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Immiscible semiconductors are of premier importance since the source of lighting has been replaced by white light-emitting-diodes (LEDs) composed of thermodynamically immiscible InxGa1−xN blue LEDs and yellow phosphors. For realizing versatile deep-ultraviolet to near-infrared light-emitters, Al1−xInxN alloys are one of the desirable candidates. Here we exemplify the appearance and self-formation sequence of compositional superlattices in compressively strained m-plane Al1−xInxN films. On each terrace of atomically-flat m-plane GaN, In- and Al-species diffuse toward a monolayer (ML) step edge, and the first and second uppermost < 1 - 1 - 20 > cation-rows are preferentially occupied by Al and In atoms, respectively, because the configuration of one In-N and two Al-N bonds is more stable than that of one Al-N and two In-N bonds. Subsequent coverage by next < 1 - 1 - 20 > Al-row buries the < 1 - 1 - 20 > In-row, producing nearly Al0.5In0.5N cation-stripe ordering along [0001]-axis on GaN. At the second Al0.72In0.28N layer, this ordinality suddenly lessens but In-rich and In-poor < 1 - 1 - 20 >-rows are alternately formed, which grow into respective {0001}-planes. Simultaneously, approximately 5-nm-period Al0.70In0.30N/Al0.74In0.26N ordering is formed to mitigate the lattice mismatch along [0001], which grow into approximately 5-nm-period Al0.70In0.30N/Al0.74In0.26N { 10 1 - 2 } superlattices as step-flow growth progresses. Spatially resolved cathodoluminescence spectra identify the emissions from particular structures. [ABSTRACT FROM AUTHOR]

Abstract: Single crystals of iron(II) pyroborate, Fe2B2O5, were prepared at 1000–1050°C under an argon atmosphere. The crystals were transparent, yellowish in color and needle-like or columnar. The crystal structure of Fe2B2O5 was analyzed by single-crystal X-ray diffraction. Refined triclinic unit cell parameters were a=3.2388(2), b=6.1684(5), c=9.3866(8)Å, α=104.613(3)°, β=90.799(2)° and γ=91.731(2)°. The final reliability factors of refinement were R1=0.020 and wR2=0.059 [I > 2σ(I)]. Transmittance over 50% in the visible light region from 500 to 750nm was observed for a single crystal of Fe2B2O5 with a thickness of about 0.3mm. The light absorption edge estimated from a diffuse reflectance spectrum was at around 350nm (3.6eV). Magnetic susceptibility was measured for single crystals at 4–300K. Fe2B2O5 showed antiferromagnetic behavior below the Néel temperature, T N≈70K, and the Weiss temperature was T W=36K. The effective magnetic moment of Fe was 5.3μ B. [Copyright &y& Elsevier]