240
S. Nahirniak et al.
14.2.2.3 I-U Measurements
The study of current-voltage characteristics was carried out by the method described
in [13, 25]. In accordance with obtained results, 0D and 1D tin (IV) oxide
indicate different nature of the curves due to differences in the morphology of
their structures. For zero-dimensional SnO 2 , I-U dependences are nonlinear at all
temperatures, whereas1D SnO 2 is characterized by ohmic current-voltage curves
(Fig. 14.5).
It is known that ohmic behavior of current-voltage dependencies is very important for sensing properties of material because the sensitivity is maximal for ohmic
semiconductors [26]. Therefore, one-dimensional SnO 2 is more promising for usage
in gas sensors.
Calculated resistance values at different voltages are shown in Fig. 14.6. As
can be observed, zero-dimensional and one-dimensional tin (IV) oxide samples
differ not only in the resistance value but also in the nature of its temperature
dependence. For 0D SnO 2 , the value of the electric resistance decreases with
temperature increasing, which is typical for semiconductor materials. While the
temperature dependences of the electric resistance of 1D SnO 2 pass through the
maximum, the highest values of the electric resistance are observed at 373–423 K.
Considering that for conductor materials electric resistance increases with
increasing temperature and the presence of an extremum on the temperature
dependences may indicate a change in the conductivity type of the material, it
can be argued that the presence of a maximum on the temperature dependences of
resistance for 1D SnO 2 sample may be connected with the transition of conductor
properties of this material to semiconductors.
14.2.3 Investigation of Modifier Effect on the Properties of Tin
(IV) Oxide Powders
Doping or modifying of SnO 2 powders with platinum metals improves their thermal
stability, sensitivity, and selectivity [27]. These parameters are very important for
the use of SnO 2 as a sensitive layer in gas sensors. In this paper, an argentum was
chosen as a modifier, due to its approachability and lesser studying. Samples of
zero-dimensional (0D SnO 2 ) and one-dimensional (1D SnO2) tin (IV) oxides were
synthesized by CVD method at 1123 K and afterward modified by argentum with
different mass contents of the modifier [28].
Optical properties of tin (IV) oxide samples were studied using a two-beam
spectrophotometer Specord 210. The optical band gap of synthesized samples
was determined by graphic method using optical density dependencies of the
suspensions of tin (IV) oxide powders in the range of wavelength λ = 200–
400 nm. Obtained absorption spectra of pure and modified samples of 0D and 1D
SnO 2 nanostructures testify that one-dimensional tin (IV) oxide powders absorb
S. Nahirniak et al.
14.2.2.3 I-U Measurements
The study of current-voltage characteristics was carried out by the method described
in [13, 25]. In accordance with obtained results, 0D and 1D tin (IV) oxide
indicate different nature of the curves due to differences in the morphology of
their structures. For zero-dimensional SnO 2 , I-U dependences are nonlinear at all
temperatures, whereas1D SnO 2 is characterized by ohmic current-voltage curves
(Fig. 14.5).
It is known that ohmic behavior of current-voltage dependencies is very important for sensing properties of material because the sensitivity is maximal for ohmic
semiconductors [26]. Therefore, one-dimensional SnO 2 is more promising for usage
in gas sensors.
Calculated resistance values at different voltages are shown in Fig. 14.6. As
can be observed, zero-dimensional and one-dimensional tin (IV) oxide samples
differ not only in the resistance value but also in the nature of its temperature
dependence. For 0D SnO 2 , the value of the electric resistance decreases with
temperature increasing, which is typical for semiconductor materials. While the
temperature dependences of the electric resistance of 1D SnO 2 pass through the
maximum, the highest values of the electric resistance are observed at 373–423 K.
Considering that for conductor materials electric resistance increases with
increasing temperature and the presence of an extremum on the temperature
dependences may indicate a change in the conductivity type of the material, it
can be argued that the presence of a maximum on the temperature dependences of
resistance for 1D SnO 2 sample may be connected with the transition of conductor
properties of this material to semiconductors.
14.2.3 Investigation of Modifier Effect on the Properties of Tin
(IV) Oxide Powders
Doping or modifying of SnO 2 powders with platinum metals improves their thermal
stability, sensitivity, and selectivity [27]. These parameters are very important for
the use of SnO 2 as a sensitive layer in gas sensors. In this paper, an argentum was
chosen as a modifier, due to its approachability and lesser studying. Samples of
zero-dimensional (0D SnO 2 ) and one-dimensional (1D SnO2) tin (IV) oxides were
synthesized by CVD method at 1123 K and afterward modified by argentum with
different mass contents of the modifier [28].
Optical properties of tin (IV) oxide samples were studied using a two-beam
spectrophotometer Specord 210. The optical band gap of synthesized samples
was determined by graphic method using optical density dependencies of the
suspensions of tin (IV) oxide powders in the range of wavelength λ = 200–
400 nm. Obtained absorption spectra of pure and modified samples of 0D and 1D
SnO 2 nanostructures testify that one-dimensional tin (IV) oxide powders absorb