Reversible solid oxide cells(RSOCs)are capable of converting various energy resources,between electricity and chemical fuels,with high efficiency and flexibility,making them suitable for grid balancing and renewable e...Reversible solid oxide cells(RSOCs)are capable of converting various energy resources,between electricity and chemical fuels,with high efficiency and flexibility,making them suitable for grid balancing and renewable energy consumption.However,the practical application of RSOCs is still limited by the insufficient activity and stability of the electrodes in different operating modes.Herein,a highly efficient symmetrical electrode composed of La_(0.3)Sr_(0.6)Ti_(0.1)Co_(0.2)Fe_(0.7)O_(3-δ)(LSTCF)nanofibers and in situ exsolved Co_(3)Fe_(7) nanoparticles is developed for boosting the performance of RSOCs.The reversible phase transition,high activity and stability of the electrode have been confirmed by a combination of experimental(e.g.,transmission electron microscopy and X-ray absorption fine structure)and computational studies.Electrolyte-supported RSOCs with the symmetrical electrode demonstrate excellent catalytic activity and stability,achieving a high peak power density of 0.98 W cm^(-2)in the fuel cell mode using H_(2)as the fuel(or 0.53 W cm^(-2)using CH_(4)as the fuel)and a high current density of 1.09 A cm^(-2) at 1.4 V in the CO_(2)electrolysis mode(or 1.03 A cm^(-2)at 1.3 V for H_(2)O electrolysis)at 800℃while maintaining excellent durability for over 100 h.展开更多
A new lithium zincoborate Li_(6)Zn_(3)(BO_(3))_(4) has been successfully prepared via a high-temperature solution method.Li_(6)Zn_(3)(BO_(3))_(4) is composed of LiO4 and ZnO_(4) tetrahedra,and nearly coplanar BO3 unit...A new lithium zincoborate Li_(6)Zn_(3)(BO_(3))_(4) has been successfully prepared via a high-temperature solution method.Li_(6)Zn_(3)(BO_(3))_(4) is composed of LiO4 and ZnO_(4) tetrahedra,and nearly coplanar BO3 units.A facesharing LiO_(4) configuration was found in the title compound,and a comparison of Li-O configurations was systemically investigated for all Li-containing borates.Interestingly,Li_(6)Zn_(3)(BO_(3))_(4) has two reversible phase transitions at about 341 and 706℃,which implies that Li_(6)Zn_(3)(BO_(3))_(4) is a potential candidate as a phase change material.In situ high-temperature X-ray diffraction(XRD)and differential scanning calorimetry(DSC)analysis were used to verify the two reversible phase transitions.The linear optical properties were researched in detail using ab initio density functional theory(DFT).展开更多
Phase transition is common during (de)-intercalating layered sodium oxides, which directly affects the structural stability and electrochemical performance. However, the artificial control of phase transition to achie...Phase transition is common during (de)-intercalating layered sodium oxides, which directly affects the structural stability and electrochemical performance. However, the artificial control of phase transition to achieve advanced sodium-ion batteries is lacking, since the remarkably little is known about the influencing factor relative to the sliding process of transition-metal slabs upon sodium release and uptake of layered oxides. Herein, we for the first time demonstrate the manipulation of oxygen vacancy concentrations in multinary metallic oxides has a significant impact on the reversibility of phase transition, thereby determining the sodium storage performance of cathode materials. Results show that abundant oxygen vacancies intrigue the return of the already slide transition-metal slabs between O_(3) and P_(3) phase transition, in contrast to the few oxygen vacancies and resulted irreversibility. Additionally, the abundant oxygen vacancies enhance the electronic and ionic conductivity of the Na0.9Ni0.3Co0.15Mn0.05Ti0.5O2 electrode, delivering the high initial Coulombic efficiency of 97.1%, large reversible capacity of 112.7 mAh·g−1, superior rate capability upon 100 C and splendid cycling performance over 1,000 cycles. Our findings open up new horizons for artificially manipulating the structural evolution and electrochemical process of layered cathodes, and pave a way in designing advanced sodium-ion batteries.展开更多
Manipulating light polarization in birefringent crystals is central to photonic applications.However,controlling intrinsic optical anisotropy in a noninvasive manner remains challenging.Here,we report our discovery of...Manipulating light polarization in birefringent crystals is central to photonic applications.However,controlling intrinsic optical anisotropy in a noninvasive manner remains challenging.Here,we report our discovery of the polymorphism of the inorganic birefringent crystal KCe(SO_(4))_(2).P and P2_(1/c)-KCe(SO_(4))_(2) crystals can be obtained through polymorph-controllable synthesis.Interestingly,P-KCe(SO_(4))_(2) exhibits reversible phase transition during which the birefringence value varies by up to 50%.The material is highly stable and the birefringence alteration stimulated by thermally induced phase transition is reversible for over 10 cycles,demonstrating its potential as a birefringence switch.We reveal that the optical anisotropy of KCe(SO_(4))_(2) polymorphs primarily stems from the arrangement of [CeO_(9)] and [KO_(10)] structural units,as evidenced by the dipole moments and first principles calculations.Our work not only provides new insights into the controlled synthesis of polymorphic materials but also advances the development of tunable birefringent materials for integrated photonics.展开更多
A one-dimensional coordination polymer[(C_(2)H_(4)OH)C_(4)H_(9)NS]CdCl_(3)(1)with flexible N-(2-hydroxyethyl)thiomorpholinium cations coordinating to central metal Cd crystallized in a chiral space group P2_(1)2_(1)2_...A one-dimensional coordination polymer[(C_(2)H_(4)OH)C_(4)H_(9)NS]CdCl_(3)(1)with flexible N-(2-hydroxyethyl)thiomorpholinium cations coordinating to central metal Cd crystallized in a chiral space group P2_(1)2_(1)2_(1)and showed a reversible phase transition at 174.4/162.8 K,which corresponded to the second harmonic generation(SHG)activity and dielectric switching.The introduction of a thioether group enables 1 to adsorb Pd(II)metal ions and the SHG signal and dielectric switching disappeared after adsorption;hence,Pd(II)adsorption can be monitored by the measurements of SHG and dielectric switching.This study emphasizes the advantages of introducing functional groups into the phase transition materials and presents a new approach to design multifunctional materials.展开更多
Organic-inorganic metal halides(OIMHs)possessing switchable optical and electrical properties hold significant promise for applications in multifunctional sensors,switching devices,and information storage.However,the ...Organic-inorganic metal halides(OIMHs)possessing switchable optical and electrical properties hold significant promise for applications in multifunctional sensors,switching devices,and information storage.However,the challenge lies in achieving effective regulation of optical/electric responses through structural design strategies,and materials with structural phase transition coupling photoluminescence(PL)quenching are also relatively rare.Here,by employing halogen engineering to modify the parent compound(TEMA)PbBr_(3)(TEMA=triethylmethylammonium),we successfully obtained two derivatives(TECA)PbBr_(3) and(TEBA)PbBr_(3)(TECA=triethylchloromethylammonium and TEBA=triethylbromomethylammonium).Halogen engineering successfully introduces halogen-halogen interactions between PbBr_(3) n-inorganic frameworks and organic cations,which increases the stretching distortion of the PbBr_(6) octahedral framework of(TECA)PbBr_(3) and(TEBA)PbBr_(3),accompanied by prominent orange-red broadband emission behavior in(TECA)PbBr_(3) and(TEBA)PbBr_(3).Meanwhile,the phase transition temperatures(Tp)of(TECA)PbBr_(3) and(TEBA)PbBr_(3) have also been significantly increased compared to(TEMA)PbBr_(3),and two derivatives demonstrated switchable dielectric responses.Impressively,the reversible structural phase transition of(TECA)PbBr_(3) and(TEBA)PbBr_(3) dominates the outright PL quenching behavior,while still maintaining high PL emission intensity below the Tp.This represents a rare and extraordinary phenomenon in the realm of bistable responsive materials.This work provides a feasible strategy for designing and modulating photoluminescent phase transition materials and deepens understanding of the structural-performance relationship.展开更多
Convertible hydrogel supercapacitors have emerged as promising energy storage devices in switches,diodes,and transistors.However,inherent weaknesses in ionic conductivity,mechanical properties,and water retention of h...Convertible hydrogel supercapacitors have emerged as promising energy storage devices in switches,diodes,and transistors.However,inherent weaknesses in ionic conductivity,mechanical properties,and water retention of hydrogel electrolytes seriously hinder their development.Inspired by the hardness conversion of sea cucumber skin,a conductivity and mechanics dual-tunable salt gel electrolyte is successfully designed.The salt gel presents a reversible switching of conductors-insulators and a mechanical regulation between softness and hardness via the dissolution-crystallization transition of sodium acetate trihydrate(SAT).Meanwhile,the salt gels spontaneously grow a layer of“armor”through saturated phase-change salt crystals effectively reducing water evaporation of hydrogel electrolytes.Furthermore,this phase-change soft-rigid conversion strategy will expand the capabilities of gel-based flexible supercapacitors(area capacitance:258.6 mF cm^(-2)),and the capacitance retention rate could still reach 86.9%after 3000 cycles at high temperatures.Moreover,the salt gel supercapacitor is potentially used in over-heat alarm systems.It is anticipated that the strategy of conductivity and mechanics of dual-tunable salt gel would provide a new perspective on the development of energy storage devices,wearable electronics,and flexible robots.展开更多
Fe-Mn based layer oxides cathode materials have attracted widespread attention as a potential candidate for sodium-ion batteries(SIBs)owing to the earth abundance,cost-effectiveness and acceptable specific capacity.Ho...Fe-Mn based layer oxides cathode materials have attracted widespread attention as a potential candidate for sodium-ion batteries(SIBs)owing to the earth abundance,cost-effectiveness and acceptable specific capacity.However,the irreversible phase transition often brings rapid capacity decay,which seriously hinders the practical application in large-scale energy storage.Herein,we design a nickel-doped Na_(0.70)Fe_(0.10)Cu_(0.20)Ni_(0.05)Mn_(0.65)O_(2)(NFCNM-0.05)cathode material of SIBs with activated anionic redox reaction,and then inhibit the harmful phase transition.The ex-situ X-ray diffraction patterns demonstrate the NFCNM-0.05 always keeps the P2 phase during the sodiation/desodiation process,indicating a high structure stability.The ex-situ X-ray photoelectron spectroscopy implies the redox reactions between O2-and O-occur in the charging process,which offers extra specific capacity.Thus,the NFCNM-0.05 electrode delivers a high initial discharge capacity of 148 mA h g-1and remains a prominent cycling stability with an excellent capacity retention of 95.9%after 200 cycles at 1 C.In addition,the electrochemical impedance spectroscopy and galvanostatic intermittent titration technique show the NFCNM-0.05 electrode possesses fast ion diffusion ability,which is beneficial for the enhancement of rate performance.Even at 10 C,the NFCNM-0.05 can offer a reversible discharge capacity of 81 mA h g-1.DFT calculation demonstrates the doping of appropriate amount of Ni ions is benefit for the enhancement of the electrochemical performance of the layer oxides.This work provides an effective strategy to enhance the electrochemical performance of Fe-Mn based cathode materials of SIBs.展开更多
Deep eutectic solvents(DESs)have drawn considerable attention as a new type of green solvent since they were reported.Subsequent studies have shown that DESs have the potential to be used as“designable”solvents,whic...Deep eutectic solvents(DESs)have drawn considerable attention as a new type of green solvent since they were reported.Subsequent studies have shown that DESs have the potential to be used as“designable”solvents,which means that the precursors of DESs with different structures and properties can be screened to customize DESs for specific functions.Researchers have found that during the sample preparation process involving DESs,the specific properties of some“smart”DESs can be switched by directing external driving forces,leading to a reversible phase transition of the target solution.These"smart"DESs are called switchable deep eutectic solvents(SDESs).The advent of SDES simplifies the sample pretreatment steps,reduces the use of organic solvents,and makes solvents easy to recycle,which matches the concept of green and sustainable chemistry.Compared with the number of previous experimental studies,the reviews and summaries on SDESs are rare.Therefore,this review made a summary of the concept and research progress of SDESs based on some related works in the past decade,including composition and type,characterization,switching mechanism,etc.It is expected to provide a certain reference and guidance for the subsequent in-depth research of SDESs in the analytical sample pretreatment.展开更多
O3-type layered metal oxides have excellent prospects for cathode materials in Na-ion batteries(NIBs)on account of their advantages,such as low cost.The layered oxide cathodes are now promising for commercial utilizat...O3-type layered metal oxides have excellent prospects for cathode materials in Na-ion batteries(NIBs)on account of their advantages,such as low cost.The layered oxide cathodes are now promising for commercial utilization.Nevertheless,the serious and irreversible phase transformation at high voltages,along with the slow kinetics of Na^(+) ion diffusion,presents considerable obstacles to the attainment of highperformance layered cathodes.In this work,we develop a novel layered cathode,O3-NaNi_(0.25)Fe_(0.2)Mn_(0.3)(LiCuAlTiSn)_(0.05)O_(2)(HEONFM),based on the tiny high-entropy substitution strategy.The material with tiny high entropy substitution is proven to maintain the original crystal structures.The phase transition properties between P3 and O3 were improved,and the ordered arrangement of Na vacancies was significantly reduced.The structural entropy is greatly increased by introducing multiple elements into NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(NFM)transition metal layers,hence enhancing structural stability in the electrochemical reactions.HEO-NFM shows outstanding rate capability(106 mAh·g^(−1) at 10 C)along with ultra-high cycling stability(70%capacity retention after 500 cycles).The full battery provides a capacity of 97 mAh·g^(−1) at 5 C and maintains 81.4%capacity retention after 200 cycles,indicating great potential for applications.Herein,the tiny high-entropy substitution strategy inspires more rational designs of cathode materials with superior performances.展开更多
Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses a...Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized.In this work,a large strain response of 0.61%is achieved in lead-free(0.94-x%)(Bi_(0.5)Na_(0.5))TiO_(3)-0.06BaTiO_(3)-x%NaNbO_(3)(x=0 e6,BNT-6BT-xNN)ceramics with the composition of x=3.5 in a pseudo-cubic structure.Coexistence of ferroelectric(FE)and relaxor(RE)domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor(ER)and non-ergodic(NR)states thanks to the substitution of antiferroelectric NN.BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature(RT)and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state.This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.展开更多
Two-dimensional(2D)materials with reversible phase transformation are appealing for their rich physics and potential applications in information storage.However,up to now,reversible phase transitions in 2D materials t...Two-dimensional(2D)materials with reversible phase transformation are appealing for their rich physics and potential applications in information storage.However,up to now,reversible phase transitions in 2D materials that can be driven by facile nondestructive methods,such as temperature,are still rare.Here,we introduce ultrathin Cu_(9)S_(5)crystals grown by chemical vapor deposition(CVD)as an exemplary case.For the first time,their basic electrical properties were investigated based on Hall measurements,showing a record high hole carrier density of~1022 cm^(-3) among 2D semiconductors.Besides,an unusual and repeatable conductivity switching behavior at~250 K were readily observed in a wide thickness range of CVD-grown Cu_(9)S_(5)(down to 2 unit-cells).Confirmed by in-situ selected area electron diffraction,this unusual behavior can be ascribed to the reversible structural phase transition between the room-temperature hexagonalβphase and low-temperatureβ’phase with a superstructure.Our work provides new insights to understand the physical properties of ultrathin Cu_(9)S_(5)crystals,and brings new blood to the 2D materials family with reversible phase transitions.展开更多
Host–vip inclusion compounds with multistage reversible phase transitions are ideal materials for constructing molecular ferroelectrics.However,how to accurately design a molecular ferroelectric from a non-ferroele...Host–vip inclusion compounds with multistage reversible phase transitions are ideal materials for constructing molecular ferroelectrics.However,how to accurately design a molecular ferroelectric from a non-ferroelectric phase transition to a ferroelectric phase transition is still a huge challenge.展开更多
A new organic–inorganic hybrid compound[(CH_(3))_(3)PCH_(2)OH][Cd(SCN)_(3)](1)has been synthesized,which exhibits a reversible phase transition at 248.5 K confirmed by differential scanning calorimetry.The phase tran...A new organic–inorganic hybrid compound[(CH_(3))_(3)PCH_(2)OH][Cd(SCN)_(3)](1)has been synthesized,which exhibits a reversible phase transition at 248.5 K confirmed by differential scanning calorimetry.The phase transition in 1 is from a centrosymmetric space group Pmcn to a non-centrosymmetric space group P2_(1),so that 1 exhibits a switchable second harmonic generation(SHG)effect between SHG-on and SHG-off states.This phase transition also displays switchable dielectric behaviors between high and low dielectric states accompanied by the remarkable dielectric relaxation described by the Cole–Cole equation.展开更多
Considering the nonminimal coupling of the dilaton field to the massive graviton field in Maxwelldilaton-massive gravity,we obtain a class of analytical solutions of charged black holes,which are neither asymptoticall...Considering the nonminimal coupling of the dilaton field to the massive graviton field in Maxwelldilaton-massive gravity,we obtain a class of analytical solutions of charged black holes,which are neither asymptotically flat nor(A)dS.The calculated thermodynamic quantities,such as mass,temperature,and entropy,verify the validity of the first law of black hole thermodynamics.Moreover,we further investigate the critical behaviors of these black holes in the grand canonical and canonical ensembles and find a novel critical phenomenon never before observed,known as the"reverse"reentrant phase transition with a tricritical point.It implies that the system undergoes a novel"SBH-LBH-SBH"phase transition process and is the reverse of the"LBH-SBH-LBH"process observed in reentrant phase transitions.展开更多
基金supported by the National Natural Science Foundation of China(No.52377212 and 51877173)program of Beijing Huairou Laboratory(ZD2022006A)+2 种基金the Key R&D Project of Shaanxi Province(2023-YBGY-057)the State Key Laboratory of Electrical Insulation and Power Equipment(EIPE22314,EIPE22306)the Natural Science Basic Research Program of Shaanxi(No.2023-JC-QN-0483).
文摘Reversible solid oxide cells(RSOCs)are capable of converting various energy resources,between electricity and chemical fuels,with high efficiency and flexibility,making them suitable for grid balancing and renewable energy consumption.However,the practical application of RSOCs is still limited by the insufficient activity and stability of the electrodes in different operating modes.Herein,a highly efficient symmetrical electrode composed of La_(0.3)Sr_(0.6)Ti_(0.1)Co_(0.2)Fe_(0.7)O_(3-δ)(LSTCF)nanofibers and in situ exsolved Co_(3)Fe_(7) nanoparticles is developed for boosting the performance of RSOCs.The reversible phase transition,high activity and stability of the electrode have been confirmed by a combination of experimental(e.g.,transmission electron microscopy and X-ray absorption fine structure)and computational studies.Electrolyte-supported RSOCs with the symmetrical electrode demonstrate excellent catalytic activity and stability,achieving a high peak power density of 0.98 W cm^(-2)in the fuel cell mode using H_(2)as the fuel(or 0.53 W cm^(-2)using CH_(4)as the fuel)and a high current density of 1.09 A cm^(-2) at 1.4 V in the CO_(2)electrolysis mode(or 1.03 A cm^(-2)at 1.3 V for H_(2)O electrolysis)at 800℃while maintaining excellent durability for over 100 h.
基金supported by the National Natural Science Foundation of China(Grant No.21501194,51425206,91622107)National Basic Research Program of China(Grant No.2014CB648400)+2 种基金the National Key Research Project(Grant No.2016YFB1102302,2016YFB0402104)Xinjiang Key Research and Development Program(Grant No.2016B02021)Major Program of Xinjiang Uygur Autonomous Region of China during the 13th Five-Year Plan Period(Grant No.2016A02003).
文摘A new lithium zincoborate Li_(6)Zn_(3)(BO_(3))_(4) has been successfully prepared via a high-temperature solution method.Li_(6)Zn_(3)(BO_(3))_(4) is composed of LiO4 and ZnO_(4) tetrahedra,and nearly coplanar BO3 units.A facesharing LiO_(4) configuration was found in the title compound,and a comparison of Li-O configurations was systemically investigated for all Li-containing borates.Interestingly,Li_(6)Zn_(3)(BO_(3))_(4) has two reversible phase transitions at about 341 and 706℃,which implies that Li_(6)Zn_(3)(BO_(3))_(4) is a potential candidate as a phase change material.In situ high-temperature X-ray diffraction(XRD)and differential scanning calorimetry(DSC)analysis were used to verify the two reversible phase transitions.The linear optical properties were researched in detail using ab initio density functional theory(DFT).
基金The financial is supported by the National Natural Science Foundation of China (Nos. 22075132, 51802149, and U1801251)the Fundamental Research Funds for the Central Universities, and Nanjing University Technology Innovation Fund Project. The authors are also grateful to the High Performance Computing Center (HPCC) of Nanjing University for doing the numerical calculations in this paper on its blade cluster system. W. K. P. is grateful to the financial support by the Australian Research Council through a Future Fellowship project (No. FT160100251)The operational support of ANSTO staffs, especially Dr. Vanessa Peterson and Dr. Christophe Didier, on the collection of neutron powder diffraction data of NaNCMT is highly appreciated. The neutron diffraction data were collected at ANSTO (Australia), CSNS (China), and NIST (USA).
文摘Phase transition is common during (de)-intercalating layered sodium oxides, which directly affects the structural stability and electrochemical performance. However, the artificial control of phase transition to achieve advanced sodium-ion batteries is lacking, since the remarkably little is known about the influencing factor relative to the sliding process of transition-metal slabs upon sodium release and uptake of layered oxides. Herein, we for the first time demonstrate the manipulation of oxygen vacancy concentrations in multinary metallic oxides has a significant impact on the reversibility of phase transition, thereby determining the sodium storage performance of cathode materials. Results show that abundant oxygen vacancies intrigue the return of the already slide transition-metal slabs between O_(3) and P_(3) phase transition, in contrast to the few oxygen vacancies and resulted irreversibility. Additionally, the abundant oxygen vacancies enhance the electronic and ionic conductivity of the Na0.9Ni0.3Co0.15Mn0.05Ti0.5O2 electrode, delivering the high initial Coulombic efficiency of 97.1%, large reversible capacity of 112.7 mAh·g−1, superior rate capability upon 100 C and splendid cycling performance over 1,000 cycles. Our findings open up new horizons for artificially manipulating the structural evolution and electrochemical process of layered cathodes, and pave a way in designing advanced sodium-ion batteries.
基金supported by the National Natural Science Foundation of China(Grant No.21975062 and 52072109)the Natural Science Foundation of Hebei Province(E2023201017 and B2023201108)+2 种基金the Key Laboratory of Chemical Biology of Hebei Province(22567635H)the Excellent Youth Research Innovation Team of Hebei University(QNTD202403)the Post-graduate’s Innovation Fund Project of Hebei Province(CXZZSS2024004).
文摘Manipulating light polarization in birefringent crystals is central to photonic applications.However,controlling intrinsic optical anisotropy in a noninvasive manner remains challenging.Here,we report our discovery of the polymorphism of the inorganic birefringent crystal KCe(SO_(4))_(2).P and P2_(1/c)-KCe(SO_(4))_(2) crystals can be obtained through polymorph-controllable synthesis.Interestingly,P-KCe(SO_(4))_(2) exhibits reversible phase transition during which the birefringence value varies by up to 50%.The material is highly stable and the birefringence alteration stimulated by thermally induced phase transition is reversible for over 10 cycles,demonstrating its potential as a birefringence switch.We reveal that the optical anisotropy of KCe(SO_(4))_(2) polymorphs primarily stems from the arrangement of [CeO_(9)] and [KO_(10)] structural units,as evidenced by the dipole moments and first principles calculations.Our work not only provides new insights into the controlled synthesis of polymorphic materials but also advances the development of tunable birefringent materials for integrated photonics.
基金supported by the National Natural Science Foundation of China(21771037 and 21805033).
文摘A one-dimensional coordination polymer[(C_(2)H_(4)OH)C_(4)H_(9)NS]CdCl_(3)(1)with flexible N-(2-hydroxyethyl)thiomorpholinium cations coordinating to central metal Cd crystallized in a chiral space group P2_(1)2_(1)2_(1)and showed a reversible phase transition at 174.4/162.8 K,which corresponded to the second harmonic generation(SHG)activity and dielectric switching.The introduction of a thioether group enables 1 to adsorb Pd(II)metal ions and the SHG signal and dielectric switching disappeared after adsorption;hence,Pd(II)adsorption can be monitored by the measurements of SHG and dielectric switching.This study emphasizes the advantages of introducing functional groups into the phase transition materials and presents a new approach to design multifunctional materials.
基金supported by the National Natural Science Foundation of China(Grant No.21991141 and 22371258)。
文摘Organic-inorganic metal halides(OIMHs)possessing switchable optical and electrical properties hold significant promise for applications in multifunctional sensors,switching devices,and information storage.However,the challenge lies in achieving effective regulation of optical/electric responses through structural design strategies,and materials with structural phase transition coupling photoluminescence(PL)quenching are also relatively rare.Here,by employing halogen engineering to modify the parent compound(TEMA)PbBr_(3)(TEMA=triethylmethylammonium),we successfully obtained two derivatives(TECA)PbBr_(3) and(TEBA)PbBr_(3)(TECA=triethylchloromethylammonium and TEBA=triethylbromomethylammonium).Halogen engineering successfully introduces halogen-halogen interactions between PbBr_(3) n-inorganic frameworks and organic cations,which increases the stretching distortion of the PbBr_(6) octahedral framework of(TECA)PbBr_(3) and(TEBA)PbBr_(3),accompanied by prominent orange-red broadband emission behavior in(TECA)PbBr_(3) and(TEBA)PbBr_(3).Meanwhile,the phase transition temperatures(Tp)of(TECA)PbBr_(3) and(TEBA)PbBr_(3) have also been significantly increased compared to(TEMA)PbBr_(3),and two derivatives demonstrated switchable dielectric responses.Impressively,the reversible structural phase transition of(TECA)PbBr_(3) and(TEBA)PbBr_(3) dominates the outright PL quenching behavior,while still maintaining high PL emission intensity below the Tp.This represents a rare and extraordinary phenomenon in the realm of bistable responsive materials.This work provides a feasible strategy for designing and modulating photoluminescent phase transition materials and deepens understanding of the structural-performance relationship.
基金National Natural Science Foundation of China(No.52303144)Department of Science and Technology of Jilin Province(Nos YDZJ202301ZYTS295 and 20230508188RC)。
文摘Convertible hydrogel supercapacitors have emerged as promising energy storage devices in switches,diodes,and transistors.However,inherent weaknesses in ionic conductivity,mechanical properties,and water retention of hydrogel electrolytes seriously hinder their development.Inspired by the hardness conversion of sea cucumber skin,a conductivity and mechanics dual-tunable salt gel electrolyte is successfully designed.The salt gel presents a reversible switching of conductors-insulators and a mechanical regulation between softness and hardness via the dissolution-crystallization transition of sodium acetate trihydrate(SAT).Meanwhile,the salt gels spontaneously grow a layer of“armor”through saturated phase-change salt crystals effectively reducing water evaporation of hydrogel electrolytes.Furthermore,this phase-change soft-rigid conversion strategy will expand the capabilities of gel-based flexible supercapacitors(area capacitance:258.6 mF cm^(-2)),and the capacitance retention rate could still reach 86.9%after 3000 cycles at high temperatures.Moreover,the salt gel supercapacitor is potentially used in over-heat alarm systems.It is anticipated that the strategy of conductivity and mechanics of dual-tunable salt gel would provide a new perspective on the development of energy storage devices,wearable electronics,and flexible robots.
基金supported by the National Natural Science Foundation of China(U1960107)the Natural Science Foundation of Hebei Province(E2022501014)+3 种基金the “333”Talent Project of Hebei Province(A202005018)the Fundamental Research Funds for the Central Universities(N2123034)the Science and Technology Research Youth Fund Project of Higher Education Institutions of Hebei Province(QN2022196)the Performance subsidy fund for Key Laboratory of Dielectric and Electrolyte Functional Material Hebei Province(22567627H)。
文摘Fe-Mn based layer oxides cathode materials have attracted widespread attention as a potential candidate for sodium-ion batteries(SIBs)owing to the earth abundance,cost-effectiveness and acceptable specific capacity.However,the irreversible phase transition often brings rapid capacity decay,which seriously hinders the practical application in large-scale energy storage.Herein,we design a nickel-doped Na_(0.70)Fe_(0.10)Cu_(0.20)Ni_(0.05)Mn_(0.65)O_(2)(NFCNM-0.05)cathode material of SIBs with activated anionic redox reaction,and then inhibit the harmful phase transition.The ex-situ X-ray diffraction patterns demonstrate the NFCNM-0.05 always keeps the P2 phase during the sodiation/desodiation process,indicating a high structure stability.The ex-situ X-ray photoelectron spectroscopy implies the redox reactions between O2-and O-occur in the charging process,which offers extra specific capacity.Thus,the NFCNM-0.05 electrode delivers a high initial discharge capacity of 148 mA h g-1and remains a prominent cycling stability with an excellent capacity retention of 95.9%after 200 cycles at 1 C.In addition,the electrochemical impedance spectroscopy and galvanostatic intermittent titration technique show the NFCNM-0.05 electrode possesses fast ion diffusion ability,which is beneficial for the enhancement of rate performance.Even at 10 C,the NFCNM-0.05 can offer a reversible discharge capacity of 81 mA h g-1.DFT calculation demonstrates the doping of appropriate amount of Ni ions is benefit for the enhancement of the electrochemical performance of the layer oxides.This work provides an effective strategy to enhance the electrochemical performance of Fe-Mn based cathode materials of SIBs.
基金financially supported by the National Natural Science Foundation of China(No.22174129)the Natural Science Foundation of Zhejiang Province(No.LZY21E030001)。
文摘Deep eutectic solvents(DESs)have drawn considerable attention as a new type of green solvent since they were reported.Subsequent studies have shown that DESs have the potential to be used as“designable”solvents,which means that the precursors of DESs with different structures and properties can be screened to customize DESs for specific functions.Researchers have found that during the sample preparation process involving DESs,the specific properties of some“smart”DESs can be switched by directing external driving forces,leading to a reversible phase transition of the target solution.These"smart"DESs are called switchable deep eutectic solvents(SDESs).The advent of SDES simplifies the sample pretreatment steps,reduces the use of organic solvents,and makes solvents easy to recycle,which matches the concept of green and sustainable chemistry.Compared with the number of previous experimental studies,the reviews and summaries on SDESs are rare.Therefore,this review made a summary of the concept and research progress of SDESs based on some related works in the past decade,including composition and type,characterization,switching mechanism,etc.It is expected to provide a certain reference and guidance for the subsequent in-depth research of SDESs in the analytical sample pretreatment.
基金the financial support from Tianjin Univerity of Technology.
文摘O3-type layered metal oxides have excellent prospects for cathode materials in Na-ion batteries(NIBs)on account of their advantages,such as low cost.The layered oxide cathodes are now promising for commercial utilization.Nevertheless,the serious and irreversible phase transformation at high voltages,along with the slow kinetics of Na^(+) ion diffusion,presents considerable obstacles to the attainment of highperformance layered cathodes.In this work,we develop a novel layered cathode,O3-NaNi_(0.25)Fe_(0.2)Mn_(0.3)(LiCuAlTiSn)_(0.05)O_(2)(HEONFM),based on the tiny high-entropy substitution strategy.The material with tiny high entropy substitution is proven to maintain the original crystal structures.The phase transition properties between P3 and O3 were improved,and the ordered arrangement of Na vacancies was significantly reduced.The structural entropy is greatly increased by introducing multiple elements into NaNi_(1/3)Fe_(1/3)Mn_(1/3)O_(2)(NFM)transition metal layers,hence enhancing structural stability in the electrochemical reactions.HEO-NFM shows outstanding rate capability(106 mAh·g^(−1) at 10 C)along with ultra-high cycling stability(70%capacity retention after 500 cycles).The full battery provides a capacity of 97 mAh·g^(−1) at 5 C and maintains 81.4%capacity retention after 200 cycles,indicating great potential for applications.Herein,the tiny high-entropy substitution strategy inspires more rational designs of cathode materials with superior performances.
基金supported by the Natural Science Foundation of China(Grant No.51902246,12161141012,and 12174299)the China National Key R&D Program(Grant No.2021YFB3201800 and 2020YFC0122100)+5 种基金the Natural Science Fundamental Research Project of Shaanxi Province of China(No.2019JQ590)the Key R&D Program of Shaanxi Province of China(2020GY-271)the Fundamental Research Funds for the Central Universities(xzd012020059)the“111 Project”of China(B14040)the Natural Sciences&Engineering Research Council of Canada(NSERC,Discovery Grant No.RGPIN-2017-06915)Xijiang Innovation Team Introduction Program of Zhaoqing(Jiecheng).
文摘Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized.In this work,a large strain response of 0.61%is achieved in lead-free(0.94-x%)(Bi_(0.5)Na_(0.5))TiO_(3)-0.06BaTiO_(3)-x%NaNbO_(3)(x=0 e6,BNT-6BT-xNN)ceramics with the composition of x=3.5 in a pseudo-cubic structure.Coexistence of ferroelectric(FE)and relaxor(RE)domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor(ER)and non-ergodic(NR)states thanks to the substitution of antiferroelectric NN.BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature(RT)and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state.This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.
基金J.X.W.acknowledges financial support from the National Natural Science Foundation of China(NSFC)(No.92064005)Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure(No.SKL202211SIC)+6 种基金H.T.Y.acknowledges the support from the NSFC(Nos.51861145201,52072168,and 21733001)the National Key Research and Development Program of China(No.2018YFA0306200)J.W.H.acknowledges the support from the National Key Research and Development Program of China(No.2021YFA1202901)X.W.F.acknowledges financial support from the NSFC at grant(Nos.11974191 and 2217830)the National Key Research and Development Program of China at grant(No.2020YFA0309300)the Natural Science Foundation of Tianjin at grant(Nos.20JCZDJC00560 and 20JCJQJC00210)the 111 Project(No.B23045).
文摘Two-dimensional(2D)materials with reversible phase transformation are appealing for their rich physics and potential applications in information storage.However,up to now,reversible phase transitions in 2D materials that can be driven by facile nondestructive methods,such as temperature,are still rare.Here,we introduce ultrathin Cu_(9)S_(5)crystals grown by chemical vapor deposition(CVD)as an exemplary case.For the first time,their basic electrical properties were investigated based on Hall measurements,showing a record high hole carrier density of~1022 cm^(-3) among 2D semiconductors.Besides,an unusual and repeatable conductivity switching behavior at~250 K were readily observed in a wide thickness range of CVD-grown Cu_(9)S_(5)(down to 2 unit-cells).Confirmed by in-situ selected area electron diffraction,this unusual behavior can be ascribed to the reversible structural phase transition between the room-temperature hexagonalβphase and low-temperatureβ’phase with a superstructure.Our work provides new insights to understand the physical properties of ultrathin Cu_(9)S_(5)crystals,and brings new blood to the 2D materials family with reversible phase transitions.
基金supported by the National Nature Science Foundation of China(Grant No.21761013,21671086,21461010 and 21471070)the Science and Technology Bureau Project of Ganzhou.
文摘Host–vip inclusion compounds with multistage reversible phase transitions are ideal materials for constructing molecular ferroelectrics.However,how to accurately design a molecular ferroelectric from a non-ferroelectric phase transition to a ferroelectric phase transition is still a huge challenge.
基金financially supported by the National Natural Science Foundation of China(no.21471032)the Project 973(2014CB848800)and the Fundamental Research Funds for the Central Universities for Ye Qiong.
文摘A new organic–inorganic hybrid compound[(CH_(3))_(3)PCH_(2)OH][Cd(SCN)_(3)](1)has been synthesized,which exhibits a reversible phase transition at 248.5 K confirmed by differential scanning calorimetry.The phase transition in 1 is from a centrosymmetric space group Pmcn to a non-centrosymmetric space group P2_(1),so that 1 exhibits a switchable second harmonic generation(SHG)effect between SHG-on and SHG-off states.This phase transition also displays switchable dielectric behaviors between high and low dielectric states accompanied by the remarkable dielectric relaxation described by the Cole–Cole equation.
基金Supported by the National Key Research and Development Program of China(2020YFC2201400)supported by the National Natural Science Foundation of China(12365009)the Natural Science Foundation of Jiangxi Province,China(20232BAB201039)。
文摘Considering the nonminimal coupling of the dilaton field to the massive graviton field in Maxwelldilaton-massive gravity,we obtain a class of analytical solutions of charged black holes,which are neither asymptotically flat nor(A)dS.The calculated thermodynamic quantities,such as mass,temperature,and entropy,verify the validity of the first law of black hole thermodynamics.Moreover,we further investigate the critical behaviors of these black holes in the grand canonical and canonical ensembles and find a novel critical phenomenon never before observed,known as the"reverse"reentrant phase transition with a tricritical point.It implies that the system undergoes a novel"SBH-LBH-SBH"phase transition process and is the reverse of the"LBH-SBH-LBH"process observed in reentrant phase transitions.
