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The Alx Ga1–xN layers with a wide range of AlN molar fraction (0 < x < 0.6) were grown by ammonia MBE on (0001)‐oriented sapphire substrates using silane as the silicon dopant. The structural, electrical and optical properties of the layers were investigated by atomic force microscopy, X‐ray diffraction, Hall, Raman, photoluminescence and cathodoluminescence measurements. It was found that doping affects surface morphology, dislocation density and luminescence intensity of the Alx Ga1–xN layers. A sharp decrease of the luminescence intensity for the heavily doped GaN and Al0.3Ga0.7N layers was explained by enhancement of the nonradiative recombination rate in degenerate GaN layers and by an increase in the defect concentration in AlGaN layers. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A magnetic field has a remarkable influence on solid/solid phase transformations and it can be used to control the structure and function of materials during phase transformations. The effects of magnetic fields on diffusional solid/solid phase transformations, mainly from austenite to ferrite, in Fe-based alloys are reviewed. The effects of magnetic fields on the transformation temperature and phase diagram are explained thermodynamically, and the transformation behavior and transformed structures in magnetic fields are discussed.

A highly transparent ceramic has been synthesized from Nd 3+ :Y 2 O 3 to which 6 mol. % ZrO 2 and 25 mol. % Sc 2 O 3 or Lu 2 O 3 were added for disordering the crystal structure. Nanopowders with an average particle size of 10-15 nm served as an initial material. They were compacted by the method of uniaxial static pressing combined with ultrasonic action on nanoparticles. The compacting pressure was 200 MPa; the power of the ultrasonic generator was 1.5 kW. It has been shown that the replacement of Y by isovalent Sc and Lu ions and by heterovalent Zr ions reduces the content of pores and the sizes of crystallites. The transparency of the Nd 3+ :Y 2 O 3 ceramic with these additives reaches a maximum of 82.2%, and the 40% intensity level spectral band corresponding to the 4 F 3/2 → 4 I 11/2 transition widens from 11.4 to 40 nm.

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