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In this work, 4CuO-TiO2-2Nb2O5 (CTN) composite oxide was added to ZnAl2O4 as sintering aid. XRD analysis revealed that trace amount of new phases formed in the ceramic samples with CTN, which might promote the low temperature sintering of ZnAl2O4 ceramics. The sample with 2 wt% CTN addition sintered at 1125 °C can achieve the highest thermal conductivity of 8.6 W/m·K and the lowest microwave dielectric loss of 3.59 × 10−4. The sintering temperature and thermal conductivity of ZnAl2O4 ceramics decreased while the dielectric constant and loss increased with the increase of the CNT contents. ZnAl2O4 ceramics can be sintered at a low temperature of 950 °C with the CTN content increasing to 10 wt%, which make it a potential material for the low temperature co-fired ceramics (LTCC) application. [ABSTRACT FROM AUTHOR]

A series of K2MnF6/KHF2 red phosphors were prepared through a low temperature way and their morphology and photoluminescence (PL) properties were investigated. The as-prepared phosphor shows an intense red emission with the strongest emission peak at 631 nm under a 454 nm excitation. Furthermore, the PL intensity and thermal stability performance, together with the quantum yields of the entitled phosphors excited under blue light are investigated and compared with relative commercial used phosphors. Finally, a bright LED with high color rendering performance of Ra = 86.8 was fabricated by using a 450 nm blue chip with YAG:Ce3+ and the as-prepared K2MnF6/KHF2 phosphor. The results indicate that the K2MnF6/KHF2 phosphors could facilitate potential application in the field of indoor lighting and backlighting. [ABSTRACT FROM AUTHOR]

The Li–Al–Si glass-ceramics were prepared by conventional glass-ceramic fabrication method. The influences of Na 2 O content on the sintering property, microstructure, and coefficient of thermal expansion were investigated. The results show that the coefficient of thermal expansion of LAS glass-ceramics can be tailored to match that of silicon by the addition of Na 2 O content. Na 2 O has a remarkable influence on the crystallinity of Li–Al–Si glass-ceramic. The coefficient of thermal expansion of Li–Al–Si glass-ceramic is thus tunable between that of glass phase and crystal phase. The Si–O bond length change in stretch vibration modes introduced by Na 2 O also contributes to the variation of coefficient of thermal expansion of the Li–Al–Si glass-ceramics. The coefficient of thermal expansion of the Li–Al–Si glass-ceramic with 1.5 wt% Na 2 O addition is about +3.34 ppm/°C at 350 °C and shows a good compatibility to that of silicon in a wide temperature range, which makes it a promising candidate for anodic bondable low temperature co-fired ceramic substrate applications. [ABSTRACT FROM AUTHOR]

The influence of CuO and B 2 O 3 addition on the sintering behavior, microstructure and microwave dielectric properties of Ti 1−x Cu x/3 Nb 2x/3 O 2 (TCN, x = 0.23) ceramic have been investigated. It was found that the addition of CuO and B 2 O 3 successfully reduced the sintering temperature of TCN ceramics from 950 to 875 °C. X-ray diffraction studies showed that addition of CuO-B 2 O 3 has no effect on the phase composition. The TCN ceramics with 0.5 wt% CuO-B 2 O 3 addition showed a high dielectric constant of 95.63, τ f value of + 329 ppm/°C and a good Q × f value of 8700 GHz after sintered at 875 °C for 5 h, cofirable with silver electrode. [ABSTRACT FROM AUTHOR]

The silver diffusion behavior in the low-temperature cofired ceramic (LTCC) comprising of borosilicate glass and alumina was investigated in this work. Transmission electron microscope (TEM) analysis revealed that silver ions diffused into LTCC materials through the glass phase. The addition of copper oxide in the LTCC materials can suppress the silver diffusion during the sintering process because of the enhanced crystallization of borosilicate glass, which leads to the quick increase in glass viscosity and retards the silver diffusion. Thermal dynamic analysis confirmed that the diffusion coefficient of silver in the copper-oxide-modified LTCC materials was largely reduced. [ABSTRACT FROM AUTHOR]

Abstract: A new type of low temperature co-fired ceramic (LTCC) composite, comprising β-Si3N4 whiskers and calcium aluminosilicate (CAS) glass, is introduced in this paper. We show that the CAS–Si3N4 composite can be densified at 775–850°C in air. The effect of β-Si3N4 whiskers incorporation on the thermal conductivity of this relatively low-temperature sintered CAS–Si3N4 composite is investigated. The thermal conductivity of the CAS glass is increased from 1.6 to 7.9W/mK after adding 35vol% of β-Si3N4 whiskers. Microstructure characterization and percolation model analysis indicate that the likely cause of increased thermal conductivity of the ceramic composites is the formation of thermal percolation networks. The crystallization of the CAS glass also contributes to the enhancement of thermal conductivity. The sample with the highest thermal conductivity shows a low relative dielectric constant of 7.1 and a dielectric loss of 0.006 at 1MHz. Such a ceramic composite with excellent thermal and dielectric properties is a promising LTCC substrate material. [Copyright &y& Elsevier]

Cs2Hg6S7is a promisingcompoundfor X-ray and γ-ray detection with a band gap of 1.63 eV. Anew method is reported for the synthesis of Cs2Hg6S7, along with growth studies of large Cs2Hg6S7crystals of dimensions up to several centimetersusing the Bridgman method. Our growth technique gives reproduciblecrystals with high resistivity (106ohm·cm). Crystalsgrown in this work exhibit figure of merit mobility lifetime (μτ) products comparable to commercial cadmiumzinc telluride (CZT). The Cs2Hg6S7crystals exhibit a strong photoluminescence signal at low temperaturein the range 1.50–1.75 eV. The thermal properties of the crystal,including the thermal expansion coefficient and the thermal conductivity,have been characterized. The nature of defects affecting the chargetransport properties in the as-grown Cs2Hg6S7crystals is discussed. The noncentrosymmetric character ofthe tetragonal crystal structure (space group P42nm) gives rise to a nonlinear optical secondharmonic generation response. [ABSTRACT FROM AUTHOR]

Abstract Two low temperature cofirable ceramic materials with thermal expansion coefficients (TEC) of 5.9 ppm/K and 6.6 ppm/K, respectively, were used in this work to introduce residual stress by the multilayer cofiring process. Theoretical calculation and finite element method (FEM) simulation were used to optimize the multilayered ceramic substrate composition design to obtain enhanced mechanical performance. Based on the failure condition of materials, the multilayered ceramic substrate has an optimal thickness ratio of the surface layers to the whole laminate (sandwich structure). Indentation method was used to measure the surface residual stresses and 3-point bending tests were used to measure the mechanical strength. Enhanced mechanical strength of 404 MPa can be obtained when the thickness ratio of surface layer to the whole laminate is 0.19. [ABSTRACT FROM AUTHOR]

The performance of NO 2 sensors with low operating temperature, high selectivity, and high sensitivity is of importance in the gas sensing field. In this work, porous Pr 2 Sn 2 O 7 /NiO heterojunction was fabricated by solid-state reaction. We analyzed the phase composition, morphology, and chemical composition of Pr 2 Sn 2 O 7 /NiO using X-ray diffraction, scanning electron microscope, chemical element mapping, transmission electron microscope, and X-ray photoelectron spectrometer. The gas sensing result reveals that the Pr 2 Sn 2 O 7 /NiO possesses significantly improved performance toward NO 2 than that of Pr 2 Sn 2 O 7. The fast response time of 2 s and high response value of 27.4 were realized in 250 ppm NO 2 at 180 ℃, promoting 17.5 times that in pure Pr 2 Sn 2 O 7. According to the Hall effect measurement, the carrier type of Pr 2 Sn 2 O 7 /NiO composite is dominated by electrons, so the resistance of Pr 2 Sn 2 O 7 /NiO increases once it is exposed to strong oxidizing gas. The heterojunction and Ni2+ replace Pr3+ reduce the sensor's operating temperature, providing a new strategy for developing a low-energy consumption device. Our work provides new insight into potential development for Pr 2 Sn 2 O 7 /NiO based heterojunction. [Display omitted] • Sensor was prepared via dry pressing and high temperature ceramic forming method. • PSO/NiO sensor exhibits a fast response (2 s) of 250 ppm NO 2 sensing performance at 180 °C. • The detection limit for NO 2 is 1 ppb, and the response value is 3.85. • PSO/NiO sensor has excellent gas sensing selectivity, stability and moisture resistance. [ABSTRACT FROM AUTHOR]

A wireless microfluidic sensor based on microwave reflection principle for liquid detection was introduced in this work. The presented sensor comprised a slot antenna and substrate integrated waveguide (SIW) resonator that is integrated with the microchannel using low temperature co-fired ceramic (LTCC) technology. The electromagnetic simulation has been carried out for the sensor structure optimization. The ethanol aqueous solution of 0-50% mole fraction and glucose aqueous solution of 0-600 mg/dL were used for demonstrating the liquid sensing performance of the proposed sensor, respectively. The wireless sensing signal was recorded and analyzed using a network analyzer with a robust interrogation antenna. As the result, the resonant frequency rises in a monotonic and linear manner as the increase of liquid concentrations. The normalized sensitivity of the sensor is 0.29% for deionized water, which is higher than that of the reported liquid sensors based on microwave method. The wireless microfluidic sensor provides a compact, rapid, and real-time monitoring method for liquid, and has wide application prospects in biomedicine and environment area. [Display omitted] • A novel wireless liquid sensor integrated antenna, resonator and microchannel was developed through LTCC technology. • The sensor presents very high sensitivity for the liquid detection resulting from the dielectric perturbation principle. • The linear relationship between the wireless signal and the complex permittivity of the liquid samples was revealed. [ABSTRACT FROM AUTHOR]