Effect Of Ga Addition Research Articles

Defect-induced structural disorder in tetragonalCu(In1−xGax)5Se8 thin films investigated by Raman spectroscopy: the effect of Ga addition

The dependence of the phonon frequencies of the quaternaryCu(In1−xGax)5Se8 films with tetragonal structure on the Ga content have beensystematically investigated by means of Raman scattering. The dominantA1 modeshifts from 151 cm−1 for CuIn5Se8 to 160 cm−1 for CuGa5Se8 in an approximately polynomial but not linear curve, because different typesof local tetrahedral cationic clusters around Se distribute in the defectcrystal structures. The vibrational modes in the low-frequency region below125 cm−1 clearly show one-mode behaviour, whereas significant changes in the frequency range from 160 to235 cm−1 indicate defect-induced structural disorder and show two-mode behaviourdue to Ga addition. Additionally, the quenching of the Raman band at174 cm−1 for the Ga-rich films reveals that this mode should most probably originatefrom other similar localized structure phases in chalcopyrite-relatedCuIn5Se8 butnot CuGa5Se8, due to the Ga inhibition effect. Such results should be ascribed to asymmetric distributionof Ga and In on a microscopic scale, resulting in the different properties of bonds betweenlocal clusters.

Effect of Ga addition on the glass-forming ability of Fe-based bulk glassy alloy

It has been clarified that Fe Al Ga P C B bulk glassy alloy exhibits high glass-forming ability and good soft magnetic properties [1–3]. Recently, we have developed a number of Fe-based bulk glassy alloys with high glass-forming ability in Fe (Cr, Mo) Ga P C B and Fe Co Ga P C B systems [4–6]. Furthermore, with the aim of increasing saturation magnetization (Is), we also developed Fe Ga P C B and Fe Ga P C B Si bulk glassy alloys in which the content of Fe is higher than the above-described alloys [7–9]. These bulk glassy alloys with diameters of 1 to 2.5 mm can be easily prepared by copper mold casting and exhibit high Is of 1.3 to 1.4 T. Here, it is noticed that Ga is a common element in all these alloys. This paper intends to investigate the reason why the addition of Ga to Fe P C B alloys is effective in enhancing glass-forming ability. Multi-component Fe80P13C7, (Fe0.8P0.13C0.07)95Ga5, [(Fe0.8P0.13C0.07)0.95Ga0.05]95B5 and Fe80−x Gax P12C4B4 alloys were examined in the present study. The ingots were prepared by induction melting a mixture of pure Fe and Ga metals, prealloyed Fe-C and Fe-P ingots, and pure B crystal in a purfied argon atmosphere, respectively. Their compositions are nominally expressed in atomic percentage. From the master alloy ingot, a ribbon with a cross section of about 0.020 × 1.0 mm2 was prepared by melt spinning. The amorphicity of the ribbons was examined by X-ray diffractometry with Cu-Kα. The specific heat associated with glass transition, supercooled liquid region and crystallization was measured at a heating rate of 0.67 K/s with a differential scanning calorimeter (DSC). The liquidus temperature (T1) of alloys was measured by cooling the molten alloy samples at a rate of 0.033 K/s with a differential thermal analyzer (DTA). It was confirmed by X-ray diffraction that the present melt-spun Fe80−x Gax P12C4B4 alloy ribbons were composed of an amorphous phase without any crystallinity over the whole composition range up to 10 at.% Ga. Fig. 1 shows the DSC curves of Fe80−x Gax P12C4B4 (x = 0 to 10 at.%) glassy alloys. All the glassy alloys exhibit a glass transition and a supercooled liquid region prior to crystallization. The supercooled liquid region, defined as the difference between the glass transition temperature (Tg) and the onset temperature of crystallization (Tx), Tx (=Tx − Tg), increases into the range of 25 to 37 K with increasing Ga content from 1 to 5 at.%, accompanying an increase in Tg and Tx. A distinct supercooled liquid state with full structural relaxation is observed for the 5 at.% Ga alloy. It is clearly seen that the supercooled liquid region in an internal equilibrium state is retained over a temperature interval of 20 K. The further increase in Ga content to 10 at.% causes a decrease in Tx and the largest Tx of 37 K is obtained for the 5 at.% Ga alloy. Fig. 2 shows the DSC curves of the Fe80P13C7, (Fe0.8P0.13C0.07)95Ga5 and [(Fe0.8P0.13C0.07)0.95Ga0.05]95B5 glassy alloys. The Fe80P13C7 alloy is a typical amorphous ferromagenetic alloy with good soft magnetic properties developed in 1974 [10]. As shown in the figure, there is no distinct supercooled liquid state with full structural relaxation for Fe80P13C7

Improvement of coercivity of anisotropic Nd–Fe–B HDDR powders by Ga addition

The effect of Ga addition on the increase of coercivity of HDDR-treated Nd–Fe–B powders was investigated. The Ga addition suppresses grain growth and may decrease the region where magnetocrystalline anisotropy is reduced. In addition, a heat treatment in which the hydrogen pressure was decreased in steps during the recombination reaction resulted in good magnetic properties of B r=1.44 T, j H c=0.97 MA m −1 and ( BH) max=308 kJ m −3.

Effects of Ga addition on the mechanical properties of 35Ag-30Pd-20Au-15Cu alloy.

Ten 35Ag-30Pd-20Au-15Cu alloys containing 0.00, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 2.00, 4.00, or 6.00% Ga were experimentally prepared to investigate the effect of Ga on their mechanical properties in addition to their use for denture frameworks, connectors and clasps. The effect of Ga addition on the mechanical properties was marked with a significant increase in the tensile strength, 0.2% off-set proof stress (proof stress) and Vickers hardness observed at low Ga contents (0.25-2.00%). On the other hand, the elongation significantly decreased with the addition of Ga at all contents used in this study. The tensile strength, proof stress and Vickers hardness of the 35Ag-30Pd-20Au-15Cu alloys containing 0.25-2.00% Ga were in the range of 809-957 MPa, 669-857 MPa and 260-301 MPa, respectively. These values are similar to those of Co-Cr alloys, suggesting that 0.25-2.00% Ga alloys can be used for denture frameworks, clasps and connectors.

P‐52: Luminescence Properties of Pr‐Doped Perovskite Titanate Phosphors

AbstractWe presented luminescence properties of various perovskite titanate phosphors like ATiO3:Pr3+ (A = Ca, Sr, Ba, Ca1−xBax, Sr1−xBax). Especially, the effect of Ga addition on the luminescence properties was of our interest. Without the Ga addition, the SrTiO3:Pr3+ and BaTiO3:Pr3+ rarely showed red luminance, while the CaTiO3:Pr3+ phosphor had very intense red luminescence at low concentration of Pr. The Ga addition caused the luminescence enhancement for all of the above perovskite titanate phosphors, especially, the SrTiO3:Pr3+ showed the most outstanding enhancement. Also, we investigated the effects of the change of the A‐site in the perovskite phase, ATiO3. While the partial replacement of Ca with Ba led the lumincescence to decrease, the partial substitution of Sr with Ba of 20 mole % led the luminescence to increase about 2 times.

Ｇａ添加Ｎｄ‐Ｆｅ‐Ｂ系ＨＤＤＲ磁石粉末の磁気特性

The effect of Ga addition on the enhancement of coercivity in HDDR-treated Nd-Fe-B powders, was investigated. Microstructural observation revealed that Ga addition suppresses grain growth of recombined Nd2Fe14B during the DR process. Analysis using the microstructural parameters in Kronmmarüllers equation shows that the α K value of Ga-added samples (0.48) is larger than that of ternary samples (0.12), which suggests that Ga leads to the development of reduced surface anisotropy in the recombined Nd2Fe14B grains.

Effect of Ga-Addition on the Glass-Forming Ability and Superconducting Properties of Bi-Sr-Ca-Cu-O System

The effect of the addition of Ga2O3, a conditional glass former, on the glass-forming ability and superconducting properties of samples with Bi2-xGaxSr2Ca2Cu3Oy (x=0-1.5) compositions has been investigated. The quantity Tx-Tg increases from 54 to 68K, indicating an improvement in the glass forming ability of the samples, where Tg and Tx are glass transition and crystallization temperatures, respectively. The superconducting properties deteriorate due to the migration of Ga ions into the 2212 phase: the superconducting critical temperature of the 2212 phase decreases from 85K for Ga-free sample to 72K for the sample with x=0.5, and the sample with x=1.5 shows semiconducting properties. The c-axis length of the 2212 phase decreases from 3.081nm for Ga-free sample to 3.074nm for the sample with x=0.5, but a-and b-axis lengths remain constant. A new Ga-compound formed in Ga-added samples was identified to be GaSr0.55Ca1.05Cu0.5Ox. Superconducting phases of the Ga-based system are not formed even in Ga-rich samples.

The effects of Ga addition on the structure and agnetic properties of Nd 2Fe 14B compounds

The effects of Ga substitution on the structure and magnetic properties of Nd 2Fe 14B systems have been studied. The crystalline constant c increases with increasing Ga content while a keeps almost constant. The saturation magnetization and spin reorientation temperature decrease with increasing Ga content. However, the replacement of Fe by Ga leads to a rise in Curie temperature which is related by competition between exchange interaction of the preferential substitution of Ga into 8 j 1 and 4 c . A small amount of Ga addition also leads to an increase in the anisotropy field.

Ｇａ添加Ｎｄ‐Ｆｅ‐Ｂ磁石

The effect of 20 kinds of additional elements have been studied to increase the intrinsic coercivity for Co substituted Nd-Fe-B sintered magnets. The addition of Ga was found to increase iHc more than any other elements.The effects of Ga addition on magnetic properties and thermal stability were investigated for Nd (Fe0.72Co0.2B0.08)5.6 and Nd0.8Dy0.2 (Fe0.86Co0.06B0.08)0.5 magnets. A combination of both Ga and Nb or Ga and W additions improved thermal stability which was attributed to the increase of iHc and good squareness by finer grains.Typical Ga added 2 sintered magnets and their magnetic properties and exposure temperatures to keep the irreversible losses under 5% (Pc=2) were as follows.[1] Nd(Fe0.7Co0.2B0.08Ga0.02)5.6: Br=12.2 KG, iHc=16.5 KOe and (BH)max=35.2 MGOe/140°C[2] Nd0.8Dy0.2(Fe0.835CO0.06B0.08Nb0.015Ga0.01)5.5: Br=10.45 KG, iHc=27.1 KOe and (BH)max=26.2 MGOe/260°C