THE FIRST-PRINCIPLES STUDY OF QUARTZ (100) SURFACE ADSORBED BY HYDROXYL
CALCIUM
Yu Xie, Yanbo Shang, Xingrong Zhang, Yunhai Zhang
Beijing General Research Institute of Mining and Metallurgy, Beijing 102628, China
ABSTRACT
The first-principles method was employed to conduct the research of hydroxyl calcium and hydroxyl
adsorption on hematite and quartz surfaces. The calculation results suggested that OH - preferred to the
active Fe sites on the hematite surface, whereas OH- adsorbed quartz by the weak hydrogen bond. Though
CaOH+ could easily adsorb on the hematite and quartz surfaces by the formation of Ca-O bond, the
covalence formed on the quartz surface was apparently stronger than that on the hematite surface, meaning
a stronger and more stable adsorption. CaOH+ adsorbed on quartz surface was mainly through the
interaction of O-2p and Ca-3d states. However, this interaction on hematite surface was weaker.
Figure 1 O-Si bond length before and after CaOH+ adsorption
2
O before adsorption
O-2s
O-2p
1
DOS/(electron·eV-1)
0
2 -8
-6
-4
-2
0
O after adsorption
2
O-2s
O-2p
1
0
2 -8
-6
-4
-2
0
Ca before adsorption
2
Ca-4s
Ca-3d
1
0
2 -8
-6
-4
-2
0
Ca after adsorption
2
Ca-4s
Ca-3d
1
0
-8
-6
-4
-2
0
2
Energy/eV
Figure 2 DOS of CaOH+ before and after adsorption on the hematite surface
KEYWORDS
First principles, Quartz, Hydroxyl calcium, Hematite