We introduced a modified pressureless sintering strategy by SPS with a new T-shape die and tapered punches, which helps the evaporation of melted Al and reduces the sample sticking with the inner wall of the die. Thus...
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We introduced a modified pressureless sintering strategy by SPS with a new T-shape die and tapered punches, which helps the evaporation of melted Al and reduces the sample sticking with the inner wall of the die. Thus, the die breaking risk in the sintering process or the de-molding process is avoided at all. At a low temperature and short holding time, a high purity of Cr_2 AlC was obtained in this SPS process from the optimization of different molar ratios of raw materials. Simultaneously, the high porosity of the as-obtained sample was also a distinguishing feature worth noticing. The reaction mechanism for this process was also discussed in detail. This study presented a new venue for future development of high purity "MAX" materials and others related materials by a modified pressureless sintering strategy.
Directly harvesting solar power without traditional solar cells represents an efficient solution to the current energy challenges. Photo-rechargeable batteries (PRBs) are receiving intense interest as they eliminate t...
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Lithium metal anode with high theoretical capacity is considered to be one of the most potential anode materials of the next generation. However, the growth of lithium dendrite seriously affects the application of lit...
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Lithium metal anode with high theoretical capacity is considered to be one of the most potential anode materials of the next generation. However, the growth of lithium dendrite seriously affects the application of lithium metal anode and the development of lithium metal batteries(LMBs). Herein, an ultrathin Li3N film modified separator to homogenize the lithium ions and protect the lithium metal anode was reported. Due to the intrinsic properties of Li3N, the functional separator possessed good thermal stability, mechanical properties and electrolyte wettability, and the homogenization of the lithium ion was realized without increasing the interface impedance. With this functional separator, the Li/Li symmetrical cell could achieve a long cycle with low overpotential for 1000 h at a current density of 1 m A cm-2. Furthermore, when the full battery was assembled with Li FePO4and the discharge capacity could be maintained at 151 m Ah g-1after 400 cycles at 1 C. In addition, the full battery also showed good rate performance, and provided a high discharge capacity of 114 m Ah g-1at 5 C.
Two isomeric fluorene-based heteroundecenes of bis(thienocyclopenthieno[3,2-b]thieno)fluorene(BT2T-F)and bis(dithieno[3,2-b:2’,3’-d]thiophene)cyclopentafluorene(B3T-F)have been designed and *** side chains of 4-hexy...
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Two isomeric fluorene-based heteroundecenes of bis(thienocyclopenthieno[3,2-b]thieno)fluorene(BT2T-F)and bis(dithieno[3,2-b:2’,3’-d]thiophene)cyclopentafluorene(B3T-F)have been designed and *** side chains of 4-hexylphenyl anchor on the 5th and 8th positions in B3T-F while on the 4th and 9th positions in BT2T-F,in which the former is closer to the center of the fused *** corresponding acceptor-donor-acceptor(A-D-A)type small molecule acceptors(SMAs)of BT2T-FIC and B3T-FIC were prepared by linking BT2T-F and B3T-F as fused ring donor units with the acceptor unit of 2-(5,6-difluoro-3-oxo-2,3-dihydroinden-1-ylidene)malononitrile(IC-2F),respectively.B3T-FIC presents a superior crystallinity with intense face-on π-π stacking in its neat film while BT2T-FIC is more *** blended with PBDB-T-2Cl as a polymer donor,the optimized PBDB-T-2Cl:BT2T-FIC device exhibits an averaged power conversion efficiency(PCE)of 10.56%while only 7.53%in the PBDB-T-2Cl:B3T-FIC *** improved short-circuit current(J_(sc))and fill factor(FF)of the PBDB-T-2Cl:BT2T-FIC device are the main contribution of its higher performance,which is attributed to its more efficient and balanced charge transport and better carrier recombination *** that BT2T-FIC blend and B3T-FIC blend films both take a preferential face-on orientatedπ-πstacking with comparable distances,the suitable SMA domain size obtained in the BT2T-FIC blend could account for its more efficient photovoltaic *** results highlight the importance of side-chain strategy in developing efficient SMAs with huge fused ring cores.
A high-pressure hot-pressing process was applied to densify a commercial boron carbide-titanium diboride (B4C-TiB2) powder *** fully dense (98.6%) materials were obtained at 1700℃ under a pressure of *** to the sinte...
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A high-pressure hot-pressing process was applied to densify a commercial boron carbide-titanium diboride (B4C-TiB2) powder *** fully dense (98.6%) materials were obtained at 1700℃ under a pressure of *** to the sintering temperature required to achieve similar results when a pressure of only 30MPa was applied,the sintering temperature was found to decrease by about 200℃ under pressure of 100 *** of the thermodynamics and microstructure showed that the plastic deformation of the B4C grains induced by high pressure dominated the densification mechanism when high pressure was ***,higher pressure resulted in remarkably improved mechanical properties of the composites,which could be traced back to the generation of stacking faults in the B4C grains and aggregation of TiB2.
The densification and the structure evolution of the plasma activated sintered(PAS sintered)ZrB_(2)-ZrO_(2) composite via the ZrO_(2)-coated ZrB_(2) powder(ZrB_(2)@ZrO_(2))prepared by in situ passivation method were *...
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The densification and the structure evolution of the plasma activated sintered(PAS sintered)ZrB_(2)-ZrO_(2) composite via the ZrO_(2)-coated ZrB_(2) powder(ZrB_(2)@ZrO_(2))prepared by in situ passivation method were *** composition and microstructure were characterized by XRD,Raman,SEM,and EDS *** coated powder has excellent sintering *** relative density of the composite reaches above 90%at 1200℃,and the main sintering process occurs between ZrO_(2) *** at above 1500℃,the relative density reaches above 95%and the main sintering process occurs between ZrB_(2) and ZrO_(2) *** the increase of ZrO_(2) coating content,the structure of the sintered body changes from ZrB_(2) continuous network structure to island *** the content is 20%,an island structure is *** the ZrO_(2) content further causes the overheating of ZrO_(2).Thus,the best sintering performance reaches when the coating content is 20wt%.
Titanium diboride ceramic was produced via spark plasma sintering(SPS)using finer TiB_(2)powder made by high-speed planetary ball *** effects of ball milling parameters on the composites and particle size of TiB_(2)po...
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Titanium diboride ceramic was produced via spark plasma sintering(SPS)using finer TiB_(2)powder made by high-speed planetary ball *** effects of ball milling parameters on the composites and particle size of TiB_(2)powder were *** was shown that the average particle size of TiB_(2)powder decreased from 5.8 to 1.59μm and the wear rate of WC balls was 1.58 wt%,when the ball-to-powder weight ratio(BPR),the rotary speed and milling time and were 10:1,600 rpm and 20 min,*** content of WC in TiB_(2)powder can be limited below 4.58 vol%by optimizing the milling *** sintering temperature of TiB_(2)powder milled can be decreased obviously,and the mechanical properties are evidently improved and the microstructure becomes more homogeneous when the powder of TiB_(2)becomes *** relative density,hardness,bending strength,and fracture toughness of the TiB_(2)ceramic fabricated at 1700℃reach the optimal values,which are 98.13%,19.14 GPa,756 MPa,and 5.71 MPa·m~(1/2),*** decrease of TiB_(2)particle size and the introduction of WC are the potential reasons for the improvement of TiB_(2)ceramic performance.
A novel fused nonacyclic monomer of dithieno[6,5-b:10,11-b']-8 H-cyclopentyl[1,2-b:4,3-b']diphenanthrene(DTCPDP) was synthesized by combining the structural features of ladder-type and multiple fused multi-cycli...
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A novel fused nonacyclic monomer of dithieno[6,5-b:10,11-b']-8 H-cyclopentyl[1,2-b:4,3-b']diphenanthrene(DTCPDP) was synthesized by combining the structural features of ladder-type and multiple fused multi-cyclic aromatics. DTCPDP has a single sp3-hybridized carbon bridge between fused multi-cyclic aromatics. The copolymerization of DTCPDT with the electron accepting unit of 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole(DTBT) via Stille coupling afforded a novel donor-acceptor(D-A) alternating copolymer PDTCPDT-DTBT. The copolymer exhibited good chemical and thermal stabilities, with an optical band gap of 1.82 eV and a low-lying highest occupied molecular orbital(HOMO) energy level of-5.32 eV. When the copolymer was incorporated into polymer: fullerene(PC_(71)BM) blends to fabricate bulk heterojunction polymer solar cell devices, the devices exhibited a moderate maximum power conversion efficiency(PCE) of 5.90%.
New layered perovskites, KSr2Nb3O10 and two new protonated niobates HSr2 Nb3O10·1.2H2O and HSr2Nb3O10,were synthesized by solid state reaction and ion-exchange reaction. These new compounds -were characterized by...
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New layered perovskites, KSr2Nb3O10 and two new protonated niobates HSr2 Nb3O10·1.2H2O and HSr2Nb3O10,were synthesized by solid state reaction and ion-exchange reaction. These new compounds -were characterized by EPMA, AAS, XRD, IR, DTA and so on. The structure may be described as treble perovskite sheets [Sr2Nb3O10]- interleaved with K+ ,H3O + or H+. These new compounds are new members of the Dion-Jacob-sonseries with n=3 for the general formula M[An-1 NbnO3n+1], and their indexed X-ray powder diffraction data were first reported in the paper.
Ceramic and polytetrafluoroethylene composites as dielectric materials have a low dielectric loss at high frequency and play an important role in the modern communication ***,room temperature phase transformation of P...
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Ceramic and polytetrafluoroethylene composites as dielectric materials have a low dielectric loss at high frequency and play an important role in the modern communication ***,room temperature phase transformation of PTFE resins,which is accompanied by a large volume change(>400 ppm/℃),seriously affects the dimensional stability and performance stability of *** LD125 modified glass fiber(GF)was introduced to the CaO-Li2 O-Sm2O3-TiO2(CLST)/PTFE composite,to reduce the thermal expansion coefficient(CTE)of the *** tri-phase composites(CLST/PTFE/GF)show the low dielectric loss and excellent *** effect of GF content on the dielectric properties and CTE was also *** CLST/PTFE filled with 5%GF exhibits the best overall performance,which is a promising microwave dielectric material for microwave communication.
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