Sol-Gel Synthesis, Magnetic and Optical Properties of Co2+:Nd3+::2:1 molar ratio doped in SiO2

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Bibliographische Detailangaben
Zeitschriftentitel:	JOURNAL OF ADVANCES IN CHEMISTRY
Personen und Körperschaften:	Das, Bidhu Bhusan, Rao, Ruppa Govinda
In:	JOURNAL OF ADVANCES IN CHEMISTRY, 11, 2015, 3, S. 3367-3374
Format:	E-Article
Sprache:	Unbestimmt
veröffentlicht:	CIRWOLRD

Details
Zusammenfassung:	<jats:p>Synthesis of Co2+:Nd3+::2:1 molar ratio doped SiO2 with Co2+ ions concentrations viz. 0.0004, 0.001, 0.002, 0.003, 0.004 moles in S1-S5, respectively are performed by sol-gel method. Observed values of the densities and the concentrations of the Co2+ ions in S1-S5 are found to be 2.26, 2.29, 2.37, 3.44, 2.49 g/cm3, and ~ 1020 ions/g, respectively. Powder XRD results show the formation of amorphous SiO2 phase in the samples. DTA-TGA/DTG traces in the range 27-700 ˚C show no characteristic event in the samples. The IR peak in the range 412-418 cm-1 is ascribed to the asymmetric mode of the octahedral [NdO6/2]3- units. The peak around 440 cm-1 in S1-S5 is due to the ν2-symmetric bending mode of the tetrahedral [SiO4/2]4- units. The weak IR peak ~ 670 cm-1 is due to the ν1-mode of the tetrahedral [CoO4/2]4- units. The calculated values of the magnetic susceptibility from the observed magnetic moments data at 300 K are found to be ~10-6 emu/gG in S1-S5 which show the weak paramagnetic nature of the materials. The EMR lineshapes recorded at 6, 50, 77, and 300 K are very broad, isotropic and smeared out with only two detectable characteristic peaks. The giso-value ~ 2.3 is due to the doped Co2+(3d7) ions in tetrahedral coordinations, while the giso-value ~ 2.01 is due to the doped Nd3+(4f3) ions in distorted octahedral coordinations. The lineshapes only at 6 K are distinct, while at higher temperatures these peaks are severely smeared out. The optical absorption broad band at ~750 nm (13262 cm-1) is assigned to 4I9/2 ® 4F7/2 + 4S3/2 transitions in optically active Nd3+(4f3) ions, and the peak ~ 520 nm (19230 cm-1) is attributed to 4A2g ® 4T1g(P) transitions in Co2+ (S=3/2, 3d7) ions in tetrahedral coordinations.</jats:p>
Umfang:	3367-3374
ISSN:	2321-807X
DOI:	10.24297/jac.v11i3.864