(K_(0.5)Na_(0.5))NbO_(3)-(Ca_(0.5)Sm_(0.5))(Mg_(0.5)Nb_(0.5))O_(3)铁电陶瓷的光致介电响应与光致发光

Photodielectric Response and Photoluminescence of(K_(0.5)Na_(0.5))NbO_(3)-(Ca_(0.5)Sm_(0.5))(Mg_(0.5)Nb_(0.5))O_(3)Ferroelectric Ceramics

介电常数在光照下发生改变的特性可用于开发新型光控器件。采用传统固相烧结法制备了不同物质的量比的(1-x)(K_(0.5)Na_(0.5))NbO_(3)-x(Ca_(0.5)Sm_(0.5))(Mg_(0.5)Nb_(0.5))O_(3)(KNN-x CSMN,0.02≤x≤0.06)陶瓷,研究了其结构与光致介电响应行为。引入CSMN组分后,陶瓷的相结构由正交相转变为赝立方相,晶粒尺寸明显减小。在365 nm波长的光照下观察到明显的光致介电响应,并在x=0.03和测试频率为80 Hz时陶瓷具有高达约249%的介电可调率。弥散指数从1.43增加到1.82表明其弛豫行为增强,光学带隙从3.00 eV降低到2.36 eV。在406 nm波长的光激发下陶瓷的光致发射光谱显示出强烈的橙红色发射。同时,在光的开与关状态下其电容值呈现出可逆的开关特性,电容比约为3.5。这些结果有助于探索新型非接触式器件,如光调电容式传感器、光开关。

The change of the dielectric constant under illumination can be used to develop new-type light-controlled devices.(1-x)(K_(0.5)Na_(0.5))NbO_(3)-x(Ca_(0.5)Sm_(0.5))(Mg_(0.5)Nb_(0.5))O_(3)(KNN-x CSMN,0.02≤x≤0.06)ceramics with different molar ratios were prepared by traditional solid-phase sintering method,and the structure and photoelectric response behavior were studied.When CSMN is introduced,the phase structure of ceramics changes from the orthogonal phase to the pseudo-cubic phase,and the grain size decreases significantly.An obvious photodielectric response is observed under the illumination of 365 nm light,and the dielectric tunability is up to about 249%at x=0.03 and a test frequency of 80 Hz.The increase in diffusion coefficient from 1.43 to 1.82 enhances the relaxation behavior of the ceramics,and the band gap decreases from 3.00 eV to 2.36 eV.A strong orange-red light is emitted under the illumination of 406 nm light.Meanwhile,the capacitance shows reversible switching characteristics at light-on and light-off states,and the switching ratio of capacitance at on/off states is about 3.5.These results will help to explore new noncontact devices,such as phototunable capacitive sensors and optical switches.