Zr Content Research Articles

Titanite as an indicator of granite fertility and gold mineralization in the Xiaoqinling gold province, North China Craton

The Xiaoqinling gold province, located in the southern margin of the North China Craton (NCC), is the second largest gold-enriched region in China. In this region, the Mesozoic Huashan (HS) and Wenyu (WY) plutons are the major magmatic intrusions coeval with gold mineralization, although they show contrasting characteristics in the distribution of gold. In this study, we use geochemical features of titanite determined by LA-ICP-MS and EPMA analyses and elemental mapping to decipher the mechanisms that led to the difference in gold enrichment related to the two plutons. Titanite from the Wenyu granitic pluton exhibits significantly higher (La/Sm)N, (La/Yb)N, ΣLREE/ΣHREE ratios, and ΣREE concentration and slightly higher (Gd/Yb)N values than those of the Huashan Pluton, suggesting that the Wenyu pluton might have experienced more complex magmatic evolution, widespread hydrothermal alteration, and higher silica activity in the melt than the Huashan pluton. The titanite grains from the Huashan pluton show higher (Nb/Ta)N and (Lu/Hf)N values and significantly lower Zr concentration than those of the Wenyu pluton. The titanite grains from the Wenyu pluton show higher vanadium and gallium concentrations and Fe/Al ratio than those of the Huashan pluton, indicating comparatively higher fo2. Furthermore, the titanite grains from Wenyu pluton indicate higher water content in the magma. In addition, magma mingling and magmatic hydrothermal fluids derived from the crust/mantle are critical sources for ore-forming materials. These results suggest that the Wenyu pluton is more conducive to gold migration and enrichment than the Huashan pluton.

Enhanced energy storage performance inBaZrxTi1-xO3 lead-free ferroelectrics near phase transitions.

The present study explores the energy storage properties of BaZrxTi1-xO3 through phase-field modeling, focusing on the impact of composition and temperature on energy storage performance. The obtained results reveal a variety of polarization phases and configurations based on Zr compositions and temperatures. A detailed phase diagram for temperature-composition of BaZrxTi1-xO3 is established, closely aligning with experimental measurements. Variations in Zr content and temperature have a significant impact on the polarization-electric field response, influencing the energy storage properties. Calculations of energy storage properties are derived from the polarization-electric field response. In addition, a thorough diagram is developed to illustrate the discharge energy density of BaZrxTi1-xO3 as a function of temperature and composition. Notably, high discharge energy density is achievable near the Curie temperature, corresponding to the transition from ferroelectric to paraelectric phase. Furthermore, the present study emphasizes the importance of the disparity between maximum and remanent polarization, as well as the electric field-dependent effective permittivity, in determining the discharge energy density.&#xD.

Elaboration and Characterization of Different Zirconium Modified ETS Photocatalysts for the Degradation of Crystal Violet and Methylene Blue.

In this study, Zirconium-modified Engelhard Titanium Silicate 4 (Na-K-ETS-4/xZr) catalysts were synthesized and evaluated for their photocatalytic efficiency in degrading crystal violet (CV) and methylene blue (MB) in aqueous solutions. The catalysts were characterized using XRD, FTIR, SEM, WDXRF, and nitrogen adsorption/desorption isotherms. The results confirmed the successful incorporation of Zr into the ETS-4 framework, with the highest Zr content reaching 9.2 wt %. The photocatalytic performance under visible light irradiation was studied at varying pH levels. The Na-K-ETS-4/6.3Zr catalyst exhibited the highest photodegradation efficiency for CV (76.6 %), while Na-K-ETS-4/8.9Zr achieved 86.6 % efficiency for MB. A combination of Engelhard Titanium Silicate 10, Na-K-ETS-10/6.3Zr and Na-K-ETS-4/8.9Zr significantly enhanced dye degradation, achieving up to 96.5 % efficiency for MB. Kinetic studies indicated that the degradation process follows a non-linear pseudo-first-order model. The catalysts also demonstrated excellent reusability, with minimal efficiency loss after five cycles, and full recovery after an ethanol wash. These findings suggest that Na-K-ETS-4/xZr is a promising candidate for environmental water treatment applications due to its efficient photodegradation performance and stability.

Fluorous and Organic Extraction Systems: A Comparison from the Perspectives of Coordination Structures, Interfaces, and Bulk Extraction Phases.

Microscopic structures in liquid-liquid extraction, such as structuration between extractants or extracted complexes in bulk organic phases and at interfaces, can influence macroscopic phenomena, such as the distribution behavior of solutes, including extraction efficiency and selectivity. In this study, we correlated the macroscopic behavior of the Zr(IV) extraction from nitric acid solutions with microscopic structural information to understand at the molecular level the key factors contributing to the higher metal ion extraction performance in the fluorous extraction system as compared to the analogous organic extraction system. The fluorous and organic extraction systems consist of tris(4,4,5,5,6,6,7,7,7-nonafluoroheptyl) phosphate (TFP) in perfluorohexane and tri-n-heptyl phosphate (THP) in n-hexane, respectively. Extended X-ray absorption fine structure, neutron reflectometry (NR), and small-angle neutron scattering revealed the structural information around the central metal ion of the complex, at the interface, and in the bulk extraction phase, respectively. NR results showed that extractant molecules did not accumulate much at the interface in both extraction system. In the fluorous extraction system, extractant aggregates with a 1.46 nm radius of gyration (Rg) were formed after contact with nitric acid, and remained even after Zr(IV) extraction through the form of a 1:3 (Zr(IV):TFP) complex. In contrast, in the organic extraction system, only extractant dimers with Rg of 0.70 nm were formed and Zr(IV) is extracted through the form of a 1:2 (Zr(IV):THP) complex. We speculate that differences in the local coordination structure around the Zr(IV) ion and the structuration of the extractant molecules in the bulk extraction phase contribute to the high Zr(IV) extraction performance in the fluorous extraction system. In particular, the size of the aggregates hardly changed with increasing Zr(IV) concentration in the fluorous phase, which may be closely related to the absence of phase splitting in the fluorous extraction system.

Widespread ca. 800 Ma granitoids in the southern Dabie Orogen: Petrogenesis and implications for Neoproterozoic accretion-type orogeny in the northern Yangtze Block

Large-scale Neoproterozoic granitoids occur widely in the Dabie Orogen of the northern Yangtze Block and provide significant clues to understanding the geological evolution of the Block within the Rodinia supercontinent. We present evidence for a prominent episode of granitoid intrusion at ca. 800 Ma in the southern Dabie Orogen (SDO), verified by new zircon LA-ICP-MS ages from four separate granitoid intrusions ranging from 807 Ma to 795 Ma in age. The granitoids are dominated by monzogranite and granodiorite with bulk-rock A/CNK and zircon δ18O values of 0.90–1.10 and 5.03–6.45‰, respectively, corresponding to I-type affinity. This is also supported by negative correlations of SiO2 vs. P2O5 and Sr vs. P2O5, and positive correlations of SiO2 vs. A/CNK, Rb vs. Y and Rb vs. Th. Low zircon εHf(t) values (−15.03 to −3.84) and relatively old two-stage Hf model ages (mainly between 1900 and 2200 Ma) for these granitoids are consistent with primary derivation of magma from partial melting of Paleoproterozoic metabasites. Relatively low Ga/Al ratios, Zr contents, and zircon saturation temperatures and consistently negative zircon εHf(t) and bulk-rock εNd(t) values are distinct from those of 780–720 Ma A-type granites in the Dabie Orogen that formed in a rift setting. We propose that the ca. 800 Ma granitoids in the SDO were products of variable degrees of partial melting of ancient mafic crust, promoted by heating of the upwelled asthenosphere due to oceanic slab breakoff in an accretion-type orogeny. Our observations suggest that the formation of the unified Yangtze Block was achieved by diachronous assembly of multiple micro-blocks during the Neoproterozoic, consistent with a peripheral location of the Yangtze Block in the Rodinia supercontinent.

Tuning CO2 Hydrogenation to Light Olefin Selectivity via Cu/Zn/Zr Supported on Modified SAPO‐34

AbstractTo alleviate CO2 emissions and reduce reliance on fossil fuels, a groundbreaking bifunctional catalyst system was introduced, which ingeniously merged CZZ with modified SAPO‐34 zeolite, to convert CO2 into light olefins. Different metals were impregnated into SAPO‐34 to form MeSAPO‐34 (Me = Zn, Zr, Mn) and the metal Zr content was altered. Furthermore, CZZ and MeSAPO‐34 was combined into CZZ/MeSAPO‐34 composite catalysts, which was used for CO2 hydrogenation. The MeSAPO‐34 and xZrSAPO‐34 catalysts were rigorously characterized by various techniques, revealing key physicochemical attributes. This innovative approach harnessed the synergistic effects between the metallic CZZ component and the modified zeolite to facilitate a series of reactions, effectively generating C2‐C4‐rich hydrocarbons. Benefiting from weak acid, higher oxygen vacancy concentration and interactions between components, the CZZ/ZrSAPO‐34 catalyst system has shown remarkable efficiency in enhancing the light olefin selectivity. The key aspects of this system are its ability to modulate surface acidity and oxygen vacancy concentration, thus creating favorable conditions for light olefin production via enhanced tandem reaction based on CO2 hydrogenation. This work enriches our insight into designing novel composite catalysts for promoting CO2 conversion and hence mitigating CO2 emissions.

Corrosion studies of Al-Mg-Sc-Zr Alloy with Low Sc/Zr ratio fabricated by laser powder bed fusion for marine environments

This study investigates the corrosion behavior of a laser powder bed fusion (LPBF) Al-Mg-Sc-Zr alloy with a Sc/Zr ratio of less than 1 in 3.5wt% NaCl solution. X-ray diffraction (XRD) analysis revealed the presence of an Al matrix with face-centered cubic (FCC) structure and the secondary phase Al3(Sc,Zr) with L12 crystal structure. Microstructural analysis indicated a bimodal grain size distribution with fine equiaxed and columnar grains influenced by thermal gradients and secondary phase Al3(Sc,Zr). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in 3.5wt% NaCl solution demonstrated that the alloy exhibits a less negative corrosion potential (Ecorr) and lower corrosion current density (icorr) compared to other Al-Mg-Sc-Zr alloys with higher Sc/Zr ratios, indicating superior corrosion resistance. The enhanced performance is attributed to the fine grain structure and the formation of a stable protective oxide layer facilitated by the higher Zr content.

Molecular dynamics simulation of gradient alloying distribution on the nano-mechanical properties of Nb-Zr alloys

Abstract In this work, a nano-indentation process of homogeneous Nb-Zr alloy and gradient Nb-Zr alloy was simulated using molecular dynamics simulation. The effects of Zr content, system temperature, indentation radius on the mechanical properties and micro-deformation were investigated. Comparing the homogeneous and gradient alloys, it was revealed that the gradient alloy had a smoother mechanical performance. The results showed that the effect of Zr content on the hardness of Nb-Zr homogeneous alloy was not linear. The hardness rose followed by a decline with increasing Zr content and the turning point came at 1.5 wt.%. Under high temperatures, the Nb-Zr homogeneous alloy and gradient alloy layer retained extremely high hardness, exhibiting excellent mechanical properties. Due to the entanglement of multiple dislocations in gradient Nb-Zr alloy at high temperatures, the hardness still increased with increasing temperature at high temperatures. The influence of indentation size on nano-indentation experiments was mainly affected by the curvature of the indented part. It was worth noting that gradient alloys could disperse stress faster and reach a stable state during the loading process. The hardness of the Nb-Zr homogeneous alloy layer first increased and then decreased as the Zr content changed from 1.0 wt.% to 2.0 wt.%, as verified by the experiments. This study provided the reference for the preparation of high-temperature applications alloy by constructing Nb-Zr gradient alloy.

Preparation of a novel high-entropy alloy AlNbTiVZr with excellent strength and ductility: The effect of Zr composition on microstructure and properties

Light-weight refractory high-entropy alloys with low density and good ductility are widely used in various engineering fields. Despite their potential, achieving an optimal strength-ductility balance in these lightweight alloys remains an emerging field of study. In this study, Al0.8Nb0.5Ti2V2Zrx (x = 0, 0.3, 0.6, and 0.9) alloys were prepared by vacuum arc melting. A comprehensive evaluation of their microstructure, density, hardness, and compressive behavior at both room and 873 K temperatures was conducted. The introduction of Zr transforms the alloy phase structure from body-centered cubic (BCC) to BCC + C14-Laves. The areal fraction of the C14-Laves phase increased from 0 % to 32.47 % with increasing Zr content from x = 0 to 0.9, respectively. Furthermore, the Zr content had an obvious effect on the mechanical properties of the alloys. The compressive strength and hardness of the alloys improved, but the ductility simultaneously decreased, with increasing Zr content. The yield strengths of the alloys with x = 0, 0.3, 0.6, and 0.9 reached 971, 1216, 1483, and 1714 MPa, respectively, at room temperature, and 946, 1287, 1319, and 1469 MPa, respectively, at 873 K. In addition, the alloys maintained their deformation resistance and good ductility at 873 K. In particular, the Al0.8Nb0.5Ti2V2Zr0.3 exhibited a good balance between strength and ductility at room and 873 K temperatures due to the strengthening effect of a granular secondary phase. Upon comparison with other reported high-entropy alloys, the Al0.8Nb0.5Ti2V2Zrx series showcased superior specific yield strength and ductility.

Structural, Electronic, and Mechanical Properties of α(U) and α(U-Zr) Alloy Fuels

Uranium-zirconium (U-Zr) alloy fuels have been taken into consideration for fast reactors because of their superior reactor safety, high uranium (U) density, and excellent thermal conductivity. In this paper, the structural and mechanical properties of metallic U and U-Zr alloy fuels are calculated at the atomic level by density functional theory–based calculations with Hubbard U (density functional theory + U) corrections. Several structure-property relations, such as lattice volume, bulk modulus, Young’s modulus, shear modulus, electronic density of states, etc. are calculated for U metal and U-Zr alloy fuels. In addition, the Zr content in metallic U fuel is adjusted from roughly 5 at. % to 15 at. % in order to determine how the Zr content affects the characteristics of U-Zr fuel material. A linear relationship between the volume and Zr concentrations is observed. The concentration of Zr in the fuel affects the mechanical characteristics of U-Zr alloy fuel. It is also observed that the electronic structure of the α-U phase is not changed significantly in the presence of Zr. Our computations provide insight into how U-Zr alloy fuels behave in reactor conditions.

Theoretical Insights into Off-Stoichiometric Zr(x)Ti(1-x)IrSb Half-Heusler Alloys: A First Principle Calculations.

This study presents a theoretical investigation into the phase stability, electronic, and optical properties of off-stoichiometric Zr_{x}Ti_{1-x}IrSb (x = 0, 0.0625, 0.1875, 0.25, 0.50, 0.75, 1) compounds. Using first-principles calculations, we explore how varying Zr and Ti concentrations can tune the electronic and optical properties of these half-Heusler alloys. The Structural, optical, and electronic properties were meticulously analyzed with both the GGA-PBE and Meta-GGA-SCAN approximations, as implemented in the Vienna Ab initio Simulation Package (VASP). The dynamical stability of these compounds was assessed using the Phonopy package. Our findings reveal that these alloys exhibit semiconductor behavior with tunable band gaps, and their optical properties show significant variation across different compositions, particularly in the visible light range. The compounds also demonstrate robust dynamical stability, indicating their potential for practical applications in electronic and optoelectronic devices. These results underscore the versatility of Zr_{x}Ti_{1-x}IrSb alloys and highlight their promise for next-generation technology.

Comparison of 35 trace elements content in malignant breast tumors with their content in the normal female mammary gland: Original data and a mini-review

Objective: In many countries, including Russia, breast cancer ranks first in the incidence of cancers in women. The etiology of this disease remains largely unclear, but there is evidence indicating that disturbances in the somatic homeostasis of trace elements may be involved in the process of oncogenesis. Therefore, this study was aimed at identifying changes in the content of trace elements during malignant transformation of breast tissue.Methods: For this purpose, an effective method of small sample analysis by means of inductively coupled plasma mass spectrometry was developed. The method makes it possible to determine the content of 35 trace elements in microsamples (with mass ≥ 10 mg) of breast tissue obtained by puncture biopsy. With the help of this technique, the samples of cancerous (n = 43) and normal (n = 38) breast tissue were studied.Results: In malignant breast tissue, the content of Al, As, B, Cd, Co, Cs, Cu, Mg, Mn, Mo, Ni, Rb, Se, Sr, Ti, Tl, U, V, Zn, and Zr was higher, while the content of Ge, Pb, Sb and Th was lower than in healthy gland tissue. All the identified differences were statistically significant.Conclusions: The significant disruption of somatic homeostasis of trace elements resulting from malignant transformation of breast tissue has been described, but its cause has not been determined, so additional research is required. Further the method we employ, which we have developed and described here, requires tissue samples weighing only a few milligrams, so it is possible to use it with tissue obtained from puncture tissue biopsies.

Study on Ni3Al-Based Single Crystal Superalloy Joints Brazed by Vacuum Brazing with Zr-Containing Filler

Melting point depressants (MPDs) are required to lower the melting point of filler for brazing. In this study, Zr was used as the MPD, and powder filler was prepared by adjusting the Zr and Mo content referring to Thermo-Calc calculations. The prepared filler was used to braze a high-Mo Ni3Al-based single crystal superalloy, IC21, for 1200 °C/30 min. The effects of adjusting the Zr and Mo content on the microstructure and tensile properties of the joint were investigated. The increase in Zr content promotes the formation of Ni7Zr2 in the joint, leading to a decrease in the tensile strength of the joint. The increase in Mo content forms diffusion barriers between the BM and filler, resulting in an enhancement in the tensile strength of the joint. However, continued increases in Mo content leads to an increase in the P-topologically close packed phase, causing a decline in the tensile strength of the joint. When the Zr content was (11.8–12.2) wt.% and the Mo content was (7.3–7.7) wt.%, the tensile strength of the joint at 980 °C reached a maximum of 550 MPa. This study provides a potential direction for the design of brazing filler composition for high-Mo Ni3Al-based superalloys.

Evolution of ferroelectric and piezoelectric properties of BiFeO3 ceramics doped with lanthanum and zirconium

In this study, we performed cation substitutions at Bi-site (La3+) and Fe-site (Zr4+) to investigate their possible benefit for the ferroelectric properties of BiFeO3 ceramics. The cations with higher valence (Zr4+) ought to suppress the formation of structural defects during syntheses, such as oxygen vacancies and Fe2+. These defects are responsible for high leakage currents and low breakdown voltages characteristic of the pure BiFeO3. However, doping only with Zr did not improve the ferroelectric properties of bismuth ferrite. These samples were unable to persist electric fields above 30 kV/cm. On the other hand, the increase in lanthanum concentration resulted in improved ferroelectric and piezoelectric properties of the samples, sustaining electric fields above 100 kV/cm. Among the investigated samples, the highest remnant polarization of 24 μC/cm2 and piezoelectric coefficient (d33) of 34 pC/N reached Bi0.85La0.15FeO3 sample at 160 kV/cm. The share of non-ferroelectric contribution to the total polarization of this sample was the lowest (∼ 11 %). When it comes to the co-doped samples, the addition of Zr transformed the behavior from leaky ferroelectric to predominantly leaky dielectric. It indicated that doping with La significantly improved the ferroelectric properties of bismuth ferrite ceramics. In contrast, even a low Zr concentration of 1 mol% could outbalance the influence of much larger La concentrations (10 and 15 mol%).

Molecular dynamics study on the deformation mechanism of Cu–Zr/Al laminated composites

In this paper, molecular dynamics simulation was used to investigate the micromechanical behavior of the Cu–Zr/Al composite interface after rapid solidification. The effects of different Zr contents and different strain rates on the tensile strength of the Cu–Zr/Al composite interface were investigated. The results show that the tensile strength of the composite plate increased and then decreased with the increase of Zr content, and the tensile strength is the highest when the Zr content is 0.33 wt%. It was found that the plastic deformation process of the composite model at different strain rates is similar, which is divided into three stages: the expansion of stacking faults in the Cu–Zr/Al solid solution, the expansion of stacking faults successively in the Al and Cu–Zr alloy layers, and the spreading of cross - stacking faults. But the greater the strain rate is, the slower the stacking faults fracture is. So the composite model with different strain rates had different fracture modes during the tensile fracture process. When the strain rate is 0.01 ps−1 and 0.001 ps−1, it is a ductile fracture, while when the strain rate is 0.0001 ps−1, it is a brittle fracture.

Effect of Zr addition on MnS inclusion characteristics and mechanical properties in medium carbon ferrite-pearlite steel

In this paper, the influence of decreasing Zr content (0.0110wt%, 0.0044wt%) on the microstructure, MnS inclusion characteristics, and mechanical properties of medium carbon ferrite-pearlite steel was studied. The results show that the volume fraction of intragranular ferrite (IGF) in steel increases with a reduction in Zr content. The ductility of the steel is reduced by 1.83%, the impact toughness is increased by 2.5 times, and the yield strength is almost unchanged. Compound MnS inclusions are the main inclusions that induce IGF formation. The proportion of heterogeneous nucleation of MnS inclusions using oxides as nucleation sites is increased, which is the main reason for the increase in the volume fraction of IGF. Furthermore, MnS inclusions change from type Ⅲ to type Ⅰ and Ⅱ, and their distribution is gradually uniform. Thermodynamic analysis reveals that the underlying cause for the morphological transformation of MnS inclusions is the rapid surge in the supersaturation of S element in molten steel. The presence of liquid-phase low-melting inclusions (MnS-Al2O3) promotes the formation of type Ⅰ MnS inclusions. The volume fraction and the dimension perpendicular to the fracture surface of the MnS inclusions are increased by at least 33% and 111%, while their aspect ratio is reduced by a maximum of up to 19%. The change in the volume fraction of MnS inclusions is the primary factor contributing to the decrease of tensile plasticity. The toughness of steel is mainly affected by the aspect ratio and the dimension perpendicular to the fracture surface of MnS inclusions.

The elemental variance between the "rice" and "non-rice" portions of Maifanitum and its health risk assessment

BackgroundMaifanitum, a mineral used in Chinese medicine, was first documented during the Song Dynasty (960-1279). Historical records suggest its multifaceted therapeutic properties, including detoxification and stasis resolution, necrosis removal and tissue regeneration, diuretic and calculi dissolution and prolonging life. The concentration of elements in Maifanitum may vary depending on its origin, different parts, which can affect its effectiveness in different fields of applications. Therefore, the analysis of elements in Maifanitum and the subsequent health risk assessment have been conducted. This provides an important basis for the quality control and application safety of Maifanitum. MethodThe analytical techniques employed in this study are inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES), utilized for the quantitative assessment of 60 elements (Refer to Appendix 1) within Maifanitum samples. Based on the test results, chemometric methods are employed to evaluate the characteristics and differences in elemental concentration from different sources and locations. Additionally, a preliminary health risk assessment is conducted for Maifanitum from different origins and various parts. ResultsWe have established a fingerprint of the elements within Maifanitum, demonstrating a commendable level of similarity. The findings from hierarchical cluster analysis（HCA） corroborated with those from principal component analysis (PCA), collectively unveiling a systematic profile of elemental disparities between Maifanitum samples of diverse origins and applications. It also revealed that there are differences in the concentration of Al, Ga, Be, Hf, Na, Sn, Ti, Zr, Gd, Tb, Sr, Pb, Ce, Ba and other elements in different parts of Maifanitum. While Cd, As, and Cu levels in all samples were within the permissible limits as defined by the Chinese Pharmacopeia, Pb concentrations in the majority of samples were found to surpass these standards, albeit slightly in the ''non-rice'' fraction. The assessment of both beneficial and deleterious elements indicates that the ''non-rice'' fraction of Maifanitum possesses superior quality attributes. Moreover, the overall concentration of rare earth elements in Maifanitum is substantially below the established lower threshold for daily human consumption, with no immediate evidence suggesting any adverse health risks. ConclusionThis study provides a basis for the quality control and safety evaluation of Maifanitum in clinical use.

Effect of Zr content on microstructure and wear behavior of Al-Si-Cu-Ni Mg-Zrx alloy

Effect of Zr content on microstructure and wear behavior of Al-Si-Cu-Ni Mg-Zrx alloy

Bio-based nylon intermediates from γ-valerolactone: Catalyst modifications for an enhanced selectivity to methyl 4-pentenoate

Ring-opening transesterification of bio-based γ-valerolactone (GVL) to produce a mixture of methyl pentenoate isomers (MPs) such as methyl 4-pentenoate (M4P), methyl 3-pentenoate (M3P) and methyl 2-pentenoate (M2P) has been carried out using modified Zr-containing catalysts in a gas phase continuous process. As the three MP isomers are potential nylon intermediates, this approach is sustainable from a green chemistry point of view to synthesize bio-based polymers. The reaction was carried out in a fixed bed catalytic reactor at ambient pressure and in the temperature range from 255 to 335°C. In the present study, SiO2 supported zirconia catalysts were prepared by wet impregnation with varying Zr loadings in the range from 5 to 30wt%. The catalysts were characterized by various techniques. The surface areas were determined by N2 adsorption, acid-base properties by NH3-TPD and CO2-TPD techniques. In addition, the distinction of Lewis and Brønsted sites were also estimated by Py-FTIR. Among all catalysts, 25% Zr/SiO2 exhibited the best performance. The influence of various key reaction parameters on the activity/selectivity was explored and suitable reaction conditions were optimized. The conversion of GVL and product distribution was found to be strongly dependent on the reaction temperature and Zr content of the catalysts. The sum selectivity of all the three MP isomers varied in the range from 97 to 99%, of which M4P was always the dominant product. At low reaction temperature (255°C), M4P was the major product while M2P was a minor product. However, with increase in temperature, the selectivity of M2P and M3P increased at the expense of M4P due to isomerisation of the C=C double bond. In addition, the effect of support on the best Zr loading was also explored and it was found that the SiO2 support exhibited superior performance compared to others. In the direction of enhancing the selectivity of M4P, Cr-doping was also done onto 25Zr/SiO2, the best catalyst of this study. Such incorporation of chromium significantly enhanced the selectivity of M4P above 80% at acceptably high conversion of GVL.

Enhancement of dielectric constant in Sm:Zr co-doped HfO2 films synthesized by cost-effective method

Sm, Zr co-doped HfO2 films were deposited on a p-type silicon wafer using a cost-effective spin coating method. The influence of Sm, Zr co-doping concentration variation on structural, compositional, morphological, and electrical properties was examined. The dominance of the orthorhombic phase (o-phase) in comparison to the monoclinic phase was noted to rise with the simultaneous increment of Sm doping concentration and decrement of Zr concentration. A decrease in oxygen vacancies was noted for all the Sm, Zr co-doped HfO2 films from XPS results. Nonporous and uniform distribution of grains was observed from Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM) studies. Electrical studies of MOS capacitors based on Sm, Zr co-doped HfO2 films revealed a low leakage current. C-V studies exhibited an increment of dielectric constant and a decrement of interface trap densities. Further, to obtain insights into the microscopic features of Sm, Zr co-doped films, impedance and modulus studies have been performed. The obtained results imply the potential of tuning Sm, Zr co-doping concentrations in HfO2 towards stabilization of the orthorhombic phase and to enhance the dielectric constant of the films.