Nano-ZrO2@C, Nano-(ZrC, ZrO2)@C and Nano-ZrC@C Composites Prepared by Plasma-Assisted Carbonization of Zr-Loaded Iminodiacetate-Functionalized Styrene-Divinylbenzene Copolymers

Abstract

We have developed an easy route to prepare (nano-ZrO2,nano-ZrCx)@C composites with varying ZrO2/ZrCx content. The process consists of preparing a zirconium-loaded, iminodiacetate-functionalized styrene-divinylbenzene (STY-DVB) copolymer, and its subsequent carbonization in a tube furnace and/or a thermal plasma reactor. Depending on the zirconium salt used (zirconyl chloride, zirconyl nitrate or zirconium (IV) sulfate) in the Zr loading, the Zr-loaded resins resulted in ZrO2@C pre-pyrolizates with C to Zr molar ratios of 5.8, 6.8 and 6.60. This carbon surplus is sufficient for the partial or even complete reduction of ZrO2 into ZrC0.58 at 1400 °C. The reaction products also contain 5 to 55 mass% residual free carbon. The plasma processing of the ZrO2@C composite formed at 1000 °C in a tube furnace led to ZrC0.94@C composites. The transformation of amorphous carbon content during the plasma treatment strongly depended on the atmosphere (He or H2) in the reactor and the anion type of the Zr salt. In the presence of He, amorphous carbon could be completely transformed into graphite. In the presence of H2, amorphous carbon and graphite were found at roughly the same ratio. No ZrO2 could be detected in the plasma-treated samples, whilst different ZrO2 polymorphs were found in the samples prepared in the tube furnace, depending on the synthesis conditions.

Crystal Nanoarchitectonics and Characterization of the Octahedral Iron(III)–Nitrate Complexes with Isomer Dimethylurea Ligands

“…Powder X-ray tests were performed with a Philips PW-1050 Bragg-Brentano parafocusing goniometer equipped with a copper cathode (40 kV, 35 mA, secondary beam graphite monochromator, proportional counter). Scans were recorded in step mode, and the diffraction patterns were evaluated with a full profile fitting technique [34,35].…”

Carbonization of Zr-Loaded Thiourea-Functionalized Styrene-Divinylbenzene Copolymers: An Easy Way to Synthesize Nano-ZrO2@C and Nano-(ZrC, ZrO2)@C Composites

“…Thermogravimetric analysis, differential scanning calorimetry, and mass spectrometric evolved gas analysis were performed simultaneously with the use of the SETARAM Labsys Evo (Lyon, France) and the Pfeiffer Vacuum OmniStar (Asslar, Germany) instruments under a He atmosphere (heating rate 20 • C/min, 25-1000 • C). The details of the thermal analysis were given in [5,6].…”

“…Therefore, a correction with the use of the amorphous carbon/graphite ratio was used (from the Raman data) in our estimations. The ratio of crystalline phases was estimated with XRD as given in [5,6]. The size of ZrO 2 and ZrC crystallites were determined by the Scherrer method.…”

“…Radiolytically stable amorphous carbon and graphite composites containing ZrC and ZrO 2 have enormous strategic importance in the nuclear industry owing to their advantages such as high mechanical strength, a high adsorption capacity towards fission products, and a large neutron absorption cross-section [1][2][3][4]. A recently developed method to synthesize carbon composites containing metal oxides is based on the carbonization of ion exchangers with various functional groups (sulfonate, iminodiacetate) [5,6]. Some metals like titanium or zirconium form carbides at higher temperatures or during plasma treatment [7][8][9].…”

“…ZrC@C or (ZrC, ZrO 2 )@C composites were prepared from Zrloaded sulfonate-, iminodiacetate-, or dimethylamine-functionalized ion-exchanger resins loaded with cationic, complexed, or anionic Zr-species, respectively. The functional groups strongly influence carbide formation despite the loss of the functional groups below 500 • C owing to differences in the reactivity of the intermediates that formed from the various functionalized polymers [5,6,10,11]. The sulfonate-, iminodiacetate-, and dimethylaminefunctionalized ion exchangers have S and O, N and O, and only N heteroatom-containing functional groups bound to zirconium.…”