Rational design of diamond through microstructure engineering:From synthesis to applications

Diamond possesses excellent thermal conductivity and tunable bandgap.Currently,the high-pressure,high-temperature,and chemical vapor deposition methods are the most promising strategies for the commercial-scale production of synthetic diamond.Although diamond has been extensively employed in jewelry and cutting/grinding tasks,the realization of its high-end applications through microstructure engineering has long been sought.Herein,we discuss the microstructures encountered in diamond and further concentrate on cutting-edge investigations utilizing electron microscopy techniques to illuminate the transition mechanism between graphite and diamond during the synthesis and device constructions.The impacts of distinct microstructures on the electrical applications of diamond,especially the photoelectrical,electrical,and thermal properties,are elaborated.The recently reported elastic and plastic deformations revealed through in situ microscopy techniques are also summarized.Finally,the limitations,perspectives,and corresponding solutions are proposed.

Realization of an Adaptive Radiative Cooler with a Multilayer-Filter VO_(2)-Based Fabry-Pérot Cavity

A high-performance adaptive radiative cooler comprising a multilayer-filter VO_(2)-based Fabry-Pérot(FP)cavity is proposed.The bottom FP cavity has four layers,VO_(2)/NaCl/PVC/Ag.Based on the phase transition of VO_(2),the average emissivity in the transparent window can be switched from 3.7%to 96.3%.Additionally,the average emissivity can also be adjusted with external strain to the PVC layer,providing another way to attain the desired cooling effect.An upper filter is included to block most of the solar radiation and provide a transmittance of 96.7% in the atmospheric window.At high temperature,the adaptive emitter automatically activates radiative cooling.The net cooling power is up to 156.4 W·m^(-2)at an ambient temperature of 303 K.Our adaptive emitter still exhibits stable selective emissivity at different incident angles and heat transfer coefficients.At low temperature,the radiative cooling automatically deactivates,and the average emissivity decreases to only 3.8%.Therefore,our work not only provides new insights into the design of high-performance adaptive radiative coolers but also advances the development of intelligent thermal management.

Strong electron correlation-induced Mott-insulating electrides of Ae_(5)X_(3)(Ae=Ca,Sr,and Ba;X=As and Sb)

The presence of interstitial electrons in electrides endows them with interesting attributes,such as low work function,high carrier concentration,and unique magnetic properties.Thorough knowledge and understanding of electrides are thus of both scientific and technological significance.Here,we employ first-principles calculations to investigate Mott-insulating Ae_(5)X_(3)(Ae=Ca,Sr,and Ba;X=As and Sb)electrides with Mn_(5)Si_(3)-type structure,in which half-filled interstitial electrons serve as ions and are spin-polarized.The Mott-insulating property is induced by strong electron correlation between the nearest interstitial electrons,resulting in spin splitting and a separation between occupied and unoccupied states.The half-filled antiferromagnetic configuration and localization of the interstitial electrons are critical for the Mott-insulating properties of these materials.Compared with that in intermetallic electrides,the orbital hybridization between the half-filled interstitial electrons and the surrounding atoms is weak,leading to highly localized magnetic centers and pronounced correlation effects.Therefore,the Mott-insulating electrides Ae_(5)X_(3)have very large indirect bandgaps(0.30 eV).In addition,high pressure is found to strengthen the strong correlation effects and enlarge the bandgap.The present results provide a deeper understanding of the formation mechanism of Mott-insulating electrides and provide guidance for the search for new strongly correlated electrides.

Microwave-Assisted Confining Growth and Liquid Exfoliation of sp^(3)-Hybrid Carbon Nitride Nano/Micro-Crystals

As one promising carbon-based material,sp^(3)-hybrid carbon nitride has been predicted with various novel physicochemical properties.However,the synthesis of sp^(3)-hybrid carbon nitride is still limited by the nanaoscale,low crystallinity,complex source,and expensive instruments.Herein,we have presented a facile approach to the sp^(3)-hybrid carbon nitride nano/micro-crystals with microwave-assisted confining growth and liquid exfoliation.Actually,the carbon nitride nano/micro-crystals can spontaneously emerge and grow in the microwave-assisted polymerization of citric acid and urea,and the liquid exfoliation can break the bulk disorder polymer to retrieve the highly crystalline carbon nitride nano/micro-crystals.The obtained carbon nitride nano/micro-crystals present superior blue light absorption strength and surprising photoluminescence quantum yields of 57.96%in ethanol and 18.05%in solid state.The experimental characterizations and density functional theory calculations reveal that the interface-trapped localized exciton may contribute to the excellent intrinsic light emission capability of carbon nitride nano/micro-crystals and the interparticle staggered stacking will prevent the aggregation-caused-quenching partially.Finally,the carbon nitride nano/micro-crystals are demonstrated to be potentially useful as the phosphor medium in light-emitting-diode for interrupting blue light-induced eye damage.This work paves new light on the synthesis strategy of sp^(3)-hybrid carbon nitride materials and thus may push forward the development of multiple carbon nitride research.

Finely regulated luminescent Ag-In-Ga-S quantum dots with green-red dual emission toward white light-emitting diodes

Ag-In-Ga-S(AIGS)quantum dots(QDs)have recently attracted great interests due to the outstanding optical properties and eco-friendly components,which are considered as an alternative replacement for toxic Pb-and Cd-based QDs.However,enormous attention has been paid to how to narrow their broadband spectra,ignoring the application advantages of the broadband emission.In this work,the AIGS QDs with controllable broad green-red dual-emission are first reported,which is achieved through adjusting the size distribution of QDs by controlling the nucleation and growth of AIGS crystals.Resultantly,the AIGS QDs exhibit broad dual-emission at green-and red-band evidenced by photoluminescence(PL)spectra,and the PL relative intensity and peak position can be finely adjusted.Furthermore,the dual-emission is the intrinsic characteristics from the difference in confinement effect of large particles and tiny particles confirmed by temperature-dependent PL spectra.Accordingly,the AIGS QDs(the size consists of 17 nm and 3.7 nm)with 530 nm and 630 nm emission could successfully be synthesized at 220°C.By combining the blue light-emitting diode(LED)chips and dual-emission AIGS QDs,the constructed white light-emitting devices(WLEDs)exhibit a continuous and broad spectrum like natural sunlight with the Commission Internationale de l’Eclairage(CIE)chromaticity coordinates of(0.33,0.31),a correlated color temperature(CCT)of 5425 K,color rendering index(CRI)of 90,and luminous efficacy of radiation(LER)of 129 lm/W,which indicates that the AIGS QDs have huge potential for lighting applications.

声学三维量子霍尔态的观测

Quantum Hall effect,the quantized transport phenomenon of electrons under strong magnetic fields,remains one of the hottest research topics in condensed matter physics since its discovery in 2D electronic systems.Recently,as a great advance in the research of quantum Hall effects,the quantum Hall effect in 3D systems,despite its big challenge,has been achieved in the bulk ZrTe_(5)and Cd_(3)As_(2)materials.Interestingly,Cd_(3)As_(2)is a Weyl semimetal,and quantum Hall effect is hosted by the Fermi arc states on opposite surfaces via the Weyl nodes of the bulk,and induced by the unique edge states on the boundaries of the opposite surfaces.However,such intriguing edge state distribution has not yet been experimentally observed.Here,we aim to reveal experimentally the unusual edge states of Fermi arcs in acoustic Weyl system with the aid of pseudo-magnetic field.Benefiting from the macroscopic nature of acoustic crystals,the pseudo-magnetic field is introduced by elaborately designed the gradient onsite energy,and the edge states of Fermi arcs on the boundaries of the opposite surfaces are unambiguously demonstrated in experiments.Our system serves as an ideal and highly tunable platform to explore the Hall physics in 3D system,and has the potential in the application of new acoustic devices.

Oxygen vacancy promoting artificial atom(RuPd)by d-orbital coupling for efficient water dissociation

Rational design of highly active catalysts for breaking hydrogen-oxygen bonds is of great significance in energy chemical reactions involving water.Herein,an efficient strategy for the artificial atom(RuPd)established by d-orbital coupling and adjusted by oxygen vacancy(V_(O))is verified for water dissociation.As an experimental verification,the turnover frequency of RuPd-TiO_(2)-VO(RuPdTVO)catalyst in ammonia borane hydrolysis reaches up to 2750 min^(−1)(26,190 min−1 based on metal dispersion)in the absence of alkali,exceeding the highest active catalysts(Rh-based catalysts).The d-orbital coupling effect between Ru and Pd simulates the outer electronic structure of Rh.Electron transfer from V_(O) to(RuPd)constructs an electron-rich state of active sites that further enhances the ability of the artificial atom to dissociate water.This work provides an effective electronic regulation strategy from V_(O) and artificial atom constructed by d-orbital coupling effect for efficient water dissociation.