DSpace Colección :http://repositorio.espe.edu.ec/handle/21000/122382024-03-28T12:46:38Z2024-03-28T12:46:38ZSynthesis and Characterization of LaNi0.5Ti0.5O3 and La2NiTiO6 Double Perovskite Nanoparticles.Córdova Calderón, José Antoniohttp://repositorio.espe.edu.ec/handle/21000/332102022-09-30T08:26:59Z2022-08-15T00:00:00ZTítulo : Synthesis and Characterization of LaNi0.5Ti0.5O3 and La2NiTiO6 Double Perovskite Nanoparticles.
Autor: Córdova Calderón, José Antonio
Abstract: In the present work, LaNi0.5Ti0.5O3 and La2NiTiO6 nanoparticles were synthesized by the modified Pechini method. LaNi0.5Ti0.5O3 was calcined at 1073 K for 17 h or 100 h, while La2NiTiO6 was calcined at 1273 K for 135 h. The double perovskite calcined at 1073 K for 17 h presented orthorhombic symmetry with Pbnm space group, mean particle size was 31.9 ± 1 nm, random ordering of Ni2+ and Ti4+ cations, Néel temperature close to 15 K, and magnetic moment of 1.29 µB. By increasing the calcination time, this material showed the same symmetry and space group, a mean particle size of 50.7 ± 2 nm, short-range ordering of Ni2+ and Ti4+ cations, Néel temperature around 12 K, and magnetic moment of 0.96 µB. La2NiTiO6 presented a monoclinic crystal structure, with P21/n space group, mean particle size of 80.0 ± 5 nm, rock salt ordering of Ni2+ and Ti4+, Néel temperature of approximately 23 K, and magnetic moment of 2.75 µB.2022-08-15T00:00:00ZNew Refrigerant Molecules from Structure Optimization.Rosero Hidalgo, Cristhian Raúlhttp://repositorio.espe.edu.ec/handle/21000/263642021-10-16T08:23:32Z2021-09-14T00:00:00ZTítulo : New Refrigerant Molecules from Structure Optimization.
Autor: Rosero Hidalgo, Cristhian Raúl
Abstract: In the present work, various objective function were formulated and optimized using the mixed integer nonlinear programming and the generalized reduced gradient nonlinear method from the solvertoolof Microsoft® Excel 2016, respectively. The CH3FO2, C2H4F2O, CH2F2O2, CH2F2O, C3H4F2, andtheC2H2F2O molecules were found to meet structural feasibility constraints and physical properties from refrigerant molecules and have not previously been reported in the literature. The senew refrigerants present global warming potential values similar to that from the R-134 and Freon 12 refrigerants and null ozone depletion potential. Moreover, these molecules are normally flammable, assimilarasto R-134 a refrigerant. TheCH3FO2, C2H4F2O, CH2F2O2, C2H2F2O, and CH2F2O show toxicity values similarto R-134a and Freon 12 refrigerants.2021-09-14T00:00:00Z