X.Y. Pang Z.Q. Liu S.Q. Wang J.K. Shang
材料科学技术（英文）
Density functional theory was employed to investigate the bismuth segregation at Cu/Cu3Sn(010) interface. Five initial constructions were introduced by adopting the adhesion energy criterion. Among them, the so-called "between-Cu" construction in which the interface Cu atoms of Cu slab locate along Cu-Cu bond direction in Cu3Sn slab was found to be the most energy-favored at an adhesion energy of 1.96 J/m2. Based on this construction, five possible segregation sites were examined, and the most likely segregation site was determined with adhesion energy as low as 1.06 J/m2, which was almost half of the initial one. Comparing with other sites' adhesion energies, it was concluded that size effect took a large part in embrittlement. The analyses of atomic structure and electronic density revealed that the slabs shifted away from interfaces due to bismuth segregation, and the atoms around Bi atom were pressed away. This calculated work agreed qualitatively with reported experimental results.
关键词:
First-principles calculation
,
segregation
,
Bismuth
,
interface
,
SnBi solder.
王晓媛
,
嶋田隆広
,
北村隆行
无机材料学报
doi:10.3724/SP.J.1077.2014.13301
利用基于密度泛函理论的第一性原理的方法研究了超薄钛酸铅(PbTiO3)纳米管的铁电性及力电耦合特性.研究发现对于钛酸铅铁电纳米管结构,即使在其特征尺寸小于铁电薄膜的铁电临界尺寸时,依然存在自发极化.钛酸铅铁电纳米管结构不存在铁电临界尺寸.对纳米管力电耦合效应的研究发现,轴向应变作用会引起包括极化沿轴向方向的铁电相、顺电相和极化沿周向方向的铁电相在内的丰富的相转变.这种相的转变是由于轴向应力所导致的Pb-O共价键的变化所引起的.另一方面,研究了钛酸铅纳米管结构的机械强度,明确了在轴向拉伸和压缩作用下纳米管的临界载荷.
关键词:
铁电纳米管
,
钛酸铅
,
铁电临界尺寸
,
第一性原理计算
