The impact of cation distribution on electronic structure and magnetic properties is investigated by the first-principle calculation. The structure optimization is based on generalized gradient approximation GGA exchange-correlation and projector augmented wave method. The optimized structures of inverse and normal copper ferrite are tetragonal c /a=1.06 and cubic, respectively. The optimized s...

Pure nanocrystalline titanium Oxide (TiO2) powder has been synthesized by the sol-gel technique using titanium tetra-isopropoxide as the starting precursor. As-prepared samples were calcined at different temperatures, 400, 600, 800 and 900°C. X-ray diffraction (XRD) analysis was used to find the crystalline structure and changes in the polymorphs with calcination. The as-synthesized TiO2 powder...

The crystal structure of lead tungstate, PbWO4, is tetragonal, scheelite type, space group I41/a. This compound is frequently subjected to lead deficiency, due to the difference in the vapour pressure of the two oxides, WO3 and PbO, used in the crystal growth. One group has reported that lead vacancies can order in a crystal structure derived from the scheelite type, but of lower symmetry and d...

Barium titanate is a member of a large family of compounds with the general formula ABO3 called perovskites, as the crystal size of barium titanate increases and at critical crystalline size crystal structure of barium titanate transformed from cubic to tetragonal. Transformation of crystal structure is also take place at Curi temperature. Cubic structure show paramagenatic behavior while tetra...

The PZT material near the morphotropic phase boundary where a monoclinic phase was observed is studied in this paper. A theory of the tetragonal to monoclinic phase transition was developed within the Landau free energy approach. The order parameter is the electric polarization vector. The phase transition from the tetragonal to the monoclinic phase is of the first order near the second order. ...

Methylammonium lead tri-iodide is a polymorphic material with two temperature-induced phase transitions at 165 K and 327 K, accompanied by an orthorhombic-to-tetragonal and a tetragonal-to-cubic lattice modification. Understanding the origins of these transitions as well as their implications on the crystal structure of the material is fundamental for its technological optimization. Here, we us...

In order to study the crystal structure, phase relationships, and magnetic properties of the system Tb5−xLaxSi2Ge2, a series of polycrystalline samples with compositions ranging from x = 0 to x = 5 have been synthesized and characterized in detail. At room temperature, two structures have been detected: Compounds in the concentration range 0 x < 1 present a monoclinic Gd5Si2Ge2-type structure, ...

We report the dynamics of the structure of CaSiO3 perovskite from ab initio molecular dynamics (AIMD) calculations at high pressure (P up to 130 GPa) and high temperature (T up to 5000 K). Our calculations indicate three separate stability fields: orthorhombic, tetragonal and cubic, with the tetragonal phase dominating the pressure and temperature region between room temperature and 4000 K. The...