We report the preparation
of mixed halide hybrid perovskites (CH3NH3PbI3‑x
Br
x
)
using a solvent-less mechanosynthesis route.
Compositional analysis using EDXRF microscopy has confirmed the production
of the desired materials. As relative abundance of halogen (x) increases, the tetragonal phase gradually transforms
to cubic phase and the band gap tunability of the material is observed.
Nanocrystalline Mg-Zn ferrite phases obtained by high-energy ball milling a stoichiometric (0:5 : 0:5 : 1) powder mixture of MgO, ZnO, and -Fe 2 O 3 at room temperature are subjected to postannealing treatment to study the stability of nanocrystalline ferrite phases at elevated temperatures. An X-ray diffraction (XRD) study using the Rietveld method of structure refinement reveals that ferrite phases generally decompose by releasing MgO and ZnO from ferrite lattices at 873 K. A nonstoichiometric Zn-ferrite is observed in the unmilled mixture at 973 K without MgO in the ferrite lattice, with a particle size four times (approximately 23 nm) larger than that obtained in the high-energy ball-milled samples (approximately 5 nm) at room temperature. The particle size of the unmilled and ball-milled samples increases rapidly to approximately 350 nm after postannealing at 1473 K and the XRD results agree well with the results of the direct observation of ferrite grains by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM).
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