共查询到20条相似文献,搜索用时 31 毫秒
1.
M. I. Salloum O. S. Grunsky A. A. Shimko A. S. Tver’yanovich Yu. S. Tver’yanovich 《Russian Journal of General Chemistry》2010,80(8):1543-1549
Optical methods of investigation of the defect structures and the composition of lithium niobate (LiNbO3) single crystalsis discussed. The intrinsic defects concentrations in lithium niobate crystals (lithium vacancies (VLi)− and (NbLi)4+ defects, Nb on Li site in the valence state 4+), as a function of the Li/Nb ratio, are also reported. The optical damage
resistance of various lithium niobate samples was investigated as a function of the composition. A remarkable increase in
the optical damage resistance was found in MgO-doped almost stoichiometric lithium niobate crystals. 相似文献
2.
A. N. Novikov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(8):1337-1339
The heat capacity and density of solutions of sodium and potassium perchlorates in N-methylpyrrolidone (MP) at 298.15 K were
studied by calorimetry and densimetry. The standard partial molar heat capacities $
\bar C_{p2}^ \circ
$
\bar C_{p2}^ \circ
and volumes $
\bar V_2^ \circ
$
\bar V_2^ \circ
of NaClO4 and KClO4 in MP were calculated. The standard heat capacities $
\bar C_{pi}^ \circ
$
\bar C_{pi}^ \circ
and volumes $
\bar V_i^ \circ
$
\bar V_i^ \circ
of the perchlorate ion in an MP solution at 298.15 K were determined. The results are discussed with allowance for the specifics
of solvation in the solutions of the salts under study. The coordination number of the ClO4− ion in an MP solution at 298.15 K was calculated. 相似文献
3.
I. E. Animitsa E. N. Dogodaeva E. V. Zabolotskaya 《Russian Journal of Inorganic Chemistry》2010,55(2):254-260
The transport properties of Sr5.66 Cu0.14Nb2.20 O11.30 double perovskite, which enters the homogeneity region of (Sr1-y
Cu
y
)6–2x
Nb2+2x
O11+3x
solid solution, are concerned. The total conductivity is differentiated into terms over wide ranges of temperatures and oxygen
partial pressures $
p_{O_2 }
$
p_{O_2 }
in dry and humid atmospheres. When $
p_{O_2 }
$
p_{O_2 }
is low or high, a test sample has dominant electron transport of n- or p-type, respectively. In air ($
p_{O_2 }
$
p_{O_2 }
= 0.21 atm), the p-type electron conductivity term increases with temperature elevation. In a humid atmosphere ($
p_{H_2 O}
$
p_{H_2 O}
= 0.02 atm), a sample is capable of a reversible incorporation of water occlusion from the gas phase; as a result, some proton
conductivity term appears and ion transference numbers increase over a wide range of $
p_{O_2 }
$
p_{O_2 }
values. 相似文献
4.
A new approximation has been proposed for calculation of the general temperature integral $
\int\limits_0^T {T^m } e^{ - E/RT} dT
$
\int\limits_0^T {T^m } e^{ - E/RT} dT
, which frequently occurs in the nonisothermal kinetic analysis with the dependence of the frequency factor on the temperature
(A=A
0
T
m). It is in the following form:
$
\int\limits_0^T {T^m } e^{ - E/RT} dT = \frac{{RT^{m + 2} }}
{E}e^{ - E/RT} \frac{{0.99954E + (0.044967m + 0.58058)RT}}
{{E + (0.94057m + 2.5400)RT}}
$
\int\limits_0^T {T^m } e^{ - E/RT} dT = \frac{{RT^{m + 2} }}
{E}e^{ - E/RT} \frac{{0.99954E + (0.044967m + 0.58058)RT}}
{{E + (0.94057m + 2.5400)RT}}
相似文献
5.
S. S. Mitić G. Miletić I. D. Rašić A. N. Pavlović 《Journal of Analytical Chemistry》2011,66(1):94-101
A rapid, relatively sensitive and simple kinetic-spectrophotometric method for determining sodium salicylate content has been
developed and validated. This method was based on the Fenton reaction that involved mixing of ferrous ions, hydrogen peroxide
and sodium salicylate in acetic buffer medium. Ferrous ions, oxidized by hydrogen peroxide, formed with salicylate anion purple
complex whose degradation started immediately. This effect was monitored by the decrease of absorbance at 525 nm. The experimental
results showed that the most favorable conditions for complex degradation are: pH = 3.9, $
c_{Fe^{2 + } }
$
c_{Fe^{2 + } }
= 4.7 × 10−5 M, and $
c_{Fe^{2 + } } /c_{H_2 O_2 }
$
c_{Fe^{2 + } } /c_{H_2 O_2 }
= 1/150. The activation energy (E
a) calculated from the slope ($
- \frac{{E_a }}
{{2.303R}}
$
- \frac{{E_a }}
{{2.303R}}
= 2.84 × 103) was 54.3 ± 0.6 kJ/mol. The absorbance increased linearly with the increment of sodium salicylate concentration (r = 0.9983). The system obeyed Beer’s law in a range of 0.93–9.3 μg/mL of sodium salicylate concentration. The calculated values
for the detection limit, according to two formulas, available in the literature, were found to be 0.67 and 0.48 μg/mL. The
variables affecting the rate of the proposed reaction were investigated. The relative standard deviations for five-replicate
determinations of 0.93, 3.31, and 9.30 μg/mL of sodium salicylate were calculated to be 6.80, 2.95, and 1.71%, respectively.
The proposed method has been successfully applied to determining sodium salicylate in human serum and wine and validated by
HPLC (high-pressure liquid chromatography) reference method. 相似文献
6.
Potentiometric method was used to measure the redox potentials of Tm3+/Tm2+ in a eutectic melt of sodium, potassium, and cesium chlorides relative to a chlorine reference electrode in the temperature
range 823–973 K. The main thermodynamic characteristics of the redox reaction TmCl2(solution) + 1/2Cl2(g) ⇆ TmCl3(solution) were calculate from the conditional standard potentials $
E_{{{Tm^{3 + } } \mathord{\left/
{\vphantom {{Tm^{3 + } } {Tm^{2 + } }}} \right.
\kern-\nulldelimiterspace} {Tm^{2 + } }}}^*
$
E_{{{Tm^{3 + } } \mathord{\left/
{\vphantom {{Tm^{3 + } } {Tm^{2 + } }}} \right.
\kern-\nulldelimiterspace} {Tm^{2 + } }}}^*
. 相似文献
7.
The generalized temperature integral $
\int\limits_0^T {T^m } \exp ( - E/RT)dT
$
\int\limits_0^T {T^m } \exp ( - E/RT)dT
frequently occurs in non-isothermal kinetic analysis. Here E is the activation energy, R the universal gas constant and T the absolute temperature. The exponent m arises from the temperature dependence of the pre-exponential factor. This paper has proposed two new approximate formulae
for the generalized temperature integral, which are in the following forms:
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