共查询到18条相似文献,搜索用时 78 毫秒
1.
利用高分辨电子显微技术(HREM)研究了钙稀土氟碳酸盐矿物晶体结构中的混层现象,在BmSn型规则混层矿物中发现了B5S4-3R和6R两种新多型,确定了它们的晶体结构类型,晶胞参数等,揭示出B5S4规则混层矿物不同多型体的超微结构特征,讨论了B5S4-6R多型晶体结构沿C方向的无序夹层和堆垛层错等晶体缺陷现象。 相似文献
2.
氟碳钙铈矿衍生多晶体的高分辨电镜研究吴秀玲,孟大维,杨光明,潘兆橹(中国地质大学测试中心,武汉430074)(中国科学院金属研究所固体原子像实验室,沈阳)氟碳钙铈矿(BS)是钙─铈氟碳酸盐系列矿物中的重要成员,具三方(R)对称,化学组成为Ce_2Ca... 相似文献
3.
钙—铈氟碳酸盐矿物中BmSn型新多型的发现及其微结构研究 总被引:5,自引:2,他引:5
利用Philips CM-12分析型透射电镜对四川昌北大型稀土矿床中钙铈氟碳酸盐矿物进行了研究。除证实氟碳钙铈矿(BS)存在3R和6R2种多型外,首次发现和研究了氟碳钙铈矿(BS)存在4H、12H、18R、24R、30R和36R6种新多型;伦琴矿(BS_2)1种6R新多型和B_2S新规则混层矿物2H、12R和24R3种中新多型。电子衍射和晶格象分析表明:该类矿物中众多新多型的产生,主要是由于矿物结构单元层沿(?)轴有序堆垛和[CO_3]的定向周期性变化所致。 相似文献
4.
5.
目的 :观察波形纤维蛋白转基因小鼠 (下称 VTg M)白内障晶状体的超微结构变化。方法 :用微注射法将鸡的波形纤维蛋白基因导入小鼠的受精卵中 ,获得 2 0只白内障小鼠。应用超薄切片透射电镜技术 ,观察 VTg M晶状体的超微结构改变。结果 :VTg M晶状体上皮细胞呈多层排列 ,细胞内有粗大的线粒体 ,晶状体皮质内有核细胞成团堆集 ,胞浆内有大量细胞器 ,特别是线粒体、溶酶体。晶体状纤维细胞排列紊乱 ,核伸长不完全。纤维的规则板层结构消失 ,出现大量的髓鞘样结构。结论 :外源性波形纤维蛋白的表达影响了晶状体上皮细胞的分化 ,使晶状体纤维细胞脱核 ,脱细胞器受抑制 ,晶状体纤维排列紊乱 ,导致白内障形成 相似文献
6.
本文简要论述了多层混压印制板工艺的实现方式,分析在微波电路中应用的优势和需要注意的问题,并着重对多层混压电路中微波参考地问题进行仿真和分析,提出两种有效地解决微波电路中参考地的共地方法,在经过实际验证后已经用于TR组件的集成设计. 相似文献
7.
8.
9.
10.
11.
12.
13.
P. Lamarre C. Fulk D. D’Orsogna E. Bellotti F. Smith P. LoVecchio M. B. Reine T. Parodos J. Marciniec S. P. Tobin J. Markunas 《Journal of Electronic Materials》2009,38(8):1746-1754
Dislocations are known to influence the electrical and optical properties of long-wavelength infrared (LWIR) HgCdTe detectors
and have been shown to limit the performance of arrays fabricated on heteroepitaxial substrates. To help better understand
dislocations in HgCdTe, a new method for preparing HgCdTe diagnostic epitaxial single-crystal samples by chemically removing
the supporting CdZnTe substrate has been developed. Using this new sample preparation technique, the behavior of misfit and
threading dislocations in HgCdTe epitaxial layers has been investigated by using a defect etch to reveal the dislocations
present in the thin HgCdTe films. In most cases etch pits on the surface of the film are spatially correlated with etch pits
on the bottom of the HgCdTe film. The small displacements of the related etch pits were used to obtain crystallographic information
concerning the paths followed by threading dislocations on allowed slip planes in the HgCdTe crystal. In addition, transmission
electron microscopy (TEM) is used to obtain more specific information regarding the Burgers vector of the dislocation. While
this new sample preparation technique is useful for studying dislocations in HgCdTe epitaxial layers, it can also be used
to study stress from ohmic contacts and passivation layers. The technique can be used for both liquid-phase epitaxy (LPE)-
and molecular-beam epitaxy (MBE)-grown HgCdTe on CdZnTe substrates. 相似文献
14.
15.
An ordered configuration between atoms is frequently observed in many alloys and complex ionic compounds, as the ordering structure is energetically more stable in terms of the lattice enthalpy. However, when the entropy effect becomes dominant with increasing temperature, the ordered configurational symmetry is subject to be thermally perturbed, resulting in a transition to a random distribution of atoms at elevated temperature. By comparing two Li(B′B″)2O4‐type spinel oxides having an identical space group and analogous compositions, it can be elucidated that the locally distinct chemical bonding characteristics, which are substantially covalent versus highly ionic, make a significant contribution to the formation of ordering. More importantly, such ordering structure is considerably robust without perturbation even at very high temperature near the melting point. The findings in this work suggest that the locally different bonding nature is one of the critical structure‐determining factors in complex oxides with multiple cations, emphasizing the significance of in‐depth understanding of the correlation of electronic configurations with the overall crystalline structure. 相似文献
16.
GaAs/InGaAs量子点应变场的TEM研究 总被引:1,自引:1,他引:0
运用透射电子显微术(TEM)对由分子束外延(MBE)制备的GaAs/InGaAs多层量子点样品进行观察和分析。利用对量子点周围应变场分布的模拟,定性解释了量子点形貌及其周围发现的凹陷区域。通过对量子点高分辨像显示的晶格错配和化学成分分析研究,解释了所研究样品中量子点尺寸逐层增大的现象。研究结果为量子点材料生长过程中应变场的控制提供了一些思路。 相似文献
17.
N. D. Zakharov Z. Liliental-Weber W. Swider J. Washburn A. S. Brown R. Metzger 《Journal of Electronic Materials》1993,22(12):1495-1498
The structure of InCaAs/InAlAs layers lattice matched to an InP substrate, grown on either (100) or on (110) with a 4° tilt
toward [111] at 500 and 300°C has been investigated by transmission electron microscopy. High perfection resulted for the
layers grown on [001] oriented substrates whereas growth on the near [110] substrates resulted in compositional nonuniformities,
macrosteps formation, and ordering of the group III elements. This difference in structural perfection between the two sets
of samples was also reflected in differences in electrical properties. 相似文献
18.
热解碳基C/C复合材料纤维--基体界面的精细结构 总被引:2,自引:0,他引:2
采用JEM-2010型高分辨透射电镜考察了热解碳基碳/碳复合材料的纤维-基体界面结构.实验发现,由化学气相渗透工艺所获得的热解碳并非仅与碳纤表面进行单一的机械粘合,也不是一个简单平面.其间存在具有感应结构的界面层,它是受碳纤维表面微晶感应而形成的由基本平行于表面且更为细小的微晶所组成的厚约数纳米至数十纳米的过渡层,碳纤维微晶越大,取向性越好,则界面层的厚度也越大,取向性也相应提高.由此可定性解释高模量碳纤维与热解碳粘合效果弱于高强碳纤维. 相似文献