Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Lumped type parameters
Patent
1995-09-25
1997-08-12
Regan, Maura K.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Lumped type parameters
324724, 324717, 324149, G01R 2714, G01N 2704
Patent
active
056569408
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Teachnical Field
The present invention relates to an apparatus for measuring the surface resistance and electrical resistivity of a homogeneous resistive material at high temperatures.
2. Prior Art
French patent application 92 05448 of May 4 1992 describes a cell for measuring the electrical resistivity at high temperature and is used exclusively for measuring the electrical resistivity of an undeformable, solid, homogeneous sample. This system has two upper and lower blocks facing one another, each matched by a horizontal face equipped with a pair of wires and between which the sample is positioned.
French patent application 92 10635 of Sep. 7 1992 describes an apparatus for measuring the surface resistance and electrical resistivity on fibers and fabrics at high temperatures. Appropriate solely for strip-like materials (fabrics) or fiber or wire-like material, the device consists of positioning the sample to be tested on a ceramic cylinder and surrounding it with four conductive wires able to maintain it level with grooves and measure the same.
Reference is made hereinafter to publications dealing with the subject of electrical resistivity and surface resistance measurement: temperatures" by G. Beddies and W. Bretschneider (Experimentelle Technik der Physik, East Germany, DA 1986, vol. 34, No. 5, pp 375-377); high temperature" by A. M. George and I. K. Gogolakrishnan (Journal of Physics 1975, vol. 8, No. 1, pp 13-16); resistivity measurements" by Sandra and H. Suvinsky (Scientific Instruments, 1975, vol. 46, No. 4);
None of the apparatuses described in the above documents makes it possible to perform surface resistance and electrical resistivity measurements on thin conductive films (which may or may not be deformable) deposited on insulating supports. Thus, the specificity of these apparatuses limits their use to one type of rigid or deformable, homogeneous material.
The invention relates to an apparatus for measuring the surface resistance and electrical resistivity, particularly at a high temperature (e.g. 1250.degree. C.) of samples such as thin films deposited on insulating supports (quartz, ceramic, fabric, etc.), said apparatus being able to operate under a neutral atmosphere and accessorily under air.
DESCRIPTION OF THE INVENTION
The invention relates to an apparatus for measuring the surface resistance and electrical resistivity of a homogeneous, resistive material sample, characterized in that it comprises a measuring cell having a location able to receive said sample, as well as several electrodes in the form of aligned knives, placed on the same side of the sample and guided in an insulating block, whose ends are positioned on the sample, the pressure necessary for establishing good electrical contacts being ensured by gravity by means of a bevelled shim, two first electrodes making it possible to inject a current into the sample to be tested and two second electrodes making it possible to collect a voltage thereon.
Advantageously the measuring cell can be disassembled into two half-shells, two shouldered spindles permitting disassembly.
Advantageously, the electrodes are Invar knives, guided in an insulating block sufficiently thick to ensure a constant spacing. The rear portion of the electrodes is attached to an articulated system constituted by two brackets and an end fitting, shouldered spindles ensuring the mechanical connections. The bevelled shim bears on the end fitting and has a groove for guiding said end fitting, the weight of the shim having been calculated so as to ensure by gravity a good electrical contact between the electrodes and the sample. Electric current supply and voltage sampling leads travelling in a suspension tube are laser welded to said electrodes. This suspension tube, as well as the complete measuring cell, are made from a ceramic material able to withstand high temperatures and which is both mechanically stable and electrically insulating.
In an advantageous embodiment, the measuring cell is placed in a first quartz enclosure, in which it is
REFERENCES:
patent: 4267506 (1981-05-01), Shiell
patent: 4888546 (1989-12-01), Berry et al.
patent: 5138269 (1992-08-01), Deutsch
Plenum Publishing Corporation, Apr. 1990, Industrial Laboratory, vol. 55, No. 10, A translation of Zavodskaya Laboratriya.
Commissariat a l''Energie Atomique
Do Diep
Regan Maura K.
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