Advanced composite materials reinforced with high-performance fibers like carbon, glass, aramid, or ultra-high-molecular-weight polyethylene are widely used as lightweight materials in the fields of automotive, aerospace, sports, and protection. However, nearly always these composites are opaque and/or absorb light, which greatly limits their application in areas where high optical transparency is desired such as impact-resistant windows and visors. In this work, composite laminates that combine high optical clarity with high mechanical properties are reported for the first time using highly oriented high-density polyethylene (HDPE) films as the reinforcing phase. A high optical transparency with a far-field light transmittance of around 85% was achieved for four-layer HDPE-reinforced laminates sandwiched between glass or polycarbonate (PC) sheets with either unidirectional (UD) or bidirectional (BD) orientations. In combination with outer layers of glass or PC, the fabricated transparent composite laminates show high tensile strength and also high penetration energy absorption, outperforming existing transparent materials like glass, laminated glass, or PC. These transparent composites combine both high mechanical performance and high optical clarity, providing great potential for future applications in structural glazing, automotive glazing, safety shields, visors, and displays for portable electronics.

Single phase Bi3Nb1.125Fe0.0625Co0.0625Ti0.75O9 ceramics with grain-oriented microstructure were prepared using spark plasma sintering. The ferroelectricity was confirmed by the piezoelectric activity of the ceramics measured at room temperature (d(33) = 5.6 pC/N). The magnetic measurements evidenced an antiferromagnetic behaviour which can be ascribed to the superexchange interaction of Fe3+-O-Fe3+ and Co3+-O-Co3+. The ferroelectric Curie point and the antiferromagnetic Neel temperature of the ceramic were identified at 1155 K and 153 K, respectively. The material shows multiferroic behaviour below 153 K. (C) 2019 Elsevier B.V. All rights reserved.

Highly textured Ba2Bi4Ti5O18 ceramic was prepared by spark plasma sintering (SPS). X-ray diffraction of the ceramics revealed the coexistence of a major ferroelectric phase (Space group, SG: B2cb) and a minor para-electric phase (SG: I4/nunm) at room temperature. A diffused phase transition was observed at around 240 degrees C. The evolution of the switching current peaks in the electric current vs. electric field (I-E) loops with increasing temperature was interpreted by the structural changes and temperature dependent polarisation reversal processes. The slim polarisation vs. electric field (P-E) loops, the extra switching current peaks in the I-E loops and the non-zero piezoelectric d(33) coefficient indicate that Ba2Bi4Ti5O18 is a relaxor ferroelectric material. The recoverable energy density (0.41 +/- 0.01 J/cm(3)) of Ba2Bi4Ti5O18 ceramics in the perpendicular direction to the SPS pressing direction is close to that of Pb(Mg1/3Nb2/3)O-3-based ceramics. The obtained results suggest Ba2Bi4Ti5O18 ceramics might be promising for energy storage applications.

To improve dielectric, piezoelectric and ferroelectric properties of Sr2Bi4Ti5O18 ceramics, highly textured, dense ceramics are required. Highly grain-oriented Sr2Bi4Ti5O18 textured ceramics were prepared by pressure-assisted spark plasma sintering. The textured ceramics exhibited crystallographic anisotropy with c-axis oriented grains (Lotgering factor of 71%). The dielectric permittivity, piezoelectric constant and ferroelectric remnant polarization measured on the ceramics in the direction perpendicular to the pressure applied during sintering are higher than those along the parallel direction. These improved properties are related to the preferred polarization rotation in the textured microstructures prepared during spark plasma sintering.

A new single phase Aurivillius structured ceramic shows room temperature multiferroic behavior.