In the course of the last years hexacyanoferrates have been widely studied; even though, the adsorption properties of Zn (II) hexacyanoferrate(II) (labelled here Zn-HII) have not been thoroughly considered. In addition, soft porous crystals, i.e., adsorbents that display structural flexibility have been, as well, extensively studied, however this property has not been reported for Zn (II) hexacyanoferrate(II). In this regard, the key questions addressed here were the synthesis and structural characterization of Zn-HII together with the investigation of their low (up to 1 bar) and high pressure (up to 30 bar) adsorption properties, to found if these materials show structural flexibility. Then, to attain the anticipated goals, structural characterizations were made with: X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) and thermo-gravimetric analysis (TGA), simultaneously, with the investigation of the adsorption of carbon dioxide. As a result of the research process we concluded that the Zn-HII displayed Fm3m space group framework. Besides, the carbon dioxide adsorption investigation demonstrated the presence of the framework expansion effect together with an extremely high adsorption heat, properties that could be useful for the use of Zn(II) hexacyanoferrate(II) as an excellent adsorbent. (C) 2016 Elsevier B.V. All rights reserved.

A mixture of akaganeite nanoparticles and sodium salts was synthesized and modified, first by washing, and then by Li exchange. The structural characterization of the produced materials was performed with: powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, thermogravimetric analysis, diffuse reflectance infrared Fourier transform spectrometry, Mossbauer spectroscopy and magnetization measurements. Additionally low pressure nitrogen and high pressure carbon dioxide adsorption experiments were performed. The sum of the characterization information made possible to conclude that the produced akaganeite phases crystallized in a structure exhibiting the symmetry of the I2/m space group, where the measured equivalent spherical diameter of the akaganeite crystallites yielded 9 nm, as well, the tested phases exhibited a standard behaviour under heating and displayed a superparamagnetic behaviour. Finally the high pressure carbon dioxide adsorption experiments demonstrated a pressure-responsive framework opening event due to a structural transformation of the adsorbent framework induced by the guest molecules. This fact opens new applications for akaganeite as a high pressure adsorbent. (C) 2015 Elsevier B.V. All rights reserved.

The key questions addressed here were: the structure elucidation and the investigation of the adsorption space and framework expansion effect of a Cu(II) hexacyanoferrate (III) polymorph (labeled Cu-PBA-I). The structural analysis was performed with a broad set of characterization methods. Additionally, a low and high pressure carbon dioxide adsorption investigation was performed, assuming, to comprehend the adsorption experiments, that the adsorbent plus the adsorbed phase were a solid solution. We concluded: that the Cu-PBA-I presented the following composition, K1/4Cu(II)[Fe(III)(CN)6]3/4⋄1/4nH2O, exhibited an antiferromagnetic behavior and displayed a thermally stable I4¯m2 space group lattice in the degassed state. Moreover, the low pressure adsorption study allowed the calculation of the micropore volume, W=0.09cm3/g and the isosteric heat of adsorption, qiso=19kJ/mol; further, the high pressure adsorption data revealed an extremely high adsorption capacity owing to a framework expansion effect. Finally, the DRIFTS spectrum of adsorbed CO2 displayed peaks corresponding to carbon dioxide physically adsorbed and interacting with electron accepting Lewis acid sites. Hence, was produced an excellent adsorbent which combine porosity and anti-ferromagnetism, antagonist properties rarely found together.

The properties of phosphorus doped ZnO thin films grown on sapphire by pulsed laser deposition were examined, specifically focusing on the effects of undoped ZnO buffer layers. In particular, buffer layers were grown under different conditions; the transport properties of as-deposited and rapid thermal annealed ZnO : P films were then examined. As-deposited films showed n-type conductivity. After rapid thermal annealing, the film on buffer layer grown at a low temperature showed the conversion of carrier type to p-type for specific growth conditions while the films deposited on buffer layer grown at a high temperature remained n-type regardless of growth condition. The films deposited on buffer layer grown at a low temperature showed higher resistivity and more significant change of the transport properties upon rapid thermal annealing. These results suggest that more dopants are incorporated in films with higher defect density. This is consistent with high resolution x-ray diffraction results for phosphorus doped ZnO films on different buffer layers. In addition, the microstructure of phosphorus doped ZnO films is substantially affected by the buffer layer.

A careful structural characterization was carried out to unequivocally determine the structure of the synthesized material. The TGA, DRIFTS and a Pawley fitting of the XRD powder profiles indicate that the hydrated and in situ dehydrated polymorph crystallizes in the orthorhombic space group Pnma. Meanwhile, the CO2 isosteric heat of adsorption appears to be independent of loading with an average value of 30kJ/mol. This translates to a physisorption type interaction, where the adsorption energy corresponding to wall and lateral interactions are mutually compensated to produce, an apparently, homogeneous adsorption energy. The somewhat high adsorption energy is probably due to the confinement of the CO2 molecules in the nitroprusside pores. Statistical Physics and the Dubinin theory for pore volume filling allowed model the CO2 equilibrium adsorption process in Cu-nitroprusside. A DRIFTS test for the adsorbed CO2 displayed a peak at about 2338cm−1 that was assigned to a contribution due to physical adsorption of the molecule. Another peak found at 2362cm−1 evidenced that this molecule interacts with the Cu2+, which appears to act as an electron accepting Lewis acid site. The aim of the present paper is to report a Pnma stable Cu-nitroprusside polymorph obtained by the precipitation method that can adsorb carbon dioxide.

A thorough structural characterization of the synthesized Ni-, Zn-, and Cd-nitroprussides (NPs) with X-ray diffraction (XRD), thermogravimetric analysis, diffuse reflectance infrared Fourier transf...

The synthesis and properties of Ag-doped ZnO thin films and junctions grown by pulsed-laser deposition are examined. Hall measurements indicate that silver-doped ZnO films can be p-type when deposited at relatively low temperature with hole concentrations on the order of 10(19) cm(-3). Photoluminescence reveals a near-bandedge emission at room temperature with little or no visible emission due to midgap states. The properties of Ag-doped ZnO/Ga-doped ZnO thin-film junctions deposited on c-plane sapphire were also examined. Current-voltage measurements across the junction showed rectifying behavior with a turn-on voltage of 3.0 V. Light emission was detected for junctions under bias.

The synthesis and properties of Ag-doped ZnO thin films and junctions grown by pulsed-laser deposition are examined. Hall measurements indicate that silver-doped ZnO films can be p-type when deposited at relatively low temperature with hole concentrations on the order of 10 19 cm -3 . Photoluminescence reveals a near-bandedge emission at room temperature with little or no visible emission due to midgap states. The properties of Ag-doped ZnO/Ga-doped ZnO thin-film junctions deposited on c-plane sapphire were also examined. Current-voltage measurements across the junction showed rectifying behavior with a turn-on voltage of 3.0 V. Light emission was detected for junctions under bias.

Coating silicon dioxide on hydrothermally grown ZnO nanorods is demonstrated using a low temperature plasma enhanced chemical vapor deposition (PECVD) system. Wurtzite structured ZnO nanorods were prepared by spin coating ZnO nanocrystals onto plastics or glass substrates. Then, the nanorods were subsequently grown in a zinc nitrate solution. SiO2 was deposited by PECVD at 50 °C. No current could be measured through the patterned metal dots on the SiO2 coated sample, which indicates that SiO2 was covered seamlessly across the entire substrate. Photoluminescence measurements indicated that the SiO2 layer covering the nanorods did not alter the optical properties of the ZnO.

The dependence of p-type conversion on Mg content in Zn1−xMgxO:P films (x=0.1,0.05) is examined. As-grown Zn0.95Mg0.05O:P films were n type but converted to p type after rapid thermal annealing. p-type Zn1−xMgxO:P films were successfully achieved without post-thermal annealing treatments for a Mg content of x=0.10. Increasing magnesium content in the ZnMgO:P solid solution generally degrades the luminescence properties, suggesting the formation of nonradiative states.

The effects of buffer layer deposition conditions on subsequent ZnO epitaxy on sapphire (0001) were examined. An initial ZnO buffer layer improves surface roughness for a wide range of buffer layer growth temperatures and pressures. Changes in buffer layer growth pressure and temperature have a moderate effect on the roughness of subsequent film growth. However, the conditions for buffer layer deposition have a large impact on crystallinity of subsequent films. In particular, the out-of-plane X-ray diffraction rocking curve full-width half-maximum decreased as buffer deposition temperature or O2/O3 pressure increases. Carrier mobility in the subsequent thick ZnO film was enhanced with increase in buffer layer deposition temperature. Carrier concentration decreased with increasing buffer layer deposition pressure.

The properties of ZnO thin films grown with ozone are examined. Annealing studies were performed on ZnO films grown by pulsed‐laser deposition using either O2 and an O2/O3 gas mixture as the oxidant. The carrier density of ZnO films grown with pure O2 generally decreases upon annealing in 1 atm O2. In contrast, the n‐type carrier density for ZnO films grown with O2/O3 mixture gas increased with O2 annealing. The results indicate that acceptor states, created via growth in ozone, are annihilated with post‐annealing. This suggests that the ozone‐related acceptor states are metastable. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

ZnO-based light emitting diodes were fabricated on c-plane sapphire using ZnO:P∕Zn0.9Mg0.1O∕ZnO∕Zn0.9Mg0.1O∕ZnO:Ga p-i-n heterostructures. The p-i-n heterojunction diodes are rectifying and show light emission under forward bias. The electroluminescence spectra shows deep level emission at low bias, but near band edge ultraviolet emission at high voltage bias. A decrease in leakage currents in as-fabricated structures was achieved via low temperature oxygen annealing.