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    Crystal structures and Hirshfeld surface analysis of transition-metal complexes of 1,3-azolecarboxylic acids
    (2019-09-01)
    Meundaeng, Natthaya
    ;
    Prior, Timothy John
    ;
    Rujiwatra, Apinpus
    The crystal structures of five new transition-metal complexes synthesized using thiazole-2-carboxylic acid (2-Htza), imidazole-2-carboxylic acid (2-H2ima) or 1,3-oxazole-4-carboxylic acid (4-Hoxa), namely diaquabis(thiazole-2-carboxylato-κ<sup>2</sup> N,O)cobalt(II), [Co(C4H2NO2S)2(H2O)2], 1, diaquabis(thiazole-2-carboxylato-κ<sup>2</sup> N,O)nickel(II), [Ni(C4H2NO2S)2(H2O)2], 2, diaquabis(thiazole-2-carboxylato-κ<sup>2</sup> N,O)cadmium(II), [Cd(C4H2NO2S)2(H2O)2], 3, diaquabis(1H-imidazole-2-carboxylato-κ<sup>2</sup> N <sup>3</sup>,O)cobalt(II), [Co(C4H2N2O2)2(H2O)2], 4, and diaquabis(1,3-oxazole-4-carboxylato-κ<sup>2</sup> N,O <sup>4</sup>)cobalt(II), [Co(C4H2NO3)2(H2O)2], 5, are reported. The influence of the nature of the heteroatom and the position of the carboxyl group in relation to the heteroatom on the self-assembly process are discussed based upon Hirshfeld surface analysis and used to explain the observed differences in the single-crystal structures and the supramolecular frameworks and topologies of complexes 1-5.
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    Crystal structure of (1,3-thiazole-2-carboxylato-κ N)(1,3-thiazole-2-carboxylic acid-κ N)silver(I)
    (2019-01-01)
    Meundaeng, Natthaya
    ;
    Rujiwatra, Apinpus
    ;
    Prior, Timothy J.
    The linear two-coordinate silver (I) complex [Ag(C 4 H 2 NO 2 S)(C 4 H 3 NO 2 S)] or [Ag(2-Htza)(2-tza)] is reported (2-Htza = 1,3-thiazole-2-carboxylic acid). The Ag I ion is coordinated by two heterocyclic N atoms from two ligands in a linear configuration, forming a discrete coordination complex. There is an O - H⋯O hydrogen bond between 2-tza - and 2tzaH of adjacent complexes. The hydrogen atom is shared between the two oxygen atoms. This interaction produces a hydrogen-bonded tape parallel to the [110] direction, which is augmented through intermolecular C - H⋯O hydrogen-bonding interactions between the bound thiazole groups. There is a further rather long Ag⋯O interaction [2.8401 (13) Å, compared with a mean of 2.54 (11) Å for 23 structures in the CSD] that assembles these tapes into columns, between which there are C - H⋯π interactions, leading to the formation of a three-dimensional supramolecular architecture.
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    Low firing temperatures and high ferroelectric properties of (Ba0.85Ca0.15)(Ti 0.90Zr0.10)O3 lead-free ceramics synthesized by the combustion technique
    (2016-01-26)
    Kornphom, Chittakorn
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    This work studied the effect of firing conditions on phase formation, microstructure and electrical properties of (Ba<inf>0.85</inf>Ca<inf>0.15</inf>)(Ti<inf>0.90</inf>Zr<inf>0.10</inf>)O<inf>3</inf>;(abbreviated as BCTZ) ceramics, which were synthesized through the combustion technique. To reduce the reaction temperature, glycine was used as fuel with a ratio of raw material: glycine (1:1.11). BCTZ samples were calcined at 900-1200°C for 2 h and sintered at 1350 -1550°C for 2 h. Ultrafine BCTZ powder and single peroveskite phase were achieved from the sample calcined at 1050°C for 2 h.These results were obtained at a lower temperature and with shorter dwell time than those obtained using the solid state reaction method by ∼150°C and 1 h, respectively. The BCTZ ceramics exhibited a coexistence of rhombohedral and orthorhombic phase in all samples. The average particle size and the average grain size increased from 172 to 295 nm and 0.82 to 2.57 μm, respectively, when firing temperatures increased. The highest density (5.76 g/cm<sup>3</sup>), highest dielectric constant (ε<inf>r</inf> ≅ 4485 and ε<inf>max</inf> ≅ 14897) and best ferroelectric properties (P<inf>r</inf> ≅ 18.47 C/cm<sup>2</sup> and E<inf>C</inf> ≅ 4.52 kV/cm) were obtained from the sample sintered at 1450°C for 2 h.
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    Fabrication of new (Ba0.97Ca0.03)(Zr0.94Sn0.06)O3 ceramics by the combustion technique
    (2016-01-26)
    Mathrmool, Krailas
    ;
    Vittayakorn, Naratip
    ;
    Bongkarn, Theerachai
    In this study, new (Ba<inf>0.97</inf>Ca<inf>0.03</inf>)(Zr<inf>0.94</inf>Sn<inf>0.06</inf>)O<inf>3</inf> BCZS ceramics were synthesized by the combustion technique using glycine as fuel. The powders and ceramics were calcined from 1,000 to 1,200 °C for 2 h and sintered from 1,500 to 1,675 °C for 2 h. A pure perovskite phase was found in the powder calcined at higher than 1,150 °C and the purity phase of the ceramics was detected in all samples. The average particle size and grain size increased approximately from 73 to 103 nm and from 0.51-1.61μm when firing temperatures increased. The calcined powders exhibited tight agglomerates at low calcination temperatures and they changed to loosely bound agglomerates at higher calcination temperatures. The densest ceramics were discovered in the samples sintered at 1,650 °C. The dielectric constant (ε<inf>r</inf>) and loss factor (tan δ) values measured at 100 kHz of this sample were found to be 44 and 0.01, respectively at room temperature.
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    First principles calculations on crystal and electronic structure of Co2P4O12
    (2014-09-02)
    Rerksompus, Pathompong
    ;
    Sarasamak, Kanoknan
    ;
    Boonchom, Banjong
    ;
    Thanomngam, Pitiporn
    Crystal and electronic structure of violet-pink Co<inf>2</inf>P <inf>4</inf>O<inf>12</inf> have been investigated using first principles calculations based on density functional theory. Its theoretical X-ray diffraction and X-ray absorption fine structure spectra were calculated and compared with their experimental spectra to verify its monophasic. The calculated spectra are in good agreement with the experimental data giving parameters of a = 11.993 Å, b = 8.328 Å, c = 10.150 Å and β = 118.51°. Our calculations on band structure and density of states of Co<inf>2</inf>P<inf>4</inf>O<inf>12</inf> showed that its major electronic transition is associated with internal Co-3d. The calculations indicated that Co<inf>2</inf>P<inf>4</inf>O<inf>12</inf> is a half metal ferromagnetic material which disagreed with the experimental knowledge. © 2014 Taylor & Francis Group, LLC.
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