Ionic Conductivity of KTiOPO 4 Single Crystals Grown by Flux Crystallization under Different Conditions

The ionic conductivity of three KTiOPO4 crystals grown from high-temperature solution–melts in combination with the Czochralski technique under different conditions has been investigated. The first crystal was obtained at a cooling rate Vg = 0.2–0.5 mm/day and a ratio of potassium and phosphorus concentrations in the solution–melt [K]/[P] = 2. The other two crystals were grown at a much higher velocity (Vg = 3–7 mm/day) from solution–melts with [K]/[P] = 1.5 and 1. It is shown that the crystal grown upon slow cooling at [K]/[P] = 2 has the lowest ionic conductivity: σ||c = 1.0 × 10–5 and 3 × 10–11 S/cm at 573 and 293 K, respectively.