Piezoelectric properties of low loss and high Curie temperature (Bi, La)FeO_3-Pb(Ti, Mn)O_3 ceramics with Mn doping

Piezoelectric ceramics of 0.6(Bi0.9La0.1)FeO3-0.4Pb(Ti1-xMnx)O3 (BLF-PTM) for x=0, 0.01, 0.02, and 0.03 were prepared by sol-gel process combined with a solid-state reaction method. The tan? for BLF-PTM of x=0.01 is just 0.006 at 1 kHz, drastically decreasing by using Mn dopants. The TC increases to 490 ℃ for BLF-PTM of x=0.02. Furthermore, Mn modification effectively enhances the poling state and the piezoelectric properties of BLF-PTM. The kp, Qm, d33, and g33 of 0.34, 403, and 124 pC1·N-1 and 37×10-3 Vm·N-1 are achieved for BLF-PTM of x=0.01. The results indicate that Mn modified BLF-PTM is a competitive high power and high temperature piezoelectric material with excellent piezoelectric properties.

High Ferroelectricities and High Curie Temperature of BiInO3PbTiO3Thin Films Deposited by RF Magnetron Sputtering Method

Properties of ferroelectric xBiInO3-（1-x）PbTiO3（xBI-（1-x）PT） thin films deposited on（101） SrRuO3/（200）Pt/（200） MgO substrates by rf magnetron sputtering method and effects of deposition conditions are investigated.The structures of the xBI-（1-x）PT films are characterized by x-ray diffraction and scanning electron microscopy.The results indicate that the thin films are grown with mainly（001） orientation. The chemical compositions of the films are analyzed by scanning electron probe and the results indicate that the loss phenomena of Pb and Bi elements depend on the pressure and temperature during the sputtering process.The sputtering parameters including target composition, substrate temperature, and gas pressure are adjusted to obtain optimum sputtering conditions. To decrease leakage currents,2 mol% La2 O3 is doped in the targets. The P-E hysteresis loops show that the optimized xBI-（1-x）PT（x = 0.24） film has high ferroelectricities with remnant polarization2 Pr = 80μC/cm2 and coercive electric field 2 EC = 300 kV/cm. The Curie temperature is about 640℃. The results show that the films have optimum performance and will have wide applications.

Spin transport of half-metal Mn_(2)X_(3) with high Curie temperature:An ideal giant magnetoresistance device from electrical and thermal drives

Currently,magnetic storage devices are encountering the problem of achieving lightweight and high integration in mobile computing devices during the information age.As a result,there is a growing urgency for twodimensional half-metallic materials with a high Curie temperature(TC).This study presents a theoretical investigation of the fundamental electromagnetic properties of the monolayer hexagonal lattice of Mn_(2)X_(3)(X=S,Se,Te).Additionally,the potential application of Mn_(2)X_(3) as magneto-resistive components is explored.All three of them fall into the category of ferromagnetic half-metals.In particular,the Monte Carlo simulations indicate that the TC of Mn2S3 reachs 381 K,noticeably greater than room temperature.These findings present notable advantages for the application of Mn2S3 in spintronic devices.Hence,a prominent spin filtering effect is apparent when employing non-equilibrium Green’s function simulations to examine the transport parameters.The resulting current magnitude is approximately 2×10^(4) nA,while the peak gigantic magnetoresistance exhibits a substantial value of 8.36×10^(16)%.It is noteworthy that the device demonstrates a substantial spin Seebeck effect when the temperature differential between the electrodes is modified.In brief,Mn_(2)X_(3) exhibits outstanding features as a highTC half-metal,exhibiting exceptional capabilities in electrical and thermal drives spin transport.Therefore,it holds great potential for usage in spintronics applications.

Enhanced piezoelectric properties of (Ba_(0.3)Bi_(0.7))(Mg_(0.05)Fe_(0.6)Ti_(0.35))O_(3) piezoelectric ceramics with high Curie temperature

(Ba_(0.3)Bi_(0.7))(Mg_(0.05)Fe_(0.6)Ti_(0.35))O_(3) ceramics were either doped with vanadium or sintered in calcined powder with the same composition.Compared to an undoped ceramic sintered without the calcined powder,both ceramics showed reduced leakage current densities(lower than 1×10^(-7) A/cm^(2))and absence of dielectric relaxation behaviors observed in frequency-and temperaturedependent dielectric measurements.The Curie temperatures of both samples were higher than 460℃.The maximum field-induced strain over the applied field,S_(max)/E_(max),of 366 pm/V of the undoped ceramic sintered without the calcined powder increased to 455 and 799 pm/V for the V-doped ceramics and the ceramics sintered with the calcined powder,respectively.The increase was related to a reduced concentration of bismuth vacancy-oxygen vacancy defect dipoles.

A room-temperature magnetic semiconductor from a Co-Fe-Nb-B metallic glass

Magnetic semiconductors with Curie temperatures higher than room temperature show potential for developing spintronic devices with combined data processing and storage functions for next-generation computing systems.In this study,we present an n-type Co_(19.8)Fe_(8.6)Nb_(4.3)B_(6.0)O_(61.3) magnetic semiconductor with a high Curie temperature of~559 K.This magnetic semiconductor has a room-temperature resistivity of~2.10×10^(4)Ωcm and a saturation magnetization of~76 emu/cm^(3).The n-type Co_(19.8)Fe_(8.6)Nb_(4.3)B_(6.0)O_(61.3)magnetic semiconductor was deposited on p-type silicon to form a heterojunction,exhibiting a rectifying characteristic.Our results provide the design principles for discovering high Curie temperature magnetic semiconductors with determined conduction types,which would play an essential role in realizing nonvolatile spin-based transistors that break free from the confines of currently established Si-based information technology.