Sintering Behavior,Properties, and Applications of Co‐Fired Piezoelectric/Low Temperature Co‐Fired Ceramic (PZT‐SKN/LTCC) Multilayer Ceramics

Materials and processing conditions have been developed allowing co‐firing of fluxed PZT‐SKN materials with commercial low temperature co‐fired ceramic (LTCC) tapes. Previously, Pb(Zr_0.53, Ti_0.47)O₃–Sr(K_0.25, Nb_0.75)O₃ (PZT‐SKN) ceramics fluxed with 1 wt% LiBiO₂ and 1 wt% CuO addition were shown to sinter to high density at 900°C for 1 h, with a large d₃₃ piezoelectric coefficient of ~415 pm/V. Currently, the master sintering curve (MSC) approach has been used to study the densification behaviors of fluxed PZT‐SKN and LTCC tapes. Different sintering mechanisms for fluxed PZT‐SKN ceramics and LTCC materials are confirmed by analyzing the apparent activation energy (Q_a). Using knowledge gained from MSC results, an optimized sintering profile was developed. Multilayer PZT‐SKN/HL2000 (HeraLock^? Tape, Heraeus) stacks co‐fired at 900°C for 0.5 h maintain large piezoelectric coefficient (high field d₃₃ > 340 pm/V). EDS analysis reveal limited interdiffusion of Pb from PZT‐SKN layers in LTCC and the appearance of Al, Ca, and Si in the PZT‐SKN near the PZT‐SKN/LTCC interface. Further, elemental interdiffusion was not detected at the center of piezoelectric layer in PZT‐SKN/LTCC multilayer ceramics and no subsequent reduction in piezoelectric coefficient d₃₃ was observed. Finally, a piezoelectric microbalance with mass sensitivity of 150 kHz/mg was fabricated using the materials and methods developed.     

Low‐Temperature Co‐Fired Ceramic Substrates for High‐Performance Strain Gauges

Recent advances in the development of high gauge factor thin films for strain gauges prompt the research on advanced substrate materials. A glass ceramic composite has been developed in consideration of a high coefficient of thermal expansion (9.4 ppm/K) and a low modulus of elasticity (82 GPa) for the application as support material for thin‐film sensors. In the first part, constantan foil strain gauges were fabricated from this material by tape casting, pressure‐assisted sintering, and subsequent lamination of the metal foil on the planar ceramic substrates. The accuracy of the assembled load cells corresponds to accuracy class C6. That qualifies the load cells for the use in automatic packaging units and confirms the applicability of the low‐temperature co‐fired ceramic (LTCC) substrates for fabrication of accurate strain gauges. In the second part, to facilitate the deposition of thin‐film sensor structures to the LTCC substrates, pressure‐assisted sintering step is modified using smooth setters instead of release tapes, which resulted in fabrication of substrates with low average surface roughness of 50 nm. Titanium thin films deposited on these substrates as test coatings exhibited low surface resistances of 850 Ω comparable to thin films on commercial alumina thin‐film substrates with 920 Ω. The presented material design and advances in manufacturing technology are important to promote the development of high‐performance thin‐film strain gauges.     

Design and Fabrication of Transparent and Gas‐Tight Optical Windows in Low‐Temperature Co‐Fired Ceramics

Low‐temperature co‐fired ceramics (LTCC) enable the fabrication of microfluidic elements such as channels and embedded cavities in electrical devices. Hence, LTCC facilitate the realization of complex and integrated microfluidic devices. Examples can be applied in many areas like reaction chambers for synthesis of chemical compounds. However, for many applications it is necessary to have an optically transparent interface to the surroundings. The integration of optical windows in LTCC opens up a wide field of new and innovative applications such as the observation of chemiluminescent reactions. These chemical reactions emit electromagnetic radiation and thus offer a method for noninvasive detection. Thin glasses (≤500 μm) were bonded by thermocompression onto a LTCC substrate. As the bonding agent, a glass frit paste was used. Borosilicate glasses, fused silica as well as silicon were successfully bonded onto LTCC. To join materials with a large coefficient of thermal expansion mismatch (i.e., fused silica and LTCC), it is necessary to limit the heat input to the bond interface. Therefore, a heating structure was integrated into the LTCC substrate beneath the bond interface. This bonding process provides a gas‐tight optical port with a high bond strength.     

Low‐Temperature Co‐Fired Ceramics System for Light Absorbance Measurement

The article describes technology of the low‐temperature co‐fired ceramics (LTCC) structure that enables light absorbance measurements of liquid sample. The manufactured ceramic structure contains buried microfluidic channels. The structure consists of two co‐fired glass windows that separate the light source and detector from the test solution. A construction of an electronic measurement system is described as well. The signal from three light‐emitting diodes (LED)s — red, green, and blue — can be used in the absorbance measurements. The light intensity is measured by the TCS 3414CS (TAOS, Plano, TX) color detector. Optical properties of the fabricated microfluidic LTCC system is investigated with several concentrations of potassium permanganate (KMnO₄) in water solution. The system can be applied in microbiology for constant monitoring of bacterial growth.     

Preliminary Model and Technology of Piezoelectric Low Temperature Co‐fired Ceramic (LTCC) Uniaxial Accelerometer

Design procedure, technology and basic properties of a piezoelectric Low Temperature Co‐fired Ceramics (LTCC) accelerometer are presented in this paper. The sensor consists of a LTCC membrane with a seismic mass. Meggitt InSensor^® PZT thick film has been applied as the sensing material. Finite element method (FEM) has been used to analyze the impact of the sensor geometry (membrane thickness, membrane and seismic mass radii) and PZT thick film placement on basic properties (sensitivity and bandwidth) of the device. The LTCC process was optimized in order to create thin and planar ceramic membrane with relatively huge seismic mass. Selected properties of the sensor have been measured and compared with the simulated ones.     

Influence of Cold Low Pressure Lamination Parameters on the Joining of Low Temperature Co‐Fired Ceramics Green Tapes and Sintered Alumina Substrates

In this study, laminates consisting of sintered alumina substrates and green Low Temperature Co‐fired Ceramics (LTCC) tapes have been produced via Cold Low Pressure Lamination which is based on adhesive tapes for joining of layers at room temperature and pressures <5 MPa. The influences of lamination parameters such as temperature, pressure, and time on the quality of the green and sintered multilayer stack have been determined. If the bottom LTCC layer of an alumina–LTCC–LTCC laminate is metallized by screen printing defects such as crack formation can occur due to stress formation caused by constrained sintering. By adapting the lamination parameters, these stresses can be avoided. Another defect observed is cavities which form along the printed circuit lines. This type of defect is caused by the shrinkage of the circuit line width during firing; by reducing the height of the conductor line during screen printing, the cavity size can be reduced. In addition, different screen‐printed metallization layouts have been tested to determine the influence of line and spaces on the quality of sintered laminates.     

A Low Cost Large‐Area Solid Oxide Cells Fabrication Technology based on Aqueous Co‐Tape Casting and Co‐Sintering

Aqueous‐based tape casting is a low‐cost and environment friendly technology. In this paper, large‐area fuel electrode‐supported solid oxide cells (SOCs) were fabricated by this technology in conjunction with co‐sintering process. A 10 cm × 10 cm single cell with NiO/Zr_0.92Y_0.08O_2–δ fuel electrode, Zr_0.92Y_0.08O_2–δ electrolyte and La_0.6Sr_0.4Co_0.2Fe_0.8O_3+δ/Ce_0.9Gd_0.1O_2+δ air electrode has been successfully developed with improved electrode microstructure and hence the cell performance with the maximum power density of 534 mW cm^–2 at 850 °C with humidified H₂ as the fuel and air as the oxidant has been achieved. The optimal slurry formulations used in the fabrication of SOC were summarized for future reference purpose.     

Preparation of Ultrafine Silica-Germania Powders Using an Inductively Coupled Plasma Torch

Ultrafine silica-germania powders (<1 ×10^–7 m) were prepared by using an inductively coupled oxygen/argon plasma torch. The high-temperature plasma was generated inside a quartz tube through which oxygen/argon carrier gas and the tetrachlorides of silicon and germanium were injected. The powders were collected on a substrate.     

Determining Boron Speciation with an Inductively Coupled Plasma Optical Emission Spectrometer

A method of differentiating elemental B from oxidized B using inductively coupled plasma optical emission spectrometry (ICP‐OES) is presented. The method was developed and validated on weapons grade BKNO₃.     

电感耦合等离子体-质谱(ICP-MS)技术及其应用

文章介绍了电感耦合等离子体质谱仪(ICP-MS)的工作原理、仪器结构、分析特点,归纳了ICP-MS分析技术在不同领域的应用进展,探讨了ICP-MS联用技术的特点和发展趋势,并对其发展前景进行了展望。     

Sintering Behavior and Dielectric Properties of Ultra‐Low Temperature Fired Silver Molybdate Ceramics

Ag₂MoO₄ ceramic was prepared by using the solid‐state reaction method, which could be sintered at 450°C for 2 h, having a relative permittivity of 8.08, a Qf value of 17 000 GHz, and a temperature coefficient of resonance frequency about ?133 ppm/°C. Ag₂MoO₄ ceramic was chemically compatible with silver but reacted seriously with aluminum to form (Ag_0.5Al_0.5)MoO₄ during the sintering. The fitting of infrared spectra and the Shannon's additive rule were employed to study intrinsic dielectric behaviors of the ceramics at microwave region. Ionic displacive polarization and the electronic polarization contributed almost equally to the dielectric permittivity of the ceramic at microwave region. The Ag₂MoO₄ ceramics could be a good candidate for ultra‐low temperature co‐fired microwave devices.     

PNN‐PZN‐PMN‐PZ‐PT Multilayer Piezoelectric Ceramic with Low Sintering Temperature

Multilayer piezoelectric ceramic material with a composition of 0.1Pb(Ni_1/3Nb_2/3)O₃‐0.35Pb(Zn_1/3Nb_2/3)O₃‐0.15Pb(Mg_1/3Nb_2/3)O₃‐0.1PbZrO₃‐0.3PbTiO₃‐4 mol% excess NiO (0.1PNN‐0.35PZN‐0.15PMN‐0.10PZ‐0.3PT‐0.04NiO) was fabricated by a roll‐to‐roll tape casting process and co‐fired with Ag/Pd electrode at low temperature of 950°C. Their dielectric, piezoelectric, and ferroelectric properties were evaluated. The effective piezoelectric coefficient d₃₃ of the obtained multilayer piezoelectric material was 412 pm/V, while d₃₃ for the ceramic pellet was 503 pm/V. Piezoelectric displacement measurements revealed small displacement hysteresis for the multilayer material. The combined characteristics of the multilayer piezoelectric material using the selected composition showed the potential for high power, high strain, and high force actuation applications. In addition, as the composition had a tetragonal phase, which substantially deviated from morphotropic phase boundary (MPB), the excellent properties may be more tolerant to stoichiometric fluctuation, which can allow larger processing and composition window as desired for scalable production.     

A Novel Glass‐Ceramic with Ultra‐Low Sintering Temperature for LTCC Application

In this paper, the phase compositions and the dielectric properties of 3ZnO–2B₂O₃ glass‐ceramic prepared by solid‐state method were investigated. The X‐ray diffraction patterns show that all sintered samples consist of Zn₃B₂O₆ and α‐Zn(BO₂)₂. The dielectric properties changed significantly with the sintering temperature. After sintering at 650°C for 30 min, the glass‐ceramic exhibits optimum dielectric properties: a dielectric constant of 7.5 and a dielectric loss of 0.6 × 10^?3 at 10 MHz. The chemical compatibility with Ag electrode under the co‐fired process illustrates a potential application in low temperature co‐fired ceramic field for the glass‐ceramic.     

电感耦合等离子体发射光谱法测定焊锡中的锗

利用电感耦合等离子体发射光谱法测定焊锡中锗的含量,方法快速简便、准确度高、精密度好,考察了溶液酸度、高频功率对检测的影响,研究了共存元素间的相互干扰,优化了工作条件,用于实际样品的分析,结果令人满意。     

High‐Temperature Strength of Boron Suboxide Ceramic Consolidated by Spark Plasma Sintering

The spark plasma sintering (SPS) of B₆O ceramics using a highly crystalline boron suboxide powder with a low oxygen deficiency level is reported. The monolithic boron suboxide ceramic exhibited a room‐temperature strength of 300 ± 20 MPa, which is comparable to the strength of monolithic boron carbide. With increasing flexural test temperature, the strength of the boron suboxide ceramics increased to 450 MPa at 1400°C. The increase in strength with the temperature is associated with the unique microstructure of boron suboxide grains, which allows intergranular “brittle” fracture along subgrains even at 1400°C. This suggests that even higher strengths can be achieved.     

电感耦合等离子体质谱法测定原矿中钍的含量

原矿样品经过氧化钠熔融,三乙醇胺提取,在pH=2~3的酸度下,用PMBP-苯萃取钍,再用4 mol/L盐酸反萃取使钍与干扰元素分离。进行ICP谱仪测定钍的含量。     

电感耦合等离子体发射光谱法测定镁合金中的硼

采用电感耦合等离子体原子发射光谱法(ICP-AES)测定镁合金中硼的含量。准确称取一定量的镁合金样品于钢铁量瓶中,滴加(1+1)盐酸溶液,待剧烈反应完毕后,滴加过氧化氢加热溶解,溶解完后,将溶液定容至100m L容量瓶中,摇匀后,直接上机测试;优化全谱型ICP-AES分析条件测定镁合金中硼的含量,检出限为0.01mg/L。此方法可检测镁合金中硼的最低含量为0.001%,用5个自制样品进行测定(n=10),其结果符合要求。     

电感耦合等离子体发射光谱法和电感耦合等离子体质谱法测定天然绿色棉和染色绿色棉中20种元素含量

采用微波消解对天然绿色棉和染色绿色棉样品进行处理,通过电感耦合等离子体发射光谱法(ICP-OES)和电感耦合等离子体质谱法(ICP-MS)测定其B,Na,Mg,Al,P,K,Ca,Ti,V,Mn,Fe,Co,Ni,Cu,Zn,Ga,Rb,Sr,Mo,Ba 20种元素的含量。结果表明,与染色绿色棉相比,天然绿色棉中B,Mg,P,K,Ti,Mn,Rb,Sr,Mo元素含量显著偏高(概率P0.05),Na,Zn,Ba元素含量显著偏低(P0.05),采用聚类分析(最短距离法)对样品中20种元素含量进行处理,可正确判断天然绿色棉和染色绿色棉。     

电感耦合等离子发射光谱仪不确定度的评定

测量不确定度是对测量结果可信性、不效性的怀疑程度或不肯定程度,是定量说明测量结果质量的一个参数,其大小直接决定测量结果的可用性。介绍了电感耦合等离子体发射光谱仪(ICP-OES)的工作原理,依据JJF 1059-1999《测量不确定度评定与表示》和JJG 768-2005《发射光谱仪检定规程》,用美国热电公司的IRIS-intrepid型电感耦合等离子体发射光谱仪测量Zn、Ni、Mn、Cr、Cu、Ba多元素混合系列标准溶液,并通过对混合标准溶液检测数据的处理,进行电感耦合等离子体发射光谱仪测量结果的不确定度分析和评定。     

电感耦合等离子体质谱法测定饮用水中铅、镉

采用电感耦合等离子质谱法(ICP-MS)同时测定饮用水中的铅、镉,以建立简便,灵敏,准确的测定饮用水的方法。实验表明,方法的线性范围宽,线性相关系数均0.999,各元素的平均加标回收都在97.2%~106.8%之间,相对标准偏差在1.7%之内。测定的质控样均在范围,该方法简单,快速,灵敏,准确,适用于饮用水中重金属铅、镉的测定。