Structural phase transition behaviour of ZnaSb3 and its substitutional compounds （Zn0.98M0.02）4Sb3 （M = Al,Ga and In） at low temperatures

Structural phase transitions of Zn4Sb3 and its substitutional compounds (Zn0.98M0.02)4Sb3 (M = Al, Ga and In) are investigated by electrical transport measurement and differential scanning calorimetry below room temperature. The results indicate that both β→α and α→α′ phase transitions of Zn4Sb3 are reversible and exothermic processes, which may be explained as that both the transitions originate from the ordering of the disordered interstitial Zn and vacancies in regular sizes. The derived activation energies of β→α and α→α′ phase transition processes for Zn4Sb3 are E1 = 3.9 eV and E2 = 4.1 eV, respectively. Although no remarkable influence on activation energy E2 is observed after Al doping, Al substitution for Zn causes E1 to increase to 4.6 eV, implying its suppression of βα transition to a great extent. Moreover, it is found that both βα and αα′ transitions are completely prohibited by substitution of either In or Ga for Zn in Zn4Sb3. The underlying mechanisms for these phenomena are discussed.

Structural phase transition behaviour of Zn4Sb3 and its substitutional compounds (Zn1.98M0.02)4Sb3 (M= Al, Ga and In) at low temperatures

Structural phase transitions of Zn₄Sb₃ and its substitutional compounds (Zn_1.98M_0.02)₄Sb₃ (M= Al, Ga and In) are investigated by electrical transport measurement and differential scanning calorimetry below room temperature. The results indicate that both β → α and α → α' phase transitions of Zn₄Sb₃ are reversible and exothermic processes, which may be explained as that both the transitions originate from the ordering of the disordered interstitial Zn and vacancies in regular sizes. The derived activation energies of β → α and α → α' phase transition processes for Zn₄Sb₃ are E₁ =3.9~eV and E₂=4.1~eV, respectively. Although no remarkable influence on activation energy E₂ is observed after Al doping, Al substitution for Zn causes E₁ to increase to 4.6~eV, implying its suppression of β ≤ftrightarrow α transition to a great extent. Moreover, it is found that both β ≤ftrightarrow α and α ≤ftrightarrow α ' transitions are completely prohibited by substitution of either In or Ga for Zn in Zn₄Sb₃. The underlying mechanisms for these phenomena are discussed.