{"id":27110,"date":"2024-07-22T10:17:01","date_gmt":"2024-07-22T08:17:01","guid":{"rendered":"https:\/\/www.linseis.com\/messgeraete\/electrical-property\/lsr-3\/"},"modified":"2026-02-04T11:25:16","modified_gmt":"2026-02-04T10:25:16","slug":"lsr-l31","status":"publish","type":"messgeraete","link":"https:\/\/www.linseis.com\/en\/instruments\/lsr-thermoelectrics\/lsr-l31\/","title":{"rendered":"LSR-3 (LSR L31)"},"content":{"rendered":"\t\t
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\n\t\t\t\t\t\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\tGet a quote<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Description<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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To the point<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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The Linseis LSR platform<\/strong> can be used to characterize thermoelectric materials almost completely, both in the form of solid materials and thin films.
In the basic LSR-3 (LSR L31) version, both the Seebeck coefficient<\/strong><\/a> and the electrical conductivity<\/strong><\/a> (electrical resistance) of solid materials can be measured fully automatically and simultaneously up to a maximum temperature of 1500\u00b0C.<\/p>

The basic version can be combined with various options to extend the range of applications.
For example, the low temperature option<\/strong> allows fully automatic measurement using LN2<\/sub> cooling down to -100\u00b0C and the use of a special thin film adapter for measuring films<\/strong> and thin layers<\/strong>.<\/p>

An optional camera<\/strong> allows the determination of electrical conductivity with the highest accuracy and the use of the high-resistance option <\/strong>significantly extends the measuring range in order to characterize samples with poor electrical conductivity.<\/p><\/div><\/div>

As the thermal conductivity is required in addition to the Seebeck coefficient and the electrical conductivity in order to calculate the dimensionless figure of merit ZT<\/em><\/b><\/a><\/strong>, it is usually necessary to use another measuring device, such as a LaserFlash<\/b><\/a>, to determine it.<\/p>

To solve this problem, either an additional LaserFlash<\/strong> can be integrated<\/strong> into the Linseis LSR platform (see LZT meter<\/b><\/a>) or a special adapter can be used, which allows the measurement of solid materials using the Harman method<\/strong><\/a>.
This is a direct ZT determination which, in combination with the two original measurements, allows conclusions to be drawn about the thermal conductivity<\/strong><\/a>.
An LSR platform with integrated Harman method is referred to as LSR-3 upgrade<\/strong>\u00a0due to its significant added value.

<\/p><\/div><\/div><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Principle of Seebeck-Coefficient measurement<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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A cylindrical, square or rectangular sample is positioned vertically between two electrodes.
The lower electrode block and optionally also the upper electrode block (to invert the temperature gradient) contain a heating coil (secondary heater).
The entire measuring arrangement is located in an oven, which heats the sample to a specific temperature for the measurement.
When this temperature is reached, the secondary heater in the lower electrode generates a predefined temperature gradient along the sample.
Two laterally contacting thermocouples T1 and T2 now measure the temperature difference (\u0394T = T2 – T1) between the hot and cold contact on the sample.
In addition, one of the two thermocouple leads is used to measure the electromotive force dE (or thermoelectric voltage Vth<\/sub>).<\/p><\/div><\/div>

A unique spring mechanism enables the best possible electrical contact between the thermocouples and the probe and therefore highly accurate measurements.
The Seebeck coefficient can then be easily calculated from the measurement data obtained using the following formula:<\/p><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Measuring principle electrical conductivity<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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A DC four-wire measurement is used to determine the specific electrical resistance or electrical conductivity of the samples.
This allows parasitic influences such as contact or wire resistance to be suppressed and measurement accuracy to be significantly increased.<\/p>

For the measurement in thermal equilibrium (\u0394T = 0K), a constant direct current (IDC<\/sub>) is impressed into the sample using the two electrodes.
Due to the electrodes and sample dimensions, an almost ideal one-dimensional current flow within the sample can be assumed.
The resulting voltage drop (V\u03a9<\/sub>) over a section of the length “t” of the sample is measured again using one of the two thermocouple wires.<\/p><\/div><\/div>

The specific resistance and electrical conductivity can be calculated using the following formulas based on the measurement data and the thermocouple spacing “t”.<\/p><\/div><\/div>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Principle of a Harman measurement<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The Harman method makes it possible to calculate the thermoelectric figure of merit ZT<\/em> of a material from the measurement of the temporal voltage curve of a sample when direct current (DC) is applied.<\/p>\n

For the measurement, a current is impressed into a thermoelectric sample via two needle contacts.
\nDue to the Peltier effect, one of the two junctions is heated or cooled locally.
\nAs a result, the adiabatic boundary conditions produce a characteristic temperature profile over the sample.
\nIf the ratio is formed from the measurement of the initial voltage drop (ohmic part without temperature gradient) and the measurement of the stationary voltage drop (including thermoelectric voltage), the dimensionless figure of merit ZT<\/em> (and from this also the thermal conductivity lambda) can be calculated. <\/p>\n

The fundamental advantages of the Harman method compared to calculating ZT<\/em> from individual measurements are that only a single measuring device is required, only a single sample needs to be prepared and the resulting measurement error for ZT<\/em> is significantly smaller due to the direct measurement.
\nThe disadvantage, however, is that the measurement method can only be used for good thermoelectric materials and up to a maximum of 400\u00b0C. <\/p>\n<\/div>\n<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Adapter for thin films and foils<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Due to their unique properties compared to solid materials, interest in nanostructured samples, such as thin films or nanowires, has increased significantly in recent years.
\nTo meet the requirements of today’s research, LINSEIS has developed two different sample holders for free-standing films and foils or coatings on a substrate for the LSR platform.
\nThanks to the unique design of the sample holders, a variety of differently prepared samples can be characterized with the LSR in terms of coating thickness and manufacturing method. <\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Available accessories<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Sample holder for disk shaped samples<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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\n\t\t\t\t\t\t\t\t\tVarious sample geometries can be measured with the LSR platform: cylindrical (up to \u00f8 6 mm x 23 mm height), rod-shaped (base area up to 5 mm x 5 mm and 23 mm height) or disk-shaped (10 mm, 12.7 mm or 25.4 mm) samples.\nIdeally, the base area of the samples should be smaller than or equal to the surface area of the electrodes to ensure a one-dimensional heat and current flow through the sample.\nTwo sample holders are available for the measurement.\nAlthough cylindrical and rod-shaped legs are the typical configuration in thermoelectric generators (TEG), disk-shaped samples are often required for thermal conductivity measurements in laser or light flash systems.\nIn order to save cumbersome sample preparation steps and eliminate potential sources of error from the outset, the same disk-shaped samples can also be used to measure the Seebeck coefficient and electrical conductivity in the LSR platform thanks to a specially developed sample holder. \t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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\"\"<\/p>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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Thermoelements and Camera-Option<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Standard thermocouples: <\/strong>for maximum precision<\/p>

Jacketed thermocouples: <\/strong>for demanding samples<\/p>

Type K\/S\/C thermocouples: <\/strong><\/p>