SU1603276A1 - High-frequency electrochemical cell - Google Patents

Abstract

The invention relates to the field of analytical instrumentation and is intended to study the processes of growth and dissolution of single crystals, mainly as a result of measurements of the impedance (complex resistance) of the electrode-electrolyte boundary in a wide frequency range. The aim of the invention is to expand the range of analyzed objects of the cell. This goal is achieved by the fact that the electrochemical cell containing a vessel with electrolyte, in which the auxiliary and working electrodes are immersed, is additionally equipped with an electrically conductive cup, inside which a measuring circuit and an electric screen having three cavities, two of which are axial and communicating and the third is located coaxially with the first, the second end of the working electrode is placed in the first axial cavity of the screen with access to the second axial cavity, where by means of clamping The device is connected to the common point of the measuring circuit, and the container is pressed to the screen with a lid fixed on the outer surface of the glass and connected to an auxiliary electrode located coaxially with respect to the working electrode, in the third cavity there is an annular magnetic circuit with a winding connected to the current input of the measuring circuit, the potential input of which is connected to an electrically conducting glass. In addition, the clamping device comprises cams covering the second end of the working electrode and a guide tube located in the threaded hole of the second axial cavity of the electrical screen with the possibility of movement and pressing against the cams. 3 il.

Description

The invention relates to electroanalytical instrumentation and is intended to study the nature of electrode processes. Impedance volt-ampere methods.

The aim of the invention is to expand the class of objects under study and increase the information content of measurements.

FIG. 1 shows a high frequency electrochemical cell, a general view; in fig. 2 - pressurizing contact; in fig. 3 - impedance measurement, cells.

The high-frequency electrochemical cell contains a vessel 1 with electrolyte in which the auxiliary electrode 2, the working electrode 3, the container C with the capillary 5, the electrically conducting cup 6, the measuring circuit 7, the electrical screen P containing the internal 9 and the external 10 are immersed. axial cavity and the inner annular cavity 11, located coaxially to the inner axial cavity 9, clamping contact 12, cover 13, magnetic circuit And with the winding 15.

The working electrode 3 is first placed at the end of its container k with a capillary 5 on the electrolyte side. Inside the electrically conductive glass 6, the measuring circuit 7 and the electric screen 8 are electrically insulated from it. The second end of the working electrode 3 is placed into the internal axial cavity 9 of the screen 8 with an output in the external axial cavity 10, where. through clamping contact 12 is connected to. common point (.) of the measuring circuit 7. The container is pressed against the electric screen 8 by a lid 13 connected to the auxiliary electrode 2 located coaxially with respect to the working electrode 3. The lid 13 is fixed to the outer surface of the glass 6 by means of a threaded connection. In the inner annular cavity 11 there is an annular magnetic circuit U with a winding 15 connected to the current input (T) of the measuring circuit 7, the potential input (P) of which is connected to the electrically conductive cup 6.

The clamping -contact 12 (Fig. 2) contains the cams 16 covering the second end of the working electrode 3 and a forward tube 17 located in the screw hole of the outer axial cavity of the screen 8 with the possibility of rotational displacement and pressing to the cams 16. Inside nap,

the connecting tube 17 is located a rod 18 attached to the second end of the working electrode 3.

Before measurements are made, the cell is prepared for operation. To do this, prefix.io, sn in the lid 13, place the container / 4 with the working electrode 3 and the attached

20

25

thirty

35

40

45

50

55

ten

15

0

five

0

five

0

five

0

A rod 18 is connected to it. The rod 18 and the second end of the working electrode 3 are passed into the internal axial cavity 9 of the screen 8 through the cams 16 located in the external axial cavity 10 into the guide tube 17. Then the cover 13 with the auxiliary electrode 2 fixed on it is screwed on the cup 6, which is fixed in the vessel 1. As a result, a pressure is created in the free space between the auxiliary electrode 2 and the container k, which promotes the filling of the capillary 5 with electrolyte. So that in the capillary 5, having a length of about 2 mm and a diameter of the order of 0.15 mm, air bubbles remain, the free end of the rod 18 extended from the guide tube 17 is given a reciprocating movement of the working electrode 3. Having made sure that the bubbles there is no air, the guide tube 17 is screwed in, pressing the cams 1b of the clamping contact 12 to the working electrode 3 and the screen 8, thus creating a reliable electrical contact between the working electrode 3 and the screen 8. After that, the working 3 and the auxiliary 2 electrodes connect They are connected to a circuit consisting of consistently connected sources of harmonic (frequency 50 Hz) and constant voltage, and a single crystal free of dislocations is grown in the capillary 5. Then the impedance-current-voltage characteristics of the cell between the auxiliary 3 and the working 2 electrodes are measured. These measurements are used to determine the nature of the electrode processes.

The electrochemical cell contains a vessel 1 with electrolyte in which worker 3 and auxiliary 2 electrodes are immersed. The working electrode 3 with the rod 18 attached to it is passed through the ring magnetic circuit 14 and connected via clamping contact 12 to the common point of the measuring circuit 7. An external harmonic oscillator 19 is connected to the electrically conducting glass 6 connected to the auxiliary electrode 2 and the common point . The input of the high-frequency voltage meter 20 is connected between the auxiliary. 2 and about the common point of the measuring circuit 7. High-frequency input

 sixteen

current meter 21 is connected to winding 15 of magnetic circuit 1A.

The measurement of the impedance of the cell area between the auxiliary and working electors is performed as follows.

The voltage of the harmonic oscillator 19 is applied between the auxiliary electrode 2 and the common point of the measuring circuit. The current flowing through the working electrode is equal to

 R Current

Uh I

IP is sensed by the winding 15 of the magnetic circuit C connected to the input of a high-frequency current meter 21, which forms at its output a signal

Kj-f fUi / .e-- / Ui /, (1)

UT K

where K j. - conversion factor

IP current to voltage; is the phase shift of the vector U ... Received in the vector IJj for the beginning of the phase reference of the vectors, we have,. 0. Voltage removed from the auxiliary electrode 2 — working electrode 3 — a common point of 0, is sensed by a high-frequency voltage meter 20, which forms a voltage at the output

Up, K

go

Je;

(2)

TO

20

transmission coefficient of node 20,

(phase shift of the voltage vector and relative to the voltage vector of the DW.

and and described by

Stress

expressions (1) and (2) are used further to determine the components of the impedance Z. For example, to determine (7, (and the phase angle Cpjj of the impedance)

 .. / uJ

Kg

one,/. IV, g to

where K is const-.

q) is the phase shift between the components of the impedance Zj, which for q) O is equal to (.. |

To eliminate the effect of the impedance of the auxiliary electrode 2 on the measurement results Z /, it is over the top

five

0

five

0

The efficiency is chosen on several orders of the larger surface of the working electrode.

Compared with the proGotype, the proposed high-frequency electrochemical cell allows to classify the class of electrochemical objects under study and to increase the information content of the nature of the processes occurring in them due to the possibility of measuring the impedance volt-ampere characteristics directly at the monocrystalline electrode-electrolyte boundary. In addition, the proposed electrochemical cell can also be used to study the properties of the polycrystalline electrode-electrolyte interface. In the latter case, the diameter of the capillary must correspond to the diameter of the working electrode.

Formulas

the invention

A high-frequency electrochemical cell containing a vessel, an electrically conducting glass fixed in it, inside of which an electrical measuring circuit is electrically isolated from it, connected by its potential input to an electrically conducting glass, the common point with a magnetic screen, and the current input to a coil wound on an annular magnetic core placed in the inner annular cavity of the magnetic screen formed by the inner surface of the screen walls and a bokbvoy surface of the axial rod of the screen, slave Chii electrode, an electrically conductive cover; an axial hole fixed on the outer surface of the cup and having an axial hole at the bottom that coaxially an auxiliary electrode is fixed on the outer surface of the lid, so that, in order to expand the class of objects under study and increase the informativity of the measurements, the magnet screen contains an additional external and internal axial communicating cavities, the last of which is located inside the axial shaft of the screen rod, in this cavity is a working electrode, placed its first end in the electrically insulated ny container provided at its bottom portion capillary, the container rests on the cover and placed in the axial hole, a second end attached to the working electrode

the rod is passed to the external axial cavity of the screen, where it is electrically connected to the screen by means of a clamping contact containing cams covering the second end of the working electrode and a guide tube located in the threaded hole of the external axial cavity of the screen press against the cams.

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FIG. 2

L.

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Claims (1)

Claim High frequency electrochemical 35 cell, containing a vessel, an electrically conductive cup fixed in it, inside of which is located an electrical measuring circuit electrically insulated from it, connected by its 40 potential input with a conductive cup, a common point with a magnetic screen, and a current input with a coil wound around a ring. a magnetic core placed in the inner annular cavity of the magnetic screen formed by the inner surface of the walls of the screen and the lateral surface of the axial shaft of the screen, a working electrode, an electrically conductive cover 50; fixed on the outer surface of the glass and having an axial hole in the bottom part, coaxially to which on the outer surface of the lid an auxiliary electrode 55 is fixed, characterized in that, in order to expand the class of objects under study and increase the information content of measurements, the _i magnetic screen contains an additional 16OZ276 but the external and internal axial communicating cavities, the last of which is located inside the axial shaft of the screen, contain a working electrode in this cavity, placed with its first end in an insulating container equipped with a capillary in its bottom, the container rests on the lid and is placed in its axial hole , the second end of the working electrode with the rod attached to it is passed into the external axial cavity of the screen, where it is electrically connected to the screen by means of a clamping contact containing cams, digits together with the second end of the working electrode, and a guide tube disposed in a threaded hole of the outer axial cavity ekIQ wound, with a rotary translational movement to the cams and preload. FIG. 2. i603276 0 // l 3