The gallate salts are frequently employed as matrix for mechanoluminescence(ML)materials largely due to their plentiful defect energy levels and robust piezoelectric characteristics.Nevertheless,the ML performance of ...The gallate salts are frequently employed as matrix for mechanoluminescence(ML)materials largely due to their plentiful defect energy levels and robust piezoelectric characteristics.Nevertheless,the ML performance of specific gallate materials is inferior to that of sulfides and fluorides and thus requires improvement.To address this issue,it is essential to engineer appropriate lattice defects in order to facilitate the advancement of new elastic ML materials.Therefore,in the present study,a series of Ca_(3)Ga_(4)O_(9):0.01 Bi^(3+),xTb^(3+)(x=0.01,0.02,0.03,0.04,0.05 and 0.06)was synthesized using the traditional high-temperature solid-state method.Furthermore,a non-intrinsic defect control strategy utilising Bi^(3+)ions is presented,which serves to enhance the performance of calcium gallate.The ML intensity is enhanced by 112%in comparison to the undoped samples(concentration of Tb^(3+)is 0.04),resulting in an improved linearity between mechanical loading and ML intensity,along with the achievement of dualmode photoluminescence(PL).By analysing the crystal structure,PL,ML,and thermoluminescence(TL)properties of Ca_(3)Ga_(4)O_(9):Bi^(3+),Tb^(3+)(CGO:Bi^(3+),Tb^(3+)),coupled with the first principles calculations using density functional theory(DFT),the ML mechanism of CGO:Bi^(3+),Tb^(3+)was elucidated.This leads to the development of a versatile anti-counterfeiting device with both flexible and rigid multi-mode capabilities.展开更多
Understanding the role of lattice vibrations on first-order magnetic transitions is essential for their fundamental description, as well as for the optimization of the related functional properties. Here, we present a...Understanding the role of lattice vibrations on first-order magnetic transitions is essential for their fundamental description, as well as for the optimization of the related functional properties. Here, we present a first principles study on the lattice dynamics of the MnFeP_(0.5)Si_(0.5) compound. The phonon spectra are obtained by Density Functional Theory(DFT) calculations in combination with frozen phonon method.DFT calculations reproduce most of the features observed in experiments including the lattice softening across the magnetic phase transition and the pronounced shift of phonon peak. The site projected phonon density of states(pDOS) shows that the local vibrations of Mn atoms have an essential contribution to the overall lattice softening. Moreover, the local lattice vibrations of Mn atoms are rather featureless in the paramagnetic state(PM) and thus the total pDOS evolution across the transition appears to be dominated by Fe. The lattice vibrations of both Fe and Mn in the PM state are very sensitive to the local environment,which shows that the magnetic order and the local chemical environment are strongly coupled in this compound.展开更多
The exact solution for the bending problem of a free-end point loaded film- substrate cantilever with arbitrary film-to-substrate thickness ratio is obtained by using the basic mechanical equilibrium equation. And the...The exact solution for the bending problem of a free-end point loaded film- substrate cantilever with arbitrary film-to-substrate thickness ratio is obtained by using the basic mechanical equilibrium equation. And then the problem of design and optimization for microactuator buildup of film-substrate cantilever is discussed by taking into account the effect of geometrical and physical parameters of the cantilever components. Furthermore, the optimal condition for actuator application is presented and some theoretical problems are clarified. The results show that, in general, the greater the film-to-substrate thickness ratio, the higher the ability of taking load, namely the larger the exerted force of the cantilever when the thickness of substrate is kept constant. When the total thickness of the cantilever is kept constant, however, the free-end exerted force will experience a maximum and this maximum value of the exerted force will decrease with the increasing film-to-sub- strate stiffness ratio. Meanwhile, the optimal thickness ratio corresponding to this maximum exerted force also decreases with the increasing stiffness ratio. Whether for the cases of fixed substrate or fixed total thickness, the influence of Poisson’s ratio of two cantilever components on the exerted force is remarkable, and should not be neglected.展开更多
基金supported by the National Natural Science Foundation of China(12164034)the Natural Science Foundation of Inner Mongolia(2023LHMS01002)the Science and Technology Project of Shenzhen(JCYJ20220531102603007)。
文摘The gallate salts are frequently employed as matrix for mechanoluminescence(ML)materials largely due to their plentiful defect energy levels and robust piezoelectric characteristics.Nevertheless,the ML performance of specific gallate materials is inferior to that of sulfides and fluorides and thus requires improvement.To address this issue,it is essential to engineer appropriate lattice defects in order to facilitate the advancement of new elastic ML materials.Therefore,in the present study,a series of Ca_(3)Ga_(4)O_(9):0.01 Bi^(3+),xTb^(3+)(x=0.01,0.02,0.03,0.04,0.05 and 0.06)was synthesized using the traditional high-temperature solid-state method.Furthermore,a non-intrinsic defect control strategy utilising Bi^(3+)ions is presented,which serves to enhance the performance of calcium gallate.The ML intensity is enhanced by 112%in comparison to the undoped samples(concentration of Tb^(3+)is 0.04),resulting in an improved linearity between mechanical loading and ML intensity,along with the achievement of dualmode photoluminescence(PL).By analysing the crystal structure,PL,ML,and thermoluminescence(TL)properties of Ca_(3)Ga_(4)O_(9):Bi^(3+),Tb^(3+)(CGO:Bi^(3+),Tb^(3+)),coupled with the first principles calculations using density functional theory(DFT),the ML mechanism of CGO:Bi^(3+),Tb^(3+)was elucidated.This leads to the development of a versatile anti-counterfeiting device with both flexible and rigid multi-mode capabilities.
基金financially supported by the National Natural Science Foundation of China(Nos.11464037,51161017 and51531008)
文摘Understanding the role of lattice vibrations on first-order magnetic transitions is essential for their fundamental description, as well as for the optimization of the related functional properties. Here, we present a first principles study on the lattice dynamics of the MnFeP_(0.5)Si_(0.5) compound. The phonon spectra are obtained by Density Functional Theory(DFT) calculations in combination with frozen phonon method.DFT calculations reproduce most of the features observed in experiments including the lattice softening across the magnetic phase transition and the pronounced shift of phonon peak. The site projected phonon density of states(pDOS) shows that the local vibrations of Mn atoms have an essential contribution to the overall lattice softening. Moreover, the local lattice vibrations of Mn atoms are rather featureless in the paramagnetic state(PM) and thus the total pDOS evolution across the transition appears to be dominated by Fe. The lattice vibrations of both Fe and Mn in the PM state are very sensitive to the local environment,which shows that the magnetic order and the local chemical environment are strongly coupled in this compound.
基金Supported by the National Natural Science Foundation of China (Grant No. 10147203)the Program for New Century Excellent Talents in Uni-versity (Grant No. NCET-2005-0272)the Key Project of the Ministry of Education of China (Grant No. 206024)
文摘The exact solution for the bending problem of a free-end point loaded film- substrate cantilever with arbitrary film-to-substrate thickness ratio is obtained by using the basic mechanical equilibrium equation. And then the problem of design and optimization for microactuator buildup of film-substrate cantilever is discussed by taking into account the effect of geometrical and physical parameters of the cantilever components. Furthermore, the optimal condition for actuator application is presented and some theoretical problems are clarified. The results show that, in general, the greater the film-to-substrate thickness ratio, the higher the ability of taking load, namely the larger the exerted force of the cantilever when the thickness of substrate is kept constant. When the total thickness of the cantilever is kept constant, however, the free-end exerted force will experience a maximum and this maximum value of the exerted force will decrease with the increasing film-to-sub- strate stiffness ratio. Meanwhile, the optimal thickness ratio corresponding to this maximum exerted force also decreases with the increasing stiffness ratio. Whether for the cases of fixed substrate or fixed total thickness, the influence of Poisson’s ratio of two cantilever components on the exerted force is remarkable, and should not be neglected.
