Preparation of Sm_2Fe_(17)Alloys in Ca-Sm_2O_3-Fe System

Sm2Fe17alloyisanimportantprecursorforthe preparationofSm2Fe17Nxmagnet.Sincethenitrogen containedSm2Fe17(Sm2Fe17Nx)alloy,asapermanent magnetmaterial,possessesahigherCurietempera ture,largeranisotropyfield,betterresistancetooxi dationandthermalstability,and…     

Study on preparation technique and properties of magnetostrictive epoxy bonded Tb1-xPrx(Fe0.4Co0.6)1.93 composites

The magnetic and magnetostrictive properties of epoxy bonded Tb1-xPrx(Fe0.4Co0.6)1.93 (0.85≤x≤1.00) composites, prepared with different epoxy proportions using cold compression-molding technique, were investigated. It is found that the optimal conditions were with a compaction pressure of 100 MPa and a mass ratio of resin to powder of 5:100. The Tb0.1Pr0.9(Fe0.4Co0.6)1.93 composite rod had a high magnetostriction of 770 ppm at an applied magnetic field of 960 kA/m, whereas the Pr(Fe0.4Co0.6)1.93 composite reached 500 ppm at 400 kA/m. The good magnetostrictive properties of Pr(Fe0.4Co0.6)1.93 composite at low-field (≤400 kA/m) could be explained by its low anisotropy. These results indicated that the epoxy bonded Tb1-xPrx(Fe0.4Co0.6)1.93 rod samples for high Pr content of x=0.9-1.0 were of practical value.     

Effect of annealing process on magnetic properties of Sm（Co0.6Fe0.27Cu0.1Zr0.03）7.5 ribbons

Sm(Co0.6Fe0.27Cu0.1Zr0.03)7.5 ribbons were prepared by melt-spun method. The results showed that the remnant magnetization Mr and intrinsic coercivity Hci had a rapid increase when the heating rate increased from 5 to 10℃/min. But the increase of Mr and Hci were observed to be very little when the heating rate was further increased to 20℃/min. 10℃/min was the critical heating rate for obtaining high magnetic properties. The maximum values of Mr and Hci reached 0.70 T and 780.1 kA/m when the annealing temperature and annealing time were optimized to be 800℃ and 1 h, respectively. Proper second-step heat treatment could suppress the decrease of Hci when the cooling rate increased from 0.7 to 5 ℃/min, which could reduce the cooling time effectively.     

Study on Preparation and Properties of La2O3/MC Nylon Nanocomposites

MC nylon,monomer casting nylon,is a newtypeof engineering plastics,whichis synthesized by anion-ic polymerization with caprolactam as the major rawmaterial,under normal pressure,pouring directlyto amould preheatedto a certaintemperature.It has manyadvantages,such as low polymerized temperature,si mple technology,high crystallinity,low-cost,highequipment efficiency as well as good mechanical prop-erties,shock decrease but wear proof,corrosion-resis-ting,self-ubricant,chemicals-resisting,wide us…     

溶胶-凝胶法制备片式电感用纳米Ni0.5Zn0.5Fe2O4铁氧体材料

研究了溶胶凝胶法制备Ni0.5Zn0.5Fe2O4粉体过程中,原料浓度、PH值和反应温度等因素对最终产物性能的影响,确定出较佳的制备条件;以此条件制备的镍锌铁氧体粉末经X射线衍射分析,证明为尖晶石相,其平均晶粒度小于26nm;对生产浆料的工艺进行了探索,取得一定进展。     

Effect of super heat treatment on crystallization behavior and magnetic properties of Nd4.5Fe77B18.5 nanocomposites

Melt-spun Nd4.5Fe77B18.5 ribbons were prepared under various superheat temperatures.The microstructure characteristics,crystallization behavior,and subsequent magnetic properties of Fe3B/Nd2Fe14B nanocomposite magnets were investigated using X-ray diffraction,differential thermal analysis,and vibrating sample magnetometry.It was shown that melt spinning at different quenching temperatures caused the as-quenched ribbons to have distinctive crystallization behavior.Depending on superheat temperature,phase tra...     

Ni0．5Zn0．5La0．05Fe1.95O4铁氧体的制备与吸波性能研究

采用高分子凝胶法制备了Ni0．5Zn0．5La0．05Fe1.95O4铁氧体。当煅烧温度为600℃时,立方晶系尖晶石结构的Ni0．5Zn0．5La0．05Fe1.95O4相初步形成。掺杂稀土La后,Ni0．5Zn0．5La0．05Fe1.95O4铁氧体的吸波性能显著提高,吸收峰向高频移动,其电磁波反射率小于～10dB的频宽可达2．7GHz,最小反射率为-15．6dB。     

Effect of annealing process on structures and ferroelectric properties of Ca0.4Sr0.6Bi3.95Nd0.05Ti4O15 thin films

Ca0.4Sr0.6Bi3.95Nd0.05Ti4O15 (C0.4S0.6BNT) ferroelectric thin films were prepared on Pt/Ti/SiO2/Si substrates by sol-gel method. Ef-fect of annealing process (time and temperature) on structures and ferroelectric properties of C0.4S0.6BNT thin film was investigated. The relative intensity of (200) peak increased first then decreased with annealing temperature and became predominant at 800℃. In contrast, no evident change could be observed in the (001) peak. The remnant polarization (Pr) and coercive field (Ec) for C0.4S0.6BNT film annealed at 800℃ for 5 rain were 21.6 μC/cm2 and 68.3 kV/cm, respectively.     

Preparation and luminescence properties of orange-red Ba3Y4O9:Sm3+ phosphors

A novel orange-red emitting Ba₃Y₄O₉:Sm³⁺ phosphors were prepared by a high temperature solid-state reaction in air. X-ray diffraction (XRD), photoluminescence spectra, fluorescence decay and temperature-dependent emission spectra were utilized to characterize the structure and luminescence properties. The results show that the excitation spectrum includes a series of linear peaks at 350, 367, 382, 410, 424, 445, 470 and 495 nm, respectively. Under 410 nm excitation, the emission peaks were located at 574 nm (⁴G_5/2—⁶H_5/2), 608 nm (⁴G_5/2—⁶H_7/2), 659 nm (⁴G_5/2—⁶H_9/2) and 722 nm (⁴G_5/2—⁶H_11/2), respectively. The concentration quenching occurs when x equals 0.08 for Ba₃Y_4–xO₉:xSm³⁺ phosphor and its mechanism is ascribed to the dipole–dipole interaction. The chromaticity coordinates of Ba₃Y_3.92O₉:0.08Sm³⁺ phosphor are in the orange-red region. The temperature-dependent study shows that this phosphor has excellent luminescence thermal-stability. And the luminescence intensity of Ba₃Y_3.92O₉:0.08Sm³⁺ phosphor at 473 K only declines by about 25.75% of its initial intensity. The experimental data indicate that Ba₃Y₄O₉:Sm³⁺ phosphor may be promising as an orange-red emitting phosphor for white light emitting diodes.     

粉末特性对Sm2(Co,Cu,Fe,Zr)17永磁材料及性能的影响

在粉末冶金工艺生产Sm2(Co,Cu,Fe,Zr)17的过程中,粉末特性对材料的性能存在较大影响.本研究对气流磨和滚动球磨两种工艺所制备的粉末进行比较,通过粒度分析及显微镜观察,研究了粉末的粒径与形状对材料性能的影响.分析结果表明,气流磨所制备的粉末平均粒径为4.53μm,尺寸分布范围较窄,粉末颗粒成近似球状,所得材料磁性能参数中Br,(BH)max优于滚动球磨.     

Study of Magnetic Entropy Changes in Gd1-x Tx ( T = Ti, Cr, Fe and Cu) Alloys

Magnetic refrigeration techniques based on the magnetocaloric effect (MCE) were demonstrated as a promising alternative to conventional vapour-cycle refrigeration.Recently, scientists focused their research on room temperature magnetic refrigeration.The rare earth Gd metal is regarded as a prototype for room temperature magnetic refrigerant.Considering the various requirements in application, it is necessary to search for the magnetic refrigerant possessing qualities as good as Gd but having different Tc above or below room temperature.In this article, we report the magnetic entropy changes in Gd1 -xTx(T = Ti, Cr, Fe and Cu) alloys.With a small quantity of T atoms introduced in Gd, the Curie temperature increases.The values of magnetic entropy change in these alloys are almost the same as or a little less than that of Gd.But the refrigerant capacities of these alloys are obviously larger than that of Gd.All these facts suggest that Gd1-xTx(T = Ti, Cr, Fe and Cu) alloys may be good refrigerants for room temperature magnetic refrigeration.     

Microstructures and Electrochemical Properties of Cobalt-Free LaNi4.0Al0.2Fe0.4Cu0.4-x Snx (x = 0 ～ 0.4) Electrode Alloys Prepared by Casting

The microstructure, hydriding performance, and electrochemical properties of LaNi4.0Al0.2Fe0.4Cu0.4- x Snx(x = 0 ～ 0.4) hydrogen storage alloys prepared by casting were investigated using XRD, SEM, pressure-composition isotherms, and electrochemical measurements. Substitution of Sn for Cu leads to the precipitation of LaNiSn phase. With increasing amount of tin substitution, cell volume, plateau pressures, and discharge capacities of the alloys decrease,whereas the cycle life of the alloys improves.     

聚苯胺/Co0.5Zn0.5La0.1Fe1.9O4复合材料的表征及电磁损耗

采用原位聚合法制备聚苯胺（Pani）/复合材料,使用X射线衍射仪（XRD）、扫描电子显微镜（TEM）和紫外可见吸收光谱（UV-vis）对复合材料进行了表征。XRD结果表明样品为纯Pani和Pani/Co0.5Zn0.5La0.1Fe1.9O4复合材料,SEM照片可知,纯Pani和Pani/Co0.5Zn0.5La0.1Fe1.9O4粒子的平均粒径分别约为150 nm和500 nm,UV-vis光谱表明Pani/Co0.5Zn0.5La0.1Fe1.9O4苯环上的π-π＊和n-π＊分别红移了13 nm和10 nm.在8.2-12.4GHz测试频率范围内,Pani/Co0.5Zn0.5La0.1Fe1.9O4复合材料的介电损耗角正切（tgε）在0.22-0.34之间,磁损耗正切（tgμ）在0.27-0.35之间.     

Magnetic and thermosensitive luminescent nanocomposites based on Fe3O4/SiO2/poly (N-isopropylacrylamide)/lanthanide-polyoxometalates and their controllable luminescence properties

Magnetic and temperature-responsive luminescent composites based on poly(N-isopropylacrylamide),magnetic nanoparticles and Na_9[EuW_(10)O_(36)] were fabricated. The composites were investigated by IR, UV,XRD, TGA, SEM and TEM. The prepared nanocomposites exhibit good superparamagnetic property and thermo-responsive switchable luminescence properties. The multifunctional nanocomposites can be separated by external magnetic field. Moreover, the nanocomposites exhibit an appreciable temperature response, and the red luminescence of the nanocomposites in solution can be controlled by the temperature stimuli. The hydrogel emits strong redluminescence in solution at 25 ℃,which can be seen by naked eyes. When the external temperature is 40 ℃, the red luminescence almost disappears in solution.It is expected that the multifunctional nanoparticles have potential applications in the field of biomedicine.     

Conductivity of K_(10)H_3[Dy(SiW_4Mo_7O_(39))_2] Treated by Chemistry-Heated Diffusion of Sm and Gd Permeation

Inthelastfewyears ,theapplicationsofpolyox ometalates (POMs)havereceivedmuchattention[1～ 3]fortheiruniquestructuresandproperties ,however ,thepreparationofthemareallofsolid solidorliquid liquidreactions[1] .Fromtheknowledgeoffundamen taltheory ,wethinkthatrareearthelementscanbepermeatedintoPMOsthroughthesolid gasinterfacereaction ,andtoourknowledgethiskindofexperi menthasnotbeencarriedoutuntilnow .Inthispaper ,thechemistry heateddiffusedperme ationmethod[4 ] wasusedtotreatK10 H3[Dy(SiW4 M…     

Surface Oxidation of Al2O3/SiC Nanocomposite： Phase Transformation and Microstructure

The surface oxidation behavior of pressureless sintered Al2O3/SiC nanocomposite was studied from 1000 to 1400 ℃ for more than 10 h in air. Weight gain during the process of heat treatment was measured by TG analysis. Phase transformation and microstructure changes of these specimens due to oxidation were investigated with X-ray diffraction (XRD), SEM and EDX technology. Thermogravimetric analysis show that the weight gain as a result of oxidation of SiC become significant above 1200 ℃. In the range of 1000～1300 ℃, the SiC grits are usually coated with a layer of amorphous silica after oxidation. Above 1300 ℃, the amorphous silica reacted with alumina matrix and formed mullite or crystallized into cristobalite. The rate of oxidation depends on the formation of dense cristobalite film. Large amount of needle-like mullite and alumina crystals are formed on the surface after oxidation at 1400 ℃.     

Preparation and investigation of Ce_(0.4)Zr_(0.5–x)Y_(0.1)Mn_xO_2 oxygen-storage materials

A series of Ce0.4Zr0.5-xY0.1MnxO2(0     

Preparation of Dysprosium Ferrite／Polyacrylamide Magnetic Composite Microsphere and Its Characterization

Researchofmagneticpolymermicrospherehasbeenstudiedsincethe 1970s .Themagneticpolymermicrospherecombinesthepropertyofmagneticparticlewiththatofmacromoleculeparticle .Itnotonlycanbeseparatedfromthemediumeasily ,butalsocanbesurface modifiedinorderthatthesurf…     

Crystal structure and magnetic properties of SmCo6.6Nb0.4 nanoflakes prepared by surfactant-assisted ball milling

SmCo6.6Nb0.4 nanoflakes with TbCu7 structure were successfully prepared by surfactant-assisted high energy ball milling （SA-HEBM） with heptane and oleic acid as milling medium. The microstructure, crystal structure and magnetic properties were stud- ied by scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometer, respectively. The effects of ball milling time on the c-axis crystallographic alignment and coercivity of the nanoflakes were systematically investigated. The research showed that the nanoflakes had an average thickness of 100 nm, an average diameter of 1 μm, with an aspect ratio as high as 100. As the ball milling time increased from 2 to 8 h, the reflection peaks intensity ratio I（002y/I（10l）, which indicated the degree of c-axis crystal texture of the SmCo6.6Nbo.4 phase, increased first, reached a peak at 4 h, and then decreased. Meanwhile, the coercivity of the nanoflakes also increased first, reached a peak at 13.86 kOe for 4 h, and then decreased.     

Structure and Redox Properties of VCe0.95M0.05（M=Cu,Co,Mn,Fe and Cr）Mixed Oxides

Ｖａｎａｄｉｕｍｏｘｉｄｅｈａｓｂｅｅｎｗｉｄｅｌｙｓｔｕｄｉｅｄｉｎｔｈｅｒｅｃｅｎｔｙｅａｒｓｂｅｃａｕｓｅｏｆｉｔｓｉｍｐｏｒｔａｎｃｅｉｎｍａｎｙａｒｅａｓｏｆｃｈｅｍｉｓｔｒｙ .Ｉｎｔｈｅａｒｅａｏｆｃａｔａｌｙ ｓｉｓ ,ｖａｎａｄｉｕｍｏｘｉｄｅｈａｓｂｅｅｎｕｓｅｄａｓａｃａｔａ ｌｙｓｔｆｏｒｓｅｌｅｃｔｉｖｅｏｘｉｄａｔｉｏｎ ,ｏｘｉｄａｔｉｖｅｄｅｈｙｄｒｏ ｇｅｎａｔｉｏｎ ,ａｎｄａｍｍｏｘｉｄａｔｉｏｎｒｅａｃｔｉｏｎ[1～ 4] .Ｉｎｔｈｅｏｘｉｄａｔｉｏｎｒｅａｃｔｉｏｎｏｎ…