Single crystals of PrCo2 have been grown from flux starting from Pr0.44Co0.56 that was synthesized by arc melting of stoichiometric mixtures of the elements. The Pr0.44Co0.56 ingot was loaded in a ...Boron Nitride (BN) crucible and sealed inside a quartz tube under vacuum. The quartz ampoule was heated to 1203 K, and then slowly cooled down to 923 K at a rate of 2 K/h. The obtained crystals have octahedral shapes and are of cubic C15 Laves phase structure confirmed by room temperature powder and single-crystal X-ray diffraction measurements. Magnetic susceptibility data show the Curie temperature TC = 46.7 K. The experimental value of saturation magnetization Ms = 3.2 μB/f.u is consistent with our theoretical calculations.
This paper reviews a feature of atomically‐clean quasicrystal surfaces that distinguishes them from surfaces of crystalline materials. That feature is a high degree of heterogeneity among different ...terraces, and among structurally‐identical adsorption sites. The heterogeneity can be both structural and chemical in origin. A large variability is expected even for a surface which is perfectly bulk‐terminated, and we call this intrinsic heterogeneity. Additional variability can derive from the surface preparation process, which can yield metastable structures. We call this extrinsic heterogeneity. Experimental evidence is given for both cases. This heterogeneity can be an important factor in understanding and predicting surface phenomena such as chemisorption.
The Ni–Pr system is investigated via experiments and thermodynamic modeling. In the experimental part, five alloys with compositions of Ni–96
at.% Pr, Ni–85
at.% Pr, Ni
3Pr, Ni
5Pr and Ni–5
at.% Pr ...were prepared by arc melting pure Ni and Pr slugs and annealing the alloys at 500
°C for 2 weeks. The annealed alloys were then subjected to differential thermal analysis (DTA) measurements. The decomposition temperatures of Ni
7Pr
2 (1162
°C), Ni
3Pr (1029
°C), Ni
2Pr (921
°C), dhcp (Pr) (780
°C), the eutectic reaction temperature of liquid
↔
fcc (Ni)
+
Ni
5Pr (1280
°C) and the congruent melting point of Ni
5Pr (1385
°C) were determined by DTA, respectively. In the modeling part, the available phase equilibrium and thermodynamic data in the Ni–Pr system were analyzed by using thermodynamic models for the Gibbs energies of individual phases. An optimal set of thermodynamic parameters was obtained using WinPhad software. The calculated phase equilibria and thermodynamic properties from the model parameters were compared to the corresponding experimental data and good agreement was obtained.
Elastic properties of MnSi, FeSi and CoSi Petrova, Alla E; Krasnorussky, Vladimir N; Yuhasz, William M ...
Journal of physics. Conference series,
01/2011, Letnik:
273, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Measurements of sound velocities in single crystals of MnSi, FeSi and CoSi were performed in the temperature range 2.5-300 K and elastic constants were calculated. The temperature dependence of the ...elastic constants reveal nontrivial features, reflecting specifics of the magnetic and electronic subsystems in these materials.
The Nd–Ni system has been investigated via experiments and thermodynamic modeling. In the experimental part, alloys across the entire composition range were prepared by arc melting pure Nd and Ni ...slugs and annealing the alloys at 500
°C (<70
at.% Ni) and 800
°C (>70
at.% Ni) for 2 weeks. The annealed alloys were then subjected to differential scanning calorimetry and differential thermal analysis (DTA) measurements to determine the invariant reaction temperatures. Except for the peritectic reaction liquid
+
Nd
7Ni
3
↔
Nd
3Ni and the polymorphous phase transformation of Nd
2Ni
7 found in this study, all the other invariant reactions are confirmed to be the same types but with significant different temperatures as reported results. In the modeling part, the available phase equilibrium and thermodynamic data in the Nd–Ni system were analyzed by using thermodynamic models for the Gibbs energies of individual phases. An optimal set of thermodynamic parameters were obtained using WinPhad software. The calculated phase equilibria and thermodynamic properties from the model parameters were compared to the corresponding experimental data and good agreement was obtained.
Ferromagnetic shape memory Ni–Mn–Ga has been shown to exhibit deformations of up to 9.5% when driven with quasistatic fields. This article is focused on the use of Ni–Mn–Ga as the active element in a ...dynamic transducer consisting of a solenoid and a low-reluctance, closed magnetic path. Despite the absence of a restoring force in this configuration, we have shown in prior studies recoverable compressible strains of 1/4 4100 m, which are attributable to internal bias stresses built in the material during manufacture. In this study, we experimentally establish the presence of a modulus defect in Ni50Mn28.7Ga21.3, whereby the elastic modulus increases as much as 255% upon increasing the applied magnetic field from zero to 380 kA/m DC. Experimental measurements are conducted under both mechanical and magnetic excitation, and analyzed in combination with vibratory models for the system. While in our experiments the attractive magnetic forces between the transducer poles may contribute to the total modulus increase, the presence of a modulus change associated with the Ni–Mn–Ga element is substantiated. Dynamic Ni–Mn–Ga transducers offer an attractive mechanism for electrical tuning of the modulus, with potential application in active vibration absorption problems.
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