Ultramicroanalysis of Conducting Polymers with Atom-Probe

本研究的目的是阐明导电聚合物聚吡咯(PP)的结构、结合状态和掺杂剂的分布，以及充分利用原子探针(A-P)的独特能力对氧化的影响。对高温超导陶瓷的A-P超微分析的有效性进行了检验。A-P样品是针尖半径小于1000的细针。由于制备尖锐的聚合物针尖并不容易，因此通过电化学聚合吡咯在铂针尖上制备了一层薄的PP薄膜。使PP导电的掺杂剂为ClO_4^-和BF_4^-。A-P质量分析表明，氧原子在PP的C-H键断裂，然后释放H，形成稳定的C=O双键。在空气中暴露3个月后，完全氧化的PP膜的厚度约为500。PP中没有检测到氯原子，可能是由于其较高的蒸汽压所致。相反，具有高熔点的B-O相互作用使高熔点的B离开PP的氧化区，并从未氧化的PP中检测到。Al、Ag或沉积在PP上的薄膜中检测到Al^+、Ag^+、AlO^+和AgO^+，而In与各种氧化PP碎片如In-Co^+、In-C_2O_2^+和In-C_2NO^+一起被检测到。为了解释高T_c陶瓷的超导机理，提出了一个新的模型。在这个模型中，吸附在陶瓷表面的额外氧原子从陶瓷的铜-氧网络中的氧原子中吸取电荷。然后，诱导的网络氧的孤对轨道被电子极化并与传导电子相互作用，产生电子间引力和库珀对，使陶瓷具有超导性能。

The purpose of this study is to clarify the structures and binding states and the distrubution of dopants of the conducting polymer, polypyrrole(PP), and the effect of oxidation fully utilizing the unique capability of the atom-probe(A-P). Usefulness of the ultramicroanalysis of high temperature superconducting ceramics with A-P was examined.A-P specimens are fine needles with a tip radius of less than 1000<ang>. Since it is not easy to make a sharp polymer tip, a thin PP film was fablicated on a Pt tip by electrochemically polymerizing pyrrole. The dopants to make PP conductive are ClO_4^- and BF_4^-. PP-metal interfaces were formed by depositing a metal film in the UHV A-P.The distribution of cluster ions detected by the A-P mass analysis indicates that an oxgen atom breaks in a C-H bond of PP and then release H forming a stable C=O double bond. The thickness of the fully oxidized PP film is approximately 500<ang> after 3 month exposure to air. The Cl atoms dpoed in PP were not detected possibly due to its high vapor pressure. On the contrary, boron with the high melting temperature migrates away from the oxidezed regions of PP by the repulsive B-O interaction and is detected from the non-oxidized PP.Al^+, Ag^+, AlO^+ and AgO^+ were detected from the Al, Ag or In films deposited on PP but In was detected with various oxidized PP fragments, such as In-Co^+, In-C _2O_2^+ and In-C_2 NO^+.In order to explain the superconduction mechanism of high Tc ceramics, a new model has been proposed. In this model, extra oxygen atoms absorbed on the ceramic surface draw electronic charge from the oxygen atoms of the Cu-O network of the ceramics. Then, the induced lone pair orbitals of the network oxygen are electronically polarized and interactwith the conduction electrons and generate the inter-electron attractive force and the Cooper pairs which make the ceramics superconductive.