TY - JOUR
T1 - Effect of Ni doping on the microstructure and high Curie temperature ferromagnetism in sol-gel derived titania powders
AU - Bahadur, Nupur
AU - Pasricha, Renu
AU - Govind,
AU - Chand, Suresh
AU - Kotnala, Ravinder Kumar
PY - 2012/3/15
Y1 - 2012/3/15
N2 - Undoped, 0.05 and 0.5 mol% Ni-doped TiO 2 powders were prepared by a modified sol-gel route. The doping effects on the microstructure and magnetism for the powdered samples have been systematically investigated. Doping of Ni in TiO 2 inhibited rutile crystal growth. The probable reason for this is discussed on the basis of band calculation based analysis of electronic structures of 3d transition metal-doped TiO 2 and the energetic, transformation kinetics and phase stability of anatase over rutile as the function of particle size. Room temperature ferromagnetism (RTFM) with the saturation magnetization of 12 m emu g -1 and Curie temperature as high as 820 K is observed only in case of 0.05 mol% Ni:TiO 2 powdered sample, whereas undoped TiO 2 was diamagnetic and 0.5 mol% Ni:TiO 2 was paramagnetic in nature. The role of any magnetic impurity or any Ni metal in the origin of the RTFM has been ruled out by energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high resolution TEM (HRTEM) analysis, whereas magnetic force microscopy (MFM) established the presence of magnetic domains, supporting the intrinsic diluted magnetic semiconductor behavior. The observed ferromagnetism has been attributed to the spin ordering through exchange interaction between holes trapped in oxygen orbitals adjacent to Ni substitutional sites.
AB - Undoped, 0.05 and 0.5 mol% Ni-doped TiO 2 powders were prepared by a modified sol-gel route. The doping effects on the microstructure and magnetism for the powdered samples have been systematically investigated. Doping of Ni in TiO 2 inhibited rutile crystal growth. The probable reason for this is discussed on the basis of band calculation based analysis of electronic structures of 3d transition metal-doped TiO 2 and the energetic, transformation kinetics and phase stability of anatase over rutile as the function of particle size. Room temperature ferromagnetism (RTFM) with the saturation magnetization of 12 m emu g -1 and Curie temperature as high as 820 K is observed only in case of 0.05 mol% Ni:TiO 2 powdered sample, whereas undoped TiO 2 was diamagnetic and 0.5 mol% Ni:TiO 2 was paramagnetic in nature. The role of any magnetic impurity or any Ni metal in the origin of the RTFM has been ruled out by energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high resolution TEM (HRTEM) analysis, whereas magnetic force microscopy (MFM) established the presence of magnetic domains, supporting the intrinsic diluted magnetic semiconductor behavior. The observed ferromagnetism has been attributed to the spin ordering through exchange interaction between holes trapped in oxygen orbitals adjacent to Ni substitutional sites.
KW - Magnetic force microscopy (MFM)
KW - Magnetic properties
KW - Oxides
KW - Sol-gel growth
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U2 - 10.1016/j.matchemphys.2012.01.068
DO - 10.1016/j.matchemphys.2012.01.068
M3 - Article
AN - SCOPUS:84857789758
SN - 0254-0584
VL - 133
SP - 471
EP - 479
JO - Materials Chemistry and Physics
JF - Materials Chemistry and Physics
IS - 1
ER -