Rb-doped potassium titanyl phosphate for periodic ferroelectric domain inversion

This article reports the dielectric, conductive, and ferroelectric properties of Rb-doped potassium titanyl phosphate (RKTP) crystals, of formula type RbxK1-xTiOPO4, where x=0.0065 or 0.013, both of which are shown to undergo ferroelectric switching at room temperature with coercive fields varying from 2.3 to 2.7 kV/mm. The measured spontaneous polarizations are 0.18(±0.01) and 0.19(±0.01) Cm-2 for RbxK1−xTiOPO4 with x=0.0065 and x=0.013, respectively. The dependence of the conductivity of Rb:KTP on electric-field amplitude at high fields leads to distorted ferroelectric hysteresis loops. As a result of thermal effects and the redistribution of vacancies, the switching times and switching current peaks vary throughout a series of switching processes at a frequency of 20 Hz. The measured switching times range from 2 to 6 ms and are inversely proportional to the peak current densities. The dielectric relaxation of Rb:KTP is found to be further from the Debye response than that of KTP. A correlation effect is seen to play an important role in reducing the ac conductivity of Rb:KTP at low frequencies relative to that of KTP. The results are discussed in the context of obtaining a KTP derivative, which is suitable for periodic patterning by electric field poling at room temperature.