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The influence of Nb₂O₅-doped concentration on the positive temperature coefficient of resistance (PTCR) effect, electrical properties and microdefects of (Ba${}_{0.95}$Sr${}_{0.05}$)(TiNb${}_x$)O₃ (BSTN) ceramics were investigated. Firing was conducted at 1350${}^{\circ }$C for 2 h in air. The donor-doped content affected the electrical properties, PTCR effect and formation of the microdefect type of the BSTN samples. The room temperature resistivity of the BSTN specimens first decreased and then increased with increasing donor-doped content in the range of 0.2 mol.% Nb${}^{5+}$ to 0.5 mol.% Nb${}^{5+}$. Moreover, the information on microdefects in BSTN ceramics was demonstrated by coincidence Doppler broadening spectrum. The influence of the defects on the PTCR characteristics of the ceramics was also revealed.

This study investigates the influence of dopant content and firing conditions on electrical properties and positive temperature coefficient of resistance (PTCR) effect of Ba${}_{1.005}$(Ti${}_{1-x}$Nb${}_x)$O₃ (BTN) ceramics sintered at different temperatures from 1070${}^{\circ }$C to 1220${}^{\circ }$C for 2 h in a reducing atmosphere and reoxidized within the temperature range of 600–750${}^{\circ }$C for 0.5–8 h. The results indicate that the room-temperature (RT) resistance of the laminated BTN specimens initially decreased and then increased as a function of the dopant concentration. Moreover, the resistance jump exhibited a contrasting tendency. Furthermore, the RT resistance of the BTN samples rapidly decreased at first and then gradually decreased with increasing sintering temperature. Meanwhile, the resistance jump of the samples increased first and then decreased. In addition, the influence of reoxidation times on the PTCR characteristics of ceramics was investigated.

This study investigates the influence of sintering conditions on electrical properties and positive temperature coefficient of resistance (PTCR) of ${\mathrm{\text{Ba}}}_{1.005}({\mathrm{\text{Ti}}}_{1-x}{\mathrm{\text{Nb}}}_x){\mathrm{\text{O}}}_3$ (BTNO) ceramics, fired at $1190^{\circ }$C for different times from 1 to 6 h in a reducing atmosphere and reoxidised within the temperature range of $600$–$900^{\circ }$C for 1 h. The results showed that the room-temperature (RT) resistance and the resistance jump of the multilayer BTNO ceramics decreased with an increase in the firing time. Furthermore, the RT resistance of the BTNO samples gradually increased at first and then rapidly increased with increasing reoxidation temperature. In addition, the influence of sintering times on the microstructure of ceramics was also investigated.

In this paper, we investigated the influence of cooling rates on electrical properties and positive temperature coefficient of resistance (PTCR) effect of (Ba_1.22−xSm_x)TiO₃ + 0.007 mol SiO₂ (BTS) ceramics, which were fired at 1200^∘C for 30 min in a reducing atmosphere and then reoxidized at 700–800^∘C for 1 h. The results showed that the room-temperature (RT) resistivity and the resistance jump of the chip-type BTS ceramics increased with an increase in the cooling rate. Furthermore, the RT resistivity of the BTS specimens gradually decreased at first and then increased with increasing donor-doping concentration. In addition, the influence of cooling rates on the microstructure of ceramics was also investigated.

Lead-zirconate-titanate PbZr_1-xTi_xO₃ has superb ferroelectric properties in x~0.48 morphotropic phase boundary phase. In bulk form it has a P4mm tetragonal crystal structure of lattice parameters a=0.4036 nm and c=0.4146 nm at room temperature or above, and a Cm monoclinic structure of a=0.5722 nm, b=0.5710 nm, c=0.4137 nm and β=90.50° at lower temperatures. A new polymorph lies in an orthorhombic structure of a=0.4038 nm, b=0.4017 nm, and c=0.4148 nm in small particles of size such as 20 nm. It has an enhanced value of density of 8.033 g/cm³ relative to 8.006 g/cm³ in the tetragonal or 8.000 g/cm³ in the monoclinic bulk structure in a rather incompressible and hard material. The result is analyzed with X-ray diffraction of the sample of nanoparticles.

The comparison of the low temperature sintering and the microwave dielectric properties of Li₂MgSiO₄ (LMS) ceramics prepared by citrate gel (CG) route and solid state (SS) ceramic route are discussed in this paper. The LMS prepared using CG route sintered at 1175°C/2 h has ε_r = 5.3 and tan δ = 1 × 10⁻³ at 9 GHz. The sintering temperature of LMS is lowered to 950°C with the addition of 5 wt% lithium magnesium zinc borosilicate glass and has ε_r = 5.6 and tan δ = 2 × 10^-3 at 9 GHz. The amount of glass required to lower the sintering temperature of ceramics prepared using CG are slightly higher than that of SS ceramic route. The LMS ceramics prepared using SS ceramic route shows excellent microwave dielectric properties with low sintering temperature compared to CG route.