Researches on Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics in terms of the energy storage applications have shown that their practical applications are limited by their low effective energy storage density (W rec) and energy storage efficiency (eta). To further enhance the effective energy storage density (W rec) and energy storage efficiency (eta) of BCZT ceramics, this work dopes BCZT ceramics with various proportions of Bi(Zn0.5Zr0.5)O3(BZZ) ((1 - x)BCZT-xBZZ). Dense surface microstructure and small grain size of 3.11 mu m are realized for x = 10%. Under breakdown electric field strength (E b) of 100 kV/cm, x = 10% achieve W rec of 0.80 J/cm3 and eta of 84.3%. The ferroelectric performance is enhanced by appropriate BZZ doping amount, which densifies the system, refines grain size and facilitates the system's relaxor behavior. The enhancement in ferroelectric property is beneficial to the realization of miniaturization for the application of ceramic capacitors.
Multiferroic (1 - x)BiFeO3-xPbTiO3 binary ceramics series exhibit interesting features such as tetragonality c/a, polarization, and high Curie temperature. The composition with x = 0.3 possesses a morphotropic phase boundary (a boundary separating rhombohedral and tetragonal phases). This is a very fascinating character of this composition as it exhibits two ferroic orderings which result in the enhancement of the ferroelectric properties of the system. The structural information related to this system is very crucial to predict the ferroelectricity in this compositional series. Goldschmidt's tolerance factor is one of the important aspects to determine the stability of the perovskite (ABO3 type crystal) structure. In the present case, polycrystalline 0.7BiFeO3-0.3Pb1-xSrxTiO3 compositions with x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0, were selected to determine the effect of Sr2+ substitution at the Pb-site in the composition, and the comparative correlation studies were conducted for ferroelectric ordering in the system.
The values of thirteen elastic constants C11, C12, C13, C15, C22, C23, C25, C33, C44, C46, C35, C55, and C66 for compounds TlFeS2 and TlFeSe2 have been calculated from first principles, and the bulk moduli of elasticity, shear and Young moduli, and Poisson’s ratios have been determined. The values of the Debye temperature and Grüneisen parameters of crystals TlFeS2 and TlFeSe2 have been estimated. Propagation velocities of longitudinal and transverse acoustic waves in TlFeS2 crystals and TlFeSe2 in different crystallographic directions, as well as temperature dependences of thermodynamic functions: free energy, phonon part of internal energy, entropy, heat capacity, and thermal conductivity, have been calculated from first principles.
The glass transition and crystallization behavior of Ge17.5As15Se52.5S15 chalcogenide glass were analyzed by differential scanning calorimetry (DSC) under various heating and cooling rates ranging from 10 to 25 K/min. It was observed that both the glass transition temperature (Tg) and the peak crystallization temperature (Tp) systematically increase with increasing rate. The activation energy associated with the glass transition (Eg ≈ 250.5 kJ/mol) was evaluated using the Moynihan approach, whereas the crystallization activation energy (Ec ≈ 205.2 kJ/mol) was determined based on the Kissinger method. The calculated fragility index (m ≈ 28) suggests that the studied glass behaves as a relatively strong system. Overall, the obtained results indicate a stable thermal response and a notable resistance to crystallization, offering valuable insight into the kinetic and structural features of Ge–As–Se–S chalcogenide glass systems.
Recent investigations into the magnetic properties of high-quality GdTiO3 single crystals have reported an isotropic ferrimagnetic ordering at TN ≈ 32 K, accompanied by a positive Curie–Weiss temperature (θCW ≈ 34–35 K) in the paramagnetic regime. The original study interpreted this positive θCW as arising from antiferromagnetic interactions between the Gd and Ti magnetic sublattices, together with ferromagnetic interactions within the individual sublattices. Here we reassess this interpretation within the Néel molecular-field theory for two-sublattice ferrimagnets. The analysis shows that an antiferromagnetic inter-sublattice coupling gives a negative contribution to the asymptotic Curie–Weiss temperature. Therefore, the observed positive θCW requires a dominant positive intra-sublattice contribution. Because the Curie constant of the Gd3+ sublattice is about 21 times larger than that of the Ti3+ sublattice, the high-temperature susceptibility is expected to be governed mainly by ferromagnetic Gd–Gd correlations, whereas the antiferromagnetic Gd‒Ti coupling determines the antiparallel locking of the two sublattices in the ferrimagnetic state.
