Dielectric, thermal, and microhardness properties of high-performance barium titanate (BaTiO 3 )-filled polyetheretherketone (PEEK) composites were studied. BaTiO 3 was varied from 0 vol.% to 67 vol.% in the PEEK matrix. The dielectric constant of the composites measured at 1 MHz increased approximately 14-fold. There was no dispersion in the dielectric constant with frequency between 10 kHz and 15 MHz. The Lichtenecker equation and modified Lichtenecker equation agreed well with the experimental data. The dissipation factor of the composites varied from 0.0056 to 0.0096. Scanning electron microscopy showed uniform dispersion of BaTiO 3 in the matrix. The microhardness of the composites increased by more than 2.5-fold compared with pure PEEK. The coefficient of thermal expansion measured below and above the glass-transition temperature was reduced by up to 56%. These results make these composites promising candidate high-temperature organic substrates.

(Ni1−xZnx)Nb2O6, 0≤x≤1.0, ceramics with >97% density were prepared by a conventional solid‐state reaction, followed by sintering at 1200°–1300°C (depending on the value of x). The XRD patterns of the sintered samples (0≤x≤1.0) revealed single‐phase formation with a columbite (Pbcn) structure. The unit cell volume slightly increased with increasing Zn content (x). All the compositions showed high electrical resistivity (ρdc=1.6±0.3 × 1011Ω·cm). The microwave (4–5 GHz) dielectric properties of (Ni1−xZnx)Nb2O6 ceramics exhibited a significant dependence on the Zn content and to some extent on the morphology of the grains. As x was increased from 0 to 1, the average grain size monotonically increased from 7.6 to 21.2 μm and the microwave dielectric constant (ɛ′r) increased from 23.6 to 26.1, while the quality factors (Qu×f) increased from 18 900 to 103 730 GHz and the temperature coefficient of resonant frequency (τf) increased from −62 to −73 ppm/°C. In the present work, we report the highest observed values of Qu×f=103 730 GHz, and ɛ′r=26.1 for the ZnNb2O6‐sintered ceramics.

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Dense Ba 1-x Pb x TiO 3 (x = 0-0.20) samples (>90% TD) were fabricated through a solid-state reaction route involving wet ball milling for 24 h and calcination at 1150°C for 4 h, followed by sintering at 1300°C for 4 h. XRD results for all the samples revealed a tetragonal perovskite (P4mm) crystal structure. Increased substitution of Pb caused monotonic growth in the tetragonality character of the perovskite phase. Although, the value of ε r ʹ dropped from an initial value of 3000 for x = 0 (pure BaTiO 3) to 400 for x = 0.20 samples, the losses (tanδ) interestingly declined almost to half. A substantial increase in the Curie temperature from 120°C for x = 0°C to 180°C for x = 0.15 samples was noted. P-E loop analysis revealed an increase in the saturation polarization by almost 1.5 times, moreover, in the remnant polarization by six times with Pb-substitution. The d 33 values demonstrated an increase from 95 pC/N for pure BaTiO 3 samples to 220 pC/N for x = 0.15 samples.

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