Reducing thermal conductivity while avoiding adverse interfacial reactions during sintering is crucial for improving the thermoelectric performance of Bi_(2)Te_(3)based composites.Inert ceramic nanoparticles are good ...Reducing thermal conductivity while avoiding adverse interfacial reactions during sintering is crucial for improving the thermoelectric performance of Bi_(2)Te_(3)based composites.Inert ceramic nanoparticles are good candidates for achieving this goal.In this study,we designed and prepared a series of p-type Bi_(0.5)Sb_(1.5)Te_(3)nanocomposites decorated with Y_(2)O_(3)ceramic nanoparticles via ball-milling dispersion and spark-plasma sintering.Owing to the chemical stability of the ceramics,no traces of atomic doping or interfacial reactions were observed.Transport measurements revealed that the Y_(2)O_(3)nanoparticles distributed along the grain boundaries acted as energy-dependent carrier-filtering centers to improve the scattering parameter and Seebeck coefficient,contributing to the elevated power factor even with a decreased electrical conductivity.Moreover,the incorporated Y_(2)O_(3)nanoparticles and various defect structures they induced effectively strengthened the phonon scattering and suppressed the lattice thermal conductivity.Consequently,a peak figure of merit(ZT)of 1.23 at 313 K was achieved for 0.4%Y_(2)O_(3)/Bi_(0.5)Sb_(1.5)Te_(3),which is 13%higher than that of the matrix.In addition,the Vickers hardness of the composite material was 35%higher than that of the matrix.This study demonstrates the effectiveness of ceramic nanoparticles in synergistic ally improving the thermoelectric and mechanical properties,which may be further extended to other thermoelectric systems.展开更多
ZrO_(2)-strengthened porous mullite insulation materials were prepared by foaming technology utilizing ZrSiO_(4) and Al_(2)O_(3) as primary materials and Y_(2)O_(3) as an additive.The effects of Y_(2)O_(3) contents on...ZrO_(2)-strengthened porous mullite insulation materials were prepared by foaming technology utilizing ZrSiO_(4) and Al_(2)O_(3) as primary materials and Y_(2)O_(3) as an additive.The effects of Y_(2)O_(3) contents on the phase composition,microstructure,mechanical properties,and heat conductivity of the porous mullite insulation materials were investigated.A suitable Y_(2)O_(3) content could promote phase transition of monoclinic ZrO_(2)(m-ZrO_(2))to tetragonal ZrO_(2)(t-ZrO_(2)),reduce pore size,and improve the strengths of as-prepared specimens.The cold crushing strength and bending strength of as-prepared specimens with a 119µm spherical pore size using 6 wt.%Y_(2)O_(3) were 35.2 and 13.0 MPa,respectively,with a heat conductivity being only 0.248 W/(m K).展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.11834012 and 52130203)。
文摘Reducing thermal conductivity while avoiding adverse interfacial reactions during sintering is crucial for improving the thermoelectric performance of Bi_(2)Te_(3)based composites.Inert ceramic nanoparticles are good candidates for achieving this goal.In this study,we designed and prepared a series of p-type Bi_(0.5)Sb_(1.5)Te_(3)nanocomposites decorated with Y_(2)O_(3)ceramic nanoparticles via ball-milling dispersion and spark-plasma sintering.Owing to the chemical stability of the ceramics,no traces of atomic doping or interfacial reactions were observed.Transport measurements revealed that the Y_(2)O_(3)nanoparticles distributed along the grain boundaries acted as energy-dependent carrier-filtering centers to improve the scattering parameter and Seebeck coefficient,contributing to the elevated power factor even with a decreased electrical conductivity.Moreover,the incorporated Y_(2)O_(3)nanoparticles and various defect structures they induced effectively strengthened the phonon scattering and suppressed the lattice thermal conductivity.Consequently,a peak figure of merit(ZT)of 1.23 at 313 K was achieved for 0.4%Y_(2)O_(3)/Bi_(0.5)Sb_(1.5)Te_(3),which is 13%higher than that of the matrix.In addition,the Vickers hardness of the composite material was 35%higher than that of the matrix.This study demonstrates the effectiveness of ceramic nanoparticles in synergistic ally improving the thermoelectric and mechanical properties,which may be further extended to other thermoelectric systems.
基金supported by the Natural Science Foundation of Anhui Provincial Education Department(2023AH051130 and KJ2021ZD0040)the University Synergy Innovation Program of Anhui Province(GXXT-2019-015)+2 种基金National Natural Science Foundation of China(51972002)the Student Research Training Program(SRTP)of Anhui University of Technology(S202310360191)National Innovation and Entrepreneurship Training Program for College Students(202210360023).
文摘ZrO_(2)-strengthened porous mullite insulation materials were prepared by foaming technology utilizing ZrSiO_(4) and Al_(2)O_(3) as primary materials and Y_(2)O_(3) as an additive.The effects of Y_(2)O_(3) contents on the phase composition,microstructure,mechanical properties,and heat conductivity of the porous mullite insulation materials were investigated.A suitable Y_(2)O_(3) content could promote phase transition of monoclinic ZrO_(2)(m-ZrO_(2))to tetragonal ZrO_(2)(t-ZrO_(2)),reduce pore size,and improve the strengths of as-prepared specimens.The cold crushing strength and bending strength of as-prepared specimens with a 119µm spherical pore size using 6 wt.%Y_(2)O_(3) were 35.2 and 13.0 MPa,respectively,with a heat conductivity being only 0.248 W/(m K).
