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This paper aims to select parameters such as temperature thermal stability and temperature coefficient of resistance (TCR) for Ni–P resistive alloys obtained by electroless metallization. Ni–P alloys are used in the manufacture of precision resistors characterized by TCR in the range of ± 10 ppm/K. The correlation of the technological parameters with the electrical properties of resistors enables the accurate prediction of the TCR resistors.

The Ni–P layers were obtained by a continuous process at about 373 K in a solution with the acidity of pH = 2 and then dried for two hours at 393 K. Subsequently, the Ni–P layer was stabilized for two hours in the temperature range of 453-533 K. Resistance was measured with an accuracy of 1 mΩ. TCR was determined with an accuracy of 1 ppm/K in the temperature range 298-398 K. In the next stage of the investigation, the increase in TCR of the Ni–P alloy was correlated with the increase in stabilization temperature. Scanning electron microscope images of the alloy surface were studied to assess grain sizes and to relate the average grain size with TCR values of resistive alloys. The X-ray diffraction analysis was performed to determine the crystallization temperature of Ni–P alloy.

The conducted investigation showed that the TCR increase in alloy is a linear function of stabilization temperature in the temperature range in which transition from amorphous phase to crystalline phases did not occur. TCR increase in Ni–P alloy arises from the increase of average size of grains resulting in decrease of scattering of electrons on grain boundaries. The analysis of alloy composition in chosen fragments of surface shows inhomogeneity growing with decreasing analyzed surface dimensions which proves that, before the stabilization, the structural arrangement of alloy is inconsiderable.

The obtained results are the first attempt to relate the morphology of surface with TCR of alloy and demonstration of linear dependence between an increase in TCR of amorphic Ni–P alloy and stabilization temperature of resistive layer. Such correlations are not described in available literature.

The work was aimed at preparation of green tapes based on a new material Bi_2/3CuTa₄O₁₂, to achieve spontaneously formation of an internal barrier layer capacitor (IBLC), fabrication of multilayer elements using low temperature cofired ceramics (LTCC) technology and their characterization.

The study focused on tape casting, lamination and co-sintering procedures and dielectric properties of Bi_2/3CuTa₄O₁₂ multilayer capacitors. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) studies of the ceramic elements were performed. Impedance spectroscopy was used for characterization of dielectric properties in the frequency range of 0.1 Hz to −2 MHz and in the temperature range from −55 to 400°C. DC conductivity was investigated in the temperature range 20 to 740°C.

SEM observations revealed a good compatibility of the applied commercial Pt paste with the ceramic layers. The EDS microanalysis showed a higher content of oxygen at grain boundaries. The dominant dielectric response, which was recorded in the low frequency range and at temperatures above 0°C, was attributed to grain boundaries. The dielectric response at low temperatures and/or high frequencies was related to grains. The fabricated multilayer capacitors based on Bi_2/3CuTa₄O₁₂ exhibited a high specific capacitance.

A new material Bi_2/3CuTa₄O₁₂ was applied for preparation of green ceramic tapes and utilized for fabrication of multilayer ceramic capacitors using the LTCC technology. This material belongs to the group of high permittivity nonferroelectric compounds with a complex perovskite structure of CaCu₃Ti₄O₁₂, that causes the spontaneously formation of IBLCs.

This paper aims to report on fabrication procedure and presents microstructure and dielectric behaviour of LiZn_0.92Cu_0.08PO₄ ceramic material with Li₂CO₃ as a sintering aid.

Substrates based on LiZn_0.92Cu_0.08PO₄ with Li₂CO₃ addition were prepared via solid-state synthesis, doping, milling, pressing and sintering. Characterization of the composition, microstructure and dielectric properties was performed using X-ray diffractometry, energy dispersive spectroscopy, scanning electron microscopy, impedance spectroscopy in the 100 Hz to 2 MHz range and time-domain spectroscopy in the 0.1–3 THz range.

Doped LiZnPO₄ ceramic, which exhibits a low dielectric constant of 5.9 at 1 THz and low sintering temperature of 800 °C, suitable for low temperature co-fired ceramics (LTCC) technology, was successfully prepared. However, further studies are needed to lower dielectric losses by optimising the doping level, synthesis and sintering conditions.

Search for new low dielectric constant materials applicable in LTCC technology and optimization of processing are essential tasks for developing modern microwave circuits. The dielectric characterization of doped LiZnPO₄ ceramic in the terahertz range, which was performed for the first time, is crucial for potential millimetre-wave applications of this substrate material.

The purpose of this study was to develop fabrication procedure of multilayer varistors based on doped ZnO and to investigate their microstructure and electrical properties.

Two ceramic compositions based on ZnO doped with Bi₂O₃, Sb₂O₃, CoO, MnO, Cr₂O₃, B₂O₃, SiO₂ and Pr₂O₃ were used for tape casting of varistor tapes. Multilayer varistors were prepared by stacking of several green sheets with screen printed Pt electrodes, isostatic lamination and firing at 1,050-1,100°C. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) studies were carried out to examine the microstructure and elemental composition of the varistors. Current-voltage characteristics were measured in the temperature range from −20 to 100°C.

The desired compact and fine-grained microstructure of multilayer varistors and nonlinear current-voltage characteristics were attained as a result of the applied fabrication procedure. The breakdown voltage of the varistors is 33-35 V and decreases slightly in the temperature range from −20 to 100°C. The nonlinearity coefficient changes from 14 to 23 with rising measurement temperature.

New improved formulations of varistor ceramic foils based on doped ZnO were developed using tape casting method and applied for fabrication of multilayer varistors with good electrical characteristics. The influence of temperature in the range from −20 to 100°C on the varistor parameters was studied.

The paper aims to report on fabrication procedure and present microstructure and dielectric behavior of multilayer porous low-temperature cofired ceramic (LTCC) structures based on glass-cordierite and glass-alumina.

The LTCC structures were created as multi-layered composites with dense external layers and inner layers with intentionally introduced porosity. Two preparation methods were applied – subsequent casting of both kinds of slurries and conventional isostatic lamination of dried green tapes arranged in the designed order. Optical microscope observations were carried out to analyze the microstructure of green and fired multilayer structures and pore concentration. To evaluate the adhesion strength of the composite layers, pull test was performed. Dielectric behavior of the composites was studied in the frequency range 50 kHz-2 MHz.

The fabricated porous LTCC structures showed dielectric constant of 3-5.6. The lowest dielectric constant was attained for glass-cordierite composite made by the conventional tape casting/lamination/firing method from slurry with 50 per cent graphite content. The samples prepared using multiple casting were of worse quality than those fabricated in conventional process, contained irregular porosity, showed tendency for deformation and delamination and exhibited a higher dielectric constant.

Search for new low dielectric constant materials applicable in LTCC technology and new methods of their fabrication is an important task for development of modern microwave circuits.

This paper aims to present the comparative study on the composition, microstructure and dielectric behavior of a group of new nonferroelectric high-permittivity A_2/3CuTa₄O₁₂ (A = Y, Nd, Sm, Gd, Dy or Bi) ceramics.

The materials under investigation were synthesized by solid-state reaction method and sintered at 1,120-1,230°C. Dielectric properties were investigated in the temperature range from −55 to 740°C at frequencies 10 Hz to 2 MHz. Microstructure, elemental composition and phase composition of the ceramics were examined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) methods. DC conductivity was studied in the temperature range 20-740°C.

XRD analysis revealed peaks corresponding to Cu₂Ta₄O₁₂ along with small amounts of secondary phases based on tantalum oxides. Impedance spectroscopic data and the results of SEM and EDS studies imply the spontaneous formation of internal barrier layer capacitors in the investigated materials. Two steps can be distinguished in the dielectric permittivity versus frequency plots. The low-frequency step of 1,000-100,000 is assigned to grain boundary barrier layer effect, while the high-frequency one of 34-46 is related to intrinsic properties of grains.

Search for new high-permittivity capacitor materials is important for the progress in miniaturization and integration scale of electronic passive components. The paper reports on processing, microstructure, microanalysis studies and dielectric properties of a group of novel nonferroelectric materials with the perovskite structure of CaCu₃Ti₄O₁₂ and the general formula A_2/3CuTa₄O₁₂, being spontaneously formed internal barrier layer capacitors.

The paper aims to present a research on the impact of the stabilization process of a thin metallic layer (Ni-P) produced on a ceramic surface (Al₂O₃) by means of electroless metallization on its electric parameters and structure. On the basis of the research conducted, the existence of a relationship between resistance (R) and the temperature coefficient of resistance (TCR) of the test structure with a Ni-P alloy-based layer and the temperature of stabilization was proposed.

Metallic Ni-P layers were deposited on sensitized and activated substrates. Metallization was conducted in an aqueous solution containing two primary ingredients: sodium hypophosphite and nickel chloride. The concentration of both ingredients was (50-70) g/dm³. The process lasted 60 min, and the metallization bath pH was kept at 2.1-2.2, whereas the temperature was maintained at 363 K. The thermal stabilization process was conducted in different temperatures between 453 and 623 K. After the technological processes, the resistance and TCR of the test structures were measured with a micro ohmmeter. The composition and the morphology of the resistive layer of the structures examined was also determined.

The dependence of the resistance on the temperature of the stabilization process for the temperature range 553 to 623 K was described using mathematical relationships. The TCR of test resistors at the same thermal stabilization temperature range was also described using a mathematical equation. The measurements show that the resistive layer contains 82.01 at.% of nickel (Ni) and 17.99 at.% of phosphorus (P).

The results associate a surface morphology Ni-P alloy with the resistance and TCR according to temperature stabilization. The paper presents mathematical relationships that have not been described in the literature available.

The purpose of the paper was to present a comparative study on the microstructure and magnetoelectric effect of new magnetoelectric composites based on TbFe₂ compound and Ni_0.3Zn_0.62Cu_0.08Fe₂O₄, CoFe₂O₄ ferrites as a magnetostrictive phase, Pb(Fe_1/2Ta_1/2)O₃ (PFT), Pb(Fe_1/2Nb_1/2)O₃ relaxors as a ferroelectric phase and polyvinylidene fluoride (PVDF) as piezoelectric phase.

The ceramic components of composites were prepared by the standard solid-state reaction method. The intermetallic compound TbFe₂ was prepared with an arc melting system with a contact-less ignition in a high purity argon atmosphere. The metal – ceramic – polymer composites were prepared in a container in which powder of PVDF were dissolved in N,N-dimethylformamide with continuous mixing and at the controlled temperature. Ceramic composites were prepared as bulk samples and multilayer tape cast and co-sintered laminates. The microstructure of the composites was investigated using scanning electron microscopy (SEM). The magnetoelectric effect of the composites was evaluated at room temperature by means of the dynamic lock-in method.

SEM analysis revealed a dense, fine-grained microstructure and uniform distribution of the metallic, ferrite and relaxor grains in the bulk composites. The SEM image for multilayer composite illustrates the lack of cracks or delaminations at the phase boundaries between the well-sintered ferrite and relaxor layers. For all studied composites, the magnetoelectric coefficients at a lower magnetic field increase, reaches a maximum and then decreases.

The progress in electronic technology is directly linked to advances made in materials science. Exploring and characterizing new materials with interesting magnetoelectric properties, in the rapidly growing field of functional materials, is an important task. The paper reports on processing, microstructure and magnetoelectric properties of novel magnetoelectric composites.

The aim of the present work was the characterization of a group of compounds with the perovskite‐type structure in respect of their applicability as thermistor materials.

Four compositions: La_0.7Sr_0.3Zr_0.5Co_0.2²⁺Co_0.3³⁺O₃, La_0.8Sr_0.2Ti_0.5Co_0.3²⁺Co_0.2³⁺O₃, La_0.4Sr_0.6Ti_0.3Fe_0.7O₃ and CaTi_0.8Co_0.2O₃ were synthesized by solid‐state reaction. Ceramic thermistor materials were sintered in the temperature range 1,300‐1,400°C. The synthesized powders were used for fabrication of thick film pastes and thermistors fired at 1,100‐1,250°C. Resistance‐temperature characteristics of the ceramic samples were studied in the range −55 to 800°C for the ceramic samples and 20‐600°C for thick films. Endurance tests at 300°C for 500 h were performed.

The developed NTC materials exhibited high temperature coefficients of resistivity, dense microstructure and good stability. The most advantageous characteristics have been shown by La_0.7Sr_0.3Zr_0.5Co_0.2²⁺Co_0.3³⁺O₃ and La_0.8Sr_0.2Ti_0.5Co_0.3²⁺Co_0.2³⁺O₃ thermistors. The highest Temperature coefficient of resistances for the ceramics were found in the temperature range from −55 to 180°C (−10.7 to −2.9 per cent/°C) and for the thick films in the temperature range 40‐300°C (−5.6 to −1.5 per cent/°C).

This work has been focused on preliminary choice of compositions appropriate for practical thermistor thick film applications. Elucidation of conduction mechanism of the investigated materials needs further complex studies of conductivity, nonstoichiometry, thermoelectric power, etc. as a function of temperature and oxygen partial pressure.

In this work, an attempt has been made to extend the typical range of NTC compositions and to fulfil the demand for improved stability of bulk and thick film thermistors at elevated temperatures.

The purpose of this paper is to characterize electrical parameters of amorphous Ni‐P resistive layers used for fabrication of precise resistors.

Ni‐P resistive layers were produced by the chemical process in water solution using Ni^2 + and H₂PO₂⁻ ions. The paper presents the results of the studies concerning the influence of bath acidity and conditions of thermal stabilization on the structure and temperature coefficient of resistance of Ni‐P alloy.

The temperature coefficient of resistance of amorphous Ni‐P layers was found to depend significantly on the parameters of chemical metallisation process. It was stated that the changes of through‐casing resistivity versus the acidity of technological solution have roughly parabolic characteristics.

In this paper, it was at first explained how the changes of the structure of Ni‐P resistive layers depend on their temperature coefficient of capacitance.