Increasing Ga Content Research Articles

First-order magnetization process and spin phase diagram of Nd2Fe14-xGa xB and Nd2Fe11.5-xCo2.5GaxB.

The first-order-magnetization-process (FOMP) transition field, Curie temperature, and spin-reorientation temperature of Nd{sub 2}Fe{sub 14{minus}{ital x}}Ga{sub {ital x}}B and Nd{sub 2}Fe{sub 11.5{minus}{ital x}}Co{sub 2.5}Ga{sub {ital x}}B with {ital x}{le}1.5 have been determined. Ga increases the Curie temperature of Nd{sub 2}Fe{sub 14{minus}{ital x}}Ga{sub {ital x}}B but decreases that of Nd{sub 2}Fe{sub 11.5{minus}{ital x}}Co{sub 2.5}Ga{sub {ital x}}B compounds. This difference in the behavior of Ga stems from the preferential occupancy of Fe sites being different in the above two compound series. The spin-reorientation temperature of these compounds decreased with increasing Ga content. The FOMP transition field changed in an opposite manner. At a fixed temperature (180 K), it increased with increase in Ga content. The lower the temperature, the more pronounced the increase of the FOMP transition field {ital B}{sub tr}. Based on these findings, spin phase diagrams were constructed.

Magnetic properties of Ga doped NdFeCoB sintered magnets

The magnetic properties of Nd/sub 16/Fe/sub 77/B/sub 7/ and Nd/sub 16/Fe/sub (61-x)/Co/sub 16/Ga/sub x/B/sub 7/ (x=0, 1, 2, 4, 7) have been measured. It was found that the remanent magnetization (B/sub r/), the maximum energy product (BH)/sub max/, and the Curie temperature (T/sub C/) decrease with increasing Ga content. The coercive field (H/sub c/) increases with increasing Ga content when x is smaller than 2, but decreases when x>2. At x=2, the coercive field reaches its maximum value. It was also found in all the samples investigated that there is a linear relationship between H/sub c//sup 1/2/ and T/sup 2/3/, which cannot be explained by Gaunt's wall-barrier model. The temperature dependence of the calculated values of H/sub 0/ and (4bf) is examined.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Gibberellin Inhibits Fruit Abscission Following Seed Abortion in Peach

Seed coats of developing fruit of peach [Prunus persica (L.) Batsch cvs. Redkist, Redskin, and Loring] were punctured at 31, 33, and 38 days after full bloom (DAFB), respectively. Injections of water, 390 mg GA3/liter, or 390 mg GA4+7/liter were made immediately following seed puncture. Seed puncture and water injection following puncture resulted in abscission of all fruit. Injection of GA3 and GA4+7 delayed abscission of `Redkist' and `Redskin' fruits of punctured seeds by 6 to 10 days. Both GA treatments resulted in normal growth into Stage II and increased fruit retention through Stage III in `Loring'. About 100 μl of 250, 500, or 1000 mg GA3/liter was injected into the locule of `Loring' fruits following seed puncture at 30, 40, or 50 DAFB. GA treatments at 30 DAFB resulted in≈ 75% fruit set in comparison to seeded control fruit, while fruit treated at 40 and 50 DAFB abscised by the end of Stage II. Increasing GA concentration from 250 to 1000 mg·liter-1 had no additional effect. Movement of the GA was examined by injecting 3H-GA1 into the locule following the puncture treatment. More than 97% remained in the fruit after 96 hours. The percentage of 3H recovered in the seed cavity decreased over time, whereas recovered label increased in both endocarp and mesocarp. The results suggest a potential regulatory role for seed-produced gibberellins during early Stage I of development. We have identified an apparent change in tissue sensitivity to gibberellin induction of seedless fruit development between 30 and 40 DAFB in `Loring' peach.

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.

Investigation of Ga Diffusion in (001) and (111) CdTe Layers Grown on (001) GaAs

ABSTRACTA secondary ion mass spectroscopy study of Ga diffusion in CdTe grown on (001) GaAs was carried out. The layers were grown by pulsed laser evaporation and epitaxy. Two characteristic regions with increased Ga concentration were found. The first was the CdTe/GaAs interface where the concentration of Ga decreases rapidly to the detection limit of −8 × 1014 cm−3. This region was usually less than 300 nm wide. The second was a surface region with a Ga accumulation of up to −1017 cm−3. Ion imaging revealed that in the (001) CdTe layers, Ga accumulates near the surface at localized spots, up to about 8 μm in diameter. This feature is less apparent in the (111) CdTe layers. Annealing at 500 °C for 1 h increased the Ga concentration in the whole layer to above 1016 cm−3. We also observe thermal annealing induced precipitation of Ga at the surface of bulk CdTe samples which were originally uniformly doped with Ga.

Electronic properties of Ga-doped amorphous silicon

We have prepared Ga-doped a-Si films by PECVD, by the addition of metalorganic Ga compounds to the silane. We give here a first account on electrical, optical and structural properties. The samples were prepared with the deposition parameters within the usual range. With increasing Ga content the room temperature dark conductivity of a-Si first drops to the value of 8×10 −12 Ω −1 cm −1 which is typical for compensated a-Si and then raises similar to the boron doping case. There is, however, an important difference: Since Ga is a metal, metallic conductivity can be attained at large Ga concentration.

Crystallization Properties and Operative Regions of Erasable Optical Disk using Chalcogenide Films

Measurements of the index n and the activation energy E in the Avrami equation from the reflectivity change and DSC enable us to discuss the crystallization properties of chalcogenide films and the operative regions of the erasable optical disk. The reasonable optical disk material is necessary to have the high melting temperature Tm and the larger activation energy E of crystallization. In order to increase Tm and E, it is desirable that, in the Ga-Se-Te systems, the increase of Ga content is necessary.

Origin of the B&amp;lt;inf&amp;gt;c2&amp;lt;/inf&amp;gt;enhancement in ternary Nb-Sn phases

Nb-Sn-Ga alloys were chosen as a model system in order to investigate the influence of third element additions on the normal and superconducting properties of alloyed Nb 3 Sn phases. With respect to compositions formed by the bronze process (with Ga added to the Cu Sn matrix) alloys with concentrations close to the Sn-rich side of the A15 phase boundary were prepared. The analyses based on the GLAG theory shows that inspite of a decrease in the density of states at the Fermi level with increasing Ga content the upper critical field, B c2 , is increased due to a large enhancement of the residual resistivity. However, Ga destabilizes the stoichiometric composition of the A15 phase and the critical temperature decreases for higher Ga contents. Therefore, B c2 maximized at 1 to 1.5at% Ga for reaction temperatures at 700°C. High critical fields up to 31.5 T (at T = 4.2K) have been achieved for higher reaction temperatures, which shift the phase boundary of the A15 phase field towards stoichiometry.

Electronic properties of Mg0.7Zn0.3-xGaxsimple metallic glasses

Measurements of the Hall coefficient, the angular correlation of the positron annihilation, the low-temperature specific heat, and the electrical resistivity are reported for the simple metallic glasses Mg0.7Zn0.3-xGax in the composition range 0<or=x<or=0.2. The Hall coefficient is negative and temperature independent between 78 and 300K. It becomes more negative with increasing Ga concentration, indicating the decrease in the carrier density. This is in contradiction to the free-electron prediction. The one-dimensional Fourier transform of the angular correlation curve for the Mg0.7Zn0.24Ga0.06 alloy also indicates a deviation from the free-electron curve. The electronic specific heat coefficient decreases slightly with increasing Ga content, again being opposite to the trend expected from the free-electron model. All these results are consistent with the departure from the free-electron behaviour when Ga is added to the free-electron-like Mg0.7Zn0.3. The electrical resistivity at 300K, rho 300K, increases from 54 to 94 mu Omega cm when Ga is substituted for Zn up to x=0.2. It is also found that the detailed temperature dependence of the electrical resistivity at low temperatures depends strongly on the magnitude of rho 300K. The electrical resistivity data above 300K, in combination with X-ray diffraction studies, revealed that the addition of Ga changes the crystallisation process drastically and contributes to suppress the formation of the metastable Mg51Zn20 compound.

Physico-chemical properties of glycyrrhizic acid in aqueous media. IV. Emulsification of oleic acid

Emulsions of a relatively small amount of oleic acid in aqueous glycyrrhizin (GA) solution were investigated by means of turbidity measurement. Oleic acid was easily emulsified in aqueous GA solution by shaking with a reciprocating shaker to give stable o/w emulsions. With increasing GA concentration at a constant pH and ionic strength, the turbidity of emulsion initially increased and then decreased at GA concentrations above its critical micelle concentration. This effect may by attributed to the solubilization of oleic acid by GA solution. The emulsifying power of GA, which was defined as the change of turbidity per unit volume of oleic acid emulsified, was enhanced with rising pH and decreasing ionic strength of GA solution. The dissociation of both GA and oleic acid was considered to play an important role in the emulsification of the system.

Expansion of the Laves phase TiBe 2 by addition of gallium with anomalous results

Substitution of gallium for part of the beryllium in the Laves phase TiBe 2 forms a stable cubic C15 phase over the general composition range TiBe 2-xGa x where 0 ≤ × ≤ resulting in a linear expansion of the lattice from aino = 6.4532 rA for the TiBe 2 to an a o = 6.596 Å for the limiting composition. No ferromagnetic transition is observed for measurements to 2.1 K. Low-temperature specific heat data show that the temperature-dependent T 3lnT/T SF term, related to spin fluctuations, decreases with increasing Ga content. This decrease is shown to be due to a decrease in the density of electronic states at the Fermi energy rather than a decrease in the spin fluctuation temperature.

Nuclear magnetic resonance in liquid InGa alloys

AbstractMeasurements of the Knight shift of 115In and 71Ga in liquid InGa bulk samples are carried out as a function of temperature from 263 to 523 K and concentration from 0 to 100 at% Ga. It is shown that bulk and particle samples give, within the experimental error, the same Knight shift values. The results are compared with contradictory experimental data in the literature, and it is found that they agree with those of one of the earlier authors. A further important result based on these measurements extended over a broad temperature range is the determination of the temperature coefficient of the Knight shift of both isotopes 115In and 71Ga as a function of concentration. The 115In temperature coefficient decreases with increasing Ga concentration whereas the 71Ga one remains almost constant over the entire concentration range. Comparisons between the experimental and the theoretical results show satisfactory agreement in some cases but strong discrepancies in others.

Neutron irradiation and annealing studies of V 3Ga

Studies of the effect of fast neutron irradiation ( E > 1 MeV, at 60°C) on the superconducting properties of V 3Ga of compositions spanning the A15 phase field have shown that V 3Ga exhibits an increasing susceptibility to damage with increasing Ga concentration. Annealing studies have shown that recovery from neutron damage occurs in two temperature ranges. Activation energies are estimated for these processes which are correlated with an unusual recovery of the lattice parameter. A simplified vacancy interstitial mechanism is proposed which could account for these results.

Ag-Ga合金の内部酸化について

The solid solution of silver containing 0.42∼2.09 at%Ga was cold-worked and internally oxidized at temperatures between 500 and 650°C in still air for viarious times. The effects of oxidation temperature, time and solute content on the growth of the internally oxidized layer were investigated. The product of the solubility N0(s) and the diffusivity D0 of oxygen, and the activation energy for N0(s)D0 were calculated by Wagner’s equation.The results were summarized as follows.(1) The relation between the depth of the oxidation zone and the oxidation time can be expressed by a parabolic law. It was concluded that internal oxidation was governed by the diffusion of oxygen through the internally oxidized layer.(2) The activation energy for the product N0(s)D0 determined from the internal oxidation of the cold-worked Ag-0.42 at%Ga alloy below 550°C and above 600°C was 19.8±0.5 kcal/mol and 22.4±0.4 kcal/mol, respectively. The activation energy for internal oxidation of alloys except 0.42 at%Ga alloy was 23.3∼25.0 kcal/mol and slightly increased with increasing Ga content.(3) The product N0(s)D0 of oxygen in pure silver obtained by extrapolating Ga content to NGa(0)=0 was given by (13.5±0.4)×10−5exp[(−23400±600)⁄RT]. This value is in agreement with the product of the values of N0(s) and D0 determined individually by Eichenauer and Müller.

Reduction of apple skin russeting by gibberellin A4+7

SummaryFoliar sprays of a mixture of the gibberellins A4 and A, applied at or near petalfall resulted in less skin russet on Jonathan and Golden Delicious apples at harvest. Russet level declined with each increase in GA concentration from 25 to 200 ppm. In contrast, benzyladenine (BA) sprays when applied at the same time at 50 or 150 ppm increased the level of skin russet at harvest.Both materials stimulated parthenocarpy, and mean seed number per fruit at harvest declined with increasing concentration of either GA or BA. With Jonathan, GA application tended to give rise to less broad, more elongated fruit at harvest compared with the control, but BA had the opposite effect.

Axial ratio changes in ternary f.c.t. phase alloys of the In-Ga-Tl system

The lattice parameters and the axial ratio of disordered f.c.t. In-rich alloys in the ternary system of In-Ga-Tl are measured by the X-ray powder method. The results show that the axial ratio remains constant with increasing Ga content along lines of constant Tl concentration, while it decreases appreciably with increasing Tl content along lines of constant Ga concentration. These trends are qualitatively interpreted in terms of the relation of the first few reciprocal lattice vectors to the first zero position in the mean pseudopotential of the alloy (the “ q 0-effect”).

Experimental Studies on Plant Metabolism

AbstractTreatment of Ricinus communis seeds with GA accelerated the production of reducing sugars and increased the total carbohydrate content. The effect increased progressively with increasing concentration of GA. — GA treatment also induced an earlier appearance of starch which was shown to be completely absent at the early stages of germination. Furthermore, GA accelerated the conversion of oils into carbohydrates. — Analysis of germinating seeds for their nitrogen content showed that whenever an increase in soluble‐N due to GA treatment was detected, there was a decrease in protein‐N. Breakdown of protein and formation of soluble‐N increased progressively with increase in GA concentration. — GA induced variable changes in the length of the radicles and the hypocotyls, the dry weight and the water content of germinating seeds.

Elastic wave propagation in the group vb semimetals

The present study reports the evolution of microstructure and magnetic properties of Cu2MnAl1−xGax Heusler alloys. The L21 phase, which remained stable up to a Ga substitution of x = 0.3, transformed into mixed phases, i.e., hexagonal close packed (HCP) and complex cubic structure (CCS) on further addition of Ga. The non-monotonic increase in the lattice constant indicates that some amount of Ga retains its monovalent state. The magnetic phase showed a transition from ferromagnetic to paramagnetic state with increasing Ga concentration. The re-entrant temperature (TR) decreased from 8.2 K to 5.2 K as Ga content increased from 5 at% to 10 at%. The strength of magnetic exchange-coupling also reduced with an increase in Ga content. Gaussian process regression (GPR) was used to estimate the lattice parameter using the ionic radii and Pauling electronegativity of the constituents. The modeling approach showed high accuracy and stability, providing new insights into future alloy development.

Zustandsdiagramm und eigenschaften von Gallium-Zinn-Legierungen

By thermal analysis and X-ray and dilatometric measurements the equilibrium conditions in the complete concentration range of the system Ga-Sn were precisely determined. The eutectic point lies at 8.5 at.% Sn at 20.6°C. The maximum solubility of Ga in solid Sn is 7.1 at.% Ga at 20°C. An intermetallic phase does not appear in this system. The densities of the tin solid solution was determined at 20°C by X-ray measurements and also macroscopically. Measurements of thermal expansion provided values for the densities at higher temperatures. The hardness of the tin solid solution increases noticably with increasing Ga content. A calculation of the free enthalpy of mixing and the entropy of mixing of liquid Ga-Sn-alloys from the melt equilibria showed that this system has only a small tendency to separate, which tendency is expressed, among other evidence, in the slight positive deviation of the activity isotherms from the slope of Raoult's law.