In the present study, the effects of magnesia particles on thermal, dynamic mechanical, morphological, and surface properties of polystyrene resin are investigated. In general, the addition of magnesia particles in polystyrene matrix increases the thermal stability, storage modulus, and wettability, on other hand does not affect the molecular mobility. SEM results showed a limited distribution of magnesia particles in the polystyrene matrix at 15 wt.%.

Quantum chemical calculations at DFT/B3LYP level of theory with 6-31G, 6-311G, and 6-311G(d,p) basis sets were done to correlate the inhibition of mild steel corrosion in 1 M H 2 SO 4 by four dianiline Schiff bases namely N,N'-Bis(benzylidene)-4,4'-dianiline (DAA), N,N'-Bis (benzylidene)-4,4'-methylenedianiline (MDAA), N,N' Bis(benzylidene)-4,4'-sulphonyldianiline (SDAA) and N,N'-Bis(benzylidene)-4,4'-oxydianiline (ODAA) with their electronic and structural properties. Quantum chemical parameters such as the E HOMO , E LUMO , energy gap (∆E), dipole moment (µ), global softness (σ), and global hardness (η) were calculated and discussed to provide valuable explanations for the reactivity and selectivity of the studied inhibitors. The results obtained showed a certain relationship to the experimental inhibition efficiency results earlier reported.

Piezoelectric ceramics are widely used in various applications such as lead zirconate titanate (PZT), especially after the development of acceptor or donor dopant. This is why all studies are interested in the effect of dopants on the properties of PZT ceramics are in great demand. In this work, the polycrystalline samples of Pb(0.95-x) La 0.03 Sm0.02 Bi x(Zr0.3,Ti0.7)O3 (x=0, 0.02, 0.04, 0.06, 0.08, 0.1) were prepared by a high-temperature solidstate reaction technique. Scanning electron micrograph (SEM) and X-ray diffraction (XRD) techniques was employed to examine the crystallization of the ceramics. The results of XRD show that the phase structure of the samples is tetragonal. The dielectric constant and the dielectric loss of the investigated samples decreased with increase in the frequency, then we can say that the doping with the Bi on PLSZT, enhances the dielectric and electrical properties. KEYWORDS: ferroelectric, microstructure, piezoelectric ceramics, dielectric properties. MOTS-CLÉS: ferroé lectrique, la microstructure, cé ramique pié zoé lectrique, proprié té s dié lectriques.

This work aims at, to study the influence of Nd 3+ on the dielectric properties of a ceramics material of general formula: Pb[Zr0.45 Ti0.45 (Zn1/3, Sb2/3) 0.1]O3 and of structure perovskite. The selected samples were prepared by the method of synthesis with solid way. The study of the dielectric properties of the system showed that the values of the permittivity, the resistivity, increase with the addition of Nd +3 1%.