Using the first-principles particle swarm optimization algorithm for crystal structural prediction, we have predicted a novel monoclinic C2/m structure for ZrB₃, which is more energetically favorable than the previously proposed FeB₃-, TcP₃-, MoB₃-, WB₃-, and OsB₃-type structures in the considered pressure range. The new phase is mechanically and dynamically stable, as confirmed by the calculat...

The reactivity of the geminal dianion of tetraisopropyl methylenediphosphonate, 3, with [ZrCl4(THF)2] affords a trinuclear structure 5 in which an unprecedented triscarbene-Zr dianionic fragment is found. The overall trinuclear arrangement is assembled by PO bridging moieties. The X-ray crystal structure of 5 is presented. The reaction of complex 5 with stoichiometric amounts of pyridine afford...

The effects of zirconium (Zr) on T cells and macrophages in mice were studied in vitro using the indexes of immunological reactions, mitogenesis of C3H/HeJ mouse thymocytes induced by PHA and the production of interleukin-1 of C3H/He mouse intraperitoneal macrophages (MIL-1). The mitogenesis of thymocytes induced by PHA when stimulated with Zr solutions at various concentrations or culture supe...

An improved methodology of the Zr specimen preparation was developed which allows fabrication of stable Zr nanotips suitable for FIM and AP applications. Initial oxidation of the Zr surface was studied on a Zr nanotip by FIM and on a polycrystalline Zr foil by XPS, both at low oxygen pressure (10(-8)-10(-7)mbar). The XPS data reveal that in a first, fast stage of oxidation, a Zr suboxide interl...

The reaction of [Zr(TrenDMBS )(Cl)] [Zr1; TrenDMBS =N(CH2 CH2 NSiMe2 But )3 ] with NaPH2 gave the terminal parent phosphanide complex [Zr(TrenDMBS )(PH2 )] [Zr2; Zr-P=2.690(2) Å]. Treatment of Zr2 with one equivalent of KCH2 C6 H5 and two equivalents of benzo-15-crown-5 ether (B15C5) afforded an unprecedented example (outside of matrix isolation) of a structurally authenticated transition-metal...

With the motivation of exploring new high-strength ceramics, ab initio evolutionary simulations are performed to search for all the stable compounds in the Zr-O system. We have found that not only the traditional compound ZrO2, but also the ordered suboxides R3̅-Zr6O, R3̅c-Zr3O, P3̅1m-Zr2O and P6̅2m-ZrO are stable at zero pressure. The crystal structure of semimetallic P6̅2m-ZrO consists of Zr-graph...

Effective tribofilms are desirable to protect mechanical systems. In the present research, we investigated the formation of a tribofilm through the use of α-ZrP (Zr(HPO4)2 ̈H2O) as an additive. Experiments were conducted on a base oil where 0.2 wt% of the additive was used. Experimental results showed a 50% reduction in friction and a 30% reduction in wear when compared to the base oil containin...

Single-layered zirconium oxynitride (ZrNxOy) thin films have been deposited on steel substrates, at a constant temperature of 300 8C, by radiofrequency (rf) reactive magnetron sputtering of a pure Zr target in an argon–oxygen–nitrogen atmosphere. The variation of the flow rate of the reactive gases enabled changes in the composition and structure of the films. X-ray diffraction (XRD) and glanci...

A zirconium modified MCM-48 mesoporous material was synthesized by surfactant-templated method. Surface grafting Zr-MCM-48 with tungstophosphoric acid led to a great enhancement of both the number of the Brønsted acid sites and acidity strength in comparison with the bare support. At 100 ̊C, the 30 wt% H3PW12O40/Zr-MCM-48 contained 174 mol/g Brønsted acid sites which were 21.7 times greater tha...

Lifetimes on the sub-nanosecond scale for the levels vD3/2, vF3/2 and vF5/2 in the 4d5s5p configuration in Zr II have been measured, using the method of laser-induced fluorescence. Combined with branching fractions obtained with the Lund Ultraviolet (UV) Fourier Transform Spectrometer (FTS), experimental oscillator strengths have been derived. From Hubble Space Telescope/Goddard High-Resolution...