Bi Doping Research Articles

Enhanced Photocatalytic Activity of Nickel(II)‐Doped Bi2O2CO3 Nanosheets for Efficient Nitric Oxide Removal

AbstractBi2O2CO3 is a typical bismuth‐based semiconductor photocatalyst that has attracted much attention because of layered structure and polarization characteristics. However, the wide bandgap of Bi2O2CO3 limits its practical applications in photocatalysis. In this study, the nickel (II)‐doped Bi2O2CO3 (Ni2+‐Bi2O2CO3) with oxygen vacancies was prepared by adding a controllable amount of nickel ions. The photocatalytic efficiency of the optimized sample for ppb‐grade NO under visible light irradiation is 59.4 %, which is 2.8 times than that of its counterpart, Bi2O2CO3 (21.2 %). Based on experiments and characterizations, Introduction of nickel ions and oxygen vacancies improves the photocatalytic performance of Ni2+‐Bi2O2CO3, which not only lowered the bandgap from 3.25 eV to 2.92 eV, but also reduced the recombination of photogenerated carriers by formation of the impurity level. Furthermore, the adsorption and photocatalytic conversion pathway of NO was explored by in situ DRIFTS, the principal byproducts of photocatalytic oxidation of NO are NO3− and NO2−. This work offers a new perspective to improve the photocatalytic activity by doping mothed for air purification.

Enhancing Thermoelectric Performance of Mg3Sb2 Through Substitutional Doping: Sustainable Energy Solutions via First-Principles Calculations

Mg3Sb2-based materials, part of the Zintl compound family, are known for their low thermal conductivity but face challenges in thermoelectric applications due to their low energy conversion efficiency. This study addressed these limitations through first-principles calculations using the CASTEP module in Materials Studio 8.0, aiming to enhance the thermoelectric performance of Mg3Sb2 via strategic doping. Density functional theory (DFT) calculations were performed to analyze electronic properties, including band structure and density of states (D.O.S.), providing insights into the influence of various dopants. The semiclassical Boltzmann transport theory, implemented in BoltzTrap (version 1.2.5), was used to evaluate key thermoelectric properties such as the Seebeck coefficient, electrical conductivity, electronic thermal conductivity, and electronic figure of merit (eZT). The results indicate that doping significantly improved the thermoelectric properties of Mg3Sb2, facilitating a transition from p-type to n-type behavior. Bi doping reduced the band gap from 0.401 eV to 0.144 eV, increasing carrier concentration and mobility, resulting in an electrical conductivity of 1.66 × 106 S/m and an eZT of 0.757. Ge doping increased the Seebeck coefficient to −392.1 μV/K at 300 K and reduced the band gap to 0.09 eV, achieving an electronic ZT of 0.859 with low thermal conductivity (11 W/mK). Si doping enhanced stability and achieved an electrical conductivity of 1.627 × 106 S/m with an electronic thermal conductivity of 11.3 W/mK, improving thermoelectric performance. These findings established the potential of doped Mg3Sb2 as a highly efficient thermoelectric material, paving the way for future research and applications in sustainable energy solutions.

Structural Modifications due to Bi-Doping in MAPbBr3 Single Crystals and Their Impact on Electronic Transport and Stability.

Doping strategy in lead halide perovskites is essential to enhance its optoelectrical properties and expand the potential applications. In this work, the mechanisms, for how dopants affect the overall structural, optical, electrical, and chemical properties and stability of lead halide perovskite materials, are investigated. This is done by specifically considering various bismuth (Bi)doping concentrations in MAPbBr3 single crystals grown using the inverse temperature crystallization method. The resultant doped single crystals exhibit a saturation point when Bi concentration exceeds 0.063% which is considered an optimum doping point. The highest thermal stability is also achieved at this doping concentration among the doped single crystals. This study clearly identifies how Bi doping affects the properties of MAPbBr3 and extends to consider stability, which has not been fully considered for MA-based perovskites previously. This will provide a clear understanding of evaluating doped perovskite materials for enhanced material properties, device performance, and stability.

Bi doping induces the quantum dots to improve the supercapacitor performance of cobalt carbonate hydroxide hydrate

Cobalt carbonate hydroxide has been widely used in supercapacitor electrodes because of its excellent theoretical electrochemical properties and easy synthesis. However, in actual synthesis, its excellent electrochemical properties are often weakened due to its oxide-like properties, which restricts its further development. Herein, the Bi heteroatoms are introduced into the Co(CO3)0.5(OH)·0.11H2O, which not only modifies the microstructure, but also induces the formation of quantum dots, thus improving the performance of supercapacitors. By regulating the doping amount of Bi, the optimized Co/Bi-3:1 exhibits a specific capacitance of 680 F g−1 at 1 A g−1, which is 5.74 times than the pristine Co(CO3)0.5(OH)·0.11H2O. Furthermore, the assembled Co/Bi-3:1//activated carbon soft-pack asymmetric supercapacitor has a relatively superior power density (10547.58 W kg−1, relative to 14.06 Wh kg−1 energy density) and energy density (17.83 Wh kg−1, relative to 2146.76 W kg−1 power density). The present study demonstrates that Bi doping not only facilitates the formation of quantum dots and enhances electron conduction ability, but also regulates the microscopic morphology, thereby enhancing the electrochemical energy storage capacity of cobalt carbonate hydroxide hydrate electrode materials.

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.

Dielectric Relaxation, Electrical Conductivity, Dielectric Permittivity, and Correlated Barrier Hopping Conduction Mechanism Analysis in Ag Doped Bi2S3 at Low Temperatures

AbstractPure and 6% Ag doped bismuth sulfide (Bi2S3) were synthesized via solid‐state reaction method at 500 °C. The X‐ray diffraction method confirmed the orthorhombic phase with average crystallite size ∼25 nm and average lattice strain ∼0.5% and ∼0.6% for pure and 6% Ag doped Bi2S3. The scanning electron microscope (SEM) images confirmed nanobelt morphology. A direct bandgap of ∼3.3 and ∼3.4 eV for pure and doped Bi2S3 was estimated using UV–vis spectroscopy, respectively. AC measurements were performed from 200 Hz to 2 MHz at temperature 223–298 K. Investigation of Nyquist plots of 6% Ag doped Bi2S3 nanobelts suggested space‐charge‐dependent behavior and indicated an negative temperature coefficient of resistance (NTCR). AC conductivity adhered to Jonscher's power law in which the decreasing trend of s‐parameter with increasing temperature indicates correlated barrier hopping conduction mechanism. From this model, hopping distance (∼10−9–10−11 m) and density of states (∼1022–1023 eV−1 cm−3) were estimated. The dielectric permittivity exhibited dispersion at low frequencies due to the combined effect of electronic, ionic, and interfacial polarizations. Presence of two semicircular arcs in the complex modulus analysis suggested the presence of both grain and grain‐boundary effects.

Bandgap Engineering via Doping Strategies for Narrowing the Bandgap below 1.2 eV in Sn/Pb Binary Perovskites: Unveiling the Role of Bi3+ Incorporation on Different A-Site Compositions.

The integration of perovskite materials in solar cells has garnered significant attention due to their exceptional photovoltaic properties. However, achieving a bandgap energy below 1.2 eV remains challenging, particularly for applications requiring infrared absorption, such as sub-cells in tandem solar cells and single-junction perovskite solar cells. In this study, we employed a doping strategy to engineer the bandgap and observed that the doping effects varied depending on the A-site cation. Specifically, we investigated the impact of bismuth (Bi3+) incorporation into perovskites with different A-site cations, such as cesium (Cs) and methylammonium (MA). Remarkably, Bi3+ doping in MA-based tin-lead perovskites enabled the fabrication of ultra-narrow bandgap films (~1 eV). Comprehensive characterization, including structural, optical, and electronic analyses, was conducted to elucidate the effects of Bi doping. Notably, 8% Bi-doped Sn-Pb perovskites demonstrated infrared absorption extending up to 1360 nm, an unprecedented range for ABX3-type single halide perovskites. This work provides valuable insights into further narrowing the bandgap of halide perovskite materials, which is essential for their effective use in multi-junction tandem solar cell architectures.

Bismuth-doping Induced Enhanced Humidity Sensing Properties of Spinel NiFe2O4 Nanoparticles

Bi-doped NiFe2O4 nanoparticles were tested for humidity detection at various RH levels at room temperature. The findings indicated that sensors with higher Bi concentrations, particularly the ones with 20 % Bi doping, showed significantly enhanced sensing response—up to 97 %, a sixfold increase compared to undoped sensors. This significant improvement suggests that Bi contributes to synergistic effects that boost sensor performance. Density Functional Theory (DFT) calculations support this by showing that Bi introduces acceptor electronic states, heightening electrical responsiveness to moisture. These Bi-doped sensors exhibit quick response times, high accuracy, negligible hysteresis, and impressive stability, making them promising candidates for reliable humidity detection.

Modulating the Bader Charge Transfer in Single p‐Block Atoms Doped Pd Metallene for Enhanced Oxygen Reduction Electrocatalysis

AbstractMetallene is considered as an emerging family of electrocatalysts due to its atomically layered structure and unique surface stress. Here we propose a strategy to modulate the Bader charge transfer (BCT) between Pd surface and oxygenated intermediates via p‐d electronic interaction by introducing single‐atom p‐block metal (M=In, Sn, Pb, Bi) into Pd metallene nanosheets towards efficient oxygen reduction reaction (ORR). X‐ray absorption and photoelectron spectroscopy suggests that doping p‐block metals could facilitate electron transfer to Pd sites and thus downshift the d‐band center of Pd and weaken the adsorption energy of O intermediates. Among them, the developed Bi−Pd metallene shows extraordinarily high ORR mass activity of 11.34 A mgPd−1 and 0.86 A mgPd−1 at 0.9 V and 0.95 V in alkaline solution, respectively, representing the best Pd‐based ORR electrocatalysts ever reported. In the cathode of a Zinc‐air battery, Bi−Pd metallene could achieve an open‐circuit voltage of 1.546 V and keep stable for 760 h at 10 mA cm−2. Theoretical calculations suggest that the BCT between Pd surface and *OO intermediates greatly affects the bond length between them (dPd‐*OO) and Bi doping could appropriately reduce the amount of BCT and stretch the dPd‐*OO, thus enhancing the ORR activity.

Effects of Bi Doping on Zn-Rich Phase Evolution and Physical and Chemical Properties of Sn-6.5Zn Lead-Free Solder Alloy

Effects of Bi Doping on Zn-Rich Phase Evolution and Physical and Chemical Properties of Sn-6.5Zn Lead-Free Solder Alloy

Ultrahigh Stability and Operation Performance in Bi-doped GeTe/Sb2Te3 Superlattices Achieved by Tailoring Bonding and Structural Properties.

Changes in bond types and the reversible switching process between metavalent and covalent bonds are related to the operating mechanism of the phase-change (PC) behavior. Thus, controlling the bonding characteristics is the key to improving the PC memory performance. In this study, we have controlled the bonding characteristics of GeTe/Sb2Te3 superlattices (SLs) via bismuth (Bi) doping. The incorporation of Bi into the GeTe sublayers tailors the metavalent bond. We observed significant improvement in device reliability, set speed, and power consumption induced upon increasing Bi incorporation. The introduction of Bi was found to suppress the change in density between the SET and RESET states, resulting in a significant increase in device reliability. The reduction in Peierls distortion, leading to a more octahedral-like atomic arrangement, intensifies electron-phonon coupling with increased bond polarizability, which are responsible for the fast set speed and low power consumption. This study demonstrates how the structural and thermodynamic changes in phase change materials alter phase change characteristics due to systematic changes of bonding and provides an important methodology for the development of PC devices.

Synergistic effect of Bi and Fe for suppressing hydrogen evolution reaction (HER) and enhancing electrochemical nitrogen reduction reaction (eNRR) performance

The electrochemical nitrogen reduction reaction (eNRR) displays significant potential for the synthesis of ammonia. However, eNRR electrocatalysts with high catalytic activity and selectivity still need to be developed. In this study, a Bi-doped La0.9Bi0.1FeO3-δ (LBiF) perovskite was fabricated as a potential cathode catalyst and incorporated into a protonic ceramic electrolysis cell (PCEC) for eNRR. Electrochemical tests demonstrated that the LBiF cathode reveals higher eNRR catalytic activity and enhanced hydrogen evolution reaction (HER) inhibition compared to undoped LaFeO3 (LF). Characterization of the LBiF cathode following 90 h of NH3 synthesis revealed surface reconstruction of the catalyst during eNRR. Particularly, Bi3+ is partially reduced to Bi2+ and metallic Bi, resulting in A-site defects and an increased concentration of oxygen vacancies (OVs) and Fe4+ in accordance with the charge neutrality principle. Both the OVs and Fe4+ can accept electron pairs provided by N2 due to their unsaturated electronic structures. Furthermore, Bi doping inhibits the HER because Bi preferentially binds to N instead of H. Bi doping creates new Bi3+/Bi2+/Bi0 redox electron pairs, establishing an electron transfer path that improves perovskite conductivity and eNRR electrocatalytic activity. This study sets a foundation for designing eNRR catalysts aimed at suppressing the HER.

Impact of doping on MgB2 superconductors: A comprehensive review

This review introduces fresh insights into the ongoing discussion on doping in the MgB2 superconductor compound, enriching the comparative analysis with previous reviews. Its primary objective is to succinctly summarize and enhance comprehension regarding the influence of doping on the superconducting properties of MgB2. It delves into various aspects, including the impact on the superconducting transition temperature (Tc) and the critical current density (Jc) of the doped samples, while also shedding light on the diverse synthesis methodologies employed by different research laboratories. Throughout the review, the doping agents under scrutiny encompass a wide array, ranging from Li and Be to Bi and Pb. The properties are compared with those undoped samples crafted by the authors of each publication. This review catalogs a range of cited doping agents, including H, Li, Be, C, C15H12O2, diamond, graphene oxide, NaCl, Na2CO3, Mg, Al, Si, K2CO3, CaH2, CaCO3, Sc, Ti, Ni, Cu, Zn, MgGa, GeO2, Se, Rb2CO3, Rh, Pd, Ag, In, Sn, Sb2O3, Te, Cs2CO3, LaB6, La2O3, CeO2, Pr6O11, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, Os, Ir, Pt, Hg, Pb, and Bi. Notably, doping with Be, Na2CO3, C, Al, Rb2CO3, Cs2CO3, Hg and Pb impacts mesh parameters through either Mg or B substitution. Conversely doping with Li, CaH2, Cu, Ag, La2O3, CeO2, Pr6O11, Nd2O3, Gd2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Lu2O3, GeO2, Rh, In, Sb2O3, and Pt exhibits minimal impact on Tc. Moreover, Jc can be substantially enhanced by adding C, Zn, Ag, or Sb2O3. Remarkably, the incorporation of Pd or Pt has shown a substantial increase in Jc with a remarkable improvement of +328 % and +614 % respectively observed at 2 T and 20 K. Doping with rare earth elements such as La2O3, Sm2O3, Eu2O3, Gd2O3, Tb2O3, and Ho2O3 resulted in extraordinary improvement in the value of the critical current density at 20 K under specific conditions, within a range of 0–4 T.

Photoelectrochemical Oxidation of Glycerol over g-C3N4 Nanosheets Coupled with Metal-Assisted Hybrid Carbon Quantum Dots

Carbon quantum dots (CDs) are the most promising candidates of the carbon family with a size of less than 10nm. They owned superior properties such as high solubility in aqueous medium, low toxicity, biocompatibility, stable photoluminescence, spectral convertor, and act as electron reservoirs. These properties make CDs suitable for photo-electrochemical catalytic applications. Low quantum yield and activity in the visible light spectrum of CDs may restrict their applicability. To address this issue, doping and surface passivation of CDs is the only approach to improve their physicochemical characteristics, visible light absorption, and quantum yield by altering their size and structure. Metals are electron-efficient entities and act as electron donors. As a result, when metal ions are doped into CDs, the charge density and charge transition between the core of the CDs and the metal ions increases. This results in a greater improvement in the physicochemical properties of CDs as compared to non-metal doping[1]. Metal-assisted CDs i.e. hybrid CDs tend to modulate energy band positions, change the electronic structure, increase quantum yield, and generate new emissive traps in CDs. The photoluminescence property of CDs can be enhanced due to the surface plasmonic resonance (SPR) effects of metal nanoparticles (NPs). Hybrid CDs also show better catalytic performance as compared to the pristine CDs. It helps to enhance the active sites on the CDs surface to facilitate catalytic performance.By keeping these properties, the hybrid CDs were effectively utilized in the field of dye decolorization, degradation of water pollutants, storage materials, and as a sensor[2][3]. The photo-assisted electrochemical glycerol valorization is one of the prominent methods for producing value-added chemicals such as glycolic acid. However, it is a challenge to achieve high yield and selectivity of products. This research investigated the fabrication of heterojunction of g-C3N4 (CN) with CDs and Bi-assisted CDs (BiCD) as a sustainable photoactive material. The heterojunction was obtained by incorporating CDs and BiCD (5wt.% each) onto CN nanosheets by in-situ thermal polymerization treatment and named CDCN and BiCDCN. The prepared composite was analyzed by structural (XRD), functional (XPS) microscopic (FESEM, FETEM) spectroscopic (UV-Vis, PL, TRPL, EDS), and photoelectrochemical characterization techniques.The band gap of CN was obtained as 2.78 eV which was reduced to 2.69 eV for CDCN and 2.62eV for BiCDCN, increasing the absorbance in the visible light zone. The existence of CDs and BiCDs was confirmed by, FETEM investigation (Fig.1a). The XPS analysis of the composite revealed the presence of Bi 4f chemical state of bismuth metal. The calculated TRPL lifetime was 0.28ns for BiCDCN and 2.51 ns for CDCN which was lower than that of CN (9.31 ns) suggesting the rapid electron transfer ability of BiCDCN. In the presence of light and glycerol, the composite BiCDCN had the maximum photocurrent density of 12 mA/cm2, followed by CDCN (1.6 mA/cm2) and CN (1.3 mA/cm2) at 1.2 V. The photoelectrochemical oxidation of glycerol was performed at 0.8V for 3h. The detected products were glycolic acid, glyceric, glyoxylic acid, and oxalic acid. The addition of CD to CN increased the glycerol conversion and yield of glycolic acid & glyoxylic acid significantly. The composite exhibited 43% selectivity towards glycolic acid and 34% for glyoxylic acid. The glycerol conversion and yield of these two products were further enhanced by Bi doping. BiCDCN had a total glycerol conversion of 21%, followed by CDCN at 5.7% and CN at 3.8%. The BiCDCN had the highest yield of glycolic acid at 8.9 % and that for CDCN was 2.4 % and 1.2 % for CN (Fig.1b). The glyoxylic acid yield was 7.2%, 2.2%, and 0.8% for BiCDCN, CDCN, and CN, respectively. Figure 1

Bi1‐CuCo2O4 Hollow Carbon Nanofibers Boosts NH3 Production from Electrocatalytic Nitrate Reduction

AbstractAmmonia, as a high‐energy‐density carrier for hydrogen storage, is in great demand worldwide. Electrocatalytic nitrate reduction reaction (NO3RR) provides a green NH3 production process. However, the complex reaction pathways for NO3RR to NH3 and the difficulty in controlling intermediate products limit the reduction process. Herein, by incorporating atomic‐level bismuth (Bi) into CuCo2O4 hollow carbon nanofibers, the catalytic activity of the electrocatalyst for NO3RR is enhanced. The maximum Faradaic efficiency of Bi1‐CuCo2O4 is 95.53%, with an NH3 yield of 448.74 µmol h−1 cm−2 at −0.8 V versus RHE. Density Functional Theory calculations show that the presence of Bi lowers the reaction barrier for the hydrogenation step from *NO2 to *NO2H, while promoting mass transfer on the release of *NH3 and the reactivation of surface‐active sites. Differential charge density calculations also show that after Bi doping, the charge supplied by the catalyst to NO3− increases from 0.62 to 0.72 e‐, thus reasoned for enhanced NO3RR activity. The established nitrate‐Zn battery shows an energy density of 2.81 mW cm−2, thus implying the potential application.

Enhanced highly bismuth‐doped multicomponent phosphate glass fibers for broadband amplifiers

AbstractBismuth (Bi)‐doped glass fibers are being developed into next‐generation broadband amplifiers and tunable lasers. Yet, the well‐developed Bi‐doped fiber devices only realize silica‐based optical fibers prepared by the modified chemical vapor deposition method, which faces challenges such as low doping concentration, high cost, intricate device structure, and high preparation difficulty. Here, a novel highly Bi‐doped multicomponent phosphate glass was developed. The high ion solubility of this phosphate glass facilitates achieving a Bi doping concentration of 8 mol%. The introduction of aluminum nitride (a new reducing agent) can create a local reducing environment, further increasing the concentration of low‐valence near‐infrared (NIR) active Bi ions. Furthermore, the resulting enhanced highly Bi‐doped multicomponent phosphate glass with efficient 900–1600 nm NIR emission can be drawn into corresponding optical fibers by a rod‐in‐tube method. Broadband NIR amplified spontaneous emission with a 3 dB bandwidth of 275 nm was achieved in this new fiber. As far as we know, this is the first successful preparation of Bi‐doped multicomponent phosphate glass fiber. Our results indicate that this fiber will be a powerful alternative to Bi‐doped silica‐based fibers for the preparation of related Bi‐doped fiber devices.

Unveiling the structural and optoelectronic properties of (P, Bi, Sb)-doped GaAs by first- principles calculations

In this work, we investigate the influence of M substitutions (M = P, Bi, and Sb) on the structural, electronic, and optical properties of gallium arsenide, GaM x As1-x for x=0,0.25,0.50,0.75,1.0 using density functional theory (DFT). We have observed that the cubic symmetry of the semiconductors in conserved, and lattice constants show a linear behavior with dopant concentration, according to Vegard’s law. Specifically, the lattice constants increased for Bi and Sb dopants, whilst decreased for P dopants. Furthermore, the bulk modulus decreased with an increase in M-concentration for all M-doped systems. The energy analysis showed that the P-doped system was the most stable system. In terms of the electronic band structure, all M-doped compounds exhibited a direct electronic band gap. The P-doped system showed a wide band gap, while the Sb-doped systems displayed a narrow band gap, both compared to pristine GaAs. The Bi-doped system showed metallic-like behavior. To gain insights into the linear optical properties of the GaM x As1-x compounds, we calculated the real and imaginary parts of the dielectric function, as well as other optical parameters such as the absorption coefficient, refractive index, extinction coefficient, and reflectivity. The results showed that P doping leads to a blue-shift in the optical absorption coefficient, while Bi and Sb doping lead to a red-shift. These findings provide valuable theoretical insights for the potential application of GaM x As1-x semiconductors in photovoltaics and optoelectronic devices.

Optimization of energy storage and electrocaloric performance in Pb(Zr,Ti)O3 via A-Site La and Bi Co-doping

Lead-based ferroelectrics are one of the most fascinating candidates in the field of state-of-the-art electronic technology. Their intriguing properties are further enriched via the realization of morphotropic phase boundaries. Moreover, the A-site chemical substitution provides insight into the emergence of various exotic phases. Here, we employ co-doping of La3+ and Bi3+ at the A-site of Pb(Zr,Ti)O3 (PZT) ferroelectric to broaden the practical perspective of relaxor systems. Here, we emphasize that the A-site co-doping approach introduces technologically appealing amendments in the well-established temperature composition phase diagram of the PZT system. La3+ and Bi3+ doping favors the evolution of a novel response to thermal and field fluctuations. The maximum values of −ΔS are found to be ∼0.157, 0.118 and 0.176 J (kg·K)−1 for x=0.01, 0.02 and 0.03 , respectively. We employ the electrocaloric characteristics and Arrott plot as probing tools. The observation of a negative electrocaloric effect and the systematic reversal of Arrott lines, followed by a poling effect on the dielectric constant, reveals the emergence of ergodic phase as a novel phase. This further reveals that the Bi doping approach leads to the emergence of exotic characteristics in the chemically modified PZT system. The maximum observed recoverable energy for the composition for x = 0.01 is 0.0479 J cm−3 at a temperature of 388 K.

Reliability Risk Mitigation in Advanced Packages by Aging-Induced Precipitation of Bi in Water-Quenched Sn-Ag-Cu-Bi Solder.

Bi-doped Sn-Ag-Cu (SAC) microelectronic solder is gaining attention for its utility as a material for solder joints that connect substrates to printed circuit boards (PCB) in future advanced packages, as Bi-doped SAC is reported to have a lower melting temperature, higher strength, higher wettability on conducting pads, and lower intermetallic compound (IMC) formation at the solder-pad interface. As solder joints are subjected to aging during their service life, an investigation of aging-induced changes in the microstructure and mechanical properties of the solder alloy is needed before its wider acceptance in advanced packages. This study focuses on the effects of 1 to 3 wt.% Bi doping in an Sn-3.0Ag-0.5Cu (SAC305) solder alloy on aging-induced changes in hardness and creep resistance for samples prepared by high cooling rates (>5 °C/s). The specimens were aged at ambient and elevated temperatures for up to 90 days and subjected to quasistatic nanoindentation to determine hardness and nanoscale dynamic nanoindentation to determine creep behavior. The microstructural evolution was investigated with a scanning electron microscope in tandem with energy-dispersive spectroscopy to correlate with aging-induced property changes. The hardness and creep strength of the samples were found to increase as the Bi content increased. Moreover, the hardness and creep strength of the 0-1 wt.% Bi-doped SAC305 was significantly reduced with aging, while that of the 2-3 wt.% Bi-doped SAC305 increased with aging. The changes in these properties with aging were correlated to the interplay of multiple hardening and softening mechanisms. In particular, for 2-3 wt.% Bi, the enhanced performance was attributed to the potential formation of additional Ag3Sn IMCs with aging due to non-equilibrium solidification and the more uniform distribution of Bi precipitates. The observations that 2-3 wt.% Bi enhances the hardness and creep strength of the SAC305 alloy with isothermal aging to mitigate reliability risks is relevant for solder samples prepared using high cooling rates.

Modulating the Bader Charge Transfer in Single p-Block Atoms Doped Pd Metallene for Enhanced Oxygen Reduction Electrocatalysis.

Metallene is considered as an emerging family of electrocatalysts due to its atomically layered structure and unique surface stress. Here we propose a strategy to modulate the Bader charge transfer (BCT) between Pd surface and oxygenated intermediates via p-d electronic interaction by introducing single-atom p-block metal (M=In, Sn, Pb, Bi) into Pd metallene nanosheets towards efficient oxygen reduction reaction (ORR). X-ray absorption and photoelectron spectroscopy suggests that doping p-block metals could facilitate electron transfer to Pd sites and thus downshift the d-band center of Pd and weaken the adsorption energy of O intermediates. Among them, the developed Bi-Pd metallene shows extraordinarily high ORR mass activity of 11.34 A mgPd -1 and 0.86 A mgPd -1 at 0.9 V and 0.95 V in alkaline solution, respectively, representing the best Pd-based ORR electrocatalysts ever reported. In the cathode of a Zinc-air battery, Bi-Pd metallene could achieve an open-circuit voltage of 1.546 V and keep stable for 760 h at 10 mA cm-2. Theoretical calculations suggest that the BCT between Pd surface and *OO intermediates greatly affects the bond length between them (dPd-*OO) and Bi doping could appropriately reduce the amount of BCT and stretch the dPd-*OO, thus enhancing the ORR activity.