Perovskites: “Effective” Temperature and Coordination Dependence of 38 Ionic Radii

Abstract

The lattice parameters of thirty-one temperature dependent and six single temperature Perovskites have been utilized within the “simple” “ideal” Perovskite planar and volume constrained ionic radii structural model to evaluate the “effective” ionic radii values and ionic radii thermal expansion coefficients of: (i) 12-fold coordinated A-site ions, where A is Ag¹⁺, Cs¹⁺, Na¹⁺, K¹⁺, Rb¹⁺, Ba²⁺, Ca²⁺, Eu²⁺, Pb²⁺, Sr²⁺, Ce³⁺, and La³⁺; (ii) 6-fold coordinated B-site ions, where B is Ca²⁺, Mg²⁺, Mn²⁺, Pb²⁺, Al³⁺, Ce⁴⁺, Cr⁴⁺, Hf⁴⁺, Mo⁴⁺, Os⁴⁺, Pb⁴⁺, Pr⁴⁺, Ru⁴⁺, Sn⁴⁺,Tb⁴⁺, Tc⁴⁺, Ti⁴⁺, U⁴⁺, Zr⁴⁺, Nb⁵⁺, Ta⁵⁺, and U⁵⁺; and: (iii) 6-fold coordinated C-site anions, where C is, F¹⁻, H¹⁻, I¹⁻ and O²⁻. The determined “effective” ionic radii values with thermal expansion coefficients are shown to provide fidelity of temperature dependent lattice parameters of at least thirty-one temperature dependent, six single temperature, and, through use of Vegard's Law, twenty-three “simply” mixed solid solution materials.

Keywords:

• Ionic radii; temperature dependent ionic radii
• thermal expansion
• thermal expansion coefficient
• temperature dependent crystal lattice parameters
• structural phase transitions
• Perovskite crystal lattice modeling
• orthonormal ionic radii space