By tuning the A site cation size it is possible to control the degree of octahedral distortion and ultimately structural symmetry in the new perovskite solid solution La Na K TiO , affording a rhombohedral-to-cubic transition as x increases above 0.4. The La and K cations are distributed randomly across the A site leading to significant phonon disorder in cubic La K TiO (Pm m) which produces a phonon-glass with a thermal conductivity of 2.37(12) W m K at 300 K; a reduction of 75% when...
