1. Title of the invention

Manufacture of micro-rods of bismuth and antimony metals for making of thermoelectric devices

2. Applicant

Name : Eesavyasa Technologies Pvt. Ltd.

Nationality : Indian

Address : 108-B, I.D.A. Khanapuram, Khammam(DT), Andhra Pradesh. Pin: 507002

3. Preamble to the description:

Complete specification:

Summary:

In the summary of invention, each important salient feature is explained as follows:

1. In this method of invention, in first stage bismuth metal below its melting point is fused and doped with tellurium microparticles. Similarly antimony metal is also fused to below its melting point and doped with gallium metal.

2. Methods for the doping of tellurium and gallium metals into bismuth and antimony by continuous ball milling in controlled environment or sputtered diffusion of both molten liquid metal solutions taken in same chamber can be employed.

3. After producing doped metals, their fused metal solutions are obtained for both bismuth and antimony metals, they are subjected to pass through either graphite microgrid chamber or special micro extrusion dye for making the micro rods.

4. The both ends of micro rods produced are shaped either in conical or in flattened shapes to facilitate further joining with each other with the help of graphite welding so that thermoelectric junction can be produced

4. Description

In this method of invention, techniques like sintering, sputter diffusion, evaporative vapour diffusion method or electron beam oriented laser ablation can be employed to synthesize micro rods of bismuth and antimony. In the present invention, bismuth and antimony metals are taken in separate crucibles and are sintered or sputtered with required dopant metals like tellurium and gallium respectively in their evacuated chambers separately. In this step doping is possible by controlling the parameters inside the vessels.

Doping of these required metals is possible by continuous ball milling of mixture of bismuth or antimony metals taken in kilograms along with dopant metals likes tellurium and gallium respectively in micrograms in a ball mill under oxygen free atmosphere. Size reduction is obtained by continuous ball milling for several hours to achieve doping. After producing doped bismuth and doped antimony materials separately, they are fused to below their melting points with the help of external induction heating by taking in a heat resistant crucible container separately. Their molten state of liquids will be passed through a graphite microgrid with the help of vacuum suction or by passing through special type of micro extrusion dyes to produce micro rods of bismuth and antimony. These micro rods ends are specially designed to have conical shape or flat surfaces depending on user requirement to undergo graphite welding. This technique is employed to produce low cost thermoelectric devices made up of bismuth and antimony as an alternative for semiconductor peltier chips.

The size of micro rods can be increased and any length of modules can be produced as the basic tendency of metallic bismuth and antimony are not being abused.

Background of invention

The present era of thermoelectric modules are produced by sputter diffusion of p-type and n-type bismuth telluride, p-type and n-type of lead telluride, and other types of mixtures to produce hot and cold junction surfaces at both ends, which are capable of giving thermoelectric peltier effect. But synthesis of these modules require utmost controlled environment and very expensive machines like thin film layer sputtering chambers, molecular evaporative deposition chambers, etc. The total environment is filled with hazardous toxic bismuth telluride fumes.

The concept of the invention is to completely avoid such hazardous semiconductor material usage and to prevent ozone layer depletion by providing an alternative method where natural elementary status of bismuth and antimony metals are used. The production of micro rods or their thin film layer depositions are easy methods and cost effective.

5. Claims

1. We claim that the synthesis of tellurium doped bismuth and gallium doped antimony are first of kinds which impart semiconductor type of properties into basic metals.

2. We claim that in this method of invention for doping of metals continuous ball milling is used under controlled environment which is a novel method that can be applied for doping of any metals or compounds into other materials in similar fashion.

3. We claim that micro rods of bismuth and antimony are produced by passing of their fused solutions through graphite micro grid or sieving plates in separate chambers. This method can be applied for production of any type of micro material production using such grid.

4. We claim that in this method fused metallic solutions or any such kind of fused material passed through specially designed extrusion dyes is used for synthesis of micro rods. By extending this technique if nano extrusion dyes are synthesized, nano particles of any material can be produced and any length of their ingots can be produced.

5. We claim that with this invention as described in claim number 1, the basic raw materials that are required for production of thermoelectric devices without semiconductor peltier chips can be produced.

6. We claim that using these micro rods as described in claim number 1, described thermoelectric modular applications wherever chilling, cooling, refrigeration, cryogenic cooling or selective heat absorbing systems in electronics and other areas can be made

7. We claim that using these micro rods as described in claim number 1, different sizes of power generating batteries, electricity accumulators, power plants can be produced.