Cation disorder in Ga1212

Kevin B. Greenwood, Donggeun Ko, Douglas A. Vander Griend, Gregory M. Sarjeant, John W. Milgram, Elizabeth S. Garrity, Deborah I. DeLoach, Kenneth Poeppelmeier, Paul A. Salvador, Thomas O Mason

Research output: Contribution to journalArticlepeer-review


Substitution of calcium for strontium in Lnsr(2-x)Ca(x)Cu2GaO7 (Ln = La, Pr, Nd, Gd, Ho, Er, Tm, and Yb) materials at ambient pressure and 975 °C results in complete substitution of calcium for strontium in the lanthanum and praseodymium systems and partial substitution in the other lanthanide systems. The calcium saturation level depends on the size of the Ln cation, and in all cases, a decrease in the lattice parameters with calcium concentration was, observed until a common, lower bound, average A-cation size is reached. Site occupancies from X-ray and neutron diffraction experiments for LnSr(2-x)Ca(x)Cu2GaO7 (x = 0 and x = 2) confirm that the A-cations distribute between the two blocking-layer sites and the active-layer site based on size. A quantitative link between cation distribution and relative site-specific cation enthalpy for calcium, strontium, and lanthanum within the gallate structure is derived. The cation distribution in other similar materials can potentially be modeled.

Original languageEnglish (US)
Pages (from-to)3386-3391
Number of pages6
JournalInorganic chemistry
Issue number15
StatePublished - Jul 24 2000

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry


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