A K_2-mNb₂O_6-m/2 single crystal with a pyrochlore phase formed when the Nb₂O₅ + x mol% KOH specimens with 0.6 ≤ x ≤ 1.2 were solvothermally heated at 230 °C for 24 h. They have an octahedral shape with a size of 100 μm, and the composition of this single crystal is close to K_1.3Nb₂O_5.65. The single-crystal KNbO₃ formed when the single-crystal K_2-mNb₂O_6-m/2 was annealed at a temperature between 600 °C and 800 °C with K₂CO₃ powders. When annealing was conducted at 600 °C (or with a small amount of K₂CO₃), the KNbO₃ single crystal has a rhombohedral structure that is stable at low temperatures (< − 10 °C). The formation of the rhombohedral KNbO₃ structure can be explained by the presence of the K⁺ vacancies in the specimen. The KNbO₃ single crystal with an orthorhombic structure formed when the K_2-mNb₂O_6-m/2 single crystal was annealed at 800 °C with 20 wt% of K₂CO₃.

将0.6≤x≤1.2的Nb ₂ O ₅  + x mol％KOH标本在230°C溶剂热加热24 h，形成具有烧绿石相的AK _2-m Nb ₂ O _{6-m / 2}单晶。它们具有大小为100μm的八面体形状，并且该单晶的组成接近K _1.3 Nb ₂ O _5.65。单晶的KNbO ₃时形成单晶ķ _2-间的Nb ₂ ö _{6-M / 2}在使用K 600℃和800℃之间的温度下退火₂ CO ₃粉末。当在600°C（或少量K ₂ CO ₃）下进行退火时，KNbO ₃单晶具有在​​低温（<-10°C）下稳定的菱形结构。菱形KNbO ₃结构的形成可以通过样品中K ⁺空位的存在来解释。当将K _2-m Nb ₂ O _{6-m / 2}单晶在800°C和20 wt％的K ₂ CO ₃退火时，形成具有正交晶结构的KNbO ₃单晶。