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shary_hua

木虫 (正式写手)

[交流] 纳米材料中常提到的Superlattice是什么意思!

纳米材料中常提到的Superlattice是什么意思!期盼各位给以解答!谢谢!
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meiniaike

铁杆木虫 (正式写手)

超晶格,指一种周期性阵列
2楼2008-01-09 17:04:17
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shary_hua

木虫 (正式写手)

感谢meiniaike 最短时间内给予的及时帮助!
还要继续麻烦了!
超晶格与通常所说的晶格有什么区别么?
3楼2008-01-09 17:21:20
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bachier

金虫 (职业作家)

呵呵

★ ★
NJUT_tiger(金币+2,VIP+0):好~~
超晶格,在纳米材料里,好像就是指纳米颗粒堆积成周期性排列的结构,这些结构和晶体内部,原子的排列有相似性
晶格,就是专门原子周期性排列构成的晶体的结构了
4楼2008-01-09 19:35:37
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bachier

金虫 (职业作家)

详细概念

A superlattice is a material with periodically alternating layers of several substances. Such structures possess periodicity both on the scale of each layer's crystal lattice and on the scale of the alternating layers. Semiconductor superlattices were first grown in the 70's and metallic superlattices in 1980.

Superlattices can be produced in a number of ways, but the most common are Molecular-beam epitaxy and Sputtering. With these methods lattices as thin as a few atomic layers can be produced. One nomenclature used to describe the produced superlattice is [Fe20V30]20 signifying a bi-layer consisting of 20Å of Iron (Fe) followed by 30Å of Vanadium (V), the whole structure repeated 20 times yielding a total thickness of 1000Å or 100nm.

The structural quality of the produced superlattices can be verified by means of X-ray diffraction which give rise to characteristic satellite peaks. The same applies to Neutron diffraction. Other effects of the alternating layering are: Giant magnetoresistance, tunable reflectivity for X-ray and Neutron mirrors, neutron spin polarization, and changes in the elastic and acoustic properties. Depending on the nature of components, a superlattice may be called magnetic, optical or semiconductor.

The motion of charge carriers in a superlattice is modified with respect to each individual lattice. This can lead to significant increase of carrier mobility (used in microwave devices) or special optical features (such as a semiconductor laser).
There also exists a class of quasiperiodic superlattices named after Fibonacci. The Fibonacci superlattices are usually studied as a single-dimensional model of quasicrystal, where either electron hopping transfer interactions or on-site energies take two values arranged in a Fibonacci sequence.
5楼2008-01-09 19:46:44
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bachier

金虫 (职业作家)

好好补

我自己也不明白,以前经常超晶格呵呵

是Superlattice不是Supperlattice,Superlattice和Supercell是有很大的区变的。Superlattice是一般是说两种材料按层状或间隔排起来的周期性结构,比如把A和B两种半导体做成半导体超晶格(ABABAB..........)。而Supercell是针最小的原胞或略大的晶包而言,对纯材料A而言,把它的原胞扩大nxmxl(n,m,l>1),这样得到晶格就是就是Supercell。如果你把两个材料A和B放在一起,排成层状周期性的ABAB或AA+BBB或其他的得到的晶格的最小周期性也是Supercell。所以在计算金属和半导体的所谓接触电势时,采用的是supercell不是superlattice。
6楼2008-01-09 19:50:40
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bachier

金虫 (职业作家)

按照这个概念来理解

做单分散纳米颗粒排列成的超晶格结构,是不严谨的,两种或者至少两种材料构成的
7楼2008-01-09 19:58:51
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temedx

专家顾问 (著名写手)

个人意见,仅供参考:
我觉得bachier说的很对,超晶格的提出就是多个材料互相叠加形成的。一般的所说超晶格其实应该是公度调制结构,也叫超结构(super structure),应该是晶体缺陷的周期性排列导致形成了长周期。
Everybodyissobusymindingotherppl'sbusiness,thattheyforgettofindtheirownhappiness.
8楼2008-01-10 11:41:10
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shiningx

荣誉版主 (知名作家)

小木虫模范教师

超晶格
请教一下学半导体的可能更有用
这个家伙很懒,什么也没有留下
9楼2008-01-10 15:29:09
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