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    Influence of the molecular groups ordering on structural phase transitions in (NH4)2WO2F4 crystal
/ A. S. Krylov [et al.] // Cryst. Growth Des. - 2014. - Vol. 14, Is. 1. - P. 374-380, DOI 10.1021/cg400899m. - Cited References: 27. - This work was partly supported by the Russian Foundation for the Basic Research project no. 12-02-00056, no. 13-02-00825, and integration project SB RAS no. 28, SS-4828.2012.2. - Published as part of the Crystal Growth & Design virtual special issue Anion-controlled New Inorganic Materials. . - ISSN 1528-7483. - ISSN 1528-7505
РУБ Chemistry, Multidisciplinary + Crystallography + Materials Science, Multidisciplinary

Аннотация: Phase transitions of the (NH4)2WO2F 4 crystal were studied by Raman spectroscopy in the range from 10 to 350 K. The mechanism of two phase transitions at T1 = 201 and T 2 = 160 K was proposed. The significant spectra changes occur in the range corresponding to the W-O vibrations. The first temperature phase transition is due to the ordering of the quasi-octahedral groups [WO 2F4]2- and partial ordering of ammonium groups. Experimental data allow for attributing the first (T1 = 201 K) phase transition to the first order close to the tricritical point. The noticeable changes of the Raman spectrum have been found in the range corresponding to the ammonium vibrations below the temperature T2. The second phase transition is associated with the further ordering of ammonium groups. Room temperature (296 K) experiments have been carried out under high hydrostatic pressure up to 10 GPa. Above 2 GPa, new spectral features appear, allowing for the assumption of the existence of a new high-pressure phase of (NH 4)2WO2F4, which is mainly connected with ordering of the [WO2F4]2- quasi-octahedral groups.

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Держатели документа:
Kirensky Inst Phys SB RAS, Krasnoyarsk 660036, Russia
Inst Geol & Mineral SB RAS, Novosibirsk 630090, Russia
Inst Chem FEB RAS, Vladivostok 690022, Russia

Доп.точки доступа:
Krylov, A. S.; Крылов, Александр Сергеевич; Goryainov, S. V.; Laptash, N. M.; Vtyurin, A. N.; Втюрин, Александр Николаевич; Mel'nikova, S. V.; Мельникова, Светлана Владимировна; Krylova, S. N.; Крылова, Светлана Николаевна

    Thermal expansion, phase diagrams and barocaloric effects in (NH4)(2)NbOF5
/ M. . Gorev [et al.] // J. Phys.: Condens. Matter. - 2010. - Vol. 22, Is. 18. - Ст. 185901, DOI 10.1088/0953-8984/22/18/185901. - Cited References: 17. - This work was supported in part by the Krasnoyarsk Regional Foundation for Support of Scientific and Scientific-Technological Investigations and RFBR in the framework of project 'Siberia' (Grant No. 09-02-98001), and the Council on Grants from the President of the Russian Federation for Support of Leading Scientific Schools (project No. Nsh-1011.2008.2). . - ISSN 0953-8984
РУБ Physics, Condensed Matter

Аннотация: The thermal expansion along the a, b and c axes of a (NH4)(2)NbOF5 crystal was measured from 120 to 300 K. Anomalies of alpha(T) associated with previously reported phase transitions Cmc2(1) -> C-2 -> I a were observed along all directions at T-1 = 259.3 K and T-2 = 220.5 K. The analysis of thermal expansion and heat capacity in the frame of the Pippard relations has permitted us to determine the uniaxial pressure derivatives of the transition temperatures dT/d sigma(i). The T-sigma(i) phase diagrams have shown a tendency for the intermediate phase to disappear at high stress along the b and c axes. Intensive and extensive barocaloric effects near the structural phase transitions were found to be comparable with the caloric parameters of some ferroelectrics, ferromagnets and antiferromagnets.

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Держатели документа:
[Gorev, Michail
Bogdanov, Evgeny
Flerov, Igor] Russian Acad Sci, Siberian Div, LV Kirensky Phys Inst, Krasnoyarsk 660036, Russia
[Gorev, Michail
Flerov, Igor] Siberian Fed Univ, Inst Engn Phys, Krasnoyarsk 660041, Russia
[Laptash, Nataly] Russian Acad Sci, Far Eastern Div, Inst Chem, Vladivostok 690022, Russia
ИФ СО РАН
LVKirensky Institute of Physics, Siberian Division, Russian Academy of Sciences, Krasnoyarsk, Akademgorodok 660036, Russian Federation
Institute of Engineering Physics, Siberian Federal University, av. Svobodny 79, Krasnoyarsk 660041, Russian Federation
Institute of Chemistry, Far Eastern Division, Russian Academy of Sciences, Vladivostok 690022, Russian Federation

Доп.точки доступа:
Gorev, M.; Bogdanov, E. V.; Богданов, Евгений Витальевич; Flerov, I. N.; Флёров, Игорь Николаевич; Laptash, N. M.

    Simultaneous ion exchange recovery of platinum and rhodium from chloride solutions
/ O. N. Kononova [et al.] // Hydrometallurgy. - 2011. - Vol. 105, Is. 3-4. - P. 341-349, DOI 10.1016/j.hydromet.2010.11.009. - Cited Reference Count: 46 . - JAN. - ISSN 0304-386X

Рубрики:
GROUP-METALS PGM
   SEPARATION

   CATALYST

   ANION

   ADSORPTION

   EXTRACTION

   CHEMISTRY

   RESIN

Кл.слова (ненормированные):
platinum -- rhodium -- sorption -- anion exchangers -- chloride solutions -- anion exchangers -- chloride solutions -- platinum -- rhodium -- sorption -- ammonium thiocyanate -- anion exchangers -- basic parameters -- chemical structure -- chloride solutions -- diffusion coefficients -- distribution coefficient -- exchange capacities -- kinetic properties -- noble metals -- purolite -- rhodium chloride -- separation factors -- sorption ability -- work focus -- ammonium compounds -- chlorine compounds -- desorption -- hydrochloric acid -- ion exchange -- ion exchange resins -- ions -- platinum -- platinum compounds -- potassium hydroxide -- precious metals -- recovery -- rhodium -- sulfuric acid -- thioureas -- urea -- rhodium compounds

Аннотация: This work focuses on the sorption recovery of platinum (II, IV) and rhodium (III) simultaneously present in chloride solutions, freshly prepared and stored over 3 months, on commercial anion exchangers with different physical and chemical structure. The sorption was carried out from solutions with 0.001-4.0 mol/L HCl. The initial platinum and rhodium concentrations in contacting solutions were 0.25-2.5 mmol/L Sorption and kinetic properties of the chosen anion exchangers were investigated and the basic parameters of exchange capacity, recovery, distribution coefficients, separation factors, process rate, diffusion coefficients and half-exchange times were calculated. It is shown that anion exchangers investigated possess high sorption ability to platinum and rhodium chloride complexes, which does not deteriorate in case of stored solutions. Desorption of platinum and rhodium from the resins investigated was carried out with hydrochloric acid (2 mol/L), thiourea (1 mol/L) in sulfuric acid (2 mol/L) or in potassium hydroxide (2 mol/L) as well as by ammonium thiocyanate (2 mol/L). It was shown that complete separation of platinum and rhodium can be carried out with 2 mol/L HCl on anion exchanger Purolite S 985, whereas 2 mol/L NH(4)SCN as an elution agent leads to complete separation of noble metals on anion exchangers Purolite S 985, Purolite A 500 and AM-2B. (C) 2010 Elsevier B.V. All rights reserved.

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Держатели документа:
Siberian Fed Univ, Dept Chem, Krasnoyarsk 660041, Russia
Russian Acad Sci, LV Kirensky Phys Inst, Siberian Dept, Krasnoyarsk 660036, Russia

Доп.точки доступа:
Kononova, O.N.; Melnikov, A.M.; Borisova, T.V.; Krylov, A. S.; Крылов, Александр Сергеевич