Weak Ferromagnetic Properties Research Articles

Dual Eu3+ and Er3+ doping in ZnO nanoporous 2D frameworks for tuning photocatalytic activity, linear and non-linear optical response

Recent days, the greater attention of research materials are focusing on the porous nano frame structure due to their distinctive properties and high photocatalytic activity. The porous defective materials revealed a significant role in numerous research fields like sensors, catalysts, energy production, magnetic memory storage, bio medical etc. In our work, pure ZnO and 4f shell shielded rare earth metals doped ZnO metal oxide nanomaterials attributed in the photocatalytic dye degradation, non-linear optical and magnetic properties. We were synthesized pure ZnO and ZnO0.1–2xEuxErxHMT0.1–2x (2x = 0.025,0.05,0.075, 0.010 wt%) nanoparticles using a straightforward hydrothermal route. The hexagonal wurtzite structure of ZnO and Eu:Er-doped ZnO (Eu:Er@ZnO) exhibited by PXRD, and the optical bandgap (Eg) range from 3.14 eV to 3.18 eV was determined by Tauc relation (αhγ)2 = 0. The porous nanoplate morphology of as-synthesized materials revealed by HR-SEM and HR-TEM techniques. All synthesized materials exposed weak ferromagnetic property nature by VSM studies. Among all the synthesized materials, the 0.0025 wt% Eu:Er@ZnO nanoparticles exhibited porous nanoplate structures capable of catalyzing the breakdown of reactive black 5 (RB5) dye, achieving a photocatalytic activity of 93.2 % after 65 min of UV light exposure. The dopant concentration significantly influenced this photocatalytic activity, with lower concentrations showing enhanced performance, particularly in acidic conditions. Moreover, all synthesized porous nano-plate materials followed pseudo-first-order kinetics. Additionally, the Z-scan technique was employed to assess the nonlinear optical properties of the synthesized materials using Q-switched nanosecond Nd laser pulses at 532 nm wavelength. The open-aperture Z-scan revealed reverse saturable absorption (RSA) in all samples. The Eu:Er@ZnO porous nano-plates exhibited promising nonlinear absorption characteristics, with a higher nonlinear absorption coefficient ranging from 5.21 to 7.84 × 10−11 m/W and a lower optical limiting threshold between 0.87 and 0.95 × 1012 W/m2.

Microstructures, Magnetic Properties and Specific Absorption Rate of Polymer-Modified Bismuth Ferrite Nanoparticles

Bismuth ferrite nanoparticles were successfully synthesized by the co-precipitation method and modified by polyethylene glycol (PEG) 4000. X-ray diffraction patterns showed a sillenite structure of bismuth ferrite (Bi25FeO40) with a crystallite size of 35.0 nm and the new phase appeared after surface modification. The new phase was Bi2Fe4O9. Crystallite size increased after surface modification of nanoparticles with PEG. The highest increase of crystallite size after surface modification with PEG was 40.1 nm. Transmission electron microscopy images showed that samples before and after surface modification were polycrystalline and still agglomerated. Spectra of Fourier transform infrared showed the presence of C-O stretching at 1080 cm-1 and C-H bending vibration at 1342 cm-1 in the bismuth ferrite/PEG sample, which did not appear in bismuth ferrite sample. The magnetic measurement indicated the weak ferromagnetic properties of the samples. Saturation magnetization did not appear after a maximum external magnetic field (15 kOe) was applied. The maximum magnetization of nanoparticles was 0.5 emu/g and tended to decrease to 0.2 emu/g after surface modification with PEG. Optical properties analysis showed a shift in the maximum absorption peak of bismuth ferrite nanoparticles towards a lower wavelength (blue shift) after surface modification of the nanoparticles. The specific absorption rate (SAR) value of nanoparticles increased by increasing an alternating magnetic field (AMF) strength. The SAR values of bismuth ferrite nanoparticles were 48.8, 61.4, and 84.4 mW/g and decreased to 32.0, 45.2, and 83.3 mW/g after surface modification at the AMF strength of 150, 200, and 250 Oe, respectively.

Microstructural, optical, and magnetic properties and specific absorption rate of bismuth ferrite/SiO2 nanoparticles

In this study, the microstructural, optical, and magnetic properties and specific absorption rate (SAR) of bismuth ferrite/SiO2 nanoparticles were successfully investigated. The coprecipitation method was used to synthesize the nanoparticles. X-ray diffraction patterns showed the presence of sillenite-type Bi25FeO40 with a body-centered cubic structure. The crystallite size of Bi25FeO40 was 35.0 nm, which increased to 41.5 nm after SiO2 encapsulation. Transmission electron microscopy images confirmed that all samples were polycrystalline. The presence of Si–O–Si (siloxane) stretching at 1089 cm−1 in Fourier transform infrared spectra confirmed the encapsulation of SiO2. Magnetic measurements at room temperature indicated weak ferromagnetic properties of the samples. The coercivity of the bismuth ferrite nanoparticles was 78 Oe, which increased after SiO2 encapsulation. In contrast, their maximum magnetization, 0.54 emu g−1, reduced after SiO2 encapsulation. The determined bandgap energy of the bismuth ferrite nanoparticles was approximately 2.1 eV, which increased to 2.7 eV after SiO2 encapsulation. The effect of SiO2 encapsulation on the SAR of the samples was investigated using a calorimetric method. The SAR values of the bismuth ferrite nanoparticles were 49, 61, and 84 mW g−1 under alternating magnetic field (AMF) strengths of 150, 200, and 250 Oe, respectively, which decreased after SiO2 encapsulation. The maximum magnetization and the AMF strength influenced the SAR of the nanoparticles. The results showed that SiO2 has a significant effect in determining the microstructural, optical, and magnetic properties and SAR of the nanoparticles.

Atomic scale insights on the growth of BiFeO3 nanoparticles

This study provides new insights on the formation of the nanocrystallites of phase pure BiFeO3 prepared using sol–gel method with tartaric acid as the fuel as comprehended based on the local structure and magnetic hyperfine fields at Fe sites using Mossbauer spectroscopy. Important steps involved in the growth of the nanocrystallites of BiFeO3 in the sol–gel reaction are elucidated in a detailed manner in this study for the first time. Three important stages with the second stage marked by the formation of as high as 75% of nanocrystallites of BiFeO3 occurring over a narrow calcination temperature interval 700–723 K have been deduced in this study. Variation of hyperfine parameters with calcination temperature of the dried precursor gel leading to an increase in the mean size of crystallites of BiFeO3 has been deduced. The nanoparticles of BiFeO3 are deduced to exhibit weak ferromagnetic property in addition to being strongly ferroelectric based on the magnetization and P-E loop studies. Consequently an appreciable magneto electric coupling effect in terms of significant changes in P-E loop variation with the application of external magnetic field is elucidated in this study, which is comprehended based on the defects associated with BiFeO3 nanoparticles.

Structural, morphological, and magnetic properties of NiF2 assisted growth of Ni-multi walled carbon nanotubes

This paper reports the synthesis and magnetic properties of NiF2 assisted growth of multi-walled carbon nanotubes. Ni-Multi-Walled Carbon Nanotubes (Ni-MWCNT) were synthesized by catalytic decomposition of Xylene (C8H10) and NiF2 (as a precursor for metallic Ni) using Chemical Vapor Deposition (CVD). The presence of graphitic carbon crystallization and a dominant metallic nickel phase is confirmed by XRD and Raman analysis. The in-situ formation of Ni nanoparticles from NiF2 precursor successfully aids the growth of Ni-MWCNTs. The diameter of synthesized Ni-MWCNT was measured to be around 100 nm. Ni-MWCNT exhibit a weak ferromagnetic property due to the presence of metallic Ni residues.

Methylene blue photodegradation using as‐synthesized CeO2 nanoparticles

AbstractCerium oxide (CeO2) nanoparticles via solution combustion technique using Ce(NO3)3 as an oxidizer and benzoic acid as fuel were prepared at two different temperatures (500 and 600°C). The as‐synthesized CeO2 nanoparticles were characterized using FT‐IR, PL, BET, XRD, VSM, and TEM techniques. The results of FT‐IR and XRD techniques show that cerium oxide nanoparticles have been successfully synthesized. The absence of other peaks in the XRD pattern indicates that there are no impurities in these compounds. TEM images also confirm the synthesis of nanoparticles smaller than 20 nm. VSM results of CeO2 nanoparticles show weak ferromagnetic properties. Furthermore, the as‐synthesized CeO2 nanoparticles were used for the photocatalytic degradation of methylene blue (MB). The effect of various parameters such as irradiation time, amount of catalyst dosage, initial MB concentration, and solution pH was investigated. The results show that the best conditions for photocatalytic removal are pH solution of 10, 0.02 g of catalyst dose, initial MB concentration of 40 ppm, and UV irradiation time of 90 min. Therefore, the as‐synthesized CeO2 nanoparticles have a good performance as a catalyst and can be used for other organic dyes.

The Influence of Annealing Temperature on the Structure and Magnetic Properties of Nanocrystalline BiFeO3 Prepared by Sol\u2013Gel Method

In this work, BiFeO3 powders were synthesized by a sol–gel method. The influence of annealing temperature on the structure and magnetic properties of the samples has been discussed. X-ray diffraction studies showed that the purest phase was formed in the temperature range of 400 °C to 550 °C and the samples annealed at a temperature below 550 °C were of nanocrystalline character. Mössbauer spectroscopy and magnetization measurements were used as complementary methods to investigate the magnetic state of the samples. In particular, the appearance of weak ferromagnetic properties, significant growth of magnetization, and spin-glass-like behavior were observed along with the drop of average grain size. Mössbauer spectra were fitted by the model assuming cycloidal modulation of spins arrangement and properties of the spin cycloid were determined and analyzed. Most importantly, it was proved that the spin cycloid does not disappear even in the case of the samples with a particle size well below the cycloid modulation period λ = 62 nm. Furthermore, the cycloid becomes more anharmonic as the grain size decreases. The possible origination of weak ferromagnetism of the nanocrystalline samples has also been discussed.

Microwave assisted synthesis and characterization of Fe3+-O-Fe3+ sublattice magnetic moment influencing ferromagnetism exhibited erbium orthoferrite sublattice (ErFeO3) perovskite nanopowders

In this work, we report the systematic experimental synthesis and characterization of rare earth Erbium metal incorporated orthoferrite (EOF) nanoparticles (NPs) via microwave-assisted technique. The instrument micro-oven was used to induce exothermic heating inside the sample which causes the formation of ErFeO3 nano-crystallites. The unit cell structure of Erbium substituted orthoferrite nano-crystallite is studied by using experimental results and computational techniques by simulating the orthorhombic phase. Crystal lattice structure and its direct and reciprocal parameters are analysed by performing the Rietveld refinement process on the Powder X-ray diffraction pattern (P-XRD) data which confirms the fabricated unit cell structure belongs to the orthorhombic-cubic phase (spacegroup: Pbnm) with slightly induced distortion in bond distance between atoms. From FTIR fingerprint region of metal oxides, the vibrational frequency of harmonically oscillating Er-O groups in ErFeO3 unit cells was observed at (414 and 420 cm−1) and this value is consistent with the theoretical vibrational frequencies of Er-O (424.0410 and 426.5122 cm−1) calculated based on the Hooks law by considering the Er-O groups as a harmonic system. Similarly, the observed and calculated vibrational frequencies of Fe-O groups are found at (536, 570 and 576 cm−1) and (530.2621, 531.4341 and 549.7296 cm-1) respectively. The band gap of the ErFeO3 is found to be 2.1 eV. Weak Ferromagnetic property is observed in MH plot for the synthesized EOF nanoparticles due to formation of lower bond angle of Fe3+-O-Fe3+ sublattice with 140.5782° and 147.6881°. SEM image of ErFeO3 is confirmed the spherically distributed nano-crystallites with size ranging from 62 to 166 nm. In this research, Match (v3) and VESTA open-source programs are used for the Rietveld refinement process and to calculate bond distance between atoms in the unit cell.

Room‐temperature ferromagnetic organic magnets derived from fluoro‐graphite via facile halide exchange

AbstractRoom‐temperature ferromagnetic organic magnet is developed via a facile halide exchange process using fluoro‐graphite (FG) as a starting material. Structural and chemical analysis reveals that heterogeneous C–F bond cleavage in the defect sites of FG is essentially related to the formation of ferromagnetic hydroxyl‐graphene (HG). Pyrolysis of FG in a polar solvent with iodine ions induces a formation of metastable C–I bond and subsequent replacement of the I sites with the hydroxyl groups. Specifically, defective sites can be formed in FG due to nucleophile attack where the OH groups can be easily generated. As a result, the FG can be transformed into the HG with a network of sp2‐conjugated carbon motifs in a sp3‐based graphene matrix. Hence, the paramagnetic centers in the π‐electron system of FG can be transformed to the long‐range ordered ferromagnetic centers in the sp2‐conjugated system of HG. Electron paramagnetic resonance data demonstrate the weak ferromagnetic property of HG stable at room temperature.

Microwave Absorption Properties of Monovalent Doped La<sub>0.85</sub>Ag<sub>0.15</sub>MnO<sub>3</sub> Manganites Prepared by Solid State Method

The microwave absorption properties of La0.85Ag0.15MnO3 prepared by solid state method was investigated. Analysis of X-ray diffraction data using a refinement technique confirmed the rhombohedral structure of the samples. The microstructure of the sample characterised from field emission scanning electron microscope micrographs showed irregular grain shapes with grain sizes ranging from 800 to 1500 nm. M-H curves revealed the weak ferromagnetic properties of the sample at room temperature. The real and imaginary parts of permittivity and permeability as well as microwave reflection loss were measured by a vector network analyser in the 8–18 GHz frequency range. The La0.85Ag0.15MnO3 sample showed a minimum reflection loss of –57.2 dB at 16.41 GHz, with a –10dB bandwidth (corresponding to reflection loss below –10 dB, or 90% absorption) of 2.67 GHz. The microwave absorption of La­­­­0.85Ag0.15MnO3 mainly arises from the conduction loss and domain wall motion which contributed to dielectric loss and magnetic loss, respectively.

Ultrasonically sprayed cobalt oxide thin films: Enhancing of some physical properties by nickel doping

In this study, the effect of Ni doping (3, 6, 9 at%) on structural, optical, electrical and magnetic properties of Co3O4 films was reported. Films were grown at 300 ± 5 °C substrate temperature via ultrasonic spray pyrolysis (USP) technique. The structural analyses showed that undoped and Ni (3%) doped films exhibit an amorphous structure. Ni doping at higher ratios caused the films to have improved crystallinity. Optical band gap values the films were found to be between 2.03 and 2.08 eV with an additional sub-band corresponding to energies varying between 1.35 and 1.46 eV. The electrical conductivity values of the films increased significantly depending on the Ni doping. The hysteresis curves of the films showed that the films have weak ferromagnetic properties. Ni doping significantly improved the structural and electrical properties of Co3O4 films making them suitable materials for technological applications.

Unusual isosymmetric order–disorder phase transition in a new perovskite-type dimethylhydrazinium manganese formate exhibiting weak ferromagnetism and photoluminescence properties

We report the synthesis, thermal, structural, dielectric, magnetic and optical properties of a novel metal–organic framework templated by the large 1,1-dimethylhydrazinium cation. We analyse the steric hindrance-related properties.

Synthesis of Cu–Ti–Al-based intermetallic alloy. Structural phase analysis and electrophysical properties

For the first time, an intermetallic alloy based on the Heusler phase – Cu2TiAl – was obtained by self-propagating high-temperature synthesis (SHS) in the Cu–Ti–Al reaction mixture. The frontal combustion modes of green mixture compositions and phase formation processes during synthesis were studied. The products obtained were studied by X-ray diffraction analysis including high-temperature diffractometry with stage heating up to 900 K, scanning electron microscopy, differential thermal analysis (DTA), and some physical properties were studied. Also, electrophysical and magnetic measurements were carried out for the obtained alloy. The results of X-ray analysis and SEM using energy-dispersive analysis (EDA) showed that the Heusler phase content in the synthesized product is at least 82 %. The product also contains copper (Cu9Al4) and titanium (Ti3Al2) aluminides. The temperature dependence of the synthesized product electrical resistivity was measured for a wide temperature range of 90–1000 K, which was 0.3 μmm at T = 300 K. The metallic type of the conductivity for the samples obtained and the abnormal behavior of the electrical resistance temperature curve in the region of Т = 770÷790 K were revealed. Thermal analysis was used to measure the melting point of the synthesized product and to reveal additional heat effects at Т = 788, 848 and 1248 К associated with possible phase transitions in the Cu2TiAl intermetallic compound. A possible mechanism of phase transitions is considered in accordance with the Cu–Ti–Al system phase diagram. Magnetic measurements results showed that intermetallic samples obtained by the SHS method feature by weak ferromagnetic properties with residual magnetization of 0.069 A·m2/kg.

Structural, Optical and Magnetic Properties of Dy-doped In2O3 Nanoparticles

(In1−xDyx)2O3 (x = 0, 0.05, 0.10) nanoparticles with a particle size of 15–22 nm were obtained by an auto-combustion method. The powder x-ray diffraction (XRD), Raman and x-ray absorption near edge spectral (XANES) analysis revealed a cubic bixbyite structure (space group Ia-3). The presence of Dy3+ ions in the In2O3 host lattice was confirmed from XPS data. The high-resolution transition electron microscopic (HRTEM) and XANES revealed the single phase (solid solution) nature of the nanoparticles. The optical band gap was found to increase from 3.57 eV to 3.64 eV by doping Dy into the In2O3 lattice. Photoluminescence spectra shows emission in the yellow region probably due to oxygen related vacancies. A weak ferromagnetic property was seen for Dy-doped In2O3 at room temperature, while pure In2O3 is diamagnetic. It seems that Dy:In2O3 is not a suitable␣system to consider for dilute magnetic semiconductors in spintronic devices.

Structure of Pb(Fe2/3W1/3)O3 single crystals with partial cation order

Despite intensive studies on the complex perovskite Pb(Fe2/3W1/3)O3 (PFWO) relaxor, understanding the exact nature of its multifunctional properties has remained a challenge for decades. In this work we report a comprehensive structural study of the PFWO single crystals using a combination of synchrotron X-ray diffraction and high-resolution electron microscopy. The set of {h + ½, k + ½, l + ½} superlattice reflections was observed for the first time based on single-crystal synchrotron X-ray experiments (100–450 K) and transmission electron microscopy investigations, which indicates some kind of B-cation ordering in PFWO which had been thought to be totally disordered. It was found that (1) the crystal structure of PFWO should be described by a partly ordered cubic perovskite (i.e. Fm − 3m), (2) the weak ferromagnetic properties and excess magnetic moment of PFWO can be understood based on non-random distribution of Fe cations between the 4a and 4b sites, and (3) the Pb displacement disorder is present in this material and the cations are probably displaced along the <100> directions. The X-ray diffraction results of this investigation show that partial cation ordering indeed exists in PFWO, which makes it necessary to revisit the generally accepted interpretations of the results obtained up to date. In agreement with X-ray diffraction study the main results of TEM study include: (1) a long range order that can be described with the Fm − 3m symmetry is reliably detected, (2) the coherence length of that long range order is in the order of 1–2 nm and (3) no remarkable chemical inhomogeneity is found in the tested PFWO crystal, excluding the possibility of a compositional ordering arising from substitutional defects in the perovskite structure.

Effect of polyvinylpyrrolidone on the catalytic properties of Pd/γ-Fe2O3 in phenylacetylene hydrogenation

Maghemite nanoparticles modified with polyvinylpyrrolidone were synthesized using the chemical co-precipitation method. Palladium ions have then been immobilized on the PVP/γ-Fe2O3 magnetic support. The Pd-PVP/γ-Fe2O3 catalyst obtained was characterized using X-ray diffraction, thermogravimetry coupled with differential scanning calorimetry and quadrupole mass spectrometry, scanning electron microscopy combined with energy dispersive X-ray analysis, transmission electron microscopy, nitrogen adsorption–desorption and vibrating sample magnetometry. Morphology, microstructure, particle sizes and textural properties of the Pd-PVP/γ-Fe2O3 were compared with those of the unmodified Pd/γ-Fe2O3 catalyst, synthesized using the same method. The polymer has affected the size of γ-Fe2O3 nanoparticles and their agglomeration, forming compact microstructure with decreased mesopores (4.5 nm). Palladium nanoparticles with size of 3–5 nm were found both on the surface of the PVP/γ-Fe2O3 particles (6–10 nm) and inside the pores formed by them. The Pd-PVP/γ-Fe2O3 has demonstrated improved catalytic properties in phenylacetylene hydrogenation under mild conditions of 40 °C and 0.1 MPa, compared to Pd/γ-Fe2O3 and similar catalysts prepared using polyethylene glycol and pectin. The hydrogenation rate of C–C triple bond on Pd-PVP/γ-Fe2O3 achieved 2.8 × 10–6 mol s−1 and selectivity to styrene was 92%. The catalyst showed weak ferromagnetic and soft magnetic properties (MS = 51 emu g−1, Mr = 5.4 emu g−1, and HC = 71 Oe) and, therefore, can be easily recovered with an external magnet and reused for at least 11 runs without significant degradation in the catalytic activity.

Proximity effect in [Nb(1.5 nm)/Fe(x)]10/Nb(50 nm) superconductor/ferromagnet heterostructures.

We have investigated the structural, magnetic and superconduction properties of [Nb(1.5 nm)/Fe(x)]10 superlattices deposited on a thick Nb(50 nm) layer. Our investigation showed that the Nb(50 nm) layer grows epitaxially at 800 °C on the Al2O3(1−102) substrate. Samples grown at this condition possess a high residual resistivity ratio of 15–20. By using neutron reflectometry we show that Fe/Nb superlattices with x < 4 nm form a depth-modulated FeNb alloy with concentration of iron varying between 60% and 90%. This alloy has weak ferromagnetic properties. The proximity of this weak ferromagnetic layer to a thick superconductor leads to an intermediate phase that is characterized by a suppressed but still finite resistance of structure in a temperature interval of about 1 K below the superconducting transition of thick Nb. By increasing the thickness of the Fe layer to x = 4 nm the intermediate phase disappears. We attribute the intermediate state to proximity induced non-homogeneous superconductivity in the structure.

Coexistence of Weak Ferromagnetism and Paramagnetism in T’-Pr&lt;sub&gt;2-&lt;/sub&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;Ce&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;CuO&lt;sub&gt;4+α-δ &lt;/sub&gt;Nanoparticles

The coexistence of ferromagnetism and paramagnetism of T’-Pr2-xCexCuO4+α-δ (T’-PCCO) nanoparticles with x = 0, and 0.10 have been studied intensively in the normal state. All samples were synthesized by a chemically dissolved method using HNO3 as a dissolving agent. The calcination process was performed at 1000°C for 15 h in air and followed by reduction annealing at 700°C in argon atmosphere for 10 h. All samples were first characterized by an x-ray diffraction (XRD) measureemnts followed by Rietveld and Maximum Entropy Method (MEM) analyseis. The result confirms the Ce-dependence and reduction annealing effect on the electron density at around the Cu site. The magnetic characterization was performed by using vibration sample magnetometer (VSM) indicating weak ferromagnetic properties at x = 0 and dominant paramagnetic properties at x = 0.10 at room temperature. Moreover, the weak ferromagnetic feature seems to remain after the annealing process. This signifies the coexist of weak ferromagnetism and paramagnetism at the normal state due to a number of oxygen vacancies in the crystal structure.

Co-precipitation synthesis of mesoporous maghemite for catalysis application

Mesoporous magnetic nanoparticles (MNPs) were synthesized using the chemical co-precipitation method. The structure, morphology and magnetic properties of the MNPs were examined by X-ray diffraction (XRD), Mossbauer spectroscopy (MS), Brunauer–Emmett–Teller (BET) method, Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometer (VSM). The results of XRD and MS indicated that the MNPs were composed of γ-Fe2O3. TEM microphotography showed that the magnetic material was an aggregate of small spherical particles with a size of 6–12 nm. According to the BET data, the agglomeration of individual maghemite nanoparticles lead to formation of a complex mesoporous structure with the specific surface area of 88.3 m2 g−1. The average pore diameter was 5–7 nm, which correlates with the γ-Fe2O3 particles size. The VSM measurement (MS = 40.54 emu g−1, Mr = 5.27 emu g−1, HC = 88 Oe) indicated that the γ-Fe2O3 exhibited weak ferromagnetic and soft magnetic properties confirming the agglomeration of the small γ-Fe2O3 nanoparticles. The synthesized mesoporous maghemite showed excellent ability to absorb polymer protected colloidal palladium particles (Pd-PAM). The magnetic properties of MNPs were not significantly changed after modification with Pd-PAM. The resulting catalyst of Pd-PAM/MNPs showed activity (WC≡C = 3.3 × 10–6 mol s−1) and selectivity (93%) in the hydrogenation of phenylacetylene under mild conditions of 40 °C and 0.1 MPa. The Pd-PAM/MNPs catalyst can be easily recovered with an external magnet and reused for at least seven runs without significant degradation in the catalytic activity and selectivity.

Structural, Optical, and Magnetic Properties of the New (1-x)Bi0.5Na0.5TiO3 + xMgCoO3-δ Solid Solution System

A new (1-x)Bi0.5Na0.5TiO3 + xMgCoO3-δ solid solution system was synthesized using the simple sol–gel method. The structure that was investigated via X-ray diffraction and Raman scattering analysis indicated that the MgCoO3-δ materials were highly soluble into the host Bi0.5Na0.5TiO3 crystals. The random incorporation of Mg and Co cations into the host crystal of the Bi0.5Na0.5TiO3 materials reduced the optical band gap energy and induced a complex magnetic behavior as a function of MgCoO3−δ concentration solute in the host matrix. The optical band gap energy values decreased from 3.05 eV for pure Bi0.5Na0.5TiO3 materials to 2.22 eV with 9 mol% MgCoO3-δ solution for the Bi0.5Na0.5TiO3 compounds. A weak ferromagnetic property with strongly induced diamagnetism was obtained at room temperature for the pure Bi0.5Na0.5TiO3 materials, whereas ferromagnetic properties were observed for the MgCoO3-δ-modified Bi0.5Na0.5TiO3 compounds. The addition of paramagnetic and/or antiferromagnetic-like behavior was obtained for the MgCoO3-δ solid solution with over 5 mol% in the host Bi0.5Na0.5TiO3 materials. This work contributes to the current understanding of the interaction of transition metal cations in the host crystal ABO3 perovskite of lead-free ferroelectric materials due to the co-modification of A and B sites.