ZrO2 Samples Research Articles

Protocols for bulk off-line fluid inclusion extraction for the analysis of δ13C-CH4 and δ13C-CO2 using a cavity ring-down spectroscopy (CRDS) analyser

Fluid inclusions are a window into deep geological fluids, providing unique access to their nature and composition. The isotopic composition of CO2 and CH4 hosted in fluid inclusions is a powerful proxy to assess the origin and transformation of deep geological fluids, giving insights into carbon sources, fluxes, and degassing in a wide variety of geodynamic settings. Over the last 5 decades, techniques have been developed to extract fluid inclusions from their host minerals and measure their bulk composition. These techniques are often challenged by analytical artifacts including high blank levels of CO2 and CH4, fluid re-speciation, gas adsorption, and diffusion. Since these processes may alter the pristine composition of gases liberated from fluid inclusions, rigorous protocols are needed in order to evaluate the isotopic integrity of the extracted volatile species. In this study, we introduce new protocols for bulk off-line fluid inclusion extraction for the analysis of δ13C-CH4 and δ13C-CO2 using a Cavity Ring-Down Spectroscopy (CRDS) analyser (Picarro G2201-i). Two mechanical fluid extraction techniques are compared: ball milling in ZrO2 jars and sample crushing in a stainless steel sealed tube under a hydraulic press. Blanks and isotopically labelled tests with the ball milling technique suggest that rotation speed, grinding stock filling degree and filling type alter the CH4 and CO2 concentrations and isotopic compositions measured by the CRDS analyser. In contrast, the crushing technique does not generate measurable quantities of blank CH4 and CO2. The protocols presented in this study allow to extract, detect, and analyse δ13C of CH4 and CO2 for concentrations above 10 and 1,000 ppm respectively. Interlaboratory experiments allowed to replicate previously measured δ13C-CH4 values in natural fluid inclusions within 1‰ with both extraction techniques. This study highlights the potential of combining simple bulk off-line fluid inclusion extraction techniques with a CRDS analyser for δ13C analysis of CO2 and CH4 without gas separation being required.

Fabrication of Ni–ZrO2 nanocomposites through a new electroforming bath and Assessment of their morphology, wear, and corrosion resistance

Nowadays, researchers are looking for ways to produce complex tools and pieces with high precision at a low cost. In recent decades, electroforming has been an important and stable technique for producing composite parts. In this research, Ni–ZrO2 nanocomposite foils were fabricated by using a nickel-chloride bath through electroforming, a bath not previously utilized for this purpose. In this study, the effects of ZrO2 concentration and direct current density on the volume percentage of ZrO2 nanoparticles and the grain size of the nickel matrix of foils are also investigated. The sample with 13.65 vol % nanoparticles had the highest volume percentage and the minimum nickel grain size of 516.9 nm, which is almost 46 % smaller than the grain size of pure nickel foil. The wear and corrosion behavior of the foils were examined using a pin-on-disk wear test, potentiodynamic polarization, and impedance spectroscopy analysis. The results showed considerable improvement in the wear and corrosion resistance of the Ni–ZrO2 samples compared to the pure electroformed nickel. The nanocomposites exhibit a lower friction coefficient than pure nickel, with a maximum reduction of 44 %. A composite specimen of Ni–ZrO2 had 2.5 % lower corrosion density and 596 % higher charge transfer resistance compared to pure nickel. It was concluded that the nickel-chloride bath has an excellent potential to produce composite nickel foils with acceptable brightness, satisfactory wear, and corrosion resistance.

Effect of the Crystalline Phase Type on the Thermoluminescent Response of ZrO2 Due to Different Synthesis Methods

ZrO2 samples were obtained using three different synthesis methods (Calcination, Co-precipitation and Hydrothermal). The samples were characterized to analyze the effect of the crystalline phase on their thermoluminescent (TL) and photoluminescent (PL) responses. The ZrO2 phase was analyzed by X-Ray diffraction (XRD) and Raman. Nanoparticle size distribution was obtained by scanning electron microscopy (SEM). For optical analysis, characterizations included absorbance measurements, where samples exhibited modifications in color centers, PL emission and experimental fluorescence lifetime decay ([Formula: see text] measurements. Additionally, their TL response was studied under UV (245[Formula: see text]nm and 385[Formula: see text]nm), and 6[Formula: see text]MV photon energy from LINAC excitation. The obtained results show the improvement of TL and PL properties due to ZrO2 phase while an amorphous ZrO2 synthesized by hydrothermal method is an excellent prospect to be used as TL material and it may be a promising scintillator material at 254[Formula: see text]nm.

Role of Zr3+ in excitation of Eu3+ ions in stabilized ZrO2:Eu nanoparticles

Microwave hydrothermal technique has been applied to crystallize ZrO2 nanoparticles with the sizes below 10 nm and activated with Eu. Trivalent europium ions acted also as the stabilization agent of the high temperature ZrO2 polymorphs at the room temperature. To achieve this, high concentrations - up to 20 % of Eu3+ - were introduced to the zirconia host lattice. Reference samples of ZrO2 containing yttrium were synthesized to obtain pure cubic, tetragonal and monoclinic phases at constant europium concentration. Eu3+ ions have not been reduced to divalent form, however, we have observed reduction of Zr4+ ions by means of luminescence spectroscopy and electron paramagnetic resonance (EPR). The variation of Zr3+ concentration in the samples with increasing Eu3+ content seems to support the concept of trivalent ion pairs as charge compensation centers in ZrO2. Excitation of Eu3+ ions was conducted via low and high symmetry sites. Trivalent zirconium ions have been found to play a role in the excitation of Eu3+ ions at low symmetry sites.

Synthesis and Spectroscopic Investigations of Sm3+ Activated ZrO2 and Na2ZrO3 as Warm Light Phosphors.

In this work, we investigate how the structural and optical characteristics of ZrO2 and Na2ZrO3 are influenced by Sm3+ ion doping. Urea-assisted combustion approach is employed by varying the molar concentration of Sm3+ ions in both the host lattices. XRD pattern revealed the monoclinic crystal system for both samples. XPS investigation has been examined to acquire the chemical information of the samples. FESEM is used to identify the morphology of the samples. The optimum molar concentrations of Sm3+ doped ZrO2 and Na2ZrO3 phosphors, as per photoluminescence (PL) findings, are 1.5mol% and 2mol%, respectively. CIE coordinates of ZrO2:Sm3+ and Na2ZrO3:Sm3+ are found to be (x = 0.59, y = 0.41) and (x = 0.61, y = 0.39) that corresponds to the amber region of color gamut. The optical bandgap for the synthesized samples is estimated using the UV-Vis diffuse reflectance spectra and the obtained values for the optimal concentration of dopant (Sm3+) in the ZrO2 and Na2ZrO3 samples are 4.61 and 4.94eV, respectively. The findings of the study reveal that the synthesized phosphors may be utilized as warm light phosphors and be a promising candidate for amber light-emitting diodes (LEDs).

Advancing solid-state lithium phosphate electrolyte: Synthesis and characterization of Li2NaPO4–ZrO2 nanocomposites for solid-state batteries

Lithium phosphates are one of the most promising groups of inorganic solid electrolytes under investigation owing to their excellent Li-ion conductivity. A series of compositions with different weight percentages of (1-x) Li2NaPO4-(x) ZrO2 samples have been prepared by the solid-state technique and characterized by FT-IR, XRD, SEM-EDS, TEM, and Impedance Spectroscopy. Among the various compositions, 20 wt % ZrO2 exhibits the highest ionic conductivity, i.e., σ = 4.5 × 10−3 Scm−1, and the lowest activation energy 0.0759 eV at 298 K. XRD analysis reveals that the addition of ZrO2 nano-filler up to the optimum value of 20 wt % suggests the formation of the amorphous phase. SEM micrographs reveal that the introduction of ZrO2 nanofiller reduces the crystallinity of the Li2NaPO4 and enhances the ionic conductivity compared with pure Li2NaPO4. Our study marks substantial advancement in the synthesis of innovative nanocomposite solid electrolytes for batteries with superior energy storage capacities.

Design of porous ZrO2 with well-tuned band structures and strong visible-light harvesting via Zn doping for enhanced visible-light photocatalysis

As one of huge-gap semiconductors, zirconium dioxide (ZrO2) has been emerging as one of popular photocatalysts for treating wastewater, and the band gap engineering of ZrO2 for efficient visible-light harvesting and high-performance photocatalysis is probably the most important challenge. In this work, porous Zn doped Zr3+-ZrO2 nanostructures with strong visible-light harvesting capacity were fabricated via a calcination process for tetracycline degradation. The obtained (Zn, Zr3+)-ZrO2 samples showed greatly narrowed band gaps and enhanced visible-light harvesting capacity. In addition, the photocatalytic performance of the (Zn, Zr3+)-ZrO2 nanostructures was studied with tetracycline degradation as a model reaction. Among these prepared samples, the optimal (Zn, Zr3+)-ZrO2-5% sample exhibited remarkably improved tetracycline degradation visible-light irradiation, and the apparent rate constant reached 0.04958 min−1, which was 7.05 times of pristine Zr3+-ZrO2. The boosted photocatalytic performance of the (Zn, Zr3+)-ZrO2 nanostructures were mainly ascribed to Zn doping effects as along as the high surface areas. Finally, possible photocatalytic mechanism, degradation pathways, and toxicity assessment were also studied. Current results indicate the significant roles of Zn doping in regulation of band gaps and morphology control of ZrO2 for high-performance photocatalytic applications.

Periodic oxygen-defective ZrO2−x films with room-temperature ferromagnetism produced by precisely controlling oxidation of metallic Zr foil

Ferromagnetism can be induced by introducing oxygen vacancies into metallic oxides. The oxygen deficiencies introduced into ZrO2 samples thus far have been present in unquantifiable concentrations and randomly scattered near the surface. We successfully produced room-temperature-ferromagnetic 9 μm-thick ZrO2−x films via a stepwise oxidation process consisting of annealing metallic Zr foil in air and under a controlled oxygen partial pressure. The ZrO2−x films are composed of a periodic structure with a spacing of 3–4 nm; this structure originated from the presence and absence of oxygen deficiencies. The unique structure in the ZrO2−x phase consisting of the periodic arrangements of oxygen deficiencies can be produced by the stepwise oxidation using Zr metal. Our proposed process should open the door for new applications of defect-driven ferromagnetic films of undoped magnetic oxides with a periodic oxygen-defective structure.

Morphology and formation mechanism of cracks in Al2O3–ZrO2 eutectic ceramics fabricated via laser powder bed fusion

AbstractThe cracks in Al2O3–ZrO2 eutectic ceramics produced by laser powder bed fusion (LPBF) have a significant impact on their practical applications in various industries. In order to understand the factors influencing crack formation, a systematic study of the characterization and propagation of cracks in single‐track, multi‐track, and bulk samples by varying the process parameters has been carried out in this research. The results showed that parallel cracks can be healed by reducing the scanning spacing and scanning length. Additionally, it was found that using a modest scanning speed and a shorter length can minimize the accumulation of thermal stress, resulting in the suppress crack formation. Based on this conclusion, a crack‐free Al2O3–ZrO2 eutectic ceramic sample was finally obtained under the optimized parameters with the power of 100 W, the scanning speed of 100 mm/s, the hatch spacing of 100 μm, the scanning length of 3 mm, and the layer thickness of 50 μm. Additionally, three typical microstructures, including eutectic, cellular, and dendritic structures, were identified in the LPBF‐fabricated Al2O3–ZrO2 samples. The cellular microstructure showed improved crack inhibition capability due to the deflection and pinning effects. Cracks expand more easily in dendritic and eutectic microstructures, where anisotropy is more prominent.

Production and tribological performance under sliding contact conditions of zirconia and reduced graphene oxide loaded polymer nanocomposites for biomedical applications

AbstractThis work targets the production of novel biomaterials and an optimized process to disperse Zirconia (ZrO2) and reduced graphene oxide (rGO) in the ultra‐high molecular weight polyethylene (UHMWPE) matrix. The mechanical and wear performance of the developed samples were evaluated through compression and tribological tests utilizing a bio‐tribometer. The developed samples are tested under simulated body fluid (SBF) lubricating media. In particular, the hybrid material is made of 5 wt% zirconia and 1 wt% rGO have an enhanced compression modulus of 0.29 GPa. This indicates a 26.08% improvement over pristine UHMWPE. Besides this, the compressive strength of this hybrid material is about 46.75% higher than that of pristine UHMWPE. The gray theory provided optimum settings as 1 wt% rGO and 5 wt% ZrO2 fillers are loading with 60 N load and 900 sec cycle time. The long‐range organized lamellar structures and microfibers were formed between the crystals with the help of the graphene layers. The inclusion of rGO nanofillers (1 wt%) and zirconia improve the wear resistance, which signifies the best‐desired values for coefficient of friction (Cf) and Specific wear rate (Wr). Improved loading conditions for prosthetics and implant components are possible with modified UHMWPE.Highlights This work highlights the tribological performances of hybrid nanocomposites. The effect of rGO and ceramic (ZrO2) nanofillers on UHMWPE was examined. Zirconia/rGO enhanced bio‐inert, wear‐resistant and biocompatibility. Compared to pristine, 1 wt% rGO and 5 wt% ZrO2 sample shows better results. Orthopedic and dental prostheses may be made using hybrid nanocomposite.

2D g-C3N4 nanosheets functionalized with nickel-doped ZrO2 nanoparticles for synergistic photodegradation of toxic chemical pollutants

The photocatalytic removal of toxic chemical pollutants from wastewater has garnered significant attention in recent times owing to its notable removal efficiency, cost-effectiveness, and eco-friendly characteristics. Nonetheless, this catalytic process necessitates augmented charge separation and distinctive interface properties to facilitate catalytic reactions for water treatment applications. Therefore, in the current study, novel g-C3N4/Ni-doped ZrO2 heterostructured hybrid catalysts have been synthesized via a hydrothermal approach. Microscopic studies reveal that ZrO2 nanospheres were distributed on the layered-like 2D structure of g-C3N4 nanosheets. Electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (UV-DRS), and photoluminescence (PL) characterizations were employed to investigate the impact of bandgap, electron-hole recombination, charge transfer, and interface properties on the catalytic performance of g-C3N4/ZrO2 hybrids. XRD analysis confirmed that the Ni-ions do not disturb the host lattice crystal structure and heterostructure development between g-C3N4 and doped ZrO2 sample. Structurally, Ni-doped nanoparticles were found to be equally superficially dispersed on g-C3N4 sheets. Optical analysis results suggest that the hybrid catalyst possesses a narrow bandgap of 2.56 eV. The synthesized photocatalyst degraded rhodamine B (RhB) and tetracycline (TC) with ∼92% and ∼89% degradation efficiency, respectively. Heterostructured hybrid catalysts showed superior degradation rate constants than other catalysts. This might be attributed to the sufficient separation of electron-hole due to the development of a heterojunction. The radical scavenging experiments suggested that O2●- and ●OH radicals contributed substantially to the dye elimination activity of the composite. Therefore, the synthesized novel nanohybrid catalysts in this study present an efficient and straightforward synthesis method for the efficient removal of toxins from wastewater under visible light irradiation.

Interaction of SiC with Al2O3−(t + m)ZrO2(Y2O3) Oxide Composition

We employed contact alloying in the range 1000–1860°С to study the reaction specifics between SiC and Al2O3−(t + m)ZrO2(Y2O3) oxide composition. Real-time experiments with photographic recording of the changing size and shape of the Al2O3−(t + m)ZrO2(Y2O3) sample on a SiC ceramic substrate showed that Al2O3−(t + m)ZrO2(Y2O3) compositions react with the silicon carbide substrate in the range 1720–1860°С to melt and penetrate into (impregnate) the substrate. X-ray powder diffraction patterns were measured for samples taken from the contact area of the oxide composition with SiC directly on the substrate and in a chipped-off 1-mm-deep near-surface layer. ZrС, Al2Y4O9, and Al3.21Si0.47 were formed in the contact area via redox reactions involving oxide melt, in addition to 6H-SiC, Si and Al2O3, t-ZrO2 phases, which are the initial components of the substrate and oxide composition, respectively.

Synthesis and characterization of some Cr-Zr and Cr-Zr-O nanostructures

The co-depositions of Cr-Zr and those of Cr-Zr-O coatings of 500 nm thick were made using magnetron sputtering in continuous mode, in a circular enclosure with a volume of 0.05 m3 evacuated prior to the deposition process under 10-6 mbar vacuum conditions. Silicon and Carbon substrates measuring 12x15mm were used for deposition. The topology of all of the CrZr and CrZrO2 coatings deposited on silicon and carbon substrates have been investigated by Scanning Electron Microscopy (SEM) at three magnifications: 1000x, 5000x and 10.000x. For all of the coatings deposited on Silicon substrates, at all three magnifications, was observed very smooth surfaces with only small topological elements. In some samples, few droplets of around 100nm can be observed. The appearance of particulates is caused by the arching events that occur at target surface during the deposition proces and are more pronounced during reactive sputtering. The coatings deposited on the Carbon substrate show more morphological features as these substrates have a lower grade surface polish finish as to sliced Silicon wafers; the deposited film tends to follow the substrate topology and cracks can be seen on the surface. Were investigated the mechanical properties of the samples of Cr+Zr, respectively Cr+Zr+O2 using The Bruker Hysitron TI 980 TriboIndenter which allows to extrapolate mechanical properties such Young’ s Modulus (YM) and Hardness (H). The experimental results obtained through nanoindentation studies, show: In the absence of oxygen during deposition ( Zr-Cr structures), the Young’s Modulus and Hardness are influenced by the concentration ratio of the two components Cr and Zr, i.e., there is the practical possibility of adjusting the two parameters YM and H by correspondingly changing the concentrations of the components of the structure . In the case of the Cr+Zr+O2 structures, for sample where the concentration of Chromium is maximum and the concentration of Zirconium is minimum, the presence of Oxygen causes a decrease for YM and respectively a decrease for H (in this case Cr-O bonds are predominant). In the case of sample in which the concentration of Zirconium is maximum and the concentration of Chromium is minimum, in the presence of Oxygen (now the bonds Zr-O being predominant), an increase for YM and an increase for H are observed. The crystalline structure was investigated using X-Ray Diffraction (XRD) method, using a setup composed of a diffractometer equipped with a Cu-Kα X-ray sourse, with a specific wavelength of 0.154nm, in a Bragg-Bretano type geometry. In the case of the Cr-Zr sample, diffractograms show that only the peaks corresponding to the Si substrate are visible, highlighting the amorphous character of the structure. Also, the measurements reveal the amorfous character of the Cr-Zr-O sample. In order to highlight the effect of the element Cr together with Zr and O, the diffractogram of the ZrO2 sample and diffractogram of Cr-Zr-O sample are examinated for comparison. Considering the application of these materials in dentistry, the 2 wide amorphous strips in the case of ZrO2 sample and amorfous character found in the case of Cr-Zr-O sample, could correspond to the adhesive used to attach the veneer to the tooth of such structures. From this perspective, it can be stated that the presence of the Cr element in the Cr-Zr-O structure widens the possibility of its use as an adhesive to attach the veneer to the tooth.

Photoluminescence enhancement of ZrO2:Dy3+ Nanocrystals adding Li+ ions with controlled N2 atmosphere synthetized by coprecipitation method

A series of Dy3+ (0–1 mol%) and Li+ (0.05–1.5 mol%) co-doped zirconium oxide (ZrO2) nanopowders are prepared via coprecipitation, followed by a hydrothermal treatment in nitrogen atmosphere. It was found an optimal concentration of Dy-doped ZrO2 (0.5 mol %) with high emission, showing peaks at 490 nm (blue) and 577 nm (yellow) corresponding to 4F9/2 → 6H15/2, and 4F9/2 → 6H13/2 transitions, respectively with excitation at 350 nm wavelength. Furthermore, the samples of ZrO2:Dy3+ annealing with a controlled N2 showed an increase of 73 and 83% in blue and yellow bands due to decrease of hydroxyl groups (–OH), according to infrared (IR) spectroscopy, which helps to reduce the non-radiative relaxation process. In addition, incorporation Li+ ions up to 0.25 mol% into ZrO2:Dy3+ nanopowders exhibited a further enhancement emission intensity of both bands, owing to this monovalent cation act as coactivator and charge compensator. On the other hand, the color coordinates (x, y) and correlated color temperature (CCT) results suggests that the synthesized nanophosphor can be used as a yellow-orange component for the fabrication of near UV-based w-LEDs.

Effect of Pr doping on structure and luminescence properties of ZrO2 nanoparticles

Pr3+ impurity transitions in monoclinic and cubic phases of ZrO2 have been investigated by photoluminescence and thermoluminescence (TL). Zr(1−x)Pr x O2 (0 ⩽ x ⩽ 0.015) samples were prepared by the combustion method. Rietveld refined x-ray diffraction results confirm that undoped ZrO2 has a monoclinic structure, whereas Pr doped ZrO2 samples are in mixed phase consisting of monoclinic and cubic structures. ZrO2 shows a broad defect-related emission peak centered at 500 nm under an excitation wavelength of 300 nm. A series of Pr3+-related emissions are observed at 512, 584, 612–640 nm due to 3P0 → 3H4, 3P1 + 1I6 → 3H5, 1D2 → 3H4 transitions and between 719 and 740 nm due to 1D2 → 3H5 transitions when excited with 454 nm. The PL decay lifetime of Zr0.996Pr0.004O2 is 1.55 μs for fixed λ ex = 300 nm and λ em = 612 nm. The TL glow curve of Zr0.99Pr0.01O2 shows a prominent peak at 695 K and secondary peaks at 508 K and 570 K, which are not observed in undoped ZrO2. The TL emission measured at 695 K confirms that Pr3+ replaces Zr4+ in cubic lattice sites of ZrO2. This work shows the relationship between the luminescence properties and different structures of ZrO2 and that supports the design of new materials for possible applications.

Sintering behaviour and properties of zirconia ceramics prepared by pressureless sintering

Improvements in the sintering process and powder quality can lead to wider application of zirconia in ceramics. In this study, the effects of different temperatures on the stability, relative content of the tetragonal phase, and composition of Al2O3–ZrO2 ceramic powders were explored using pressureless-assisted sintering. The crystallinity of the sintered Al2O3–ZrO2 samples was significantly improved. The content of the tetragonal-phase ZrO2 in sintered ceramic powders was 52.07%, 52.46%, 56.16%, 63.99%, and 64.90%, respectively, which was significantly higher than those of the raw materials. The average particle size of the sintered samples decreased from 1.07 μm to 0.17 μm with an increase in temperature, indicating that the ceramic powder particles were refined. The sample that was subjected to pressureless-assisted sintering at 1200 °C and held for 1 h exhibited the best stability and more uniform particle distribution compared to other samples. The particle size distribution data were closer to the standard line, satisfying the requirements of the normal distribution law. The results revealed that a high temperature was more favourable to the solid solution, and the formation of an Al2O3–ZrO2 solid solution can diminish the influence of the volume expansion of ceramic powders on the sample properties during sintering. Therefore, the addition of the sintering aid Al2O3 significantly promotes the densification of the powders, and the pressureless sintering technique reduces the sintering temperature of the solid solution, thus imparting a crystalline structure and excellent mechanical properties to the material.

Single-Atom Alloy Pd1Ag10/CeO2–ZrO2 as a Promising Catalyst for Selective Alkyne Hydrogenation

The effect of support on the performance of Pd1Ag10/Al2O3 and Pd1Ag10/CeO2–ZrO2 catalysts in the selective hydrogenation of diphenylacetylene (DPA) was studied. Characterization of the catalyst by DRIFTS-CO and HRTEM revealed the formation of a PdAg single-atom alloy (SAA) structure on the surface of PdAg nanoparticles, with Pd1 sites isolated by Ag atoms. It was found that the use of CeO2–ZrO2 as a carrier makes it possible to increase the activity of the Pd1Ag10 catalyst by a factor of three without loss of selectivity compared to the reference Pd1Ag10/Al2O3. According to the HRTEM data, this catalytic behavior can be explained by an increase in the dispersion of Pd1Ag10/CeO2–ZrO2 compared to its Pd1Ag10/Al2O3 counterpart. As evidenced by DRIFTS-CO data, the high selectivity of the Pd1Ag10/CeO2–ZrO2 sample presumably stems from the stability of the structure of isolated Pd1 sites on the surface of SAA Pd1Ag10/CeO2–ZrO2.

Structural and photoluminescence properties of Dy-doped nanocrystalline ZrO2 for optoelectronics application

Nanocrystalline Dy3+ doped ZrO2 sample has been synthesized using sol-gel wet chemical method. The sample has been investigated for structural, thermal, and photoluminescence properties employing X-ray Diffraction, Fourier Transform Infrared spectroscopy, Thermogravimetric analysis, Transmission Electron Microscopy, UV–visible spectroscopy, and Photo-Luminescence characterization techniques, respectively. The Rietveld refinement of XRD data reveals cubic phase (lattice constant = 5.138 Å) of doped-ZrO2 nano-crystals with space group Fm-3m. The average crystallite size and micro-strain are estimated as 46.21 nm and 0.0047, respectively, from Williamson-hall (W–H) plot analysis. FT-IR spectroscopy confirms the existence of Zr–O vibration modes of ZrO2 phase. The optical band gap of Dy-doped ZrO2 sample is found as 5.3 eV which is analogous to other reports. Photo-Luminescence result shows that the Dy doped-zirconia contains three significant characteristic peaks at 484, 583 and 678 nm under the excitation of a wavelength of 350 nm. Those peaks attribute to the electronic transition of Dy ions. The obtained CIE chromaticity coordinate of doped ZrO2 is (0.337, 0.335) representing neutral white light. The findings of this work implies application of doped zirconia in the area of optoelectronic devices.

Effect of Al2O3 and ZrO2 Filler Material on the Microstructural, Thermal and Dielectric Properties of Borosilicate Glass-Ceramics

Various glass-ceramics are widely used or considered for use as components of microelectronic materials due to their promising properties. In this study, borosilicate glass was prepared using the powder metallurgical route and then mixed with different amounts of Al2O3 and ZrO2 filler materials. Glass-ceramics are produced by high-energy ball milling and conventional sintering process under Ar or air. In this study, the effects of different filler materials and different atmospheres on the microstructural, thermal and dielectric properties were investigated. The data showed that ZrO2 filler material led to better results than Al2O3 under identical working conditions and similar composite structures. ZrO2 filler material significantly enhanced the densification process of glass-ceramics (100% relative density) and led to a thermal conductivity of 2.904 W/K.m, a dielectric constant of 3.97 (at 5 MHz) and a dielectric loss of 0.0340 (at 5 MHz) for the glass with 30 wt.% ZrO2 sample. This paper suggests that prepared borosilicate glass-ceramics have strong sinterability, high thermal conductivity, and low dielectric constants, making them promising candidates for microelectronic devices.

Subthreshold Laser Ablation Measurements by Langmuir Probe Method for ns Irradiation of HfO2 and ZrO2.

The unbiased Langmuir probe (LP) method was used to perform measurements on HfO2 and ZrO2 samples around the laser ablation threshold on a wide range of irradiation conditions. Important changes in the lifetime (from ms to μs) and the shape of the charge particle current were seen with the increase of the laser fluence. The ablation threshold was estimated by evaluating the overall average ablated charge as a function of the laser fluence. Above the ablation threshold, the generation of high kinetic species is seen, which can reach several keV. An important jump in ion acceleration potential is observed for values above 1 J/cm2, which coincides with the dominant presence of negative ions in the plasma. The evolution of several plasma parameters (ion density, expansion velocity, electron temperature, Debye length) was investigated and correlated with the fundamental ablation mechanism involved in various irradiation regimes. The LP data were correlated with COMSOL simulations on the maximum surface temperature reached during irradiation. Important correlations between the evaporation and melting processes and ablation threshold fluence and ion acceleration phenomena are also reported.