Composition Bi Research Articles

Microstructure evolution and thermoelectric behaviour of directionally solidified Bi2Te3 based multiphase thermoelectric

Thermoelectric materials are vital for sustainable energy applications, yet improving their efficiency remains a significant challenge. This study investigates the influence of unidirectional solidification on the Bi2Te3-Cu3Te2 eutectic alloy to enhance thermoelectric performance through microstructural control. Alloys of the same composition of Bi, Cu, and Te were processed using a Bridgman-type furnace under varying solidification velocities, with the resulting phases characterized as rhombohedral (Bi2Te3) and tetragonal (Cu3Te2). A distinctive eutectic columnar structure was formed at higher solidification rates, optimizing the balance between electrical and thermal transport. Alloy Solidified at 20µm/s, exhibited a peak figure of merit (zT) of 0.93 at 442K due to improved power factor and reduced thermal conductivity. This work highlights unidirectional solidification as an effective approach to advancing thermoelectric material design.

Structural, optical absorption and electrical characteristics of sol-gel synthesized chromium-doped bismuth ferrites

Multiferroic materials have remarkable and several technical uses such as random-access multi-state memories, solar cell devices, data storage recording technologies, etc. An attempt has been made here to synthesize chromium-doped Bi(Fe1-xCrx)O3 (x = 0–0.10) oxides via citrate based sol-gel route and characterized with regards to structural, optical absorption and electrical properties. It depicts a rhombohedral structure with space group R3c for BiFeO3 and Bi(Fe0.98Cr0.02)O3 compositions. The lattice parameters for BiFeO3 on rhombohedral axes are aR ∼5.796 Å, α ∼59.34° which decreases linearly with chromium (x). Similarly, the parameters on hexagonal axes also decrease as aH ∼5.739–5.730 Å, and cH ∼14.269–14.262 Å. However, chromium doping causes a drop in crystallite size and rise in dislocation density. The absorption spectra show a broad peak at λ = 392 nm (for x = 0) and a broader as well as high intense peak for x = 0.02 (λ∼ 393 nm) which is attributed to charge transfer transitions from O2− (2p) valence band to Fe -3d (eg and t2g split levels) conduction band. Band at λ ∼310 nm is associated to the band gap (Eg) of material. Composition Bi(Fe0.98Cr0.02)O3 (x = 0.02) exhibits the highest values of the dielectric constant (εr ∼ 1102), loss (tan δ ∼ 1.1), and least value of impedance. The Cole-Cole plot depicts a depressed semi-circle and indicates presence of loss due to grains only. The room temperature P–E hysteresis loop with remanent polarization (Pr = 0.11439 μC/cm2) and leakage current density (J = 1.1 μA/cm2) are found maximum for Bi(Fe0.98Cr0.02)O3 (x = 0.02). The I-E loop and frequency-dependent P-E loops depict ferroelectric nature of all compositions. The analysis of leakage current density and slope values infer the presence of space charge limited conduction (SCLC) mechanism. These findings suggest materials applications in recent technologies.

Critical current density of high-temperature superconducting ceramics BSCCO Bi-2223

In the paper the results of the study on the synthesis of high-temperature superconducting ceramics of nomi- nal composition Bi1.6Pb0.4Sr2Ca2Cu3Oy by various methods were presented based on amorphous phases using glass-ceramic technology and solid-phase method. For comparison, amorphous phases were obtained in two ways. In the first case, a heating furnace of a special design was developed to obtain an amorphous phase, which provides melting without using a crucible. The heating of the initial samples for melting is carried out due to the combined effect of the convection heat flux and the radiation of heating elements, which consists of the IR region of the spectrum at a melting temperature in the spectral range of 1300–1350 nm. In the se- cond case, melting is carried out under the influence of broadband optical radiation, including UV, visible and IR spectral regions. The production of glassy precursors is carried out by draining the melt onto a quenching device in the form of a propeller made of stainless steel. Studies of the formation rate of the superconducting high-temperature phase Bi-2223 were carried out in the same temperature conditions at 848–850 °C with in- termediate grinding every 24 hours and the study of the phase composition by X-ray diffraction method. Studies showed that the glass phase-based method ensures the completeness of the formation of the high- temperature phase Bi-2223 and the rate of its formation is significantly higher than by the solid-phase method (2.5–3 times). Studies of the critical density of the transport current have shown that the current value is 7.05×103 mA/cm2, (measured by the criterion of 1 µV/cm), which is significantly higher compared to other methods.

Synthesis and NEXAFS and XPS Characterization of Pyrochlore-Type Bi1.865Co1/2Fe1/2Ta2O9+Δ

A cubic pyrochlore with the composition Bi1.865Co1/2Fe1/2Ta2O9+Δ (space group Fd-3m, a = 10.5013(8) Å) was synthesized from oxide precursors using solid-phase reactions. These ceramics are characterized by a porous microstructure formed by randomly oriented grains of an elongated shape with a longitudinal size of 0.5–1 µm. The electronic state of cobalt and iron ions in oxide ceramics was studied by NEXAFS and XPS spectroscopy. The parameters of the XPS spectra of Bi4f, Bi5d, Ta4f, Co2p, and Fe2p ionization thresholds for a complex pyrochlore were compared with the parameters of the corresponding oxides of the transition elements. The energy position of the XPS-Ta4f and -Ta5p spectra is shifted towards lower energies compared to the binding energy in tantalum(V) oxide by 0.75 eV. According to XPS spectroscopy, bismuth and tantalum cations have the corresponding effective charge of +3 and +(5-δ). The NEXAFS-Fe2p spectrum of ceramics coincides with the spectrum of Fe2O3 in its main spectrum characteristics and indicates the content of iron ions in the oxide ceramics in the form of octahedral Fe(III) ions, and according to the character of the Co2p spectrum, cobalt ions are predominantly in the Co(II) state.

High-performance Bi2O3 nanoflakes for advanced energy storage applications

In this work, Bi2O3 nanoflakes (NFs) were synthesized using the co-precipitation method. To understand the crystal structure-surface morphology and their functional properties such as optical band-gap energy, specific capacitance and magnetic properties are examined by various analytical techniques including X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), High-Resolution Transmission Electron Microscopy (HRTEM), Vibrating Sample Magnetometer (VSM), UV–Visible Diffuse Reflectance Spectroscopy (UV-DRS), X-ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy, and Cyclic Voltammetry (CV). FE-SEM confirmed the formation of the nanoflakes, while HRTEM verified their monoclinic crystal structure and provided details on the orientation of the lattice planes. XRD result showed distinctive peaks corresponding to the α-phase, indicating a crystallite size of 8.21 nm. Raman and XPS results are also demonstrated formation of the Bi2O3 NFs with their signature bands. VSM analysis revealed the presence of both magnetic and nonmagnetic phases in the Bi2O3 NFs. Optical studies indicated a promising band gap of 1.9 eV, suggesting potential for optoelectronic applications. Surface analysis confirmed the composition of Bi+ and O2− in the NFs. Additionally, electrochemical assessments through CV demonstrated a significant specific capacitance of 537 F/g at 20 mV/s. Nyquist plot analysis suggested an equivalent circuit R(CR)(CR), indicating an optimal fit. Furthermore, we have made the systematic comparison of optical band gap energy of Bi2O3 with reported different nanostructures such as Peanut, needles, rod and flakes and found that the present study nanoflakes offer much lower band energy compared to above mentioned all other morphologies. Due to the obtained lower energy band gap and specific capacitance performance of the Bi2O3 NFs, it is strongly suggested to the advanced energy storage applications.

Controlling the composition and elemental distribution of bi- and multi-metallic nanocrystals via dropwise addition

Controlling the composition and elemental distribution of bi- and multi-metallic nanocrystals via dropwise addition

Synthesis OF Bi<sub>1.5</sub>CoSb<sub>1.5</sub>O<sub>7</sub> pyrochlore under hydrothermal conditions and its catalytic properties in the CO oxidation

The pyrochlore solid solution region in the Bi2O3–CoO–Sb2O5 system is determined. A previously unknown ternary oxide Bi3Co2/3Sb7/3O11 with cubic KSbO3 structure (sp. gr. Pn-3, a = 9.5801(1) Å, wR =0.0132) is found. An isothermal section of the system is constructed in the region of CoO-Bi3SbO7-CoSb2O6-BiSbO4 at 650°C. It is shown that cobalt state in pyrochlore crystal lattice is Co2+. For pyrochlore composition Bi1.5CoSb1.5O7, the synthetic methods under hydrothermal conditions of both without microwave-assisted treatment and with it have been developed. Based on the data of X-ray diffraction analysis, local energy-dispersive X-ray analysis, scanning microscopy and IR spectroscopy, a mechanism for the pyrochlore phase formation under hydrothermal condition is proposed. The dispersed Bi1.5CoSb1.5O7 samples (SCD = 30 nm) are synthesized and the prospects of their use as catalysts for CO oxidation are shown.

Investigation on the Thermal and Wettability Properties Aided with Mechanical Test Simulation of Tin (Sn) - Bismuth (Bi) Solder Alloy at Low Reflow Temperatures

The current study proposes to investigate the thermal, wettability and mechanical properties of a low temperature SnBi solder. The main aim is to investigate the performance of the SnBi solder alloy with different Bi composition. The study also establishes the relationship between melting temperature, spreading area and tensile stress of the SnBi with different Bi composition at different low reflow temperatures. The thermal and wettability tests are conducted experimentally, while the mechanical test will be analysed via finite element analyses (FEA). The single shear lap test method was adopted for the simulation. The thermal properties of the SnBi solder are investigated using the differential scanning calorimeter (DSC). The reflow temperature selected ranges from 160 °C to 220 °C to accommodate the purpose of low temperature soldering. Wetting test results showed that spreading area of Sn48Bi solder alloy increased to 28.1 and 42.88 at 180 °C and 210 °C respectively. The increase in the Bi composition reduced the tensile strength regardless of the increase of the reflow temperature. The preliminary results commend the characteristics of the SnBi solder as a possible alternative to the Pb solder.

Characterized on hydrogen properties and mechanism of Al–Sn–Bi composite powder in salt solutions

Using low-melting point elements to promote the Al/H2O reaction has garnered considerable attention because it is an economical approach to hydrogen supply. Herein, .Al–Sn–Bi composite powder was prepared through milling. The Al–Sn–Bi composite powder and the hydrolysate were investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the hydrolysis products is primarily AlOOH. The properties of the Al/H2O reaction were systematically characterized in salt solutions. Results show that the presence of Sn and Bi is beneficial to achieve short introduction times and large Al/H2O reaction rates. The hydrogen generation rate of the Al–Sn–Bi composite is 4566 mL min−1 g−1 and 3600 mL min−1·g−1 with NaCl and Na2SO4 solutions, respectively and the hydrogen production efficiency can reach 100% in 1 min. Additionally, the mechanism of Sn and Bi promoting Al/H2O reaction was characterized by density functional theory (DFT) calculations. The DFT calculations show that Sn and Bi replace 1/8 ML, 1/4 ML and 1/2 ML surface atoms of Al (111), the surface chemical potential increases with increasing doping concentration, and the electrode potential decreases with increasing doping concentration. The presence of Sn and Bi increases the surface chemical potential and reduces the electrode potential, this is conducive to the microcell reaction and promotes the Al/H2O reaction.

Carrier mobility dependence of indium antimonide-bismide on carrier concentration, temperature, and bismuth composition grown on semi-insulating gallium arsenide substrate

We explore the impact of carrier concentration, temperature, and bismuth (Bi) composition on the carrier mobility of indium antimonide-bismide (InSb1−x Bi x ) material. Utilizing the molecular beam epitaxy method, we achieved high Bi composition uniformity. This method also enables the InSb1−x Bi x to be grown on semi-insulating GaAs substrate, effectively preventing parallel electrical conduction during Hall effect measurement. Our findings reveal that InSb1−x Bi x doped with silicon (Si) and tellurium (Te) consistently exhibit n-type conductivity. In contrast, InSb1−x Bi x doped with beryllium (Be) exhibit a transition from n to p type conductivity, subjected to the Be doping level and the measurement temperature. Based on these observations, we proposed an empirical model describing the dependence of InSb1−x Bi x electron mobility on carrier concentration, temperature, and Bi composition, specifically for Si and Te-doped InSb1−x Bi x samples. These insights gained from this study hold potential application in photodetector device simulations.

Layered rare-earth stabilized Bi2O3: Organic amines intercalation under ambient conditions and their role as a solid adsorbent for iodine

Intercalation chemistry is pivotal in discovering the dimension-dependent properties of 2D materials and expanding their applications. Layered bismuth oxide with composition Bi0.775Ln0.225O1.5 (Ln = La, Pr, Nd, Sm, and Eu) has been demonstrated to intercalate both aliphatic and aromatic amines, resulting in the unit cell expansion along the c-axis. Aliphatic amines were present in a vertical orientation, whereas aromatic amines preferred a horizontal orientation. The intercalated amine concentrations ranged from 0.15 to 0.54 mole per mole of the host. Among the chosen amines, ethylenediamine intercalation enhanced the c-axis of Bi0.775Pr0.225O1.5 by 20 Å, justified by the high amounts of intercalant and intermolecular hydrogen bonding between them, resulting in a bilayer arrangement. The lamellar-plate-like morphology filled with intercalants and twinning collapse was noticed in the FESEM and SAED patterns after the intercalation process. The ethylenediamine intercalated Bi0.775Pr0.225O1.5 was further evaluated for iodine adsorption from non-aqueous solutions through chemisorption following pseudo-second-order kinetics. The X-ray diffraction peaks after adsorption suggested bilayer to monolayer transformation aided by chemical alterations within the host's van der Waals gaps. The N–I vibration mode, observed in the FTIR spectrum of the iodine-adsorbed sample, further augmented the interaction between the two during adsorption.

Photovoltaic Effect of La and Mn Co-Doped BiFeO3 Heterostructure with Charge Transport Layers.

Bismuth ferrite BiFeO3 (BFO)-based ferroelectrics have great potential as inorganic perovskite-like oxides for future solar cells applications due to their unique physical properties. In this work, La and Mn co-doped BFO thin films with compositions Bi0.9La0.1(Fe1-xMnx)O3 (x = 0, 0.05, 0.1, 0.15) (denoted as BLF, BLFM5, BLFM10, BLFM15, respectively) were prepared via a sol-gel technique on indium tin oxide (ITO) glass. All the films are monophasic, showing good crystallinity. The optical bandgap Eg was found to decrease monotonously with an increase in the Mn doping amount. Compared with other compositions, the BLFM5 sample exhibits a better crystallinity and less oxygen vacancies as indicated by XRD and XPS measurements, thereby achieving a better J-V performance. Based on BLFM5 as the light absorbing layer, the ITO/ZnO/BLFM5/Pt and ITO/ZnO/BLFM5/NiO/Pt heterostructure devices were designed and characterized. It was found that the introduction of the ZnO layer increases both the open circuit voltage (Voc) and the short circuit current density (Jsc) with Voc = 90.2 mV and Jsc = 6.90 μA/cm2 for the Pt/ BLFM5/ZnO/ITO device. However, the insertion of the NiO layer reduces both Voc and Jsc, which is attributed to the weakened built-in electric field at the NiO/BLFM5 interface.

Influences of oxygen partial pressure on the phase composition of the (Bi, Pb)-2212 precursor powder

Bi-2223 tapes, synthesized through the two-powder method, exhibit distinctive features such as high current density and a controllable secondary phase. Traditionally, the two-powder method involves the separate preparation of Bi-2212 and CaCuO powders followed by their mixing. However, during this process, it is necessary to dope the Bi-2212 powder with an appropriate Pb content to achieve a stable lattice structure in the Bi-2223 phase. The alteration of ion valences between Pb2+ and Pb4+ influences the oxygen content, thereby affecting the phase formation of (Bi, Pb)-2212 and, consequently, the final properties of Bi-2223 tapes. Surprisingly, limited research has explored the impact of the heat treatment process on (Bi, Pb)-2212. Consequently, this study investigates the phase composition and microstructure of (Bi, Pb)-2212 under various oxygen partial pressures to deepen our understanding of the effect of Pb on the composition of (Bi, Pb)-2212. Simultaneously, the behavior of Pb in the lattice of Bi-2212 is analyzed. Ultimately, the findings reveal that low oxygen conditions are advantageous for fabricating (Bi, Pb)-2212 powder with a high main phase content and a reduced secondary phase, thereby demonstrating excellent current-carrying performance in Bi-2223 tapes.

Mono-, bi- and tri-metallic Fe-based platinum group metal-free electrocatalysts derived from phthalocyanine for oxygen reduction reaction in alkaline media.

In this manuscript, a comprehensive study is presented on Fe-based electrocatalysts with mono, bi, and tri-metallic compositions, emphasizing the influence of processing-structure correlations on the electrocatalytic activity for the oxygen reduction reaction (ORR) in the alkaline medium. These electrocatalysts were synthesized through the mixing of transition metal phthalocyanines (TM-Pc) with conductive carbon support, followed by controlled thermal treatment at specific temperatures (600 °C and 900 °C). An extensive analysis was conducted, employing various techniques, including X-ray Absorption Spectroscopy (XAS), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD), providing valuable insights into the structural characteristics of the synthesized nanoparticles. Importantly, an increase in the Fe-Pc weight percentage from 10% to 30% enhanced the ORR activity, although not proportionally. Furthermore, a comparative analysis between mono, bi, and tri-metallic samples subjected to different functionalization temperatures highlighted the superior electrocatalytic activity of electrocatalysts functionalized at 600 °C, particularly Fe 600 and Fe-Ni-Cu 600. These electrocatalysts featured Eon values of 0.96 V vs. RHE and E1/2 values of 0.9 V vs. RHE, with the added benefit of reduced anionic peroxide production. The potential of these Fe-based electrocatalysts to enhance ORR efficiency is underscored by this research, contributing to the development of more effective and sustainable electrocatalysts for energy conversion technologies.

High-Entropy Lead-Free Perovskite Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 Powders and Related Ceramics: Synthesis, Processing, and Electrical Properties.

A novel high-entropy perovskite powder with the composition Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 was successfully synthesized using a modified Pechini method. The precursor powder underwent characterization through Fourier Transform Infrared Spectroscopy and thermal analysis. The resultant Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 powder, obtained post-calcination at 900 °C, was further examined using a variety of techniques including X-ray diffraction, Raman spectroscopy, X-ray fluorescence, scanning electron microscopy, and transmission electron microscopy. Ceramic samples were fabricated by conventional sintering at various temperatures (900, 950, and 1000 °C). The structure, microstructure, and dielectric properties of these ceramics were subsequently analyzed and discussed. The ceramics exhibited a two-phase composition comprising cubic and tetragonal perovskites. The grain size was observed to increase from 35 to 50 nm, contingent on the sintering temperature. All ceramic samples demonstrated relaxor behavior with a dielectric maximum that became more flattened and shifted towards lower temperatures as the grain size decreased.

Isovalent co-alloying contributes to considerable improvement in thermoelectric performance of BiSe bulks with weak anisotropy

BiSe with intrinsic low thermal conductivity has considered as a promising thermoelectric (TE) material at nearly room temperature. To improve its low thermoelectric figure of merit (zT), in this work, Sb and Te isovalent co-alloying was performed and significantly optimized its TE property with weakly anisotropic characteristic. After substituting Sb on Bi sites, the carrier concentration is suppressed by introduction of Sb Se site defects, which contributes to the increased absolute value of Seebeck coefficient (|S|). Further co-alloying Te on Se of the optimized composition Bi0.7Sb0.3Se, the carrier concentration increased without affecting the |S| due to the enhanced effective mass, which leads to a highest power factor of 12.8 μW/(cm·K2) at 423 K. As a result, a maximum zT of ∼0.54 is achieved for Bi0.7Sb0.3Se0.7Te0.3 along the pressing direction and the average zT (zTave) (from 300 K to 623 K) are drastically improved from 0.24 for pristine BiSe sample to 0.45. Moreover, an energy conversion efficiency ∼4.0% is achieved for a single leg TE device of Bi0.7Sb0.3Se0.7Te0.3when applied the temperature difference of 339 K, indicating the potential TE application.

Novel synthesis of stabilized Bi1–x–yGdxDyyO1.5 solid electrolytes with enhanced conductivity for intermediate temperature solid oxide fuel cells (SOFCs)

Herein, we report the synthesis of a Dy–Gd co-doped cubic phase-stabilized Bi2O3 solid electrolyte system via solid-state processing under atmospheric conditions. Doping with Dy3+ and Gd3+ has been observed to significantly enhance the densification process during sintering for stabilization purposes, thereby improving the electrical properties of δ-Bi2O3-type polymorphs. The synthesized ceramics were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy-energy dispersive X-ray spectroscopy (FESEM-EDX), thermal gravimetry/differential thermal analysis (TG/DTA), and the four-point probe technique (4PPT). XRD analysis reveals that the samples Bi1–x–yGdxDyyO1.5 (y = 0.05/x = 0.05, 0.10, 0.15, and 0.20, and x = 0.05/y = 0.10, 0.15, and 0.20) exhibit a stable face-centered cubic δ-phase and a mixed-phase crystallographic structure. The XRD analysis of the stabilized δ-phase suggests that the prepared oxides show a face-centered cubic (FCC) structure with a space group of Fm-3m. FESEM micrographs reveal that the composition Bi0.90Gd0.05Dy0.05O1.5 has no significant holes. Nevertheless, an evident increase in the pore formation is observed as the amount of Gd2O3 increases until it reaches 20%. This finding suggests that dense pellets are formed during the sintering process at 900–1000 °C. The DTA analyses were performed to verify the phase stability, which agrees with the XRD results. The electrochemical performance of the synthesized Dy–Gd co-doped Bi2O3 solid electrolyte system was evaluated and analyzed in detail by using the electrochemical impedance spectroscopy (EIS) technique. Based on EIS and conductivity measurements, Bi0.75Gd0.20Dy0.05O1.5 exhibits the lowest activation energy of 0.519 eV and the highest conductivity value of 0.398 S/cm at 627 °C compared to the other samples; this composition can be used as a solid electrolyte for intermediate-temperature solid oxide fuel cells (SOFCs).

Synthesis and Research of Critical Parameters of Bi-HTSC Ceramics Based on Glass Phase Obtained by IR Heating

In this paper influence of the excess Ca and Cu cations on the critical temperature (Tc) and critical transport current density (Jc) of high-temperature superconducting ceramics of the compositions (HTSC) Bi1.6Pb0.4Sr2Ca2.1Cu3.1Oy, Bi1.6Pb0.4Sr2Ca2.25Cu3.25Oy and Bi1.6Pb0.4Sr2Ca3Cu4Oy synthesized by the glass-ceramic method has been studied. The synthesis of superconducting ceramics was carried out on the basis of the glass phase, obtained by ultra-fast quenching of the melt. Melting of the mixture of starting components was carried out without the use of a crucible under the influence of IR radiant heating. Analysis of the elemental composition of the samples of the initial precursors showed a significant deviation from stoichiometry in oxygen (increase), as well as a decrease in calcium content. The synthesis of HTSC ceramics was carried out at a temperature of 849–850 °C for 96 h with intermediate grinding every 24 h. Studies of the phase composition of ceramic samples by X-ray diffraction have shown that HTSC ceramics consist only of a superconducting high-temperature phase Bi-2223. Studies of current-carrying characteristics by the four-point probe method according to the criterion of 1 µV/cm2 have shown that high-temperature superconducting ceramics of the compositions Bi1.6Pb0.4Sr2Ca2.1Cu3.1Oy, Bi1.6Pb0.4Sr2Ca2.25Cu3.25Oy and Bi1.6Pb0.4Sr2Ca3Cu4Oy have an increased density of critical transport current of 9.12 A/cm2, 7.62 A/cm2 and 7.26 A/cm2, respectively. At the same time, it was found that with a decrease in the content of Ca and Cu cations in HTSC ceramics, an increase in the critical current density is observed.

Unveiling transport properties in rare-earth-substituted nanostructured bismuth telluride for thermoelectric application

Abstract Thermoelectrics is an emerging technology in the field of renewable energy sources, and the exploration of doped materials has opened up new avenues for enhancing their performance. La-doped thermoelectric materials with the composition Bi2−x La x Te3 (x = 0.0, 0.1, 0.2, 0.3, 0.4) were synthesized using the WOWS sol–gel method and sintered at 500 °C for 5 h. X-ray diffraction analysis confirmed a rhombohedral crystal structure with lattice constants of a = b = 4.41(2) Å and c = 29.81(3) Å. Scanning electron microscopy revealed particle-like shapes (0.7–2.5 μm). Fourier transform infrared spectroscopy confirmed the single-phase nature of the samples. DC electrical measurements showed increasing conductivity with temperature. AC electrical analysis demonstrated frequency-dependent behavior with increasing AC conductivity and decreasing loss factor and dielectric constants. Seebeck coefficient measurements exhibited temperature-dependent behavior. Thermal transport properties showed increasing thermal conductivity and volumetric specific heat with temperature, while thermal diffusivity decreased. The composition Bi1.9La0.1Te3 with x = 0.1 doping displayed lower thermal conductivity, higher electrical conductivity, and a higher ZT value, making it more suitable for thermoelectric applications. Furthermore, the sample Bi1.8La0.2Te3 exhibited favorable characteristics for energy storage applications compared to the other samples. These findings provide insights into the potential applications of La-doped bismuth telluride compounds in thermoelectric and energy storage systems.

Effects of conditions on thе synthesis and properties of Bi-2234 HTSC ceramic produced from the melt

The article presents the results of a study aimed at obtaining the formation of superconducting phases and the formation of a high texture of particles that affect the current-carrying characteristics in ceramics of the composition Bi1.6Pb0.4Sr2Ca3Cu4Oy and the study of their properties. For the synthesis of ceramics, precursors from the glass phase were used, which were obtained by melting the starting material under the influence of radiant flux (IR radiation) and quenching the melt in a facility rotating at a speed of 3000 rpm. Platinum wire was used as a substrate. During the heat treatment of samples in the temperature range of 845–850 °C and a holding time of 72 hours (with intermediate grinding every 24 hours), the superconducting high-temperaturephase Bi-2223 crystallized in the studied samples. Critical temperatures and resistances of superconducting samples were measured by the four-probe method by measuring the dependence of resistance on the temperature in the range from 300 K to 60 K.