It has been reported that single crystals could be grown by normal sintering process, without the addition of a seed, in (K,Na)NbO₃ (KNN)-based ceramics. The growth of huge grains (approximately 5–30 mm) is due to the donor effect on abnormal grain growth (AGG) in KNN-based ceramics. In this study, a composition design rule is suggested to obtain the large single crystal without the seed addition in KNN-based ceramics. In addition, it is also identified by the microstructure observation that the huge grains can be due to the donor effect on the abnormal grain growth which is found in perovskite materials. The donor ratio must be designed to be located at the range between 0.7% and 0.9% compared to that of Na⁺ ions, in order to obtain the large single crystals in KNN-based ceramics. This range of the donor ratio is narrower than that in BaTiO₃ (or SrTiO₃) ceramics.

据报道，在（K，Na）NbO ₃（KNN）基陶瓷中，可以通过常规的烧结工艺生长单晶而无需添加晶种。巨大晶粒（约5–30 mm）的生长是由于施主对基于KNN的陶瓷中异常晶粒生长（AGG）的影响。在这项研究中，提出了一种成分设计规则，以在不添加晶种的情况下获得大的单晶。另外，通过显微组织观察还发现，巨大的晶粒可能归因于钙钛矿材料中发现的供体效应对异常晶粒生长的影响。供体比率必须设计为与Na ⁺相比介于0.7％和0.9％之间离子，以便在KNN基陶瓷中获得大的单晶。该供体比的范围比BaTiO ₃（或SrTiO ₃）陶瓷的范围窄。