Influence of N Doping on the Electronic Structure and Absorption Spectrum of Ca2SiO4: Eu2+ Phosphor

doi:10.15541/jim20160201

Abstract

Abstract:

The electronic structure and absorption spectrum of Ca₂SiO₄: Eu²⁺ was studied by using density functional theory. It is found that N atoms substituted provide many states around the Femi level, which leads to narrow optical band gap and interband transition originating from N2p to the Eu4f. In the N-doped Ca₂SiO₄: Eu²⁺ phosphor, Eu²⁺ ions experience a strong nephelauxetic effect and crystal field due to the coordinating nitrogen ions around the activated centers, which results in Eu4f and 5d states splitting. Thus, the red-shift of the absorption spectrum and high absorption band in the wavelength of 220-470 nm takes place for the N-doped Ca₂SiO₄: Eu²⁺ phosphor.

Key words: N-impurity, silicate phosphor, light emitting diodes (LEDs), density functional theory (DFT)

CLC Number:

O482

CHEN Hai-Tao, HUANG Xue-Fei, HUANG Wei-Gang. Influence of N Doping on the Electronic Structure and Absorption Spectrum of Ca₂SiO₄: Eu²⁺ Phosphor[J]. Journal of Inorganic Materials, 2017, 32(4): 443-448.

Figures/Tables 8

Fig. 1 Structure of the super-cell of Ca2SiO4: Eu2+ without (a) and with (b) substitution of N atoms for O atoms

Table1 Atomic populations of Ca2SiO4: Eu2+

Case	Eu site	Element	s	p	d	f	Total
1	Ca(1)	O	1.88	5.31	0	0	7.19
		Si	0.68	1.50	0	0	2.18
		Ca	2.18	6.00	0.34	0	8.52
		Eu	2.17	6.24	0.67	7	16.07
2	Ca(2)	O	1.86	5.23	0	0	7.09
		Si	0.70	1.47	0	0	2.17
		Ca	2.14	6.00	0.60	0	8.74
		Eu	2.14	6.13	0.60	7	15.87

Fig. 2 The band structure and TDOS of Ca2SiO4: Eu2+ without (a) and with (b) substitution of N atoms for O atoms for the case

Fig. 3 The band structure and TDOS of Ca2SiO4: Eu2+ without (a) and with (b) substitution of N atoms for O atoms for the case 2

Fig. 4 The PDOS of Ca2SiO4: Eu2+ without (a) and with (b) substitution of N atoms for O atoms for the case 1

Fig. 5 The PDOS of Ca2SiO4: Eu2+ without (a) and with (b) substitution of N atoms for O atoms for the case 2

Fig. 6 The absorption spectra of Ca2SiO4: Eu2+ without (a) and with (b) substitution of N atoms for O atoms for the case 1

Fig. 7 The absorption spectra of Ca2SiO4: Eu2+ without (a) and with (b) substitution of N atoms for O atoms for the case 2

References 17

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Influence of N Doping on the Electronic Structure and Absorption Spectrum of Ca₂SiO₄: Eu²⁺ Phosphor

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