Magnetic and nonlinear optical properties of BaTiO3 nanoparticles

Abstract

In our earlier studies the BaTiO3 samples were processed at higher temperatures like 1000oC and explained the observed magnetism in it. It is found that the charge transfer effects are playing crucial role in explaining the observed ferromagnetism in it. In the present work the samples were processed at lower temperatures like 650oC-800oC. The carrier densities in these particles were estimated to be ∼ 1019-1020/cm3 range. The band gap is in the range of 2.53eV to 3.2eV. It is observed that magnetization increased with band gap narrowing. The higher band gap narrowed particles exhibited increased magnetization with a higher carrier density of 1.23×1020/cm3 near to the Mott critical density. This hint the exchange interactions between the carriers play a dominant role in deciding the magnetic properties of these particles. The increase in charge carrier density in this undoped BaTiO3 is because of oxygen defects only. The oxygen vacancy will introduce electrons in the system and hence more charge carriers means more oxygen defects in the system and increases the exchange interactions between Ti3+, Ti4+, hence high magnetic moment. The coercivity is increased from 23 nm to 31 nm and then decreased again for higher particle size of 54 nm. These particles do not show photoluminescence property and hence it hints the absence of uniformly distributed distorted [TiO5]-[TiO6] clusters formation and charge transfer between them. Whereas these charge transfer effects are vital in explaining the observed magnetism in high temperature processed samples. Thus the variation of magnetic properties like magnetization, coercivity with band gap narrowing, particle size and charge carrier density reveals the super paramagnetic nature of BaTiO3 nanoparticles. The nonlinear optical coefficients extracted from Z-scan studies suggest that these are potential candidates for optical imaging and signal processing applications.

Reduction of Ln2Ti2O7 Layered Perovskites: A Survey of the Anionic Lattice, Electronic Features, and Potentials

“…Indeed, for both compounds, M ( H ) shows the opening of a small hysteresis loop at all temperatures, accompanied by a remnant moment that slightly increases with cooling. This non-zero magnetization called FM nano hereafter was already observed and discussed for nanometric BaTiO 3 and PbTiO 3 with amplitudes similar to those of the title compounds. In agreement with theoretical calculations, it was assigned to extrinsic surficial oxygen vacancies leading to Ti 3+ or Ti 2+ FM interactions.…”

“…It is also noteworthy that external atoms at the interlayer edges are not concerned by reduction, see Figure 6a. This nonzero magnetization called FM nano hereafter was already observed and discussed for nanometric BaTiO 3 35 and PbTiO 3 36 with similar amplitudes as in the title compounds. In agreement with theoretical calculations 37 , it was assigned to extrinsic surficial oxygen vacancies leading to Ti 3+ or Ti 2+ FM interactions.…”

“…26 This type of irregular intergrowth of the layers has also been reported after the reduction La 3 Ni 2 O 7−x into La 3 Ni 2 O 6. 35 . 27 Here again, the observation of n = 5 octahedral thick blocks (La 5 Ti 5 O 17 with intrinsic Ti 3+ distribution) under more reducing conditions comforts the defected state of LTO-CaH 2 .…”

Femtosecond nonlinear absorption and optical limiting action in nanoplatelet CuFe2O4-decorated rGO nanocomposites

“…Linear absorption is a predominant mechanism in the resonant region, while it is multi-photon processes in the non-resonant region. To understand the nonlinear absorption process of the prepared sample, the acquired data were fitted using the standard relation for open aperture normalized transmittance [49]. It is to be noted that the match found between numerical and experimental data just ascertains the reliability of the experiment performed and it does not confirm or indicate the occurrence of 2PA, to be genuine or sequential two-step ESA.…”

Enhanced Third Order Nonlinear Optical Properties of Methyl Orange Dye Doped Potassium Penta Borate Octa Hydrate (MOPPB) Single Crystals Using CW Diode Laser for Optical Limiting Applications

“…Then the graph was drawn between the transmittance and position of the sample. In general, nonlinear absorption arises due to various phenomenon like saturable absorption (SA), reverse saturable absorption (RSA) that originates from two photon absorption (2PA), multiphoton absorption (MPA), excited state absorption(ESA) or free carrier absorption (FCA)[36]. Here, valley-like OA curve (Fig.…”