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Lead-free (Bi0.5Na0.5)1-xSrxBi4Ti4O15 ceramics (x = 0–0.9) are fabricated by solid state reaction process. XRD analysis shows the symmetry divergence from tetragonal to orthorhombic phase accompanied by morphotropic phase boundary with increasing strontium content. Raman spectra confirm the incorporation of strontium into (Bi2.5Na0.5Ti4O13)2- layers. SEM graphs exhibit the typical plate-like morphology with regular variation of grain size and crystallization as strontium increases. Multistage ferroelectric transition is observed with x = 0.2–0.4. Piezoelectric performance measurements present the well thermal stability at x = 0.4. The dielectric properties display a shifting of Curie temperature towards low temperature with increasing strontium ions. It can be due to the crystal lattice distortion by larger radius of strontium and the increasing tolerance factor. ac conductivity and impedance measurements suggest that electron hopping mainly contributes to the low temperature region. Ionization conductivity by oxygen vacancy migration including first-ionization and double-ionization plays the dominating role in the middle and high temperature region. The controllable properties indicate the potential applications for electric devices of (Bi0.5Na0.5)1-xSrxBi4Ti4O15 ceramic.

Lead-free Bi4Ti3O12/NiFe2O4 nanocomposite films have been prepared via sol-gel spin-coating route. The successful phase formation of orthorhombic Bi4Ti3O12 and cubic NiFe2O4 has been confirmed using x-ray diffraction without any detectable extra phase. The scanning electron microscopy with EDS measurement reveals homogeneous and dense growth of both phases accompanied by clear interface between the two layers. The loop of magnetization versus magnetic field indicates the ferromagnetic properties at room temperature with saturation magnetization of ~257.48 emu/cm3, coercive field of ~121 Oe and remnant magnetization of ~57.03 emu/cm3. Room-temperature ferroelectric behavior is also obtained along with the good fatigue endurance properties and low leakage current density. The frequency dependence of dielectric constant displays the monotonous decreasing tendency with low dielectric loss. Moreover, evident magnetodielectric behavior is achieved in the nanocomposite films at room temperature. The coexistence of ferromagnetic and ferroelectric behavior including the appearance of magnetodielectric effect proves the room-temperature multiferroic properties in Bi4Ti3O12/NiFe2O4 nanocomposite films, which makes the films meaningful as the lead-free multiferroic systems for device applications at room temperature.

Intergrowth ceramic series Bi4Ti3O12/Bi4.5Na0.5Ti4O15 have been prepared through solid state reaction. X-ray diffraction analysis shows the coexistence of Bi4Ti3O12 and Bi4.5Na0.5Ti4O15 phases with slight lattice distortion. Scanning electron micrographs present the growth of grains and grain boundaries with different contents of Bi4.5Na0.5Ti4O15. The relaxation dielectric properties of the ceramics have been observed. The room-temperature dielectric constant at 100 Hz is initially increased and then decreased with the increase of Bi4.5Na0.5Ti4O15. The impedance spectroscopy and the electrical modulus are also measured for explaining the dielectric behavior. The Nyquist plots display different semicircle arcs at 300 and 600 K. The imaginary part of electrical modulus has two peaks in the range of the measuring temperature. They prove the common influence of grains and grain boundaries on the dielectric properties. For further fitting the experimental data by Arrhenius theory, activation energy is obtained for grains and grain boundaries. Finally, the relaxor dielectric properties are attributed to the competition mechanism from the different growth situation of grains and grain boundaries with increasing Bi4.5Na0.5Ti4O15. Therefore, this kind of ceramics ought to be promising candidates for multifunctional device applications.

Exchange bias behaviors up to room temperature have been observed in NiCo2O4/NiO nanoparticle system. The field-cooled magnetic hysteresis loops exhibit shifts both in the field and magnetization axes simultaneously. The variation of exchange bias field and magnetization shift depends strongly on the measuring temperature. In addition, the dependence of exchange bias effect on measuring temperature is not monotonous, which is reflected in the different tendency during the decrease process of magnetization shift and exchange bias field. The exchange bias field is decreased firstly at the range of 10–50 K followed by an increase of 50–200 K and decreased again of 200–320 K. By analyzing various magnetic measurements, the special exchange bias effect in NiCo2O4/NiO can be owing to the spin glass state and the ferrimagnetic/antiferromagnetic coupling during different temperature ranges.

Epitaxial PbTiO3 films with a smooth and dense surface were fabricated by a promising hydrothermal synthesis on an Nb:SrTiO3(100) substrate. The resulting coated substrate was used to fabricate a Pt/PbTiO3/Nb:SrTiO3 heterostructure device. The device exhibited a multilevel storage capacity with an appropriate R OFF / R ON ratio and excellent endurance and retention. An electric conduction analysis indicated that the resistive switching behavior of the device was attributed to the trap controlled space-charge-limited current conduction that was caused by the oxygen vacancies in the PbTiO3 hydrothermal films. The modulation of the Pt/PbTiO3 Schottky-like junction depletion under an applied electric field is thought to be responsible for the resistive switching behavior of the device in the carrier injection-trapped/detrapped process.

The polycrystalline xBi0.5Na0.5TiO3-(1-x)NiFe2O4 solid solutions with different ratios have been synthesized by sol-gel method. The samples are respectively annealed with nonmagnetic and magnetic field annealing processes. X-ray diffraction patterns present the pure formation with coexistence of Bi0.5Na0.5TiO3 and NiFe2O4 phases. Micrographs measured with scanning electron microscope show the dense surface morphology. Evident enhancement in electric polarization and magnetoelectric coupling coefficient is observed with magnetic field annealing. As the content of Bi0.5Na0.5TiO3 increases, magnetoelectric effect is most prominent at the ratio of x = 0.7 with magnetic field annealing. These results indicate the successful influence on room-temperature magnetoelectric coupling effect by magnetic field annealing.

The 0.7(Bi 0.5 Na 0.5 ) 1- x Ba x TiO 3 -0.3NiFe 2 O 4 samples ( x = 0.02–0.12) have been synthesized through sol-gel method. Structure, micromorphology and the room-temperature multiferroic properties have been investigated, respectively. The characterization of structure and micromorphology reveals the coexistence of two different phases. In addition, lattice deformation and morphology variation can be clearly confirmed with doping Ba ions. Dielectric properties are improved evidently from x = 0.02–0.08 and then weakened from x = 0.08–0.12 with enough low values of dielectric loss for all the samples. The ferroelectric polarization demonstrates that room-temperature ferroelectric properties are monotonously enhanced with increasing content of Ba. The change tendency of magnetic properties is firstly decreasing and then increasing with the special content value of x = 0.08. Room-temperature magnetoelectric coupling effect is verified by the measurement of magnetoelectric coupling coefficient. The variation trend of magnetoelectric coupling coefficient with doping of Ba is similar to that of magnetic properties. The room-temperature multiferroic properties of 0.7(Bi 0.5 Na 0.5 ) 1- x Ba x TiO 3 -0.3NiFe 2 O 4 samples are related to the larger ionic radius of Ba. Furthermore, the special multiferroic behavior with x = 0.08 can be attributed to the morphotropic phase boundary effect with doping Ba.

High-quality CH3NH3PbI 3−xClx (MAPIC) films were prepared using potassium chloride (KCl) as an additive on indium tin oxide (ITO)-coated glass substrates using a simple one-step and low-temperature solution reaction. The Au/KCl-MAPIC/ITO/glass devices exhibited obvious multilevel resistive switching behavior, moderate endurance, and good retention performance. Electrical conduction analysis indicated that the resistive switching behavior of the KCl-doped MAPIC films was primarily attributed to the trap-controlled space-charge-limited current conduction that was caused by the iodine vacancies in the films. Moreover, the modulations of the barrier in the Au/KCl-MAPIC interface under bias voltages were thought to be responsible for the resistive switching in the carrier injection trapping/detrapping process.

Double perovskites Re2CoMnO6 (Re=Sm, Dy) have been synthesized by a solid-state reaction method. Magnetic field-induced metamagnetic behavior is observed in the samples below the ferromagnetic Curie temperature (TC), which are respectively 123 K and 88 K in Sm2CoMnO6 and Dy2CoMnO6. The origin of this effect is attributed to the competition between the nearest-neighbor ferromagnetic super-exchange interaction (Co2+-Mn4+) and the next nearest-neighbor antiferromagnetic exchange interaction (Co2+-Co2+, Mn4+-Mn4+). Arrott plots combined with the thermal hysteresis confirm that the transition from ferromagnetic to antiferromagnetic state with negative slope is the first-order magnetic phase transition. Moreover, the positive slope closely to TC indicates that the transition from paramagnetic to ferromagnetic state is the second-order transition. Magnetocaloric effect associated with Maxwell's relation is studied and the maximal value of | Δ S M | is 1.4 and 3.5 J kg−1 K−1 at 6 T near TC for Sm2CoMnO6 and Dy2CoMnO6. The large value of | Δ S M | for Dy2CoMnO6 is obtained which is 9.1 J kg−1 K−1 at 20 K. The relatively smaller magneto entropy change for Sm2CoMnO6 may be attributed to the higher coercive field and the weaker magnetism.

Polycrystalline (1-x)(0.75Bi4Ti3O12-0.25Bi0.5Na0.5TiO3)-xMgFe2O4 lead-free composites were prepared through sol-gel process with different stoichiometric proportions. The influence of proportions on microstructure, morphology, magnetic and dielectric behaviors has been explored detailedly. XRD patterns and Raman measurement reveal the multiphase coexistence with increasing content of MgFe2O4 of all the samples. The surface morphology presents different distributions of grain size for different proportions. The average grain size is confirmed to decrease as the MgFe2O4 concentration increases. Room-temperature magnetic properties are evidently enhanced by increasing addition of MgFe2O4. The giant effective permittivity at room temperature is obtained for all the samples with order of magnitude of 104∼105. The variation of dielectric properties including effective permittivity and dielectric relaxation is strongly dependent on the content of MgFe2O4. Through rigorous analysis, the dielectric behavior should result from the common contributions of different conductivities and morphology variation due to the incorporation of MgFe2O4 to Bi4Ti3O12-Bi0.5Na0.5TiO3.

Materials with tunable photoluminescence (PL) are highly desirable. It can lead to important applications such as photodetectors, bio-imaging, and broadband modulators. In this work, nitrogen-doped graphene oxide quantum dots (NGOQDs) were synthesized by hydrothermal method. The microstructures as well as optical properties of NGOQDs were studied. The as-prepared NGOQDs present tunable PL and exhibit a maximal PL blue-shift of ca. 88 nm compared to that of the graphene oxide quantum dots (GOQDs). The observed PL blue-shift of the NGOQDs is attributed to the high content of pyridine-like and pyrrolic-like nitrogen atoms doping in the NGOQDs. Our proposed mechanism for the PL blue-shift of the NGOQDs is supported by density functional theory (DFT) calculations.

NiCr2O4 nanoparticles have been successfully prepared by chemical co-precipitation method. Desired crystallographic phase of NiCr2O4 is confirmed by analyzing x-ray diffractrograms. With increasing annealing temperature, crystal transition from cubic to tetragonal phase is observed. The increasing average particle size from ∼80 to ∼280 nm is studied by SEM and TEM micrographs as annealing temperature increases. Exchange bias behavior is detected at 10 K accompanied by the shift of magnetic hysteresis loops along field axis. This effect is gradually weakening as annealing temperature increases. The magnetization depending on temperature under zero-field-cooled and field-cooled conditions suggests the ferrimagnetic transition at ∼72 K and the spiral magnetic order at ∼25 K. Furthermore, the ferrimagnetic transition point shifts slightly to low temperature with increasing annealing temperature. Based on the measurement results, the appearance and evolution of exchange bias effect in NiCr2O4 nanoparticles with improving annealing temperature should be simultaneously derived from the lattice transition and the surface spin effects.

The electromagnetic environment around the Experimental Advanced Superconducting Tokamak (EAST) device is very complex during plasma discharge experiment. In order to fully monitor the changes of electric field around the EAST device during plasma discharge, a transient electric field measurement system based on PCI eXtensions for Instrumentation (PXI) platform has been designed. A digitizer is used for high-speed data acquisition of raw signals from electric field sensors, and a Field Programmable Gate Array (FPGA) module is used for realizing an on-the-fly fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) algorithm including a beforehand identified antenna factor (AF) to achieve finally a calibrated and filtered electric field measurement, then these signals can be displayed and easily analyzed. The raw signals from electric field sensors are transferred through optical fiber by optical isolation to reduce electromagnetic interference (EMI). The high speed data streaming technology is used for data storage. A prototype of this system has been realized to measure the transient electric field strength, with the real-time processing and continuous acquisition ability of one channel of 14-bit resolution and up to 50 MHz sampling rate, and 6 KHz FFT frequency resolution.

Single phase NiCr2O4 has been successfully prepared by sol–gel technique. Characterization of crystal and morphology exhibits the tetragonal structure and homogeneous growth with regular crystalline shape. Large dielectric constant of ~2447 is observed at room temperature. The relaxation behavior below room temperature is confirmed through measurements of dielectric constant, dielectric loss, electric modulus and impedance depended on frequency or temperature. The analysis through equivalent circuit simulation demonstrates the influence of grains at low temperature and the common contribution of grains and grain boundaries at high temperature. Moreover, the change in dielectric response indicates the presence of magnetodielectric coupling effect. Two different mechanisms are considered to control the magnetodielectric coupling, yielding the positive and negative coupling coefficient at different temperature ranges. The intrinsic magnetoelectric coupling gives rise to the frequency independent magnetodielectric behavior at low temperature. As temperature increases above 150 K, the large magnetodielectric coupling coefficient depended on frequency is contributed by the Maxwell-Wagner effect. The negative value of magnetodielectric coupling coefficient is attributed to the leakage current. Therefore, both mechanisms of Maxwell-Wagner and leakage are competing as a function of frequency, which results in the coefficient crossover at room temperature. Such features bring NiCr2O4 a step closer to potential applications in areas such as magnetic field sensors, actuators and others.

High temperature superconducting (HTS) material B-2223/Ag-Au has been used for EAST poloidal field (PF) coil current leads for reducing construction and operation cost of cryogenic system. The quench propagation velocity of HTS superconducting material is several orders of magnitude lower than that of normal low temperature current leads. It is difficult to detect weak signal of quench which is easily influenced by strong electromagnetic interference (EMI). In this paper, the sources of EMI from quench detecting system of high temperature current leads have been introduced. And we have chosen reasonable methods for good transformation and protection on the basis of electromagnetic compatibility simulation diagnosis experiments. Recent experimental results showed that the restraint of EMI has been achieved and has met the requirements of experiment.

The microstructure evolution characteristics and those effects on microhardness of HSLA (high strength low alloy) 100 steel secondary quenched in the two-phase region were investigated. The results show that the mixed microstructure of ferrite and the M-A（mastenite-austenite）islands can be obtained in the intercritical quenching region. A small amount of island structure distributing along the lath ferrite quenched at 700°C is observed by transmission electron microscope (TEM). With the quenching temperature increasing, the island structure increases in quantity and coarsens in shape, at the same time, the ferrite gradually transform from single lath morphology to polygonal shape with the dislocation density lowing. When quenched at 820°C, the microstructure reverts to lath bainite. There is a good correlation between Vickers hardness value and the volume fraction of martensite or bainite HSLA100 steel quenched in the two-phase region. The microhardness value of the steel continually increase from 240HV to 320HV quenched at the range of 700°C to 820°C, and then keep a very small fluctuation around 320HV when the temperature exceeds to 820°C.

In this study, we reported the analysis of DGAT2 gene polymorphisms in 468 goats of two breeds: Xinong Saanen (SN) and Guanzhong (GZ). We identified three new allelic variants: P2 (C234A), P4 (C182T) and P5 (G301T) in SN and GZ breeds. Furthermore, P2 locus was a missense mutation (Leu > Met) in both breeds. Three genotypes were found at P2 (CC, CD and DD) and P4 (AA, AB and BB) loci in SN and GZ breeds, respectively. At P5 locus, EE and EF genotypes were found in both breeds. The SNP loci were in Hardy–Weinberg disequilibrium at P2 and P5 loci in SN and GZ breeds (P 0.05). Association of polymorphisms with milk yield and fat percentage was done in both breeds, which showed that genotypes CC, CD (P2 locus) and EE (P5 locus) had higher milk yield and fat percentage. Some of those with better performance could be used for the breeding of improved genotypes of goat. Therefore, these results suggest that DGAT2 gene is a strong candidate gene that affects milk yield and fat percentage in goat.

During 1981-83, we identified nutrient requirements and fertilizer strategies for the development of legume-based pastures in dry tropical rangelands of Hainan Island, China. Nutrient requirements for pastures grown on sandy and red loam soils were established using soil tests and missing element experiments with 3 test legumes. An acute P deficiency ( 20 mg kg-1. In contrast, application of P fertilizer proved both profitable and essential for development of legume-based pastures on P-deficient sandy soils. It is recommended that a rate of about 40 kg of P ha-1 should be applied at establishment of stylo pastures on sandy soil. At this rate both legume yield and P content of tops should be maintained at levels needed to sustain a beef production enterprise and return about $1.5 per dollar invested in fertilizer.

Seedbed requirements for the establishment of grasses and legumes were studied in 3 experiments conducted over 3 years (1981-83) on the sandy ( 20 mg kg-1 Bray P) ultisol soils found in the dry tropical rangelands of western Hainan Island, China. Density at the end of the wet season and production accumulated over the growing season (May-October) were the discriminative parameters used. Experiment 1 measured the effect of seedbed preparation (cultivated and uncultivated but heavily grass pasture) on the establishment of 2 grasses, buffel (Cenchrus ciliaris L. cv. Biloela) and sabi (Urochloa mosambicensis (Hack.) Dandy cv. Nixon), sown alone or mixed with 3 stylos (Stylosanthes guianensis (Aubl.) Sw. var. guianensis cv. Graham, S. hamata (L.) Taub. cv. Verano and S. scabra Vog. cv. Seca) on the 2 soil types. Biloela buffel established better and produced more in subsequent years than Nixon sabi grass when sown on a cultivated seedbed, but neither grass established when sown into undisturbed grassland. Companion stylos established on both seedbeds, but initial density and yield was lower on the uncultivated seedbed. However, in 3-year-old swards, stylo yield on uncultivated seedbeds equalled or exceeded yield on cultivated seedbeds. Seca was the most productive stylo, but Graham yielded more consistently between years. Soil type had no effect on sown grass production, but legumes grew better on the sandy soil. Experiment 2 measured the effect of 4 seedbeds (heavily grazed, 1 disking, sprayed with herbicide, and cultivated to fine tilth) on establishment on Verano and Seca stylos on sandy soil. Density of both stylos was highest where grass competition was minimized with herbicide and lowest where heavy grazing was imposed prior to seeding. Compared to herbicide, disking resulted in lower density and yield in the establishment year, but the difference disappeared with time. Burial of seed too deeply and subsequent competition from native species account for the poor performance of both stylos when drilled into a cultivated seedbed which was still evident in 3-year-old swards. Experiment 3 examined the interaction between seedbed type (heavily grazed, burnt, 1 disking, sprayed with herbicide) and superphosphate application. Superior establishment was measured on herbicide and disked treatments and production was still higher in 3-year-old swards than heavy grazing. Burning was more effective than heavy grazing. Increasing fertilizer input improved legume production on all seedbeds, but did not affect density. Reduction in legume yield between 2- and 3-year-old swards in the burnt and disked treatment due to grass competition highlights the need for appropriate grazing to maintain legume content of augmented grasslands. Overall we recommend rough disking as the most practical and cost-effective means to augment native grasslands with stylos. A fine seedbed is recommended to provide the disturbance required to establish grasses. There is no advantage gained by including grasses with legumes oversown into living grassland.

During 1981-83, we studied 19 grasses for potential improvement of dry tropical (1,001 mm annual rainfall) rangelands in Hainan Island, China. The productivity and persistence of the grasses were tested on sandy ( 5 plants/m2), but only 6 cultivars produced yields > 1.5 metric tonne (t)/ha. Melinis minutiflora Beauv., Brachiaria decumbens Stapf. and Chloris gayana Kunth. yielded more than 1.5 t/ha in 3-year-old swards on both soils, whereas Panicum maximum Jacq. and Setaria sphacelata (Schum.) Stapf. ex Massey only performed well on fertile loam soil. Grass establishment was superior on sandy soil, but plant density did not correlate well with production which was higher on red loam soil due to better waterholding capacity and nutrient status. Compatibility of these successful grasses with companion legumes was low with legumes contributing 4 t/ha. S. sphacelata was the only grass to form a stable mixture with companion legumes. [Macroptilium atropurpurem (D.C.) Urban and Stylosanthes guianensis (Aubl.) Sw.], which yielded more than 1.1 t/ha in 3-year-old swards on loam soil. This combination was recommended for improvement of loam soil rangelands. It is concluded from this study that range improvement with perennial grasses is confined to fertile soils, while direct broadcast of Stylosanthes legumes only into grazed native pastures is the practice recommended for improvement of infertile sandy soil until persistent low P tolerant grasses are found for the dry tropics.