Reduction In Thermal Conductivity Research Articles

Effect of lattice distortion in high-entropy RE2Si2O7 and RE2SiO5 (RE=Ho, Er, Y, Yb, and Sc) on their thermal conductivity: Experimental and molecular dynamic simulation study

High-entropy materials are considered to be born with lattice distortion, which is still lack of comprehensive investigation in rare earth silicates to date. In this paper, we confirmed the existence of lattice distortions in high-entropy rare-earth silicates via experiments and molecular dynamic simulations. The effects of the lattice distortion on the thermophysical properties are elucidated. Simulation results indicate the lattice distortion is present in both cation and anion sublattice, leading to the compressing and stretching of atomic bond as well as fluctuation of atomic bond strength. Accordingly, lattice distortion in the Si and O sublattice is also verified by the Raman spectra. Furthermore, the thermal conductivity of high-entropy rare earth silicates remarkably reduces and exhibits glass-like behavior, which is confirmed by experiments in cooperation with molecular dynamic simulations. Simulation also reveals that the lifetimes and group velocities of vibrational modes are significantly reduced by lattice distortion, which result in the reduction of overall thermal conductivity of high-entropy rare-earth silicates.

Performance of lightweight foamed concrete partially replacing cement with industrial and agricultural wastes: Microstructure characteristics, thermal conductivity, and hardened properties

The production of eco-friendly concrete has been made possible by reusing agricultural and industrial wastes. This paper presents an experimental investigation of the characteristics of lightweight foamed concrete (LWF) produced from a protein-based foaming agent and including granulated blast furnace slag (GGBS), fly ash (FA), rice husk ash (RHA) and palm oil fuel ash (POFA) at various substitution levels (0, 10 %, 20 %, 30 %, 40 %, 50 %, and 60 %) with cement. By executing a slump test, the fresh characteristics of mixes were assessed. In addition, a total of 25 different LWF mixtures were produced and tested for their porosity, bulk density, compressive strength, bending strength, splitting tensile strength, water absorption, ultrasonic pulse velocity (UPV), and thermal conductivity. To elucidate the causes for the experimental findings acquired, microstructural analysis was also performed. The findings indicate that the GGBS, FA, RHA, and POFA ratios of the LWFs increased due to a reduction in slump, porosity, water absorption, bulk density, and thermal conductivity up to 40 % GGBS, 30 % FA, 20 % RHA, and 30 % POFA. However, the compressive strength, bending strength, splitting tensile strength, UPV were raised up to 40 % GGBS, 30 % FA, 20 % RHA and 30 % POFA as substitution for cement. LWF containing 40 % GBS as a cement substitution also demonstrate larger compressive strength, bending strength, splitting tensile strength, and ultrasonic pulse velocity in comparison with the control, 30 % FA, 20 % RHA, and 30 % POFA LWF. The findings are promising and reveal a major opportunity for developing eco-friendly LWF by partially substituting cement with GGBS and FA industrial by-product material, RHA and POFA agricultural waste materials as well.

Optimizing Thermoelectric Performance of Tellurium via Doping with Antimony and Selenium.

Forming solid solutions is one of the most effective strategies to suppress the thermal conductivity of thermoelectric materials. However, the accompanying increase in impurity ion scattering usually results in an undesirable loss in hall mobility, negatively impacting the electrical transport properties. In this work, a tellurium-selenium (Te-Se) solid solution with trace antimony (Sb) doping was synthesized via the high pressure and high temperature method. It was found that slight Se doping into the Te sites not only had no impact on the hall mobility and carrier concentration, but also enhanced the density-of-state effective mass of Sb0.003Te0.997, leading to an enhanced power factor near room temperature. Additionally, the presence of Se doping caused a significant reduction in the phonon thermal conductivity of Te due to fluctuations in the mass and strain field. The lowest phonon thermal conductivity was as low as ~0.42 Wm-1K-1 at 600 K for Sb0.003Se0.025Te0.972, which approached the theoretical minimum value of Te (~0.28 Wm-1K-1). The effects of Se doping suppressed thermal conductivity, while Sb doping enhanced the power factor, resulting in a larger ZT of ~0.94 at 600 K. Moreover, these findings demonstrate that Sb and Se doping can effectively modulate the electrical and thermal transport properties of Te in a synergistic manner, leading to a significant increase in the average ZT across a wide temperature range.

Thermoelectric properties of Yb-La-Nb-doped SrTiO3

Yb2Ti2O7 exhibits ferromagnetic and magnetic properties, which are expected to exert a discernible influence on the thermoelectric properties of SrTiO3 composite. The La-Yb-Nb-doped SrTiO3 powders, synthesized via the hydrothermal method, were prepressed and then buried in carbon powder before being sintered in a muffle furnace at 1573 K for 5 h. The Yb dopant precipitated during the sintering process, leading to the in-situ formation of Yb2Ti2O7. The content of Yb2Ti2O7 increased with an increasing Yb concentration, resulting in a reduction in thermal conductivity and grain boundary potentials, and an increase in the peak electrical conductivity. The La and Nb dopants affect the electrical conductivity and the Seebeck coefficient. Therefore, by controlling the La, Nb, and Yb ratios, the La8Yb2Nb15 sample achieved the largest power factor (PF) value of 0.9 mWm−1K−2 and a low thermal conductivity of 2.9 W m−1K−1, resulting in a high ZT value of 0.32 at 1000 K.

A homogeneous composite approach for improved thermoelectric performance: Repressing lattice thermal conductivity in substoichiometric WO2.90 and WO2.72

Nanostructured phonon-glass thermoelectric materials are highly sought after for heat waste recovery applications. This work introduces a novel phonon-glass multi-phase ceramic material synthesized from sintered mixtures of two sub-stoichiometric tungsten oxides, WO2.90 and WO2.72. Notable measurements were recorded for our sample, denoted as 0.1WO2.72/0.9WO2.90, at 800 °C, with S2σ = 0.51 ± 0.03 mWm−1K−2, representing a tenfold increase compared to the base materials. The lattice thermal conductivity, already displaying phonon-glass characteristics, is further suppressed by the addition of the secondary WO2.72 pentacolumn phase, reaching its lowest value at 0.54 ± 0.25 Wm−1K−1. As a result, the ZT value is enhanced to twice the intrinsic value of the pristine phase. This study demonstrates a novel strategy for improving the thermoelectric performance of oxide-based materials by leveraging a synergistic relationship among several key factors, including phonon-glass nanostructures, tunable electrical properties, and the reduction of lattice thermal conductivity within a homogeneous composite system.

Enhanced reduction of thermal conductivity across kink dislocation textures in magnesium oxide

Enhanced reduction of thermal conductivity across kink dislocation textures in magnesium oxide

Strained Lamellar Structures Leading to Improved Thermoelectric Performance in Mg3Sb1.5Bi0.5.

Mg3Sb2-xBix solid-solutions represent an important class of thermoelectric (TE) materials due to their high efficiency and variable operating temperature range. Of particular significance for midtemperature applications is the Mg3Sb1.5Bi0.5 composition whose superior thermoelectric (TE) performance is attributed to the complex conduction band edge in conjunction with alloy dominated phonon scattering. In this work, we show that microstructure also plays a significant role in lowering the lattice thermal conductivity which in turn affects the overall TE performance (change in peak zT values between 1.1 and 1.4 have been observed). Temperature dependent TE properties of Mg3+xSb1.5Bi0.5 compositions with varying nominal Mg content (x = 0.2, 0.3, 0.4) have been studied. A marked reduction of the lattice thermal conductivity (κL) is observed in compositions with low nominal Mg content (x = 0.2), which is due to the presence of lamellar structures within the grains. These lamellar regions are isostructural to the matrix with a low misfit angle and represent compositional fluctuations in the Bi to Sb ratio. Both the size (200 nm-500 nm) and the interfacial strain contribute to the enhanced phonon scattering. A quantitative estimate of κL reduction due to these structures have been carried out using a mean free path (MFP) spectrum analysis which reveal a good match with experiments at room temperature. Further, the electrical properties are not influenced by these lamellar structures as observed from the similar power-factor (S2σ) and weighted mobilities in all of the compositions. This is due to their similar orientation to the adjacent matrix region. Thus, the zT parameter in the various compositions with similar carrier concentration can be significantly altered (∼25%) by adjusting the nominal Mg content. The results demonstrate that preferential phonon scattering by microstructure modification can be a new route for property improvement in Mg3+xSb2-yBiy solid-solutions.

Substrate-induced bonding asymmetry leading to strong phonon anharmonicity and largely reduced thermal conductivity of monolayer XS2 (X = Mo and W) from first-principles calculations

Thermoelectric materials have properties such as direct conversion of waste heat into electricity and environmental friendliness, which make them promising for renewable energy utilization, however, the lower conversion efficiency limits the large-scale application of thermoelectric materials. Monolayer transition metal dichalcogenides (TMDs) are candidates for thermoelectric materials due to their high power factor, but their higher thermal conductivity (TC) limits the further improvement of the figure of merit (ZT). Here, we employ first-principles calculations and solve the Boltzmann transport equation (BTE) to compare the lattice TC of free-standing monolayer XS2 (X = Mo and W) and monolayer XS2 supported on SiC (0001) and ZnO (0001) substrates. We find that the lattice TC of monolayer XS2 supported on SiC (0001) and ZnO (0001) substrates are sharply reduced. Especially supported on the ZnO (0001) substrate, the lattice TC of XS2 reduce by 65 %–70 %, which is expected to improve the thermoelectric properties of monolayer XS2. In addition, we report the underlying cause of this significant reduction in TC. Firstly, the substrate drives softening of the acoustic branch, which leads to a decrease of phonon group velocity in the low-frequency and an enhancement of the three-phonon scattering. Then, the asymmetric bonding of XS2 is induced by the substrates, which enhance phonon anharmonicity and reduce the phonon lifetime. Our results demonstrate that the lattice TC of monolayer XS2 can be tuned by adjusting the substrate, which has certain reference values for the thermoelectric design of XS2.

Tuning the microstructure of polyurethane foam using nanocellulose for improved thermal insulation properties through an efficient dispersion methodology

AbstractNanocellulose is explored as an eco‐friendly cell modifier and reinforcer for improving the thermal insulation and mechanical performance of rigid polyurethane foam (RPUF). In this study, we report on a promising method for achieving ‘solvent‐free' dispersion of cellulose nanocrystals (CNCs) into polyether polyol for the production of RPUF. This was achieved through wet grinding of CNC powder in polyol in an agitator bead mill and the dispersion of CNCs in polyol was superior to classical ultrasonication. While the improvements (reduction) in thermal conductivity, due to the nucleation effect of CNCs, in the RPUF from the milling method is comparable to that from the ultrasonication method, it should be noted that it was achieved despite of a reduction in closed cell content (~80%) and at a similar average cell size. This effect has been attributed to either superior dispersion quality of the milling method and/or involvement of a zirconium impurity within the CNC‐RPUF.Research Highlights Enhanced properties of polyurethane foam using well‐dispersed nanocellulose. Superior dispersion of nanocellulose in polyol using agitator bead mill. Involvement of zirconium for tuning microstructure of polyurethane foam.

Thermoelectric properties of B-doped nanostructured bulk diamond with lowered thermal conductivity

Diamond exhibits high wear resistance and high chemical resistance. If diamond exhibits high thermoelectric performance, the thermoelectric application will be expanded for various situations such as the use of friction heat on turbines. However, bulk diamond exhibits low electrical conductivity and high thermal conductivity, leading to the low thermoelectric performance. In this study, to solve the above problem, we propose a strategy of heavy impurity doping in nanostructured bulk diamond which brings two things: (1) higher thermoelectric power factor, and (2) phonon scattering enhancement at impurities and nanostructure interfaces reducing the thermal conductivity drastically. We investigate the thermoelectric properties of heavily B-doped nanostructured bulk diamonds prepared by direct conversion sintering under ultra-high pressure and temperature using B-doped graphite as a starting material. This nanostructured bulk diamond exhibited high electrical conductivity due to heavy B doping, resulting in high power factor of 4 μWcm−1 K−2 at 1050 K. Furthermore, we found that this nanostructured bulk diamond exhibited drastic thermal conductivity reduction, resulting in quite low thermal conductivity among bulk diamond ever reported. This comes from phonon scattering both at nanostructure interfaces and by substitutional B atoms. From these results, the present study would be informative for expanding thermoelectric application to various situations such as the use of friction heat.

High thermoelectric power factor in Bi1.2Na0.8Te3/Ag-NPs composites

Novel matrix composites of Na-doped Bi2Te3 with Ag nanoparticles included were prepared and studied in this article. Alloys of Bi1.2Na0.8Te3 were prepared by direct temperature melting at high temperature. Ag nanoparticles were incorporated into the system at different amounts. X-ray diffraction and scanning electron microscopy were used to examine structural, crystallographic, and morphological aspects The addition of silver caused a shift in the structure, resulting in the division of the structure into two main sections. Initially, Bi1.2Na0.8Te0.6 phase was successfully doped with Ag without any changes. Then, the phase exhibited a notable shift, due to a change in the lattice parameters, as the amount of Ag increases to x = 0.06 and 0.08 wt%. A change in the atomic order is caused by the successful replacement of Ag inside composites, which created a new structure of Bi1.2Na0.8AgxTe3. The layered bulk structure was observed by SEM investigations. Various particle sizes were observed revealing the incorporation of Ag-nanoparticles. The thermoelectric properties were studied between 273K and 473K. The four-probe approach was used to calculate electrical conductivity, and a typical differential technique was used to get the Seebeck coefficient. The Ag-incorporated Bi1.2Na0.8Te3 alloys showed quite a higher Seebeck coefficient, in comparison to the Ag-free compound. The thermoelectric power factor was calculated, and the maximum value was obtained at 30 × 102 μW/mK2 for Bi1.2Na0.8Te0.6 at room temperature. The value is quite high and encouraging for applications in thermoelectric devices. A considerable reduction in overall thermal conductivity of the studied system was observed after the addition of Ag-NPs, according to thermal conductivity studies. The lowest thermal conductivity was achieved by adding Ag-NPs at 0.08% in the Bi1.2Na0.8Te3/Ag0.08 composite. An interesting room temperature-ZT was achieved at 0.56.

Understanding of EPS beads on mechanical properties and void morphology of a CO2-solidified foam concrete based on solid wastes

Two major issues of EPS doped concrete are apparent reduction in compressive strength associated with the presence of EPS-formed artificial defects and ultra-light weight related easy segregation in the mixes, even though the thermal conductivity of composites shows a satisfactory reduction. This paper presents a composite lightweight concrete by introducing EPS into a solid waste (carbide slag and quartz sand tailings) prepared industrial grade γ-C2S-based foam concrete (CFC) to partially replace foam-formed voids. Results show that the partially EPS-substituted CFC with reasonable EPS parameters (Especially 1 mm in diameter and 5 wt% in content) exhibits a notable improvement in compressive strength (24.3%) while accompanied by the reduction in sorptivity, drying shrinkage and thermal conductivity. This is attributed to the fact that the EPS can effectively improve the foam stability by delaying foam drainage velocity due to its hydrophobicity and discrete smooth surface during the pre-curing procedure, which results in a refinement of void morphology and distribution as well as the optimized interfacial transition zone (ITZ). Accompanied by the compact inner surface and optimized ITZ, leading to a lower drying shrinkage, thermal conductivity, and also a reduction in sorptivity due to the increasing of tortuous path for the capillary flow. Moreover, magnesium slag (MS) containing dicalcium silicate mineral phase is also used to prepare MS-based CFC to further reduce costs and achieve the resource utilization of solid waste and a large amount of CO2 storage, which contributes to the sustainable development of CFC.

Fire-Resistant Bio-based Polyurethane Foams Designed with Two By-Products Derived from Sugarcane Fermentation Process

There is a growing interest in replacing conventional fossil-based polymers and composites with waste-based materials and fillers for environmental sustainability. This study designed water-blown polyurethane rigid foams using two by-products from the Amyris fermentation process of producing β-farnesene. The distillation residue (FDR) served as the main polyol component in the foam’s formulation (PF), supplemented with 4.5% sugarcane bagasse ash (SCBA) as a fire-retardant filler (PFA). The study assessed the impact on foam properties. Based on the analysis of all compiled data (foam structure, mechanical, and thermal properties), it can be inferred that ash particles acted as nucleating points in the reaction media, leading to a reduction in foam density (from 134 to 105 kg/m3), cell size (from 496 to 480 nm), and thermal conductivity. The absence of chemical interaction between the ash filler and the polyurethane matrix indicates that the ash acts as a filler with a plasticizing effect, enhancing the polymer chain mobility. As a result, the glass transition temperature of the foam decreases (from 74 to 71.8 ºC), and the decomposition onset temperature is delayed. Although, the incorporation of 4.5% SCBA (grain size below 250 μm) was ineffective in the increment of the compressive strength, that small amount was enough to increase the foam’s specific strength from 1009 to 1149 m2/s2 suggesting that other factors (e.g. polyol feedstock, grain size, ash packing, etc.) are yet to be accounted. The flammability test results indicate that sugarcane bagasse ash improved the foam performance, reducing burning time from 251 to 90 s, time of extinguishment from 255 to 116 s, and burning length from 132 to 56.7 mm, meeting the fire protection standard UL 94, class HB. Despite the need for further improvement and detailed flammability evaluation, the results support the notion that polyurethane foams from renewable waste by-products offer a sustainable alternative to both edible and fossil-based sources. Additionally, sugarcane bagasse ash can be a suitable silica source for reinforcing composites with reduced flammability, potentially replacing harmful halogenated chemicals used for the same purpose.Graphical

Mechanism of Thermoelectric Performance Enhancement in CaMg2 Bi2 -Based Materials with Different Cation Site Doping.

Chemical bonds determine electron and phonon transport in solids. Tailoring chemical bonding in thermoelectric materials causes desirable or compromise thermoelectric transport properties. In this work, taking an example of CaMg2 Bi2 with covalent and ionic bonds, density functional theory calculations uncover that element Zn, respectively, replacing Ca and Mg sites cause the weakness of ionic and covalent bonding. Electrically, Zn doping at both Ca and Mg sites increases carrier concentration, while the former leads to higher carrier concentration than that of the latter because of its lower vacancy formation energy. Both doping types increase density-of-state effective mass but their mechanisms are different. The Zn doping Ca site induces resonance level in valence band and Zn doping Mg site promotes orbital alignment. Thermally, point defect and the change of phonon dispersion introduced by doping result in pronounced reduction of lattice thermal conductivity. Finally, combining with the further increase of carrier concentration caused by Na doping and the modulation of band structure and the decrease of lattice thermal conductivity caused by Ba doping, a high figure-of-merit ZT of 1.1 at 823 K in Zn doping Ca sample is realized, which is competitive in 1-2-2 Zintl phase thermoelectric systems.

Strengthening and thermal conductivity behaviors of cast Cu-La-Zn alloys

A new Cu-La-Zn alloy system with high thermal conductivity was developed for die casting, and the thermal conductivity of this alloy system was 200-300 W/(m·K), which was twice as that of ordinary brass. The effects of Cu6La intermetallic compounds and Zn solute atoms on the strengthening and thermal conductivity behaviors were quantitatively studied in as-cast binary Cu-La (2.0-4.5 wt.% La) and ternary Cu-2La-xZn (0-3.0 wt.% Zn) alloys, respectively. The results showed that for the increase of per 1 wt.% La or Zn, the thermal conductivity decreased by about 34 W/(m·K). In Cu-2La-xZn alloys, the lattice constant of α-Cu matrix increased from 3.6163 to 3.6239 Å. Due to the solid solution strengthening of Zn atoms, the hardness of the α-Cu matrix showed a parabolically increasing tendency, from 1.495 to 1.597 GPa. According to the calculations of the Maxwell-Eucken model based on the microstructure, the thermal conductivity of Cu6La phase was determined to be about 35.37 W/(m·K), and the reduction in thermal conductivity of α-Cu matrix caused by Zn solute atoms was quantified to be 51.38 W/(m·K) per 1.0 at.% Zn increase.

Developing fired clay bricks by incorporating scrap incinerated waste and river dredged sediment

The global extraction of several billions of clean clay resources, which destroy millions square meters of land, is triggering environmental problems. Incorporating different dosages of incinerated waste or dredged sediment in bricks production has been studied by many researchers. Research articulating the combined effect of incinerated waste material (IWM) and river dredged sediments (RDS) addition on the performance of bricks is scarce. This paper aims to present findings on the engineering performance of fired bricks developed with the addition of IWM and RDS. In this regard, bricks were made with 5 wt% IWM and different dosages of RDS (i.e., 0 – 15 wt%). Physical, durability, mechanical, thermal and microstructure of the developed bricks is examined. Bricks’ shrinkages were found meeting quality performance criterion in the 1.42 – 4.11% range. The highest bulk density of 1.85 g/cm3 permit to classify bricks obtained as lightweight. Water absorptions were mostly within the acceptable 20% tolerance level postulating the developed bricks high durability standard. Compressive strength reductions, which were confined within 5.28 and 21.57 MPa, showed the developed bricks applicability to structural weight-supporting construction as well as specialized engineering construction works. The 40.5% thermal conductivity reduction in WB15 bricks (at 800 °C) theorized its suitability for thermal insulation construction. Mineralogical and morphological analyses of fired bricks clearly showed kaolinite polymorphic phase transformation, which contributed to the different morphologies in the brick matrices. Consequently, reuse of IWM and RDS offered a chance to advance sustainable use of scarce clay resources in lightweight and thermal insulation brick production.

Enhanced thermoelectric performance of Bi2-xCuxS3 by hydrothermal synthesis and spark plasma sintering

Bi2S3 has been considered as a promising medium temperature thermoelectric material due to its low thermal conductivity and cost-effective features. However, the intrinsically poor electrical conductivity of Bi2S3 still limits its further thermoelectric applications. In this work, we optimize the thermoelectric performance of Bi2S3 using Cu doping via a facile hydrothermal method combined with spark plasma sintering. A well-tuned carrier concentration of 1.2 × 1019 cm−3 and electrical conductivity of 47 S cm−1 at 523 K was attained, which is attributed to the increased electrons by Cu doping. In addition, the appeared micro-nano pores in both Bi2S3 and Cu doped Bi2S3 samples after spark plasma sintering benefits the reduction of lattice thermal conductivity (κl). The Bi1.985Cu0.015S3 sample exhibited the lowest κl of 0.405 W m−1 K−1 at 573 K, which is the lowest value as far as we know in the reported Cu doped Bi2S3 materials at the same temperature. Finally, A maximum ZT value of 0.3 at 573 K was achieved in Bi1.985Cu0.015S3 sample. This study provides a new strategy to achieve low κl and high ZT value in Bi2S3-based thermoelectric materials.

Characterisation and thermal improvement of adobe walls from earth-straw lightweight panels

Soil as a building material has great potential in terms of low embodied energy, although the great diversity of soils means that more research is needed to characterise them with precise values. In addition, their high thermal transmittance is one of the main drawbacks of earths, so the incorporation of agrowastes could imply a reduction of thermal conductivity without any harm to the embodied energy. Three types of agrowastes have been evaluated: long and short wheat straw fibres and a sawdust. These three fibres were mixed with barbotine to reduce the amount of solid material in the mixture. These panels were compared with the performance of a 20-cm-thick adobe wall. The thermal transmittance of the materials was analysed and the results showed that panel 2 with short wheat straw fibres performed well as a thermal insulation board with a thermal conductivity of λ = 0.05 W/mK.Graphical abstract

Computational thermal analysis of a latent heat storage unit augmented with porous fins

Phase change material (PCM)-based thermal energy storage systems provide a large capacity to store energy; however, PCMs are impaired by relatively low thermal conductivity. Presently, the use of copper foam annular fins was numerically investigated in a PCM-based thermal storage unit. Six copper annular fin cases were studied: three cases with 10 fins and three cases with 20 fins. The 10 and 20 fin cases included configurations with solid fins and two porous fin cases including 40 PPI with porosities of 90.91% and 97.20%. Simulations were completed in ANSYS-Fluent to examine the effects of porous annular fins on the charging and discharging cycles of a vertical shell-tube unit with Rubitherm RT-55 PCM. The cases were compared based on required time to completely melt and solidify the PCM, along with the energy response of the system. Charging times for the solid, 90.91% porous, and 97.20% porous 10 fin cases were 11.89, 19.92, and 23.33 h. The same cases discharged the system in 11.39, 19.50, and 27.28 h. Equal cases with 20 annular fins charged the system in 10.00, 22.78, and 28.08 h, and discharged in 9.08, 18.14, and 26.22 h. Increased convection from porosity cannot overcome reduction of effective thermal conductivity.

The effect of in-situ TiB2 segregated network structure on the thermoelectric properties of spark plasma sintered B4C ceramics

Different amounts of TiC particles between 1 and 7.5 vol% were coated on spray-dried B4C granules with a simple dry particle coating method, then spark plasma sintered at 2200 °C under vacuum, forming 3D-segregated network structures (SNS) of in-situ TiB2 between 1 and 9 vol%, to improve the thermoelectric (TE) performance of B4C. With the in-situ TiB2-SNS, a maximum ZT of 8.02×10−2 was achieved with 2 vol% TiB2-SNS at 923 K by simultaneous improvement of electrical conductivity due to the electrically conductive network of TiB2 and reduction of thermal conductivity due to the increased phonon scattering, improving the ZT of monolithic B4C by an impressive ≈ 120%. Higher quantities of TiC addition proved inefficient in improving the TE performance; by forming 9 vol% TiB2, ≈ 945% increase in electrical conductivity was achieved; however, the Seebeck coefficient was affected negatively, causing a drastic decrease in the ZT value.