"Crystalline" redirects here. For the Björk song, see Crystalline (song). "Crystalline"在此处被重定向。关于Björk的歌曲,请参见Crystalline (歌曲)。
Crystals of amethystquartz 紫水晶石英的晶体Microscopically, a single crystal has atoms in a near-perfect periodic arrangement; a polycrystal is composed of many microscopic crystals (called "crystallites" or "grains"); and an amorphous solid (such as glass) has no periodic arrangement even microscopically. 从微观角度看,单晶体的原子几乎呈完美的周期性排列;多晶体则由许多微观晶体(称为"晶粒"或"颗粒")组成;而无定形固体(如玻璃)即使在微观层面上也没有周期性排列。
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macroscopic single crystals are usually identifiable by their geometrical shape, consisting of flat faces with specific, characteristic orientations. The scientific study of crystals and crystal formation is known as crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification. 水晶或晶体固体是一种固态材料,其构成元素(如原子,分子或离子)以高度有序的微观结构排列,形成一个在所有方向上延伸的晶格。此外,宏观的单晶通常可以通过其几何形状来识别,由具有特定,特征性方向的平面面组成。对晶体和晶体形成的科学研究被称为晶体学。通过晶体生长机制进行晶体形成的过程被称为结晶或固化。
The word crystal derives from the Ancient Greek word κρύσταλλος (krustallos), meaning both "ice" and "rock crystal", from κρύος (kruos), "icy cold, frost". “Crystal”这个词源自古希腊语的“κρύσταλλος”(krustallos),意为“冰”和“岩石水晶”,源于“κρύος”(kruos),意为“冰冷,霜冻”。
Examples of large crystals include snowflakes, diamonds, and table salt. Most inorganic solids are not crystals but polycrystals, i.e. many microscopic crystals fused together into a single solid. Polycrystals include most metals, rocks, ceramics, and ice. A third category of solids is amorphous solids, where the atoms have no periodic structure whatsoever. Examples of amorphous solids include glass, wax, and many plastics. 大晶体的例子包括雪花、钻石和食盐。大多数无机固体不是晶体,而是多晶体,即许多微观晶体融合成一个单一的固体。多晶体包括大多数金属、岩石、陶瓷和冰。第三类固体是无定形固体,其中的原子没有任何周期性结构。无定形固体的例子包括玻璃、蜡和许多塑料。
Despite the name, lead crystal, crystal glass, and related products are not crystals, but rather types of glass, i.e. amorphous solids. 尽管名字如此,铅晶、水晶玻璃以及相关产品并非晶体,而是一种类型的玻璃,即无定形固体。
Crystals, or crystalline solids, are often used in pseudoscientific practices such as crystal therapy, and, along with gemstones, are sometimes associated with spellwork in Wiccan beliefs and related religious movements. 水晶或晶体固体常常被用于像水晶疗法这样的伪科学实践中,同时,它们和宝石一样,有时会与巫术信仰以及相关的宗教运动中的咒语工作相关联。
Macroscopic (~16 cm) halite crystal. The right-angles between crystal faces are due to the cubic symmetry of the atoms' arrangement 宏观(约16厘米)的岩盐晶体。晶体面之间的直角是由于原子排列的立方对称性所致。
The scientific definition of a "crystal" is based on the microscopic arrangement of atoms inside it, called the crystal structure. A crystal is a solid where the atoms form a periodic arrangement. (Quasicrystals are an exception, see below). “晶体”的科学定义基于其内部原子的微观排列,这种排列被称为晶体结构。晶体是一种固体,其中原子形成周期性排列。(准晶体是个例外,详见下文)。
Not all solids are crystals. For example, when liquid water starts freezing, the phase change begins with small ice crystals that grow until they fuse, forming a polycrystalline structure. In the final block of ice, each of the small crystals (called "crystallites" or "grains") is a true crystal with a periodic arrangement of atoms, but the whole polycrystal does not have a periodic arrangement of atoms, because the periodic pattern is broken at the grain boundaries. Most macroscopic inorganic solids are polycrystalline, including almost all metals, ceramics, ice, rocks, etc. Solids that are neither crystalline nor polycrystalline, such as glass, are called amorphous solids, also called glassy, vitreous, or noncrystalline. These have no periodic order, even microscopically. There are distinct differences between crystalline solids and amorphous solids: most notably, the process of forming a glass does not release the latent heat of fusion, but forming a crystal does. 并非所有的固体都是晶体。例如,当液态水开始冻结时,相变首先从小冰晶开始,这些冰晶会增长直到它们融合,形成多晶结构。在最后的冰块中,每一个小晶体(被称为"晶粒"或"颗粒")都是一个真正的晶体,具有周期性的原子排列,但整个多晶体并没有周期性的原子排列,因为在颗粒边界处,周期性模式被打破。大多数宏观无机固体都是多晶体,包括几乎所有的金属、陶瓷、冰、岩石等。那些既不是晶体也不是多晶体的固体,如玻璃,被称为非晶固体,也被称为玻璃状、玻璃质或非晶体。这些物质没有周期性的排列,即使在微观层面上也是如此。晶体固体和非晶固体之间存在明显的差异:最值得注意的是,形成玻璃的过程不会释放潜热,但形成晶体则会。
A crystal structure (an arrangement of atoms in a crystal) is characterized by its unit cell, a small imaginary box containing one or more atoms in a specific spatial arrangement. The unit cells are stacked in three-dimensional space to form the crystal. 晶体结构(晶体中原子的排列方式)的特征在于其单位晶胞,这是一个包含一个或多个原子在特定空间排列的小型虚构盒子。单位晶胞在三维空间中堆叠,形成晶体。
The symmetry of a crystal is constrained by the requirement that the unit cells stack perfectly with no gaps. There are 219 possible crystal symmetries (230 is commonly cited, but this treats chiral equivalents as separate entities), called crystallographic space groups. These are grouped into 7 crystal systems, such as cubic crystal system (where the crystals may form cubes or rectangular boxes, such as halite shown at right) or hexagonal crystal system (where the crystals may form hexagons, such as ordinary water ice). 晶体的对称性受到单元格完美堆叠无间隙的要求的限制。有219种可能的晶体对称性(常常被引用的是230种,但这将手性等价物视为独立的实体),被称为晶体学空间群。这些被分为7种晶体系统,如立方晶体系统(其中晶体可能形成立方体或矩形盒子,如右图所示的卤石)或六角晶体系统(其中晶体可能形成六边形,如普通的水冰)。
Crystal faces, shapes and crystallographic forms 晶体面,形状和晶体学形式
As a halite crystal is growing, new atoms can very easily attach to the parts of the surface with rough atomic-scale structure and many dangling bonds. Therefore, these parts of the crystal grow out very quickly (yellow arrows). Eventually, the whole surface consists of smooth, stable faces, where new atoms cannot as easily attach themselves. 当卤石晶体在生长时,新的原子可以非常容易地附着到表面粗糙的原子级结构和许多悬空键的部分。因此,这些部分的晶体生长非常快(黄色箭头)。最终,整个表面都由平滑、稳定的面构成,新的原子不能那么容易地附着在上面。
Crystals are commonly recognized, macroscopically, by their shape, consisting of flat faces with sharp angles. These shape characteristics are not necessary for a crystal—a crystal is scientifically defined by its microscopic atomic arrangement, not its macroscopic shape—but the characteristic macroscopic shape is often present and easy to see. 晶体通常被宏观地识别为具有尖锐角度的平面形状。这些形状特征并非晶体所必需的——科学上定义晶体的是其微观的原子排列,而非其宏观形状——但这种特征性的宏观形状往往存在且易于观察。
Euhedral crystals are those that have obvious, well-formed flat faces. Anhedral crystals do not, usually because the crystal is one grain in a polycrystalline solid. 显晶体是那些具有明显、形成良好的平面面的晶体。无晶面晶体则通常没有,这通常是因为晶体是多晶固体中的一粒。
The flat faces (also called facets) of a euhedral crystal are oriented in a specific way relative to the underlying atomic arrangement of the crystal: they are planes of relatively low Miller index. This occurs because some surface orientations are more stable than others (lower surface energy). As a crystal grows, new atoms attach easily to the rougher and less stable parts of the surface, but less easily to the flat, stable surfaces. Therefore, the flat surfaces tend to grow larger and smoother, until the whole crystal surface consists of these plane surfaces. (See diagram on right.) 一颗完整晶体的平面面(也称为切面)是以特定方式相对于晶体的基础原子排列进行定向的:它们是相对较低的米勒指数的平面。这是因为某些表面取向比其他的更稳定(表面能量较低)。随着晶体的生长,新的原子容易附着在表面粗糙且不稳定的部分,但不容易附着在平坦、稳定的表面。因此,平坦的表面倾向于变得更大更光滑,直到整个晶体表面都由这些平面构成。(请参见右侧图示。)
One of the oldest techniques in the science of crystallography consists of measuring the three-dimensional orientations of the faces of a crystal, and using them to infer the underlying crystal symmetry. 晶体学科学中最古老的技术之一包括测量晶体面的三维取向,并用它们来推断潜在的晶体对称性。
A crystal's crystallographic forms are sets of possible faces of the crystal that are related by one of the symmetries of the crystal. For example, crystals of galena often take the shape of cubes, and the six faces of the cube belong to a crystallographic form that displays one of the symmetries of the isometric crystal system. Galena also sometimes crystallizes as octahedrons, and the eight faces of the octahedron belong to another crystallographic form reflecting a different symmetry of the isometric system. A crystallographic form is described by placing the Miller indices of one of its faces within brackets. For example, the octahedral form is written as {111}, and the other faces in the form are implied by the symmetry of the crystal. 晶体的晶体学形态是晶体可能的面的集合,这些面通过晶体的某种对称性相互关联。例如,方铅矿的晶体通常呈立方形,立方体的六个面属于一个显示等轴晶系对称性的晶体学形态。方铅矿有时也会以八面体形态结晶,八面体的八个面属于另一个反映等轴晶系不同对称性的晶体学形态。晶体学形态是通过将其一个面的米勒指数放在括号内来描述的。例如,八面体形态写作{111},形态中的其他面由晶体的对称性暗示。
Forms may be closed, meaning that the form can completely enclose a volume of space, or open, meaning that it cannot. The cubic and octahedral forms are examples of closed forms. All the forms of the isometric system are closed, while all the forms of the monoclinic and triclinic crystal systems are open. A crystal's faces may all belong to the same closed form, or they may be a combination of multiple open or closed forms. 形态可以是封闭的,意味着形态可以完全包围一个空间体积,或者是开放的,意味着它不能。立方形和八面体形态是封闭形态的例子。等轴晶系的所有形态都是封闭的,而单斜晶系和三斜晶系的所有形态都是开放的。一个晶体的各个面可能都属于同一封闭形态,或者它们可能是多个开放或封闭形态的组合。
A crystal's habit is its visible external shape. This is determined by the crystal structure (which restricts the possible facet orientations), the specific crystal chemistry and bonding (which may favor some facet types over others), and the conditions under which the crystal formed. 晶体的习性是其可见的外部形状。这由晶体结构(限制可能的切面方向)、特定的晶体化学和键合(可能偏好某些切面类型而不是其他类型),以及晶体形成的条件决定。
By volume and weight, the largest concentrations of crystals in the Earth are part of its solid bedrock. Crystals found in rocks typically range in size from a fraction of a millimetre to several centimetres across, although exceptionally large crystals are occasionally found. As of 1999, the world's largest known naturally occurring crystal is a crystal of beryl from Malakialina, Madagascar, 18 m (59 ft) long and 3.5 m (11 ft) in diameter, and weighing 380,000 kg (840,000 lb). 从体积和重量来看,地球中最大的晶体集中在其坚硬的基岩中。在岩石中发现的晶体通常大小从毫米的一部分到几厘米不等,尽管偶尔也会发现特别大的晶体。截至1999年,世界上已知最大的天然晶体是来自马达加斯加的马拉基亚利纳的绿柱石晶体,长18米(59英尺),直径3.5米(11英尺),重380,000公斤(840,000磅)。
Some crystals have formed by magmatic and metamorphic processes, giving origin to large masses of crystalline rock. The vast majority of igneous rocks are formed from molten magma and the degree of crystallization depends primarily on the conditions under which they solidified. Such rocks as granite, which have cooled very slowly and under great pressures, have completely crystallized; but many kinds of lava were poured out at the surface and cooled very rapidly, and in this latter group a small amount of amorphous or glassy matter is common. Other crystalline rocks, the metamorphic rocks such as marbles, mica-schists and quartzites, are recrystallized. This means that they were at first fragmental rocks like limestone, shale and sandstone and have never been in a molten condition nor entirely in solution, but the high temperature and pressure conditions of metamorphism have acted on them by erasing their original structures and inducing recrystallization in the solid state. 有些晶体是通过岩浆和变质过程形成的,产生了大量的结晶岩石。绝大多数的火成岩是由熔融的岩浆形成的,其结晶程度主要取决于它们凝固的条件。像花岗岩这样的岩石,由于在极大的压力下非常慢地冷却,已经完全结晶化;但是许多种类的熔岩是在地表倾泻出来并且非常快速地冷却,而在这后一组中,少量的无定形或玻璃质物质是常见的。其他的结晶岩石,像大理石、云母片岩和石英岩这样的变质岩,是经过重结晶的。这意味着它们最初是像石灰石、页岩和砂岩这样的碎屑岩,从未处于熔融状态,也未完全溶解,但是变质的高温和高压条件已经通过抹去它们原有的结构并在固态中诱导重结晶。
Other rock crystals have formed out of precipitation from fluids, commonly water, to form druses or quartz veins. Evaporites such as halite, gypsum and some limestones have been deposited from aqueous solution, mostly owing to evaporation in arid climates. 其他的岩石晶体是由流体,通常是水,通过沉淀形成的,形成了晶簇或石英脉。像岩盐、石膏和一些石灰石这样的蒸发岩是由水溶液沉积形成的,主要是由于干旱气候中的蒸发。
Water-based ice in the form of snow, sea ice, and glaciers are common crystalline/polycrystalline structures on Earth and other planets. A single snowflake is a single crystal or a collection of crystals, while an ice cube is a polycrystal. Ice crystals may form from cooling liquid water below its freezing point, such as ice cubes or a frozen lake. Frost, snowflakes, or small ice crystals suspended in the air (ice fog) more often grow from a supersaturated gaseous-solution of water vapor and air, when the temperature of the air drops below its dew point, without passing through a liquid state. Another unusual property of water is that it expands rather than contracts when it crystallizes. 水基冰以雪、海冰和冰川的形式,是地球和其他行星上常见的晶体/多晶体结构。单个雪花是一个单晶体或一组晶体,而冰块则是多晶体。冰晶可能由冷却的液态水形成,其温度低于其冰点,例如冰块或冻结的湖泊。霜、雪花或悬浮在空气中的小冰晶(冰雾)更常从过饱和的水蒸气和空气的气态溶液中生长,当空气的温度降低到其露点以下,而无需经过液态。水的另一个不寻常的属性是,当它结晶时,它会扩张而不是收缩。
The same group of atoms can often solidify in many different ways. Polymorphism is the ability of a solid to exist in more than one crystal form. For example, water ice is ordinarily found in the hexagonal form Ice Ih, but can also exist as the cubic Ice Ic, the rhombohedralice II, and many other forms. The different polymorphs are usually called different phases. 同一组原子通常可以以许多不同的方式凝固。多晶形是固体存在于一种以上晶体形式的能力。例如,水冰通常以六方形的冰I h 形式存在,但也可以以立方形的冰I c ,菱形的冰II,以及许多其他形式存在。不同的多晶形通常被称为不同的相。
In addition, the same atoms may be able to form noncrystalline phases. For example, water can also form amorphous ice, while SiO2 can form both fused silica (an amorphous glass) and quartz (a crystal). Likewise, if a substance can form crystals, it can also form polycrystals. 此外,相同的原子也可能形成非晶相。例如,水也可以形成非晶冰,而SiO 2 可以形成熔融石英(一种非晶玻璃)和石英(一种晶体)。同样,如果一种物质可以形成晶体,那么它也可以形成多晶体。
For pure chemical elements, polymorphism is known as allotropy. For example, diamond and graphite are two crystalline forms of carbon, while amorphous carbon is a noncrystalline form. Polymorphs, despite having the same atoms, may have very different properties. For example, diamond is the hardest substance known, while graphite is so soft that it is used as a lubricant. Chocolate can form six different types of crystals, but only one has the suitable hardness and melting point for candy bars and confections. Polymorphism in steel is responsible for its ability to be heat treated, giving it a wide range of properties. 对于纯化学元素,多晶形被称为同素异形体。例如,钻石和石墨是碳的两种晶体形式,而非晶碳是一种非晶体形式。尽管具有相同的原子,但多晶形可能具有非常不同的性质。例如,钻石是已知的最硬物质,而石墨则柔软得可以用作润滑剂。巧克力可以形成六种不同类型的晶体,但只有一种具有适合糖果棒和糖果的硬度和熔点。钢的多晶形性质使其具有热处理的能力,从而具有广泛的性质。
Polyamorphism is a similar phenomenon where the same atoms can exist in more than one amorphous solid form. 多态性是一种相似的现象,其中相同的原子可以以多种非晶固态形式存在。
Crystallization is the process of forming a crystalline structure from a fluid or from materials dissolved in a fluid. (More rarely, crystals may be deposited directly from gas; see: epitaxy and frost.) 结晶化是从流体或溶解在流体中的物质形成晶体结构的过程。(更少见的是,晶体可能直接从气体中沉积;参见:外延和霜冻。)
Crystallization is a complex and extensively-studied field, because depending on the conditions, a single fluid can solidify into many different possible forms. It can form a single crystal, perhaps with various possible phases, stoichiometries, impurities, defects, and habits. Or, it can form a polycrystal, with various possibilities for the size, arrangement, orientation, and phase of its grains. The final form of the solid is determined by the conditions under which the fluid is being solidified, such as the chemistry of the fluid, the ambient pressure, the temperature, and the speed with which all these parameters are changing. 结晶化是一个复杂且被广泛研究的领域,因为根据条件的不同,单一的流体可以固化成许多不同的可能形态。它可以形成单晶,可能具有各种可能的相位、化学计量比、杂质、缺陷和习性。或者,它可以形成多晶,对于其晶粒的大小、排列、方向和相位有各种可能性。固态的最终形态由流体固化的条件决定,如流体的化学性质、环境压力、温度,以及所有这些参数变化的速度。
Specific industrial techniques to produce large single crystals (called boules) include the Czochralski process and the Bridgman technique. Other less exotic methods of crystallization may be used, depending on the physical properties of the substance, including hydrothermal synthesis, sublimation, or simply solvent-based crystallization. 产生大型单晶(称为布尔)的特定工业技术包括采用楚赫拉尔斯基法和布里奇曼技术。根据物质的物理属性,也可以使用其他不太复杂的结晶方法,包括水热合成、升华或简单的溶剂基结晶。
Large single crystals can be created by geological processes. For example, selenite crystals in excess of 10 m are found in the Cave of the Crystals in Naica, Mexico. For more details on geological crystal formation, see above. 大型单晶体可以通过地质过程形成。例如,在墨西哥的纳伊卡晶洞中,可以找到超过10米的硒石晶体。有关地质晶体形成的更多详细信息,请参见上文。
Crystals can also be formed by biological processes, see above. Conversely, some organisms have special techniques to prevent crystallization from occurring, such as antifreeze proteins. 晶体也可以通过生物过程形成,详情请参见上文。相反,一些生物具有特殊技术来防止结晶发生,例如抗冻蛋白。
An ideal crystal has every atom in a perfect, exactly repeating pattern. However, in reality, most crystalline materials have a variety of crystallographic defects, places where the crystal's pattern is interrupted. The types and structures of these defects may have a profound effect on the properties of the materials. 理想的晶体中,每个原子都处于完美的、精确重复的模式中。然而,实际上,大多数晶体材料都存在各种晶体缺陷,即晶体模式被打断的地方。这些缺陷的类型和结构可能对材料的性质产生深远影响。
A few examples of crystallographic defects include vacancy defects (an empty space where an atom should fit), interstitial defects (an extra atom squeezed in where it does not fit), and dislocations (see figure at right). Dislocations are especially important in materials science, because they help determine the mechanical strength of materials. 晶体缺陷的几个例子包括空位缺陷(原子应该填充的空位)、间隙缺陷(额外的原子被挤压在不适合的地方)和位错(参见右图)。位错在材料科学中尤其重要,因为它们有助于确定材料的机械强度。
Another common type of crystallographic defect is an impurity, meaning that the "wrong" type of atom is present in a crystal. For example, a perfect crystal of diamond would only contain carbon atoms, but a real crystal might perhaps contain a few boron atoms as well. These boron impurities change the diamond's color to slightly blue. Likewise, the only difference between ruby and sapphire is the type of impurities present in a corundum crystal. 另一种常见的晶体缺陷类型是杂质,意味着在晶体中存在"错误"类型的原子。例如,完美的钻石晶体只包含碳原子,但实际的晶体可能也包含一些硼原子。这些硼杂质会使钻石的颜色略微偏蓝。同样,红宝石和蓝宝石之间的唯一区别就是刚玉晶体中存在的杂质类型。
In semiconductors, a special type of impurity, called a dopant, drastically changes the crystal's electrical properties. Semiconductor devices, such as transistors, are made possible largely by putting different semiconductor dopants into different places, in specific patterns. 在半导体中,一种特殊类型的杂质,被称为掺杂剂,极大地改变了晶体的电性能。半导体设备,如晶体管,主要是通过在不同的地方,按照特定的模式放置不同的半导体掺杂剂来实现的。
Twinning is a phenomenon somewhere between a crystallographic defect and a grain boundary. Like a grain boundary, a twin boundary has different crystal orientations on its two sides. But unlike a grain boundary, the orientations are not random, but related in a specific, mirror-image way. 双晶是一种介于晶体缺陷和晶粒界面之间的现象。像晶粒界面一样,双晶界面的两侧具有不同的晶体取向。但与晶粒界面不同的是,这些取向并非随机的,而是以一种特定的镜像方式相关联。
Mosaicity is a spread of crystal plane orientations. A mosaic crystal consists of smaller crystalline units that are somewhat misaligned with respect to each other. 马赛克性是晶面取向的分散。马赛克晶体由相对彼此略有错位的较小晶体单位组成。
Chemical bonds化学键
In general, solids can be held together by various types of chemical bonds, such as metallic bonds, ionic bonds, covalent bonds, van der Waals bonds, and others. None of these are necessarily crystalline or non-crystalline. However, there are some general trends as follows: 一般来说,固体可以通过各种类型的化学键合在一起,例如金属键、离子键、共价键、范德华键等等。这些并不一定是晶体或非晶体。然而,有一些普遍的趋势如下:
Metals crystallize rapidly and are almost always polycrystalline, though there are exceptions like amorphous metal and single-crystal metals. The latter are grown synthetically, for example, fighter-jet turbines are typically made by first growing a single crystal of titanium alloy, increasing its strength and melting point over polycrystalline titanium. A small piece of metal may naturally form into a single crystal, such as Type 2 telluric iron, but larger pieces generally do not unless extremely slow cooling occurs. For example, iron meteorites are often composed of single crystal, or many large crystals that may be several meters in size, due to very slow cooling in the vacuum of space. The slow cooling may allow the precipitation of a separate phase within the crystal lattice, which form at specific angles determined by the lattice, called Widmanstatten patterns. 金属快速结晶,几乎总是多晶体,尽管也有像非晶金属和单晶金属这样的例外。后者是人工生长的,例如,战斗机涡轮机通常是首先生长出一个钛合金的单晶,以提高其强度和熔点,超过多晶钛。一小块金属可能自然形成为一个单晶,如2型地球铁,但较大的片段通常不会,除非发生极慢的冷却。例如,铁陨石通常由单晶或许多大晶体组成,这些晶体可能有几米大,这是由于在空间真空中非常慢的冷却。慢速冷却可能允许在晶格内沉淀出一个单独的相,这些相在由晶格决定的特定角度形成,被称为维特曼斯塔滕图案。
Ionic compounds typically form when a metal reacts with a non-metal, such as sodium with chlorine. These often form substances called salts, such as sodium chloride (table salt) or potassium nitrate (saltpeter), with crystals that are often brittle and cleave relatively easily. Ionic materials are usually crystalline or polycrystalline. In practice, large salt crystals can be created by solidification of a molten fluid, or by crystallization out of a solution. Some ionic compounds can be very hard, such as oxides like aluminium oxide found in many gemstones such as ruby and synthetic sapphire. 离子化合物通常在金属与非金属反应时形成,例如钠与氯的反应。这些反应通常会形成被称为盐的物质,如氯化钠(食盐)或硝酸钾(硝石),其晶体通常易碎且容易剥离。离子材料通常是晶体或多晶体。在实践中,可以通过固化熔融液体或从溶液中结晶出来,创建大的盐晶体。有些离子化合物可以非常硬,比如在许多宝石如红宝石和合成蓝宝石中发现的氧化铝。
Covalently bonded solids (sometimes called covalent network solids) are typically formed from one or more non-metals, such as carbon or silicon and oxygen, and are often very hard, rigid, and brittle. These are also very common, notable examples being diamond and quartz respectively. 共价键固体(有时被称为共价网络固体)通常由一个或多个非金属形成,如碳或硅和氧,这些固体通常非常硬,刚性强,易碎。这些也非常常见,著名的例子分别是钻石和石英。
Weak van der Waals forces also help hold together certain crystals, such as crystalline molecular solids, as well as the interlayer bonding in graphite. Substances such as fats, lipids and wax form molecular bonds because the large molecules do not pack as tightly as atomic bonds. This leads to crystals that are much softer and more easily pulled apart or broken. Common examples include chocolates, candles, or viruses. Water ice and dry ice are examples of other materials with molecular bonding.Polymer materials generally will form crystalline regions, but the lengths of the molecules usually prevent complete crystallization—and sometimes polymers are completely amorphous. 弱范德华力也有助于将某些晶体,如晶态分子固体,以及石墨的层间键合在一起。像脂肪、脂质和蜡这样的物质形成分子键,因为大分子不像原子键那样紧密排列。这导致晶体更软,更容易被拉开或破碎。常见的例子包括巧克力、蜡烛或病毒。水冰和干冰是具有分子键合的其他材料的例子。聚合物材料通常会形成晶态区域,但分子的长度通常阻止了完全结晶化——有时聚合物完全是无定形的。
Quasicrystals准晶体
The material holmium–magnesium–zinc (Ho–Mg–Zn) forms quasicrystals, which can take on the macroscopic shape of a pentagonal dodecahedron. Only quasicrystals can take this 5-fold symmetry. The edges are 2 mm long. 镁-锆-镝(Ho-Mg-Zn)材料可以形成准晶体,这种准晶体可以呈现出十二面五边形的宏观形状。只有准晶体才能呈现这种五重对称性。边长为2毫米。
A quasicrystal consists of arrays of atoms that are ordered but not strictly periodic. They have many attributes in common with ordinary crystals, such as displaying a discrete pattern in x-ray diffraction, and the ability to form shapes with smooth, flat faces. 准晶体由有序但非严格周期性的原子阵列组成。它们与普通晶体有许多共同的属性,如在X射线衍射中显示出离散的模式,以及形成具有光滑、平坦面的形状的能力。
Quasicrystals are most famous for their ability to show five-fold symmetry, which is impossible for an ordinary periodic crystal (see crystallographic restriction theorem). 准晶体最为人所知的特性是其能展现五重对称性,这对于普通的周期性晶体来说是不可能的(参见晶体学限制定理)。
The International Union of Crystallography has redefined the term "crystal" to include both ordinary periodic crystals and quasicrystals ("any solid having an essentially discrete diffraction diagram"). 国际晶体学联合会已经重新定义了“晶体”这个词,包括了普通的周期性晶体和准晶体(“任何具有基本离散衍射图的固体”)。
Quasicrystals, first discovered in 1982, are quite rare in practice. Only about 100 solids are known to form quasicrystals, compared to about 400,000 periodic crystals known in 2004. The 2011 Nobel Prize in Chemistry was awarded to Dan Shechtman for the discovery of quasicrystals. 准晶体,首次在1982年被发现,实际上是非常罕见的。只有大约100种固体被知道可以形成准晶体,相比之下,到2004年为止已知的周期性晶体大约有400,000种。2011年的诺贝尔化学奖颁给了Dan Shechtman,以表彰他对准晶体的发现。
Crystals can have certain special electrical, optical, and mechanical properties that glass and polycrystals normally cannot. These properties are related to the anisotropy of the crystal, i.e. the lack of rotational symmetry in its atomic arrangement. One such property is the piezoelectric effect, where a voltage across the crystal can shrink or stretch it. Another is birefringence, where a double image appears when looking through a crystal. Moreover, various properties of a crystal, including electrical conductivity, electrical permittivity, and Young's modulus, may be different in different directions in a crystal. For example, graphite crystals consist of a stack of sheets, and although each individual sheet is mechanically very strong, the sheets are rather loosely bound to each other. Therefore, the mechanical strength of the material is quite different depending on the direction of stress. 晶体可能具有一些特殊的电学、光学和机械性质,这些性质通常在玻璃和多晶体中无法出现。这些性质与晶体的各向异性有关,即其原子排列的旋转对称性的缺失。其中一个这样的性质是压电效应,即晶体中的电压可以使其收缩或伸展。另一个是双折射,即通过晶体观察时会出现双重影像。此外,晶体的各种性质,包括电导率、电容率和杨氏模量,可能在晶体的不同方向上有所不同。例如,石墨晶体由一堆片层组成,尽管每一片层在机械上都非常强大,但这些片层之间的结合相对较松。因此,材料的机械强度会根据应力的方向而有所不同。
Not all crystals have all of these properties. Conversely, these properties are not quite exclusive to crystals. They can appear in glasses or polycrystals that have been made anisotropic by working or stress—for example, stress-induced birefringence. 并非所有的晶体都具备这些性质。反过来说,这些性质并非完全只存在于晶体中。它们也可能出现在经过加工或应力处理而变得各向异性的玻璃或多晶体中,例如,应力诱导的双折射。
Crystallography is the science of measuring the crystal structure (in other words, the atomic arrangement) of a crystal. One widely used crystallography technique is X-ray diffraction. Large numbers of known crystal structures are stored in crystallographic databases. 晶体学是测量晶体结构(换句话说,原子排列)的科学。X射线衍射是一种广泛使用的晶体学技术。大量已知的晶体结构被储存在晶体学数据库中。
An apatite crystal sits front and center on cherry-red rhodochroite rhombs, purple fluorite cubes, quartz and a dusting of brass-yellow pyrite cubes. 一颗磷灰石晶体坐落在樱桃红色菱形菱锰矿、紫色氟石立方体、石英以及一层黄铜色黄铁矿立方体的尘埃上。
A specimen consisting of a bornite-coated chalcopyrite crystal nestled in a bed of clear quartz crystals and lustrous pyrite crystals. The bornite-coated crystal is up to 1.5 cm across. 这是一个由生铜矿覆盖的黄铜矿晶体构成的样本,它安静地躺在一床清晰的石英晶体和闪亮的黄铁矿晶体中。这个被生铜矿覆盖的晶体直径可达1.5厘米。
Crystallized sugar. Crystals on the right were grown from a sugar cube, while the left from a single seed crystal taken from the right. Red dye was added to the solution when growing the larger crystal, but, insoluble with the solid sugar, all but small traces were forced to precipitate out as it grew. 结晶糖。右侧的晶体是从糖块中生长出来的,而左侧的则是从右侧取出的单个种子晶体中生长出来的。在培养较大的晶体时,向溶液中添加了红色染料,但是,由于与固态糖不溶,除了少量痕迹被迫沉淀出来,其余的都随着晶体的生长而沉淀出来。
See also另请参阅
References参考资料
^κρύος, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library ^ κρύος,亨利·乔治·利德尔,罗伯特·斯科特,《希腊-英语词典》,在 Perseus 数字图书馆
^The surface science of metal oxides, by Victor E. Henrich, P. A. Cox, page 28, google books link 《金属氧化物的表面科学》,作者:Victor E. Henrich,P. A. Cox,第28页,谷歌书籍链接
^ One or more of the preceding sentences incorporates text from a publication now in the public domain: Flett, John Smith (1911). "Petrology". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 21 (11th ed.). Cambridge University Press. ^以上一句或多句内容引用自现已进入公共领域的出版物:Flett, John Smith (1911)。"岩石学"。在Chisholm, Hugh (ed.)。《大英百科全书》。第21卷(第11版)。剑桥大学出版社。
^ Yoshinori Furukawa, "Ice"; Matti Leppäranta, "Sea Ice"; D.P. Dobhal, "Glacier"; and other articles in Vijay P. Singh, Pratap Singh, and Umesh K. Haritashya, eds., Encyclopedia of Snow, Ice and Glaciers (Dordrecht, NE: Springer Science & Business Media, 2011). ISBN904812641X, 9789048126415 ^Yoshinori Furukawa的"冰";Matti Leppäranta的"海冰";D.P. Dobhal的"冰川";以及Vijay P. Singh, Pratap Singh和Umesh K. Haritashya编辑的《雪、冰和冰川百科全书》(Dordrecht, NE: Springer Science & Business Media, 2011)中的其他文章。ISBN 904812641X, 9789048126415。
^Nucleation of Water: From Fundamental Science to Atmospheric and Additional Applications by Ari Laaksonen, Jussi Malila -- Elsevier 2022 Page 239--240 ^"水的成核:从基础科学到大气及其他应用" 由 Ari Laaksonen, Jussi Malila 著 -- Elsevier 2022 页数239--240
^ Britain), Science Research Council (Great (1972). Report of the Council. H.M. Stationery Office. ^英国科学研究委员会(1972年)。委员会报告。H.M. 文具办公室。
^Encyclopedia of the Solar System by Tilman Spohn, Doris Breuer, Torrence V. Johnson -- Elsevier 2014 Page 632 ^《太阳系百科全书》由 Tilman Spohn,Doris Breuer,Torrence V. Johnson 编写 -- Elsevier 2014年,第632页。
^Science for Conservators, Volume 3: Adhesives and Coatings by Museum and Galleries Commission -- Museum and Galleries Commission 2005 Page 57 ^科学为保护者,第3卷:博物馆和画廊委员会的粘合剂和涂层 -- 博物馆和画廊委员会2005年第57页
