The pressure dependence of the intraimpurity absorption and the charge transfer process of ZnS:Ni and ZnSe:Ni

Abstract

The absorption specva of ZnS:Ni and ZnSe:Ni were measured at 100 K under hydrostatic pressure up to 10 GPa. Two kinds of optical transition were investigated: (i) the d-d transifions between crystal field levels of Ni2+ in the tetmhedrd field of the host lattice and (ii) a charge transfer band that occurs when an electron is Vansferred from the valence band to the Niz+ ion. The pressure dependence of the crystal field parameter Dy and of the Racah panmeter B were determined and B revised assignment of the d d transitions was obtained. The charge tnnsfer c m be considered as a deep-acceptor tmsition. In this w e the Ni acceptor level may be used JS an energy reference. which enabled us to determine the hydrostatic deformation potentid of the valence band.

Defect structure of Co2+ center in rhombohedral BaTiO3

“…For BaTiO 3 :Co 2+ , no optical spectral data were reported, we estimate reasonably the above parameters as follows: Considering that for 3d n cluster Dq / R À5 is approximately valid [18][19][20][21] and that the Racah parameters B and C decreases slightly with decreasing metal-ligand distance R 0 [22], from the optical spectra of similar (CoO 6 ) 10À clusters in MgO:Co 2+ [23] and the distance R 0 = 2.105 Å [24] and 2.002 Å [13] for MgO and BaTiO 3 (rhombohedral phase), respectively, we can estimate for BaTiO 3 :Co 2+ B % 770 cm À1 ; C % 3930 cm À1 ; Dq % À1208 cm À1 ð6Þ…”

Optical and magnetic properties of transition-metal ions in tetrahedral and octahedral compounds

“…V 3+ and Ti 2+ , which are usually regarded as the typical ions with d 2 configuration, have been extensively studied by many physicists and chemists [18][19][20][21][22][23][24][25][26][27][28][29]. The optical absorption and EPR spectra of V 3+ and Ti 2+ in tetrahedral crystals have been reported [21][22][23][24].…”

Energy levels of thed*8electron andd*2hole system

“…Then the t 2 6Ϫm e 4Ϫn hole configuration can be considered as a complementary configuration of the t 2 m e n electron configuration in the t 2 6 e 4 closed shell and has the same terms as the t 2 m e n configuration. 4,5 We can obtain the following terms in the d* 8 configuration from the d* 2 configuration:…”

“…The optical properties of the transition-metal ions in II-VI and III-V semiconductor materials, for example, CdTe:V, 1 ZnTe:V, 2 GaAs:Cr, 3 ZnS:Ni, 4 and ZnSe:Ni, 4 have been extensively studied. The classical crystal field theory has been widely used in the calculation of the energy levels of the transition-metal impurities in the ionic crystal.…”