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Chemical indexing in Inspec

A controlled indexing system for inorganic substances and material systems and is designed to overcome a number of problems which arise in searching for chemical substances in uncontrolled index terms.

Controlled indexing 

Typical search problems

  • Non-stoichiometric compounds or alloys which may be represented in several ways, e.g., GaAIAs or GaxAl1-xAs
  • Chemical formulae that have the same spellings as common English words, e.g., GaP
  • Some chemicals have the same letters and are differentiated by the use of upper and lower case, e.g., Co (cobalt) or CO (carbon monoxide).

Role indicators

Each chemical index term has a role indicator assigned to it to distinguish between the different references.

These are:

  • el for element - e.g., Si
  • bin for binary (two components) - e.g., GaAs
  • ss for system (three or more components) - e.g., H2SO4.

Some substances may be assigned one or more special roles which are of significance to solid-state physics and electronics. These are:

  • int – interface system
  • sur – surface or substrate
  • ads – adsorbate
  • dop – dopant.

Each component of a substance is assigned one of these roles - e.g., the element silicon (Si) is indexed as Si/el and silicon dioxide is indexed as Si02/bin Si/bin 0/bin.

Examples of chemical indexing

  • H2SO4                 H2SO4/ss SO4/ss H2/ss O4/ss H/ss S/ss O/ss
  • P doped Si           Si:P/bin Si/bin P/bin Si/el P/el P/dop
  • Cu-Al alloy           CuAl/bin Cu/bin Al/bin
  • Si-Au interface     Si-Au/int Si/int Au/int Si/el Au/el
  • GaAlAs                GaAlAs/ss Ga/ss Al/ss As/ss
  • GaxAl1-xAs            GaAlAs/ss Ga/ss Al/ss As/ss
  • Ga0.25Al0.75As       Ga0.25Al0.75As/ss Ga0.25/ss Al0.75/ss Ga/ss Al/ss As/ss.

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