ELFT HÍRADÓ

[Zsolt Kovacs <kovacszs AT metal.elte.hu>]

                     MEGHIVO

       az ELTE TTK Altalanos Fizika Tanszek
                 szeminariumara



            Prof. Ricardo B. Schwarz
     (Los Alamos National Laboratory, USA)

 Thermodynamic Explanation for the Hysteresis
           in Metal-Hydrogen Systems



Helye: ELTE TTK Eszaki Tomb, Altalanos Fizika Tanszek
      1117 Budapest, Pazmany Peter setany 1/A,
      4.emelet 4.70. terem (tanacsterem)

Ideje: 2005. oktober 4. kedd, 8.30.


Absztrakt:

The ubiquitous hysteresis in the pressure-composition isotherms of 
metal-hydrogen systems is indicative of an energy-dissipation 
mechanism.  Often, researchers attribute the hysteresis to the 
generation and annihilation of lattice defects such as dislocations.  We 
demonstrate that the true origin of the hysteresis is the coherency 
strain that must be overcome to create the hydride phase (on charging, 
starting from the metal phase) or to create the metal phase (on 
discharging, starting from the hydride phase).  The coherency strain 
generates a "macroscopic" energy barrier that cannot be surmounted by 
thermal fluctuations.  The theory also predicts that the chemical 
potential for hydrogen within the two-phase metal-hydride phase is a 
linear function of the average hydrogen concentration. 
Data for the Pd-H system is used to evaluate the theory.



Minden erdeklodot szivesen latunk.
A 2005/2006. tanev I. felevi programja megtalalhato a kovetkezo cimen:
http://metal.elte.hu


                              Kovacs Zsolt