- Dielectric characterization and ionic conductivity of α-LiIO3 crystals related to the growth conditions
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The dielectric response of α-LiIO3 has been studied at room temperature between 20 Hz and 1 MHz with various types of electrodes and compared to the results in the literature. By changing the sample thickness, a relaxation of space charges is clearly identified and the bulk ionic conductivity is deduced from the admittance diagram. Finally a comparison is carried out between chromium doped and undoped crystals obtained from acid and neutral growth solutions.
- Mugnier,Galez,Crettez,Bourson,Bouillot
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- Thermolysis of disubstituted lithium and sodium orthoperiodates
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Na2H3IO6 decomposes with water and oxygen evolution in the range of 180-250°C under the atmospheric pressure or in a dynamic vacuum. The solid residue is an equimolar mixture of NaIO3 and Na3IO5. Na3IO5 likely occurs in the form of the dimer Na6I2O10. An intermediate thermolysis stage is the elimination of a water molecule from the salt molecule with simultaneous disproportionation of the salt to trisubstituted orthoperiodate and metaperiodate: Na2H3IO6 = 0.5Na3H2IO6 + 0.5NaIO4 + H 2O. Li2H3IO6 thermolysis under the atmospheric pressure proceeds in the same way; however in vacuum, the thermolysis yields LiIO3 and Li5IO6 in the ratio of 3: 1 (mol/mol). The reason for the different thermolysis routes lies in the different stability of the intermediates M3H2IO 6 and MIO4. Nauka/Interperiodica 2007.
- Nikitina,Nikitina
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- Electrical conductivity of α-LiIO3 acid type crystals at 1 kHz
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The temperature dependence of the electrical conductivity of α-LiIO3 acid type crystals is studied. By applying a very low amplitude electric field at 1 kHz and performing a continuous sampling of measurements, differences, reproducible for all the investigated samples, appeared between the first and subsequent heatings The anomalies occurring during the first heating are attributed mainly to inclusions of mother liquor, HIO3 and Li1-xHxIO3. The 'intrinsic' conductivity is measured after a first annealing at about 470 K; the activation energies are then calculated.
- Ke, San-huang,Wang, Ren-zhi,Huang, Mei-chun
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p. 1013 - 1018
(2008/10/08)
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- The Crystal Structure of Lithiummetaperiodate, LiIO4
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For the first time single crystals of LiIO4 were obtained. According to the results of an X-ray structure determination (monoclinic, P21/N; a=525.5(3), b=851.1(4), c=796.9(5) pm, β=104.21(3)°; Z=4; 2148 diffractometer data, R=0.024) the coordination by oxygen is tetrahedral for iodine and strongly distorted trigonal bipyramidal for lithium. Two lithium-oxygen-polyhedra are connected via a common edge. LiIO4 crystallises isostructural to LiAlH4. The structure is discussed and compared to those of other metaperiodates and tetrahydridoaluminates.
- Kraft, Thorsten,Jansen, Martin
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- OXIDATION OF ALKALI METAL IODATES IN MOLTEN ALKALI METAL NITRATES
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Alkali metal iodates MIO3 (M=Li, Na, K) were oxidized in the presence of hydroxides MOH in molten nitrates MNO3 with oxygen or ozone.The following products were precipitated at variable MOH:MIO3 rations and then separated from the melts and identified after purification with liquid ammonia: Li5IO6, Na4IO5, Na5IO6, K2IO4, K3IO5.Two of these substances, Na4IO5 and K2IO4 contain formally hexavalent iodine and were studied by X-ray powder method, IR spectroscopy and measurements of the magnetic susceptibility.Their thermodynamic stability was also investigated.Periodates Na5IO6 and K3IO5 have been pepared for the first time from a homoge neous mixture by precipitation with an oxidizing agent.
- Dratovsky, M.,Dvorakova, E.,Rytir, Z.
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p. 175 - 182
(2007/10/02)
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- Low-temperature Specific Heat of the Hexagonal (α) and the Tetragonal (β) Modification of Lithium Iodate
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The specific heat of α- and β-LiIO3 has been studied by adiabatic calorimetry at 10-335 K.No anomalies have been found in the Cp-T curves.The thermodynamic functions of α- and β-LiIO3 under standard conditions have been calculated.
- Gorbunov, V. E.,Gavrichev, K. S.,Zalukaev, V. L.,Totrova, G. A.,Kidyarov, B. I.
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p. 1649 - 1652
(2007/10/02)
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