1,721,003 research outputs found
Local chemical environment of Nd3+, Eu3+, and Er3+ luminescent centers in lead germanate glasses
No full textExperimental estimation of the cooperative Jahn-Teller energy in orbitally ordered KCu0.8Mg0.2F3 perovskite
No full textDevitrification kinetics of PbGeO3: an isothermal and non-isothermal study
No full textThe devitrification of glassy PbGeO3 was studied and interpreted by means of isothermal and non-isothermal Johnson-Mehl-Avrami equations. In the case of the non-isothermal approach, several approximated equations proposed by various authors were considered in order to obtain both the activation energy Ea and the Avrami morphological coefficient n of the crystallisation process. A critical discussion of the Avrami coefficient on the basis of experimental morphological evidence is also presented.. A critical discussion of the Avrami coefficient on the basis of experimental morphological evidence is also presented
EXAFS-XANES Evidence of in Situ Cesium Reduction in Cs-Ru/C Catalysts for Ammonia Synthesis
No full textTransport properties of Al doped SmBa2Cu3O6+d superconductor. Part I: oxygen non-stoichiometry and diffusion
No full textThe oxygen non-stoichiometry and diffusion in SmBa2Cu3 −xAlxO6+ δ superconductor were investigated by means of thermogravimetric
analysis (TGA) in a wide P(O2) (1 P(O2) 10−4 atm) and T (400 T 800 ◦C) range. Thermogravimetric data at fixed oxygen partial
pressures were collected using temperature steps and long isotherms. The samples used for TG analysis were previously sieved in order to
obtain powders of known particle dimensions. This procedure allowed to determine both the oxygen non-stoichiometry and its diffusion
coefficient in SmBa2Cu3 −xAlxO6+ δ .With respect to undoped SmBa2Cu3O6 + δ, the corresponding δ values are quite similar in oxidising
conditions, while the doped material loses less oxygen than the pure one in reducing conditions. For what concern the oxygen diffusion,
aluminium doping does not affect the activation energy for that process; on the opposite the absolute D value is at least one order of
magnitude lower than in the pure phase and the D varies as a function of P(O2). All the above features are interpreted under the hypothesis
that, in the thermodynamic conditions of the experiments, only O4 oxygen ions and sites surrounded by two Cu1 ions are involved into
gas–solid equilibria and into diffusion process
Experimental disentangling of orbital and lattice energy scales by inducing cooperative Jahn-Teller melting in KCu1-xMgxF3 solid solutions
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