Electronic Ceramic Materials Research Articles

Discovery of the Naturally Occurring Pure CaTiO3 Cubic Perovskite from Tazheran Massif

As the parent compound of the perovskite-structured family and an analogue of davemaoite CaSiO3 in Earth’s lower mantle, CaTiO3 perovskite is widely used in electronic ceramic materials, immobilizing radioactive waste, and geosciences. Here we report the discovery of a natural pure CaTiO3 perovskite-C in calc-silicate veins in brucite marble in the Tazheran Massif, Russia. The mean composition of perovskite-C is 97 wt% total CaO and TiO2, and minor impurities of Na, Al, and Zr, yielding the chemical formula CaTi0.97Al0.01Na0.01Zr0.01O3. The cubic crystal structure—Pm3m, Z = 1: a = 3.8301 Å, V = 56.19 (2) Å3 (ρ = 4.019 g/cm3) has been refined to R1 = 0.0451. Compared with the cubic perovskite discovered in Israel, the cubic perovskite discovered in this study is very pure in Ca and Ti. The naturally occurring perovskite-C from Tazheran implies that the host skarn might have experienced high-temperature (> 1247–1374 °C) metamorphism and/or metasomatism at an early stage. Moreover, the discovery of natural perovskite-C also draws attention to considering crystal-structure-related matrix effects in the future of in situ U-Pb geochronology, especially using Tazh international perovskite standards.

The jump-like PTCR effect in Ca1-xYxCu3Ti4O12 ceramics hot quenched under high-pressure

The PTCR effect is an important application phenomenon in the ferroelectric BaTiO3 electronic ceramic materials. In this work, the PTCR effect is also found in high pressure (HP) hot quenched Ca1-xYxCu3Ti4O12 (CYCTO) ceramics. Compared with the pure CaCu3Ti4O12 (CCTO) ceramic synthesized under ordinary pressure (OP), the low temperature resistivity of HP CYCTO samples is about 3 orders of magnitude lower than that of untreated CCTO samples, showing an obvious PTCR effect. The transition temperature is close to 178 K for x = 0.2 sample. The analysis of crystal and magnetic structures shows that the crystal and magnetic structures of HP CYCTO samples do not change before and after the resistance transition. X-ray photoelectron spectroscopy showed that the concentration of oxygen vacancy defects in HP CYCTO is higher than CCTO. By analyzing the conduction behaviors of HP CYCTO samples, it suggests that oxygen vacancies and Y3+ ions may be the important donors for the decrease of low temperature resistivity of HP CYCTO samples. The results in this work have important reference value for the application of the electrical conduction behaviors in CCTO.

Giant dielectric response and relaxation behavior of Bi3+/W6+ co-doped TiO2 ceramics.

With the rapid development of electronic information technology, dielectric ceramics are widely used in the field of passive devices such as multi-layer ceramic capacitors. In this paper, (Bi2/3W1/3)xTi1-xO2 (BWTOx) ceramics with superior dielectric properties have been prepared by using a traditional solid-state method. Remarkably, at a (Bi2/3W1/3)4+ doping level of 0.01, a (Bi2/3W1/3)0.01Ti0.99O2 ceramic achieved a giant dielectric permittivity of ∼1.5 × 104 and a low loss tangent of ∼0.07 at 1 kHz, as well as a good temperature independence, which could satisfy the operating temperature standards for X9R capacitors. The abnormal dielectric relaxation in the low temperature region can be explained by the interface polarization. Data based on the complex impedance spectroscopy and X-ray photoemission spectroscopy results indicate that the colossal permittivity of BWTOx ceramics is mainly ascribed to the internal barrier layer capacitance effect. The findings of this work could provide valuable insights for achieving large dielectric constants and good temperature stability simultaneously in BWTOx and other related electronic ceramic materials.

Complex Oxides for Brain-Inspired Computing: A Review.

The fields of brain-inspired computing, robotics, and, more broadly, artificial intelligence (AI) seek to implement knowledge gleaned from the natural world into human-designed electronics and machines. In this review, the opportunities presented by complex oxides, a class of electronic ceramic materials whose properties can be elegantly tuned by doping, electron interactions, and a variety of external stimuli near room temperature, are discussed. The review begins with a discussion of natural intelligence at the elementary level in the nervous system, followed by collective intelligence and learning at the animal colony level mediated by social interactions. An important aspect highlighted is the vast spatial and temporal scales involved in learning and memory. The focus then turns to collective phenomena, such as metal-to-insulator transitions (MITs), ferroelectricity, and related examples, to highlight recent demonstrations of artificial neurons, synapses, and circuits and their learning. First-principles theoretical treatments of the electronic structure, and in situ synchrotron spectroscopy of operating devices are then discussed. The implementation of the experimental characteristics into neural networks and algorithm design is then revewed. Finally, outstanding materials challenges that require a microscopic understanding of the physical mechanisms, which will be essential for advancing the frontiers of neuromorphic computing, are highlighted.

Low dielectric loss, colossal permittivity, and high breakdown electric field in Al-doped Y2/3Cu3Ti4O12 ceramics

The miniaturization and high capacitance of electronic components are driving the development of high-performance electronic ceramic materials. In this work, we design a new strategy to achieve satisfactory dielectric properties with low loss, colossal permittivity, and a high breakdown electric field (Eb) in Al-doped Y2/3Cu3Ti4O12 (YCTO) ceramics prepared by a solid-phase synthesis method. The dielectric loss decreased with Al doping in the YCTO. The dielectric constant and the Eb were improved upon Al doping. With Al doping levels of 0.03 and 0.05, Y2/3Al0.03Cu2.97Ti4O12 and Y2/3Al0.05Cu2.95Ti4O12 ceramics displayed, respectively, a suppressed loss tangent of about 0.028 and 0.031, a high dielectric constant of approximately 9540 and 11792, and an Eb of approximately 4.32 and 4.54 kV/cm. The improved dielectric properties of the produced ceramics were closely linked to enhanced grain boundaries resistance. This study explores the physical mechanism behind the high performance of the YCTO-based ceramics, and also provides theoretical support for the application of devices comprising YCTO and related materials.

International Conference on Electronic and Advanced Materials 2021

The International Conference on Electronic and Advanced Materials (ICEAM) 2021 was held online on the 2nd November 2021 streaming from Digital Management and Development Centre, Universiti Malaysia Perlis (UniMAP). This conference was organized by the Center of Excellence Geopolymer & Green Technology (CEGeoGTech), UniMAP, with Tin Solder Technology Research Group (TSTRG) MALAYSIA and The Electronics Packaging Research Society (EPRS) as co-organizer. The conference was also sponsored by the Tin Industry (R&D) Board. The conference was held virtually in order to follow the standard operation procedure imposed by the Malaysian government due to the COVID-19 movement control order and travel restriction.The conference serves as the best platform for sharing and exchanging ideas on Advanced Materials topics such as electronic materials, ceramic materials and geopolymer, bio-materials, polymers and rubber, and composites. The conference aimed to provide a platform for scientists, researchers, and students in the related field to discuss current research progress, challenges, and practical solutions that could be adopted to keep abreast in this challenging world. The program provides networking and cooperation amongst academicians, scientists, researchers, and engineers from the materials sciences and engineering fields.List of Organizing committee is available in this pdf.

First principles analysis of impurities in silicon carbide grain boundaries

Silicon carbide is an important structural and electronic ceramic material that finds many uses in a wide variety of applications that require stability at extreme conditions. In this study, we provide a detailed investigation of the formation energies of point defects and the stability of a wide variety of dopants in bulk cubic silicon carbide (3C-SiC) and in 3C-SiC grain boundaries (GBs) using first principles methods and a detailed charge distribution analysis. We also determine the driving force (segregation energies) of these dopants towards GBs. Our results show that smaller, more electronegative elements such as oxygen and nitrogen occupy carbon substitutional sites whereas larger transition metals such as molybdenum and rare earth elements such as cesium, substitute for silicon sites in SiC. Such dopants tend to migrate to more open spaces as provided in the Σ9 GB. This suggests that Σ9 GB is more effective in pinning the defect centers as compared to Σ3 GB. These findings provide the chemical landscape for defect engineering through which doped 3C-SiC can be designed for targeted materials development purposes.

Effects of Dy2O3 on the Electrical Properties of a (Nb2O5-Dy2O3-SiO2) Co-doped TiO2 Varistor

Rutile-TiO2 ceramics are very promising electronic ceramic materials which can be applied in varistors because of their good electrical properties. In this work, Dy2O3 was used to improve the electrical properties of a TiO2 varistor doped with 0.60 mol.% Nb2O5 and 0.30 mol.% SiO2. Results showed that the TiO2 varistor doped with 0.30 mol.% Dy2O3 possessed optimal electrical properties with good nonlinear coefficient ( $$ \alpha = 5.7 $$ ), very low breakdown voltage ( $$ E_{\text{B}} = 1.34\;{\text{V}}\,{\text{mm}}^{ - 1} $$ ) and colossal dielectric constant ( $$ \varepsilon_{\text{r}} = 8.01 \times 10^{5} $$ ). The microstructural analysis showed that after the incorporation of Dy2O3 into the TiO2 varistor, the grains tended to be more semiconducting due to the defect carriers derived from the substitution of Dy3+ for Ti4+. Meanwhile, the moderate dopant of Dy2O3 also increased the grain size and narrow grain boundary. Consequently, the breakdown voltage decreased, while the nonlinear coefficient and dielectric constant improved.

Strategic Thinking on the Development of Electronic Ceramic Technology in China

Electronic ceramics are a type of new materials of strategic significance. They are the core materials of passive electronic components and an important technology frontier in the electronic information technology field. As the electronic information technology develops toward integration, intelligence, and miniaturization, passive electronic components have become a bottleneck restraining the development of electronic component technology. Therefore, the strategic position of electronic ceramic materials and their processing technologies is increasingly prominent. The field of electronic ceramic materials and components has formed a good industrial technology foundation in China. However, its competitiveness is still insufficient in high-end materials and components, and some key material, process, and equipment technologies are controlled by other countries. Facing the new situation, it is urgent to increase R & D investment, rationalize the system and mechanism, and strengthen the independence and innovation of the industrial chain.

Oxidation characteristics of MgF2 in air at high temperature

High temperature oxidation properties of MgF2 in air were studied. The changes of phase composition, macro surface morphology, weight and elemental composition of MgF2 samples with temperature were investigated by using XRD, EDS and gravimetric analyses. The results show that the oxidation reaction of MgF2 converted to MgO occurred at high temperature, and the reaction was accelerated by the increase of temperature and the presence of impurities. This result clarifies the understanding of the high temperature oxidation behavior of MgF2 in air, and provides a theoretical basis for the reasonable application of MgF2 in optical coating materials, electronic ceramic materials and magnesium melt protection.

Experimental investigations on super-smooth polishing of strontium titanate based ceramics substrates

Strontium titanate (SrTiO3) is a new type of multi-function electronic ceramic material. SrTiO3 ceramic substrates with a high dielectric constant can be obtained by non-pressurised sintering using ultrathin blanks, which result in the characteristics of thin, soft, brittle and warped. So that SrTiO3 ceramics substrates need to be polished to improve surface quality and dimensional precision before application. In this research, polish experiments with various processing parameters on the surface roughness, the material removal rate and the surface morphologies of SrTiO3 ceramic substrates were conducted. The results show that the SrTiO3 ceramic substrate with a highest quality surface was obtained in the condition: employing a brown polyurethane pad to polish the substrates at a polishing velocity of 45 r/min. Meanwhile, the slurry flow rate, the concentration of the polishing slurry and the polishing pressure were 20 ml/min, 4 wt% and 15.043 kPa, respectively, which rates with an overall and a partial surface roughness of Ra 0.01 µm and Ra 4 nm, respectively. While some new micro-scratches were generated on the surface of the SrTiO3 ceramics substrate in the polishing process because the embedding and scratching of abrasive particle led to expose the inherent pores and grain boundaries.

Research Development of Preparation Technology of BaTiO3 Nano-Power

Barium titanate (BaTiO3) used a strong dielectric materials, piezoelectric materials and ferroelectric materials, which is a kind of important electronic ceramic materials. With the miniaturization of electronic components, miniaturization, thin layer, nanosized barium titanate powder become an inevitable developing trend of barium titanate dielectric ceramics material. Some recent new progress for synthesis of barium titanate at home and abroad are summarized, the commentaries are made on the preparation process about advantages or disadvantages. Meanwhile, the analysis is made on the developing trend. Supercritical fluid extraction method have simple process, high extraction efficiency, no organic solvent residual, products of good quality, no environmental pollution, and so on. Research of BaTiO3nanopower may become an important direction of the field in the future.

Effect of two different superstrate layers on bismuth titanate (BiT) array antennas.

The microwave industry has shown increasing interest in electronic ceramic material (ECM) due to its advantages, such as light weight, low cost, low loss, and high dielectric strength. In this paper, simple antennas covered by superstrate layers for 2.30 GHz to 2.50 GHz are proposed. The antennas are compact and have the capability of producing high performance in terms of gain, directivity, and radiation efficiency. Bismuth titanate with high dielectric constant of 21, was utilized as the ECM, while the superstrate layers chosen included a split ring resonator and dielectric material. The superstrate layers were designed for some improvement in the performance of directivity, gain, and return loss. The proposed antennas were simulated and fabricated. The results obtained were small antennas that possess high gain and high directivity with 360°, omni-directional signal transmission that resonant types of conventional dipole antenna cannot achieve. The gain of the antenna with the superstrate layer was enhanced by about 1 dBi over the antenna without a superstrate layer at 2.40 GHz.

Amorphization Induced by Focused Ion Beam Milling in Metallic and Electronic Materials

Focused ion beam (FIB) milling using high-energy gallium ions is widely used in the preparation of specimens for transmission electron microscopy (TEM). However, the energetic ion beam induces amorphization on the edge of specimens during milling, resulting in a mischievous influence on the clearness of high-quality transmission electron micrographs. In this work, the amorphization induced by the FIB milling was investigated by TEM for three kinds of materials, metallic materials in bulk shape, and semiconductive and electronic ceramic materials as a substrate for the deposition of thin films.

THE APPLICATION OF STEREOLOGY METHOD FOR ESTIMATING THE NUMBER OF 3D BaTiO3 – CERAMIC GRAINS CONTACT SURFACES

Methods of stereological study are of great importance for structural research of electronic ceramic materials including BaTiO3-ceramic materials. The broad application of ceramics, based on barium-titanate, in advanced electronics nowadays demands a constant research of its structure, that through the correlation structureproperties, a fundamental in the basic materials properties prognosis triad (technology-structure-properties), leads to further prognosis and properties design of these ceramics. Microstructure properties of BaTiO3- ceramic material, expressed in grains' boundary contact, are of basic importance for electric properties of this material, particularly the capacity. In this paper, a significant step towards establishing control under capacitive properties of BaTiO3-ceramics is being done by estimating the number of grains contact surfaces. Defining an efficient stereology method for estimating the number of BaTiO3-ceramic grains contact surfaces, we have started from a mathematical model of mutual grains distribution in the prescribed volume of BaTiO3-ceramic sample. Since the real microstructure morphology of BaTiO3-ceramics is in some way disordered, spherical shaped grains, using computer-modelling methods, are approximated by polyhedra with a great number of small convex polygons. By dividing the volume of BaTiO3-ceramic sample with the definite number of parallel planes, according to a given pace, into the intersection plane a certain number of grains contact surfaces are identified. According to quantitative estimation of 2D stereological parameters the modelled 3D internal microstructure is obtained. Experiments were made by using the scanning electronic microscopy (SEM) method with the ceramic samples prepared under pressing pressures up to 150 MPa and sintering temperature up to 1370°C while the obtained microphotographs were used as a base of confirming the validity of presented stereology method. This paper, by applying computer stereology method for estimating the number of grains contact surfaces, makes possible a further insight into the microstructure of BaTiO3-ceramics with the final aim to design new properties of electronic materials based on barium - titanate ceramics.

ChemInform Abstract: Coordination Compounds of Aluminum as Precursors to Aluminum Nitride

Abstract Two different systems have been examined as potential sources of aluminum nitride, an important electronic and structural ceramic material. Cyclic organoaluminum amides obtained as intermediates in the thermolysis of trialkylaluminum : ammonia Lewis acid-base complexes have been used to obtain AlN powder and as precursors for the chemical vapor deposition of AlN films. The structures of two of these intermediates were determined by single-crystal XRD and the kinetics and thermodynamics of their formation and thermal decomposition reactions were also studied. The second system employs ethylenediamine as the Lewis base in combination with the R 3 Al (R = Me, Et) compounds. A 2:1 ratio of Et 3 Al with en yields a hydrocarbon-soluble, polymeric amide on thermolysis, which can be used to prepare AlN films by solution coating followed by pyrolysis in NH 3 . Lower proportions of R 3 Al to en, on thermolysis, lead to the formation of R m Al(en-2H) n cluster species that contain 5- and 6-coordinated Al atoms chelated and bridged by en-2H ligands. On further heating, these cluster species apparently go on to form cross-linked, insoluble, polymeric networks through condensation reactions involving the multiple N-H and R-Al groups on the periphery of the cluster molecules. The structures of two of these novel Al-en cluster compounds were determined by single-crystal XRD.

Structural studies of Ba1-xLaxTiO3 using X-ray absorption near-edge spectroscopy

La-doped barium titanate (Ba1-xLaxTiO3) is an important electronic ceramic material used in a wide variety of applications including in multilayer capacitor, transducers, ferroelectric thin film memories, and positive temperature coefficient resistor (PTCR). In this work, we investigated the changes of the local atomic structure around barium and titanium ions of Ba1-xLaxTiO3 compounds prepared by solid state reaction using X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). The X-ray Absorption Near-Edge Structure (XANES) spectra at the Ti K-edge (4966 eV) and Ba LIII-edge (5247 eV) were analyzed. Our findings suggest that La3+ doping can modify the degree of covalency of the Ti-O bonds, but cause no change in the BaTiO3 unit cell volume and the atomic coordinate around Ti4+, Ba2+ions.

Cr을 첨가한 ZnO의 결함과 입계 특성

In this study, we investigated the effects of Cr dopant (1.0 at% <TEX>$Cr_2O_3$</TEX> sintered at <TEX>$1000^{\circ}C$</TEX> for 1 h in air) on the bulk trap (i.e. defect) and interface state levels of ZnO using dielectric functions (<TEX>$Z^*$</TEX>, <TEX>$M^*$</TEX>, <TEX>$Y^*$</TEX>, <TEX>$\varepsilon^*$</TEX>, and <TEX>$tan{\delta}$</TEX>), admittance spectroscopy (AS), and impedance-modulus spectroscopy (IS & MS). For the identification of the bulk trap levels, we examine the zero-biased admittance spectroscopy and dielectric functions as a function of frequency and temperature. Impedance and electric modulus spectroscopy is a powerful technique to characterize grain boundaries of electronic ceramic materials as well. As a result, three kinds of bulk defect trap levels were found below the conduction band edge of ZnO in 1.0 at% Cr-doped ZnO (Cr-ZnO) as 0.11 eV, 0.21 eV, and 0.31 eV. The overlapped defect levels (<TEX>$Zn^{..}_i$</TEX> and <TEX>$V^{\cdot}_0$</TEX>) in admittance spectra were successfully separated by the combination of dielectric function such as <TEX>$M^*$</TEX>, <TEX>$\varepsilon^*$</TEX>, and <TEX>$tan{\delta}$</TEX>. In Cr-ZnO, the interfacial state level was about 1.17 eV by IS and MS. Also we measured the resistance (<TEX>$R_{gb}$</TEX>) and capacitance (<TEX>$C_{gb}$</TEX>) of grain boundaries with temperature using impedance-modulus spectroscopy. It have discussed about the stability and homogeneity of grain boundaries using distribution parameter (<TEX>$\alpha$</TEX>) simulated with the Z"-logf plots with temperature.

Electric force microscopy investigations of barrier formations in ZnO-based varistors

The well known metal-oxide varistors (MOVs) are polycrystalline electronic ceramic materials whose electrical behavior is dominated by their grain boundaries. ZnO-based varistors are MOVs whose nonlinear properties are characterized by an electrical resistance that decreases as the applied voltage field increases. The objective of this work was to image the Schottky barriers in ZnO doped with 0.5 mol.% Cu and x wt.% G (G is a frit and x = 0, 1 and 5%). The frit is used to form a glassy insulating layer around grain boundaries. Samples were sintered at 850 °C and the microstructures were analyzed by atomic force microscopy (Nanoscope IIIa, VEECO Instruments). Electric force microscopy (EFM) experiments were conducted to map the electric field distribution on the surface of CuO–ZnO-based varistors. The formation of Schottky barriers was observed and their width measured.

Strategy for Generation and Management of Intellectual Property in Small and Medium Enterprises (SMEs) with Particular Reference to Glass and Ceramics

Ceramic industry includes refractories, whitewares and porcelains, glasses of various types, electronic ceramic materials and several others which are normally products for industrial use and occasionally for domestic use. Ceramic materials are widely used throughout the world and its industries have taken a dominant position in the global market. Though Indian ceramic industries were in a remarkable position in the world in the past, they are now economically and competitively suffering and are struggling hard to survive particularly after globalization. The principal reason for such a state of the industry is the lack of awareness of Intellectual Property Rights issues. In the present paper, strategies for generation and management of intellectual property in SMEs with particular reference to glass and ceramics have been discussed in the background of the Indian position in the local and international market.