NTC (negative temperature coefficient) thermistors are semiconductor ceramics whose resistance decreases with increasing temperature, making them essential components in various temperature sensing applications. Typically, ceramic materials are sintered at high temperatures exceeding 1,150°C. However, in laminated devices incorporating internal electrodes, co-sintering can lead to cracking and mechanical failure due to mismatches in the thermal expansion coefficients between the ceramic layers and metal-based electrodes. Moreover, the use of noble metal electrodes increases production costs. To address these challenges, a low-temperature sintering approach is required. Previous studies have demonstrated that incorporating glass frit can reduce the sintering temperature of ceramics, although this often results in increased electrical resistance. In this study, NiMnCoO₄ (NMC) ceramics, as a representative NTC thermistor composition, were prepared with the addition of 10 wt% glass frit. To mitigate the resulting increase in resistivity, trace amounts (1 wt%) of various metal oxides, including CuO, ZnO, and MnO, were introduced. Among these, the addition of CuO notably decreased both the resistivity and B constant values. In contrast, MnO had little effect on resistivity, while ZnO led to an increase. With respect to the B25/85 constant, samples containing MnO and ZnO exhibited higher values than those without metal oxide additives. These findings indicate that the incorporation of 1 wt% CuO is effective in reducing the increased resistivity in NMC ceramics subjected to low-temperature sintering via glass frit addition.

NTC thermistors are essential components widely used for temperature sensing in various electronic sensor applications. However, conventional NTC thermistor ceramics typically require high sintering temperatures above 1150℃, necessitating the use of high-cost noble metal electrodes such as palladium (Pd) or platinum (Pt), which increases the overall manufacturing cost. In this study, low-melting-point oxides were successfully introduced as sintering aids to reduce the sintering temperature of NiMnCoO₄-based semiconducting ceramics. As the additive content increased, the B constant and average grain size exhibited an increasing trend, while the sample containing 5 wt% additives showed the lowest room-temperature resistivity. Furthermore, samples sintered at 1000℃ demonstrated slightly higher room-temperature resistivity and B constant values compared to those sintered at 1150℃. These results confirm that the addition of low-melting-point oxides is effective in lowering the sintering temperature of NiMnCoO₄ ceramics, suggesting the potential for reducing production costs and improving design flexibility in thermistor fabrication.

The expansion of lithium-ion battery usage beyond portable electronic devices to electric vehicles and energy storage systems is driven by their high energy density and favorable cycle characteristics. Enhancing the stability and performance of these batteries involves exploring solid electrolytes as alternatives to liquid ones. While sulfide-based solid electrolytes have received significant attention for commercialization, research on amorphous-phase glass solid electrolytes in oxide-based systems remains limited. Here, we investigate the glass transition temperatures and sintering behaviors by changing the molecular ratio of Li₂O/B₂O₃ in borate glass comprising Li₂O-B₂O₃-Al₂O₃ system. The glass transition temperature is decreasing as increasing the amount of Li₂O. When we sintered at 450℃, just above the glass transition temperature, the samples did not consolidate well, while the proper sintered samples could be obtained under the higher temperature. We successfully obtained the borate glass ceramics phases by melt-quenching method, and the sintering characteristics are investigated. Future studies could explore optimizing ion conductivity through refining processing conditions, adjusting the glass former-to-modifier ratio, and incorporating additional Li salt to enhance the ionic conductivity.

Laser-induced plasmonic sintering of metal nanoparticles (NPs) is a promising technology to fabricate flexible conducting electrodes, since it provides instantaneous, simple, and scalable manufacturing strategies without requiring costly facilities and complex processes. However, the metal NPs are quite expensive because complicated synthesis procedures are needed to achieve long-term reliability with regard to chemical deterioration and NP aggregation. Herein, we report laser-induced Ag NP self-generation and sequential sintering process based on low-cost Ag organometallic material for demonstrating highquality microelectrodes. Upon the irradiation of laser with 532 nm wavelength, pre-baked Ag organometallic film coated on a transparent polyimide substrate was transformed into a high-performance Ag conductor (resistivity of 2.2 × 10^-4 Ω·cm). To verify the practical usefulness of the technology, we successfully demonstrated a wearable transparent heater by using Ag-mesh transparent electrodes, which exhibited a high transmittance of 80% and low sheet resistance of 7 Ω/square.

Phase evolution, thermal and microwave dielectric properties of cordierite-Al₂O₃ composite were investigated. As the content of Al₂O₃ increased, mullite, sapphirine, and spinel were formed as secondary phases, implying that cordierite may be decomposed by the reaction with Al₂O₃. All sintered specimens exhibited dense microstructures. The densification occurred through liquid phase sintering. As the content of Al₂O₃ increased, the thermal expansion coefficient and the dielectric constant increased, whereas the quality factor decreased. The thermal expansion coefficient, the dielectric constant, and the quality factor of the 90 wt% cordierite 10 wt% Al₂O₃ composite sintered at 1,425℃ were 2.9×10^-6 K^-1, 5.1, and 34,844 GHz, respectively.

BaTiO₃ powder was synthesized by a solid-state reaction using BaCO₃ and TiO₂. Different calcination temperatures (800℃, 850℃, 900℃, and 950℃) were set to investigate their effects on the properties of BaTiO₃ powder. The synthesized BaTiO₃ phase was confirmed to be a single phase by XRD, and the tetragonality (c/a) and crystallite size were calculated. Thereafter, each calcinated BaTiO₃ was sintered at five different sintering temperatures (1,100℃, 1,150℃, 1,200℃, 1,250℃, and 1,300℃), and the tetragonality, density, porosity, dielectric constant, and grain size were measured. As the calcination temperature increased, the tetragonality and crystallite size also increased, to 1.008 and 66 nm, respectively, at 950℃. Moreover, most pellets showed increased density, dielectric constant, and tetragonality as the sintering temperature increased up to 1,250℃; the same parameters slightly decreased at 1,300℃. It is noteworthy that the tetragonality of BaTiO₃ at 1,250℃ exhibits a very high c/a value of 1.0084. In addition, the grain size and dielectric constant measured near the Curie temperature increased as the sintering temperature increased.

This study investigated the microstructure and piezoelectric properties of lead-free 0.74(Bi_1/2Na_1/2)TiO3-0.26SrTiO₃ (BNST26) piezoelectric ceramics sintered using a microwave furnace. For comparison, specimens were also prepared using a conventional furnace sintering (CFS). Average grain sizes of 2.4 μm and 3.2 μm were obtained in the sample sintered at 1,100℃ for 5 min using microwave sintering (MWS) and at 1,175℃ for 2 h using CFS, respectively. To quantify the changes in the microstructures and electrical properties according to the sintering conditions, the polarization hysteresis, bipolar and unipolar strain curves, and temperature dependence of permittivity were evaluated. As a result, it was determined that the Pmax (maximum polarization), Pr (remanent polarization) and Smax (maximum strain) values tend to increase with the average grain size. Based on these results, it is concluded that the MWS method can produce lead-free ceramics with superior performance in a relatively short time compared to the conventional CFS method.

This study introduces a new investigation report on the microstructural and electrical property changes of ZnO-Zn₂BiVO₆-Mn₃O₄ (ZZMn), where 0.33 mol% of Mn₃O₄ and 0.5 mol% of Zn₂BiVO₆ were added to ZnO (99.17 mol%) as liquid phase sintering aids. Zn₂BiVO₆ contributes to the decrease of sintering temperatures by up to 800℃, and segregates its particles at the grain boundary, while Mn₃O₄ enhances α, the nonlinear coefficient, of varistor properties up to α＝62. In comparison, when the sintering temperature is increased from 800℃ to 1,000℃, the resistivity of ZnO grains decreases from 0.34 Ωcm to 0.16 Ωcm, and the varistor property degrades. Oxygen vacancy (V_o^·) (P1, 0.33~0.36 eV) is formed as a dominant defect. Two different kinds of grain boundary activation energies of P2 (0.51~0.70 eV) and P3 (0.70~0.93 eV) are formed according to different sintering temperatures, which are tentatively attributed to be ZnO/Zn₂BiVO₆-rich interface and ZnO/ZnO interface, respectively. Accordingly, this study introduces a progressive method of manufacturing ZnO chip varistors by way of sintering ZZMn-based varistor under 900℃. However, to procure a higher reliability, an in-depth study on the multi-component varistors with double-layer grain boundaries should be executed.

Red phosphor in glasses (PiGs) for automotive light-emitting diode (LED) applications were fabricated with 620-nm CaAlSiN₃:Eu²⁺ phosphor and Pb-free silicate glass. PiGs were synthesized and mounted on high-power blue LED to make a monochromatic red LED. PiGs were simple mixtures of red phosphor and transparent glass powder. After being fabricated with uniaxial press and CIP at 300 MPa for 20 min, the green bodies were thermally treated at 550℃ for 30 min to produce high dense PiGs. As the phosphor content increased, the density of the sintered body decreased and PiGs containing 30% phosphor had a full sintered density. Changes in photoluminescence spectra and color coordination were studied by varying the thickness of plates that were mounted after optical polishing. As a result of the optical spectrum and color coordinates, PiG plate with 210 μm thickness showed a color purity of 99.7%. In order to evaluate the thermal stability, the thermal quenching characteristics were measured at temperatures of 30~150℃. The results showed that the red PIG plates were 30% more thermally stable compared to the AlGaInP red chip.

Transparent ZnS ceramics were synthesized by hydrothermal synthesis (180℃ for 70 h), and were sintered by a hot press process at 950℃. To confirm the optical properties of the ZnS ceramics after sintering for various sintering holding times, we performed X-ray diffraction analysis, scanning electron microscopy, and Fourier-transform-infrared spectroscopy. The ZnS nanopowders was found to be single-phase (cubic) without any hexagonal phase. However, the hexagonal phase is formed and increases in content with increasing sintering holding time. The density of the ZnS ceramics was above 99.7%, except for the unsintered one. The ZnS ceramics showed high transmittance (~70%) when sintered for more than 2 h.

Zinc sulphide (ZnS) nanoparticles were fabricated by hydrothermal synthesis at 180℃ for 12 h. Two kinds of ZnS powder (hydrothermal synthesized ZnS and commercial ZnS) were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) for phase and microstructure, respectively. The XRD patterns showed that all ZnS nanoparticles have a sphalerite (cubic) structure. The nanoparticles of two different ZnS powders were sintered by spark plasma sintering. The sintered ZnS were analyzed by XRD, SEM, and FT-IR. We found that the transmittance of the infrared region is highly dependent on the density and crystal structure of sintered ZnS and the purity of the starting ZnS powder.

We investigated the phase evolution, microstructure, and microwave dielectric properties of Na- and Zr-doped Ba(Mg_0.5W_0.5)O₃ [i.e., (Ba_1-2xNa_2x)(Mg_0.5-xZr_xW_0.5)O₃] ceramics. BaWO₄ as a secondary phase was observed in all compositions, and it increased as the dopant concentration increased. All specimens revealed a dense microstructure. For the composition of x=0.01, polyhedral grains were observed. As the dopant concentration increased, the densification and the grain growth were promoted by a liquid phase. The quality factor(Q×f₀) decreased remarkably, whereas the dielectric constant (ε_r) tended to decrease as the dopant concentration increased. The dielectric constant, quality factor, and temperature coefficient of the resonant frequency of the composition of x=0.01 sintered at 1,700℃ for 1 h were 18.6, 216,275 GHz, and -22.0 ppm/℃, respectively.

In this paper, in order to develop excellent composition ceramics for a piezoelectric energy- harvesting device, we synthesized 0.99(Na_0.52 K_0.443 Li_0.037)(Nb_0.883 Sb_0.08 Ta_0.037)O₃ + 0.01(Sr_0.95 Ca_0.05)TiO₃ + 0.3 wt% Bi₂O₃ + 0.3 wt% Fe₂O₃ + 0.3 wt% CuO (abbreviated as NKN-SCT) ceramics with different sintering times, using the ordinary solid-state reaction method. The effect of sintering time on the microstructure and piezoelectric properties was investigated. The ceramics with the sintering time of 7 h have the optimum values of the piezoelectric constant (d₃₃), piezoelectric voltage constant (g₃₃), planar piezoelectric coupling coefficient (kp), mechanical quality factor (Qm), and dielectric constant (εr): d₃₃= 314 [pC/N], g₃₃= 20.07 [10^-3 mV/N], kp = 0.442, Qm = 93, εr = 1,768, all being suitable for a piezoelectric energy-harvesting device.

This study focuses on the effects of doping Zn₂BiVO₆ and Co₃O₄ on the sintering and electrical properties of ZnO; where, ZZ consists of 0.5 mol% Zn₂BiVO₆ in ZnO, and ZZCo consists of 1/3 mol% Co₃O₄ in ZZ. As ZnO was sintered at about 800℃, the liquid phases, which are composed of Zn₂BiVO₆ and Zn₂BiVO₆-rich phases, were found to be segregated at the grain boundaries of sintered ZZ and ZZCo, respectively, which demonstrates that V_o^·(0.33~0.36 eV) are formed as dominant defects according to the analysis of admittance spectroscopy. As Co₃O₄ is doped to ZZ, the resistivity of ZnO decreases to ~38%, while donor density (N_d), interface state density (N_t), and barrier height (Φ_b) increase twice higher than those of ZZ, according to C-V characteristics. This result harbingers that ZZCo and its derivative compositions will open the gate for ZnO to be applied as more progressive varistors in the future, as well as the advantageous opportunity of manufacturing ZnO chip varistors at lower sintering temperatures below 900℃.

In this study, the effect of Tb inward diffusion on the magnetic properties of the Nd-Fe-B sintered magnets was studied. After sintering of the magnets, TbF₃ slurries were dip-coated on the surface of the samples, then heat-treatment was followed for TbF₃ diffusion. The element distribution in the magnets and the diffusion profiles of Tb ions were analyzed by an EPMA (electron probe micro-analyzer). Prolonged heat treatment resulted in a deeper diffusion length of Tb ions. Coercivity of the 1^st heat-treated sample showed 21.86 kOe, while that of the 1^st, 2^nd heat-treated and annealed sample revealed 34 kOe.

Convectional PZT based piezoelectric ceramics have to sinter at high temperature about 1,200℃ for their suitable electrical properties. However, some issues: low temperature sintering piezoelectric ceramic composition and reliable internal electrode, have recently attracted a great deal of interest as a highly efficient multi-layered piezoelectric ceramics. In order to optimize low temperature sintering conditions of thick-film PMN-PZ-PT ceramic, it was investigated sintering and piezoelectric properties according to the change of LiBiO₂contents. Thus, the superior piezoelectric properties were found at the pallet type PMN-PZ-PT optimized with low sintering processing at 925℃ including 7 wt% LiBiO₂sintering aid. Consequentially, we successfully manufactured thick-film PMN-PZ-PT ceramics, which had superior piezoelectric and dielectric properties, with 5 wt% of LiBiO₂sintering aid at temperature of 900℃.

Mo-Cu alloys have been widely used for heat sink materials, vacuum technology, automobile, and many other applications due to their excellent physical and electric properties. Especially, Mo-Cu composites with 5 ~ 20 wt.% copper are widely used for the heavy duty service contacts due to their excellent properties like low coefficient of thermal expansion, wear resistance, high temperature strength, and prominent electrical and thermal conductivity. In most of the applications, highly-dense Mo-Cu materials with homogeneous microstructure are required for better performance. In this study, Mo-Cu alloys were prepared by PBM (planetary ball milling) and SPS (spark plasma sintering). The effect of Cu with contents of 5~20 wt.% on the microstructure and thermal properties of Mo-Cu alloys was investigated.

We investigated the sintering behavior and piezoelectric properties of lead-free (K0.5Na0.5)NbO3 ceramics co-doped with excess 0.01 mol ZnO and x mol MnO2, where x was varied from 0 to 0.03. Excess MnO2 addition was found to retard the grain growth and densification during sintering. However, 0.005 mol MnO2 addition improved the piezoelectric properties of 0.01 mol ZnO added (K0.5Na0.5)NbO3 ceramics. The planar mode piezoelectric coupling coefficient, electromechanical quality factor, and piezoelectric constant d33 of 0.01 mol ZnO and 0.005 mol MnO2 added specimen were 0.40, 304, and 214 pC/N, respectively.

In this work, [Pb(Mg1/2W1/2)0.03(Ni1/3Nb2/3)x(Zr0.5Ti0.5)0.97-xO3-BiFeO3] (x=0.02 to 0.12) composition ceramics were fabricated by the conventional soild state reaction method and their microstructure and piezoelectric properties were investigated according to PNN substitution. The addition of small amount of BiFeO3, Li2CO3, and CaCO3 were used in order to decrease the sintering temperature of the ceramics. The XRD (x-ray diffraction patterns) of all ceramics exhibited a perovskite structure. The sinterability of PMW-PNN-PZT-BF ceramics was remarkably improved using liquid phase sintering of CaCO3, Li2CO3. However, it was identified from of the X-ray diffraction patterns that the secondary phase formed in grain boundaries decreased the piezoelectric properties. According to the substitution of PNN, the crystal structure of ceramics is transformed gradually from a tetragonal to rhombohedral phase. The x=0.10 mol PNN-substituted PMW-PNN-PZT-BF ceramics sintered at 920 showed the optimum values of piezoelectric constant(d33), piezoelectric figure of merit(d33·g33), planar piezoelectric coupling coefficient(kp) and density : d33=566 [pC/N], g33=29.28 [10-3mV/N], d33·g33=16.57 [pm2/N], kp=0.61, density=7.82 [g/cm3], suitable forduplex ultrasonic sensor application.

Sintering, microstructure, thermal conductivity and microwave dielectric properties of xLiF-(1-x)MgO ceramics (x=0.03-0.10 mol) were investigated. The high density was obtained in the specimens of x≥0.06, i.e., 0.04 LiF-0.96 MgO in mol, whereas the amount of 0.03 mol LiF was insufficient to densify. From the result that the contact flattening in the sintered specimen was observed, the densification occurred through the liquid-phase sintering. The specimen of x=0.06 showed the highest room-temperature thermal conductivity. Relative density, thermal conductivity, dielectric constant, and quality factor (Q x f) of the specimen for x=0.06 sintered at 900°C for 4 h were 97.8%, 39.2 Wm-1K-1, 9.45, and 14,671 GHz, respectively.

Sintering and microwave dielectric properties of Zn2-2xSil+xO4 (x=O-0.10) ceramics were investigated. The secondary phase of ZnO was observed in the specimen for x=O whereas SiO2 was detected in that for x=0.05. The composition of Zn2SiO4 might be close to x=0.02, i.e., Zn1.96Si1.02O4; the ratio of Zn/Si is 1.922. The insufficient grain growth was observed in the specimen of x=O. For the specimens of x≥0.05 , the grain growth sufficiently occurred through the liquid phase sintering. The value of quality factor of all specimens was dependent on the x value, i.e., the ratio of Zn/Si, whereas that of dielectric constant was independent. Relative density, dielectric constant, and quality factor (Q×f) of the specimen for x=0.05, i.e., Znl.9Si1.05O4, sintered at 1,400℃ were 96.5%, 6.43, and 115,166 GHz, respectively.

In this study, (1-x)Pb(Mg1/2W1/2)0.03(Ni1/3Nb2/3)0.09(Zr0.5Ti0.5)0.88O3 + xCeMnO3 (x= 0∼0.02) ceramics were prepared by Columbite precursor method. The phase structure, ferroelectric and piezoelectric properties were systematically investigated. It was found that PMW-PNN-PZT possessed superior electrical properties due to its composition close to the MPB (morphotropic phase boundary). Coercive electric field of 10.05 [kV/cm] and density of 7.88 [g/cm3] were obtained when the substitution amount of CeMnO3 is x=0.02. In contrast, specimens with x=0.01 showed the mechanical quality factor(Qm) of 1,091 and the electromechanical coupling factor(kp) of 0.613.

A comparative study has been attempted for microwave and conventional sintering of lead-freeBi0.5Na0.5TiO3(BNT)-based multilayer ceramic actuators(MLAs). It was found that microwave sintering(MWS) could be successfully applied to the co-firing of piezoceramic/AgPd MLAs with a 10 timesshorter firing cycle as well as 100℃ lower firing temperature (850℃) for sufficient densification thanconventional furnace sintering (950℃). Furthermore, MWS-derived specimens showed better electricfield-induced strain than that of CFS-derived specimens by effectively suppressing interdiffusions betweenceramic and electrode layers.

Thermoelectric materials have been the topic of intensive research due to their unique dual capability of directly converting heat into electricity or electrical power into cooling or heating. Bismuth telluride (Bi2Te3) is the best-known commercially used thermoelectric material in the bulk form for cooling and power generation applications In this work we focus on the large scale synthesis of nanostructured undoped bulk nanostructured Bi2Te3 materials by employing a novel bottom-up solution-based chemical approach. Spark plasma sintering has been employed for compaction and sintering of Bi2Te3 nanopowders, resulting in relative density of g·cm-3 while preserving the nanostructure. The average grain size of the final compacts was obtained as 200 nm after sintering. An improved NS bulkundoped Bi2Te3 is achieved with sintered at 400℃ for 4 min holding time.

We investigated the effect of excess CuO on the sintering behavior, ferroelectric, andpiezoelectric properties of lead-free Bi0.5(Na0.82K0.18)0.5TiO3 (BNKT) ceramics. The addition of excess CuOwas found to greatly contribute to the densification and grain growth, however, excess CuO over 3 mol%was precipitated at grain boundaries after sintering. BNKT with 1∼2 mol% CuO in excess sintered at975℃ showed piezoelectric properties comparable to those of unmodified BNKT sintered at 1,175℃. These results seem meaningful for its application to low cost multilayer actuators (MLAs) becauselow firing ceramics make it possible to apply less expensive base metals to the inner electrode ofMLAs.

(Ba0.85Ca0.15)(Ti0.9Zr0.1)O3+0.04wt% CeO2 lead-free ceramics were prepared by conventional oxide-mixed method and the effect of sintering temperature on microstructure, dielecrric and piezoelectric properties were investigated. Improved piezoelectric properties have been observed at 1,400℃ sintering temperature which show the optimal electrical properties, kp~0.412, d33~316 Pc/N, Qm~144, ~3,345 and Tc~85℃. These results show that the sintering temperature plays an important role in piezoelectric properties.

In this study, (Na0.525K0.443Li0.037)(Nb0.883Sb0.08Ta0.037)O3 + 0.10 wt%Bi2O3 + 0.35 wt%B2O3 ceramics were prepared by conventional soild-state sintering process. The specimens were sintered at temperature range from 1,060℃ to 1,100℃. XRD (X-ray diffractron), SEM (scanning electron microscope) were used to analyze the crystal structure and microstructural sproperties of specimens. And also, TO-T, TC were observed by the mesurement of temperature dependence of dielectric constant. Excellect physical properties of the piezoelectric constant d33= 170 pC/N, electromechanical coupling factor kp= 0.312, Tc= 315℃ were obtained, respectively, from the specimen sintered at 1,080℃.

(Na,K)NbO3-based piezoelectric ceramics were synthesized by a liquid phase sintering method with a selected glass frit. The effects of the content of the glass frit and the sintering temperature on the microstructure and the electrical properties of the samples were investigated. With the 0.1 wt% of glass frit content, (Na0.52K0.44Li0.06)(Nb0.84Ta0.10Sb0.06)O3 (NKL-NTS) ceramics showed the maximum values of the relative density (99.1%) and the electro-mechanical coupling factor (kp: 0.32) at the sintering temperature of 1,050℃. It might mean that a liquid phase sintering with a suitable glass frit having the lower flow temperature could improve the relative density and the piezoelectric properties.

PTCR ceramics of (Ba0.998Sm0.002)TiO3 + 0.001MnCO3 + xSiO2 (x=1, 2, 3, 4, 5, 6 mol%) were fabricated by solid state method. Disk samples of diameter 5 mm and thickness about 1mm were sintered at 1,290℃ for 2 h in reduced atmosphere of 5%H2-95%N2 followed by re-oxidation at 600℃ for 30 min. in 20%O2-80%N2.and their microstructures and electrical properties were investigated with SEM and Multimeter. The color of sintered samples was strongly dependent on SiO2 content showing that the color of samples with SiO2 of 1∼2 mol% was gray but that of samples with SiO2 of 4∼6 mol% was changed from gray to blue, which seems to be related with the reduction of samples due to the oxygen vacancies created during the sintering in reduced atmosphere. SiO2 content had a great influence on the microstructure and the electrical properties. With increasing SiO2 content, the grain size of samples increased and the resistivity as well as the resistivity jump (R285/Rmin) decreased, which is considered to be attributed to the resistivity change at grain interior and grain boundary due to the fast mass transfer through SiO2 liquide phase during the sintering. Samples with 2 mol% SiO2 has the resistivity of 202 Ω cm and the resistivity jump of 3.28. It is expected that SiO2 doped BaTiO3 based PTC ceramics can be used for multilayered PTC thermistor due to the resistance to the sintering in reduced atmosphere.

According to the composition of LTCC material, though it was thought that bulk defect which was made in forming process effects on the densification during the sintering, it was not reported systemically. In this study, we evaluated crystal structure, 3 point bending strength, hardness and microstructure of the samples by uniaxial pressing and tape casting using the commercial powders of the crystallizing glass and the glass/ceramic composite. In the case of glass/ceramic composite, Viox-001 powder with residual glass in the sintering, 3 point bending strength was similar regardless of forming process due to fill the bulk defect by residual glass. In the case of crystallizing glass, MLS-22, because glass phase was small in the sintering, glass did not fill the pore in the sample by uniaxial pressing process, therefore, the 3 point bending strength of it was 167 MPa. However, the 3 point bending strength of the sample by tape casting was 352 MPa and much higher. Meanwhile, crystal structure and hardness were similar regardless of forming process.