Piezo-catalytic degradation of Havriliak–Negami type

Two sets of experimental data of piezo-catalytic degradations are adapted to fit with three-parameter Mittag–Leffler functions. One set is degradation on methyl orange (MO) using catalysis of nano-sized barium titanates, and another set is on Rhodamine-B (RhB) using molybdenum disulfide nano-flowers as catalysts. The fitting results suggest that these piezo-catalytic degradations can be described either as Davidson–Cole type response function or Havriliak–Negami type of dielectric relaxation. This work confirms completely the universality in chemical reaction kinetics, which can be described by fractional differential equations with Mittag–Leffler functions as their solutions.

Barium titanate via thermal decomposition of Ba,Ti-precursor complexes: The nature of the intermediate phases

The thermal decomposition of Ba,Ti-precursor complexes, containing organic ligands and suitable for the single-source preparation of nanocrystalline BaTiO3, leads firstly to the segregation of specific Ba-rich and Ti-rich phases. Quantitative electron energy loss spectroscopy and powder X-ray diffraction data indicated that the (i) Ba-rich phase is a BaO-stabilised variant of the calcite-type high-temperature modification of BaCO3 and (ii) Ti-rich phases are represented by low crystalline barium titanates with the general Ba:Ti ratio close to 1:4. The subsequent solid state reaction between these phases results then in the formation of BaTiO3.