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The sol–gel process is a green method used in the last few decades to synthesize new organic–inorganic phosphorus-containing hybrid materials. The sol–gel synthesis is a green method because it takes place in mild conditions, mostly by using water or alcohol as solvents, at room temperature. Therefore, the sol–gel method is, among others, a promising route for obtaining metal-phosphonate networks. In addition to phosphorus, the obtained hybrid materials could also contain titanium, zirconium, boron, and other elements, which influence their properties. The sol–gel process has two steps: first, the sol formation, and second, the transition to the gel phase. In other words, the sol–gel process converts the precursors into a colloidal solution (sol), followed by obtaining a network (gel). By using the sol–gel method, different organic moieties could be introduced into an inorganic matrix, resulting in organic–inorganic hybrid structures (sometimes they are also referred as organic–inorganic copolymers).

Bioactive glass is one interesting type of material for bone repair. In this work, a new powder (MBG2) was synthesized by a sol–gel method, in which 5 mol.% Mg and 5 mol.% Zr were incorporated into the structure, to investigate the combined effects of the simultaneous addition of these ions on the biological properties of 45S5 mesoporous bioactive glass. Then, the outcomes of various characterization techniques and in vitro biological analyses performed on this powder were compared with those of pure powder (MBG1). For instance, the XRF investigation proved that Zr and Mg ions were present in powder MBG2′s composition. Additionally, XRD, SEM, and BET tests of the powders MBG1 and MBG2 indicated their amorphous structure and spherical morphology with specific surface areas of 620 and 710 m2/g and average particle sizes of about 30 and 20 nm, respectively. The development of an apatite layer on the surfaces of disc-shaped samples produced from both powders were immersed in phosphate-buffered saline (PBS) and simulated body fluids (SBF), and the behavior of the samples' degradation were observed for 28 days. Furthermore, it was assessed how the Zr and Mg ions in the composition affected the MG-63 cells' survival, growth, and adhesion through in vitro biocompatibility testing. From the obtained results, it can be concluded that 45S5 mesoporous bioactive glass powder with minimal cytotoxicity was entitled to be a safe biomaterial due to the coexistence of 5 mol.% Mg and 5 mol.% Zr in the composition, which successfully enhanced bioactivity, cell proliferation, and biocompatibility.

Zr/Hf separation has always been a great challenge. Although the methyl isobutyl ketone (MIBK)-thiocyanic acid (HSCN) extraction system selectively extracts Hf over Zr and can realize Zr/Hf separation, it has the following disadvantages: it has a strong smell; it is easy to burn; and there is large loss of extractant during extraction due to the low boiling point (115.7 °C), low flashing point (13 °C), and high solubility of MIBK in water (1.7 % at 25 °C). In this study, Zr/Hf separation performance by MIBK homologues — of which one side of C = O is isopentyl, isohexyl, n-pentyl, n-hexyl or n-heptyl, while the other side are all methyl — were studied and compared with MIBK. Effects of HSCN pre-extraction, HCl concentration, NH4SCN concentration on Zr, Hf extraction and separation performance were investigated. Relationships between methyl alkyl ketone structure and their Zr/Hf separation performance were revealed. A new Zr/Hf separation system MNPK (methyl n-pentyl ketone)-HSCN was found. MNPK has a higher boiling point (151 °C), a higher flashing point (47 °C) and a lower solubility in water (0.43 % at 20 °C) than MIBK. Compared to MIBK, it is safer, more friendly operation environments and less extractant loss during extraction. MNPK has as fast extraction kinetics as MIBK. It also has good anti-emulsification performance. Its maximum βHf/Zr can reach to 12.61. The loaded Zr and Hf in MNPK have very similar stripping behaviors with those loaded in MIBK by HCl and H2SO4 solutions, respectively. MNPK is the most possible candidate to replace MIBK from HSCN media in Zr/Hf separation industry.

The extraction of zirconium (Zr) and hafnium (Hf) in methyl isobutyl ketone (MIBK)—thiocyanic acid (HSCN) system has been widely used in the production of nuclear-grade zirconium and hafnium in industry, while the extraction mechanism was not adequately studied. In this study, the extraction and stripping equilibrium of Zr and Hf in the MIBK-HSCN system was studied. The results showed that elevated HCl concentration can increase the distribution ratio of SCN− and decrease that of Zr/Hf in organic phase. In the stripping process, HCl concentration and the Organic/Aqueous (O/A) phase ratio played important roles. The mechanism of the extraction reaction was discussed by considering the stoichiometric relationship of possible reaction equations and corresponding equilibrium constants. The results indicated that SCN− could be extracted into MIBK as HSCN·MIBK. Meanwhile, SCN− could also be extracted into MIBK by complexing with metal (Zr or Hf). The molar ratios of MIBK to the complexes of Zr and Hf have been found to be 5.34 and 5.03, respectively. With the increase in the initial concentration of HCl in the aqueous phase, the complexation molar ratios of SCN− to Zr and Hf increased first and then decreased, and so do the extraction equilibrium constants, which might be due to the extraction competition of HSCN and metal complexes.

Although Zr-based metal–organic frameworks (MOFs) exhibit robust chemical and physical stability in the presence of moisture and acidic conditions, their susceptibility to nucleophilic attacks from bases poses a critical challenge to their overall stability. Herein, we systematically investigate the stability of Zr-based UiO-66 (UiO = University of Oslo) MOFs in basic solutions. The impact of 11 standard bases, including inorganic salts and organic bases, on the stability of these MOFs is examined. The destruction of the framework is confirmed through powder X-ray diffraction (PXRD) patterns, and the monitored dissolution of ligands from the framework is assessed using nuclear magnetic resonance (NMR) spectroscopy. Our key findings reveal a direct correlation between the strength and concentration of the base and the destruction of the MOFs. The summarized data provide valuable insights that can guide the practical application of Zr-based UiO-66 MOFs under basic conditions, offering essential information for their optimal utilization in various settings.

The efficient separation of Zr(IV) ions from strong acidic and radioactive solutions is a significant challenge, especially in the context of the aqueous reprocessing of nuclear fuels. The complexity of such solutions, which are often characterized by high acidity and the presence of radioactive elements, poses formidable challenges for separation processes. Herein, several mesoporous silicas (HMS, MCM-41, KIT-6, and SiO2-70 Å) with excellent acid and radiation resistance properties were employed as sorbents to remove Zr(IV) ions from simulated high-level liquid waste. The batch experiments were designed to investigate the influence of adsorption time, HNO3 concentration, initial Zr(IV) concentration, adsorbent dosage, and temperature on the adsorption behavior of Zr(IV). The results indicate that the adsorption equilibrium time of mesoporous silica materials was approximately 8 h, and all the adsorption processes followed the pseudo-second-order kinetics equation. The isotherms of Zr(IV) adsorption by KIT-6 exhibited good agreement with the Langmuir model, while the Freundlich model could be utilized to fit the adsorption on HMS, MCM-41, and SiO2-70 Å. The adsorption capacity of MCM-41 for Zr(IV) in 3 mol/L HNO3 was 54.91 mg/g, which is three times the adsorption capacity reported for commercial silica gel (17.91 mg/g). The thermodynamic parameters indicate that the adsorption processes for zirconium are endothermic reactions. Furthermore, the mesoporous silicas exhibited a pronounced selectivity in the adsorption of Zr(IV) within a simulated high-level liquid waste containing 10 co-existing cations (3 mol/L HNO3). This suggests that mesoporous silicas have great potential for Zr(IV) removal in actual radioactive liquids with high acidity during spent fuel reprocessing.

The SEM-EDX method was used to investigate the structure and morphology of organic–inorganic hybrids containing zirconium, boron and phosphorus compounds, synthesized by the sol–gel method. We started by using, for the first time together, zirconyl chloride hexa-hydrate (ZrOCl2·6H2O), phenyl phosphinic acid and triethyl borate as precursors and reagents, at different molar ratios. The obtained hybrids showed a very high thermal stability and are not soluble in water or in organic solvents. As a consequence, such hybrid solid materials are suitable for applications at high temperatures. The obtained hybrids have complex 3D structures and form organic–inorganic networks containing Zr-O-Zr, Zr-O-P and Zr-O-B bridges. Such organic–inorganic networks are also expected to form supramolecular structures and to have many potential applications in different fields of great interest such as catalysis, medicine, agriculture, energy storage, fuel cells, sensors, electrochemical devices and supramolecular chemistry.

In this study, new mono- and di-alkoxido zirconium(IV) complexes supported by tetradentate dianionic cyclam ligands were synthesized and characterized. These compounds were obtained by reaction of the parent Zr(IV) dichlorido species with one or two equivalents of the corresponding lithium alkoxido, whereas (3,5-Me2Bn2Cyclam)Zr(OPh)2 was prepared by protonolysis of the orthometallated species (3,5-Me-C6H4CH2)2Cyclam)Zr with phenol. The solid-state molecular structures of (Bn2Cyclam)ZrCl(OtBu) and (4-tBuBn2Cyclam)Zr(OiPr)2 show a trigonal prismatic geometry around the metal centers. (Bn2Cyclam)Zr(SPh)(OtBu) and (Bn2Cyclam)ZrMe(OiPr) were prepared by reaction of (Bn2Cyclam)ZrCl(OR) (R = iPr, tBu) with one equivalent of LiSPh or MeMgCl, respectively. The reactions of (Bn2Cyclam)Zr(OiPr)2 and (4-tBuBn2Cyclam)Zr(OiPr)2 with carbon dioxide suggested the formation of species that correspond to the addition of four CO2 molecules.

Implantology is crucial for restoring aesthetics and masticatory function in oral rehabilitation. Despite its advantages, certain issues, such as bacterial infection, may still arise that hinder osseointegration and result in implant rejection. This work aims to address these challenges by developing a biomaterial for dental implant coating based on 45S5 Bioglass® modified by zirconium insertion. The structural characterization of the glasses, by XRD, showed that the introduction of zirconium in the Bioglass network at a concentration higher than 2 mol% promotes phase separation, with crystal phase formation. Impedance spectroscopy was used, in the frequency range of 102–106 Hz and the temperature range of 200–400 K, to investigate the electrical properties of these Bioglasses, due to their ability to store electrical charges and therefore enhance the osseointegration capacity. The electrical study showed that the presence of crystal phases, in the glass ceramic with 8 mol% of zirconium, led to a significant increase in conductivity. In terms of biological properties, the Bioglasses exhibited an antibacterial effect against Gram-positive and Gram-negative bacteria and did not show cytotoxicity for the Saos-2 cell line at extract concentrations up to 25 mg/mL. Furthermore, the results of the bioactivity test revealed that within 24 h, a CaP-rich layer began to form on the surface of all the samples. According to our results, the incorporation of 2 mol% of ZrO2 into the Bioglass significantly improves its potential as a coating material for dental implants, enhancing both its antibacterial and osteointegration properties.

Rapid urban industrialization and agricultural production have led to the discharge of excessive phosphate into aquatic systems, resulting in a rise in water pollution. Therefore, there is an urgent need to explore efficient phosphate removal technologies. Herein, a novel phosphate capture nanocomposite (PEI−PW@Zr) with mild preparation conditions, environmental friendliness, recyclability, and high efficiency has been developed by modifying aminated nanowood with a zirconium (Zr) component. The Zr component imparts the ability to capture phosphate to the PEI−PW@Zr, while the porous structure provides a mass transfer channel, resulting in excellent adsorption efficiency. Additionally, the nanocomposite maintains more than 80% phosphate adsorption efficiency even after ten adsorption–desorption cycles, indicating its recyclability and potential for repeated use. This compressible nanocomposite provides novel insights into the design of efficient phosphate removal cleaners and offers potential approaches for the functionalization of biomass−based composites.

The synthesis, characterisation and application of radiolabelled compounds for use in diagnostic and therapeutic medicine requires a diverse skill set. This article highlights a selection of our ongoing projects that aim to provide new synthetic methods and radiochemical tools for building molecular imaging agents with various radionuclides.

This work is devoted to the study of the adsorption of strontium, yttrium, and zirconium ions by the strong acid cation exchange resin Dowex HCR-s/s. The adsorption of strontium, yttrium, and zirconium ions in batch and dynamic conditions from individual solutions of the studied elements, as well as from their mixture, was studied. It was shown that the dependences of the adsorption of strontium, yttrium, and zirconium ions on agitation time fit well with the pseudo-first-order and Elovich equations. Equilibrium adsorption of all three cations can be described with Langmuir's theory. Column adsorption has shown that Dowex HCR-s/s adsorb all three investigated cations from the acidic medium. The inductively coupled plasma mass spectrometry (ICP-MS) proves that separation of these cations using Dowex HCR-s/s is possible only in highly dilute solutions at a concentration of 10 ng/ml of each element. The basis of separation will be a higher rate of adsorption of tetravalent zirconium, compared with strontium and yttrium. As the concentration of the investigated elements increases to 100 ng/ml, all three cations are adsorbed by the resin in equal amounts and can be separated only using special eluents, such as Ca-EDTA.

A highly sensitive scheme of the determination of selenium in drinking water by electrothermal atomic absorption spectrometry with the on-line preconcentration of gaseous analyte compounds obtained by the UV treatment of an analyzed solution in a graphite furnace (GF) is implemented. A photochemical generator of original design of the type 'UV lamp in a hollow cylindrical reactor' is used. The conditions of the photochemical generation and sorption of gaseous selenium compounds are optimized. The efficiency of a number of permanent sorbent modifiers, such as, metallic iridium, tungsten and zirconium carbides, and mixtures of tungsten and zirconium carbides with activated carbon, at the sorption stage in the GF is estimated. The maximum analytical signals of selenium are recorded using graphite tubes modified by iridium. The analytical scheme is verified by a spike recovery test, the recovery of element additives was 90%. The attained limit of detection for Se(IV) is 4.1 ng/L; the relative standard deviation of the results of replicate determinations is no more than 4.0% at the concentration of Se(IV) in water samples 0.1 [micro]g/L., Author(s): M. Yu. Burylin [sup.1], K. A. Romanovskii [sup.1], E. A. Kaigorodova [sup.2] Author Affiliations: (1) grid.26083.3f, 0000 0000 9000 3133, Faculty of Chemistry and High Technologies, Kuban State University, [...]

This paper reports the application of a new type of material for matrices with high lipid content - zirconium based sorbent (Z-Sep+) which improves fat removal from the extracts for the simultaneous determination of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticide (OCPs) residues in food of animal origin with gas chromatography-mass spectrometry (selected-ion monitoring) detection. The sample preparation was based on the modified QuEChERS method and was evaluated in terms of analyte recoveries, linearity, selectivity, repeatability, limits of detection and quanfication. The obtained results showed that the recovery ratios for both groups of investigated compounds were fit to EU specified ranges with the relative standard deviation lower than 10% for most compounds. In both cases acetonitrile turned out to be better solvent than ethyl acetate taking into account the recovery ratio as well as the purity of the samples. The results show that Z-Sep+ can be successfully applied for the simultaneous determination of OCPs residue and PAHs in food of animal origin., Author(s): Magdalena Surma [sup.1], Anna Sadowska-Rociek [sup.1], Ewa Cieslik [sup.1], Katarzyna Sznajder-Katarzynska [sup.1] Author Affiliations: (1) grid.410701.3, 0000 0001 2150 7124, Malopolska Centre of Food Monitoring, Faculty of Food Technology, [...]

In this study, we analyzed a tooth sample of a renal patient using wavelength-dispersive X-ray fluorescence (WDXRF) spectrometry and Fourier transform infrared (FT-IR) spectrometry to quantify major and trace elements, and heavy and toxic elements in particular. The elements detected and quantified in the tooth sample were calcium (Ca), phosphorus (P), carbon (C), oxygen (O), magnesium (Mg), sodium (Na), chlorine (Cl), sulfur (S), potassium (K), silicon (Si), iron (Fe), aluminum (Al), zinc (Zn), strontium (Sr), chromium (Cr), nickel (Ni), copper (Cu), and zirconium (Zr). FT-IR spectrometry has been used to extract relevant information about the molecular contents of the tooth sample. We have compared our results with those obtained in the laboratory for the healthy subjects, and also with the values reported in the literature as obtained using XRF spectrometry only. Elements found in the tooth sample were correlated with the chronic kidney disease (CKD) of the patients. An outline of the XRF apparatus and applications of XRF as a tool for analyzing to dental specimens are also briefly highlighted., Calcified tissues, such as bones and teeth, contain biological signatures from their living phase. The habitat and nutritional and environmental conditions of people can be determined by monitoring the trace [...]

(89)Zr (t1/2=78.4h), a positron-emitting metal, has been exploited for PET studies of antibodies because of its relatively long decay time and facile labeling procedures. Here, we used (89)Zr to evaluate the pharmacokinetics of long-circulating liposomes over 168h (1week). We first developed a liposomal-labeling method using p-isothiocyanatobenzyl-desferrioxamine (df-Bz-NCS) and df-PEG1k-DSPE. Df-Bz-NCS was conjugated to 1mol% amino- and amino-PEG2k-DSPE, where the 1mol% df-PEG1k-DSPE was incorporated when the liposomes were formulated. Incubation of (89)Zr with df, df-PEG1k, and df-PEG2k liposomes for one hour resulted in greater than 68% decay-corrected yield. The loss of the (89)Zr label from liposomes after incubation in 50% human serum for 48h ranged from ~1 to 3% across the three formulations. Tail vein administration of the three liposomal formulations in NDL tumor-bearing mice showed that the (89)Zr label at the end of the PEG2k brush was retained in the tumor, liver, spleen and whole body for a longer time interval than (89)Zr labels located under the PEG2k brush. The blood clearance rate of all three liposomal formulations was similar. Overall, the results indicate that the location of the (89)Zr label altered the clearance rate of intracellularly-trapped radioactivity and that df-PEG1k-DSPE provides a stable chelation site for liposomal or lipid-based particle studies over extended periods of time.

In the present work, novel organic–inorganic hybrid materials containing boron, zirconium, and phosphorus were synthesized at different molar ratios, using the sol–gel method, starting from zirconyl chloride hexa-hydrate, triethyl borate, and phenyl phosphonic acid as the precursors. The sol–gel process is used for the first time in the present work in order to obtain organic–inorganic hybrids (or the so-called inorganic polymers) containing together boron, zirconium, and phosphorus. The sol–gel syntheses were performed at room temperature in ethanol. Zirconium containing compounds are already well known for their applications in medicine in restorative or prosthetic devices, including dental implants, knee and hip replacements, middle-ear ossicular chain reconstruction, and so on. Zirconium is a strong transition metal, which started to replace hafnium and titanium in the last decade in important applications. On the other hand, boron has the capability (similar to carbon) to form stable covalently bonded molecular networks. In addition to this capability, boron also offers mixed metallic and nonmetallic properties, because of its place on the periodic table, at the border between metals and nonmetals. Boron is responsible for the higher thermal stability of synthesized hybrid compounds. In the structure of those hybrid compounds, zirconium, boron, and phosphorus atoms are always connected via an oxygen atom, by P-O-Zr, Zr-O-Zr, or Zr-O-B bridges.

A series of 8 new complexes of titanium and zirconium with diamido ligands bearing an ethylene and propylene bridge between the two amido groups were synthesized and tested for ethylene polymerization. Titanium complexes bearing an ethylene bridge between the two amido groups showed higher activities than the derivatives with a propylene bridge. In the case of the zirconium complexes, the propylene bridged complexes were more active than the corresponding ethylene bridged. The introduction of bulky groups on the ligand structure resulted in an increase in the activity. DFT calculations were performed to determine the activation energy barriers for different reaction steps. The calculated activation energy for the insertion of ethylene into an M-CH3 bond is in the range of 12.2-16.8 kcal/mol and the activation energy for the chain termination via β-H transfer reaction is 12.5-14.4 kcal/mol.

Abstract Doped niobium zirconium oxides are applied in field‐effect transistors and as special‐purpose coatings. Whereas their material properties are sufficiently known, their crystal structures remain widely uncharacterized. Herein, we report on the comparably mild sol‐gel synthesis of Nb2Zr5O15 and the elucidation of its commensurately modulated structure via neutron diffraction. We describe the structure using the most appropriate superspace as well as the convenient supercell approach. It is part of an α‐PbO2‐homeotypic field with the formula Nb2ZrxO2x+5, which has previously been reported only for x≥5.1, and is closely related to the structure of Hf3Ta2O11. The results, supported by X‐ray diffraction and additional synthesis experiments, are contextualized within the existing literature. Via the sol‐gel route, metastable Nb−Zr−O compounds and their heavier congeners are accessible that shed light on possible structures of these commercially utilized materials.

The conversion of ethanol to 1,3-butadiene was carried out using a treated Zr-based catalyst at a temperature of 350–400 °C with different weight hourly space velocities in a fixed bed reactor. The catalysts used are commercial, but they underwent pretreatment. The commercial catalysts used were ZrO2, Zr(OH)2, 2% CaO-ZrO2, 30% TiO2-ZrO2, 50% CeO2-ZrO2 and 10% SiO2-ZrO2 in their modified or treated form. The characterizations of the catalysts were carried out using XRD, XPS, and TGA. The results indicated that ethanol conversion, yield, and selectivity of 1,3-butadiene operated weight hourly space velocity of 2.5 h−1 using 10% SiO2-ZrO2 were 95%, 80%, and 85%, respectively, at 350 °C. Using 50% CeO2-ZrO2 converted 70% ethanol with a 1,3-butadiene yield of 65%. The best Zr-based catalyst was 10% SiO2-ZrO2 as it gives a steady 1,3-butadiene yield, the Si-composition with ZrO2 gives a good catalytic pour of the catalyst-bed structure; hence, the life span was good. Using 30% TiO2-ZrO2 has an ethanol conversion of 70% with a 1,3-butadiene yield of 43%.

Zirconium-modified Y zeolites (ZrUSY) were prepared by impregnation of the zeolite with anhydrous-ethanol and aqueous ion exchange methods. The ZrUSY samples were characterized by powder X-ray diffraction, nitrogen physisorption, and Fourier transform infrared spectroscopy. The results indicated that ZrUSY prepared by the impregnation with anhydrous-ethanol method showed higher crystallinity, specific surface area and hydrothermal stability. The incorporation of Zr into other Y zeolites leads to an increase of the Brønsted acid site concentration and a decrease of the Lewis acid site concentration compared to the ultra-stable Y zeolite (USY). The ZrUSY was much more favorable towards heavy oil FCC conversion with decreasing coke yield and improving olefins selectivity.

Oxide compounds, as the basis of promising materials, are used in various fields of modern technologies due to their electrical and optical properties. Some of them, possessing a combination of ferroelectric, scintillation, electrical, and optical properties, are being studied as promising materials for electronics. In this case, their dispersion plays an important role. Traditionally, the synthesis of oxide compounds is carried out by ceramic technology. More promising for the synthesis of fine powders are the methods of “soft” chemistry, among which we have identified and applied the sol-gel method. In this method, “mixing” occurs at the molecular level, which contributes to an increase in the reaction rates and a decrease in the synthesis temperature. The method involves the use of inorganic salts as precursors in combination with complexing agents (citric acid). The use of such precursors allows one to achieve high uniformity at relatively low temperatures. A feature of this approach is the use of fewer organic compounds: an aqueous solution of citric acid is used as a chelating agent. The aim of this work was to obtain triple molybdate by sol-gel technology (SGT) based on the example of ironcontaining potassium zirconium molybdate. The iron-containing triple potassium zirconium molybdate was obtained using the of citrate sol-gel technology and solidphase synthesis (SPS) methods. The triple molybdate obtained by two methods was characterized by X-ray phase analysis, DSC, and impedance spectroscopy. The developed sol-gel synthesis technique allowed lowering the synthesis temperature, to obtain triple molybdate with high values of homogeneity, dispersion, and electrical conductivity. This technique can be used to obtain double and triple zirconium (hafnium) molybdates containing a trivalent cation.

The results of elaborating a method for the synthesis of zirconia and hafnia doped by rare earths (yttrium, erbium and scandium) by using low-hydrated hydroxides of zirconium and hafnium as precursors are reported. The low-hydrated zirconium and hafnium hydroxides were prepared using the heterophase reaction. The physicochemical properties (including sorption properties) of low-hydrated zirconium and hafnium hydroxides ZrxHf1-x(OH)3÷1O0.5÷1.5·0.9÷2.9H2Owere studied. The scheme of thermal decomposition of low-hydrated hydroxides in air was determined. The sorption properties of the low-hydrated hafnium hydroxide are less pronounced owing to the lower amount of sorption centers, in this case, hydroxo and aqua groups. The sequence of stages of thermal decomposition of rare earth acetates was elucidated. Single-phase zirconia and hafnia doped by rare earths (yttrium, erbium and scandium) were obtained. The parameters of the elementary lattice were calculated for each phase. It was established that the stabilization of zirconium dioxide with yttria leads to the formation of interstitial solid solutions based on tetragonal zirconia (in the case of the composition Y2O3×4ZrO2 - cubic modification), with erbium oxide - interstitial solid solutions based on cubic zirconia; with scandium oxide - solid solutions based on tetragonal zirconia. The article presents the results of measuring electrical conductivity.

This paper describes the synthesis and characterization of zirconium oxide (ZrO2) and of the mixed oxide of iron (iron zirconate), obtained by gelification (80 °C) and calcination (600 °C) of citrus pectin and inorganic nitrates. Thermal analysis demonstrated the presence of organic matter in the solid after calcination, indicating that pectin was strongly coordinated to the oxide phases. The X-ray diffractogram for zirconate, do not show peaks associated with the iron oxides phases, indicating that the zirconia matrix remained unchanged. Electronic spectra supported observations concerning the color of the solids, with bands assigned to d–d transitions of the iron ions. Both Raman spectra and X-ray diffractogram indicated the presence of the tetragonal phase of ZrO2, and scanning electron microscopy images showed that the solids had similar and particulate morphologies. Finally, the test for dye degradation using iron zirconate proved efficient, with a degradation index greater than 90.3% after 60 min. DOI: http://dx.doi.org/10.17807/orbital.v10i5.980

Detailed monographs on the analytical chemistry of zirconium, which is widely used in all fields of modern science and technology, were published in the 1960s–1970s of the last century. This review summarizes information on the modern methods for determination of zirconium in a great variety of natural, technical, and biological objects. Focus is made on the works published in scientific periodicals after 2005. Spectroscopic techniques of zirconium determination including molecular and atomic spectrometry, X-ray fluorescence analysis, and electrochemical and activation methods are described. The paper also describes the applications of zirconium compounds, in particular, in analytical chemistry.

The Tl2MoO4–R2(MoO4)3–Zr(MoO4)2 (R = Al, Cr) systems were studied in the subsolidus region using X-ray powder diffraction and differential scanning calorimetric (DSC) analysis. Quasi-binary joins were revealed, and triangulation was carried out. New ternary molybdates: Tl5RZr(MoO4)6 (5:1:2) and TlRZr0.5(MoO4)3 (1:1:1) (R = Al, Cr) were prepared. The unit cell parameters for the new compounds were calculated.

Zr-incorporated Gd2O3 films were grown on various substrates as a function of Zr content. The extent of interfacial reactions was found to be critically dependent on both the incorporated Zr content and the substrate type. Specifically, the silicide layer was suppressed and the Gd2O3 phase was changed to ZrO2 on a Si substrate with increasing Zr content. Crystalline Gd2Ge2O7 was grown on a Ge substrate, as the result of interfacial reactions between Gd-oxide and the Ge substrate. However, interfacial reactions were not affected by the amount of Zr incorporated. On the SiGe/Si substrate, reactions between Gd-oxide and Si could be controlled effectively by the incorporation of Zr, while the extent of reactions with Ge was significantly enhanced as the Zr content increased. The formation of an interfacial layer between the film and the SiGe substrate resulted in a textured crystalline growth. [ABSTRACT FROM AUTHOR]

In this prospective clinical trial we observed the 2-year clinical performance of posterior tooth-supported multi-unit fixed dental prostheses (FDP) fabricated from zirconia with monolithic occlusal surfaces. Fifty multi-unit FDPs were inserted in 50 patients. After two years of clinical service, 43 restorations were reexamined as one patient had died and six patients were not available for recall. Two biological (root canal treatment: 12 and 14 months) and one technical (debonding: 12 months) complications occurred. According to the Kaplan–Meier analysis, the success rate was 93.7%, and the survival rate was 100%. The six patients who were not available for regular 2-year follow-up were examined after the official 2-year recall interval, and none of the FDPs presented complications or failures. Within the limitations of the current study, the use of multi-unit FDPs with monolithic occlusal surfaces fabricated from zirconia can be recommended for short-term use in the posterior area.

The present in vivo study determined the microbiological counts of the gingival crevicular fluid (GCF) among patients with fixed dental prostheses fabricated using three different techniques. A total of 129 subjects were divided into three study groups: first, cobalt-chrome-based, metal-ceramic prostheses fabricated by the conventional method (MC, n = 35); the second group consisted of cobalt-chrome-based, metal-ceramic prostheses fabricated by the computer-aided design and computer-aided manufacturing (CAD/CAM) technique (CC-MC, n = 35); the third group comprised zirconia-based ceramic prostheses fabricated using the CAD/CAM technique (CC-Zr, n = 35). The control consisted of 24 patients using prostheses fabricated with either MC, CC-MC, or CC-Zr. The GCF was obtained from the subjects before treatment, and 6 and 12 months after the prosthetic treatment. Bacteriological and bacterioscopic analysis of the GCF was performed to analyze the patients’ GCF. The data were analyzed using SPSS V20 (IBM Company, Chicago, IL, USA). The number of microorganisms of the gingival crevicular fluid in all groups at 12 months of prosthetic treatment reduced dramatically compared with the data obtained before prosthetic treatment. Inflammatory processes in the periodontium occurred slowly in the case of zirconium oxide-based ceramic constructions due to their biocompatibility with the mucous membranes and tissues of the oral cavity as well as a reduced risk of dental biofilm formation. This should be considered by dentists and prosthodontists when choosing restoration materials for subjects with periodontal pathology.

Five novel air- and moisture-stable polymetallic Ti and Zr amino acid-derived amine bis(phenolate) (ABP) complexes were synthesised and fully characterised, including X-ray crystallographic studies. The reaction of the ABP proligands with Ti or Zr alkoxides has resulted in the formation of polymetallic aggregates of different nuclearity. The steric bulk on the pendant arm of the ligand was found to play a critical role in establishing the nuclearity of the aggregated complex. Sterically, less-demanding groups, such as H or Me, facilitated the formation of tetrametallic Ti clusters, bridged by carboxylate groups, while increased steric bulk (tBu) led to the formation of binuclear μ-oxo-bridged species. The isolated complexes were employed as catalysts for the ring opening polymerisation (ROP) of rac-lactide. Overall, the Ti catalysts were all active with the smaller, bimetallic Ti aggregates exhibiting relatively faster rates. A monometallic, bis(ABP) Zr complex was found to exert remarkable ROP activity, albeit with limited control over the tacticity and molecular weight distribution of the polymer. A further oxo-bridged Zr cluster was shown to display a previously unprecedented trimetallic structure and achieved a moderate rate in the ROP of rac-lactide.

Anodization enables fabrication of controlled nanotopographies on Ti implants to offer tailorable bioactivity and local therapy. However, anodization of Zr implants to fabricate ZrO2 nanostructures remains underexplored and are limited to the modification of easy-to-manage flat Zr foils, which do not represent the shape of clinically used implants. In this pioneering study, we report extensive optimization of various nanostructures on implant-relevant micro-rough Zr curved surfaces, bringing this technology closer to clinical translation. Further, we explore the use of sonication to remove the top nanoporous layer to reveal the underlying nanotubes. Nano-engineered Zr surfaces can be applied towards enhancing the bioactivity and therapeutic potential of conventional Zr-based implants.

Ultrahigh molecular weight polyethylene (UHMWPE) is a class of high-performance engineering plastics, exhibiting a unique set of properties and applications. Although many advances have been achieved in recent years, the synthesis of UHMWPE is still a great challenge. In this contribution, a series of zirconium and hafnium complexes, [2,6-(R1)2-4-R2-C6H2-N-C(camphyl)=C(camphyl)-N-2,6-(R1)2-4-R2-C6H2]MMe2(THF) (1-Zr: R1 = Me, R2 = H, M = Zr; 2-Zr: R1 = Me, R2 = Me, M = Zr; 1-Hf: R1 = Me, R2 = H, M = Hf; 2-Hf: R1 = Me, R2 = Me, M = Hf), bearing bidentate NN ligands with the bulky camphyl backbone were synthesized by the stoichiometric reactions of α-diimine ligands with MMe4 (M = Hf or Zr). All Zr and Hf metal complexes were analyzed using 1H and 13C NMR spectroscopy, and the molecular structures of complexes 1-Zr and 1-Hf were determined by single-crystal X-ray diffraction, revealing that the original α-diimine ligand was selectively reduced into the ene-diamido form and generated an 1,3-diaza-2-metallocyclopentene ring in the metal complexes. Zr complexes 1-Zr and 2-Zr showed moderate activity (up to 388 kg(PE)·mol−1(M)·h−1), poor copolymerization ability, but unprecedented molecular weight capability toward ethylene/1-octene copolymerization. Therefore, copolymers with ultrahigh molecular weights (>600 or 337 × 104 g∙mol−1) were successfully synthesized by 1-Zr or 2-Zr, respectively, with the borate cocatalyst [Ph3C][B(C6F5)4]. Surprisingly, Hf complexes 1-Hf and 2-Hf showed negligible activity under otherwise identical conditions, revealing the great influence of metal centers on catalytic performances.