@Roman Anufriev It is a metal hydride powder. We haven't found the particle size as yet but the sample has been ball-milled.

slam

There  r no. of ways to study the conductivity behaviour of a material. Do dielectric measurements... from that u can calculate  conductivity....or do resistivity versus temperature measurement, that can also help U to know the nature of ur sample.. whether it is semiconductor or insulator... have u done optical studies of ur sample...

Wasalam. @Nazir Ahmad I want to find out thermal conductivity not electrical conductivity.

conductivity itself z a function of temperature. More precisely when one says about conductivity of a material... it is actually the energy required to move the defects in a material ..... as minimum energy z required to move a defect than to create a defect. If U see, single crystals are showing always minimum conductivity then ceramics as number of defects in a crystal are always less than the poly-crystalline material....doing such measurements..u shld be very much familiar about band gap and thermal stability of ur samples.... 

Is it the metal hydride (solid) you need the thermal conductivity for, or is it the ball-milled powder? The measurement method depends on what you search for. In the case of metal hydride powder the effective thermal conductivity is influenced by both the solid phase conductivity and the void (gas or liquid) conductivity, in addition to particle shape, size, size distribution etc) . Actually, the void conductivity has a major impact on the effective (mixture) thermal conductivity, and you should measure the actual solid/void fluid system. (Don't even think of using analogy to electrical conductivity for this case.) If you search for the solid metal hydride thermal conductivity, you need a solid sample (as opposed to powder).

There are numerous ways of performing the measurements for both powders and solid lumps (steady state/'guarded hot plate', transient, laser flash etc), the choice of method depends at large on the sample size and temperature level.

Dear Mahvash

though there are sophisticated modern techniques to measure the heat conduction, the traditional method is to use a setup of plates heated from one side and cooled from the other: One or two reference plates are added on top and on the bottom side, and temperatures in all contact areas are carefully measured ... This technique is reliable as long as the heat conduction of the material is not too extreme (low or high). Its necessary to carefully control heat losses or "temperature jumps" in the contact zones. 

Have a look to the book page I enclose (unfortunatly it is written in German, but I don't have another ready at my hand).  You'll get the figures, in particular fig. 4.45. This assembly is not too difficult to be built and it provides reasonable results, if  you put the plates into an isolated wodden box.

Regards

Nikolaus 

Il faut connaitre sous qu'elle forme est votre matériau (solide, poudre ....).

@Nikolaus Hannoschock  Thanks for the answer. This is the guarded hot plate method, I think. Is there something that I could use for a powdered sample? 

Article: Thermal properties measurement of dry bulk materials with a cylindrical three layers device Y Jannot · A Degiovanni

ABSTRACT: This paper presents a new method dedicated to thermal properties (conductivity and diffusivity) measurement of dry bulk materials including powders. The cylindrical three layers experimental device (brass∕bulk material∕stainless steel) and the principle of the measurement method based on a crenel thermal excitation are presented. The one-dimensional modeling of the system is used for a sensitivity analysis and to calculate the standard deviation of the estimation error. Experimental measurements are carried out on three bulk materials: glass beads, cork granules, and expanded polystyrene beads. The estimated thermal properties are compared with the values obtained by other measurement methods. Results are in good agreement with theoretical predictions: both thermal conductivity and diffusivity can be estimated with a good accuracy for low density material like cork granules or expanded polystyrene beads since only thermal diffusivity can be estimated for heavier materials like glass beads. It is finally shown that this method like all transient methods is not suited to the thermal characterization of wet bulk materials.

Sep 2013 · The Review of scientific instruments

On peut également utiliser un montage identique (2 parois cylindrique) en régime permanent en chauffant par effet joule le cylindre central. Vous pouvez contacter

Yves Jannot au LEMTA à Nancy France

@Alain Degiovanni Thanks

I can suggest you to use the transient hot disk method that works for solids, powder and liquid materials. But, as it was already said, the thermal conductivity will depend on the porosity, pore size, measurement temperature and on the air/liquid present on the "mixture".  So, this technique (as any other) gives you the real values for solid state materials and for mixtures (air plus powder/liquid plus powder / liquids plus liquids ).

Please refer this article

Measurement Techniques for Thermal Conductivity and Interfacial Thermal

Conductance of Bulk and Thin Film Materials