First-Principles Calculations of Energy Band for Wurtzite ZnO under Uniaxial Loading along [0001] Direction

2014 ◽  
Vol 633-634 ◽  
pp. 324-328
Author(s):  
Li Xin Li ◽  
Jun Liang Zhao ◽  
Xue Mao Guan

First-principles calculations are carried out to analyze the variation of the energy gap and the absolute value of the crystal-field splitting energy of wurtzite zinc oxide under uniaxial loading along [0001] direction. The uniaxial loading in [0001] direction is predicted to be more effective to adjust the energy gap than applying the hydrostatic pressure, without changing the direct energy-gap nature. The top of the valence band is sensitive to the uniaxial stress, and the absolute value of the crystal-field splitting energy reaches the minimum when the uniaxial stress is about 2 GPa. The variation in electronic properties originates mainly from the relatively lower density of the valence electrons inc-axis direction.

2018 ◽  
Vol 5 (2) ◽  
pp. 171376 ◽  
Author(s):  
Yan-ping Zhang ◽  
Hai-feng Liu ◽  
Hai-long Hu ◽  
Rui-shi Xie ◽  
Guo-hua Ma ◽  
...  

LaCoO 3 epitaxial films were grown on (100), (110) and (111) oriented LaAlO 3 substrates by the polymer-assisted deposition method. Crystal structure measurement and cross-section observation indicate that all the LaCoO 3 films are epitaxially grown in accordance with the orientation of LaAlO 3 substrates, with biaxial compressive strain in the ab plane. Owing to the different strain directions of CoO 6 octahedron, the mean Co–O bond length increases by different amounts in (100), (110) and (111) oriented films compared with that of bulk LaCoO 3 , and the (100) oriented LaCoO 3 has the largest increase. Photocatalytic degradation of methyl orange indicates that the order of photocatalytic activity of the three oriented films is (100) > (111) > (110). Combined with analysis of electronic nature and band structure for LaCoO 3 films, it is found that the change of the photocatalytic activity is closely related to the crystal field splitting energy of Co 3+ and Co–O binding energy. The increase in the mean Co–O bond length will decrease the crystal field splitting energy of Co 3+ and Co–O binding energy and further reduce the value of band gap energy, thus improving the photocatalytic activity. This may also provide a clue for expanding the visible-light-induced photocatalytic application of LaCoO 3 .


2019 ◽  
Vol 100 (15) ◽  
Author(s):  
G. Krizman ◽  
T. Schumann ◽  
S. Tchoumakov ◽  
B. A. Assaf ◽  
S. Stemmer ◽  
...  

1967 ◽  
Vol 19 (25) ◽  
pp. 1417-1420 ◽  
Author(s):  
Walter N. Hardy ◽  
James R. Gaines

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