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Screw Dislocation Generation by Inclusions in Molecular Crystals
Crystal Growth & Design ( IF 3.2 ) Pub Date : 2017-12-20 00:00:00 , DOI: 10.1021/acs.cgd.7b01292
Xiaodi Zhong 1 , Alexander G. Shtukenberg 1 , Theodore Hueckel 1 , Bart Kahr 1 , Michael D. Ward 1
Affiliation  

Dislocations in crystals affect material properties and are essential for crystal growth near equilibrium, yet their genesis in the absence of external or internal stresses is unresolved. X-ray topography has revealed microscopic inclusions as dislocation sources, but the real-time creation of a dislocation by a particulate inclusion has not been reported. In situ atomic force microscopy (AFM) was used herein to visualize dislocation generation in an l-cystine crystal by a cube-like hematite particle embedded in, and slightly inclined with respect to, the l-cystine {0001} surface. The particle produced two pairs of heterochiral screw dislocations with opposing Burgers vectors. After overgrowth of the particle, dissolution in undersaturated solutions revealed the dislocations once again until the detachment of the particle exposed a flat basal plane devoid of dislocations, thereby corroborating the essential role of the particle. Hematite particles with their flat faces parallel or at high angle to the surface, as well as spherical poly(styrene) particles, did not produce dislocations, suggesting that shape and orientation of the particle with respect to the step train advancing across the growing crystal surface are critical features for dislocation generation.

中文翻译:

分子晶体中夹杂物产生的螺丝位错

晶体中的位错会影响材料的性能,并且对于晶体接近平衡时的生长必不可少,但是它们在没有外部或内部应力的情况下的成因尚未解决。X射线形貌已揭示出微观夹杂物是位错源,但尚未报道通过微粒夹杂物实时产生位错的情况。本文中使用原位原子力显微镜(AFM)来可视化通过嵌入并相对于l稍微倾斜的立方状赤铁矿粒子在l-胱氨酸晶体中产生位错-胱氨酸{0001}表面。粒子产生了两对带有相反Burgers向量的异手性螺丝位错。在颗粒过度生长之后,在不饱和溶液中的溶解再次显示出位错,直到颗粒的分离暴露出没有位错的平坦基面,从而证实了颗粒的基本作用。平面与表面平行或成高角度的赤铁矿颗粒以及球形聚苯乙烯颗粒均不会产生位错,这表明颗粒相对于跨整个生长晶体表面前进的阶梯序列的形状和方向是位错产生的关键特征。
更新日期:2017-12-20
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