Glass-ceramic Substrates Research Articles

Thermovoltaic response in two-layered thin-film zinc oxide structures

A method of measuring the thermovoltaic effect in heterogeneous media with gradient doping impurity distributions producing gradient carrier distributions has been proposed. Iron doped zinc oxide specimens have been produced using ion beam sputtering on thin foil tantalum substrates for thermovoltaic effect measurements, glass-ceramic substrates for Hall measurements and silicon substrates for structural study. The doping impurity concentration хFe in the specimens has been varied from 0.34 to 4.18 at.%. X-ray phase analysis has shown that all the specimens have a hexagonal zinc oxide crystal structure. The films have preferential [002] orientation. The carrier concentration in the experimental specimen layers according Hall data obtained on an ECOPIA 5500 measurement system in a 0.5 T DC magnetic field has varied in the 1016–1020 cm-3 range. The specimens have an n-type conductivity. Thermovoltaic measurements have been carried out for two-layered iron doped zinc oxide specimens with different carrier and iron doping impurity concentrations using the method proposed. The maximum thermovoltaic response (U ~ 80 μV) has been observed in the two-layered thin-film specimen with the carrier concentration difference between the layers (Δn ≈ 2∙103 cm-3). The observed saturation of the thermovoltaic response has been attributed to the establishment of dynamic equilibrium between carrier diffusion from the high carrier concentration layer to the low carrier concentration layer and carrier drift due to internal electric field.

Magnetic properties and magnetoresistance of hybrid multilayer nanostructures {[(Co40Fe40B20)34(SiO2)66]/[ZnO]}n

The structural, electrical, magnetic, magneto-optical properties and magnetoresistance of {[(Co40Fe40B20)34(SiO2)66]/[ZnO]}n multilayer structures, where n = 50 is the number of bilayers (Co40Fe40B20)34(SiO2)66 nanocomposite and ZnO have been studied. The thicknesses of (Co40Fe40B20)34(SiO2)66 nanocomposite layers as well as ZnO spacers were varied in a wide range. The samples were synthesized by ion-beam sputtering onto glass ceramic substrates. The (Co40Fe40B20)34(SiO2)66 composite have an amorphous structure and the semiconductor ZnO interlayers have a hexagonal crystalline structure with the p63mc symmetry group. The nanocomposite layers containing a ferromagnetic component far from the percolation threshold are in a superparamagnetic state. The presented in the paper data of magnetization, magneto-optical transverse Kerr effect and magnetoresistance indicates that long-range ferromagnetic order does not form down to 77 K both for references ZnO films and studied multilayers with thin and thick ZnO interlayers. An increase in the magneto-optical signal in multilayers compared to references (Co40Fe40B20)34(SiO2)66 composite films has been detected at 1.2 eV. The magnetoresistance of {[(Co40Fe40B20)34(SiO2)66]/[ZnO]}n multilayers with thick (>32 nm) ZnO interlayers is lower than in reference (Co40Fe40B20)34(SiO2)66 nanocomposite, while at thin ZnO interlayers magnetoresistance is significantly higher and reaches 12 % at temperatures of 77 К. Possible mechanisms of ferromagnetic and antiferromagnetic ordering, enhancement of the magneto-optical response and magnetoresistance in {[(Co40Fe40B20)34(SiO2)66]/[ZnO]}n multilayer nanostructures are discussed.

Characteristics of a CaO–B2O3–SiO2–Al2O3–ZnO-based sandwich substrate and its dielectric properties in the 5G millimeter-wave band

In this study, a 34.5CaO–23B2O3–33.5SiO2–6Al2O3–3ZnO (CBSAZ) glass-ceramic substrate was prepared using a sol–gel method. A porous CaO–B2O3–SiO2–Al2O3–ZnO layer (CBSAZ0.5C) with a porosity of 72.6 % and thickness of 365 μm was inserted between two ∼120 μm thick dense CBSAZ layers to form a tri-layer substrate (CBSAZ/CBSAZ0.5C/CBSAZ). The dielectric constants (εr) and dielectric losses (tanδ) of the dense CBSAZ substrate at 20 and 60 GHz were 6.90 and 0.029, respectively, and 6.96 and 0.017, respectively. These values were almost independent of frequency. In contrast, the εr and tanδ values of the CBSAZ/CBSAZ0.5C/CBSAZ sandwich substrate at 20 and 60 GHz were 3.59 and 0.022, respectively, and 3.11 and 0.020, respectively. Thus, the εr value of the CBSAZ/CBSAZ0.5C/CBSAZ sandwich substrate was significantly lower than that of the CBSAZ substrate, whereas the tanδ and κ values of the CBSAZ/CBSAZ0.5C/CBSAZ and CBSAZ substrates were similar.

A novel Gd2O3–Al2O3–SiO2 glass-ceramics substrate material with comprehensive performance

A novel Gd2O3–Al2O3–SiO2 glass-ceramics (GAS GCS) for substrate application was prepared using the melt-quenching method. The present study pay attention to investigate the crystallization and sintering behaviors, phase compositions, micromorphology, dielectric and mechanical properties of GAS glass-ceramics. An appropriate amount of Gd2O3 diminished the glass viscosity while enhancing structural stability, thereby reducing the activation energy for crystallization and sintering. This contributed to the GAS GCS achieve dense microstructure and high crystallinity. X-ray diffraction (XRD) and Raman spectroscopy analyses confirmed the presence of high-density crystal phases, namely Gd2SiO5 and Gd2Si2O7, which significantly contribute to the enhanced density of the samples. Moreover, a positive correlation was observed between the dielectric constant and crystallinity. Notably, the GAS GCS composition of 41 wt% Gd2O3-21.3 wt% Al2O3-37.7 wt% SiO2 exhibited optimal properties, including a flexural strength of 243.4 MPa, Vickers hardness of 7.77 GPa, elastic modulus of 154.02 GPa, coefficient of thermal expansion of 5.9 × 10−6/°C, dielectric constant of 7.43, and dielectric loss of 4.05 × 10−3. These outstanding characteristics position it as a promising candidate for substrate materials.

Bulk glass-ceramic composites and ULTCC substrates for microwave and millimetre-wave applications

In this study, a new ultra-low-temperature co-fired ceramic (ULTCC) glass-ZnO-SiO2-B2O3CeO2−MgO-Al2O3 composite was developed and its applicability as a dielectric substrate in emerging high-performance communication technologies in the microwave and millimetre-wave frequency ranges was investigated. The novel material composition enables achieving good sinterability at a low fabrication temperature of 470 °C. Extensive studies have been conducted on the microstructure, porosity, water absorption, surface roughness, and thermal expansion coefficient. Following this analysis, the dielectric properties of the bulk glass-ceramic composites and the final ULTCC substrates were characterised. These measurements were conducted within a broad frequency range of 5 GHz–1.1 THz using split-post dielectric resonators, a Fabry-Perot open resonator, and a time-domain spectrometer, resulting in quasi-continuous frequency characteristics of the complex permittivity. Furthermore, the fabricated ULTCC substrates were subjected to surface-wise measurements, which provided 2D maps of the dielectric properties as qualitative and quantitative measures of the uniformity and quality of the material.

Investigation of sensing performances of thick-film resistors sintered on fluorophlogopite glass-ceramic substrates

Strain gauges made of thick-film resistors (TFRs) offer a promising solution for monitoring the structural health of civil engineering projects, owing to their exceptional durability and stability. To address the issue of strain mismatch between alumina substrates and concrete materials, fluorophlogopite glass-ceramic (FGC), which has a low elastic modulus and good machinability, was utilized as a substrate for thick-film resistors. Compatibility between resistor pastes and substrates should be considered, as the substrate can significantly impact the performance of thick-film resistors. TFRs with varying concentrations of RuO2 were screen printed and fired at different temperatures on both FGC and 96% Al2O3 (as a control) substrates. The sheet resistivity, temperature coefficient of resistance (TCR), and gauge factor (GF) of TFRs were evaluated. The strain sensing performances of TFRs on FGC evaluated under compressive loading. The results indicate that TFRs on FGC substrates exhibit higher hot TCRs, lower sheet resistivities, and lower gauge factors than those on Al2O3 substrates under typical firing conditions of 850°C for 10 minutes. As the concentration of RuO2 increases, the differences in properties between TFRs on the two substrates become less pronounced. Microstructural analyses of the interface between the resistor layer and substrate indicate that changes in properties of TFRs on FGC substrates are primarily attributed to variations in RuO2 concentration and glass phase composition, which result from interactions between the resistor layer and FGC substrate. The interaction between the FGC substrate and the resistor layer can be significantly alleviated by lowering the firing temperature from 850°C to 750°C, resulting in TFRs on FGC substrates with properties comparable to those on alumina substrates. The TFRs on FGC exhibit favorable sensitivity, linearity, repeatability, and hysteresis within the input compression strain range of 0–3043με, thus showcasing significant potential for application in structural health monitoring (SHM) in civil engineering.

Implantable Micro-optics for label-free non-linear imaging

Non-linear excitation microscopy offers superior in-vivo imaging but faces challenges in deep tissue. High numerical aperture beams suffer spherical aberrations, while tissue scattering impacts image quality. To address this, we propose implantable microlenses for precise focusing below the skin in lab animals. By using low numerical aperture lasers, we avoid spherical aberrations induced by high NA objectives. Our study presents various microlens designs differing in size, shape, and fabrication methods, all on glass or organo-hybrid ceramic substrates. This approach shows promise for enhancing deep tissue imaging, facilitating better understanding of biological processes in vivo.

Polymer coated γ-aminopropyltriethoxysilane-modified α-alumina non-spherical nanocomposite abrasives and their chemical mechanical polishing behavior on glass-ceramic substrate

Polymer coated γ-aminopropyltriethoxysilane-modified α-alumina non-spherical nanocomposite abrasives and their chemical mechanical polishing behavior on glass-ceramic substrate

LTCC glass-ceramics based on diopside/cordierite/Al2O3 for ultra-high frequency applications

In this work, three glass-ceramic composites based on a commercial SiO2-B2O3-Al2O3-CaO-MgO glass and cordierite, diopside or Al2O3 were used for preparation of green tapes and low temperature cofired ceramics (LTCC) substrates. The thermal behavior, phase composition, microstructure and dielectric properties of the fabricated glass-ceramics were characterized using a heating microscope, thermal analysis, X-ray diffraction, scanning electron microscopy and time domain spectroscopy. The applicability of the developed materials for LTCC technology was demonstrated by the preparation of test multilayer substrates. The glass-ceramic substrates exhibit advantageous properties for ultra-high frequency LTCC applications, including low sintering temperatures of 900-980°C, good compatibility with commercial Ag and AgPd conductive pastes and a low dielectric permittivity of 3.5-7 at 1 THz.

Magneto-Optical Spectroscopy of Nanocomposites (CoFeZr)x(Al2O3)100−x

We present results of magneto-optical investigations of (CoFeZr)[Formula: see text](Al2O[Formula: see text] film nanocomposites in transverse Kerr effect (TKE) geometry in the spectral range 0.5–4.0[Formula: see text]eV and magnetic field up to 3.0[Formula: see text]kOe. Nanocomposites were deposited onto a glass-ceramic substrate by ion-beam sputtering. The TKE response at room temperature strongly depends on the wavelength of light, applied magnetic field H and the volume metallic fraction. From the analysis of the field dependences of TKE at different wavelengths, it follows that in the as-deposited samples, the interaction between nanoparticles at [Formula: see text][Formula: see text]at.% is small and the nanocomposite is an ensemble of superparamagnetic particles; as x increases to 32[Formula: see text]at.%, a superspinglass-type state arises, then, in the vicinity of 34[Formula: see text]at.%, along with individual superparamagnetic particles, superferromagnetic regions appear. Long-range ferromagnetic order arises at concentrations x less than the percolation threshold for conductivity [Formula: see text][Formula: see text]at.%. In the presence of two different magnetic states in the samples, TKE is not proportional to the magnetization. Both the field dependences at near-infrared region and the spectral dependences of TKE change significantly after annealing of the samples, while the changes in the field dependences of the magnetization are almost imperceptibly.

Структурные и электрофизические свойства композитных мемристоров на основе матрицы LiNbO-=SUB=-3-=/SUB=- с разными наногранулами: Co-Fe-B и CoFe

Comparative studies of the properties of metal/nanocomposite/metal (M/NC/M) memristive structures based on NC consisting of a LiNbO 3 matrix and various Co-Fe-B or CoFe metal granules have been carried out. The M/NC/M structures were obtained using ion-beam sputtering from composite targets Co 40 Fe 40 B 20 -LiNbO 3 and Co 50 Fe 50 -LiNbO 3 on glass-ceramic substrates. The same NC layers were synthesized on polyimide substrates to study the structural features by X-ray absorption fine structure spectroscopy (XAFS). The XAFS data show an identical crystal structure of granules in both types of NC, indicating that a significant part of the B atoms during the synthesis of NC is in an insulating matrix, forming an oxide of the B 2 O 3 type, which is confirmed by X-ray photoelectron spectroscopy data. In this case, no metallic state of niobium is observed in the layers. Both types of M/NC/M structures demonstrate resistive switching (RS), however, in the case of NC with boron, the RS effect is much stronger, which is explained by the significant role of oxygen vacancies formed during the oxidation of boron in the RS.

Peculiarities of the Processing of Polycrystalline AlN Films on Glass-Ceramic and Si Substrates by Argon Cluster Ions

Peculiarities of the Processing of Polycrystalline AlN Films on Glass-Ceramic and Si Substrates by Argon Cluster Ions

The Influence of Argon Cluster Ion Bombardment on the Characteristics of AlN Films on Glass-Ceramics and Si Substrates.

In this paper, the influence of surface modification on the characteristics and properties of AlN thin films on Si and glass-ceramics substrates is investigated. The surface modification was made at various parameters of argon cluster ions. By using XRD and Raman spectroscopy, it was shown that the obtained AlN films have a hexagonal structure with a characteristic direction of texturing along the c axis and slight deviations from it. A comparison of the AlN surface morphology obtained by atomic force microscopy before and after cluster processing was demonstrated. This demonstrated that the cluster ions with low energy per atom (E/N = 10 eV/atom) have a high efficiency of surface smoothing. A decrease in the intensity of the Raman peaks and an increase in their full-width after bombardment with cluster ions were found, which may be caused by a change in the physicochemical state of the surface. The optical properties, the quality of the boundaries, and the distribution map of the thickness of the functional layer of AlN were investigated by the methods of spectral and spatial resolution ellipsometry. By using the cross-sectional SEM, the direction of crystallite texturing was demonstrated. The influence of argon cluster ion bombardment on the stoichiometry of samples was analyzed by EDX spectroscopy. The results obtained demonstrate the efficiency of the cluster ion smoothing of polycrystalline thin films for microelectronics, particularly when creating surface acoustic wave resonators.

Механические напряжения в тонких пленках цирконата-титаната свинца, сформированных на подложках, отличающихся температурными коэффициентами линейного расширения

The article considers the influence of linear and bending stresses on the magnitude of the internal field and self-polarisation in thin lead zirconate titanate (PZT) films formed on silicon and glass-ceramic ST-50 substrates by radio-frequency magnetron sputtering. PZT composition corresponded to the region of the morphotropic phase boundary. It is assumed that bending stresses in “thin PZT film-substrate” bimorph structures lead to the appearance of an internal electric field caused by the diffusion of charged oxygen vacancies (Gorsky effect in ferroelectrics).

Asymmetric magnetization reversal processes in amorphous composites (Fe40Co40B20)x(AL2O3)100-x

The amorphous composite films (Co40Fe40B20)x(Al2O3)100-x with different content of the metal (Co40Fe40B20)x “(CoFeB)x” and the dielectric (Al2O3)100-x components were obtained in the original ion-beam deposition unit. Sputtering of a composite target from an amorphous Co40Fe40B20 alloy plate with dielectric Al2O3 inserts was carried out in the argon atmosphere at an operating pressure of ∼5.10–4 Torr on glass-ceramic Sitall substrates. The presence of two regions in the IR spectra of composites with different values of х confirms the existence of the metal and dielectric components during the ion-plasma deposition of composites on a sitall substrate as a result of self-arrangement. The magnetic hysteresis was measured at room temperature for (CoFeB)x(Al2O3)100-x thin film samples for x = 1, 75 and from 9 to 69 with the step x = 10 at different angles (φ) when magnetic field applied out of a plane (φ = 90°) and in-plane (φ = 0°) of the films. The obtained results show that at low alloy (CoFeB)x contents the film composites with nominal x = 1, 9, and 19 behave as paramagnetic from the first glance. With an increase of the alloy (CoFeB)x content to nominal x = 29–75 amorphous composites films seems as superparamagnetic and ferromagnetic materials that are characterized as reversal magnetization with no coercivity and remanence. The existence of a magnetic vortex in the samples with x = 59–75 opens different remarkable applications like data storage.

Effect of Partial Ba Substitutions on the Crystallization of Sr2TiSi2O8 (STS) Glass-Ceramics and on the Generation of a SAW Signal at High Temperatures.

Because of their characteristics, including a d33 of 10–15 pC/N and high stability up to temperatures over 1000 °C, polar glass–ceramics containing fresnoite crystals can be regarded as highly effective materials for applications requiring piezoelectricity at high temperatures. In the present paper we investigate barium substitutions in an Sr-fresnoite (STS) glass–ceramic. Two aspects are studied: first, the effect of the substitution on the preferential orientation of the crystallization, and second, the ability of the glass–ceramics to generate and propagate surface acoustic waves (SAW) at high temperatures. XRD analyses show that a 10 at.% substitution of Ba allows us to keep a strong preferential orientation of the (00l) planes of the fresnoite crystals down to more than 1 mm below the surfaces. Higher substitution levels (25 and 50 at.%), induce a non-oriented volume crystallization mechanism that competes with the surface mechanism. SAW devices were fabricated from glass–ceramic substrates with 0, 10 and 25 at.% Ba substitutions. Temperature testing reveals the high stability of the frequency and delay for all of these devices. The glass–ceramic with a 10 at.% Ba substitution gives the strongest amplitude of the SAW signal. This is attributed to the high (00l) preferential orientation and the absence of disoriented volume crystallization.

Effect of Phase Transformations of a Metal Component on the Magneto-Optical Properties of Thin-Films Nanocomposites (CoFeZr)x (MgF2)100-x.

The results of complex studies of structural-phase transformations and magneto-optical properties of nanocomposites (CoFeZr)x (MgF2)100−x depending on the metal alloy content in the dielectric matrix are presented. Nanocomposites were deposited by ion-beam sputtering onto glass and glass-ceramic substrate. By studying the spectral and field dependences of the transversal Kerr effect (TKE), it was found that the transition of nanocomposites from superparamagnetic to the ferromagnetic state occurs in the region of xfm~30 at%, that corresponds to the onset the formation of ferromagnetic nanocrystals CoFeZr with hexagonal syngony in amorphous dielectric matrix of MgF2. With an increase of concentrations of the metal alloy for x > xfm, the features associated with structural transitions in magnetic granules are revealed in the TKE spectra. Comparison of the spectral and concentration dependences of TKE for nanocomposites on the glass and glass-ceramics substrates showed that the strongest differences occur in the region of the phase structural transition of CoFeZr nanocrystals from a hexagonal to a body-centered cubic structure at x = 38 at.% on the glass substrates and at x = 46 at.% on glass-ceramics substrates, due to different diffusion rates and different size of metal nanocrystals on amorphous glass substrates and more rough polycrystalline glass-ceramics substrates.

Quantitative investigation of abrasive grit size dependency of subsurface damages for the metal-bonded abrasives on Zerodur glass-ceramic

We present a quantitative evaluation of abrasive grit size dependency of subsurface damages on Zerodur glass-ceramic substrates induced by precision grinding. The depths of subsurface damages are evaluated for the metal-bonded grinding cup tools with four different grit sizes, D126, D64, D35, and D15, for the fixed nominal grinding process parameters. The micro-crack depth is driven by the mechanism between the abrasive grit and brittle glass, which generates median or radial cracks through the bulk material. The initiation and propagation of subsurface damages beneath the brittle glass-ceramic substrate of Zerodur are explored by the cross-sectional polishing method, which takes advantage of the optical contact bonding method without any adhesive, and are imaged by scanning electron microscopy. A novel hybrid methodology, which comprises both destructive and non-destructive subsurface evaluation tools, is developed and employed for evaluating the micro-cracks quantitively. The procedure is based on a repetitive and consecutive chemical acid etching after the surface is grounded, flat substrate polishing with a conventional polishing machine, a white light interferometer, and an image analysis. The four grit sizes, D126, D64, D35, and D15, correspond to the rough cut through to the complete precision grinding’s fine cut. The subsurface damages are measured to be 71 µm, 35 µm, 25 µm, and 7 µm from rough to fine grit sizes. The results are consistent with the theoretical model and previous work.

High-adhesion unlayered films: physical and technological basis of their production

Using the modernized three-electrode ion-plasma sputtering method, high-adhesion Cu-films without underlayer were obtained. Films were deposited on glass-ceramic (sitall) substrates. The film thickness was ~500 nm. In this case, the calculated cooling rate reached ~ 1012–1014 K/s. The adhesion properties of Cu films were investigated by the standard method of mechanical separation of the film from the substrate – the “fungus” method. It is established that such film adhesion is more than 20 MPa. It is determined that the obtained high adhesion depends on bias potential value. Using these Cu films in strip resonators without a sublayer makes it possible to increase their Q-factor by 1.5–1.7 times and thereby significantly reduce the resulting operating noise.

The Use of Additive Laser Technology for the Synthesis of Silicate Coatings in the Correction of the Shape of Precision Optical Surfaces

The work is devoted to the development of the technology for the formation of the required microrelief of the optical surfaces of glass-ceramic substrates. The solution of the problem using a controlled local deposition of silicon dioxide on the polished surface by laser pyrolysis of tetraethoxysilane vapor in the presence of ozone is shown. The characteristics of the experimental samples, their comparison with the data of mathematical modeling of the results of technological processes are presented. The possibility of using the developed technology for the production of substrates of optical parts with a defined wedge-shaped value is shown.