Hematite(α-Fe_(2)O_(3))is known to undergo conversion from weak ferromagnetic to antiferromagnetic as the temperature decreases below the Morin temperature(TM=250 K)due to spin moment rotation occurring during the Mo...Hematite(α-Fe_(2)O_(3))is known to undergo conversion from weak ferromagnetic to antiferromagnetic as the temperature decreases below the Morin temperature(TM=250 K)due to spin moment rotation occurring during the Morin transition(MT).Herein,we endowed hematite with mesostructured chirality to maintain weak ferromagnetism without MT.Chiral mesostructured hematite(CMH)nanoparticles were prepared by a hydrothermal method with glutamic acid(Glu)as the symmetry-breaking agent.The triangular bipyramidal CMH nanoparticles were composed of helically cleaved nanoflakes with twisted crystal lattice.Field-cooled(FC)magnetization measurements showed that the magnetic moments of CMH were stabilized without MT within the temperature range of 10–300 K.Hysteresis loop measurements confirmed the weak ferromagnetism of CMH.The enhanced Dzyaloshinskii–Moriya interaction(DMI)was speculated to be responsible for the temperature-independent weak ferromagnetism,in which the spin configuration would be confined with canted antiferromagnetic coupling due to the mesostructured chirality of CMH.展开更多
In this paper, a novel technique is presented for an FBG with the step-coated polymers, which can be used for the measurement of the temperature-independent pressure in the temperature range between 5 and 50℃.
In order to explore the high temperature stability of ceramic capacitor,we present temperatureindependent dielectric properties of 0.82[0.94Bi_(0.5)Na_(0.5)TiO_(3)-0.06BaTiO_(3)]-0.18K_(0.5)Na_(0.5)NbO_(3)(BNT-BT-18KN...In order to explore the high temperature stability of ceramic capacitor,we present temperatureindependent dielectric properties of 0.82[0.94Bi_(0.5)Na_(0.5)TiO_(3)-0.06BaTiO_(3)]-0.18K_(0.5)Na_(0.5)NbO_(3)(BNT-BT-18KNN)ceramics.For different sintered temperature and annealing treatment,the pseudoternary system showed aεr of 2265 at 1 kHz at 35℃with a normalized permittivity ε/ε35℃varying less than±15%from 11℃to 382℃.This pure perovskite phase with slimmer and heat proof PE loops possessed energy density of 0.616 J/cm^(3)with a tolerance of about3%in a temperature interval ranging from 20℃to 120℃,which is higher and more temperature stable than most ceramic capacitors,such as PLZST and 0.89BNT0.06BT0.05KNN.This relaxor ferroelectric(at room temperature)with parabolic bipolar strainelectric(S(E))curve showed a quite low temperature dependence of positive strain with less than±6.5%tolerance from the average value of 0.091%between 20℃and 120℃,which is also more temperature stable than the same composition Zhang et al.reported.These merits demonstrate that the newly produced BNT-BT-18KNN ceramics should be a promising candidate for the development of high-temperature capacitor and actuator materials.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21931008,21873072,21922304,and 21975184)the National Key R&D Program of China(No.2021YFA1200301)+2 种基金Fundamental Research Funds for the Central Universities,Shanghai Pilot Program for Basic Research-Shanghai Jiao Tong University(No.21TQ1400219)Natural Science Fund for Colleges and Universities in Jiangsu Province(No.22KJB150041)Wuxi"Taihu Light"Science and Technology Project-Basic Research(No.K20221067).
文摘Hematite(α-Fe_(2)O_(3))is known to undergo conversion from weak ferromagnetic to antiferromagnetic as the temperature decreases below the Morin temperature(TM=250 K)due to spin moment rotation occurring during the Morin transition(MT).Herein,we endowed hematite with mesostructured chirality to maintain weak ferromagnetism without MT.Chiral mesostructured hematite(CMH)nanoparticles were prepared by a hydrothermal method with glutamic acid(Glu)as the symmetry-breaking agent.The triangular bipyramidal CMH nanoparticles were composed of helically cleaved nanoflakes with twisted crystal lattice.Field-cooled(FC)magnetization measurements showed that the magnetic moments of CMH were stabilized without MT within the temperature range of 10–300 K.Hysteresis loop measurements confirmed the weak ferromagnetism of CMH.The enhanced Dzyaloshinskii–Moriya interaction(DMI)was speculated to be responsible for the temperature-independent weak ferromagnetism,in which the spin configuration would be confined with canted antiferromagnetic coupling due to the mesostructured chirality of CMH.
文摘In this paper, a novel technique is presented for an FBG with the step-coated polymers, which can be used for the measurement of the temperature-independent pressure in the temperature range between 5 and 50℃.
基金supported by the Ministry of Sciences and Technology of China through 973-project(Grant No.2009CB623306)the National Natural Science Foundation of China-NSAF(Grant Nos.10976022,10875095 and 50872107)International Science&Technology Cooperation Program of China(Grant No.2010DFR50480).
文摘In order to explore the high temperature stability of ceramic capacitor,we present temperatureindependent dielectric properties of 0.82[0.94Bi_(0.5)Na_(0.5)TiO_(3)-0.06BaTiO_(3)]-0.18K_(0.5)Na_(0.5)NbO_(3)(BNT-BT-18KNN)ceramics.For different sintered temperature and annealing treatment,the pseudoternary system showed aεr of 2265 at 1 kHz at 35℃with a normalized permittivity ε/ε35℃varying less than±15%from 11℃to 382℃.This pure perovskite phase with slimmer and heat proof PE loops possessed energy density of 0.616 J/cm^(3)with a tolerance of about3%in a temperature interval ranging from 20℃to 120℃,which is higher and more temperature stable than most ceramic capacitors,such as PLZST and 0.89BNT0.06BT0.05KNN.This relaxor ferroelectric(at room temperature)with parabolic bipolar strainelectric(S(E))curve showed a quite low temperature dependence of positive strain with less than±6.5%tolerance from the average value of 0.091%between 20℃and 120℃,which is also more temperature stable than the same composition Zhang et al.reported.These merits demonstrate that the newly produced BNT-BT-18KNN ceramics should be a promising candidate for the development of high-temperature capacitor and actuator materials.
