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[en] The Curie temperatures and spin reorientation temperatures of a series of four melt-spun nanocomposite materials comprised of Nd₂Fe₁4B and varying amounts of α-Fe were measured using independent techniques. The phase constitution and grain size was assessed with synchrotron x-ray diffraction; the Curie temperatures were measured by differential thermal analysis (DTA) and dc SQUID magnetometry in the temperature range 375 K ≤ T ≤ 800 K, whereas the spin reorientation transition temperature was determined from ac susceptibility measurements taken in the range 10 K ≤ T ≤ 300 K. The Curie temperature increases with increasing excess iron content, resulting in a 18 degree enhancement over the Curie temperature of pure Nd₂Fe₁₄B for 27 wt% excess α-Fe. The spin reorientation temperatures are depressed from the single-crystal value by an average of 10 degrees. Both anomalous effects are attributed to intergranular exchange coupling present in the alloys, although the effects of uncompensated stress between the constituent phases cannot be ruled out The experimental results suggest that while the Curie temperature of the Nd₂Fe₁₄B phase may be extrinsically enhanced significantly beyond the bulk value, possibly extending the range of applications of this compound, the anisotropy may be simultaneously lowered, impeding the attainment of high coercivities in these alloys

[en] During the last decade several applications of low-pressure diamond were developed. Main products are diamond heat-spreaders using its high thermal conductivity, diamond windows with their high transparency over a wide range of wavelengths and wear resistant tool coatings because of diamonds superhardness. A short description of the most efficient diamond deposition methods (microwave, DC-glow discharge, plasma-jet and arc discharge) is given. The production and applications of diamond layers with high thermal conductivity will be described. Problems of reproducibility of diamond deposition, the influence of impurities, the heat conductivity in electronic packages, reliability and economical mass production will be discussed. (author)

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[en] Full text: Magnetic multilayer materials are becoming technologically important as they provide a more efficient means of magnetic reading and storage through utilisation of their giant magnetoresistance and oscillatory magnetic coupling. This study presents preliminary tight-binding calculations with a view of developing a consistent tight-binding model of 'spin valve' Fe-Cu-Fe tri-layer materials. Further work involves using a self-consistent tight-binding approach to obtain a more accurate picture of this system and a better understanding of surface effects at the Fe-Cu interface

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[en] The orthorhombic Tb₃Co compound exhibits both ferromagnetic and antiferromagnetic behavior below the critical temperature T_t = 72 K as evidenced by metamagnetic transitions along the a- and b-axes and ferromagnetic magnetization process along the c-axis. In the temperature interval between T_t and the Neel temperature T_N = 82 field-induced transitions along all three axes are observed. This behavior results from the complex noncomplanar magnetic structure of Tb₃Co. The metamagnetic transitions are accompanied by a significant magnetoresistance effect. The Tb₃Co single crystal has permanent magnet properties along the c-axis with the highest energy up to 140 Mg Oe at T < 4.2 K

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No abstract available