applied magnetic field.  The Curie–Weiss law is a simple model derived from a mean-field approximation, this means it works well for the materials temperature,, much greater than their corresponding Curie temperature,, i.e. ; however fails to describe the magnetic susceptibility,, in the immediate vicinity of the Curie point because of local fluctuations between atoms.
title: 从上方接近居里温度.
content: As the Curie–Weiss law is an approximation, a more accurate model is needed when the temperature,, approaches the material's Curie temperature,.  Magnetic susceptibility occurs above the Curie temperature.  The spontaneous magnetism approaches zero as the temperature increases towards the materials Curie temperature.
title: 接近绝对零度(0开尔文).
content: The spontaneous magnetism, occurring in ferromagnetic, ferrimagnetic and antiferromagnetic materials, approaches zero as the temperature increases towards the material's Curie temperature. Spontaneous magnetism is at its maximum as the temperature approaches 0 K. That is, the magnetic moments are completely aligned and at their strongest magnitude of magnetism due to no thermal disturbance.
title: Weiss磁畴和表面和体积居里温度.
content: Materials structures consist of intrinsic magnetic moments which are separated into domains called Weiss domains. This can result in ferromagnetic materials having no spontaneous magnetism as domains could potentially balance each other out. The position of particles can therefore have different orientations around the surface than the main part (bulk) of the material. This property directly affects the Curie temperature as there can be a bulk Curie temperature and a different surface Curie temperature for a material.  The alignment of magnetic moments in the composite material affects the Curie temperature. If the materials moments are parallel with each other the Curie temperature will increase and if perpendicular the Curie temperature will decrease as either more or less thermal energy will be needed to destroy the alignments.  The density of nanocomposite materials changes the Curie temperature. Nanocomposites are compact structures on a nano-scale. The structure is built up of high and low bulk Curie temperatures, however will only have one mean-field Curie temperature. A higher density of lower bulk temperatures results in a lower mean-field Curie temperature and a higher density of higher bulk temperature significantly increases the mean-field Curie temperature. In more than one dimension the Curie temperature begins to increase as the magnetic moments will need more thermal energy to overcome the ordered structure.
title: 铁电材料中的居里温度.
content: In analogy to ferromagnetic and paramagnetic materials, the term Curie temperature () is also applied to the temperature at which a ferroelectric material transitions to being paraelectric. Hence, is the temperature where ferroelectric materials lose their spontaneous polarisation as a first or second order phase change occurs. In case of a second order transition the Curie Weiss temperature which defines the maximum of the dielectric constant is equal to the Curie temperature. However, the Curie temperature can be 10 K higher than in case of a first order transition.

Summary: 居里点(Curie point)又作居里温度(Curie temperature,Tc)或磁性转变点。是指磁性材料中自发磁化强度降到零时的温度,是铁磁性或亚铁磁性物质转变成顺磁性物质的临界点。低于居里点温度时该物质成为铁磁体,此时和材料有关的磁场很难改变。当温度高于居里点时,该物质成为顺磁体,磁体的磁场很容易随周围磁场的改变而改变。这时的磁敏感度约为10。居里点由物质的化学成分和晶体结构决定。

Curie temperature: In physics and materials science, the Curie temperature ("T"), or Curie point, is the temperature above which certain materials lose their permanent magnetic properties, which can (in most cases) be replaced by induced magnetism. The Curie temperature is named after Pierre Curie, who showed that magnetism was lost at a critical temperature.