TY - JOUR
T1 - Cation disorder in Ga1212
AU - Greenwood, Kevin B.
AU - Ko, Donggeun
AU - Vander Griend, Douglas A.
AU - Sarjeant, Gregory M.
AU - Milgram, John W.
AU - Garrity, Elizabeth S.
AU - DeLoach, Deborah I.
AU - Poeppetmeier, Kenneth R.
AU - Salvador, Paul A.
AU - Mason, Thomas O.
PY - 2000/7/24
Y1 - 2000/7/24
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0034709861&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034709861&partnerID=8YFLogxK
U2 - 10.1021/ic0002667
DO - 10.1021/ic0002667
M3 - Article
C2 - 11196879
AN - SCOPUS:0034709861
SN - 0020-1669
VL - 39
SP - 3386
EP - 3391
JO - Inorganic chemistry
JF - Inorganic chemistry
IS - 15
ER -