XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
158
T1: P–25
Raman studies of Nb- and Cr-doped SrTiO
3
Andrzej Mikuła
1
, Andrzej Koleżyński
1
, and Ewa Drożdż
1
1
Faculty of Materials Science and Ceramics, AGH University of Science and Technology,
30 Mickiewicza Av. 30-059 Krakow, Poland, e-mail: amikula@agh.edu.pl
Strontium titanate (SrTiO
3
) belongs to ABX
3
perovskite group which has attracted many
experimental and theoretical investigations due to outstanding semiconductive properties. Some
of them can be successfully extended/improved by doping with various transition metal atoms,
e.g. niobium or chromium ones. Assuming that both impurities substitute titanium in bulk
structure, doped SrTiO
3
should show n or p type conductivity for Nb- and Cr-doped structures
respectively. In addition to changes in electronic structure and thus electrical properties, doping
bulk structure with one of the mentioned additives influences strongly also structural properties.
In this work we present the results of synthesis and structural characterization of Nb- and Cr-
doped SrTiO
3
. Strontium titanate with different amount of Nb (SrTi
1-x
Nb
x
O
3
, where x=0.01, 0.02
and 0.03) and Cr (SrTi
1-y
Cr
y
O
3
, where y=0.01, 0.02, 0.04 and 0.06) impurities have been
synthesized using modified citrate sol-gel method. After synthesis, materials have been
calcinated (900°C), sintered (1200°C) and structurally characterized by XRD, SEM and Raman
studies supported by theoretical ab initio simulations. It has been shown that doped SrTiO
3
samples are single-phase, chemically homogenous and indicate total porosity of around 50%.
Based on comprehensive, theoretical and experimental Raman studies the bands related to Cr–O
and Nb–O oscillations have been identified and the total influence of these additives on SrTiO
3
spectra have been analyzed and described in detail.
Keywords: Raman spectroscopy; SrTiO
3
; structural characterization; ab initio calculations
Acknowledgment
This work was financially supported by the National Science Center of the Republic of Poland, Grant No
2014/14/E/ST5/00763.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
159
T1: P–26
The influence of chlorination on the vibrational spectra and structure
of metallophthalocyanines
Volodymyr Dzhagan
1
, Dmytro Solonenko
1
, Tobias Rüffer
2
, Torsten Hahn
3
,
Heinrich Lang
2
, Jens Cortus
3
, Georgeta Salvan
1
, and Dietrich R.T. Zahn
1
1
Semiconductor Physics, Technische Universität Chemnitz, Reichenhainer Str. 70, D-09126
Chemnitz, Germany, e-mail: volodymyr.dzhagan@physik.tu-chemnitz.de
2
Institute of Chemistry, Technische Universität Chemnitz, Straße der Nationen 62, D-09126
Chemnitz, Germany
3
Institute of Theoretical Physics, TU Bergakademie Freiberg, Leipziger Str. 23, D-09596 Freiberg,
Germany
Metallophthalocyanines (MePcs) are organic semiconductors which possess optical and
electrical properties of broad scientific and application interest. Owing to their low production
costs as well as high thermal and chemical stability, MePcs as well as their heterojunctions with
other organic and inorganic semiconductors or metals can be utilized for light-emitting diodes,
photovoltaic cells, organic field effect transistors, and sensors [1]. While pristine MePcs exhibit
p-type behaviour due to the doping with electron accepting molecules, thin films of e.g.
ZnPcF
16
, were shown to exhibit n-type behaviour [2]. The peripheral substitution of the
conjugated macrocycle of MePcs by electron-withdrawing or electron-donating groups lowers
the HOMO and LUMO levels (with respect the vacuum level), being a facile way to vary charge
injection barrier, sensitivity, and selectivity towards the different analytes, or other properties of
the functional elements based on MePcFx or MePcClx (x = 4, 8, 16).
Since the vibrational spectroscopy techniques (IR and Raman) are sensitive to minor
changes of the structure and environment at the molecular level, they are particularly useful for
the study of relatively weak binding interactions between MePcs and ligands or chemical
analytes [3]. At the same time, although the vibrational spectra of H2Pc and a series of MePcs
(CuPc, ZnPc, FePc, CoPc, NiPc, etc.) have been well studied [3, 4], much less reports can be
found about vibrational structure spectra of MePcFx and no studies of their chlorinated
counterparts. In this work, based on our own experimental data and DFT calculations, we
performed a detailed study of the vibrational Raman and IR spectra of a series of MePcCl8-type
MePcs (Me = Mn, Fe, Co, Ni, Cu). The effects of the chlorination on the electronic structure of
the molecules are also discussed, as it is a key factor determining the resonance conditions in the
Raman scattering process.
Keywords: metallophthalocyanines; Raman spectroscopy; infrared spectroscopy
Acknowledgment
This work is supported by the DFG project FOR 1154 “Towards Molecular Spintronics”.
References
[1] C.C. Leznoff, A.B.P. Leve., Phthalocyanines, Properties and Applications, V. 4; Wiley-VCH, 1996.
[2] S. Hiller, D. Schlettwein, N.R. Armstrong, D. Wöhrle, J. Mater. Chem. 8 (1998) 945.
[3] T.V. Basova, N.S. Mikhaleva, A.K. Hassan, V.G. Kiselev, Sensors Actuators B. 227 (2016) 634.
[4] E. Kol’tsov, T. Basova, P. Semyannikov, I. Igumenov, Mater. Chem. Phys. 86 (2004) 222.
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