Özkar, Saim
New results are presented concerning the topotactic self-assembly, n-type doping and band-gap engineering of an intrazeolite tungsten(VI) oxide supralattice n(WO3)-Na56Y, where O < n ≤ 32, built-up of single size and shape (WO3)2 dimers. In particular it has been found that the oxygen content of these dimers can be quantitatively adjusted by means of a thermal vacuum induced reversible reductive-elimination oxidative-addition of dioxygen. This provides access to new n(WO3−x)−Na56Y materials (0 < x ≤ 1.0) in which the oxygen content, structural properties and electronic architecture of the dimers are changed. In this way one can precisely control the oxidation state, degree of n-doping and band-filling of a tungsten(VI) oxide supralattice through an approach which can be considered akin to, but distinct in detail to, that found in the Magneli crystallographic shear phases of non-stoichiometric bulk WO3−x. Another discovery concerns the ability to alter local electrostatic fields experienced by the tungsten(VI) oxide moieties housed in the 13Å supercages of 16(WO3)−M56Y, by varying the ionic potential of the constituent supercage M+ cations across the alkali metal series. This method provides the first opportunity to fine-tune the band-gap of a tungsten(VI) oxide supralattice. A miniband electronic description is advanced as a qualitative first attempt to understand the origin of the above effects. The implications of these discoveries are that cluster size, composition and intrinsic electrostatic field effects can be used to “chemically manipulate” (engineer) the doping and band architecture of intrazeolite supralattices of possible interest in quantum electronics and nonlinear optics.


Temperature dependent band gap in SnS2xSe(2-2x) (x=0.5) thin films
Delice, S.; Isik, M.; Gullu, H. H.; Terlemezoglu, M.; Surucu, O. Bayrakli; Hasanlı, Nızamı; Parlak, Mehmet (Elsevier BV, 2020-08-01)
Structural and optical properties of SnS2xSe(2-2x) thin films grown by magnetron sputtering method were investigated for composition of x = 0.5 (SnSSe) in the present study. X-ray diffraction, energy dispersive X-ray spectroscopy, atomic force microscopy and scanning electron microscopy methods were used for structural characterization while temperature-dependent transmission measurements carried out at various temperatures in between 10 and 300 K were accomplished for optical investigations. X-ray diffract...
Thermally stimulated currents in n-InS single crystals
Hasanlı, Nızamı; Yuksek, NS (Elsevier BV, 2003-03-24)
Thermally stimulated current measurements are carried out on as-grown n-InS single crystals in the temperature range of 10-125 K. Experimental evidence is found for four trapping centers present in InS. They are located at 20, 35, 60 and 130 meV. The trap parameters have been determined by various methods of analysis, and they agree well with each other.
Thermoluminescence characterization of (Ga2Se3)(0.25) - (Ga2S3)(0.75) single crystal compounds
Isik, M.; Guler, I; Hasanlı, Nızamı (Elsevier BV, 2020-03-15)
Ga2Se3 and Ga2S3 compounds take attention due to their potential applications in photovoltaics. Defects and impurities may affect the quality of optoelectronic devices. Therefore, it is worthwhile to determine the parameters (activation energy, order of kinetics, frequency factor) of traps associated with the defects and/or impurities. The aim of the present paper is to investigate the trapping parameters of (Ga2Se3)(0.25) - (Ga2S3)(0.75) single crystal which is one of the member of (Ga2Se3)(x) - (Ga2S3)(1-...
Atomic and electronic structure of Bi/GaAs(001)-alpha 2(2x4)
Usanmaz, D.; ÇAKMAK, MELEK; Ellialtıoğlu, Süleyman Şinasi (IOP Publishing, 2008-07-02)
We report an ab initio pseudopotential calculation for the atomic and electronic structure of Bi/GaAs(001)-alpha 2(2 x 4). Three structural models with Bi coverages of Theta = 1/4 are considered, containing one Bi dimer or two Bi-As mixed dimers. According to our calculations for this coverage, the atomic model of the Bi/GaAs(001)-(2 x 4) reconstruction is similar to the alpha 2 structure of the clean GaAs(001)-(2 x 4) surface in which the top As dimer is replaced by a Bi dimer. This result is in agreement ...
Interactions at fiber/matrix interface in short fiber reinforced amorphous thermoplastic composites modified with micro- and nano-fillers
Isitman, Nihat Ali; Aykol, Muratahan; Kaynak, Cevdet (Springer Science and Business Media LLC, 2012-01-01)
This study aims at systematically extracting fiber/matrix interfacial strength in short-glass fiber-reinforced polymer composites using an experimental micromechanics approach which employs mechanical properties and residual fiber length distributions to derive the apparent interfacial shear strength. We started from neat high-impact polystyrene matrix short-glass fiber-reinforced composites (HIPS/GF) with varying fiber loading and proceeded toward HIPS/GF hybrid composites containing micro- and nano-filler...
Citation Formats
G. OZIN et al., “DOPING AND BAND-GAP ENGINEERING OF AN INTRAZEOLITE TUNGSTEN(VI) OXIDE SUPRALATTICE,” 1991, vol. 233, Accessed: 00, 2021. [Online]. Available: