Using anodic aluminum oxide templates and electrochemical method to deposit BiSbTe-based thermoelectric nanowires

In this study, the cyclic voltammetry method was first used to find the reduced voltages and anodic peaks of Bi³⁺, Sb³⁺, and Te⁴⁺ ions as the judgments for the growth of the (Bi,Sb)_{2 - x} Te_{3 + x}-based materials. Ethylene glycol (C₂H₆O₂) was used as a solvent, and 0.3 M potassium iodide (KI) was used to improve the conductivity of the solution. Two different electrolyte formulas were first used: (a) 0.01 M Bi(NO₃)₃-5H₂O, 0.01 M SbCl₃, and 0.01 M TeCl₄ and (b) 0.015 M Bi(NO₃)₃-5H₂O, 0.005 M SbCl₃, and 0.0075 M TeCl₄. The potentiostatic deposition process was first used to find the effect of reduced voltage on the variation of compositions of the (Bi,Sb)_{2 - x}Te_{3 + x}-based materials. After finding the better reduced voltage, 0.01 M Bi(NO₃)₃-5H₂O, 0.01 M SbCl₃, and 0.01 M TeCl₄ were used as the electrolyte formula. The pulse deposition process was successfully used to control the composition of the (Bi,Sb)_{2 - x}Te_{3 + x}-based materials and grow the nanowires in anodic aluminum oxide (AAO) templates.     

Effect of M3+ (M = Bi,Al) co-doping on the luminescence enhancement of Ca2ZnSi2O7:Sm3+ orange-red−emitting phosphors

In this paper, the luminescence properties of Ca₂ZnSi₂O₇:Sm³⁺ phosphors were improved by co-doping with M³⁺ (M = Bi, Al) via the sol-combustion method. The structure and luminescence properties of the Ca₂ZnSi₂O₇:Sm³⁺, M³⁺ samples were investigated in detail, especially the luminescence enhancement effect of Bi³⁺/Al³⁺ co-doping. XRD results indicated that moderate Bi³⁺/Al³⁺ co-doping in the host structure did not change the tetragonal structure of Ca₂ZnSi₂O₇. The series of Ca₂ZnSi₂O₇:Sm³⁺, M³⁺ phosphors could be excited by 402 nm near-ultraviolet light and several significant emission peaks were obtained at 567, 604 and 650 nm, which originated from the electron transitions of Sm³⁺ from ⁴G_5/2 to ⁶H_5/2, ⁶H_7/2 and ⁶H_9/2 levels, respectively. The luminescence intensity of Ca₂ZnSi₂O₇:Sm³⁺ was markedly enhanced through Bi³⁺/Al³⁺ co-doping, which could be explained by Al³⁺ decreasing the crystal field symmetry and greatly increasing the red luminescence intensity, and Bi³⁺ functioning as a sensitizer to increasing the luminescence intensity through energy transfer from Bi³⁺ to Sm³⁺ ions. In conclusion, the excellent Ca₂ZnSi₂O₇:Sm³⁺, M³⁺ phosphors have potential application as red phosphors in white light emitting diodes.     

Effect of Bismuth substitution on the enhancement of thermoelectric power factor of nanostructured BixCo3-xO4

Bismuth Cobalt Oxide (Bi_xCo_3-xO₄) nanoparticles with different compositions (x?=?0, 0.025, 0.05, 0.1, 0.2) were prepared by chemical precipitation method. The structural, morphological and thermal properties of the prepared samples were studied by XRD, SEM, FTIR and TG&DTA analysis. X-ray diffraction analysis shows that pure phase of Cobalt oxide was formed till x?≤?0.05 and while increasing the Bi concentration (0.05?≤ x?≤?0.2) mixed phases of Co₃O₄, Co₂O₃, CoO and separate phase of Bi₂O₃ were formed. The diffraction peaks were reasonably shifted due to substitution of Bi²⁺ ions. XPS analysis conforms the presence of mixed valance states of Co and presence of Bi with their binding states in the samples. The electrical resistivity and Seebeck coefficient were measured for Bi_xCo_3-xO₄ (0?≤ x?≤?0.2) at different temperatures. It was observed that the electrical resistivity decrease till x?≤?0.05 due to the substitution of Bi ions in Cobalt lattice and increases at higher x values (0.05?≤ x?≤?0.2) due to the formation of Bi₂O₃ phase. The Bi substitution has considerably reduced the electrical resistivity by one order when completely dissolved in the cobalt oxide lattice at lower x values. The Seebeck coefficient value gradually increased for all samples of Bi_xCo_3-xO₄ (0?≤ x?≤?0.2). The power factor was calculated from electrical resistivity and Seebeck coefficient and the maximum power factor of 0.025 µWm^?1K^?2 was obtained for Bi_0.2Co_2.8O₄ sample at 530?K. The experimental results revealed that the Bi substitution have promising effect on the thermoelectric properties of nanostructured Bi_xCo_3-xO₄ (0?≤ x?≤?0.2).     

Electrochemical performances of Bi based compound film-coated ZnO as anodic materials of Ni–Zn secondary batteries

Microstructures and electrochemical performances of Bi based compound film-coated ZnO are investigated and compared with those of Ni film-coated ZnO and Bi nanocompound-modified ZnO in order to illuminate the coating effect of Bi based compound film. Bi based compound film is composed of nanoparticles (1–2 nm in diameter) of Bi₆(NO₃)₄(OH)₂O₆, BiO and Bi₂O₃, containing lots of micropores. In comparison with Bi nanocompound-modified ZnO and Ni film-coated ZnO, Bi based compound film-coated ZnO shows higher discharge capacity and more stable cycling performance. The highest average discharge capacity is as high as 535 mAh g⁻¹, and the discharge capacity does not obviously decrease during the cycling tests. Cyclic voltammograms indicates that Bi based compound film can limit transfer of H₂O, OH⁻, and enhance electrochemical activity of ZnO. The improvement of cycling performance is due to: (1) the coating film structure avoids the direct contact between ZnO/Zn with the electrolyte, and suppresses the dissolution of ZnO/Zn; (2) the micropores in the film is beneficial to adequate diffusion of H₂O, OH⁻ and zincates ions, leading to high discharge capacity and good cycling performance; (3) the light weight of the film also has a contribution to high specific discharge capacity.     

Electrodeposition of bismuth telluride films from a nonaqueous solvent

The author examines Bi₂Te₃ deposition from a DMSO solution containing TeCl₄ and Bi(NO₃)₃ × 5H₂O by means of cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM). Accumulated charges and related mass changes for Bi₂Te₃ deposition on working electrodes are measured in situ. The deposit composition is more dependent on Te⁴⁺ concentrations in DMSO solution than on the potential. In a DMSO solution containing 0.01 M Te⁴⁺ and 0.0075 M Bi³⁺, Bi₂Te₃ deposits were obtained in the potential range between −0.2 and −0.8 V vs. Ag/AgCl. In a DMSO solution containing 0.05 M Te⁴⁺ and 0.0375 M Bi³⁺, Te-rich deposits were formed from −0.2 to −0.8 V vs. Ag/AgCl.     

Bi2O3 induced tremella-like Bi2WO6 with visible light catalytic performance

The development of single phase photocatalyst is expected to realize clean energy and pollution treatment. Herein, we reported a novel Tremella-like Bi₂WO₆ catalyst which was obtained by facile hydrothermal technique. The formation of Tremella-like Bi₂WO₆ strongly depended on introduction of Bi₂O₃. Based on the Kirkendall effect, Bi₂O₃ induced Bi(NO₃)₃·5H₂O to form biscuit-like Bi₆O₆(OH)₃(NO₃)₃·3H₂O particles which provided templates and reacted simultaneously with WO₄^2? to synthesize Tremella-like Bi₂WO₆. The Tremella-like Bi₂WO₆ exhibited remarkable visible-light catalytic performance. The degradation rate of RhB dye reached 100% with 10 min, the reduction rate of CO₂ was 5.5 times higher than pure Bi₂WO₆. Moreover, the Tremella-like Bi₂WO₆ catalyst displayed excellent stability during the recycle experiments. The high catalytic activity makes single phase Bi₂WO₆ catalyst great potential in environmental protection field.     

Synthesis,optical, and magnetic properties of six-layered Aurivillius bismuth ferrititanate

This work reports on the preparation, structure, photochemical, and magnetic properties of six-layered Aurivillius bismuth ferrititanates, that is, Bi₇Ti₃Fe₃O₂₁, Bi₇(Ti₂Nb)Fe₃O_21+δ, and Bi₇(Ti₂Mg)Fe₃O_21−δ nanoparticles. The samples were prepared through the modified citrate complexation and precursor film process. The XRD Rietveld refinements were conducted to study the phase formations and crystal structure. The morphological and chemical component characteristics were investigated using SEM, TEM, and EDX analyses. Bi₇Ti₃Fe₃O₂₁, Bi₇(Ti₂Nb)Fe₃O_21+δ, and Bi₇(Ti₂Mg)Fe₃O_21−δ nanoparticles present an indirect allowed transitions with band energies of 2.04, 2.03, and 2.02 eV, respectively. The hybridized (O2p+Fet_2g+Bi6s) formed the valence band (VB) and electronic components of (Ti–3d+Fe–e_g) formed the conduction band (CB) of this six-layered Aurivillius bismuth ferrititanate. The three samples showed efficient photocatalytic degradation of Rhodamine B (RhB) dyes with the excitation wavelength λ > 420 nm. The optical absorption, photodegradation, and magnetic abilities were improved through microstructural modification on “B” site via partial substitution of Mg²⁺ and Nb⁵⁺ for Ti⁴⁺. The photocatalytic results were discussed based on the layer structure and multivalent Fe ions. Fe^3+/2+ in the perovskite slabs (Bi₅Fe₃Ti₃O₁₉)²⁻ could act as the catalytic mediators in the photocatalysis process. As a photocatalyst, Aurivillius Bi₇(Ti₂Mg)Fe₃O_21−δ nanoparticle is advantageous due to its photocatalytic and magnetically recoverable abilities.     

Effects of Ho and Ti Doping on Structural and Electrical Properties of BiFeO3 Thin Films

Effects of Ho and Ti ions individual doping and co‐doping on the structural, electrical, and ferroelectric properties of the BiFeO₃ thin films are reported. Pure BiFeO₃, (Bi_0.9Ho_0.1)FeO₃, Bi(Fe_0.98Ti_0.02)O_3+δ, and (Bi_0.9Ho_0.1)(Fe_0.98Ti_0.02)O_3+δ thin films were prepared on Pt(111)/Ti/SiO₂/Si(100) substrates by using a chemical solution deposition method. All thin films were crystallized in distorted rhombohedral structure containing no secondary or impurity phases confirmed by using an X‐ray diffraction study. Changes in microstructural features, such as grain morphology and grain size distribution, for the doped samples were analyzed by a scanning electron microscopy. From the experimental results, a low electrical leakage (1.2 × 10^?5 A/cm² at 100 kV) and improved ferroelectric properties, such as a large remnant polarization (2P_r) of 52 μC/cm² and a low coercive field (2E_c) of 886 kV/cm, were observed for the (Bi_0.9Ho_0.1)(Fe_0.98Ti_0.02)O_3+δ thin film. Fast current relaxation and stabilization observed in the (Bi_0.9Ho_0.1)(Fe_0.98Ti_0.02)O_3+δ imply effective reduction and neutralization of charged free carriers.     

The Influence of the Precursor on the Formation of Bi2O3 Polymorphs in CSD‐Derived Thin Films

This work examines the synthesis and characterization of crack‐free, β‐Bi₂O₃ thin films prepared on Pt/TiO₂/SiO₂/Si or corundum substrates using the sol‐gel method. We observed that the Bi‐based precursor has a pronounced influence on the β‐Bi₂O₃ phase formation. Well‐crystallized, single β‐Bi₂O₃ thin films were obtained from Bi‐2ethylhexanoate at a temperature of 400°C. In contrast, thin films deposited from Bi‐nitrate and Bi‐acetate resulted in non‐single Bi₂O₃ phase formation. TEOS was used for the stabilization of the β‐Bi₂O₃ phase. The phase composition of the thin films was characterized by means of X‐ray diffraction (XRD), whereas the morphology and thickness of the thin films were studied using scanning electron microscopy (SEM). The β‐Bi₂O₃ films' dielectric properties were characterized utilizing microwave‐frequency measurement techniques: (1) the split‐post dielectric resonator method (15 GHz) and (2) the planar capacitor configuration (1–5 GHz). The dielectric constant and dielectric loss measured at 15 GHz were 257 and 7.5 × 10^?3, respectively.     

Conduction in Bi2O3-based oxide ion conductors under low oxygen pressure. I. Current blackening of the Bi2O3-Y2O3 electrolyte

The cathodic current blackening of Bi₂O₃-based oxide ion conductors was examined for the Bi₂O₃-Y₂O₃ electrolyte at low oxygen pressure. In air, more than 500 mA cm^–2 d.c. could be passed at 600° C without causing changes in the electrolyte itself. However, in argon gas, a limiting current of 3 mA cm^–2 was observed and the electrolyte was blackened at the cathode side. The limiting current was ascribed to control by the diffusion of oxygen gas at the cathode. The blackened oxide was found to consist of a mixture of Bi metal and Bi₂O₃-Y₂O₃ solid solution and to exhibit the equilibrium oxygen partial pressure almost corresponding to that of the Bi, Bi₂O₃ mixture.     

Characterization of Bi2O3 thin films for doping photoluminescent Er3+ ions

Undoped and Er³⁺-doped Bi₂O₃ thin films were sputter-deposited on Si(100) substrates. Sufficiently oxidized Bi₂O₃ films with refractive indices between 2.17?2.23 were obtained at a wavelength of 633 nm; these values are comparable to those of bulk Bi₂O₃ crystals. While the film composition was stable for deposition temperatures between room temperature (RT) and 450 °C, the refractive index steeply decreased above 450 °C and reached 1.4 at 600 °C. The lowering of the optical transmittance spectra indicated aggregation of metallic Bi and darkening of the film. All films exhibited X-ray diffraction patterns of α-Bi₂O₃. The direct and indirect bandgap energies derived from the Tauc plots were 3.4–3.7 eV and 1.9–2.5 eV, respectively, depending on the O₂ flow rate and deposition temperature. Upon excitation of Er³⁺-doped Bi₂O₃ films at 532 nm, Er³⁺ emissions peaking at 1537 and 1541 nm appeared, and the photoluminescence spectra included fine structures reflecting crystal-field splitting. Resonant excitation of Er³⁺ 4f levels and indirect excitation via the defect levels of Bi₂O₃ followed by energy transfer to Er³⁺ contributed to the emission. The films deposited at RT with Er concentrations of 2 at.% had the emission intensity of Er³⁺, but concentration quenching strongly suppressed the Er³⁺ emission because the doped Er³⁺ ions stayed inside the Bi₂O₃ crystals. At deposition temperatures above 400 °C, the concentration quenching was mitigated possibly because out-diffusion of Er³⁺ ions reduced the effective number of Er³⁺ ions in the Bi₂O₃ crystalline domains.     

Kinetic analysis of electrosorption using fast Fourier transform electrochemical impedance spectroscopy: underpotential deposition of Bi in the presence of coadsorbing ClO4 on gold

We demonstrate a relatively simple method for studying various kinetic aspects of metal electrodeposition in the presence of coadsorbing anions on an electrode surface. This method combines cyclic voltammetry (CV) with fast Fourier transform electrochemical impedance spectroscopy (FFT-EIS), where both steady state and transient behaviors of the interface are probed simultaneously. As a model surface reaction, we use electrodeposition of Bi³⁺ in the presence of ClO₄⁻ adsorption from an aqueous solution onto a gold electrode. The voltage range for underpotential deposition (UPD) of Bi³⁺ is determined with potential step (PS) experiments. The voltage dependent UPD coverage of Bi on Au is determined by analyzing the CV data. The relevant kinetic parameters of both Bi³⁺ and ClO₄⁻ deposition reactions under the conditions of CV are measured with FFT-EIS, and analyzed using a complex nonlinear least square method. The differences and similarities between the electrosorption characteristics of Bi³⁺ and ClO₄⁻ on Au are discussed in terms of these kinetic parameters.     

Red-emitting enhancement of Bi4Si3O12:Sm3+ phosphor by Pr3+ co-doping for White LEDs application

In this account, Bi₄Si₃O₁₂:Sm³⁺ and (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) red phosphors were prepared by solution combustion method fueled by citric acid at 900 °C for 1 h. The effects of co-doping Pr³⁺ ions on red emission properties of Bi₄Si₃O₁₂:Sm³⁺ phosphors, as well as the mechanism of interaction between Sm³⁺ and Pr³⁺ ions were investigated by various methods. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) revealed that smaller amounts of doped rare earth ions did not change the crystal structure and particle morphology of the phosphors. The photoluminescence spectroscopy (PL) indicated that shape and position of the emission peaks of (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) phosphors excited at λ_ex=403 nm were similar to those of Bi₄Si₃O₁₂:Sm³⁺ phosphors. The strongest emission peak was recorded at 607 nm, which was attributed to the ⁴G_5/2→⁶H_7/2 transition of the Sm³⁺ ion. The photoluminescence intensities of Bi₄Si₃O₁₂:Sm³⁺ phosphors were significantly improved by co-doping with Pr³⁺ ions and were maximized at Sm³⁺ and Pr³⁺ ions doping concentrations of 4 mol% and 0.1 mol%, respectively. The characteristic peaks of Sm³⁺ ions were displayed in the emission spectra of (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) phosphors excited at respectively λ_ex=443 nm and λ_ex=481 nm (Pr:³H₄→³P₂, ³H₄→³P₀). This indicated the existence of Pr³⁺→Sm³⁺ energy transfer in (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) phosphors.     

Gibbs free energy of formation of Bi2O3 from EMF cells with δ-Bi2O3 solid electrolyte

Determination of thermodynamic data on the formation of Bi₂O₃ was established by emf measurements as a function of temperature in the range 660–820°C on the system Metal, Bi(1)|Bi₂O₃|Pt, O₂. From the results using a tungsten electrode the following relation was found: ΔG⁰ = ?(134.7 ± 1.2) + (64.0 ± 1.2) × 10^?3 T kcal mole^?1 (validity range: 940–1080 K). Standard thermodynamic data at 298 K were calculated as ΔG⁰ = ?119.2 ± 2.1 kcal mole^?, ΔH⁰ = ?139.0 ± 1.2 kcal mole^?1, and ΔS⁰ = ?66.3 ± 1.2 eu.     

Construction of a novel Ca2Bi2O5/α-Bi2O3 semiconductor heterojunction for enhanced visible photocatalytic application

Bi³⁺-containing compounds have been intensively investigated for their potential application as photocatalysts for degrading pollutants and splitting water. In this work, a Ca₂Bi₂O₅/α-Bi₂O₃ heterojunction photocatalyst was successfully prepared via the facile sol–gel method. The excess of the initial Bi raw material can result in the Ca₂Bi₂O₅/α-Bi₂O₃ heterojunction of the final products. The as-synthesized nanoparticles were investigated via X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive spectrometry, UV–Vis optical absorption, and X-ray photoelectron spectroscopy. The band energy of the Ca₂Bi₂O₅ substrate semiconductor was 2.49 eV and characterized with a direct transition nature. The photocatalytic effect on the photodegradation of Rhodamine B solutions was evaluated. Ca₂Bi₂O₅/α-Bi₂O₃ heterojunctions showed improved photocatalytic abilities compared with single Ca₂Bi₂O₅ and α-Bi₂O₃ under viable light irradiation. The mechanism was discussed in terms of the microstructure, luminescence intensities, and decay curves (lifetimes). The photo-produced electrons and holes can be adequately separated in Ca₂Bi₂O₅/α-Bi₂O₃ heterojunctions ensuring its photocatalytic activities. The present results can serve as reference for investigating the optical properties of Bi semiconductors.     

Low‐Temperature Dielectric Relaxations Associated with Mixed‐Valent Structure in Na0.5Bi0.5Cu3Ti4O12

We, herein, present comparative investigations on the Na_0.5Bi_0.5Cu₃Ti₄O₁₂ ceramic samples with and without 10 mol% excess of Na/Bi. The samples were prepared by the standard solid‐state reaction technique. The dielectric properties of the sample were investigated in the temperature (93–320 K) and frequency (20 Hz–10 MHz) windows. Three thermally activated dielectric relaxations observed in Na_0.5Bi_0.5Cu₃Ti₄O₁₂ with the activation energies of 0.104, 0.267, and 0.365 eV for the low‐, middle‐, and high‐temperature dielectric relaxations, respectively. Only the low‐temperature relaxation was observed in both Na and Bi excessive samples. X‐ray photoemission spectroscopy results revealed the mixed‐valent structures of Cu⁺/Cu²⁺ and Ti³⁺/Ti⁴⁺ in Na_0.5Bi_0.5Cu₃Ti₄O₁₂ sample, but only Ti³⁺/Ti⁴⁺ in Na and Bi excessive samples. Our results showed that the dielectric properties of the investigated samples are strongly linked with these mixed‐valent structures. The high‐ and low‐temperature relaxations were attributed to be a polaron‐type relaxation due to localized carriers hopping between Cu⁺/Cu²⁺ and Ti³⁺/Ti⁴⁺, respectively. The middle‐temperature relaxation is suggested to be a dipole‐type relaxation caused by the defect complex of bismuth and oxygen vacancies.     

Bi4Ti3O12 nanoparticles prepared by hydrothermal synthesis

The influence of hydrothermal conditions (including starting materials, reaction temperature and time) on the crystal structure and the morphology of Bi₄Ti₃O₁₂ particles are discussed in this paper. Bi₄Ti₃O₁₂ nanocrystalline particles were hydrothermally synthesized at temperatures in the range of 180–230 °C for 4–12 h, from Bi(NO₃)₃·5H₂O, TiCl₄ and NaOH solution. The XRD results revealed that a typical bismuth layered perovskite structure Bi₄Ti₃O₁₂ was obtained. The TEM showed that the Bi₄Ti₃O₁₂ nanoparticles are tabular, and the sizes are about 200 nm.     

Synthesis,structural characterization,and photocatalytic activity of Bi‐based nanoparticles

Bi‐based nanoparticles were successfully synthesized (500°C/2 h) following two intermediate‐temperature routes, Pechini and a combined method of mechanical milling/molten salts. Herein, α‐Bi₂O₃/Bi₂O₂CO₃ heterostructures were identified. These types of heterostructures have shown advantages to improve the visible light responsive activity of Bi‐based nanoparticles to facilitate the separation of photogenerated electron‐hole pairs. By fixing the experimental parameters, the synthesis route and Ag contents showed to play a very important role in the phase composition of the Ag‐containing samples; the formation of Bi/Ag‐Bi₂O₃/Bi₂O₂CO₃ and Ag/Ag‐Bi₂O₃/Bi₂O₂CO₃ complex hybrid structures were revealed. The α‐Bi₂O₃/Bi₂O₂CO₃ heterostructure prepared by combined method exhibited higher photocatalytic efficiency (66.84%) for degrading methylene blue (MB) depending on Bi₂O₂CO₃ component proportion. For the Ag‐containing hybrid structures, the performance of their catalytic activity did not show an increase with respect to α‐Bi₂O₃/Bi₂O₂CO₃. However, in these samples, the degradation efficiency was slightly enhanced with the efficient doping of Ag into the α‐Bi₂O₃ structure and the existence of Bi when the Pechini method was used. Also, a possible photocatalytic process for degrading MB is presented.     

Dielectric Properties of Glasses in the Systems Bi2O3-CdO-SiO2, Bi2O3-CdO-B2O3, and Bi2O3-CdO-GeO2 and Their Relation to the Structure of Glass

Areas of glass formation and regions of “neo-ceramic” glasses in the systems Biz03-CdO-Si02, Bi203-Cd0-B203, and Bi203-Cd0-GeO2 are demarcated. Properties of glasses in the neoceramic regions were determined before and after nucleation and heat treatment. There are no maxima or minima in the dielectric properties versus composition curves. The dielectric constants increase after nucleation and heat treatment. The dissipation factors show a remarkable change toward higher values. Transparent glasses with Bi₂O₃. CdO as the predominant constituents have unusual dielectric constants ranging from 30 to 42 and dissipation factors ranging from 3 to 50 × 10⁻⁴., Since these glasses contain only from 0.5 to 2.0 wt% SiO₂ or B₂O₃ or 5 wt% GeO₂, the conventional concept of glass structure composed of a random spacial network of SiO₄ tetrahedra, whose interstices are filled with network modifiers, cannot be sustained in this case. It is suggested that the dominant cations Bi^{3 +} and Cd²⁺ form the network and that the interstices are occupied by Si4 + cations. The function of the Si⁴⁺ ion apparently is to distort the highly polarizable Bi3 + ion enough to form a random network. It appears to be possible that Bi³⁺ and Cd²⁺ can form the network in sixfold coordination. The dielectric losses observed are explained in terms of the relative instability of the structure.     

A sintering strategy for lithium zinc ferrite with a high saturation magnetization and low ferromagnetic resonance line-width

Based on the activation energy and diffusion kinetics theory of grain growth, Li_0.42Zn_0.28Ti_0.1Fe_2.2O₄ ceramics with a low ferromagnetic resonance line-width (ΔH) and high saturation magnetization (Ms) were synthesized by adopting LTCC (low-temperature cofired ceramics) technology. The critical sintering temperature of ferrite synthesis was reduced to 925 °C due to activation energy reduction and the liquid phase sintering mechanism of Bi₂O₃. The sintering agent B₂O₃ further improved the grain size, homogeneity, density and properties. EDS and XRD refinement showed that Bi³⁺ and B³⁺ ions did not enter lattices, but Ti⁴⁺ ions entered lattices and replaced part of the Fe³⁺ ions, leading to the lattice expansion. Finally, homogeneous and compact Li_0.42Zn_0.28Ti_0.1Fe_2.2O₄ ferrite with Ms up to 354.6 kA/m and ΔH as low as 184.2 Oe was synthesized at temperatures as low as 925 °C by adding an appropriate content of Bi₂O₃ and B₂O₃. In the present study, the exploration and practice of reducing the sintering temperature and improving the material properties based on sintering agents is a beneficial supplement and improvement to the wider application of the LTCC technique.