Characterization of C12A7 thin films deposited by spray pyrolysis

Effect of free oxygen radical anions and free electrons in a Ca12Al14O33 cement structure on its optical, electronic and antibacterial properties

“…Additionally, the absorption spectra of the CAO@1550C sample displayed its two highest absorption peak positions at 2.8 eV and 1.5 eV. The first peak at 2.8 eV presented electrons transitioning from the occupied cage level (an F + -like center level due to a relaxation time) to the framework conduction band (FCB), as previously reported [28,29]. The energy at 2.8 eV was due to the inter-cage transition energy for the free electrons in cavity-cage structure.…”

“…4 shows the XRD patterns of the synthesized CAO@1350C, CAO@1450C and CAO@1550C samples prepared by heating in a carbon crucible by high frequency electromagnetic induction. The XRD results showed that the patterns of the sintered CAO@1350C and CAO@1550C samples matched the JCPDS#09–0413 file as Ca 12 Al 14 O 33 cement phase [28, 29, 30, 31, 32]. These results confirmed the synthesis of a Ca 12 Al 14 O 33 cement phase in the CAO@1350C and CAO@1550C samples.…”

“…The second peak at 1.5 eV displayed an energy level from the F + -like center level to the cage-conduction band (CCB). A second peak energy level was reported in range of 0.4–1.5 eV [28, 29, 30, 31]. This energy level was too large for the empty cage and an electron with less energy to occupy the cage.…”

“…From Figs. 6, 10, and 11, the energy diagram for insulating Ca 12 Al 14 O 33 :2O 2- and conducting Ca 12 Al 14 O 33 :e − cements obtained from both experiments and calculations [28,30,43] is summarized in Fig. 11(d).…”

Effect of Sr Doping on Electrical Transport and Emission of 12CaO·7Al2O3 Electride

“…Key words: C12A7:eelectride; Sr doping; electrical transport; emission performance 12CaO•7Al 2 O 3 (C12A7)是一种具有天然纳米笼 腔结构的化合物 [1] , 呈立方型晶体结构, 每个晶胞 中包含由两个 C12A7 分子形成的 12 个共面连接的 直径约为 0.4 nm 的笼腔, [2][3][4][5] , 因此 笼腔内的 O 2-很容易被与之半径相近的一价负离子 (H -, O -, F -, Cl -)替代形成 C12A7 的各种衍生物 [6][7][8][9][10] 24 Al 28 O 64 ] 4+ :4e -(C12A7:e -)。有研究表明, C12A7:e -具有与碱金属 Cs (2.1 eV)、Rb (2.2 eV)、K (2.3 eV)、 Na (2.8 eV)相当的低逸出功(2.4 eV) [11] , 在 500 ℃以 下的空气气氛中可以稳定存在, 并保持金属电输运 特性, 在 1200 ℃以下惰性气氛中可以稳定工作 [12] , 因此有望成为一种新型阴极材料。 C12A7:e -电子化合物的研究目前还主要集中在 制备方法的探索和性能优化两个方面, 已报道的高 温 CO/CO 2 混合气氛下还原合成 [13] 、在石墨坩埚中 直接还原合成 [14] 以及利用活性金属在高温下还原 合成等 [15][16][17][18][19][20] 方法的制备时间通常在 30 h 以上, 制备 样品的热发射电流密度在 1 A/cm 2 左右 [21] , 因此如 何缩短制备时间并优化发射性能成为该体系有待解 决的课题。 12SrO•7Al 2 O 3 与 C12A7 具有相同的晶体 结构, 且 12SrO•7Al 2 O 3 的晶胞参数(1.232 nm)大于 C12A7 的晶胞参数(1.197 nm) [22] , 如果 Sr 取代 Ca 将增大笼腔的尺寸, 使得笼腔内的 结果作出的能带结构示意图, 在(Ca 1-x Sr x )12A7:e -的 能带结构中, FCB 的位置比 C12A7:e -降低了 0.3 eV, CCB 的宽度较 C12A7:e -有所增加。 本课题组前期计 算得到 C12A7:e -的 CCB 与 FCB 之间的带隙宽度为 1.6 eV [20] , 而(Ca 样品零场发射电流密度 Fig. 7 Calculate J 0 of (Ca 1-x Sr x ) 12A7:epolycrystalline by method of Schottky…”