Bi Powder Research Articles

Photocatalytic dye degradation, H2 evolution, electrical and mechanical performances of mechano-synthesized multifunctional Bi2Te3 nanoparticles: Effect of milling time and thermal treatment

Bi2Te3 nanoparticles are synthesized by mechanical alloying the Bi and Te powders under the Ar and pressed powdered samples are sintered at 573 K. Rietveld refined XRD patterns, FESEM images and EDX spectra reveal the microstructure, morphology and phase purity of the samples. Bandgaps are obtained from the FTIR spectra and a blue shift with size reduction indicates the size confinement effect. The non Debye type ac conductivity and dielectric constant variations with milling time and sintering are measured. The improved photocatalytic degradation efficiency of the sintered sample (83.59 %) using Rhodamine B dye under visible light elucidates reduced porosity effect. The photocatalytic hydrogen evolution efficiencies of these nanoparticles are measured and a probable mechanism is depicted. The highest H2 generation efficiency (1462.5 μmol g−1h−1) is observed with the sintered sample. Microhardness measurement reveals normal indentation size effect. Empirical correlations among electrical conductivity, microhardness and photodegradation are established for the first time.

Catalysis of Silver and Bismuth in Various Epoxy Resins.

Epoxy resins find extensive utility across diverse applications owing to their exceptional adhesion capabilities and robust mechanical and thermal characteristics. However, the demanding reaction conditions, including extended reaction times and elevated reaction temperature requirements, pose significant challenges when using epoxy resins, particularly in advanced applications seeking superior material properties. To surmount these limitations, the conventional approach involves incorporating organic catalysts. Within the ambit of this investigation, we explored the catalytic potential of metallic powders, specifically bismuth (Bi) and silver (Ag), in epoxy resins laden with various curing agents, such as diacids, anhydrides, and amines. Metallic powders exhibited efficacious catalytic activity in epoxy-diacid and epoxy-anhydride systems. In contrast, their influence on epoxy-amine systems was rendered negligible, attributed to the absence of requisite carboxylate functional groups. Additionally, the catalytic performance of Bi and Ag are different, with Bi displaying superior efficiency owing to the presence of inherent metal oxide layers on its powder surfaces. Remarkably, the thermal and mechanical properties of uncatalyzed, fully cured epoxy resins closely paralleled those of their catalyzed counterparts. These findings accentuate the potential of Bi and Ag metal catalysts, particularly in epoxy-diacid and epoxy-anhydride systems, spanning a spectrum of epoxy-based applications. In summary, this investigation elucidates the catalytic capabilities of Bi and Ag metal powders, underscoring their ability to enhance the curing rate of epoxy resin systems involving diacids and anhydrides but not amines. This research points toward a promising trajectory for multifarious epoxy-related applications.

Macro-encapsulation of metallic phase change materials with sacrificial density less than 3.5 % for medium-temperature heat storage

To solve the problems of volume thermal expansion and high chemical activity of metallic phase change materials (PCMs), this paper successfully prepared millimeter/centimeter-size durable Bi@Void@Kaolin macrocapsules. Fortunately, carbon powder clusters from the thermal decomposition of adhesive CMC gathered on the core PCMs, cleverly adding a reducing atmosphere into the capsules. In particular, the buffer voids of macrocapsules were created from the pores and gaps between the accumulated Bi powders, and the method of improving the bulk density of powder cores as core precursors by the cold isostatic pressing (CIP) technology solves the problem of excessive cavity volume. Thermal analysis indicates that after CIP treatment, the heat storage density of the Bi@Kaolin macrocapsule with the unpressurized powder core volume accounting for 50% can be increased by 18.4%–275.0 J/cm3, which is about 2.5 times the heat storage density of the common medium-temperature heat storage materials - concrete and NaCl, under the working temperature range of 240–300 °C. Solid-liquid PCMs need to sacrifice their density in exchange for the necessary cavity volume, therefore the “actual volumetric heat storage density” of PCMs should be specified. The results show that the proportion of sacrificial density of Bi PCM (i.e. the cavity rate of Bi-based macrocapsule) can reach the optimal value of 3.5%, its actual volumetric heat storage density can reach 558.9 J/cm3 at 240–300 °C. Surprisingly, all the Bi@Kaolin macrocapsules showed excellent cycling durability and thermal stability during 500 cycles under air atmosphere and subsequent 24 h overload-temperature oxidation tests.

Ultra-fast synthesis of Bi2Te3−xSex based compounds with micro-nano composite structure at room temperature by reactive flash sintering

The synthesis of Bi2Te3−xSex (x = 0 and 0.3) compounds in a few seconds at room temperature was realized by reactive flash sintering method using Bi, Te and Se raw powders. The phase transition and microstructure evolution during flash sintering were systematically studied relating to the duration time, power density and sample temperature. The synthesized Bi2Te3−xSex compounds have micro-nano composite structure, which are composed of 5–10 μm lamellar crystal and 10–20 nm nanograin. It is suggested that the instantaneously generated local Joule heat throughout the sample and the resulted ultra-high self-heating rate approaching tens of thousands K/min are responsible for the synthesis of highly crystalline Bi2Te3−xSex. The synthesis mechanism is proposed, including Joule heating, melting, chemical reaction, nucleation and grain growth. This highly efficient and economic synthesis method of Bi2Te3−xSex compounds with micro-nano composite structure has great potential for application in the field of thermoelectric industry.

Microstructure correlated optical, electrical and mechanical characterizations of (Bi1-xSbx)2Te3: Effect of compositional variations on different properties

Nanocrystalline rhombohedral (Bi1-xSbx)2Te3 (with x = 0, 0.25, 0.5, 0.75, 1) powders are synthesized by a facile one-pot mechanical milling technique using elemental Bi, Sb, and Te powders, taken in different proportions within 3 h of milling. The Rietveld refined X-ray diffraction (XRD) patterns of the fabricated samples reveal the compositional variations of different microstructural parameters like crystallite size, lattice strain, and lattice parameters. The included impurity percentages of Bi and Sb explain the variation of lattice parameter a, whereas, the antisite defects are well interpreted with the change in lattice parameter c. The r.m.s. lattice strain is consistent with the formulation of different antisite defects acting as either n-type or p-type doping within the materials (Bi1-xSbx)2Te3. The microstructure is also revealed from the field-emission scanning electron microscope (FESEM) image and energy dispersive X-ray (EDX) spectrum and compared with the results obtained from the XRD pattern analysis. The narrow bandgaps of the materials are determined from the Fourier transform infrared (FTIR) spectra, and the correlation with the microstructure establishes their changes with the compositional x value. Here, both the blue and red shifts in bandgap with particle size variations are observed and explained. The positions of the conduction and valence bands are determined with composition variations (x). The non-Debye type, thermally activated conduction process of the semiconducting materials is confirmed from the ac electrical study of the samples at room and high temperatures. The variation of electrical conductivity with different alloying concentrations and temperatures is explained in terms of their particle size and density of antisite defects. The conduction mechanism is found to be a small polaron hopping model. The Vickers microhardnesses of the samples are measured and explained by correlating with the microstructural parameters. The Meyer's law establishes the normal indentation size effect (ISE). The microhardness of the materials partially supports the conductivity results.

Influence of glycine addition on formation and magnetic properties of MnBi prepared by vacuum sintering technique

An alternative way to increase a low-temperature phase MnBi (LTP-MnBi) content synthesized by low-temperature vacuum sintering is by using Mn powder with small particle sizes. To reduce the particle size by ball milling, glycine was added to prevent particle agglomeration and possible oxide formation. The ball-milled Mn and Bi powders were fixed at an atomic ratio of 1:1. The ball-milling time in glycine was between 1 and 3 hrs. The average particle size reduces from 400 µm (original) to 35-40 µm and 15-20 µm after grinding for 1 and 3 hr, respectively. Sintering of the mixtures was carried out at 275 °C for 12 hours at a vacuum pressure of less than 5×10−8 mbar. The LTP-MnBi samples sintered from 1 hr (MnG1Bi) and 3 hr (MnG3Bi) glycine-added Mn grinding times were investigated by XRD, SEM, XPS, and VSM. The coercivity values (H c) are 3.95 ± 0.04 and 2.35 ± 0.03 kOe for MnG1Bi and MnG3Bi, respectively. The saturation magnetization (M s) of MnG1Bi and MnG3Bi is relatively low (~0.18 emu/g) compared to the samples prepared by conventional ball-milling, i.e., without adding glycine in grinding. The XRD results show a few percentages of MnBi content in all samples, suggesting that glycine addition could prevent MnBi formation. The coverage of hydrocarbon (i.e., NH2-CH2-COOH) groups on Mn particles could prevent the diffusion mechanism during liquid-phase sintering. Moreover, it was found that the oxygen and carbon content in the MnGxBi were much higher than the conventional ball-milled MnBi.

Novel polypropylene-TiO2:Bi spherical floater for the efficient photocatalytic degradation of the recalcitrant 2,4,6-TCP herbicide

In this work, spherical photocatalytic floaters were fabricated by depositing TiO2:Bi (TBi) particles on polypropylene (PP) spheres (recycled from beer cans). These particles were deposited on the sphere (TBi-sphere) by the spray coating technique and evaluated their performance for the photocatalytic degradation of 2,4,6-trichlorophenol (2,4,6-TCP) herbicide. SEM images demonstrated that the BTi powders consisted in conglomerated grains with sizes of 20–80 nm and the analysis by X-ray diffraction confirmed the presence of rutile and anatase phases in the BTi. The photocatalytic experiments showed that the TBi and TBi-sphere produced maximum degradation of 90 and 97% for 2,4,6-TCP, respectively, after 4 h under UV–Vis light. The photocatalytic powders/composites were reused 3 times and the loss of degradation efficiency was 3 and 16% for the TBi powder and TBi-sphere, respectively. This means that the TBi-sphere is more stable for the continuous degradation of the 2,4,6-TCP contaminant. The TiO2:Bi powder was compared with the commercial TiO2 (P25) and found that the TiO2:Bi powder had higher light absorption (≈42%) and higher surface area (≈105%) than the P25. Therefore, the degradation percentage for the 2,4,6-TCP was 52% higher in the sample doped with Bi. Also, scavenger experiments were carried out and found that the main oxidizing agents produced for the degradation of 2,4,6-TCP were •OH− radicals and •O2− anions. Other species such as h+ were also produced at lower amount. Hence, our results demonstrated that spherical/floatable photocatalytic composites are a viable option to remove herbicide residuals from the water, which is of interest in water-treatment-plants.

Luminescence and defects creation processes in Bi3+-doped gallium garnets

Microcrystalline powders of Y3Ga5O12:Bi and Gd3Ga5O12:Bi are investigated by the X-ray diffraction, scanning electron microscopy, time-resolved photoluminescence, and thermally stimulated luminescence methods in a wide temperature range (4.2–500 K). The results are compared with those obtained recently for the Lu3Ga5O12:Bi powder. The presence of the ultraviolet (UV) emission of a Bi3+ ion and the visible (VIS) emission of an exciton localized around the Bi3+ ion is confirmed for all the investigated gallium garnets. The processes of photostimulated creation of electron and hole centers taking place under irradiation in the 4–6 eV energy range are investigated. The origin of the hole centers responsible for the UV and VIS electron recombination luminescence is clarified. Electron transitions between the energy levels of Bi3+ ions and the Bi3+ → Ga3+oct, Bi3+ → Ga3+tetr, and Bi3+ → Y3+ or Bi3+ → Gd3+ electron transfer transitions are found to appear in the photo- and thermoluminescence excitation spectra. The Bi3+ energy level positions in the band gap are determined. Their influence on the luminescence and photostimulated creation of electron and hole centers is discussed.

Sonochemical Synthesis of Large Two‐Dimensional Bi2O2CO3 Nanosheets for Hydrogen Evolution in Photocatalytic Water Splitting

AbstractLaterally large (≈3 µm), atomically thin 2D Bi2O2CO3 nanosheets (2D bismuth oxycarbonate, 2D bismutite) are fabricated via sonochemically assisted, template‐free synthesis. Keys to the synthesis of the freestanding, laterally large 2D Bi2O2CO3 nanosheets from bulk Bi powder are choice of suspension medium, controlled reaction temperatures, and several hours processing time. Lateral sizes of 2D Bi2O2CO3 can be controlled between µm‐sized nanosheets and tens of nm sized nanoflakes solely based on the choice of suspension medium. The here introduced 2D Bi2O2CO3 nano‐sheets/‐flakes are then hybridized by a simple mix‐and‐match approach with TiO2 nanoparticles for testing in suspension‐type photocatalytic hydrogen production via water splitting. This introduces the 2D Bi2O2CO3 as a prospective noble‐metal‐free catalyst component with TiO2 for photocatalytic hydrogen evolution, beyond Bi2O2CO3's current use as photocatalyst for organic pollutant degradation. These results enrich the fabrication toolbox of emerging 2D pnictogen oxycarbonates toward large 2D nanosheets and demonstrate the potential of 2D Bi2O2CO3 as a catalyst component for hydrogen evolution in photocatalytic water splitting.

Combustion-driven synthesis route for bimetallic Ag–Bi nanoparticle-anchored carbon nanotube electrodes for high-performance supercapacitors

Bimetallic nanostructures within carbon-based materials can overcome the fundamental limits of energy materials, which cannot be obtained using a single material. However, their synthesis involves time-consuming and complex processes that cause phase/interface segregation and non-uniformly distributed metal elements. Herein, we report a facile combustion-driven synthesis for bimetallic Ag–Bi nanoparticle (NP)-anchored carbon nanotube (CNT) electrodes. One-step combustion wave passing through freestanding films comprising Ag2O and Bi powders, nitrocellulose layers within CNTs enables high-density thermochemical reactions in seconds. The rapid heating-cooling rates induce the formation of liquefied Ag–Bi and trapping of metastable Ag–Bi phases at the carbon surfaces, thereby synthesizing homogeneously mixed bimetallic Ag–Bi NPs anchored on the CNTs, along with smaller diameters (∼20 nm) and high distribution density. A supercapacitor electrode employing them exhibits outstanding specific capacitance and retention (1372-1093 Fg-1 at 2-5 mVs−1, and 101.3% of the stabilized capacitance after 10,000 cycles at 100 mVs−1). This was attributed to the large active site surface area from the small diameters and high distribution density of the bimetallic Ag–Bi NPs by low surface energy, and highly stable adhesion to the CNTs. The synthesis strategy can be extended to a scalable fabrication method of various multi-metallic nanostructures for versatile electrochemical electrodes and catalysts.

BiO 2-x Nanosheets with Surface Electron Localizations for Efficient Electrocatalytic CO 2 Reduction to Formate

BiO _2-x Nanosheets with Surface Electron Localizations for Efficient Electrocatalytic CO ₂ Reduction to Formate

Ultra-fast fabrication of Bi2Te3 based thermoelectric materials by flash-sintering at room temperature combining with spark plasma sintering

Highly crystalline Bi2Te3 based compounds with small grain size were successfully synthesized by flash sintering (FS) method in 10 s at room temperature under suitable current density using Bi, Te and Se powders. The instantaneously generated local Joule heat at grain boundary is regarded as the main reason for the rapid completion of chemical reaction and crystallization. By combining FS synthesis method with spark plasma sintering (SPS), Bi2Te3 based bulk materials with high relative density were fabricated in 10 min. Suitably prolonging sintering temperature and holding time in SPS process can decrease carrier concentration and phonon thermal conductivity, while increasing carrier mobility. Hence, the sample prepared at 753 K for 3 min shows 20% higher ZT value than that of the sample prepared at 723 K for 3 min. Compared with common zone melting or powder metallurgy methods taking several hours by complex operation, this method is time-saving and low cost.

Large-scale SHS based 3D printing of high-performance n-type BiTeSe: Comprehensive development from materials to modules

Micro thermoelectric devices have a broad application prospect in confined space refrigeration and power generation of small nodes in the Internet of things. The leg performance, manufacturing efficiency and yield are very important for the industrial production of thermoelectric devices. Here, self-propagating high-temperature synthesis (SHS) and selective laser melting (SLM) technique are combined to directly form a dense and highly growth-oriented n-type BiTeSe material in large scale from raw materials of Bi, Te and Se powders. Ignoring the solid solution of a small amount of Se, the composition and structure analysis of the micro-region via transmission electron microscopy shows that Bi first reacts with Te to form BiTe compound in the molten pool of laser, and then Te reacts with the intermediate BiTe to form Bi2Te3 phase. In the next manufacturing process, a thin bulk material with a size of 60 × 30 × 0.5 mm3 can be printed out within 1 h. Because of the excellent mechanical properties, 4000 valid legs with a size of 0.4 mm × 0.4 mm in plane can be obtained successfully. Finally, a micro thermoelectric device is fabricated via using 3D-printed n-type BiTeSe and commercially hot extrusion p-type BiSbTe legs (28 pairs). For solid refrigeration, the maximum cooling temperature difference is about 44 °C and the maximum cooling power Qmax of the device is about 2.1 W when the input current Imax is about 1.1 A. For power generation, the open-circuit voltage Uoc is 324 mV and the maximum output power Pmax is 4.97 mW when ΔT is 40 K.

Improved thermoelectric performance of nanostructured Bi2Te3 fabricated by solvent-free mechanical alloying

Thermoelectric materials convert waste heat energy efficiently to electricity in an eco-friendly manner. Bi2Te3 is a known thermoelectric material, which can convert waste heat and solar energy into electricity in the 200–400 K temperature range. Bi2Te3 nanocrystals are prepared in powder form by solvent-free mechanical alloying of elemental Bi and Te powder mixtures under an inert Ar atmosphere. The crystallite size and composition of the Bi2Te3 nanocrystals are analyzed using X-ray diffraction, field-emission scanning electron microscope and energy-dispersive X-ray spectroscopy. Thermal and electrical behaviours and the effect of thermal annealing are studied on the 10 h ball-milled sample in a physical properties measurement system in the 30–375 K temperature range. It is observed that the high-temperature thermal annealing induces significant grain growth, reduces lattice strain, along with a reduction of bandgap energy of the mechanically alloyed Bi2Te3 nanostructures. Thermoelectric properties and the figure of merit of the nanostructures have improved significantly upon thermal annealing. Enhanced thermoelectric performance of the annealed nanostructures has been explained considering the change in their thermal conductivity, electrical resistivity, and crystallite size induced by thermal treatment.

Tailoring Cu nano Bi self-lubricating alloy material by shift-speed ball milling flake powder metallurgy

A novel method for preparing lead-free Cu nano Bi (CNB) alloy materials by nano Bi powder and shift-speed ball milling (SSBM) flake powder metallurgy was proposed. To improve the mechanical and tribological properties of the alloy materials, the spherical CuSn10 powder was firstly extruded and sheared into flakes by low-speed ball milling (LSBM) in the SSBM system. Meanwhile, the nano Bi powder was evenly dispersed and coated on the CuSn10 flakes. The mechanical alloying between mixed powders and the cold welding of flake CuSn10 flakes containing nano Bi into layered particles were then realized through short-time high-speed ball milling (HSBM) in the SSBM system. While promoting the uniform dispersion of lubricating phase Bi, the surface area of matrix CuSn10 flake was increased so as to achieve better combination of CuSn10 matrix in the material. Results show that the mechanical properties of the CNB material prepared through nano Bi powder and SSBM flake powder metallurgy improved compared with the Cu-Bi material prepared by HSBM. In addition, the antifriction and wear resistance improved by 30% and 80%, respectively.

Preparation and In‐Situ High‐Throughput Screening of Bi Thixotropic Ink

AbstractPreparing thin‐layer thermoelectric (TE) material libraries through inkjet printing (IJP) combined with selective laser melting (SLM) is a feasible solution to achieve high‐throughput screening (HTS) of high‐performance TE materials. The preparation of stable printable elementary inks with solid particle size in micron‐level is a prerequisite for the realization of the above technical objective. In this work, a series of thixotropic inks containing micron‐sized Bi powder, mixed organic solvent of ethanol/ethylene glycol (EG), and polyurea rheological additive of BYK‐420 are prepared. According to the proposed screening principles for printability and sedimentation stability, the best composition of the Bi thixotropic ink is determined with a solid content of 2–10 vol%, a relative EG content of 2–8 vol%, and a relative additive BYK‐420 content of 2.5 vol%. The effectiveness of the above mentioned HTS method is further proven through the printability Z value and the sedimentation rate of the selected inks. This work provides an effective way for in‐situ high‐throughput screening the printability and sedimentation stability of thixotropic inks, even though the solid density is high and the particle size is in micron‐level. It would lay a solid foundation for further high‐throughput screening of high‐performance TE materials.

Effect of Powder ALD Interface Modification on the Thermoelectric Performance of Bismuth

AbstractIn thermoelectric materials, phase boundaries are crucial for carrier/phonon transport. Manipulation of carrier and phonon scatterings by introducing continuous interface modification has been shown to improve thermoelectric performance. In this paper, a strategy of interface modification based on powder atomic layer deposition (PALD) is introduced to accurately control and modify the phase boundary of pure bismuth. Ultrathin layers of Al2O3, TiO2, and ZnO are deposited on Bi powder by typically 1–20 cycles. All of the oxide layers significantly alter the microstructure and suppressed grain growth. These hierarchical interface modifications aid in the formation of an energy barrier by the oxide layer, resulting in a substantial increase in the Seebeck coefficient that is superior to that of most pure polycrystalline metals. Conversely, taking advantage of the strong electron and phonon scattering, an exceptionally large decrease in thermal conductivity is obtained. A maximum figure of merit, zT, of 0.15 at 393 K and an average zT of 0.14 at 300–453 K were achieved in 5 cycles of Al2O3‐coated Bi. The ALD‐based approach, as a practical interfacial modification technique, can be easily applied to other thermoelectric materials, which can contribute to the development of high‐performance thermoelectric materials of great significance.

Preparation and properties of lead-free copper matrix composites by electroless plating and mechanical alloying

Based on the concept of green design and development, FeS/Cu–Bi lead-free copper matrix composites were prepared by using FeS and Bi powder as lubricating phase to replace the lead in CuPb alloy. Surface modification of FeS powder by electroless plating and mechanical alloying of mixed powder by high-energy ball milling are effective strategies for preparing lead-free copper matrix composites. The effects of surface modification and mechanical alloying on the mechanical and tribological properties of the materials are studied. Results show that electroless nickel plating improves the mechanical locking and metallurgical bonding between mixed powder particles; enhances the interface bonding between FeS particles and copper matrix; and increases the hardness, impact toughness, and crushing strength by 29.7%, 19.4%, and 13%, respectively. The density and hardness of the composite prepared by electroless nickel plating combined with mechanical alloying increases by 11.4% and 40.6%, respectively, average friction coefficient decreases from 0.44 to 0.28, and wear rate decreases by 62%. Electroless plating and mechanical alloying reduce the microploughing and material transfer on the worn surface of the composites, and the abrasive wear and adhesive wear are remarkably improved.

Plasma spray–chemical vapor deposition of nanotextured film with α/β Bi2O3 heterostructure and photocatalytic degradation performance

Bi2O3 film was fabricated on the aluminum foil by highly efficient and low–cost plasma spray–chemical vapor deposition (PS–CVD), using Bi powder as feedstock and plasma jet as heat source. SEM observation shows that the film presents a tree coral–like dendritic morphology which is constructed by Bi2O3 of 60–400 nm particle size. XRD and Fast Fourier transform (FFT) diagram of TEM analyses show that the film is composed of tetragonal β–Bi2O3 and a small part of monoclinic α–Bi2O3. Two band gap widths of 2.54 eV and 2.70 eV were obtained by DRS UV–Vis study, and they are well consistent with β–Bi2O3 and α–Bi2O3, respectively. TEM analysis reveals the heterojunction structure of β–Bi2O3 and α–Bi2O3. The film presents a rapid photodegradation performance of MO with good repetition rate, and the fifth–time degradation efficiency remained 80% of the first–time value. By the comparison of degradation efficiency with using radical scavengers, it is proved that the superoxide radical·O2− plays a major role, while the hydroxyl radical ·OH almost had no effect in the process of MO degradation. The above results open up the possibility of using atmospheric plasma spraying for the preparation of semiconductor nano oxide coating.

Synthesis of Uniformly Sized Bi0.5Sb1.5Te3.0 Nanoparticles via Mechanochemical Process and Wet-Milling for Reduced Thermal Conductivity.

In this study, Bi0.5Sb1.5Te3.0 (BST) nanoparticles (NPs) with high crystallinities were synthesized via a mechanochemical process (MCP). X-ray diffraction (XRD), and Raman and X-ray photoelectron spectroscopy (XPS) spectra of the BST NPs showed that the Bi, Sb, and Te powders successfully formed BiSbTe phase and transmission electron microscopy (TEM) images, verifying the high crystallinity and smaller size, albeit agglomerated. The as-synthesized BST NPs with agglomerated clusters were ground into smaller sizes of approximately 41.8 nm with uniform distribution through a simple wet-milling process during 7 days. The thermal conduction behaviors of bulk alloys fabricated by spark plasma sintering (SPS) of the BST NPs were studied by comparing those of samples fabricated from as-synthesized BST NPs and a BST ingot. The thermal conductivities (κ) of the BST nanocomposites were significantly reduced by introducing BST NPs with smaller grain sizes and finer distributions in the temperature range from 300 to 500 K. The BST nanocomposites fabricated from wet-milled BST NPs offered ultralow κ values of 0.84 W m−1 K−1 at approximately 398 K.