Solution In Bi0 Research Articles

Intrinsic and tunable ferromagnetism in Bi0.5Na0.5TiO3 through CaFeO3-\u03b4 modification

New (1-x)Bi0.5Na0.5TiO3 + xCaFeO3-δ solid solution compounds were fabricated using a sol–gel method. The CaFeO3-δ materials were mixed into host Bi0.5Na0.5TiO3 materials to form a solid solution that exhibited similar crystal symmetry to those of Bi0.5Na0.5TiO3 phases. The random distribution of Ca and Fe cations in the Bi0.5Na0.5TiO3 crystals resulted in a distorted structure. The optical band gaps decreased from 3.11 eV for the pure Bi0.5Na0.5TiO3 samples to 2.34 eV for the 9 mol% CaFeO3-δ-modified Bi0.5Na0.5TiO3 samples. Moreover, the Bi0.5Na0.5TiO3 samples exhibited weak photoluminescence because of the intrinsic defects and suppressed photoluminescence with increasing CaFeO3-δ concentration. Experimental and theoretical studies via density functional theory calculations showed that pure Bi0.5Na0.5TiO3 exhibited intrinsic ferromagnetism, which is associated with the possible presence of Bi, Na, and Ti vacancies and Ti3+-defect states. Further studies showed that such an induced magnetism by intrinsic defects can also be enhanced effectively with CaFeO3-δ addition. This study provides a basis for understanding the role of secondary phase as a solid solution in Bi0.5Na0.5TiO3 to facilitate the development of lead-free ferroelectric materials.

Structure, optical and magnetic properties of new Bi0.5Na0.5TiO3- SrMnO3\u2212\u03b4 solid solution materials

The new Bi0.5Na0.5TiO3-SrMnO3−δ solid solution materials were fabricated via sol–gel method. The random incorporation of Sr and Mn cations into host lattice of Bi0.5Na0.5TiO3 resulted in structural distortion and influenced on the reduction of the optical band gap from 3.07 eV to 1.81 eV for pure Bi0.5Na0.5TiO3 and 9 mol% SrMnO3−δ solid solution into Bi0.5Na0.5TiO3. The magnetic properties of Bi0.5Na0.5TiO3 materials at room temperature were tuned via compensation of diamagnetic material with weak-ferromagnetism to ferromagnetism with low SrMnO3−δ content and combination of paramagnetism/antiferromagnetism-like and ferromagnetism with higher SrMnO3−δ content solid solution in Bi0.5Na0.5TiO3. The tunable magnetic and optical properties of lead-free ferroelectric materials was promising for their application to green electronic devices.

Structural, optical, and magnetic properties of a new system of Bi(Mn0.5Ti0.5)O3-modified Bi0.5Na0.5TiO3 materials

Bi(Mn0.5Ti0.5)O3-modified Bi0.5Na0.5TiO3 materials were fabricated via the sol-gel method. X-ray diffraction and Raman scattering studies indicated that Bi(Mn0.5Ti0.5)O3 materials were a solid solution in host Bi0.5Na0.5TiO3 materials. The optical band gap energy was reduced from 3.06 eV for pure Bi0.5Na0.5TiO3 sample to 1.78 eV for 9 mol% Bi(Mn0.5Ti0.5)O3 solid solution in Bi0.5Na0.5TiO3 samples. The magnetic properties of Bi0.5Na0.5TiO3 materials were tuned in terms of Bi(Mn0.5Ti0.5)O3 concentration. The competition of weak ferromagnetism and diamagnetism was obtained in pure Bi0.5Na0.5TiO3 materials. The diamagnetic components of pure Bi0.5Na0.5TiO3 materials were suppressed and showed typical ferromagnetism for Bi(Mn0.5Ti0.5)O3-modified host Bi0.5Na0.5TiO3 materials with 3 mol% Bi(Mn0.5Ti0.5)O3 as a solid solution. A high Bi(Mn0.5Ti0.5)O3 concentration in a solid solution in host Bi0.5Na0.5TiO3 materials was favorable to paramagnetic and antiferromagnetic-like components. The optical band gap energy and tunable magnetic properties of Bi0.5Na0.5TiO3 materials were decreased by Bi(Mn0.5Ti0.5)O3 materials as a solid solution possibly because of diffusion and random incorporation in the host lattice of Bi0.5Na0.5TiO3 materials. Our work could be used as a basis for further developing multifunction materials by integrating ferromagnetism to lead-free ferroelectric materials for smart electronic applications.

Magnetic and optical properties of MgMnO3−-modified Bi0.5Na0.5TiO3 materials

Abstract The phase structural, optical and magnetic properties of a new (1 − x)Bi0.5Na0.5TiO3 + xMgMnO3−δ compound were investigated. The MgMnO3−δ -modified Bi0.5Na0.5TiO3 materials were fabricated using sol–gel method. Results of X-ray diffraction and Raman scattering indicated that the MgMnO3−δ materials were good solid solutions in the Bi0.5Na0.5TiO3 compound. The random distribution of Mg and Mn cations in the host lattice of Bi0.5Na0.5TiO3 materials reduced the optical band gap from 3.11 eV to 1.99 eV for 9 mol% MgMnO3−δ-modified Bi0.5Na0.5TiO3 materials. The complex magnetic behaviour in MgMnO3−δ-modified Bi0.5Na0.5TiO3 materials was obtained. The weak ferromagnetism vs. diamagnetism transformed to ferromagnetism vs. para/antiferromagnetic property depending on the concentration of MgMnO3−δ solid solution in Bi0.5Na0.5TiO3 samples. Our work can further contribute to the study of current injection ferromagnetic material in host lead-free ferroelectric materials for smart electronic device application.

Magnetic properties of (1 − x)Bi0.5Na0.5TiO3 + xMnTiO3 materials

Abstract MnTiO3-doped Bi0.5Na0.5TiO3 materials were fabricated by sol-gel technique. According to X-ray diffraction and Raman scattering analyses, MnTiO3 was suitable to be used as solid solution in Bi0.5Na0.5TiO3 but resulted in distorted structure. The optical band gaps decreased from 3.06 eV for pure Bi0.5Na0.5TiO3 to 1.69 eV for 9 mol% MnTiO3 solid solution in Bi0.5Na0.5TiO3. The magnetic properties of Bi0.5Na0.5TiO3 materials were tuned from ferromagnetism to combination of ferromagnetism and paramagnetic-like property with varying MnTiO3 concentration. The reduction of the optical band gap and the tunable magnetic properties of Bi0.5Na0.5TiO3 materials were due to the random distribution of Mn cation in the host lattice as a function of MnTiO3 amounts. This work provides a new trend of selecting dopants to induce ferromagnetism in lead-free ferroelectric materials.

Structural, optical, and magnetic properties of SrFeO 3-δ -modified Bi 0.5 Na 0.5 TiO 3 materials

Abstract SrFeO3-δ-modified Bi0.5Na0.5TiO3 materials were fabricated by a sol–gel method. SrFeO3-δ materials existed as a well solid solution in Bi0.5Na0.5TiO3 materials, resulting in the random distribution of Sr and Fe cations into the lattice of the host. The impurities of Sr and Fe cations preferred to substitute at the A-site and B-site in Bi0.5Na0.5TiO3 materials, respectively. These cations distorted the structure of the host materials due to differences in the radius of the cations of impurity and the host. The modified materials showed reduced optical band gap and strongly induced ferromagnetism at room temperature. This work presents a new method for integrating room-temperature ferromagnetism in lead-free ferroelectric materials to overcome the limitations of single transition metals as dopants.

Room-temperature ferromagnetism in Fe-based perovskite solid solution in lead-free ferroelectric Bi0.5Na0.5TiO3 materials

The integration of ferromagnetism in lead-free ferroelectric materials is important to fabricate smart materials for electronic devices. In this work, (1 − x)Bi0.5Na0.5TiO3 + xMgFeO3-δ materials (x = 0–9 mol%) were prepared through sol–gel method. X-ray diffraction characterization indicated that MgFeO3-δ materials existed as a well solid solution in lead-free ferroelectric Bi0.5Na0.5TiO3 materials. The rhombohedral structure of Bi0.5Na0.5TiO3 materials was distorted due to the random distribution of Mg and Fe cations into the host lattice. The reduced optical band gap and the induced room-temperature ferromagnetism were due to the spin splitting of transition metal substitution at the B-site of perovskite Bi0.5Na0.5TiO3 and the modification by A-site co-substitution. This work elucidates the role of secondary phase as solid solution in Bi0.5Na0.5TiO3 material for development of lead-free multiferroelectric materials.

Structural, Optical, and Magnetic Properties of Lead-Free Ferroelectric Bi0.5K0.5TiO3 Solid Solution with BiFeO3 Materials

A solid solution of Bi0.5K0.5TiO3-BiFeO3 was fabricated by a sol–gel technique. The pure Bi0.5K0.5TO3 samples exhibited weak room-temperature ferromagnetism. The room-temperature ferromagnetism was observed in BiFeO3 solid solution in Bi0.5K0.5TiO3. The optical band gap of Bi0.5K0.5TiO3 was reduced from 3.22 eV to 1.39 eV with the increase in the amount of BiFeO3 solid solution. The room-temperature ferromagnetism and band gap reduction were attributed to the diffusion of BiFeO3 into Bi0.5K0.5TiO3 to form a solid solution. Our work provided a simple method of realizing room-temperature ferromagnetism in lead-free ferroelectric materials.

Dielectric properties of lead-free solid solution of Bi0.487Na0.487La0.017TiO3 and BaTiO3

Bismuth sodium titanate (Bi0.5Na0.5TiO3; BNT) is one of the most preferred materials for the preparation of lead-free ceramics; however its dielectric property is lower than that of lead-based materials. Thus, the substitution of A and B-site cations is considered to be one of the best solutions in order to improve both the dielectric and piezoelectric properties. In this study, lead-free ceramics from bismuth sodium lanthanum titanate (Bi0.487Na0.487La0.017TiO3; BNLT) and barium titanate (BaTiO3; BT) systems were prepared by a modified two-step mixed oxide method. BT powder was added to BNLT powder with the desired compositions of (1 − x)BNLT–xBT, where x = 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10. It was found that the addition of BT in the BNLT improved the electrical properties of ceramics. Phase transition of rhombohedral to tetragonal structure was significantly dependent on the amount of BT added. It was also found that the change in crystal structure affected the ferroelectric property of the ceramics where the transition from ferroelectric to antiferroelectric started from the samples with x ≥ 0.06 mol% and higher. This may be useful in terms of using these materials in the desired applications.