Bi Substitution Research Articles

Influence of Bi substitution on structural and optical properties of LaFeO\(_{3}\) perovskite

The sol-gel self-ignition method has successfully synthesized a series of homogenous perovskites La1-xBixFeO3 (x=0.0, 0.2, 0.4, 0.6, and 0.8) nanoparticles. Rietveld refinement results from XRD patterns revealed no secondary phases in pure and Bi-substituted LaFeO3 samples. The structural transition from orthorhombic at x = 0.0 until x=0.6 (space group Pbnm) to rhombohedral at x=0.8 (space group R3c) was observed. Lattice parameter values increase slightly with Bi concentration due to the substitution of Bi in the LaFeO3 structure. The average crystallite size D was found to vary between 19 nm and 50 nm. The combination of XRD and SEM demonstrated that the prepared Bi-doped LaFeO3 is a single-phase perovskite with a relatively homogeneous particle size distribution. SEM images revealed quasi-spherical particle shapes. FTIR spectra identify the metal oxide bending vibrations at about 536 cm‒1 and 717 cm‒1 attributed to Fe-O and La-O bonds, respectively. No significant effect of Bi substitution from 0% up to 60% on crystal volume was observed, as confirmed by FTIR spectroscopy, which showed no shift in La/Fe-O bending vibration modes with increasing Bi content. The obtained results indicated that the Eg values exhibited a monotone decrease with an increase in Bi ratio. The band gap values varied from 2.2 eV for pure LaFeO3 to 1.85, 1.76, 1.54 and 1.35 eV for the substitutions of 20%, 40%, 60% and 80% respectively. Hence, the sample La0.2Bi0.8FeO3 with the small band gap value can be used as a promising candidate in solar cell applications.

Correlation Between the Crystal Structure and Magnetic Properties of Bi1−yCayFe1−xMnxO3 Multiferroics near the Polar-Anti(non)polar Phase Boundary

This paper reports the results of a systematic investigation into the magnetic properties of Bi1−yCayFe1−xMnxO3 (0.1 ≤ y ≤ 0.175, 0.35 ≤ x ≤ 0.45) solid solutions. The substitution of Bi3+ with Ca2+ and the concurrent introduction of Mn3+/Mn4+ ions result in the stabilization of various structural phases, with each exhibiting distinct magnetic characteristics. The investigation indicates that the samples containing the polar rhombohedral phase display metamagnetic transitions at low temperatures, characterized by pronounced jumps in magnetization. Single-phase samples with a nonpolar orthorhombic structure exhibit weak ferromagnetic behavior without metamagnetic features. The observed metamagnetic behavior, accompanied by anomalies in temperature-dependent magnetization and significant remnant magnetization at low temperatures, particularly in samples near the polar-anti(non)polar phase boundary, highlighted the presence of both antiferromagnetic and glassy magnetic components.

Anomalous lattice contraction and emerging topological phases in Bi-substituted Sm2Ir2O7

We demonstrate that substituting Bi for Sm in the pyrochlore Sm$_2$Ir$_2$O$_7$ induces an anomalous lattice contraction, with $\Delta a \sim -0.012$~\AA~observed at 10\% Bi substitution, where 'a' denotes the lattice constant. Beyond 10\% Bi substitution, the lattice expands according to Vegard's law. Within this anomalous substitution range, the resistivity shows a 1/T behavior up to 2\% Bi-substitution, while near 10\% substitution a -lnT dependence is observed. These resistivity behaviors suggest the possibility of a Weyl phase up to 2\% Bi substitution, which transforms to a semimetallic quadratic band touching (QBT) topological phase near 10\%. For the intermediate composition (Sm$_{0.95}$Bi$_{0.05}$)$_2$Ir$_2$O$_7$, the resistivity scales as $\rm 1/T^{1/4}$, possibly due to its proximity to a proposed quantum critical point at the Weyl-QBT phase boundary [Phys. Rev. X 4, 041027 (2014)]. The samples were characterized using synchrotron powder X-ray diffraction, X-ray near-edge fine structure (XANES), and Extended X-ray absorption fine structure (EXAFS) probes. Additionally, magnetic susceptibility and heat capacity measurements were conducted to provide further support.

Evidence and engineering of x-ray luminescence in lead free perovskite Cs2AgInCl6 with Bi substitutions

Cs2AgInCl6 belongs to the family of lead-free halide double perovskites. Lead-free halide double perovskite appears as a viable contender for scintillator applications due to its inexpensive production costs, low intrinsic trap density, and nanosecond quick reaction. Perovskite crystals have a substantially lower trap density than lead halide and traditional oxide scintillator materials, according to thermo-luminescence measurements. Cs2AgInCl6 structure and dimensionality were engineered by Bi doping. Bi substitution reduces the bandgap, making it suited for scintillation applications. Bi substitution allows for easy tuning of Cs2AgIn(1−x)BixCl6 (0 ≤ x ≤ 50) due to its wide versatility in scintillation properties. For Cs2AgIn(1−x)BixCl6 (0 ≤ x ≤ 50), x-ray power dependent luminescence increases with increasing power. Because of their nontoxicity, sensitivity, reaction time, and stability, Cs2AgIn(1−x)BixCl6 (0 ≤ x ≤ 50) double perovskite crystals are promising for x-ray scintillation.

Morphologically and Compositionally Controlled Cs2SbBr6 by Bi and Ag Substitution

AbstractMorphology‐controlled Cs2SbBr6 crystals are synthesized by Bi‐ and Ag‐substitution of the precursor solution. X‐ray diffraction (XRD) together with Raman spectroscopy confirms the lattice tilting and symmetry changes with the dominant appearance of higher index facets by Bi substitution. Ag substitution does not induce crystal symmetry changes in the Cs2BBr6 (B = Sb or Bi) phase, but results in highly defective structures hindering the formation of a smooth surface during the crystal growth. Successful substitution of Bi and limited substitution of Ag into Cs2SbBr6 is also confirmed by energy dispersive X‐ray spectroscopy (EDX). This research provides design principles and practical examples of how to control the morphology of Cs2SbBr6 crystals with structural defects and multiphase formation.

Potential improvement in thermoelectric properties of SnTe polycrystals via anionic and cationic substitution

Heat is produced by all machinery, including microprocessors and jet engines, as well as by industrial processes that produce goods from steel to food. There is still a strong desire for alternative energy sources in this day of ecologically conscious and sustainable energy needs. The recovery of heat from waste heat into beneficial electrical energy provides a simple energy source with enormous potential. Thermoelectrics is one of the popular technologies, which can convert heat into electricity, making them useful for power generation. Tin telluride (SnTe), a significant type of newly developed thermoelectric material, has drawn a lot of attention due to its low toxicity and environmentally friendly characteristics. Here, we synthesize Bi/Se co-doped SnTe (Sn1-xBixTe0.97Se0.03 (x = 0, 0.02, 0.04, 0.06)) samples by employing the solid-state metathesis route. The results of this work suggest that the combined action of cationic and anionic substitution of Bi and Se to SnTe matrix could potentially modify the microstructure and band structure of SnTe, thereby effectively improving its electronic, mechanical, and thermal transport properties. In line with the experimental findings, the samples show degenerate semiconducting electronic transport behaviour throughout the temperature range. The maximum Seebeck coefficient is found to be ∼84 μV/K and the total thermal conductivity is reduced to 1.6 W/mK at 573 K in a 6 % Bi-doped sample, which is 2.2 times less than the pristine sample. The Sn0.94Bi0.06Te0.97Se0.03 sample has a maximum ZT of approximately 0.23 at 573 K, which is three times higher than the pristine sample because of the combined regulation of cation-anion co-doping and an elevated power factor of 936 μW/K2m in Sn0.96Bi0.04Te0.97Se0.03 sample at 573 K, which is 1.82 times higher than that of pristine SnTe. Considering these findings, it appears that Bi-Se co-doped SnTe is a promising material for thermoelectric applications.

Tailoring the structural and optical properties of lead-free Na0.5(Bi1-xSmx)0.5TiO3 multifunctional ceramics by Sm-doping

In this study, the effects of Sm3+-content on the structural and optical properties of the Na0.5(Bi1-xSmx)0.5TiO3 multifunctional lead-free system were investigated using x-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Raman spectroscopy and photoluminescence (PL) spectroscopy. The Na0.5(Bi1-xSmx)0.5TiO3 (x = 0.000, 0.005, 0.010, 0.015, and 0.020) ceramics were synthesized by the solid-state reaction method with subsequent annealing. The Rietveld method was used to refine the XRD data. The results of these refinements indicated that pure NBT (Na0.5Bi0.5TiO3) and the Sm3+-doped samples showed the coexistence of the rhombohedral (R3c) and tetragonal (P4bm) phases in different fractions, which depend on the Sm3+-content. The UV-Vis data revealed that the optical band gap of the Na0.5(Bi1-xSmx)0.5TiO3 samples monotonically decreases with increasing Sm3+-content, providing evidence of replacement of Bi3+- by Sm3+-ions. Furthermore, Raman spectroscopy confirmed that substitution of Bi3+- by Sm3+-ions leads to a shortening of the Na/Bi-O bond length. It was demonstrated that this behavior is responsible for the increase in the local symmetry of the TiO6 octahedron and the consequent decrease in the ratio between both rhombohedral and tetragonal phases, as observed by the XRD data. The findings from the PL data revealed typical emissions corresponding to transitions between the 4G5/2 → 6Hj (j = 5/2, 7/2, 9/2, 11/2, 13/2) states of the Sm3+-ion. Additionally, the presence of non-radiative recombination processes was found to depend on both laser pumping power and Sm3+-content.

Study of spin-phonon interaction in multiferroic La0.9Bi0.1CrO3 by Raman spectroscopy

Spin-phonon interaction is an interesting phenomenon that may find applications in spintronics, quantum information processing, etc. In multiferroic materials, spin-phonon interaction, if exists, may provide additional degrees of freedom that could lead to the development of novel technologies. Thus, investigating and understanding this interaction in a multiferroic material is of both fundamental and applied interests. Perovskite La1-xBixCrO3 is a mutiferroic material which turns from antiferromagnetic/antiferroelectric to ferromagnetic/ferroelectric with 10 % substitution of Bi3+ for La3+. Raman spectrum feature changes dramatically with 10 % substitution of Bi3+ for La3+ also, indicating a spin-phonon interaction. Furthermore, in La0.9Bi0.1CrO3, the ∼700 cm−1 mode is split into two Raman sub-modes. The intensity of the lower frequency (680 cm−1) sub-mode starts increasing sharply around the Néel temperature TN = 269 K upon cooling. Below TN, the monotonic change in intensity reflects the magnetic exchange modulation, resulted from the interacting with the chromium atoms oscillation at the original Cr4+ position in LaCrO3, related to the competing ferromagnetic and antiferromagnetic interactions, with the former prevailing at low temperatures. The interplay of magnetic exchange modulation interactions and chromium atoms oscillation (decreasing of the lower frequency sub-mode of the Bi3+ doping related John-Teller-like 700 cm−1 mode) coincides with the corresponding magnetic phase transition (TN), demonstrating a spin-phonon coupling in La0.9Bi0.1CrO3 which may find applications in magnonic devices.

Type-II superconductivity at 9K in Pb–Bi alloy

In the present work, we report the synthesis of Pb–Bi alloy with enhanced Tc of up to 9K, which is higher than that of Pb. The alloy is synthesized via a solid-state reaction route in the vacuum-encapsulated quartz tube at 700°C in an automated furnace. The synthesized sample is characterized by X-ray Diffraction(XRD) and Energy dispersive X-ray analysis(EDAX) for its phase purity and elemental composition. Rietveld refinement of XRD reveals that the end product is a majority hexagonal Pb7Bi3, with minor rhombohedral Bi. The electronic transport measurement shows metallic behavior with the Debye temperature of 108K and a superconductivity transition temperature (Tc) below 9K, which is the maximum to date for any reported Pb–Bi alloy, Pb or Bi at ambient pressure. Partial substitution of Bi at the Pb site may modify the free density of electronic states within the BCS model to attain the optimum Tc, which is higher by around 2K from the reported Tc of Pb. The superconductor phase diagram derived from magneto-transport measurements reveals that the synthesized alloy is a conventional superconductor with an upper critical field (Hc2) of 3.9 T, which lies well within the Pauli paramagnetic limit. The magnetization measurements carried out following ZFC(Zero Field Cool) protocols infer that the synthesized alloy is a bulk superconductor below 9K. The isothermal M-H(Magnetization vs. Field) measurements performed below Tc establish it as a type-II superconductor. The specific heat capacity measurements show that the Pb–Bi alloy is a strongly coupled bulk superconductor below around 9K with possibly two superconducting gaps.

Insights into crystal structure, temperature-dependent magnetization and dielectric relaxation mechanism in Bi substituted samarium iron garnet

The single phase Sm3−xBixFe5O12 with x=0.0,0.2,0.4 and 0.6 samples are synthesized by solid-state reaction method. We have systematically studied the structural, morphological, temperature dependent magnetic and electric properties. All the samples crystallize in simple cubic crystal structure and belongs to Ia3‾d space group. The lattice constant and bond angle between Fe(a)−O−Fe(d) network is enhanced with Bi substitution. As a result, the ferrimagnetic transition temperature is also enhanced from 565K to 569K. We have examined the applicability of Bloch's and Cojocaru's laws to our temperature-dependent magnetization data and find that Bloch's T3/2 law is not suitable due to geometrical asymmetry, long wavelength excitation, and local atomic disorders. However, Cojocaru's law which accounts for the geometrical aspects, provides a better fit to our magnetization data. Further, the impedance plots at room temperature exhibit no relaxation which is attributed to the limited mobility of charge carriers. On the other hand, the high temperature impedance data represents dielectric relaxation at a particular frequency. This frequency is used to determine the relaxation time which is fitted to Arrhenius law and activation energy is evaluated. The activation energy lies in between 0.24−0.32eV which corresponds to the singly ionized oxygen vacancies. The conduction mechanism is analyzed with Variable range hopping model and the average hopping length and hopping energies are also determined for these garnet samples.

Impedance spectroscopy and electrical conductivity of 0.7Bi(1−x)NdxFeO3–0.3BaTiO3 ferroelectric ceramics

0.7Bi[Formula: see text]NdxFeO3–0.3BaTiO3 (BNFO–BTO, [Formula: see text], 0.010, 0.020 and 0.050) ceramics were fabricated using the high-temperature solid-state reaction method. The X-ray diffraction (XRD) patterns revealed that the primary phase in these ceramics was pseudocubic. The Scanning Electron Microscopy (SEM) micrographs exhibited dense microstructures throughout all BNFO–BTO ceramics. Furthermore, the temperature dependence of dielectric behaviors and ferroelectric hysteresis loop shapes suggested the occurrence of a relaxor ferroelectric-type phase transition in BNFO–BTO ceramics. Additionally, the frequency dispersion characteristics and remnant polarization were enhanced with increasing substitution of Bi[Formula: see text] by Nd[Formula: see text]. Conducted impedance analysis on 0.7Bi[Formula: see text]NdxFeO3–0.3BaTiO3 ceramics and two dielectric responses of the grain at high frequency and grain boundary at low frequency were illustrated, respectively. The combination of imaginary impedance ([Formula: see text] and imaginary modulus ([Formula: see text] versus log[Formula: see text]f plots revealed that the charge carriers’ motion was not entirely long-range, short-range migration also exists. Through calculations based on Curie–Weiss Law, the relaxation activation energy ([Formula: see text] and conductance activation energy ([Formula: see text] were investigated, confirming that doping Nd[Formula: see text] effectively mitigates the concentration of oxygen vacancies (OVs) and prevents the formation of oxygen vacancies clusters, ultimately suppressing conductivity in BNFO–BTO ceramics.

Realizing high average zT in GeTe through band modulation and suppressing Ge vacancies

GeTe is regarded as an excellent thermoelectric material, while its intrinsically high hole concentration impedes its further enhancement in thermoelectric performance. In this work, we introduce a two-step strategy by Bi and Y co-doping and Pb alloying to optimize the thermoelectric properties of the GeTe compound. Aliovalent Bi doping on the Ge site is found to effectively reduce the hole concentration, and a small substitution of Bi by Y atoms can further increase the effective mass, resulting in a high thermoelectric figure of merit (zT) of ∼ 1.92 at 723 K. Alloying Pb with high concentration elaborately decreases the carrier concentration to around 1.09 × 1020 cm−3, leading to an enhancement of Seebeck coefficient. In addition, Pb alloying maintains stable carrier mobility, contributing to a high power factor. PbTe alloying induces a strong point defect scattering and strain field fluctuation, leading to a low lattice thermal conductivity. Benefiting from the synergistically optimized effects of Bi and Y co-doping and Pb alloying, a peak zT of ∼ 2.26 at 723 K and an average zT of 1.64 over 300–773 K are realized in Ge0.8Pb0.15Bi0.04Y0.01Te.

Enhancement of magnetocaloric effect by partial substitution of Bi in La0.60Dy0.10Sr0.30Mn(1−x)BixO3 manganites (x = 0, 0.01, 0.03, and 0.10)

In this study, the effects of Bi substitution for Mn on the magnetic and magnetocaloric properties of La0.60Dy0.10Sr0.30Mn(1−x)BixO3 manganites (x = 0, 0.01, 0.03, and 0.10) synthesized using the sol–gel method ​​were investigated. The samples x = 0, 0.01, and 0.03 had been indexed in an orthorhombic structure (space group Pnma), while sample x = 0.10 had been indexed in a hexagonal structure (space group R3c). The thermomagnetic measurements showed an increase in the Curie temperature (TC) with increasing Bi content, as well as an increase in magnetization at low temperatures. The TC values were determined as 322, 318, 327, and 360 K for x = 0, 0.01, 0.03, and 0.10 samples, respectively. Maximum magnetic entropy change (-ΔSMmax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-\\Delta {S}_{M}^{max}$$\\end{document}) values ​​obtained from isothermal magnetization measurements showed an increase with the amount of Bi. The -ΔSMmax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-\\Delta {S}_{M}^{max}$$\\end{document} value of 3.80 Jkg−1K−1 at 5 T for the x = 0 sample increased to 4.12 Jkg−1K−1 for the x = 0.10 sample with the highest Bi content. From the Arrott curves, it was observed that all samples exhibited a second-order magnetic phase transition. The obtained values of relative cooling power (RCP), which is an important factor in determining the performance of cooling material, are in the range of 282, 262, 251, and 232 Jkg−1 for x = 0, 0.01, 0.03, and 0.10, respectively.

Band Gap Narrowing by Suppressed Lone-Pair Activity of Bi3.

Post-transition metal cations with a lone pair (ns2np0) electronic configuration such as Pb2+ and Bi3+ are important components of materials for solar-to-energy conversion. As in molecules like NH3, the lone pair is often stereochemically active in crystals, associated with distorted coordination environments of these cations. In the present study, we demonstrate that suppressed lone pair stereochemical activity can be used as a tool to enhance visible light absorption. Based on an orbital interaction model, we predict that a centrosymmetric environment of the cations limits the orbital interactions with anions, deactivates the lone pair, and narrows the band gap. A high-symmetry Bi3+ site is realized by isovalent substitutions with Y3+ by considering its similar ionic radius and absence of a lone pair. The quaternary photocatalyst Bi2YO4X is singled out as a candidate for Bi substitution from a survey of the coordination environments in Y-O compounds. The introduction of Bi3+ to the undistorted Y3+ site in Bi2YO4X results in a narrowed band gap, as predicted theoretically and confirmed experimentally. The orbital interaction controlled by site symmetry engineering offers a pathway for the further development of post-transition metal compounds for optoelectronic applications.

Site preference and local structural stability of Bi(III) substitution in hydroxyapatite using first-principles simulations.

Bismuth (Bi(III)) substitution in hydroxyapatite (HAp) lattice confers unique properties such as antibacterial, catalytic, radiosensitization, and conductive properties while preserving the innate bioactivity. Understanding the local structural changes upon Bi3+ substitution is essential for controlling the stability and optimizing the properties of HAp. Despite numerous experimental studies, the precise substitution behaviors, such as site preference and structural stability, remain incompletely understood. In this study, the substitution behavior of Bi(III) into the HAp lattice with formula of Ca9Bi(PO4)6(O)(OH) was investigated via first-principles simulation by implementing density functional theory. Energy calculations showed that Bi3+ preferentially occupies the Ca(2) site with an energy difference of ∼0.02 eV per atom. Local structure analysis revealed higher bond population values and an oxygen coordination shift from 7 to 6 for the Ca(2) site, attributed to the greater covalent interactions and its flexible environment accommodating the bulky Bi3+ ion and its stereochemically active lone pair. This work provides the first comprehensive investigation on Bi3+ ion substitution site preference in HAp using first-principles simulations.

Weak electron-phonon coupling contributing to enhanced thermoelectric performance in n-type TiCoSb half-Heusler alloys

n-type TiCoSb half-Heusler (HH) alloys show lower thermoelectric performance may be notably owing to the low valley degeneracy of the conduction band. Here, we show that this drawback can be counterbalanced by a decrease in the deformation potential coefficient and hence, weak electron-phonon coupling strength driven by the substitution of Nb for Ti in the n-type alloys Ti1-xNbxCoSb0.96Bi0.04. The combined substitutions of Nb and Bi yield a reduction of ∼86% in the deformation potential of the conduction band minimum, with the lowest value of ∼5 eV at 300 K achieved in Ti0.85Nb0.15CoSb0.96Bi0.04. This effect leads to enhanced power factor from ∼0.018 mW m−1 K−2 for x = 0 to ∼1.69 mW m−1 K−2 for x = 0.15 at RT due to the resulting strong increase in electron mobility by one order of magnitude. Both the isovalent Bi and aliovalent Nb substitutions further contribute to decrease the lattice thermal conductivity owing to enhanced mass and strain field fluctuations. The beneficial combined effects of weaker electron-phonon coupling and enhanced point-defect phonon scattering results in a higher dimensionless thermoelectric figure of merit ZT, with a peak value ∼ 0.37 at 870 K in Ti0.85Nb0.15CoSb0.96Bi0.04, representing a ∼ 375% improvement with respect to pristine TiCoSb.

Tuning martensitic transformation and magnetocaloric effect with Bi substitution in MnCo1-xBixGe alloys

In this work, the substitution of Bi for Co atoms in MnCo1-xBixGe (x = 0.01, 0.02, 0.04, 0.06, 0.08, 0.1) alloys was prepared. The crystal structure, magnetic properties, and magnetocaloric effect have been analyzed. By tuning the Bi-content in MnCoGe alloys, the reduction of martensitic transformation (MT) temperature and the presence of a first-order magnetostructural transition (MST) were observed. Magnetic field-induced MT indicates that the magnetic field is much harder to drive MT compared to the temperature. With the Bi-content for 0.01 ≤ x ≤ 0.06, orthorhombic-type phase and hexagonal-type phase coexist. Furthermore, we observed an increase in the fraction of the hexagonal-type phase and a corresponding decrease in the fraction of the orthorhombic-type phase. It is beneficial to the refrigeration capacity for the isothermal magnetization curves M(H) on magnetization and demagnetization procedures with small magnetic hysteresis loss. With a magnetic field of 5 T, magnetocaloric effect (MCE) can be observed involving magnetic entropy change (-ΔSM) of 26.42 J kg−1 K−1 for x = 0.06 and refrigeration capacity (RC) of 259.78 J kg−1 for x = 0.01. Thus, this material is considered a fabulous candidate for magnetic refrigeration cooling applications at room temperature.

Characterization of Bi substitution of strontium cobalt zinc ferrites synthesized by micro-emulsion technique

Strontium cobalt zinc bismuth ferrites with formula are provided in this study using formula Sr0.5Co0.4Zn0.4BixFe2-xO4 at different variation of x= 0.0, 0.05, 0.10, 0.15 synthesized by Micro-emulsion techniques. To check the physical characteristics of this series (Sr0.5Co0.4Zn0.4BixFe2-xO4) of nano-ferrites using FTIR (Fourier Transformation of infrared spectroscopy), UV-visible, X-ray diffraction and scanning electron microscope. SEM and XRD analysis were used to examine the structure and morphology of manufactured nano-ferrites. The spectra of XRD demonstrated the production of a single-phase cubic spinel ferrite structure in the nanometer size range with no minor phase. When extending metal-oxygen bonds at tetrahedral and octahedral sites, FTIR analysis showed two bands centered at 592 and 410 cm-1 . Using ultraviolet-DRS, we determined that band-gap range for the synthesised magnetic materials was between 2.42 and 2.32 eV.

The synergistic effects of dual substitution of Bi and Ce on ionic conductivity of Li7La3Zr2O12 solid electrolyte

Li7La3Zr2O12 (LLZO) is a promising solid-state electrolytes (SSE) candidate with high ionic conductivity, wide electrochemical window, good chemical stability and thermal stability. However, LLZO is unstable at room temperature and is easily converted from a cubic structure to a tetragonal structure, resulting in a decrease in ionic conductivity. Stable cubic phase LLZO can be obtained by element doping and the ionic conductivity can be improved. We found that the doping of Bi and Ce can reduce the sintering temperature and increase the ionic conductivity, among which the Li7La2.5Ce0.5Zr1.625Bi0.3O12 (LLCZBO) solid electrolyte has the highest ionic conductivity of 5.12 × 10−4 S cm−1 and the electronic conductivity of 2.72 × 10−10 at room temperature. LLCZBO prepared by sol-gel method can reduce the sintering temperature and improve the degree of densification. These results indicate that double-doped Bi and Ce is a simple and effective strategy to develop oxide solid electrolytes with high ionic conductivity.

High-performance lithium metal batteries based on composite solid-state electrolytes with high ceramic content

The large scale application of solid state lithium metal batteries based on NASICON-type Li1+xAlxTi2-x(PO4)3 (LATP) electrolyte has been hindered by insufficient ion conductivity and interface instability due to the spontaneous Ti4+ reduction reaction between Li metal and LATP. To address these issues, Li1.7Al0.3-xBixTi1.7(PO4)3 (0 ≤ x ≤ 0.03) (LABTP) electrolytes were prepared, and the influence of Bi substitution on the microstructure and conductivity of LATP were investigated. Suitable amount of Bi substitution accelerates densification and improves the ionic conductivity. Furthermore, unlike commonly used polyethylene oxide (PEO) and polyvinylidene difluoride (PVDF), polyvinylbutyral (PVB)-based quasi-solid electrolytes with LABTP is first-time proposed to improve the compatibility and stability of the LATP/Li interface. The synergistic effect of Bi doping and PVB reduces the reduction reaction of Ti4+. Small voltage hysteresis is observed in the corresponding Li||Li symmetric cells. The solid-state Li|LABTP@PVB|LiFePO4 full cell can deliver a high capacity of 146.2 mAh g−1 and a stable cycling performance without reduction after 200 cycles.