Lead-free ferroelectric materials using alkali metal doped K-series fiber single crystals

点击翻译按钮获取中文摘要

Alkali metal(Na, Rb or Cs) doped KNbO_3 single crystals are grown using an original pulling down method in order to improve their composition change during a crystal growth. The composition change is improved by means of co-doping of small ionic size Na and large ionic size Rb or Cs into KNbO_3.Size of single crystals was 1-2 mm in diameter and 10-20 mm in length.Starting materials of RbCO_3 and CsCO_3 were easy to absorb moisture. When high purity carbonates were used,(KB)_4Nb_6O_17(B : Na, Rb or Cs) crystal part was formed on the crystal surface caused by absorbed moistures. For the crystal growth, better results were obtained when low purity carbonates were used. Impurity of low purity RbCO_3 and CsCO_3 was K and Na by EDX. Thus, a mish metal concept in rare earth elements is possible to apply in these systems.Their electric properties, such as the dielectric constant and the impedance, are changed depending on the doping ions, but almost the same values were obtained as well as KNbO_3.