Oxygen carriers play a fundamental role in chemical looping combustion(CLC).Iron-based carriers have been extensively investigated owing to their abundance and environmentally friendly.However,the reactivity and separ...Oxygen carriers play a fundamental role in chemical looping combustion(CLC).Iron-based carriers have been extensively investigated owing to their abundance and environmentally friendly.However,the reactivity and separability of iron-based carriers require further enhancement.This study investigates the effect of the concentration of Mn doping on reactivity,elastic properties and magnetic properties based on density functional theory(DFT)calculations.Theoretical results demonstrate that Mn doping effectively enhances reactivity by reducing the oxygen vacancy formation energy(E_(vac))from 2.33 to 0.87 eV.However,Mn doping introduces HV/EV Ms lattice distortions that deteriorate elastic properties,thereby reducing wear resistance,as evidenced by a 54.54%decrease in the hardness-to-Young's modulus ratio(H_(v)/E_(v))forα-Fe_(2)O_(3)and an 83.33%reduction for Fe_(3)O_(4).Furthermore,Mn doping also modifies magnetic properties.The maximum of saturation magnetization(M_(s))of Fe_(3)O_(4)reaches 121.02 emu/g at 33.33%Mn doping concentration.Finally,systematic evaluation identifies 33.33%as the optimal Mn doping concentration,achieving a balance in enhanced reactivity,superior magnetic performance,and retained elastic stability.展开更多
采用高温固相法制备了SrZrSi_(2)O_(7):Ce^(3+),Mn^(2+)荧光粉。通过X射线衍射(X-ray Power Diffractometer,XRD)、激发和发射光谱及电子显微分析对材料的分子结构、显微形貌、发光特性和能量传递机理进行了研究。结果表明,荧光粉的主...采用高温固相法制备了SrZrSi_(2)O_(7):Ce^(3+),Mn^(2+)荧光粉。通过X射线衍射(X-ray Power Diffractometer,XRD)、激发和发射光谱及电子显微分析对材料的分子结构、显微形貌、发光特性和能量传递机理进行了研究。结果表明,荧光粉的主晶相是单斜晶系的SrZrSi_(2)O_(7),Ce^(3+)离子和Mn^(2+)离子占据一部分Sr^(2+)离子的晶体学格位。在296 nm激发下,可以观察到来自Ce^(3+)离子的蓝光发射峰,归属于Ce^(3+)离子的5d→4f能级跃迁。在544 nm处,有来自Mn^(2+)离子的绿光发射峰,归因于Mn^(2+)离子的^(4)T_(1)(4G)-^(6)A_(1)(6S)自旋禁止跃迁,表明发生了从Ce^(3+)离子到Mn^(2+)离子的能量传递过程,为设计蓝光到绿光之间可控制备的新型荧光粉提供了理论和实验的信息。展开更多
P2-type nickel-manganese-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs),but their application is limited by initial specific capacity and anion redox instability.Herein,a P2/O3 bip...P2-type nickel-manganese-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs),but their application is limited by initial specific capacity and anion redox instability.Herein,a P2/O3 biphasic Na_(0.67)Ni_(0.33)Mn_(0.6)Cu_(0.05)Mg_(0.07)Ti_(0.01)O_(2)(Ni33Mn60)was prepared by adjusting the Ni/Mn ratio with as Na_(0.67)Ni_(0.23)Mn_(0.65)Cu_(0.05)Mg_(0.07)Ti_(0.01)O_(2)(Ni23Mn65)matrix and is reported to exhibit high initial discharge capacity,cyclability and rate capability.The density functional theory(DFT)calculation and experimental data prove the enhancement of the Mn^(3+)/Mn^(4+)redox process to improve the specific discharge capacity and the P2/O3biphasic structure to optimize the anion kinetics.The synthesized oxide Ni33Mn60 delivers a high initial discharge specific capacity of 140.21 mAh g^(-1),a crucial discharge capacity of 76.07 mAh g^(-1)at 10C,a preferable capacity retention rate of 78.97%after 200 cycles at 5C and cycle stability at high voltages above 4.3V.In situ X-ray diffraction(XRD)and galvanostatic intermittent titration technique(GITT)tests show that Ni33Mn60 has reversible structure evolution and fast Na^(+)diffusion kinetics due to the ion effect and unique P2/O3 biphasic structure,respectively.This work provides a new thought about adjusting matrix ratio for the preparation of P2/O3 biphasic cathode materials for advanced SIBs.展开更多
基金Supported by National Natural Science Foundation of China(50976032,51776070)。
文摘Oxygen carriers play a fundamental role in chemical looping combustion(CLC).Iron-based carriers have been extensively investigated owing to their abundance and environmentally friendly.However,the reactivity and separability of iron-based carriers require further enhancement.This study investigates the effect of the concentration of Mn doping on reactivity,elastic properties and magnetic properties based on density functional theory(DFT)calculations.Theoretical results demonstrate that Mn doping effectively enhances reactivity by reducing the oxygen vacancy formation energy(E_(vac))from 2.33 to 0.87 eV.However,Mn doping introduces HV/EV Ms lattice distortions that deteriorate elastic properties,thereby reducing wear resistance,as evidenced by a 54.54%decrease in the hardness-to-Young's modulus ratio(H_(v)/E_(v))forα-Fe_(2)O_(3)and an 83.33%reduction for Fe_(3)O_(4).Furthermore,Mn doping also modifies magnetic properties.The maximum of saturation magnetization(M_(s))of Fe_(3)O_(4)reaches 121.02 emu/g at 33.33%Mn doping concentration.Finally,systematic evaluation identifies 33.33%as the optimal Mn doping concentration,achieving a balance in enhanced reactivity,superior magnetic performance,and retained elastic stability.
文摘采用高温固相法制备了SrZrSi_(2)O_(7):Ce^(3+),Mn^(2+)荧光粉。通过X射线衍射(X-ray Power Diffractometer,XRD)、激发和发射光谱及电子显微分析对材料的分子结构、显微形貌、发光特性和能量传递机理进行了研究。结果表明,荧光粉的主晶相是单斜晶系的SrZrSi_(2)O_(7),Ce^(3+)离子和Mn^(2+)离子占据一部分Sr^(2+)离子的晶体学格位。在296 nm激发下,可以观察到来自Ce^(3+)离子的蓝光发射峰,归属于Ce^(3+)离子的5d→4f能级跃迁。在544 nm处,有来自Mn^(2+)离子的绿光发射峰,归因于Mn^(2+)离子的^(4)T_(1)(4G)-^(6)A_(1)(6S)自旋禁止跃迁,表明发生了从Ce^(3+)离子到Mn^(2+)离子的能量传递过程,为设计蓝光到绿光之间可控制备的新型荧光粉提供了理论和实验的信息。
基金financially supported by the Natural Science Foundation of Jiangsu Province(No.BK20201049)China Postdoctoral Science Foundation(No,2022M711724)+2 种基金the Swedish Energy Agency(Nos.P2022-00055 and P2023-00603)STandUP for EnergyMAX IV Laboratory for time on Balder beamline(No.20240704)
文摘P2-type nickel-manganese-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs),but their application is limited by initial specific capacity and anion redox instability.Herein,a P2/O3 biphasic Na_(0.67)Ni_(0.33)Mn_(0.6)Cu_(0.05)Mg_(0.07)Ti_(0.01)O_(2)(Ni33Mn60)was prepared by adjusting the Ni/Mn ratio with as Na_(0.67)Ni_(0.23)Mn_(0.65)Cu_(0.05)Mg_(0.07)Ti_(0.01)O_(2)(Ni23Mn65)matrix and is reported to exhibit high initial discharge capacity,cyclability and rate capability.The density functional theory(DFT)calculation and experimental data prove the enhancement of the Mn^(3+)/Mn^(4+)redox process to improve the specific discharge capacity and the P2/O3biphasic structure to optimize the anion kinetics.The synthesized oxide Ni33Mn60 delivers a high initial discharge specific capacity of 140.21 mAh g^(-1),a crucial discharge capacity of 76.07 mAh g^(-1)at 10C,a preferable capacity retention rate of 78.97%after 200 cycles at 5C and cycle stability at high voltages above 4.3V.In situ X-ray diffraction(XRD)and galvanostatic intermittent titration technique(GITT)tests show that Ni33Mn60 has reversible structure evolution and fast Na^(+)diffusion kinetics due to the ion effect and unique P2/O3 biphasic structure,respectively.This work provides a new thought about adjusting matrix ratio for the preparation of P2/O3 biphasic cathode materials for advanced SIBs.
