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

采用原始拉下法生长碱金属（Na， Rb或Cs）掺杂的KNbO_3单晶，以改善其在晶体生长过程中的组成变化。通过在KNbO_3中共掺杂小离子尺寸Na和大离子尺寸Rb或Cs，改善了KNbO_3的组成变化。单晶直径1 ~ 2mm，长度10 ~ 20mm。RbCO_3和CsCO_3的起始原料容易吸湿。当使用高纯碳酸盐时，由于吸收水分在晶体表面形成（KB）_4Nb_6O_17（B: Na， Rb或Cs）晶体部分。在晶体生长方面，采用低纯度碳酸盐生长效果较好。EDX法测定低纯度RbCO_3和CsCO_3的杂质为K和Na。因此，稀土元素中的弱金属概念有可能应用于这些系统。它们的介电常数和阻抗等电性能随掺杂离子的不同而变化，但与KNbO_3几乎相同。

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.