Nd-Cu二元系合金相图

本文用X射线粉末衍射法,微差热分析法和金相显微观察,测定了Nd-Cu二元系合金相图。此合金系中共存在着五种金属间化合物,它们是:NdCu,NdCu₂,NdCu₄,NdCu₅和NdCu₆,化合物NdCu₂,NdCu₆分别在830℃,962℃同成份熔化;化合物NdCu,NdCu₄,NdCu₅,分别在602℃,853℃,916℃由包晶反应形成,有三个共晶反应,共晶点成份及其共晶反应温度分别为33at%Cu,478℃;74at%Cu,760℃;91at％Cu,874℃无论是Nd在Cu中或是Cu在Nd中都不存在可觉察到的固溶度,金属间化合物之间也不存在可觉察到的固溶度。 关键词：     

Dy-Sn二元系合金相图

本工作用X射线粉末照相法和差热分析法测定了Dy-Sn二元系合金相图。Dy-Sn系存在九个金属间化合物,其中DySn₂,Dy₅Sn₃,Dy₅Sn₄以及Dy₁₁Sn₁₀已有结构报道,其余五个化合物尚未见报道,它们是:Dy₂Sn,DySn,Dy₈Sn₉,Dy₄Sn₇和DySn₄存在四个共晶反应,六个包晶反应。化合物Dy₂Sn,DySn,Dy₄Sn₇分别在1237℃,1222℃及1154℃同成份熔化,Dy₅Sn₃,Dy₅Sn₄,Dy₁₁Sn₁₀,Dy₈Sn₉,DySn₂及DySn₄则分别在包晶反应温度,1140℃、1160℃,1175℃,1134℃,738℃以及442℃分解,富Dy区在1182℃存在一熔晶转变。DySn₄与Sn互不溶解。α-Dy中最大含Sn量大约为5wt％,β-Dy中最大含Sn量大约为7wt%。 关键词：     

Gd-Sn二元系合金相图

本文用X射线衍射和差热分析方法,对Gd-Sn二元系进行了研究,观察到三种新的金属间化合物Gd₃Sn,Gd₈Sn₇和Gd₃Sn₄,并作出了这个二元系合金相图。这个二元系中,共存在着八种金属间化合物,它们是:Gd₃Sn,Gd₅Sn₃,Gd₅Sn₄,Gd₈Sn₇,Gd₁₁Sn₁₀,Gd₃Sn₄,GdSn₂和GdSn₃。金属间化合物Gd₃Sn和Gd₅Sn₃分别在1173℃和1243℃同成分熔化;金属间化合物Gd₅Sn₄,Gd₈Sn₇,Gd₁₁Sn₁₀,Gd₃Sn₄,GdSn₂和GdSn₃分别在1179℃,1114℃,1095℃,995℃,941℃和905℃由包晶反应生成。存在着1103℃约15at％Sn,1141℃约32at％Sn和232℃约100at％Sn三个共晶反应。无论是Gd在Sn中还是Sn在Gd中都没有观察到溶解度。 关键词：     

Gd-Cu二元系合金相图

本文用X射线粉末照相法和差热分析法测定了Gd-Cu二元系合金相图,发现GdCu₆在735℃发生同素异构转变。此合金系中共存在着四种金属互化物,即GdCu,GdCu₂,GdCu₅和GdCu₆,金属互化物GdCu,在932℃同成份熔化;而GdCu,GdCu₂和GdCu₆分别在759℃,870℃和884℃由包晶反应形成,存在两个共晶反应,分别发生在32at％Cu668℃和92at％Cu875℃,无论是Gd在Cu中或是Cu在Gd中都没有可觉察的固溶度。 关键词：     

BaO-Li2O-B2O3三元系中BaB2O4-Li2B2O4和BaB2O4-Li2O截面相平衡关系的研究

本文用X射线和差热分析方法对BaO-Li₂O-B₂O₃三元系中的两个截面:BaB₂O₄-Li₂B₂O₄和BaB₂O₄-Li₂O作了研究。在BaB₂O₄-Li₂B₂O₄赝二元系中发现了一个新的化合物4BaB₂O₄·Li₂B₂O₄。化合物在930±3℃由包晶反应形成,并与Li₂B₂O₄形成共晶反应。共晶温度为797±3℃,共晶点组分为79mol％Li₂B₂O₄。在BaB₂O₄-Li₂O截面中也存在化合物4BaB₂O₄·Li₂B₂O₄,其包晶反应温度从930±3℃随Li₂O含量增加下降到908±3℃。在组分60mol％Li₂O处形成另一个新的化合物2BaB₂O₄·3Li₂O。该化合物在630±3℃也是由包晶反应形成,并与Li₂O和Li₂CO₃分别形成共晶反应,共晶温度分别为400±3℃和612±3℃。在BaB₂O₄-Li₂B₂O₄和BaB₂O₄-Li₂O体系中都没有观察到固溶体。用计算机程序分别对化合物4BaB₂O₄·Li₂B₂O₄和2BaB₂O₄·3Li₂O的X射线粉末衍射图案进行了指标化,其结果:4BaB₂O₄·Li₂B₂O₄的空间群为Pmma,a=13.033?,b=14.630?,c=4.247?,每个单胞包含两个化合式单位;2BaB₂O₄·3Li₂O的空间群为Pmmm,a=4.814?,b=9.897?,c=11.523?,每个单胞也含有两个化合式单位。 关键词：     

Sm-Ni二元系合金相图

本文用X射线衍射、差热分析及金相分析方法测定了Sm-Ni二元系合金相图。在此二元系中观察到8个金属间化合物:Sm₃Ni(664℃分解),SmNi(熔点为1079℃),SmNi₂(1034℃分解),SmNi₃(1135℃分解),Sm₂Ni₇(1220℃分解),SmNi₄(1282℃分解),SmNi₅(熔点为1430℃)和Sm₂Ni₁₇(1288℃分解)。发生三个共晶反应:Sm₃Ni-SmNi(570℃,～32at%Ni),SmNi-SmNi₂(809℃,53.5at%Ni)和Sm₂Ni₁₇-Ni(1280℃,94at%Ni)。无论是Sm在Ni中或是Ni在Sm中,均未观察到明显的固溶度。 关键词：     

Dy-Ni二元系合金相图

木文用X射线粉末衍射法配合差热分析法,确证了金属间化合物DyNi₄的存在,发现了一种新的金属间化合物Dy₄Ni₁₇,并作出了这个二元系合金相图。此合金系中共存在着十种金属间化合物,它们是:Dy₃Ni,Dy₃Ni₂,DyNi,DyNi₂,DyNi₃,Dy₂Ni₇,DyNi_{4关键词：}     

Nd-Ni二元系合金相图

本文用X射线衍射和差热分析方法测定了Nd-Ni二元系合金相图。在此二元系中观察到如下八个金属间化合物:Nd₃Ni(熔点为590℃),Nd₇Ni₃(熔点为616℃),NdNi(熔点为780℃),NdNi₂(940℃分解),NdNi₃(1030℃分解),Nd₂Ni,(1234℃分解),NdNi₅(熔点为1420℃)和Nd₂Ni _关键词：     

LiIO3-NaIO3赝二元系相图及其非晶态晶化动力学的研究

本文对LiIOO₃-NaIO₃赝二元系的相图,相变,非晶态的形成和稳定性,以及晶化的动力学过程等进行了仔细的研究,LiIO₃-NaIO₃赝二元系属共晶体系,共晶温度为325℃,共晶点成份为含50m/o LiIO₃,用共晶点附近成份的试样,在超过熔点150℃的情况下首次获得碘酸盐的非晶态,非晶态的存在降低了LiIO₃的表观相变温度,强X射线的辐照,各种空气湿度,细粒度等因素都加 关键词：     

Co-Ga二元系的X射线研究

本文主要用X射线粉末衍射法,配合着差热分析,研究了Co-Ga二元系的平衡关系。这个系统在室温除Ga与γ-Co外,存在着α′,β和φ三个相。α′相是以面心立方为基的超结构相,可以看作是Ga溶于α-Co中,而使α-Co得在常温稳定存在的相。α′相在室温的均匀范围为2.4—10.7at.％Ga。β相于1177℃由α′+Lβ包晶反应所形成,是CsCI型结构,在常温的均匀范围为36.3—59.8at.％Ga。单相区内点阵常数随成份的变迁在47.5at.％Ga处有一最大值,这与Al-Ni二元系中的β相很相似,在这个最大值左边的富Co区域是替代式固溶体,而在最大值右边的富Ga区域,则是缺陷式固溶体。ψ相的均匀范围很窄,仅存在于75at.％Ga附近。它属于四方晶系,空间群为D_4h¹⁴-P4₂/mnm,晶胞内含4个化合式量CoGa₃,在20℃和75.4at.％Ga处的点阵常数为:a=6.2365?,c=6.4347?,c/a=1.0318。它是由包晶反应β+L←→ψ所形成的,反应温度为833℃。无论Ga在γ-Co中,或Co在Ga中都不存在可以观察得到的固溶度。从CoGa₃到Ga,存在着一条27℃的共晶等温线,共晶点非常接近纯Ga。 关键词：     

Magnetocaloric effect in DyCu2

The magnetocaloric effect of the rare-earth intermetallic compound DyCu₂ is explored through magnetization measurements. DyCu₂ is paramagnetic at the room temperature but becomes antiferromagnetic below 27 K (Neel temperature). Strong temperature and field dependence of magnetization in DyCu₂ at and around the Neel temperature lead to a large magnetocaloric effect. An appreciable magnetocaloric effect persists well above the Neel temperature probably because of the presence of short-range ferromagnetic correlations in the paramagnetic state of DyCu₂. This along with the absence of magnetic hysteresis lead to a large effective refrigerant capacity of 194 J/kg below 44 K, which makes the material important as a potential magnetic refrigerant for the cryogenic liquefier cycles.     

Effect of γ-radiation on TL,ESR and evaluation of trapping parameters of K2Ca(SO4)2:X (X = Dy or Eu) phosphors

ABSTRACT

The present phosphor K₂Ca(SO₄)_2, doped by dysprosium and europium, is synthesized by the solid-state diffusion method. The doping concentration varied from 0.1 to 0.5?mol% by weight. A phosphor is studied for X-ray powder diffraction, surface morphology analytical scanning electron microscopy and analyzed by energy-dispersive X-ray spectroscopy. The prepared phosphor K₂Ca(SO₄)_2, doped by Dy and Eu, has been characterized for thermoluminescence (TL) glow curve, showing maximum peak temperatures at 176°C and at 200°C, respectively. TL peak intensity of K₂Ca(SO₄)₂: Dy and Eu was compared with the standard TLD CaSO₄:Dy phosphor. Both phosphors show the dose linearity ranging from 20 to 240?Gy doses of γ-rays of ⁶⁰Co source at room temperature. Negligible fading has been observed when irradiated with γ-rays and stored for 60 days without taking any care from sunlight. The TL materials were used in powder forms. The linearity of ESR response with dose for powder forms of K₂Ca(SO₄)₂: Dy was also studied using the signals at g?=?2:0039 (SO₃^?) and at g?=?2:02282 (SO₄^?). It was observed that the range of linearity of dose response extended between 20 and 240?Gy. Kinetic parameters have been calculated using three different methods: Chen's peak shape method, various heating rate method and initial rise method. To study the heating rate method, the glow curve was recorded for the heating rate as 1°C, 3°C, 5°C, 7°C, 9°C each time. Electron spin resonance (ESR) shows the ionic radical formation during γ-irradiation, which is responsible for TL. The effect of temperature and microwave power on the ESR signal was also studied.     

Thermoluminescence of γ-irradiated BaCa(SO4)2:Eu,Dy

In this paper, thermoluminescence (TL) studies of BaCa(SO₄)₂:Eu,Dy phosphor are reported. A microcrystalline sample of BaCa(SO₄)₂:Eu,Dy was prepared by a solid state diffusion method and the formation of the compound was confirmed by the X-ray diffraction study. Morphology of the phosphor was analyzed by scanning electron microscopy (SEM). The sample is found to have an average particle size of 5?µm. TL glow curves of the γ-irradiated samples with different concentrations of Eu and Dy were studied and compared with BaCa(SO₄)₂:Eu and BaCa(SO₄)₂:Dy. It has been found that a single peak was located at around 230°C with the highest TL intensity in BaCa(SO₄)₂:Eu,Dy which is eight times and two times more than singly Dy- and Eu-doped BaCa(SO₄)₂ phosphor, respectively. For TL analysis, BaCa(SO₄)₂:Eu,Dy (0.2?mol%, 1?mol%) is annealed at different temperatures ranging from 900°C to 1100°C. Analysis of the TL glow curve was carried out by a glow curve deconvoluted method. Trapping parameters (activation energy and frequency factor) of all TL glow curves were evaluated by Chen's peak shape method. A comparison of trapping parameters between BaCa(SO₄)₂:Eu,Dy; BaCa(SO₄)₂:Eu and BaCa(SO₄)₂:Dy phosphors at 900°C, 1000°C and 1100°C is also reported in this paper.     

Formation of the Cu6Sn5 Intermetallics in Cu/Sn Thin Films

Physics of the Solid State - The formation of the Cu6Sn5 intermetallic in Sn(55nm)/Cu(30nm) thin-film bilayers has been studied upon heating the film sample from room temperature to 300°C...     

Mn-Ga二元系的X射线研究

本文从44个缓冷和淬炼Mn-Ga合金摄取了德拜·谢乐照相,并配合了在富Ga部分的差热分析,初步画出了这个系统的相图。这个系统除纯Ga外共有十个相。Mn在Ga中的固溶度是几乎无可觉察的。α相是Ga在α-Mn中的原固溶体,在室温的固溶度为1.95at％Ga。β相在室温的均匀范围为8.6—19.2at％Ga,这是β-Mn结构,因此可看作是β-Mn的固溶体,由于Ga原子无规地替代了部分Mn原子而这个结构得在室温稳定存在。γ相可分成γ₁,γ₂,γ₃,三部分,γ₁是面心立方结构,γ₂是面心四方结构,γ₃是有序的面心四方结构,与Cu-Au系中的CuAuⅠ同型。在室温下稳定的是γ₃,均匀范围为37—45at％Ga,而在高温稳定的却总是γ₁。从γ₁变到γ₂,再从γ₂变到γ₃的变化是二级相变。有序度随Ga含量的递增而递增,随温度的递升而递降。整个γ相可看作是γ-Mn的固溶体,γ-Mn本身是不可能用淬炼的办法在室温获得的。δ相只存在于高温,可看作是δ-Mn的固溶体。由于Ga原子替代了部分Mn原子,因而δ一Mn结构产生了畸变而有序化。ε相是有序的六角密堆积结构,每个晶胞含8个原子,它是在约820℃从γ相同成份地转变而成的,在室温的均匀范围估计为27一30at％Ga。η相在室温约50—60at％Ga处有一宽广的均匀范围。从520到600℃,它经历一多型性变化,转变为λ相。λ相的相区随温度的递升而向富Mn的一边偏移。η和λ结构都很复杂。在富Ga的一边,存在着三个居间相χ,φ和ω,它们是由包析或包晶反应所形成的。ω相的化合式很可能相当于Mn₂Ga₉或MnGa₅,而φ相则与NiHg₄同型,在Mn_2.3Ga_7.7左右有一狭隘的均匀范围。在室温稳定存在的七个居间相中,β,ε,γ₃,X和φ是铁磁性的。铁磁性最强的是Ga含量较富的γ₃和φ相。我们测量了其中若干合金的饱和磁化强度与居里温度。 关键词：     

Structural,dielectric, electrical and piezoelectric properties of Ba<Subscript>4</Subscript>SrRTi<Subscript>3</Subscript>V<Subscript>7</Subscript>O<Subscript>30</Subscript> (R=Sm,Dy) ceramics

Polycrystalline samples of Ba₄SrRTi₃V₇O₃₀ (R=Sm and Dy), members of the tungsten-bronze family, were prepared using a high-temperature, solid-state reaction technique and studied their electrical properties (using complex impedance spectroscopy) in a wide range of temperature (31–500°C) and frequency (1 kHz-1 MHz). Preliminary structural (XRD) analyses of these compounds show the formation of single-phase, orthorhombic structures at room temperature. The scanning electron micrographs (SEM) provided information on the quality of the samples and uniform distribution of grains over the entire surface of the samples. Detailed studies of the dielectric properties suggest that they have undergone ferroelectric-paraelectric phase transition well above the room temperatures (i.e., 432 and 355°C for R= Sm and Dy, respectively, at frequency 100 kHz). Measurements of electrical conductivity (ac and dc) as a function of temperature suggest that the compounds have semiconducting properties much above the room temperature, with negative temperature coefficient of resistance (NTCR) behavior. The existence of ferroelectricity in these compounds was confirmed from a polarization study.