Magnetic properties of Mo-doped TiO2 nanoparticles: A candidate for dilute magnetic semiconductors
Introduction
Dilute magnetic semiconductors (DMS) have garnered attention in the field of spintronics because they allow both spin and charge manipulation, indicating both charge and spin degree of freedom. However, room temperature FM with high Curie temperature is still an issue [1]. DMSs are formed by doping magnetic elements into semiconductor oxides. One such semiconductor oxide is TiO2 that has wide applications in various branches such as agriculture, the food industry, medicine, cosmetics, water treatment technologies, and semiconductors [2]. The crystallographic properties are also of interest because of TiO2 can exist in different phases [3]. Room temperature FM has been observed in both anatase and rutile phases of TiO2, and this magnetic behavior may be due to oxygen vacancies (VO) [4]. Moreover, many researchers have explored the magnetic, optical, and photocatalytic activities of transition elements-doped TiO2. Herein, we report Mo-doped TiO2 for their possible use as DMS. The photocatalytic nature of Mo-doped TiO2 and its application in batteries have been previously reported [5], [6], [7]; however, its magnetic properties have not been studied extensively. Z. Zou et al. [8] reported Mo and Mo co-doped TiO2 in the form of films and showed the existence of FM due to VO and doping mechanism, however, Curie temperature is not reported. Motivated by many studies on Mo doped TiO2 and Mo co-doped impurities for the possible ferromagnetism [9], [10], [11], [12], [13], we have prepared Mo-doped TiO2 nanoparticles as DMS material and studied its magnetic properties to understand the origin of FM in DMS.
Section snippets
Experimental
To prepare pure and Mo-doped TiO2 nanoparticles, 8.5275 g of Titanium tetra isopro-oxide (99%) was mixed with 15 ml of Isopropyl alcohol (98%) and stirred for about 1 h at 70 °C. An appropriate amount of Molybdenum Nitrate (99%) was added for Mo-doped TiO2 as 0.5% and 1% wt ratio to this mixture. This was followed by the drop-wise addition of 10 ml of acetic acid (99%) that was then heated in an autoclave for 12 h at 80 °C. The dried powders were collected and calcinated for 500 °C for 2 h. The
Results and discussion
Fig. 1a shows the experimental XRD patterns of pure and Mo-doped TiO2 nanoparticles. The figure clearly shows that the obtained peaks matched with the anatase phase of TiO2 (shown in vertical lines) [15], [16]. The additional phase is observed and indicated at peaks 27.32° in Fig. 1a; this phase is due to the MoO3 impurity phase and is insignificant due to its low intensity. Hence, the synthesized TiO2 nanoparticles are indexed predominantly in the anatase phase. The Debye-Scherrer formula
Conclusions
In summary, pure and Mo-doped TiO2 nanoparticles were synthesized by a chemical route with a particle size of about 26 nm. XRD suggested that TiO2 nanoparticles are crystallized in anatase phase with marginal impurity phase. The Mo-doped samples (0.5% and 1%) also show similar patterns that of pure TiO2 indicating the possibilities of Mo4 + replacing Ti4 + sites. The magnetic property of Mo-doped samples shows ferromagnetic nature whereas pure TiO2 is diamagnetic. The FM behaviour arises due to
CRediT authorship contribution statement
S. Ravi: Conceptualization, Methodology, Writing - original draft, Formal analysis. F. Winfred Shashikanth: Investigation, Data curation.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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