The tetrahedron is the primary structural motif among the p-block elements and determines the architecture of our bio- and geosphere. However, a broad understanding of the configurational inversion of tetrahedral...
We present new mechanism of the charge transport in thin films based on coherent migration of the deformation of the nanoclusters potential, which carries with it an electron. We represent correlation between deformation and charges as the distorton-inverson quasiparticle. This effect is based on the inversion of the potential energy of nanoclusters due to the Jahn-Teller effect in a nanocluster, when charges flow in a network of nanoclusters. The distorton-inverson is quasiparticle are consisted the distorton and electron or hole, this quasiparticle similar an inverson in the Watkins effect. A distorton is quasiparticle which appears itself in the effects of deformation of the potential of the nanocluster with not closed shell. This quasiparticle is similar a defecton in the Watkins effect. We are calculated transmission spectrum and dispersion properties this quasiparticle.
The alloying and magnetic disordering effects on the site occupation, elastic property, and phase stability of Co2
YGa (Y=Cr, V, and Ni) shape memory alloys are systematically investigated by using the first-principles exact muffin-tin orbitals method. It is shown that with increasing the magnetic disordering degree (y), their tetragonal shear elastic constant C' ((C
11 - C
12)/2) of the L21 phase decreases whereas the elastic anisotropy (A) increases, and upon tetragonal distortions the cubic phase gets more and more unstable. Co2CrGa and Co2VGa alloys with y ≥ 0.2 thus can show the martensitic transformation (MT) from L21 to D022 as well as Co2NiGa. In off-stoichiometric alloys, the site preference is controlled by both the alloying and magnetic effects. At the FM state, the excess Ga atom always tends to take the Y sublattice, whereas the excess Co atom favors the Y site when Y=Cr, and the excess Y atom prefers the Co site when Y=Ni. The Ga-deficient Y=V alloys can occur the MT also at the FM state by means of Co or V doping, and the MT temperature (T
) should increase with their addition. In the corresponding FM Y=Cr alloys, nevertheless, with Co or Cr substituting for Ga, the reentrant MT (RMT) from D022 to L21 is promoted and then T
for the RMT should decrease. The alloying effect on the MT of these alloys is finally well explained by means of the Jahn-Teller effect at the paramagnetic (PM) state. At the FM state, it may originate from the competition between the austenite and martensite about their strength of the covalent banding between Co and Ga as well as Y and Ga.