Implementation of manganese–bismuth(MnBi)alloys as high-performance permanent magnets is a challenge for physicists and engineers because the ferromagnetic low-temperature phase(LTP)is not exclusively obtained.In thi...Implementation of manganese–bismuth(MnBi)alloys as high-performance permanent magnets is a challenge for physicists and engineers because the ferromagnetic low-temperature phase(LTP)is not exclusively obtained.In this work,melting powered by four commercial magnetrons of 2000–2500 W in a microwave furnace is demonstrated as a new route to alloy MnBi.Under an argon atmosphere,microwave heating transferred to pieces of broken Bi ingots and Mn flakes for 2 h gave rise to products of inhomogeneous composition and morphology.Scanning electron micrographs were classified into three regions according to morphology and elemental composition.Cubic-like clusters characterized as Mn precipitated over light solidified Bi-rich regions,and the MnBi phase was formed in homogeneous regions with a balanced composition between Mn and Bi.A ferromagnetic hysteresis loop was obtained in the ground powder with a coercivity of 40 kA/m.Subsequent annealing at 553 K under a pressure of 414 kPa for 12 h enhanced the MnBi phase with extended regions of balanced composition.It follows that the coercivity was increased to 60 kA/m.However,remanent magnetization was slightly reduced.This MnBi alloyed by microwave radiation can be further used in rare-earth-free magnets.展开更多
Alcohol effects in a series of iron(III)spin crossover complexes[Fe(qsal-Cl)_(2)]NO_(3)·ROH(R=Me 1,Et 2,1-Pr 3)are explored.Despite the solvents differing from each other by only one or two CH_(2) groups,unique p...Alcohol effects in a series of iron(III)spin crossover complexes[Fe(qsal-Cl)_(2)]NO_(3)·ROH(R=Me 1,Et 2,1-Pr 3)are explored.Despite the solvents differing from each other by only one or two CH_(2) groups,unique packing motifs are observed for each complex.While 1 crystallizes in triclinic P[1 with combining macron]with two independent iron(III)centres,connecting them in a tight undulating 1D chain with a rectangular cross-section,2(monoclinic P2_(1)/c)and 3(monoclinic I2/a)crystallize with only one iron center.For 2,a linear 1D chain is observed with a square cross-section,while 3 exhibits a looser 1D chain formed by dimers.The 3D supramolecular networks are distinctive with 1 showing identical parallelogram shaped 2D sheets,whereas 2 and 3 show alternating 2D sheets with differing staggering between the layers(AB).These results are supported by Hirshfeld surface analysis.The magnetic studies show no significant SCO for 1 and 3.However,2 shows an incomplete gradual spin transition(T_(1/2)=200 K).Moreover,upon partial ethanol desolvation,a 25 K hysteresis near room temperature(T_(1/2)↓=275 K,T_(1/2)↑=300 K)is observed.The packing observed in 2 is present in many other[Fe(qsal-X)2]+complexes with hysteresis and abrupt SCO.DFT calculations using the r^(2)SCAN functional quantify the differences for 1 and 2 in the low-high spin energy and their cooperative effects.This study illustrates that even small changes in the solvent can dramatically influence the crystal packing and therefore the SCO properties.展开更多
基金Project(ThEP-60-PIP-WU3)supported by the Thailand Center of Excellence in Physics。
文摘Implementation of manganese–bismuth(MnBi)alloys as high-performance permanent magnets is a challenge for physicists and engineers because the ferromagnetic low-temperature phase(LTP)is not exclusively obtained.In this work,melting powered by four commercial magnetrons of 2000–2500 W in a microwave furnace is demonstrated as a new route to alloy MnBi.Under an argon atmosphere,microwave heating transferred to pieces of broken Bi ingots and Mn flakes for 2 h gave rise to products of inhomogeneous composition and morphology.Scanning electron micrographs were classified into three regions according to morphology and elemental composition.Cubic-like clusters characterized as Mn precipitated over light solidified Bi-rich regions,and the MnBi phase was formed in homogeneous regions with a balanced composition between Mn and Bi.A ferromagnetic hysteresis loop was obtained in the ground powder with a coercivity of 40 kA/m.Subsequent annealing at 553 K under a pressure of 414 kPa for 12 h enhanced the MnBi phase with extended regions of balanced composition.It follows that the coercivity was increased to 60 kA/m.However,remanent magnetization was slightly reduced.This MnBi alloyed by microwave radiation can be further used in rare-earth-free magnets.
基金the National Research Council of Thailand(NRCT)grant number NRCT5-RSA63019-02the Thailand Science Research and Innovation Fund(Contract No.FRB650082/227)for funding+2 种基金The National Science Technology and Innovation Policy Office for Integrated Research and Innovation Plan(Grant No.256113A3050001)is thanked for funds to purchase an X-ray diffractometerVidyasirimedhi Institute of Science and Technology is thanked for elemental analysisthe Spanish Ministerio de Ciencia e Innovación(PGC2018-093863-B-C21 and MDM-2017-0767)。
文摘Alcohol effects in a series of iron(III)spin crossover complexes[Fe(qsal-Cl)_(2)]NO_(3)·ROH(R=Me 1,Et 2,1-Pr 3)are explored.Despite the solvents differing from each other by only one or two CH_(2) groups,unique packing motifs are observed for each complex.While 1 crystallizes in triclinic P[1 with combining macron]with two independent iron(III)centres,connecting them in a tight undulating 1D chain with a rectangular cross-section,2(monoclinic P2_(1)/c)and 3(monoclinic I2/a)crystallize with only one iron center.For 2,a linear 1D chain is observed with a square cross-section,while 3 exhibits a looser 1D chain formed by dimers.The 3D supramolecular networks are distinctive with 1 showing identical parallelogram shaped 2D sheets,whereas 2 and 3 show alternating 2D sheets with differing staggering between the layers(AB).These results are supported by Hirshfeld surface analysis.The magnetic studies show no significant SCO for 1 and 3.However,2 shows an incomplete gradual spin transition(T_(1/2)=200 K).Moreover,upon partial ethanol desolvation,a 25 K hysteresis near room temperature(T_(1/2)↓=275 K,T_(1/2)↑=300 K)is observed.The packing observed in 2 is present in many other[Fe(qsal-X)2]+complexes with hysteresis and abrupt SCO.DFT calculations using the r^(2)SCAN functional quantify the differences for 1 and 2 in the low-high spin energy and their cooperative effects.This study illustrates that even small changes in the solvent can dramatically influence the crystal packing and therefore the SCO properties.
