The barocaloric effect is considered as one of the most promising refrigeration with the potential to replace traditional gas compression refrigeration.One of the main obstacles to the application of barocaloric mater...The barocaloric effect is considered as one of the most promising refrigeration with the potential to replace traditional gas compression refrigeration.One of the main obstacles to the application of barocaloric materials lies in the requirement for high driving pressures.In this paper,we report on the barocaloric effect of Pb_(3)(VO_(4))_(2),which exhibits a ferroelastic transition from a high-temperature trigonal structure to a low-temperature monoclinic structure at 357 K,accompanied by a substantial volume change.The entropy change induced by hydrostatic pressure can reach up 14 J·kg^(-1)·K^(-1)under a relatively low pressure of 80 MPa.This work is expected to expand the selection range of barocaloric materials.展开更多
Coexistence of ferromagnetism and ferroelasticity in a single material is an intriguing phenomenon,but has been rarely found.Here we studied both the ferromagnetism and ferroelasticity in a group of LaCoO3 films with ...Coexistence of ferromagnetism and ferroelasticity in a single material is an intriguing phenomenon,but has been rarely found.Here we studied both the ferromagnetism and ferroelasticity in a group of LaCoO3 films with systematically tuned atomic structures.We found that all films exhibit ferroelastic domains with four-fold symmetry and the larger domain size(higher elasticity)is always accompanied by stronger ferromagnetism.We performed synchrotron x-ray diffraction studies to investigate the backbone structure of the CoO6 octahedra,and found that both the ferromagnetism and the elasticity are simultaneously enhanced when the in-plane Co–O–Co bond angles are straightened.Therefore the study demonstrates the inextricable correlation between the ferromagnetism and ferroelasticity mediated through the octahedral backbone structure,which may open up new possibilities to develop multifunctional materials.展开更多
Hafnium zirconium oxides(HZO),which exhibit ferroelectric properties,are promising materials for nanoscale device fabrication due to their high complementary metal-oxide-semiconductor(CMOS) compatibility.In addition t...Hafnium zirconium oxides(HZO),which exhibit ferroelectric properties,are promising materials for nanoscale device fabrication due to their high complementary metal-oxide-semiconductor(CMOS) compatibility.In addition to piezoelectricity,ferroelectricity,and flexoelectricity,this study reports the observation of ferroelasticity using piezoelectric force microscopy(PFM) and scanning transmission electron microscopy(STEM).The dynamics of 90° ferroelastic domains in HZO thin films are investigated under the influence of an electric field.Switching of the retentive domains is observed through repeated wake-up measurements.This study presents a possibility of enhancing polarization in HZO thin films during wake-up processes.展开更多
The fascinating properties arising from the interaction between different ferroic states of two-dimensional(2D) materials have inspired tremendous research interest in the past few years.Under the first-principles cal...The fascinating properties arising from the interaction between different ferroic states of two-dimensional(2D) materials have inspired tremendous research interest in the past few years.Under the first-principles calculations,we predict the coexistence of antiferromagnetic and ferroelastic states in VOX(X=Cl,Br,I) monolayers.The results illustrate that the VOX monolayers exhibit indirect bandgap characteristics,i.e.,their gaps decrease with the halide elements changing from Cl to I.The ground states of all these VOX monolayers are antiferromagnetic(AFM) with the magnetic moments contributed by the V 3d electrons.Furthermore,the magnetic ground state changing from AFM to ferromagnetism(FM) can be realized by doping carriers.In addition,the moderate ferroelastic transition barrier and reversible switching signal ensure their high performances of nonvolatile memory devices.Our findings not only offer an ideal platform for investigating the multiferroic properties,but also provide candidate materials for potential applications in spintronics.展开更多
Raman scattering measurements of K_2 Sr（MoO_4）2 were performed in the temperature range of 25–750？C. The Raman spectrum of the low-temperature phase α-K_2 Sr（MoO_4）2 that was obtained by first-principle calcula...Raman scattering measurements of K_2 Sr（MoO_4）2 were performed in the temperature range of 25–750？C. The Raman spectrum of the low-temperature phase α-K_2 Sr（MoO_4）2 that was obtained by first-principle calculations indicated that the Raman bands in the wavenumber region of 250–500 cm-1 are related to Mo–O bending vibrations in MoO4 tetrahedra,while the Raman bands in the wavenumber region of 650–950 cm-1 are attributed to stretching vibrations of Mo–O bonds.The temperature-dependent Raman spectra reveal that K_2 Sr（MoO_4）2 exhibits two sets of modifications in the Raman spectra at ～ 150？C and ～ 475？C, attributed to structural phase transitions. The large change of the Raman spectra in the temperature range of 150？C to 475？C suggests structural instability of the medium-temperature phase β-K_2 Sr（MoO_4）2.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52301241 and 52271175)。
文摘The barocaloric effect is considered as one of the most promising refrigeration with the potential to replace traditional gas compression refrigeration.One of the main obstacles to the application of barocaloric materials lies in the requirement for high driving pressures.In this paper,we report on the barocaloric effect of Pb_(3)(VO_(4))_(2),which exhibits a ferroelastic transition from a high-temperature trigonal structure to a low-temperature monoclinic structure at 357 K,accompanied by a substantial volume change.The entropy change induced by hydrostatic pressure can reach up 14 J·kg^(-1)·K^(-1)under a relatively low pressure of 80 MPa.This work is expected to expand the selection range of barocaloric materials.
基金the National Natural Science Foun-dation of China(Grant Nos.52072244 and 12104305)the Science and Technology Commission of Shanghai Municipal-ity(Grant No.21JC1405000)the ShanghaiTech Startup Fund.This research used resources of the Advanced Photon Source,a U.S.Department of Energy(DOE)Office of Sci-ence User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357.
文摘Coexistence of ferromagnetism and ferroelasticity in a single material is an intriguing phenomenon,but has been rarely found.Here we studied both the ferromagnetism and ferroelasticity in a group of LaCoO3 films with systematically tuned atomic structures.We found that all films exhibit ferroelastic domains with four-fold symmetry and the larger domain size(higher elasticity)is always accompanied by stronger ferromagnetism.We performed synchrotron x-ray diffraction studies to investigate the backbone structure of the CoO6 octahedra,and found that both the ferromagnetism and the elasticity are simultaneously enhanced when the in-plane Co–O–Co bond angles are straightened.Therefore the study demonstrates the inextricable correlation between the ferromagnetism and ferroelasticity mediated through the octahedral backbone structure,which may open up new possibilities to develop multifunctional materials.
基金Project supported by the the National Key Research and Development Program of China (Grant No. 2022YFA1402902)the National Natural Science Foundation of China (Grant Nos. 12074119, 12204171, 12134003, and 12374145)+1 种基金the Chenguang Program Foundation of Shanghai Education Development Foundation and Shanghai Municipal Education Commission, ECNU (East China Normal University) Multifunctional Platform for Innovation (006)the Fundamental Research Funds for the Central Universities。
文摘Hafnium zirconium oxides(HZO),which exhibit ferroelectric properties,are promising materials for nanoscale device fabrication due to their high complementary metal-oxide-semiconductor(CMOS) compatibility.In addition to piezoelectricity,ferroelectricity,and flexoelectricity,this study reports the observation of ferroelasticity using piezoelectric force microscopy(PFM) and scanning transmission electron microscopy(STEM).The dynamics of 90° ferroelastic domains in HZO thin films are investigated under the influence of an electric field.Switching of the retentive domains is observed through repeated wake-up measurements.This study presents a possibility of enhancing polarization in HZO thin films during wake-up processes.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12104344 and 61674003)the Shandong Provincial Natural Science Foundation,China(Grant No.ZR2021QA096)+1 种基金the Science and Technology Development Program of Weifang High-tech Industrial Development Zone,China(Grant No.2020KJHM03)the Doctoral Research Start-up Foundation of Weifang University,China(Grant No.2021BS05)。
文摘The fascinating properties arising from the interaction between different ferroic states of two-dimensional(2D) materials have inspired tremendous research interest in the past few years.Under the first-principles calculations,we predict the coexistence of antiferromagnetic and ferroelastic states in VOX(X=Cl,Br,I) monolayers.The results illustrate that the VOX monolayers exhibit indirect bandgap characteristics,i.e.,their gaps decrease with the halide elements changing from Cl to I.The ground states of all these VOX monolayers are antiferromagnetic(AFM) with the magnetic moments contributed by the V 3d electrons.Furthermore,the magnetic ground state changing from AFM to ferromagnetism(FM) can be realized by doping carriers.In addition,the moderate ferroelastic transition barrier and reversible switching signal ensure their high performances of nonvolatile memory devices.Our findings not only offer an ideal platform for investigating the multiferroic properties,but also provide candidate materials for potential applications in spintronics.
基金Project supported by the Natural Science Foundation of Anhui Province,China(Grant Nos.KJ2018A0588 and KJ2017A625)
文摘Raman scattering measurements of K_2 Sr（MoO_4）2 were performed in the temperature range of 25–750？C. The Raman spectrum of the low-temperature phase α-K_2 Sr（MoO_4）2 that was obtained by first-principle calculations indicated that the Raman bands in the wavenumber region of 250–500 cm-1 are related to Mo–O bending vibrations in MoO4 tetrahedra,while the Raman bands in the wavenumber region of 650–950 cm-1 are attributed to stretching vibrations of Mo–O bonds.The temperature-dependent Raman spectra reveal that K_2 Sr（MoO_4）2 exhibits two sets of modifications in the Raman spectra at ～ 150？C and ～ 475？C, attributed to structural phase transitions. The large change of the Raman spectra in the temperature range of 150？C to 475？C suggests structural instability of the medium-temperature phase β-K_2 Sr（MoO_4）2.
