Despite many investigations already performed with respect to sintering stability and grain growth vs. annealing conditions - in low yttrium doped α- Al2O3 (150 ppm) - some fundamental questions are still open. These questions concern mainly the influence of small level of impurities at grain boundary in the sintering behavior and grains growth of the materials, i.e. the microstructure function of the annealing time at annealing temperature of 16500

The attractive properties of zirconia, particularly fracture toughness, wear resistance and chemical stability, have led to vast research efforts designed to investigate, characterize and develop such materials. Applications vary from structural, mechanical, biomedical to electrical, especially the fuel cells field. The current study is aiming at preparation and structural characterization of 10% Y2O3 stabilized ZrO2 nanometric powders. The sol-gel

The X-ray, HRTEM, electric resistivities, magnetic and Mössbauer effect studies were performed on Sr2FeMoO6 samples. It was shown that the nonuniform composition inside the grains and that at the grain boundaries influence the magnetoresistive properties.

The crystal field disorder in some tetragonal and trigonal Ca-gallo-germanates, i.e., A2Fe2ZO7 and A2LnFe3Ge3O14, with A= Ba or Sr, Ln = La or Nd and Z=Ge or Si, has been studied by 57Fe Mössbauer spectroscopy. The observed distribution of the hyperfine fields is analysed from a theoretical model based on the additive perturbation approximation of crystal fields, a rigid lattice of ionic point charges and the random substitution of Fe3+/Z4+

We have studied the oxidation states of Fe and Mo and the presence of grain boundaries in the magneto resistive (MR) compounds Sr2FeMoO6 by means of x-ray photoelectron spectroscopy (XPS), Mössbauer spectroscopy and electrical resistivity measurements. XPS of the Mo 3d and Fe 3s core levels is indicating a mixed valence state involving around 30% Fe3+- Mo5+ and 70% Fe2+- Mo6+ states. Mössbauer studies confirm the presence of a valence fluctuation

The present EPR and Mössbauer results on Hg+, VO2+ and 57Fe2+ probe-ions into substituted ammonium positions of AS provide new evidence of lattice dynamics and critical anomalies near Tc together with coexistence of the paraelectric and ferroelectric phases. Numerical calculations of the electric field properties and spectral parameters of the probe-ions at two ammonium sites were performed employing specialized computing programs [6]. The temperature

Langasite family compounds have attracted a lot of attentions because of the combination of a number of nice material properties such as high piezoelectric coupling, temperature compensation and low acoustic loss. Another very important property is that the compound melts congruently so that large single crystals of langasite can be produced by the conventional Czochralski melt pulling technique. This makes the commercial scale production feasible.

Two series of PT-type materials doped with Eu+3 with the formula PbxEuyTi0.98Mn0.02O3 (x = 0.98, 1.00 and y = 0.00, 0.02, 0.04, 0.08, 0.12) were prepared by conventional ceramic technique. The compounds with compensated and uncompensated valences were sintered between 1150 and 1220°C. The two types of compounds and the content of the donor ion, Eu+3, influence the mechanical and dielectric properties of sintered samples. The spectra and data obtained

Autorii au obtinut spectre Mössbauer pe doua probe caracteristice , obtinute din doua deposite mineraliere diferite din Carpatii Romanesti. Folosind un program specializat de calcul al parametrului spectral de despicare cuadrupolara QSCOMP, dubletii observati au fost atribuitiionilor fero si feri din pozitiile octaedrale. Analiza rafinata a parametrilor spectrali ne-a permis caracterizarea ambelor stari de oxidare a configuratiilor electronice si

Este efectuat un calcul numeric al tensorului gradient de camp electric la pozitiile octaedrale si tetredrale ale Fe3+ din germantul trigonal Sr3Fe2Ge4O14, luand in considerare sarcina ionica fractionara dedusa prin procedura de sumare de valenta.Corelatia dintre valoearea calculata si cea experimentala a despicarii cuadrupolare Mössbauer evidentiaza rolul distorsiunii vecinatatii locale la nucleel de fier din acesta structura. A computation of