Ion Substitution Research Articles

Sodium alginate synergises with copper ion deposition on LDH surface to enhance the fire resistance of waterborne epoxy coatings

Layered double hydroxide (LDH) possesses the effect of interlayer barrier and dilute the concentration of flammable gases due to its unique lamellar structure, which enables it to perform excellent flame retardancy in both gas and condensed phases. In this paper, the abundant hydroxyl and carboxyl groups on the surface of sodium alginate (SA) were utilized to confer excellent hydrophilicity to LDH. Meanwhile, through ion substitution at the carboxyl site of sodium alginate, thus introducing Cu to catalysis charring into LDH@SA for the synthesis of a novel organometallic ion flame retardant (LSCu). Combination of flame retardants with intumescent fireproofing coatings to prepare composite coatings and test them for fire performance. The large panel test indicated that when the LSCu content was 4 %, the backside temperature of the steel panel dropped to 174.7°C, and the char layer surface remained intact, without any holes or cracks. In the furnace test, the composite coating had the highest expansion height (15.6 mm) and expansion rate (13.28 %) with uniform expansion. SEM illustrated that the char layer of the composite coating had a honeycomb structure, which enhanced the adsorption of heat and smoke. In addition, the composite coating retained the highest residual char content (28.1 %), which had to do with the synergistic effect between LDH and Cu complexes. Furthermore, through analyzing the residual char, it was demonstrated that the formation of metal oxides by LSCu at elevated temperatures improved the sustained barrier performance of the char layer.

Mn‐doped Pb(In1/2Nb1/2)O3‐Pb(Mg1/3Nb2/3)O3‐PbTiO3 relaxor ferroelectric ceramics for high‐power piezoelectric applications

AbstractAchieving comprehensive improvement in both piezoelectric coefficient (d33) and mechanical quality factor (Qm) has become a key issue in the research of high‐power piezoelectric ceramics. Here, we focused on Mn‐doped Pb(In1/2Nb1/2)O3‐Pb(Sc1/2Nb1/2)O3‐PbTiO3 (PIN‐PSN‐PT) relaxor ferroelectric ceramics, where Mn‐doping is employed to enhance Qm. The effects of doping concentration and PT content on phase structure, ferroelectric, dielectric, and electromechanical properties were systematically studied. The well radius matching between Mn ions and B‐site ions facilitates the ion substitution and significantly increases the concentration of oxygen vacancies, thereby enhancing the domain wall pinning effect. A significantly weakened mutual constraint relationship between d33 and Qm is observed in the 2 mol% Mn‐doped PIN‐PSN‐PT ceramics with tetragonal phase, which exhibits Qm exceeding 3000 while maintaining d33 higher than 320 pC/N and Curie temperature higher than 300°C, leading to the vibration velocity over 1.15 m/s. Rayleigh analysis reveals the higher intrinsic piezoelectric response in high PT components compared to that in low PT components, which was thought to be the origin for the weakened mutual constraint relationship between d33 and Qm in tetragonal Mn‐doped PIN‐PSN‐PT ceramics.

Structural analysis, relaxor-ferroelectric behavior and optical properties of Mn3+-doped CaBi3NdTi4O15 synthesized via hydrothermal technique

In this study, the synthesis of the Aurivillius Ca1-xBi3+xNdTi4-xMnxO15 (CBNTMx), where x is 0, 0.2, and 0.4, was carried out using the hydrothermal technique. The X-ray diffraction (XRD) data showed that the polar orthorhombic structure in space group of A21am was adopted by all powder samples. All samples possessed anisotropic plate-like particle shapes, and the particle size increased with increase in x value. The phase transition temperature (Tm) is decreased by the ionic substitution owing to the decrease in orthorhombic distortion reflected by the reduction of orthorhombicity. Relaxor-ferroelectric behavior was observed for CBNTM0.4 because of its strong frequency dispersion, while CBNTM0 and CBNTM0.2 only showed a diffused-phase transition (DPT) indicated by the broad dielectric constant at the transition temperature (Tm). The electrical conductivity exhibited an enhancement at higher x value since the ionic substitution with acceptor Mn3+ ions introduced the charge carrier in the lattice. Similarly, the reduction of optical band gap energy from 3.43 eV for the parent CBNTM0 to 2.75 eV and 2.71 eV for CBNTM0.2 and CBNTM0.4, respectively, was described as the contribution of the lower energy level of Mn 3d orbital than that of Ti 3d in the conduction band and also the less distorted structure.

Effect of substituted cobalt–chromium–iron oxides’ dissolution kinetics in oxidizing formulation on decontamination process

Removing radioactive corrosion products from Cr-containing iron oxides require a multi-step and multi-cycle decontamination process. The present article brings out the effect of divalent metal ion substitution on the release rate of chromium in the oxidative pre-treatment step. The non-stoichiometric cobalt chromium ferrites were synthesized, characterized and effect of Zn2+/Ni2+ substitution on the dissolution behavior was probed. The dissolution rates decreased with increasing the degree of inclusion and showed minima at ~ 0.4–0.6 atom% which is explained on the basis of lattice structure. It is concluded that the dissolution kinetics of native nickel–chromium ferrites in reactors increases with metal ion inclusion.

Synthesis and characterization of lithium fluoride-doped hydroxyapatite by aqueous precipitation

Hydroxyapatite is an essential material for bone and dental composition, widely used in biomaterials due to its biocompatibility and bioactivity. Its crystalline structure, similar to human bone, facilitates integration with biological tissues, promoting bone and dental regeneration. Applications include implants, orthopedic coatings, and bone grafts. The aim of this work was to synthesize hydroxyapatite with different percentages of lithium fluoride by aqueous precipitation. The produced powders were sintered at 1100 °C, and their properties were characterized by XRD, FTIR, and SEM. The results indicated the presence of fluorapatite and calcium oxide phases in the hydroxyapatite with lithium fluoride, with ion substitution occurring, while samples without LiF addition revealed the presence of hydroxyapatite and calcium oxide phases. SEM images showed that the samples with LiF addition exhibited morphological anisotropy, while pure hydroxyapatite samples showed equiaxed grains. The addition of LiF reduced the porosity of the samples after sintering. FTIR results indicated that fluoride ions replaced the hydroxyl groups originally present in the pure hydroxyapatite structure.

Study of the effect of Sr2+ ions substitution on the dielectric behaviour of BaCr2O4 chromites synthesized by solution combustion method

Study of the effect of Sr2+ ions substitution on the dielectric behaviour of BaCr2O4 chromites synthesized by solution combustion method

Manipulating and investigating the room-temperature magnetic memory phenomenon: The impact of rare-earth ion doping on nickel oxide nanoparticles

This study investigates the relationship between point defect density and magnetic properties in nickel oxide (NiO) nanoparticles (NPs). Specifically, we explore the effects of 0.5 % trivalent rare-earth ion (RE3+: Ce3+, Pr3+, Nd3+, Sm3+, and Dy3+) doping on NiO NPs, considering the influence of RE3+ ionic radius on structural modulation and magnetic properties. Our findings reveal important trends: increased microstrain (0.08 %–0.17 %) and decreased crystalline size (36–17 nm) with increasing ionic radius (r = 0.91 to 1.01 Å), along with a preference for growth along the (1 1 1) plane over (2 0 0). Additionally, multivalent point defects increase with the increase of ionic radius. Substituting Ni2+ site with RE3+ ion promotes nearest-neighbor weak ferromagnetic interaction over next-nearest-neighbor strong antiferromagnetic (AF) interaction. This leads to a redshift of two magnons (2 M) frequency by 50 cm−1 and enhanced room temperature (RT) magnetization (0.23–0.43 emu/g) with increasing ionic radius. Ce-doped NiO (r = 1.01 Å) shows the smallest crystalline size (17 nm), maximum 2 M redshift, and enhanced RT magnetization (0.43 emu/g) based on interacting bound magnetic polaron model. Ce-, Pr-, Nd-, and Sm-doped NiO NPs exhibit RT magnetic memory effects, while Dy-doped NiO NPs (r = 0.912 Å) display AF properties. Our analysis provides valuable insights for designing RT magnetic memory materials with tailored properties through suitable RE3+ ion substitutions.

In Ukrainian

The paper discusses the results of saponite research from the Tashkiv deposit of Ukraine. X-ray structural analysis proved the necessity of preliminary cleaning of saponites from mineral impurities. The study of the morphology, nanoprofile and topography of the surface of saponite by the methods of SEM-microscopy and Atomic Force Microscopy revealed that the mineral is represented by aggregates of nano- and microparticles of a pyramidal shape. Its characteristic feature is the heterogeneity of isomorphic substitutions of ions in the tetrahedral and octahedral sheets of the structural elementary package. According to X-ray fluorescence analysis, saponite contains a significant amount of Fe3+, which isomorphically replaces magnesium Mg2+ and, accordingly, is located mastly in the octahedral sheet of the structural package with a charge from +0.37 to +0.35. The number and mechanism of isomorphic substitutions determine the presence of a total negative charge of the crystal lattice (from –0.38 to –0.3), the value of which ensures intensive interaction with water molecules of the interpacket space with the formation of surface OH groups. Accordingly, both acidic and alkaline Lewis and Brønsted centers are present on the surface with a predominance of acidic ones, so the acidity function is 5.82, and the point of zero proton charge is pH = 5.5. During dispersion in water, a part of the alkaline centers of the side surface are transformed into Brønsted acid centers as a result of their protonation, which causes an increase in the pH of the dispersion medium to pH = 8–8.6. Accordingly, the isoionic state is reached at pH = 7.5. The difference in pH values characterizing the isoionic state of the surface and the point of zero net proton charge (PZNPC) indicates the presence of weak acid-alkaline centers on the surface. The study of the adsorption of acid-alkaline dyes showed the adsorption of alkaline (pK = 1¸3) and acid (pK = 7¸14) dyes on saponites. The latter is significantly reduced due to the preliminary hydration of the solid surface - mainly the lateral edges of the particles. Acidic dyes are not adsorbed from a dispersion medium with pH < 5.5 (PZNPC), and basic dyes are adsorbed at pH > 5,5( PZNPC).

Unlocking the high-capacity operation of P2-type cathode through bifunctional spectator ions substitution

The high specific capacity of the P2-type cathode endowed by the synergistic cation and anion redox makes it one of the most promising cathode materials for sodium-ion batteries (NIBs). However, the structural rearrangement and the irreversible oxygen release under highly desodiated states engender stability issues upon high-capacity operation. Herein, we show specifically how the structural degradation of the P2-type cathode is effectively stabilized by the substitution of bifunctional spectator ions. The rational incorporation of Ti and Si ions triggers the “pillar effect” and “inductive effect”, which eliminates the P2-O2/P2-P2′ structural evolution and mitigates the irreversible oxygen oxidation. Benefited from the highly reversible anion redox, the obtained Na0·67Li0·21Mn0·59Si0·01Ti0·19O2 represents a high reversible capacity of 220 mAh g−1 at 0.1C (20 mA g−1) within a Na-metal half-cell. Ex-situ XRD reveals a solid solution reaction without the formation of additional phases among the charge/discharge process, thus favoring stable cycling performance for up to 200 cycles at 2.5C (with a capacity retention rate of 88 %). This work shows, not only the specific strategies for improving the electrochemical performance of cathode materials, but also offers insights into the intrinsic mechanisms underlying the performance enhancement achieved through spectator ion substitution.

Effect of Physicochemical Surface Properties of Silicon-Substituted Hydroxyapatite on Angiogenesis.

Synthetic hydroxyapatite (HA) is a widely studied bioceramic for bone tissue engineering (BTE) due to its similarity to the mineral component of bone. As bone mineral contains various ionic substitutions that play a crucial role in bone metabolism, the bioactivity of HA can be improved by adding small amounts of physiologically relevant ions into its crystal structure, with silicate-substituted HA (Si-HA) showing particularly promising results. Nevertheless, it remains unclear how distinct material characteristics influence the bioactivity due to the intertwined nature of surface properties. A coculture methodology was optimized and applied for in vitro quantification of the biological response. Initially, HA and Si-HA samples were produced and characterized. To compare the bioactivity of the samples, a method was developed to measure interactions in an increasingly complex environment, first including fibronectin (FN) adsorption and subsequently cell adhesion in mono and coculture using primary human osteoblasts (hOBs) and human dermal microvascular endothelial cells (HDMECs), with and without FN precoating. An experimental set-up was designed to assess to what extent different surface features of the samples contribute to the induced biological response. An 8-nm gold sputter coating was applied to eradicate the electrochemical differences and polishing and abrading was used to reduce the differences in surface topographies. Overall, 1.25 wt% Si-HA exhibited most nanoscale variations in surface potential. In terms of bioactivity, 1.25 wt% Si-HA samples induced the highest osteoblast attachment and vessel formation. Additionally, in vitro vessel formation was established on Si-HA surfaces using a hOB:HDMEC cell ratio of 70:30 and a methodology was established that enabled the assessment of the relative effect of topographical and electrochemical features induced by silicon substitution in the HA lattice on their bioactivity. It was found that the difference in the amount of protein attached to HA and 1.25 wt% Si-HA after 2 h was affected by topographical differences. Conversely, electrochemical differences induced different vessel-like structure formation in coculture with a FN precoating. Without an FN precoating, both topographical and electrochemical differences dictated the differences in angiogenic response. Overall, 1.25 wt% Si-HA surface features appear to induce the most favorable protein adsorption and cell adhesion in mono and coculture with and without FN precoating.

Textural and chemical variations in cassiterite from the Yuanlinzi Sn-Cu deposit, NE China: Insights into ore-forming processes

Microtextural, U–Pb isotopic, and trace element analyses were conducted on magmatic and hydrothermal cassiterites from the Yuanlinzi Sn–Cu deposit (NE China) to determine the timing of mineralization and investigate the ore-forming process. Magmatic cassiterites are disseminated in pegmatite, while hydrothermal cassiterites can be classified into three types: cassiterite-bearing stockworks in pegmatite, disseminated cassiterite in wall rock, and cassiterite-quartz-feldspar veins. U–Pb dating of the four types of cassiterite yields a similar age of ∼ 139 Ma, which is consistent with the ages of regional tin mineralization and granites within the mining district. These results suggest a strong association between Early Cretaceous magmatism and tin mineralization. The four types of cassiterite exhibit comparable textural features, characterized by alternating oscillatory CL zonation and dark homogeneous bands, with the latter commonly enriched in W, Nb, Ta, and U. The direct substitution of tetravalent ions, including Zr, Hf, Ti, and V, with Sn4+ and the coupled substitutions of Fe3+ + OH– = Sn4+ + O2– or Fe3+ + H+ = Sn4+, 2Sb3+ + U6+ = 3Sn4+ and Sc3+ + V5+ = 2Sn4+ are responsible for the incorporation of these elements in cassiterite. The enrichment of W, Nb, Ta, and U in the dark domains of cassiterite is related to the coupled substitution of W + U and Nb + Ta, while the excess of Nb and Ta in the oscillatory-zoned domains may be attributed to the substitution of 4(Nb, Ta)5+ + □ = 5Sn4+. The trace element variations observed in the four types of cassiterite, particularly Al, Sc, Ti, V, and Fe, reflect the ongoing enhancement of the water–rock reaction during the mineralization process. The examination of redox-sensitive elements such as Fe, U, and V suggested that tin mineralization in the Yuanlinzi deposit occurred in an oxidizing environment where oxygen fugacity gradually increased. Additionally, we proposed that the Sc/V ratio of cassiterite could serve as an indicator of the redox state of the associated melt/fluid.

Low dielectric loss and high temperature stability of tri-rutile NiO–SnO2–Ta2O5 ceramics simultaneously achieved by component optimization design

The structural analysis and microwave dielectric characteristics of ionic-modified tri-rutile Ni0·5Sn0·5TaO4 ceramics, focusing on ionic non-stoichiometry and substitution strategies, were systemically studied in this work. A tri-rutile solid solution was unequivocally identified via X-ray diffraction, Raman scatting spectra analysis, and transmission electron microscopy characterization under [110] direction. The unit cell of the tri-rutile structure experiences a contraction primarily due to the compression of the [M2O6] octahedron. An excess of Ni content and the incorporation of (Al1/2Nb1/2)4+ complex cations notably halved the grain size. Conversely, deliberate Sn deficiency led to enlarged grain sizes; however, grain boundaries blurred when the deficiency exceeded 0.03 mol. The microwave dielectric properties are intricately linked to structural characteristics and sintering behavior. Ionic polarizabilities and bulk density predominantly affect the εr value, while grain growth governs variations in the Q × f value. The distortion of [M2O6] octahedra primarily influences the τf value. All measured τf values demonstrated exceptional temperature stability within the range of -5 ∼ +5 ppm/°C. Notably, the Ni0·5Sn0·47TaO4 ceramic displayed outstanding microwave dielectric characteristics: εr = 21.9, Q × f = 45,055 GHz (at f = 10.7 GHz), and τf = -2.07 ppm/°C post-sintering at 1425 °C, rendering it ideal for applications in extreme environmental conditions.

Effect of Rare Earth Ion Substitution on Phase Decomposition of Apatite Structure.

The paper describes an investigation of phase decomposition of apatite lattice doped with rare earth ions (cerium, samarium, and holmium) at temperatures ranging from 25-1200 °C. The rare-earth ion-doped apatite minerals were synthesized using the sol-gel method. In situ high-temperature powder X-ray diffraction (XRD) was used to observe the phase changes and the lattice parameters were analyzed to ascertain the crystallographic transformations. The expansion coefficient of the compounds was determined, and it was found that the c-axis was the most expandable due to relatively weak chemical bonds along the c-crystallographic axis. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to examine the decomposition properties of the materials. Due to rare earth ion doping, the produced materials had slightly variable decomposition behaviour. The cerium and samarium ions were present in multiple oxidation states (Ce3+, Ce4+, Sm3+, Sm2+), whereas only Ho3+ ions were observed. Rare earth ion substitution affects tri-calcium phosphate proportion during decomposition by regulating concentrations of vacancies. X-ray photoelectron spectroscopy (XPS) analysis indicated that cerium and samarium ion-doped apatite yielded only 25 % tricalcium phosphate during decomposition. This finding advances our understanding of apatite structures, with implications for various high-temperature processes like calcination, sintering, hydrothermal processing, and plasma spraying.

Exploring the structural and magnetic properties of La-doped nickel ferrite for microwave absorbing application

The intrinsic properties of microwave absorbing materials are influenced by the permeability and permittivity of the material with indicators of changes in reflection loss characteristics. Nickel ferrite is a magnetic material with very high permeability, so the presence of La3+ ion substitution in nickel ferrite can increase the permittivity of this material and is denoted by increased reflection loss. The magnetic material NiLaxFe(2−x)O4 was synthesized effectively through co-precipitation techniques using NiCl2, FeCl3, and LaCl3 powders, with mole ratios varying from x = 0.01 to 0.04, then continued with the sintering process at a temperature of 1200 °C for 5 h.The X-ray diffraction (XRD) analysis indicates that all NiLaxFe(2−x)O4 samples consist of a single phase of NiFe2O4 with a cubic spinel structure. The scanning electron microscope (SEM) image of NiLaxFe(2−x)O4 powders reveals that all samples exhibit a consistent morphology, however, the powder doesn’t look uniform yet, with particle sizes ranging from 100-800 nm. The magnetic properties of the samples were examined using a vibrating sample magnetometer (VSM). The sample shows ferromagnetic behavior, but the Ms value decreases from 35.89 to 21.54 emu/g and the Hc value increases from 249 to 416 Oe as the La3+ ion content in the material increases. Meanwhile, the microwave absorption capacity measured using the vector network analyzer (VNA) shows that reflection loss increases from 11.16 dB to 15.41 dB as the La3+ ion content in the material increases. So, the substitution of La3+ ions in nickel ferrite structure up toa concentration of x = 0.04 can increase microwave absorption up to 97.11 %.

Sr-doped CuFe2O4 nanoparticles: Exploring structural, magnetic, and blood compatibility characteristics

The aim of this study is to investigate the structural, magnetic, and blood compatibility properties of Sr2+ substituted for Cu2+ in Cu1−xSrxFe2O4 (x = 0.0 to 1 with a 0.25 increment) nanoparticles synthesized via the sol-gel auto-combustion technique. Regardless of the substitution rate, the sol-gel auto-combustion method consistently yields powders with sizes ranging from 20 to 40 nm. The specific surface area of the produced powders is determined as 12 m2/g. X-ray diffraction analysis reveals that CuFe2O4 exhibits a singular phase; however, as the Sr2+ ion substitution increases, the emergence of various secondary phases becomes apparent, with their proportions increasing with the substitution rate. The magnetic characteristics of the synthesized powders exhibit variations in magnetization, correlating with the distribution of cations in the sublattice points. Coercivities are influenced by both anisotropy and secondary phases. Saturation magnetization decreases from 31.3 (CuFe2O4) to 7.6 (SrFe2O4) emu/g with Sr replacement. The lowest observed coercivity is 429.5 Oe in powders prepared with CuFe2O4 composition, while the highest is measured at 583.8 Oe in nanopowders prepared with Cu0.5Sr0.5Fe2O4 composition. Moreover, blood compatibility experiments indicate significantly low hemolysis ratios for Cu1−xSrxFe2O4 nanoparticles. Additionally, all examined samples exhibit an increase in Soret band intensity compared to the negative control test, suggesting potential biocompatibility.

Impact of Cr Doping on the Structural, Optical, and Magnetic Properties of Sol-Gel-Synthesized Bi0.80Ba0.10Pr0.10FeO3 Nanopowders.

The sol-gel route was used to synthesize a series of compounds of the system Bi0.8Ba0.10Pr0.10Fe1-x Cr x O3 within the 0 ≤ x ≤ 0.15 compositional range. To explore the impact of Cr3+ ion substitution on the structural, dielectric, optical, and magnetic properties, we introduced varying concentrations of Cr3+ while maintaining a fixed 10% atomic concentration of each Ba2+ and Pr2+ in BiFeO3. X-ray diffraction analysis revealed a structural phase transition from rhombohedral (R3c) for an undoped (i.e., without Cr) sample to two coexisting phases, i.e., a mix of rhombohedral and orthorhombic (Pbnm) phases for the Cr-doped samples. Cr3+ doping significantly changes the band gap energy from 1.84 eV (x = 0.0) to 1.93 eV (x = 0.15), which makes this material suitable for photovoltaic applications. Furthermore, each sample exhibited ferromagnetic behavior due to the disruption of the spiral spin structures and adjustments in superexchange interactions, attributed to modifications in the Fe-O and Fe-O-Fe bond lengths. A reduction in magnetization is observed at higher Cr concentrations that can be ascribed to the dilution of magnetic moments due to the increase of the orthorhombic phase percentage and the introduction of nonmagnetic Cr3+ ions. Our results show that Cr doping in the Bi0.8Ba0.10Pr0.10FeO3 system induces enhanced multiferroic properties at room temperature.

Incorporation and substitution of ions and H2O in the structure of beryl

Abstract. Incorporation of ions into the crystal structure of beryl (Be3Al2[Si6O18]) can take place by direct ion-to-ion substitution of the framework components Al3+, Be2+ and Si4+ or by occupation of interstitial or structural channel sites. The most common impurities in beryl include transition metals, alkalis and H2O. It is accepted that the transition metals Mn, Cr and V directly substitute for Al at the octahedral site and induce colour. Similarly, the octahedral site can host Fe instead of Al. Nevertheless, it is shown that it remains disputed whether Fe can also be present at the tetrahedral, interstitial, or channel sites, and opposing hypotheses exist regarding these possibilities. However, in the case of Fe, not only the possible occupation of these sites remains under debate, but also their influence on the subsequent colour of beryl. Similarly, the residence of Li in the channels and at the Be tetrahedral or interstitial tetrahedral sites is still under debate. The presence of more than two types of H2O (type I and type II) in the structural channels of beryl is also unclear. This article aims to give an overview on the consensus and on the current debates found in the literature regarding these aspects. It mainly concentrates on the substitution by and the role of Fe ions and on channel occupancy by H2O.

“Study of structural, optical, morphology and magnetic properties of samarium doped magnesium nanoferrites (MgSmxFe2-xO4) using sol-gel auto-combustion method”

The study presents a comprehensive report on Sm3+-doped magnesium ferrite (MgSmxFe2-xO4) and its properties across various x values (0.025, 0.075, 0.1, 0.125, and 0.150). The study utilized multiple characterization techniques, such as X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), UV–visible spectroscopy (UV–vis), Thermogravimetry Differential Thermal Analysis (TG-DTA), High-resolution transmission electron microscopy (HR-TEM), and scanning electron microscopy (SEM) to investigate the structural, magnetic, thermal, optical, and morphological properties of the material. The study determined various parameters, such as x-ray density, lattice constant, crystallite size, and radii on octahedral and tetrahedral sites. An increase in Sm3+ content resulted in an expansion of lattice parameters and a reduction in crystallite size, observed at 13.342 nm in single-phased samples. FT-IR spectroscopy confirmed Sm3+ ion substitution in octahedral sites, while transmission electron microscopy revealed spherical nanoparticles. The UV–vis spectroscopy observed an increase in Sm3+ leads to a corresponding rise in the energy band gap values transitioning from 2.0864, 2.1090, 2.1410, 2.1517, and 2.1850 eV of x = 0.025 to 0.150 respectively. Magnetic measurements indicated decreased magnetization with doping, attributed to particle size dependence. Overall, this study provides valuable insights into the magnetic properties and structural characteristics of Sm3+-doped magnesium ferrite nanomaterials, potentially advancing the development of advanced materials for diverse applications.

Tackling toxicity and stability using eco-friendly metal-halide ion substituted perovskite nanocrystals for advanced display color conversion

In recent years organic–inorganic hybrid halide perovskites nanocrystals have made a remarkable impact in display color converting layer application. However, lead toxicity and stability issues always pose arduous challenges. In this regard, the incorporation of a suitable metal ion to reduce toxicity and enhance stability is a widely tested method. In this study, we used a simple ligand-assisted reprecipitation (LARP) technique to simultaneously introduce metal ion and halide ion substitution by synthesizing MAPb1-xZnxBr3-2xCl2x nanocrystals (NCs). Being eco-friendly with a smaller ionic radius than lead ion, zinc metal ion was chosen as a substitute. With the variation of Zn2+ concentration, the highest quantum yield of 95 % was recorded with an emission width of 21 nm. Temperature-dependent photoluminescence (PL) studies revealed the higher optical phonon-exciton interaction after Zn2+ incorporation leading to radiative transition in NCs. Variation of PL peak energy with temperature revealed the reduced thermal chromaticity of Zn2+ incorporated NCs making them suitable for display application. Further, these NCs maintained a stable cubic structure and luminescence up to 150 °C, indicating higher thermal stability. The MAPb0.9Zn0.1Br2.8Cl0.2 (x = 0.1 or 10 mol%) NCs embedded in PMMA (poly (methyl methacrylate) polymer matrix coated LED emits narrow width, green light with color coordinate (0.15, 0.79), which is closer to green coordinate (0.17, 0.79) in Rec.2020. This helps to reproduce close to 97 % color gamut of Rec.2020. This research paves the way for finding less toxic and stable green light-emitting materials instead of cadmium-based molecules.

Structural, Optical, and Morphological Study of Manganese Substituted Cobalt Ferrite and Its Effect on the Magnetic and Dielectric Properties of PVA Composites

Nanopowders of Mn-substituted CoFe2O4 were prepared in different proportions using the sol-gel auto-combustion method and were structurally and morphologically studied. In another step, composites based on polyvinyl alcohol (PVA) with Mn-substituted CoFe2O4 fillers were prepared, and the effect of the Mn-substituted CoFe2O4 on the optical, magnetic, and dielectric properties was studied. X-ray analysis revealed the formation of polycrystalline Mn-substituted CoFe2O4. The results showed a decrease in the lattice constant with Mn2+ substituted and incorporated into the crystal structure of CoFe2O4. The Fourier confirmed the spinel structure of the Mn-substituted CoFe2O4 transform infrared spectrum where absorption bands appeared at 569–561 and 446–407 cm-1, which are attributed to tetrahedral and octahedral groups. The magnetic properties were affected when Mn ions were substituted with CoFe2O4, as shown by the results of VSM. It was observed that the saturation magnetization, remnant magnetization, and coercivity decreased with increasing Mn content. The dielectric constant and loss tangent of PVA/MnxCo1−xFe2O4 were also studied. The difference in the diameters of the substituted and host ions causes the dielectric constant to increase following the substitution of Mn ions.