Anti-site defect

Intrinsic defects (or native or simply defects ) are imperfections in tire crystal itself, such as a vacancy (a missing host atom), a self-interstitial (an extra host atom in an otherwise perfect crystalline environment), an anti-site defect (in an AB compound, tliis means an atom of type A at a B site or vice versa) or any combination of such defects. Extrinsic defects (or impurities) are atoms different from host atoms, trapped in tire crystal. Some impurities are intentionally introduced because tliey provide charge carriers, reduce tlieir lifetime, prevent tire propagation of dislocations or are otlierwise needed or useful, but most impurities and defects are not desired and must be eliminated or at least controlled. 

Gardiner GR, Islam MS (2010) Anti-site defects and ion migration in the LiFeo.5Mno.5PO4 mixed-metal cathode material. Chem Mater 22 1242-1248... 

Although crystallization is one of the best ways of purifying chemical substances, yet no crystal is free of impurities. An impurity atom is either incorporated in a crystal structure as an interstitial, or replaces an atom of the main element at the same site. In the latter case, known as the substitution defect, the valence (oxidation state) of the replacing and replaced atoms can be the same or different, in which case a charge compensation is required. Finally, there are so-caUed anti-site defects for example, in a regular AB structure some of the A atoms occupy the sites properly belonging to B, and vice versa. In this case, the periodicity is perturbed with neither a vacancy, nor an interstitial, nor an impurity being present. 

Figure 1-16. Anti-site defect pair in CuAu intermetallic. From Shriver and Atkins Inorganic Chemistry.

Figure 5.10 Dependence of saturation magnetization (Ms) on anti-site defect concentration, AS of Sr2FeMoOs. Solid line is the linear fit to the data. Dotted/ dashed lines represent expected Ms dependence according to ferrimagnetic exchange (FIM) and superexchange (SE) models. Reprinted with permission from Balcells et al., 2001 [81]. Copyright (2001) American Institute of Physics...

For ABC2 (A = Cu,Ag B = Ba,In C = Se,Te) analysis of conductivity vs. P(02) and of P(02) vs. T data can be understood either if the covalent bonding instead of the ionic bonding exists, or if anti-site defects exist, where cations occupy vacant anion sites. In these materials as well as in CuInS2, P type as well as -type conductivity are observed. The mobile ions are Cu or Ag. 

Badi SP, Wagemaker M, Ellis BL, Singh DP, Borghols WJH, Kan WH, Ryan DH, Mulder FM, Nazar LF (2011) Direct synthesis of nanocrystalline Lio.9oFeP04 observation of phase segregation of anti-site defects on delithiation. J Mater Chem 21 10085-10093... 

In this sechon, first-principles findings on the intrinsic structural, electronic and electrochemical properties of lithium metal borates are presented in a comparative study of three isotopic LiMBOg (M = Mn, Fe and Co) as a case study from Ref. 32. Furthermore, Li diffusion paths, Li diffusivity, and anti-site defects are discussed as the possible causes of the slow kinetics of lithium metal borates. 

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