SU1226239A1 - Apparatus for determining electrophysical properties - Google Patents

Abstract

The invention relates to the field of technical physics and can be used to study the electrophysical properties of oxide materials in gaseous media. The device contains a heater, a housing that is installed inside the heater, an electrochemical pump, thermocouples, a measuring circuit and a sample. In order to simultaneously determine such electrophysical parameters as electrical conductivity and thermo-emf, and to increase the accuracy of determination, the device additionally contains a solid-electrode sensor. The sensor is installed in contact with the sample. The heater is designed so that it provides a region of constant temperatures in its central part and with a temperature gradient along the edges. A discrete displacement mechanism is connected to the housing via an interface and a programmer. The sensor and thermocouples are connected to the meter and interface, and the interface is connected to the electrochemical pump. 1 il.

Description

The invention relates to the field of engineering physics, in particular to experimental physics, and can be used to study the electrophysical properties of various oxide materials in gaseous media with different partial pressure of oxygen, as well as in technological processes associated with the production of various oxide materials with a complex of target properties that are caused by their defective structure.

The aim of the invention is to simultaneously determine the electrical conductivity and thermo-emf and increase the accuracy of the determination.

The device consists of a body made of vacuum-tight high-temperature ceramic pipe 1, from the end parts of which a vacuum-tightly mounted electrochemical solid electrolyte sensor 2 and pump 3, made in the form of vacuum-tight tubes of calcium oxide stabilized zirconia (ZrO + 15% CaO), which are unipolar ionic conductors for oxygen. The difference between the solid electrolyte sensor 2 and the solid electrolyte pump 3 is related to the degree of coating of the tubes with metal porous electrodes. If the sensor has metal porous coatings on the inner and outer sides, they are only dotted on the end of the test tube, then at nano 3, these coatings occupy about 1/3 of the entire surface of the tube.

Investigation sample 4 is fixed on the solid electrolyte sensor 2 fixedly. Two measuring thermocouples 5 are pressed to the end parts of sample 4, whose branches of the same name are potentiometric instruments for measuring thermo-EMF and electrical conductivity. The sample from the material under study 4 is made in the form of a cylinder with a diameter of 6–8 mm and a length of 10–15 mm with metal electrodes applied to the end parts and pressed against thermocouples 5 when sample 4 is attached to the holder for the latter. The housing 1 is connected to the mechanism 6 of discrete movements, which ensures its movement with the test 4 by the sample 4 along the silicon heater 7, consisting of

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coherent silicon wires to set the required temperature gradient along the length of sample 4. All potentiometric leads from solid electrolyte sensor 2 and pump 3, from thermocouple 5 are connected to interface 8, which is filled with standard blocks and is a connecting link between the elements of the device, the measuring device 9 and the programmer 10, to stop the automatic control of the process and regulate the parameters set by the program, and the speed is the accumulator of the necessary primary information The device, which in the processed form is output to the recorder 11. The device allows the determination of the electrophysical properties of oxide materials in two modes: isothermal and isobaric.

In isothermal mode, the device operates as follows.

All process parameters are embedded in the program, maintained and measured automatically when the conditions specified in the program are met. With the speed set in the program, the programmer 10 through the interface 8 performs heating of the silicon heater 7, as well as the sample under study 4, to those that are isothermally controlled in the program. After the experiment temperature of the programmer 10 through interface 8 has been reached by a mechanism 6 of discrete movements, which is connected to housing 1, the sample has to be moved by examining sample 4 inside the isothermal zone of the C1-tithe heater in such a way that the ends of the sample are at the same temperature, the emf of thermocouples 5 are equal. Almost simultaneously, the programmed partial pressure of oxygen inside the vacuum-tight casing 1 is installed. A certain concentration of oxygen in the gas medium (partial pressure of oxygen) is set electrochemically by polarization of the solid-electrolyte pump 3 with direct current and monitored by a solid-electrolyte sensor 2 The hard electrolyte sensor 2 is also regun operative, the potential of which is compared in the programmer 10 with the set Hbff according to the program and due to different

the degree of polarization of the pump 3 is kept constant. When the sample under study is at equilibrium 4 with a gas medium, which is determined by the constant value of a determined value (resistance, thermo-emf) over time, this value and others are entered into the programmer 10 into a certain memory cell via interface 8. Provided that the temperatures at the ends of the sample under study are equal 4, i.e. when the sample is in the isothermal zone of the heater, its resistance and parasitic thermo-emf are not measured, due to the temperature gradient.

After the programmer 10 has stored these values in the memory, the sample is removed from the isothermal zone of heater 7 and the temperatures of the ends of sample 4 differ. The end of the sample, which is in the natural gradient of the heater, is less heated, and the sensor 2 remains in the isothermal zone of the heater. According to the program, the difference is set to the EMF of thermopar 5 at the same average temperature by the movement of the housing 1 by the mechanism of 6 discrete movements. After reaching equilibrium of sample 4 with the gaseous medium, the emf value is fixed due to the temperature gradient along the sample 4. By polarizing the solid electrolyte pump 3, the following programmed emf value of the solid electrolyte sensor is obtained, which corresponds to the new partial pressure of oxygen in the gaseous medium and is automatically maintained until equilibrium is reached sample 4 with a gaseous medium, and (as at the previous value of the partial pressure of oxygen in a gaseous medium) are produced in th measurement. Thus, measurements of electrical conductivity and thermo-emf are made in the programs

the par-ip oxygen pressure interval at given partial pressure points. The results of measurements at various oxygen partial pressures are accumulated in the programmer 10 and after the end of the experiment in the processed form are output to the α-recorder 11.

In the isobaric mode, thermo-EMF and electrical conductivity are determined in a similar way with the only difference that this determination is carried out at different temperatures in the process of heating or cooling test sample 4 with isothermal suspensions at specific temperatures while maintaining a constant partial pressure of oxygen in the gaseous medium.

Claims (1)

Invention Formula A device for determining the electrophysical properties comprising a heater, a housing, an electrochemical pump installed inside the heater, thermocouples, a measuring circuit, and a sample that is fixed rigidly in the housing, so as to be simultaneously determined. electrical conductivity and thermo-emf and higher accuracy of determination; it additionally contains a discrete displacement mechanism and a solid-electrolyte sensor installed in contact with the sample, the heater is made with a constant temperature region in its central part and with a temperature gradient along the edges, and a discrete displacement mechanism It is connected to the housing via the interface and the programmer, the sensor and thermocouples are connected to the measuring device and the interface connected to the electrochemical pump. Thermocouples Editor L, Gratilllo Compiled by S. Postnov Tehred I.Popovich Proofreader A. Tsko Order 2120/38 Circulation 778 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, d. A / 5 n.iiB. ive- "-" ei, --.--. - - - .- - --------- - - --- Production and printing company, Uzhgorod, st. Project, 4