Oxide Grains Research Articles

Study of the influence of the ZnO:Al polycrystalline film morphology on the silver nanoparticles formation

The paper presents the results of the optical and structural properties studies of samples consisting of ZnO:Al (AZO) oxide films with an intermediate silver nanoparticles layer. Obtaining samples were carried out by the method of sol-gel technology using different types of composition, and the conditions for drying and final annealing of the samples were varied. The study of the samples optical properties consisted of the optical absorption spectra measurements, and their structural properties were determined by X-ray diffraction and small-angle X-ray scattering. Comparison of data obtained from measurements of optical and structural properties of samples confirmed the results obtained from modeling in the Comsol Multiphysics software. X-ray diffraction demonstrated that the AZO films have a polycrystalline structure and are highly textured in the [002] direction. Zinc oxide grains are 10-15 nm. Silver nanoparticles are the comparable with AZO grains and have dimensions of several tens of nanometers. An increase in the annealing temperature of the films leads to a redistribution of silver nanoparticles in the AZO film, the distance between the particles increases. Consequently, the effect of the plasmon eigenmodes of the nanoparticles prevails over the effect of the system of particles oscillations interacting with each other. The analysis of the coatings obtained by the method of small-angle X-ray scattering showed that nanoparticles in the AZO film form an ordered structure.

The effect of grain boundary structure on the intergranular degradation behavior of solution annealed alloy 690 in high temperature, hydrogenated water

The environmental degradation of four different types of grain boundaries were investigated on alloy 690 following slow strain rate tensile tests in 360°C hydrogenated water. Random high angle boundaries (RHABs) support fast Cr diffusion that promotes the formation of a continuous surface oxide film and grain boundary migration. Surprisingly, coherent twin boundaries (CTBs) are susceptible to intergranular oxidation and do not exhibit Cr diffusion or grain boundary migration. When CTBs are changed to transformed twin boundaries (TTBs) by cold work, they behave like RHABs. Finally, incoherent twin boundaries (ITBs) undergo intergranular oxidation with limited Cr depletion but no boundary migration beyond the oxide. The Cr diffusivity along grain boundary in this alloy is directly related to the density of coincident site in the grain boundary plane and determines the morphology of oxide formed near the grain boundary. CTBs are still highly resistant to stress corrosion cracking (SCC) due to the semi-coherent interface between the intergranular chromia and grain matrix. In contrast, the intergranular oxides formed along RHABs inherit highly-disordered boundary structure from the original grain boundaries and show much higher SCC susceptibility. The grain boundary structure dependence of SCC resistance should be understood from its effects on solute diffusivity, structure of intergranular oxide and the local stress-strain state.

Transport properties for Bi2Se3/La0.7Sr0.3MnO3 composites

Topological insulator/perovskite manganese oxide composites (Bi2Se3/La0.7Sr0.3MnO3) were prepared using the bonded-exfoliated method and the transport properties were studied. The resistivity of the bonded manganese oxide substrate was 6 orders of magnitude larger than that of a Bi2Se3 single crystal, implying that the bonded manganese oxide acted as an insulator substrate. The intrinsic resistance peak of the manganese oxide was present in the temperature-dependent resistivity curve. Metal-insulator transition induced by the magnetic field at a low temperature was observed. The simple parallel model cannot account for the electrical properties, as the conducting manganese oxide grains were bonded by polymeric silicone rubber and resistivity peaks were present only when the thickness of the Bi2Se3 layer was less than 1.043 μm. The spin injection may be present in the composite structure.

A multimaterial based on metallic copper and spinel oxide made by powder bed laser fusion: A new nanostructured material for inert anode dedicated to aluminum electrolysis

Coherent 3D parts of cermets, made of spinel ferrite and metallic copper, are prepared in a nitrogen atmosphere by powder bed additive manufacturing of a mixture of oxide and metallic powders. The cermets obtained are constituted by the association of blocks of about 500 μm, which create between them, a relatively large porosity (# 35%). Each block is subdivided into intimately nested zones that are either predominantly metallic or predominantly oxide type. In the metal parts, a dispersion of oxide crystals is observed, whose size varies from ten nanometers to a few micrometers. A similar distribution of metal particles in the oxide zones is also demonstrated. The chemical compositions of metallic and oxide phases are slightly different from those in the initial powders. Due to the high energy density of the laser, the melting temperature of the metal and oxides could be reached and therefore this could explain the chemical composition variations in the phases and the shape of oxide and metallic nanometric grains. The process used can therefore be described as powder bed fusion. These nanostructured cermets have been used as inert anodes for the electrolysis of aluminum in molten cryolite. Although penalized by a high porosity, 5 mm in diameter anodes allowed to carry out an electrolysis for 4 h. Since Spark Plasma Sintering can greatly reduce their porosity, while retaining their specific microstructure, the implementation of additive manufacturing for producing inert anodes is therefore of real interest.

Preparation of nanostructured CeO2-ZrO2-based materials with stabilized surface area and their catalysis in soot oxidation

By using different precipitants to control the crystallization rate, a set of nanostructured CeO2-ZrO2-based materials with varying crystallite size, textural properties and thermal stability were synthesized, and were employed in soot catalytic oxidation. We investigated the physic-chemical properties of the materials using complementary techniques, including DSC-TGA, TEM, N2 adsorption-desorption, XRD, XPS and Hydrogen-Temperature Programmed Reduction (H2-TPR). The results indicated that the decompositions of hydroxides (M(OH)x) and carbonates (M(CO3)y) generated small and large oxide grains, respectively. Thus, the thermal stability was enhanced with increasing (NH4)2CO3 concentration, considering that the specific surface area and pore volume increased from 33 (CZ-Na) to 52 m2·g−1 (CZ-C5a) and from 0.15 to 0.34 ml·g−1, respectively, after aging at 1000 °C for 4 h. Although CZ-Na exhibited the preferable lattice oxygen mobility, it showed the worst soot oxidation activity, resulting from its sharp declined surface area and a lack of surface available oxygen. In contrast, CZ-5a with the largest amount of total surface available oxygen showed the optimal catalytic performance. Moreover, nearly no deterioration of activity was detected in CZ-5a after a long-term stability test. Therefore, soot oxidation is a surface-dependent reaction, and CeO2-ZrO2 catalyst design for this purpose should allow for stabilized high surface area.

Presolar grains in primitive ungrouped carbonaceous chondrite Northwest Africa 5958

AbstractWe report a correlated NanoSIMS‐transmission electron microscopy study of the ungrouped carbonaceous chondrite Northwest Africa (NWA) 5958. We identified 10 presolar SiC grains, 2 likely presolar graphite grains, and 20 presolar silicate and/or oxide grains in NWA 5958. We suggest a slight modification of the commonly used classification system for presolar oxides and silicates that better reflects the grains’ likely stellar origins. The matrix‐normalized presolar SiC abundance in NWA 5958 is ppm (2σ) similar to that seen in many classes of unmetamorphosed chondrites. In contrast, the matrix‐normalized abundance of presolar O‐rich phases (silicates and oxides) is ppm (2σ), much lower than seen in interplanetary dust particles and the least‐altered CR, CO, and ungrouped C chondrites, but close to that reported for CM chondrites. NanoSIMS mapping also revealed an unusual 13C‐enriched (δ13C≈100–200‰) carbonaceous rim surrounding a 1.4 μm diameter phyllosilicate grain. Transmission electron microscopy (TEM) analysis of two presolar grains with a likely origin in asymptotic giant branch stars identified one as enstatite and one as Al‐Mg spinel with minor Cr. The enstatite grain amorphized rapidly under the electron beam, suggesting partial hydration. TEM data of NWA 5958 matrix confirm that it has experienced aqueous alteration and support the suggestion of Jacquet et al. (34) that this meteorite has affinities to CM2 chondrites.

Corrosion behaviors of Zr-Sn-Nb-Fe-Mo alloys in pure water at 360 °C/18.6 MPa: Influence of annealing temperature on the anti-corrosion properties

Zr-Sn-Nb-Fe-Mo alloys are heat treated at two different temperatures (480 and 550 °C). A better corrosion resistance is obtained when annealed at 550 °C. The lower oxidation rate is attributed to the reduction of oxide grain boundary area, as the grain boundaries are the most common short-circuiting paths for oxygen diffusion. Two mechanisms are responsible for crack formation in the oxide: phase transition from tetragonal to monoclinic and delayed oxidation of precipitates. The cracks are generated continuously and linked together to form long cracks, leading to the delamination of oxide films and stress relaxation in the oxide.

Implications of Reactions Between SO2 and Basaltic Glasses for the Mineralogy of Planetary Crusts

AbstractBasalts are ubiquitous in volcanic systems on several planetary bodies, including the Earth, Mars, Venus, and Jupiter's moon Io, and are commonly associated with sulfur dioxide (SO2) degassing. We present the results of an experimental study of reactions between SO2 and basaltic glasses. We examined Fe‐free basalt, and Fe‐bearing tholeiitic and alkali basalts with a range of Fe3+/Fetotal (0.05 to 0.79) that encompass the oxygen fugacities proposed for most terrestrial planetary bodies. Tholeiitic and alkali basalts were exposed to SO2 at 600, 700, and 800 °C for 1 hr and 24 hr. Surface coatings formed on the reacted basalts; these contain CaSO4, MgSO4, Na2SO4, Na2Ca(SO4)2, Fe2O3, Fe3O4, Fe‐Ti‐(Al)‐oxides, and TiO2. Additionally, the SO2‐basalt reaction drives nucleation of crystalline phases in the substrate to form pyroxenes and possible Fe‐oxides. A silica‐rich layer forms between the substrate and sulfate coatings. More oxidized basalts may readily react with SO2 to form coatings dominated by large Ca‐sulfate and oxide grains. On less oxidized basalts (NNO−1.5 to NNO−5), reactions with SO2 will form thin, fine‐grained aggregates of sulfates; such materials are less readily detected by spectroscopy and spectrometry techniques. In contrast, in very reduced basalts (lower than NNO−5), typical of the Moon and Mercury, SO2 is typically a negligible component in the magmatic gas, and sulfides are more likely.

Comments on the article “Calculation of the electric potential and surface oxygen ion density for planar and spherical metal oxide grains by numerical solution of the Poisson equation coupled with Boltzmann and Fermi-Dirac statistics” (Sensors and Actuators B: Chemical, 293 (2019) 31–40)

The article by Barami, and Ghafarinia (Sensors and Actuators B: Chemical, 293 (2019) 31–40) considers the electric potential and surface oxygen ion density in metal oxide grains. However the problem was solved using the wrong assumptions. Specifically, the density of ionized (positively charged) donors along the nanoparticle radius was assumed to be constant, equal to the density in the massive semiconductor, and the concentration of negatively charged oxygen ions on the surface of the nanoparticle was chosen arbitrarily. The implication of the assumptions are discussed and suggestions are made for the correct approach.

Use of Acoustic Emissions to detect change in contact mechanisms caused by tool wear in abrasive belt grinding process

Abrasive belt tools are widely used for finishing processes, where the abrasive grains on the belt tool serve as the cutting edge to remove materials. The interaction between abrasive grain and the material surface might result in three contact mechanisms, i.e. rubbing, ploughing and cutting, where their nature are not fully understood. On the other hand, the performance of a coated abrasive belt tool is highly affected by the grain wear. A single grain scratch test with different abrasive grain wear conditions is conducted to explore the three contact mechanisms. Through scratch experiments of prismatic Aluminium Oxide (A12O3) grain on Aluminium 6061 workpiece, Acoustic Emission (AE) frequency signatures that correspond to the three mechanisms are examined. Dominant frequencies and energy signatures occupied by the three contact mechanisms are analysed using Short-Time Fourier Transform (STFT). The energy content of the dominant frequency signatures revealed that the cutting mechanism is more predominant on belt tool with new grains, which gradually becomes less significant as the grain wears. A similar trend is also observed in ploughing and rubbing modes with respect to the wear flat level of the belt tool. The general conclusion suggests that the intensity of contact mechanisms changes according to the condition of the abrasive grain, i.e. tool wear, and can be correlated with AE sensor data.

Microscale fracture of chromia scales

Native protective oxide scales offer resistance against corrosion for high temperature materials, which often work in extreme conditions of varying mechanical and thermal loads. The integrity of such layers is of critical importance, since their damage can lead to significant reduction in material life. Mechanical data such as fracture strain and elastic modulus are required to include oxides in material life estimation models for high temperature materials, but there is lack of such data. Their thickness is in the μm range, which makes mechanical testing for property determination difficult. Here we present a micro-mechanical testing method, based on bending of micro-cantilevers produced by focused ion beam milling, capable of circumventing the limitations of conventional approaches. We apply this method to chromia thermally grown on pure chromium, and measure fracture strains at room and high temperatures (600 °C). The measured fracture strains were found to be higher at room temperature, due to a larger fraction of transgranular fracture. Surprisingly, a large fraction of transgranular fracture was seen even in the presence of stress concentrations at grain boundaries. Removal of the stress concentrations accentuated the propensity for transgranular cracking at room temperature. Realistic values of room temperature elastic modulus were obtained as well. The observed mixed trans- and intergranular cracking points towards the need for dedicated investigations of both oxide grain boundary strength and cleavage resistance of single crystals in order to fully understand the failure mechanisms in thermally grown oxide scales.

Microbeam synchrotron radiation diffraction and fluorescence of oxide layers formed on zirconium alloys at different corrosion temperatures

Autoclave corrosion tests of Zircaloy-4 were performed at temperatures ranging from 274°C to 427 °C to determine how the characteristics of the oxide layer changed with corrosion temperature. Corroded samples were prepared in cross-section and examined at the Advanced Photon Source using x-ray diffraction and fluorescence with sub-micron spatial resolution. These measurements provide high fidelity data for characterization of the oxide layer grown on zirconium alloys over a range of temperatures to better understand the fundamental mechanisms of corrosion. It was found that the size of the monoclinic oxide grains increases with distance from the metal-oxide interface, while the average grain size of the tetragonal oxide phase decreases. This is consistent with the continuous nucleation of a mixture of equiaxed tetragonal and monoclinic grains at the metal-oxide interface, of which only the monoclinic oxide grains that are properly aligned to minimize stresses grow into long columnar oxide grains. The tetragonal phase oxide grains transform to monoclinic oxide once a critical size is reached. While the monoclinic oxide grain size increases with corrosion temperature, the tetragonal phase grain size remains below a maximum value. Evolution of the tetragonal fraction, calculated with the Garvie-Nicholson formula, was observed, with local maxima seen just before transition and local minima seen at oxide locations corresponding to the oxide kinetic transition. No difference was observed in the tetragonal phase fraction in the oxide layers formed at different corrosion temperatures. Detailed fluorescence and diffraction mapping of one sample showed the evolution of the diffraction intensity over a short range in the oxide. This work provides a systematic study revealing fundamental characteristics of the microstructure of Zircaloy-4 oxide layers to further understanding of corrosion resistance of these materials.

Oxidation kinetics of nanocrystalline Al thin films

Purpose This paper aims to study the oxidation kinetics of the nanocrystalline Al ultrathin films. The influence of structure and composition evolution during thermal oxidation will be observed. The reason for the change in the oxidation activation energy on increasing the oxidation temperature will be discussed. Design/methodology/approach Al thin films are deposited on the silicon wafers as substrates by vacuumed thermal evaporation under the base pressure of 2 × 10−4 Pa, where the substrates are not heated. A crystalline quartz sensor is used to monitor the film thickness. The film thickness varies in the range from 30 to 100 nm. To keep the silicon substrate from oxidation during thermal oxidation of the Al film, a 50-nm gold film was deposited on the back side of silicon substrate. Isothermal oxidation studies of the Al film were carried out in air to assess the oxidation kinetics at 400-600°C. Findings The activation energy is positive and low for the low temperature oxidation, but it becomes apparently negative at higher temperatures. The oxide grains are nano-sized, and γ-Al2O3 crystals are formed at above 500°C. In light of the model by Davies, the grain boundary diffusion is believed to be the reason for the logarithmic oxidation rate rule. The negative activation energy at higher temperatures is apparent, which comes from the decline of diffusion paths due to the formation of the γ-Al2O3 crystals. Originality/value It is found that the oxidation kinetics of nanocrystalline Al thin films in air at 400-600°C follows the logarithmic law, and this logarithmic oxidation rate law is related to the grain boundary diffusion. The negative activation energies in the higher temperature range can be attributed to the formation of γ-Al2O3 crystal.

CHARACTERIZATION OF IRON ORE AND SCALE FOR SYNTHESIZING VINYL PAINT

Two materials are studied to synthesize a vinyl painting. Iron ore is an iron pigment with an oolithic structure containing phosphorus. The second material is a steel by-product. The raw materials proprieties were studied by chemical, particle size, thermal, XRD and spectrophotometric analysis. The iron contents of the pigment and scale are respectively 53.18% and 73.83%. The grindability of scale is better than that of the pigment. The particle volume distribution is 0.7 to 32 µm for scale and 0.6 to 40 µm for pigment. TGA and DTA tests show that the pigment loses weight with phase dissolution by consuming energy and the scale gains weight with the formation of a new phase when the temperature increases. The SEM of the scale showed a homogeneous structure of iron oxide grains ranging from 1 to 10 μm. XRD analysis shows that the iron in the pigment is in the form of (Fe2O3) and FeO (OH)) and very little (Fe2SiO4). The iron in the scale is in the form of (FeO, Fe2O3 and Fe3O4). Spectrophotometric tests show that the two materials have no absorption and their reflection is maximum (100%) in the visible range.

High-resolution Fe–Ti oxide thermometry applied to single-clast pumices from the Bishop Tuff: a re-examination of compositional variations in phenocryst phases with temperature

Numerous analyses of multiple ilmenite, titanomagnetite, sanidine, plagioclase, biotite, orthopyroxene, and clinopyroxene crystals (when present) in each of 24 single-clast pumices from the Bishop Tuff (BT), CA are presented, together with whole-rock compositions on the same single clasts. Data from multiple Fe–Ti oxide grains in each sample, coupled with an assessment of analytical uncertainty, show that there is a single population of ilmenite and titanomagnetite in each of 20 samples and no more than two populations of ilmenite and/or titanomagnetite in the remaining four. A statistical evaluation of microprobe uncertainty (for beam conditions of 15 kV and 10 nA) constrains the minimum number of ilmenite (≥ 21) and titanomagnetite (≥ 56) analyses required to obtain Fe–Ti two-oxide temperatures with propagated uncertainties ≤ ± 10 °C. Thermometry results confirm a continuous range (~ 700–800 °C) across the BT deposit. Plagioclase displays a bimodal compositional pattern, where a predominantly sodic (An14–15) vs. calcic (An22–23) population is found in single clasts where pyroxene is absent vs. present; the latter coincides with geochemical evidence for mixing between high-SiO2 rhyolite and less differentiated melts as previously documented in the literature. When sanidine rims are paired with plagioclase, calculated two-feldspar temperatures (~ 690–780 °C) are strongly correlated (R2 = 0.94) with Fe–Ti two-oxide temperatures. Application of plagioclase–liquid hygrometry reveals a systematic decrease in melt water content (~ 7.2–4.1 wt%) with increasing temperature across the BT deposit, consistent with experiments from the literature that show cotectic crystallization of quartz–sanidine–plagioclase in rhyolite melt requires a concomitant decrease of ~ 3 wt% H2O between 700 and 800 °C at 200 MPa. Single-clast, whole-rock concentrations of some elements (e.g., Rb) correlate strongly with Fe–Ti oxide temperature (R2 = 0.95). The Mg# in biotite also correlates strongly with temperature (R2 = 0.97), as do the Mg# values in orthopyroxene and clinopyroxene with whole-rock Mg# (R2 = 0.6 and 0.8, respectively) and melt water content (R2 = 0.7 for both). Evidence points to biotite crystallization in all BT samples from high-SiO2 rhyolite melt, which was already continuously zoned in composition and temperature prior to mixing with less differentiated melts, as previously noted in the literature. In contrast, several lines of evidence, including hydrous phase-equilibrium experiments on rhyolites from the literature, show that both pyroxenes in BT pumices co-crystallized with calcic plagioclase (~ An21–29), in equilibrium with both titanomagnetite and ilmenite, after mixing between less differentiated melt(s) and relatively hot (≥ 755 °C) high-SiO2 rhyolite.

High‐Temperature Observation of Transdomain Transitions in Vortex States in Intermediate Titanomagnetite

AbstractNatural materials contain small grains of magnetic iron oxides that can record information about the magnetic field of the Earth when they form and can be used to document changes in the geomagnetic field through time. Thermoremanent magnetization is the most stable type of remanent magnetization in igneous rocks and can be carried by particle sizes above the upper size limit for single‐domain behavior. To better understand thermoremanent magnetization in particles larger than single domain, we imaged the thermal dependence of magnetic structures in ~1.5‐μm grains of titanomagnetite (Fe2.46Ti0.54O4) using variable‐temperature magnetic force microscopy. At room temperature, grains displayed single‐vortex and multivortex states. Upon heating, the single‐vortex state was found to be stable up to the Curie temperature (~215 °C), whereas multivortex states unblocked between 125 and 200 °C by transitioning into single‐vortex states. During cooling in a weak field (~0.1 mT), single‐vortex states nucleated just below the Curie temperature and remained unchanged to room temperature. The single‐vortex state was the only magnetic state observed at room temperature after weak field thermoremanent magnetization acquisition experiments. These observations indicate that single‐vortex states occur in titanomagnetite and, like single‐domain particles, have high thermal stability necessary for carrying stable paleomagnetic remanence.

Effects of Hf, Y, and Zr on Alumina Scale Growth on NiAlCr and NiAlPt Alloys

The effects of Hf, Y, and Zr additions on the growth of a thermally grown alumina scale formed on NiAlCr and NiAlPt alloys were investigated. Isothermal and thermal cycling oxidation experiments were carried out at 1150 °C, and cross sections of the oxidized samples were characterized using scanning electron microscopy. It was observed that single doping as well as co-doping of Hf, Y, and Zr reduces the rate of alumina scale growth on NiAlCr and NiAlPt alloys, with Hf showing a more significant effect than Y or Zr. The following possible contributing factors to these observations were assessed: (1) the ionic size of the minor alloying elements and (2) the bond strength between the doping elements and oxygen in the oxide grain boundaries in terms of formation and melting enthalpies of oxides. It was concluded that the bond strength between the doping elements and oxygen within the oxide grain boundaries plays an important role in retarding the alumina scale growth.

A multi-technique study of “barrier layer” nano-porosity in Zr oxides during corrosion and hydrogen pickup using (S)TEM, TKD, APT and NanoSIMS

We have used (S)TEM, TKD, NanoSIMS and APT to study nano-porosity in the oxide grown on deuterated Zr-1.0Nb and Zr-2.5Nb alloys. A detailed analysis of “barrier layer” nano-porosity by TEM and TKD has revealed that the oxide grain structure is much more disorganised and the nano-porosity network better developed in the rapidly oxidising post-transition alloy. Direct observations of the trapped deuterium (D) distributions from NanoSIMS analysis also shows much more penetration of the oxide layer post-transition. APT analysis shows that there is Fe and D segregation to some of the oxide grain boundaries with occasional evidence of porosity containing trapped D and H. We conclude that interconnected porosity would offer a dominant pathway for the transport of hydrogenic species to the metal substrate during the aqueous corrosion of zirconium alloys in service.

Inhibition of Ni Grain Growth in Ni-BCY Anode Substrate for Solid Oxide Fuel Cell

The growth of Ni grains in sintered 60wt%Ni–BCY anode supports for solid oxide fuel cells and their electrical conductivities were evaluated. The critical grain growth was confirmed in a Ni–BCY disk sintered at a temperature higher than 1450 °C, resulting in a large degree of decline in electrical conductivity. In addition, reducing the Ni content in Ni–BCY did not effectively suppress the Ni grain growth. Addition of GDCinto the Ni–BCY (Ni–BCY–GDC) was found to effectively inhibit the Ni grain growth after sintering at 1450 °C, which remarkably enhanced the electrical conductivity compared with those of the Ni–BCY supports. Adding GDC into BCY simultaneously suppressed the grain growth of the BCY. The grain sizes of Ni are in a linear relationship with grain size over volume fraction (r/f) of the oxide phase, implying that the Ni grain growth was prevented by the pinning pressure from the oxide grains.

Proposal of Granular-Type Cap Layer with High-$K_{u}$ CoPt Grains and Ferromagnetic Oxide Grain Boundaries for Full Granular Media

Investigation of magnetic properties and microstructure for the stacked media with Co80Pt20-30 vol% rare earth (RE) oxide (RE oxide: Gd2O3, Nd2O3, and Sm2O3) cap layers (CLs) deposited on a Co80Pt20-30 vol% B2O3 granular recording layer (GRL) was conducted. It was found that the employment of a granular-type CL with ferromagnetic oxide is effective to control intergranular exchange coupling of the magnetic grains in CoPt–B2O3 GRL while maintaining the granular structure of the CL. In this full granular media, continuous structure of columnar magnetic grains and grain boundaries from the GRL up to the CL can be observed. When a typical ferromagnetic oxide CL, such as CoPt–Gd2O3 (9 nm), is deposited on CoPt–B2O3 GRL (16 nm), the nucleation field is increased from 0.7 to 1.1 kOe, and the saturation field is reduced from 21.5 to 16 kOe which suggest that CoPt-RE oxide is promising for a CL.