Cr2O3 Concentration Research Articles

Enhancing UV light sensitivity of PVP polymer by doping chromium trioxide via the electrospun solutions

Herein, chromium trioxide (Cr2O3) doped Polyvinylpyrrolidone(PVP) nanofibers with high crystallinity and UV light sensitivity are successfully grown onto the glass substrates by electrospun deposition at room temperature. The effect of Cr2O3 concentration on the morphology, structure, and photoluminescence properties of the as-fabricated PVP nanofibers is examined. With the increase in doping concentration of Cr2O3 (i.e., 1, 2 and 3 %), the direct band gap of PVP nanofibers is reduced to 4.05, 4.01, and 3.85 eV, respectively. XRD and FE-SEM results manifest that the crystallinity and diameter of the nanofibers are dependent upon Cr2O3 concentration, i.e., the mean diameter decreases from 600 to 200 nm. Photoluminescence spectra indicate higher UV emission upon the addition of Cr2O3, with greater emission near the band edge for thinner nanofibers. A possible mechanism for the formation of PVP/Cr2O3 nanofibers is addressed in detail. Furthermore, it is found that the sensitivity of the as-fabricated PVP/Cr2O3 detector to UV-light emission strongly depends on Cr2O3 concentration, i.e., good responsivity (2.257 A/W) and specific detectives (9.8 × 1012 cm Hz1/2/W) at a Cr2O3 concentration of 2 % are achieved at a wavelength of 454.1 nm, besides recording the lowest rise and fall times.

Performance and properties evolution of near-term accident tolerant fuel: Cr-doped UO2

Chromium-doped UO2 fuel has received significant interest due to the ability for chromium to produce pellets with large average grain size (>30 μm), which has shown to increase fission gas retention during operation. Sintering of chromium-doped UO2 pellets was pursued with oxygen potential and sintering atmosphere controlled to tailor the final microstructure of the material. Chromium additions in this study ranged from 750 to 7800 ppm. Cr concentrations were studied pre and post sintering using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Effects of chromium content on lattice parameter and microstructure were examined with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Contraction of the UO2 lattice parameter was observed, as well as enlargement of grain size with increasing chromium content up to 4900 ppm Cr2O3. SEM indicated Cr incorporation within the matrix and the formation of chromium oxide precipitates throughout the microstructure at high Cr concentrations. Evaluation of thermophysical properties of Cr-doped UO2 pellets were conducted up to 1200 °C to illustrate their evolution with increased dopant concentration and microstructural changes. The results show that grain size is maximized at 52 μm with Cr2O3 concentration equal to 4900 ppm; however, grain size decreases at higher Cr2O3 concentrations. No significant changes were observed in specific heat capacity, linear thermal expansion, and coefficient of thermal expansion compared to undoped UO2. The thermal conductivity also decreased through the incorporation of Cr2O3 dopants above 750 ppm and is shown to be ∼15 % lower than reported UO2 values.

Influence of Cr2O3 Concentration on the Green Color of Flux Synthesized Emeralds Using the CIE1976 Color System

AbstractThe color of emeralds is predominantly influenced by the concentration of Cr3+. However, the evaluation of the trend of green color depth of emeralds, based on the practical single crystal synthesis with several instrumental analysis is not investigated in previous researches. Specifically, if the Cr2O3 content is controlled to be in the range of 0.2–0.4 wt%, then emeralds can be synthesized with the most esthetically pleasing color. Therefore, the effect of Cr2O3 concentration within the aforementioned range on the color of emeralds is studied using powder X‐ray diffractometry, digital microscopy, electron probe microanalysis, and micro‐spectrophotometry to understand how to achieve the most esthetically pleasing color. As a result, detailed behaviors relating to the absorbances, L*, a*, and b* values, and the relationship between the emerald crystal color changes and increases in Cr2O3 concentration are elucidated. Notably, the absorbance, L* and a* values change significantly when the Cr2O3 concentration is low (0.00–0.236 wt%). However, the changes in these values are moderate when the Cr2O3 concentration is higher (0.236–0.504 wt%).

Evaluation of Corrosion Resistance and Surface Film Analysis after Corrosion Testing of Materials Coated by Chemical Densified Coating Method under Boiling Sulfuric Acid Environment

For the purpose of developing metallic materials with excellent corrosion resistance under boiling sulfuric acid environment, the coated materials were evaluated for their corrosion resistance and the differences in surface morphology were investigated. As a result, the corrosion resistance of SUS304 coated and sintered eight times by chemical densified coating method (S-ZAC) was maintained at the point after 12h corrosion test, but the corrosion rate rapidly increased after 100h corrosion test. The cross-sectional microstructural analysis of the specimens showed that only a small amount of SiO2 remained on the surface, while Cr2O3 completely disappeared. The mechanism of film delamination in S-ZAC is assumed to be due to the thermal expansion caused by heating, which resulted in curvature of the thick film and cracks at the Cr2O3 and SiO2 interfaces. On the other hand, SUS304 coated with higher density of Cr2O3 by repeating the coating and sintering eleven times (MS-ZAC) showed excellent corrosion resistance as well as SiC even after 100h corrosion test. The results of cross-sectional microstructural analysis showed that MS-ZAC had higher Cr2O3 concentration, finer SiO2 grain size, and fewer porosity than S-ZAC. In particular, the mechanism of film maintenance in MS-ZAC is assumed to be the formation of a stacked structure in Cr2O3 particle layer, in addition to the thinning of the entire film.

Formation of electric spark WC-Co coatings with modifying Cr2O3 additives

Tungsten carbide coatings are widely used on steels due to their high hardness and wear resistance, but they have low high-temperature oxidation resistance and therefore need to be modified with oxidation resistance compounds. Electrode materials based on WC-8 %Co with addition of 1, 3 and 6 wt.% Cr2O3 were prepared by powder metallurgy for the deposition of electric spark coatings on steel 1035. An increase in the content of Cr2O3 in electrodes led to a rise in the thickness of the coatings from 18.2 to 28.3 µm. The tungsten semicarbide phase dominated in the structure of the coatings. The concentration of chromium in the coatings is a function of it in the electrodes. Polarization tests of coated samples showed an increase in the corrosion potential and a decrease in the corrosion current density with an increase of Cr2O3 concentration in WC-Co electrodes. The Cr2O3 additions into the WC-8 %Co electrode allow increasing the oxidation resistance of coatings at a temperature of 700°C. The coating microhardness increased monotonically from 9.6 to 13 GPa, the friction coefficient decreased from 0.7 to 0.58, and wear rate decreased with increasing Cr2O3 content. Electric spark deposition of the WC-8 %Co electrode with addition of Cr2O3 on steel 1035 allows increasing its wear resistance up to 14 times.

Structural and Compositional Features of Garnet-Containing Samples Synthesized in a System with Samarium at High Pressure and High Temperature

A distinctive feature of garnets associated with diamonds is specific containing of “light” rare earth elements. In the paper, the garnet-containing samples obtained at high pressure and high temperature in the system introduced with samarium (Sm) are studied. The experiments are carried out using a multianvil high-pressure apparatus of the “split-sphere” type (BARS) at a pressure of 5 GPa and a temperature of 1300 °С. The accuracy of measuring the pressure and temperature is ± 0.2 GPa и ± 25 °С, respectively. As a result, pyrope grains are synthesized with a CaO content no higher than 0.15 wt.% and Cr2O3 concentration within the range of 3.61-7.55 wt.%. The garnets are characterized by the stable presence of an impurity in the form of the Sm constituent. The garnets contain a significant amount of olivine inclusions. Crystals of the synthesized spinel are observed mainly in the interstices. This study demonstrates that the interaction of the components in the serpentine — chromite — corundum — Sm system leads to the crystallization of pyrope garnet, which forms large intergrowths of individual grains. The zoning observed in garnet is due to the transfer of components by fluid during the experiment. It is concluded that the Sm content in garnet can significantly increase depending on its content in the system.

Effect of Cr2O3 on the crystallization, structure, and properties of Ti-bearing blast furnace slag-based glass ceramics

ABSTRACT The effects of Cr2O3 on the crystallization, structure, and properties of Ti-bearing blast furnace slag-based glass ceramics were investigated. The results show that the transition temperature and crystallization temperature decreased with introduction of Cr2O3 as a while. Specifically, the crystallization temperature first decreased, then increased with the increase Cr2O3 concentration from 0.2 wt% to 0.8 wt%, and finally decreased with further increased in Cr2O3 concentration. The crystal phases were identified as anorthite, diopside, and akermanite. As the content of Cr2O3 increased to 0.8 wt%, the dendrites gradually decreased and the granular crystals gradually increased. When the Cr2O3 concentration further increased, the number of granular crystals gradually decreased and the dendrites gradually accumulated. With the increase of Cr2O3 from 0.2 wt% to 0.8 wt%, the structure of the investigated glass gradually depolymerized, while the opposite trend was presented with further increased in Cr2O3 content. With increasing Cr2O3 content from 0.2 wt% to 2 wt%, the flexural strength values and Vickers hardness values of the glass ceramics first increased and then decreased, and the maximum values of flexural strength and Vickers hardness were obtained as 94.371MPa and 974.43MPa, respectively. The prepared Ti-bearing blast furnace slag-based glass ceramics showed good acid and alkali resistance.

An evaluation of tri-valent oxide (Cr2O3) as a grain enlarging dopant for UO2 nuclear fuels fabricated under reducing environment

A study was performed to evaluate the microstructure and crystallography of nominally 500–2000 Cr2O3-doped UO2 fabricated in a temperature range of 1150–1750°C under reducing experimental conditions. An increase in grain size of the samples was observed with the increase in heat treating temperature as expected. For a given sintering temperature (1700–1750°C), an increase in the grain size was also observed with the increase in Cr2O3 concentration up to a value of ~1000–1200 wppm. A decrease in fission gas release as a function of grain size was estimated for the Cr2O3-doped UO2 samples assuming specified post-irradiation annealing conditions. A nearly linear decrease was obtained in the lattice parameter of the Cr2O3-doped UO2 fcc phase with the increase in Cr2O3 concentration, especially up to a nominal value of 1000 wppm. The lattice parameter decrease was also persistent with the increase in the average grain size as a result of addition of Cr2O3 into the UO2 lattice. An increase in the crystallite size and a decrease in the microstrain of the fcc phase were observed with the increase in the average grain size of the samples, indicating a higher crystallinity of the Cr2O3-doped samples than that of the undoped UO2 sample.

Experimental study on the effects of H2O upon crystallization in the Lower and Critical Zones of the Bushveld Complex with an emphasis on chromitite formation

Mafic–ultramafic layered rocks of the Lower and Critical Zones of the Bushveld Complex are believed to have formed from a parental magma usually labelled B1 with SiO2 content at 55 wt.%, MgO at about 12 wt.% and Cr2O3 concentration at 0.15 wt.%. Previous experimental study at 300 MPa and nominally dry conditions showed that this composition had orthopyroxene on liquidus between 1250 and 1300 °C, and the mineral was joined by plagioclase and clinopyroxene at and below 1166 °C. The objective of this study was to investigate the effects of variable additions of H2O (2, 4 and 6 wt.% in starting compositions) on liquidus and sub-liquidus phase equilibria. Main attention was given to the solubility of Cr-spinel and Cr distribution between melt and crystalline phases. Six experiments were carried out in the internally heated pressure vessel (IHPV) at 300 MPa and in the temperature interval 1100–1300 °C. Redox conditions were not controlled and thermal dissociation of the H2O component followed by hydrogen diffusion through container walls resulted in a noticeable oxidation of run products. The effective values of fO2 in experiments were calculated using SPINMELT 2.0 software bases on the regression of experimental data on the spinel-melt equilibrium. According to the calculations, H2O additions in isothermal series of experiments increased fO2 by 0.8–1.6 log-units from the level in a nominally dry run. Overall, the experiments showed that H2O additions suppressed crystallization of silicates, shifted olivine-orthopyroxene peritectic equilibrium towards higher olivine stability (olivine first appears in H2O-bearing compositions at 1175 °C) and increased the proportion of magnetite component in spinel solid solution. The addition of 4 wt.% H2O to the starting composition at 1200 °C resulted in complete melting of orthopyroxene, which left Cr-spinel as the only liquidus phase. Equal amount of H2O at 1125 °C leads to complete melting of plagioclase, orthopyroxene and clinopyroxene, which leaves only olivine and spinel stable and increases the liquid mass fraction from 0.62 in the nominally dry compositions to 0.9. The results of this study appear to support the idea that chromitite layers in the Critical Zone of the Bushveld Complex were formed by episodes of hydration melting of silicate cumulates.

A new modeling of the dissolution of chromia in Na2O-SiO2 liquids

A model of dissolution of chromia in binary Na2O-SiO2 liquids is presented in this work. Data available in the literature on the acid/base properties and the chemistry of chromium in such liquids were used in order to refine the model. Physical phenomena such as migration of ions and the resulting electric field, the mechanical equilibrium of the liquid and the interface recession caused by the dissolution of chromia are also implemented in the model. Numerical simulation has been compared to experimental measurements of Na2O, SiO2 and Cr2O3 concentration profiles after 1 h of immersion of chromia in a (Na2O)0.25(SiO2)0.75 liquid at 1150 °C. The phenomena having a significant influence on the dissolution rate of chromia are highlighted in the last part of this paper.

Vitrification and Crystallization Behavior of CaO-SiO2-MgO-Al2O3-Fe2O3-Cr2O3 System

The effect of basicity and Cr2O3 content on vitrification of the CaO-MgO-SiO2-Al2O3-Fe2O3-Cr2O3 system during a melt-quenched process and the crystallization and mineralogical evolution of the obtained glasses were investigated. X-ray diffraction (XRD) analysis of the quenched samples indicated that lower basicity (B = 0.8 and 1.0) and lower Cr2O3 concentration (< 4 wt pct) were favorable for glass formation. B = 1.25 and 1.5 samples were crystallized much easier, with most of the Cr captured in the spinel structure. Differential scanning calorimetry measurements revealed that the glass transition and crystallization temperatures both increased upon increasing the heating rate from 5 K to 20 K (°C)/min. In addition, compared with the samples without Cr2O3, the crystallization activation energy of those with Cr2O3 were lower for the same basicity. For glassy samples heated above 1228 K (955 °C), XRD and scanning electron microscopy characterizations suggested that diopside and wollastonite were the main precipitated phases for the samples with B = 0.8, whereas akermanite and wollastonite were the main phases for samples with B = 1.0.

Reoxidation of Al-Killed Steel by Cr2O3 from Tundish Cover Flux

Reoxidation has long been a problem when casting ultra-low oxygen liquid steel. An experimental study of the reoxidation phenomenon caused by Cr2O3-bearing cover flux of Al-killed steel is presented here. MgO-CaO-SiO2-Al2O3-Cr2O3 tundish cover flux with various Cr2O3 contents were used to study the effects of Cr2O3 on total oxygen content (T[O]) and alumina and silicone loss of Al-killed steel at 1923 K (1650 °C). It was found that Cr2O3 can be reduced by Al to cause reoxidation, and the reaction occurs mainly within 2 to 3 min after the addition of the tundish cover flux with 5% and 10% Cr2O3 concentration. T[O] and Al loss increase with higher Cr2O3 concentration flux. Two controlled experiments were also made to investigate the oxygen transported to the steel by the decomposition of Cr2O3. It was calculated that when Al is present in steel, more than 90% of the reoxidation of Cr2O3 is caused by Al, and the rest is caused by decomposition.

Luminescence and EPR properties of high quality ruby crystals prepared by the optical floating zone method

Rubies (Cr: Al2O3 single crystals) with 0.025–0.4 mol% Cr2O3 were prepared by the optical floating zone method, and characterized by X-ray diffraction (XRD), electron paramagnetic resonance (EPR) spectroscopy, optical transmission and photoluminescence (PL). Crystals were free of inclusions and cracks, and had high transmittance in the visible region. In addition to the well-known signals from Cr3+ in the α-Al2O3 structure, the EPR spectra indicated the presence of very weak signals, which may correspond to paramagnetic centres associated with an oxygen vacancy, and an electron-loss oxygen centre, O−. The concentration of these paramagnetic centres was at a minimum for Cr2O3 concentration of 0.15 mol%, and additional Cr3+-derived peaks were also observed with Cr2O3 concentrations >0.15 mol%. The PL spectra also varied with Cr2O3 concentrations; the emission intensities of the PL spectra increased with Cr2O3 concentration for concentrations ≤0.15 mol%, then decreased with the further increases in Cr2O3. Thus the maximum luminescence emission intensity and the minimum concentration of paramagnetic structural defects were observed with 0.15 mol % Cr2O3, and the presence of additional interactions involving Cr3+ ions may contribute to the partial quenching of the luminescence at higher Cr3+ concentrations. Overall, the optical floating zone method represents an effective and economic approach to the preparation of high quality rubies, and their optimum optical properties were observed with Cr2O3 concentrations of 0.15 mol%.

Cr3+ doped NaF–ZrO2–B2O3–SiO2 glass ceramic materials for optoelectronic device application

The glass materials of composition (25-x)NaF–5.0ZrO2–10B2O3–60SiO2: x Cr2O3 (0 ≤ × ≤ 0.5) were synthesized. Structural (XRD, SEM, EDS and DTA), optical (optical absorption and photoluminescence), DC conductivity and dielectric investigations of all these glass ceramic materials were studied. Different physical parameters such as density (ρ), refractive index (μ), polaron radius (ri), field strength (Fi), optical basicity (Λth) and molar volume (Vm) were calculated. The glass transition temperature (Tg) and glass crystallization temperatures (Tc) of these materials were recorded by using DTA studies. The decrease in the value of theoretical optical basicity with increasing Cr2O3 concentration of the present glass ceramic materials suggests the increase in covalence. Various optical parameters such as bandgap (Eo), nephelauxetic ratio (β), transition probability (A) and emissive cross-section (φ) were calculated. Different dielectric parameters such as density of states near Fermi level, activation energy for dipoles and temperature region of relaxation were also calculated. The observed studies suggest that these materials are suitable for both optical and electronic device applications.

Grain refinement and non-ohmic properties in (Co, Ta)-doped SnO2 ceramics by Cr2O3 additions and the in situ formation of CoCr2O4

In this investigation, the microstructure and current–voltage properties of (Co, Ta)-doped SnO2 ceramics were found to depend on Cr2O3 additions. SnO2–Co3O4–Ta2O5 ceramics with additions of 0, 0.05, 0.1, 1 and 2 mol% Cr2O3 were sintered at 1350 °C under an oxidizing atmosphere and characterized microstructurally and electrically. Characterization by XRD and SEM shows that for samples with 0–1.0 mol% Cr2O3, the microstructure consists of single-phase SnO2 grains, while for the sample with the highest Cr2O3 content, the CoCr2O4 spinel phase is present in SnO2 microstructure. Moreover, reduced grain size distribution breadth and average grain size are observed in the SnO2 microstructure with 2 mol% Cr2O3. Results suggest that nonlinearity coefficient (α) is not as sensitive as electric field at fixed current density (EB) to Cr2O3 concentration changes.

Structure of glass-ceramic from Fe-Ni wastes

Hazardous residues from ferronickel production and glass cullet were mixed and vitrified. After low-cost heat-treatment the obtained glass was transformed in a fine-crystalline glass-ceramic. The evolution of structure during the crystallization cycle is studied by XRD and SEM-EDS. Finally, the morphology of final glass-ceramic was elucidated by TEM and FESEM.Due to the elevate amounts of iron and magnesium oxides and the presence of ∼2 wt % chromium oxides in the composition, the crystallization process is peculiar and the final structure of glass-ceramic is complex. Some preliminary Fe-Mg-Cr spinel crystals with size of few microns precipitate during the melt cooling. Then, these crystals act as centres for the growth of a pyroxene phase; thus, 15–20 vol% of the glass-ceramic structure is formed. The major amorphous phase, where Cr2O3 concentration becomes negligible, is characterized with a high immiscibility trend, leading to the formation of Fe-rich droplets with size of 50–70 nm. Subsequently, these droplets are transformed into nano magnetite crystals, which provoke crystallisation of the main pyroxene phase. This “second” new pyroxene phase differs by the one, already formed on the preliminary Fe-Mg-Cr spinel, and is composed by mono-crystals with size of 150–200 nm.

Influence of Cr2O3 on electrical and microstructural characteristics of ZnO–V2O5–MnCO3–Nb2O5 varistor ceramics

In order to clarify the controversy on whether Cr2O3 can enhance the nonlinearity of ZnO based varistor ceramics, ZnO–V2O5–MnCO3–Nb2O5 (ZVMN) ceramics with 0-0.5 mol% Cr2O3 were synthesized by traditional mixing oxide procedure ended by sintering at 900 °C for 3 h. Then XRD, FESEM, EDS and V–I tests were used to investigate the influence of Cr2O3 on electrical and microstructural characteristics of the obtained ceramics. The result shows ZVMN ceramics with Cr2O3 addition consisted of Zn3(VO4)2, ZnV2O4 and ZnCr2O4 as the minor secondary crystalline phases and ZnO as the main phase. The average size of ZnO grains decreased monotonously with the increase of Cr2O3 concentration from 0 to 0.5 mol%, which in turn led to a monotonous elevation of the breakdown field from 354 to 1032 V/mm. The nonlinearity coefficient of ZVMN ceramics increased to its maximum value of 41.0 at 0.1 mol% Cr2O3, while the breakdown field and leak current density were 415 V/mm and 95.0 μA/cm2 respectively. The comparison of this study with those of peers suggests Cr2O3 is more likely to enhance the nonlinearity of ZnO–V2O5 based varistor ceramics than it does in the case in ZnO–Bi2O3 system, wherein co-doping Sb2O3 may be a necessary step to secure an overall enhancing effect of Cr2O3 on the nonlinearity.

The Phase Transition of Corundum-Eskolaite Mineral Series Probed by X-Ray Absorption Spectroscopy

The red color of ruby is caused by Cr3+ impurities substituting Al3+ in Al2O3 structure. The complete substitution of Al3+ by Cr3+ produces Cr2O3 that has the green color. In this study, we focused on the phase transition of solid solution between corundum (Al2O3) and eskolaite (Cr2O3) mineral series. A series of Al2O3-Cr2O3 samples were prepared by mixing fine powder of Al2O3 and Cr2O3 in various ratios. They were ground together and then recrystallized. The obtained crystals were ground again in powder form for X-ray absorption near edge structure (XANES) measurements to avoid polarization dependence. The measurements were carried out at the Cr K-edge absorption energy using a 13-channel array Ge detector in the fluorescence mode. The XANES spectra showed line-shape transitions for 0.125 to 100% variation of Cr2O3. Significant variations in transitions were found when the Cr2O3 content was between 20% and 80%. With Cr2O3 concentration increasing, the sample colors apparently turned from pink to dark green. CIELAB color index measurements were performed. The variations of line-shape spectra of the Al2O3-Cr2O3 samples were found to be consistent with the CIELAB color index results. This Cr K-edge XANES study could be useful for the research in mineral sciences.

The comparative study on nanostructured tribolayers of Alloy 690TT subjected to fretting wear under different oxygen contents

The nanostructured tribolayers of Alloy 690TT subjected to dry fretting wear at 320°C under different oxygen contents were studied. Results indicated that the low oxygen content (5vol%) produced the nanostructured tribolayer containing large amount of Cr2O3 with an average grain size of 15nm, which was mainly due to the limited oxidation and preferential oxidation of Cr, resulting in lower friction coefficient, wear volume, dissipated energy, smoother worn surface and thicker tribolayer. The farther from the worn surface, the weaker was the Cr2O3 concentration. Only a small quantity of microcracks perpendicular to the worn surface were observed in the Cr2O3-rich tribolayer under a low oxygen content, which indicated the Cr2O3-rich tribolayer had a better wear resistance. By comparison, under a high oxygen content (21vol%), the tribolayer mainly consisted of NiCr2O4 and Fe2O3 with an average grain size of 7nm due to the sufficient oxidation during fretting wear, resulting in higher friction coefficient, wear volume and dissipated energy. The plenty of microcracks without specific orientation and voids appeared in the oxide layer and along the interface of oxide/metallic grains.

Synthesis, structure and dielectric properties of nanocrystalline SnO2–CoO–Nb2O5 varistor doped with Cr2O3

The effect of Cr2O3 on the microstructure and dielectric properties of SnO2 varistors doped with Nb2O5 and CoO was investigated. The density of ceramic samples was calculated and found increases from 6.6819 to 6.8704 g cm−3. It is observed in this figure that, independent of the Cr2O3 concentration, no other crystalline phase besides SnO2 is observed indicating that the system is single phase within the detection precision of the X-ray diffraction. The average crystallite size of the prepared samples using was estimated Scherrer’s equation. A scanning electron microscope (SEM) was utilized in order to study the effect of variation of Cr2O3 content and its impact on the microstructure and electric properties. The obtained results show that, as Cr2O3 concentration increases the dielectric permittivity increases and ac resistivity decreases and then increases and takes it maximum resistivity at 0.5 mol%. The compositional dependence of the dielectric permittivity and ac resistivity has been explained in the light of the SEM micrographs. The obtained results show also that the sample of 0.5 mol% of Cr2O3 has highest resistivity and consequently low dielectric loss. So, it can be used in some technological applications such as transformer and inductor cores.