Lead-free piezoceramics based on alkali niobates

Lead-Free Ferroelectric Ceramics with Perovskite Structure

“…7, the T O-T and T C are clearly observed, the T O-T is close to 200°C as reported in several works (Du et al, 2006;Egerton & Dillon, 1959). The Curie temperature also agrees well with that reported previously which is near to 420°C (Ringgaard & Wurlitzer, 2005;Singh et al, 2001). The dielectric constant and dielectric losses are improved when the sintering temperature is 1060 and 1080°C, but at 1100 and 1120°C the dielectric constant diminishes and tan δ increases, this is directly related with density that depends on the liquid phase formation and vacancies generated when potassium and sodium are lost.…”

Synthesis of advanced ceramics by hydrothermal crystallization and modified related methods

“…These pure and nano-crystalline Li 2 SiO 3 may be suitable to be used for certain applications such as CO 2 absorption [103][104][105]. Today, synthesis of lead-free piezoceramics is of strong interest when looking at a more environmentally friendly option for the fabrication of optical and acoustic devices such as optical wave-guiding and frequency doubling [116][117][118][119][120]. The different studies have been focused on the preparation of sodium-bismuth titanates and potasium-sodiumniobates (KNN) [117,[121][122][123][124].…”

Strain Mechanisms in Lead-Free Ferroelectrics for Actuators

“…[121][122][123][124][125][126][127][128][129][130][131][132][133][134][135][136][137][138][139]258,[275][276][277][278] The KNN-based family of materials is also widely considered as a potential candidate to replace PZT. 10,29,154,279 pm/V at 2 kV/mm. These exceptional properties were achieved through a complex texturing process.…”

“…284,285 The correct choice of reagents is critical since K 2 CO 3 is particularly sensitive to moisture. 279 A controlled atmosphere and humidity of the raw materials prior to calcination, during calcination, and also during sintering should be considered for obtaining the desired stoichiometry. [286][287][288][289] Additional problems arise also during sintering due to an extremely narrow sintering window in terms of temperature and dwelling time [290][291][292] , early activation of surface diffusion that reduces the driving force for densification 273 , and high volatilization of K + above 1000 °C.…”