Solid State Physics ANNUAL REPORT 2005

THERMO POWER OF Kr IMPLANTED MANGANIN- Cu THERMOCOUPLE T. WilczyĔ ska, R. WiĞ niewski, K. Wieteska Institute of Atomic Energy Low electric thermo power of manganin (Cu- junctions were placed into small glass containers insu- Mn_Ni alloy) relative to the copper is an advantage of lated thermally from each other by polystyrene box. The manganin alloy. The aim of this investigation was to hot junction container had suitable electrical heater. check if electric thermo power remains low after im- Temperature of the junctions was measured with mer- plantation with Kr ions. The work described is part of cury micro thermometer or an additional constantan- wide projected concerned with studies on properties of copper thermocouple. manganin implanted with various heavy ions [1]. Our measurements revealed that implantation of The 10P m thick stripe samples of 1 × 75mm were manganin with Kr ions reduces its thermo power rela- implanted with Kr ions in Laboratory of Nuclear Reac- tive to copper by ~50%. Another result of our study is tion at Joint Institute for Nuclear Research, Dubna. A that thermo power of non implanted manganin relative moderation aluminum foil of 11P m thick and 3mm to Cu is a little lower than given in literature. width was used. According to modeling performed with To assess the origin of such significant decrease in TRIM code [2] implantation produced the enhanced thermo EMF after implantation the thermally forced deposition layer near the back side of sample (Fig. 1). electron diffusion in junctions, contact potential and After implantation the samples were annealed for 100h o phonon forced electron drag components of the Seebeck at 130 - 150 C. effect should be discussed.. Since the dose of implanted Kr ions was low even if we suppose that only ¼ of vol- ume of implanted specimen has enhanced ions deposi- tion the number of implantation induced point defects, typically vacancies, my be of order of 10% of total Cu wire number of atoms and should not play an important role in Seebeck phenomenon. Negative sign of thermo manganin foil power means that at the hot junction electrons are mov- ing from copper to the manganin. The drop of thermal power may mean that concentration of electrons in man- ganin increases. In this case the electrical neutrality of the Kr atom in the manganin is improbable and the existence of positively charged Kr ions could be conjec- tured.

References Fig. 1. Junction of manganin-copper thermocouple for im- [1] T. Wilczy Ĕ ska, R. WiĞ niewski, K. Wieteska and plantation research. B. Sá owiĔ ski,Vacuum 78, 515 (2005) [2] V. K. Semina and A.Yu Didyk, private communication To study the thermo EMF of manganin - copper (2003) junction manganin–copper thermocouples were made by soldering the 50 m diameter Cu wire to the back (with enhanced deposition layer) side of stripe. The

72