Metastable Amorphous Phase Research Articles

Nature of Thermal Hysteresis of Thermoelectric Properties in Ag2TexS1-x Compounds.

Ag2TexS1-x usually undergo various phase structures upon heating or cooling processes; however, the correlation between the heat treatment, the phase structure, and the physical properties is still a controversy. Herein, three different phases are realized for Ag2TexS1-x (0.35 ≤ x ≤ 0.65) samples during the heat treatment, including the low-temperature crystalline phase, amorphous phase, and high-temperature cubic phase. The metastable amorphous phase is an intermediate phase formed during transition from the high-temperature cubic phase to the low-temperature crystalline phase upon cooling via a solid-state conversion rather than the conventional liquid quenching process. The relative content of these three phases is highly sensitive to the heat treatment process. This as-formed low-temperature crystalline phase, amorphous phase, and high-temperature cubic phase convert into the low-temperature crystalline phase and high-temperature cubic phase through long-time dwelling at the temperature below or above the transition temperature around 567 K, respectively. The status of the low-temperature crystalline phase, amorphous phase, and high-temperature cubic phase significantly affects the thermoelectric properties, resulting in the thermal hysteresis of thermoelectric properties. Below the phase transition temperature (TM), the electrical conductivity of the amorphous phase surpasses that of the low-temperature crystalline phase, which shows a growth of 112% for the Ag2Te0.60S0.40 sample annealed at 823 K in comparison with that of the sample annealed at 473 K. For Ag2Te0.50S0.50 samples annealed at 473 K, the maximum ZT value reaches 1.02 at 623 K during the initial test, while the maximum ZT value is improved to 1.34 at 523 K in the second-round test.

Composition, time, temperature, and annealing-process dependences of crystalline and amorphous phases in ductile semiconductors Ag2S1−xTex with x = 0.3–0.6

We investigate composition, time, temperature, and annealing-process dependences of crystalline and amorphous phases in ductile semiconductors Ag2S1−xTex with x = 0.3–0.6. We reveal that a metastable amorphous phase containing no secondary phases is obtainable at x = 0.6 even with furnace cooling and possesses ductility in the same manner as the end compound of Ag2S, while the high-temperature phase (HTP) of Ag2S precipitates in the amorphous phase at x = 0.3–0.5 by keeping the good ductility. During the crystallization process of the amorphous phase by annealing a sample at 373–503 K for 4–14 days and cooling it down slowly to room temperature, HTP of Ag2S disappears and the low-temperature phase (LTP) of Ag2S and the Ag5−dTe3 phase appear, while the amorphous phase remains. The ductility is observed for the samples containing the LTP of Ag2S but not for those containing the Ag5−dTe3 phase. Based on the obtained results, the possible phase diagram of Ag2S1−xTex with x = 0.3–0.6 is proposed, and the origin of the ductility in the LTP and HTP of Ag2S and amorphous phase is discussed. We believe that our study is helpful for properly predicting mechanical and transport properties of this material and developing this material as a component of bendable/wearable electronic devices for long-term use.

Tailoring the structure and self-activated photoluminescence of carbonated amorphous calcium phosphate nanoparticles for bioimaging applications.

Self-activated luminescent calcium phosphate (CaP) nanoparticles, including hydroxyapatite (HA) and amorphous calcium phosphate (ACP), are promising for bioimaging and theragnostic applications in nanomedicine, eliminating the need for activator ions or fluorophores. In this study, we developed luminescent and stable citrate-functionalized carbonated ACP nanoparticles for bioimaging purposes. Our findings revealed that both the CO32- content and the posterior heating step at 400 °C significantly influenced the composition and the structural ordering of the chemically precipitated ACP nanoparticles, impacting the intensity, broadness, and position of the defect-related photoluminescence (PL) emission band. The heat-treated samples also exhibited excitation-dependent PL under excitation wavelengths typically used in bioimaging (λexc = 405, 488, 561, and 640 nm). Citrate functionalization improved the PL intensity of the nanoparticles by inhibiting non-radiative deactivation mechanisms in solution. Additionally, it resulted in an increased colloidal stability and reduced aggregation, high stability of the metastable amorphous phase and the PL emission for at least 96 h in water and supplemented culture medium. MTT assay of HepaRG cells, incubated for 24 and 48 h with the nanoparticles in concentrations ranging from 10 to 320 μg mL-1, evidenced their high biocompatibility. Internalization studies using the nanoparticles self-activated luminescence showed that cellular uptake of the nanoparticles is both time (4-24 h) and concentration (160-320 μg mL-1) dependent. Experiments using confocal laser scanning microscopy allowed the successful imaging of the nanoparticles inside cells via their intrinsic PL after 4 h of incubation. Our results highlight the potential use of citrate-functionalized carbonated ACP nanoparticles for use in internalization assays and bioimaging procedures.

High-Entropy Oxides in the Mullite-Type Structure.

High-entropy materials (HEMs) represent a new class of solid solutions containing at least five different elements. Their compositional diversity makes them promising as platforms for the development of functional materials. We synthesized new HEMs in a mullite-type structure and present five compounds, i.e., Bi2(Al0.25Ga0.25Fe0.25Mn0.25)4O9 and A2Mn4O10 with variations of A = Nd, Sm, Y, Er, Eu, Ce, and Bi, demonstrating the vast accessible composition space. By combining scattering, microscopy, and spectroscopy techniques, we show that our materials are mixed solid solutions. Remarkably, when following their crystallization in situ using X-ray diffraction and X-ray absorption spectroscopy, we find that the HEMs form through a metastable amorphous phase without the formation of any crystalline intermediates. We expect that our synthesis is excellently suited to synthesizing diverse HEMs and therefore will have a significant impact on their future exploration.

Structural Transformation of Unconventional-Phase Materials.

The structural transformation of materials, which involves the evolution of different structural features, including phase, composition, morphology, etc., under external conditions, represents an important fundamental phenomenon and has drawn substantial research interest. Recently, materials with unconventional phases that are different from their thermodynamically stable ones have been demonstrated to possess distinct properties and compelling functions and can further serve as starting materials for structural transformation studies. The identification and mechanism study of the structural transformation process of unconventional-phase starting materials can not only provide deep insights into their thermodynamic stability in potential applications but also offer effective approaches for the synthesis of other unconventional structures. Here, we briefly summarize the recent research progress on the structural transformation of some typical starting materials with various unconventional phases, including the metastable crystalline phase, amorphous phase, and heterophase, induced by different approaches. The importance of unconventional-phase starting materials in the structural modulation of resultant intermediates and products will be highlighted. The employment of diverse in situ/operando characterization techniques and theoretical simulations in studying the mechanism of the structural transformation process will also be introduced. Finally, we discuss the existing challenges in this emerging research field and provide some future research directions.

Explanation and prediction for the crystallized products from amorphous bicalutamide and bicalutamide solutions by using mid-frequency Raman difference spectra

Bicalutamide (BIC) is one fluorine-containing drug with poor aqueous solubility, and it is essential to study the polymorphism of BIC, especially the metastable polymorphs and amorphous phase, to improve the oral effect. Selective crystallizations of BIC amorphous phases and solutions were studied and further explained and predicted by using mid-frequency Raman difference spectra (MFRDS) here. The relationships among various polymorphs and solutions of BIC were established by calculating the values of average deviation (a. d., the average value of absolute value of the intensity of MFRDS) and standard deviation (s. d.) of the MFRDS. And the possible routes to obtain metastable Form II and amorphous BIC were proposed based on the MFRDS results. Metastable Form II can be obtained by recrystallization of the amorphous BIC prepared through melt-quenching method. Amorphous BIC without additives can be prepared through a quicky evaporation process of acetone and ethyl acetate solutions, which was reported for the first time. The MFRDS results confirmed the presence of residual acetone and ethyl acetate in amorphous BIC obtained by evaporation, and the residual solvents changed the recrystallization products of amorphous BIC. MFRDS analysis can be a useful tool to guide the preparation and selective crystallization of metastable polymorphs and amorphous phase.

Microstructure and Properties of Multilayer Niobium-Aluminum Composites Fabricated by Explosive Welding

In this study, a layered composite material consisting of alternating aluminum and niobium layers and cladded on both sides with titanium plates was obtained by explosive welding. Microstructure of the composite was thoroughly studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as by energy dispersive X-ray spectroscopy (EDX) and electron backscattered diffraction (EBSD). Microhardness measurements, tensile test, and impact strength test were carried out to evaluate the mechanical properties of the composite. Formation of mixing zones observed near all interfaces was explained by local melting and subsequent rapid solidification. Mixing zones at Nb/Al interfaces consisted of metastable amorphous and ultrafine crystalline phases, as well as NbAl3 and Nb2Al equilibrium phases. Niobium grains near the interface were significantly elongated, while aluminum grains were almost equiaxed. Crystalline grains inside the mixing zones did not have a distinct crystallographic texture. Microhardness of Al/Nb mixing zones was in the range 546–668 HV, which significantly exceeds the microhardness of initial materials. Tensile strength and impact strength of the composite were 535 MPa and 82 J/cm2, respectively. These results confirm the high bonding strength between the layers.

Plastic TiZrHfCoNiCu high entropy alloy via stable B2 phase

(Ti, Zr, Hf)(Co, Ni, Cu) high entropy alloys (HEAs) have excellent properties such as high-temperature shape memory property and high yield strength that have attracted widespread attention in recent years, but their application has been limited due to the lack of plastic deformability. In this work, we examined the possibility of synthesizing a new HEA with good mechanical properties by controlling the formation ability of metastable amorphous (am) and B2 phases for Ti16.5Zr17Hf16.5Co16.5Ni16.5Cu17 HEA. The as-spun amorphous and [am＋B2] phase ribbons with good bending plasticity were formed. The mixed-phase ribbon exhibits higher tensile plasticity than the amorphous ribbon because of the easy generation of shear bands and the suppression of their propagation around the B2 phase. Besides, the B2 phase is formed for the cast rod with a diameter of 2 mm. The B2 rod exhibits compressive strength up to 2254 MPa and a plastic strain of about 5%. The B2 alloy rod also has high thermal stability and keeps good mechanical properties after annealing under 973 K for 1.8 ks. The high mechanical strength and good plasticity of the B2 HEA are due to the generations of deformation-induced dislocation and martensite B33 phase. The synthesis of the B2 HEA with excellent mechanical properties through the deformation-induced martensite transformation is promising for future structural material.

Chemical Stability of Atomic Layer Deposited (ALD) Alumina Thin Films in Aqueous Solutions

Aluminum oxide (alumina) thin films deposited through atomic layer deposition (ALD) are of great interest in chemical barrier and corrosion protection applications. However, the stability of ALD alumina in aqueous solutions is still not fully understood. Due to its metastable amorphous phase, the hydration and degradation behavior of ALD alumina films behaves differently from its crystalline Al2O3 counterpart. A full understanding of why these films hydrate and/or dissolve requires the exploration of different deposition conditions and ion content in solutions used. This talk will discuss efforts to further elucidate the hydration and dissolution behavior of ALD alumina films. For this study, alumina thin films were ALD deposited onto silicon substrate at 150 °C using trimethylaluminum (TMA) and H2O. These films were then studied in Type 1 DI water, 2M NaCl, .5M NaCl, and .1M NaCl solutions at room temperature. Films were gently dried using a nitrogen gun and thickness was measured using a Cauchy ellipsometry model. After 15 days of immersion in Type 1 DI water, significant thickness growth is observed at twice (27 days) and 2.5 times (33 days) the normalized thickness. Similar hydration is not observed in salt-containing aqueous solutions nor upon exposure to air. We will discuss the possible effects of CO2 dissolution and carbonate formation as well as ionic species on the hydration and dissolution processes of these alumina films. Finally, we will show how a post-ALD plasma treatment to the film’s surface alters the hydration and dissolution behavior, improving stability in several aqueous conditions.

High-Speed Growth of Epitaxial Rutile GeO2 Thin Film on (001) TiO2 Under Highly Oxygen-Rich Condition and Its Structural Analysis

Recently, rutile germanium dioxide (r-GeO2) has been proposed as a novel ultra-wide bandgap (UWBG) semiconductor with ambipolar dopability, high carrier mobilities, and a higher thermal conductivity than Ga2O3, in addition to its wide bandgap (4.68 eV). These excellent properties indicate that r-GeO2 can be utilized as high-performance bipolar devices with high breakdown voltage. On the other hand, although r-GeO2 is most stable phase at the ambient condition, fabrication of its thin film is reported to be quite difficult, owing to the existence of energetically deep meta-stable phases, namely, amorphous and quartz phase, and high vapor pressure of r-GeO2. In this study, we accomplished fabrication of (001)-oriented r-GeO2 thin films on (001) rutile titanium dioxide (r-TiO2) substrate with high growth rate (≧1 mm/h) by mist chemical vapor deposition (mist CVD). Moreover, we investigated the structural properties of r-GeO2 film by X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques.First of all, bis [2-carboxyethylgermanium (IV)] sesquioxide (C6H10Ge2O7) as a precursor. To analyze the decomposition process of C6H10Ge2O7 and optimize the growth conditions, Thermogravimetry-Differential Thermal Analysis (TG-DTA) was conducted in aqueous vapor. By the TG-DTA, GeO2 was found to be synthesized from C6H10Ge2O7 at 553-783 ℃ in aqueous vapor. Therefore, we determined the growth temperature of r-GeO2 thin film to be 550-850 ℃. As shown in XRD 2q/w scan profile (Fig. 1), (001)-oriented r-GeO2 thin film was grown on (001) r-TiO2 substrate at growth temperature (T g) of 700-775 ℃. The growth rates of all the r-GeO2 films were found to be 1.2-1.7 mm/h, which were much higher than those grown by molecular beam epitaxy (MBE) (10 nm/h). Moreover, XRD F scan revealed that r-GeO2 thin film was epitaxially grown without rotational domains.It is considered that the higher growth rate by mist CVD compared to that by MBE is attributed to the lower desorption rate of GeO in mist CVD due to its highly oxygen-rich condition. In Fig. 2, we show the schematics of GeO desorption from the surface in (a) MBE and (b) mist CVD, inspired by Wang et al. In mist CVD, oxygen partial pressure is much higher (~760 Torr) than that in MBE (1×10- 6 Torr), resulting lower vapor pressure of GeO and lower desorption rate in mist CVD system. Higher oxygen partial pressure also suppresses oxygen vacancies in the film. Moreover, in mist CVD, oxygen was continuously supplied by water in the reaction area. Therefore, such highly oxygen-rich condition as seen in mist CVD is considered to contribute to high temperature growth and high growth rate.Cross-sectional TEM image and Selected Area Electron Diffraction (SAED) patterns at r-TiO2 substrate and the r-GeO2/r-TiO2 interface viewed along the <110> zone axis are shown in Fig. 3 (a), (b), and (c), respectively. The r-GeO2 thin film for the TEM observation was grown at lower growth rate (50 nm/h) for higher crystallinity. In Fig. 3 (b), clear diffraction spots of r-TiO2 substrate were visible. On the other hand, in Fig. 3 (c), clear diffraction spots of r-GeO2 thin film were observed as well as those of r-TiO2 substrate at the interface. From the diffraction spots, we calculated lattice parameters of the r-GeO2 thin film to be a=4.5 Å and c=2.7 Å. This indicates that the film suffers from significant tensile stress along the in-plane direction, and in-plane strain value was ~2.3%. Thus, in order to release the strain and achieve higher crystalline quality, using a buffer layer or other substrates with less lattice mismatches to r-GeO2 may be needed.We believe that these results greatly contribute to the future development of r-GeO2 applied for power-electronics devices and exploration of novel materials that are difficult to synthesize under normal growth conditions.This work was supported, in part, by JSPS KAKENHI under Grant No. 21H01811. Figure 1

Thermodynamic and kinetic features of the formation of amorphous state in films during quenching from the vapor state

The method of modernized ion-plasma sputtering produced metastable states, including nanocrystalline and amorphous phases in films, even in alloys whose components do not mixed in the liquid state. The effective rate of energy relaxation at different modes of precipitation is theoretically estimated to be 1012 -1014 K/s during ion-plasma sputtering of atoms. On thermodynamic and kinetic states, different active and passive parameters for amorphization during sputtering are analyzed. The receiving expressions are in good agreement with the experimental results and contribute to the determination of further steps to obtain an amorphous state.

Amorphous Sn–Ni islets with high structural integrity as an anode material for lithium-ion storage

To the best of our knowledge, the study described herein is the first to demonstrate the use of amorphous Sn–Ni islets as an anode material for lithium-ion storage. The islets are prepared by co-electrodeposition (2 s). In general, amorphous Sn–metal alloys exhibit significantly improved cycling performances over those of crystalline alloys with similar compositions and morphologies. However, to date, no thermodynamically metastable amorphous phase has been found in Sn–Ni alloys of any composition. Here, we show that the amorphization of such alloys is possible by ensuring rapid co-electrodeposition, so as to prevent Sn and Ni from crystallizing. The resulting amorphous Sn–Ni alloy affords suppressed capacity degradation due to the preservation of its initial microislet-shaped particles and its structural integrity after cycling. This is primarily due to the volume changes in the amorphous phase being small. These findings indicate the potential of this newly developed amorphous Sn–Ni alloy to be used as an anode material for lithium-ion rechargeable batteries.

Structure and еlectrocatalytic ability of Sn–Ni alloy powders prepared by direct and pulse electrodeposition

Sn–Ni alloy powders with a wide range of compositions and structures by constant current, constant potential and pulse potential modes were deposited. Increasing the Ni2+/Sn2+ ratio in the electrolyte from 1 to 8 in both stationary modes leads to changes in the shape and composition of the powder particles from typically dendritic (5 ÷ 7 wt%Ni), to cauliflower-like (90 ÷ 98 wt%Ni). With only an increasе of the pulse frequency from 100 to 1000 Hz, almost 20% increase in the nickel content is achieved. The Sn–Ni powders deposited in both potentiostatic modes have much more homogeneous structure than those, deposited by galvanostatic mode. The powders are composed mainly from a cubic phase (f.c.c.) of β-Ni and of small amounts of β-Sn as a result of recrystallization from metastable amorphous tin phase. The Sn–Ni powders show electrocatalytic alility to the oxygen reduction reaction (ORR) in a model Metal-Air system seriously excel features of the reference (Ag) catalyst. The ORR is very sensitive to the morphology of the tested electrocatalysts.

Self-Assembly of Patchy Colloidal Rods into Photonic Crystals Robust to Stacking Faults.

Diamond-structured colloidal photonic crystals are much sought-after for their applications in visible light management because of their ability to support a complete photonic band gap (PBG). However, their realization via self-assembly pathways is a long-standing challenge. This challenge is rooted in three fundamental problems: the design of building blocks that assemble into diamond-like structures, the sensitivity of the PBG to stacking faults, and ensuring that the PBG opens at an experimentally attainable refractive index. Here we address these problems simultaneously using a multipronged computational approach. We use reverse engineering to establish the design principles for the rod-connected diamond structure (RCD), the so-called "champion" photonic crystal. We devise two distinct self-assembly routes for designer triblock patchy colloidal rods, both proceeding via tetrahedral clusters to yield a mixed phase of cubic and hexagonal polymorphs closely related to RCD. We use Monte Carlo simulations to show how these routes avoid a metastable amorphous phase. Finally, we show that both the polymorphs support spectrally overlapping PBGs. Importantly, randomly stacked hybrids of these polymorphs also display PBGs, thus circumventing the requirement of polymorph selection in a scalable fabrication method.

Anomalous conductivity behavior induced by in situ metastable amorphous phase in BaTiO3/Ni0.5Zn0.5Fe2O4 ceramic composite

The electrical conductivity of ferroelectric-ferromagnetic ceramic composites usually increases monotonously with elevated temperature, which may seriously deteriorate their performance. In this work, we report an anomalous conductivity behavior induced by in situ metastable amorphous phase in a semi-conductive ceramic composite, 0.1BaTiO3(BTO)/0.9Ni0.5Zn0.5Fe2O4(NZFO). The ceramic composites with in situ formed amorphous BTO phase (a-BTO) or crystalline BTO phase (c-BTO) were successfully prepared. The effect of such metastable amorphous phase on the electrical transport properties of the ceramic composite was investigated. A comparative study reveals that a-BTO could act as a buffering phase preventing the electrical conductivity of the composite from monotonous increment above a critical temperature (513 K), whereas such effect does not occur when BTO is pure crystalline. Around 513 K, a change in the activation energy of dc conductivity has been observed for the c-BTO/NZFO sample. Whereas for the a-BTO/NZFO sample, the Arrhenius relation fails to describe its behavior above 513 K owing to decreased conductivity, which is rarely seen in semiconductors. The activation energy of relaxation is identical for both systems, i.e. 0.204 eV, because their dielectric relaxation is dominated by crystalline NZFO phase. The findings of this work are inspiring for the design of novel electronic materials constituted by a crystalline phase and an amorphous phase with adjustable performance.

Investigation of the reduction roasting of saprolite ores in the Caron Process: microstructure and thermodynamic analysis

ABSTRACT Studies have been undertaken to investigate the thermodynamic aspects of the reduction roasting of saprolite ores in the Caron Process. Reduction experiments have been conducted in controlled oxygen partial pressure conditions at selected temperatures. Detailed microstructure characterisation and thermodynamic analysis of reduced ore samples, focusing on the phase transformations, nickel recoveries and Ni-Fe alloy compositions produced, were carried out. Comparison has been made between the experimental results and FactSage thermodynamic predictions for these conditions. The differences between between the experimental and predicted results are discussed. It has been shown that the system below 700°C is approximated thermodynamically by considering the nickel–iron alloy product to be in chemical equilibrium with a metastable amorphous oxide phase.

Influencing factors on the amorphous phase formation in Fe–7.7 at% Sm alloys solidified by high-speed melt spinning

The metastable SmFe12 stoichiometric compound has been reported to have superior magnetic properties to the traditional Nd2Fe14B intermetallic compound that can be massively produced by the widely used melt-spinning technique. However, there have been no reports on the successful synthesis of the bulk metastable SmFe12 or amorphous phase with the composition of Fe–7.7 at% Sm (the SmFe12 phase composition) via the aforementioned technique. In the present study, the binary Fe–7.7 at% Sm melt was spun onto a high-speed single Cu roller under various processing conditions. The influencing factors, e.g., the diameter of the nozzle orifice, the ejection gas pressure, and the species of the chamber gas, were examined to clarify the production condition of the amorphous ribbon. It has been confirmed that the careful control of the processing conditions enables the binary Fe–7.7 at% Sm melt to be spun into amorphous ribbons. Based on the in-situ observation of a high-speed video (HSV) camera, a simple model that illustrates the separation of the ribbon from the melt reservoir was proposed, from which the cooling curves of ribbons with different thickness were calculated. Further analysis indicated that both the model and the numerical calculation results agree well with the high resolution TEM observations near the free surface and the roller sides in terms of the structure formation.

Capturing an amorphous BaSO4 intermediate precursor to barite

In the work presented here, free-barium activity was monitored during the barium sulfate crystallization and we identified for the first time (in the absence of additives) a metastable BaSO4 amorphous phase that precedes barite formation.

A study of the hydrogen bonds effect on the water density and the liquid-liquid transition

We study the hydrogen bonds effect on the water density as a function of temperature and pressure from the supercritical region to the metastable supercooled and amorphous phases. We identify two important thermodynamic thresholds, that is $P^{\ast~}\simeq2~{~\rm~kbar}$ and $T^{\ast~}\simeq~315~{~\rm~K}$, that separate two different water behaviors in terms of hydrogen bonding capability. For $T<T^{\ast~}$ and $P<P^{\ast~}$ the formation and stability of hydrogen bonded local structures are enhanced. The additional analyses of the proton NMR chemical shift and of the relaxation time confirm this evidence and highlight the structure breaking effects of the pressure. The investigation of both structural and dynamical quantities allow us to draw a complete picture of the water properties in terms of the temperature-pressure dependence of hydrogen bonding.

Physical properties and structure of vapor-quenched immiscible alloys

The method of modernized ion-plasma sputtering produced metastable states, including nanocrystalline and amorphous phases in films of Fe-Ag, Fe-Bi, Fe-Ag-Bi, Fe-Co-Ag and Ni-Ag alloys whose components do not mixed in the liquid state. The periods of the crystal lattices and the dimensions of the crystallites of the nonequilibrium phases in the fresh-sputtered state and after the heating are determined. The temperatures of the beginning and the end of the decomposition of metastable phases are established when heated at a constant rate. The electric and hysteretic magnetic properties of films in freshly dusted and thermally processed states are measured. The compositions and conditions for obtaining films with low values of the temperature coefficient of electrical resistivity (~ 10-5 K-1) and high coercive force (HC ~ 150 kA/m) are established. Such films can be promising for use as thin-film precision resistors and magnetic information carriers with an increased recording density.