The structure and magnetic properties of La2NiMnO6 nanoparticles with sizes ranging from about 16 to 66 nm synthesized by a sol-gel method have been investigated. The magnetic measurements reveal that the rates of disordered phases increase as particle size decreases, which can be deduced from the changes of Curie temperature and the occurrence of glasslike behaviors, and the similar saturation magnetization was obtained at 4 K. While the particle size becomes smaller, two broad peaks of Raman spectrum at around 535 and 670 cm−1, which are assigned to antisymmetric stretching mode and symmetric stretching mode, move to higher and lower frequencies than the corresponding modes of the bulk compound, respectively. The two peaks also become broader, while the intensity becomes relatively weaker with the decrease in nanoparticle size. All results support that the trend of Mn4++Ni2+→Mn3++Ni3+ bring locally cooperative Jahn–Teller deformation and charge disproportion, and demonstrate that the nanometer effect is a crucial factor to influence the properties of La2NiMnO6.

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The magnetic properties of the double perovskite La2NiMnO6 polycrystalline sample have been investigated by magnetometry and electron spin resonance. The magnetization curve shows a paramagnetic-ferromagnetic transition at TC∼280K. However, the electron spin resonance spectra reveal that a pure paramagnetic regime only exists above T*∼390K in which the behaviors of the spectra can be well described by the small polaron hopping model. Between TC and T*, a short-range magnetic ordering appears which maybe derives from the correlation of those magnetic polarons. The possible relationship between those polarons and the observed multifunctions in La2NiMnO6 is briefly discussed.

Construction site layout is concerned with the existence, positioning, and timing of the temporary facilities that are used to carry out a construction project. Typically these problems are very complicated to formulate and difficult to solve. They are, however, very important to virtually any construction project, since the site layout can significantly affect the cost of the project. This paper describes the general site layout problem from both a theoretical and a practical point of view. It proposes genetic algorithms as a possible solution technique and includes a theoretical example of positioning temporary facilities. This is extended to a practical problem in which the cost of movement is modeled realistically using an augmented genetic algorithm. Some preliminary conclusions are drawn for the application of genetic algorithms to construction site layout problems.