A CORRELATION BETWEEN THE STRUCTURAL RELAXATION AND THE ELECTRICAL CONDUCTIVITY OF SEMICONDUCTING VANADATE GLASSES

半导体钒酸盐玻璃结构弛豫与电导率的相关性

• 批准号: 08640743
• 负责人: NISHIDA Tetsuaki
• 金额: $ 1.22万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08640743/
• 关键词: semiconducting glass; structural relaxation; crystallization; electrical conductivity; cleavage of chemical bonds; Mossbauer spectroscopy; DTA; magnetic susceptibility; 電子ホッピング; メスバウアー効果

Heat treatment of glass causes a structural change from glass to glass-ceramics, in which several crystalline particles with 'nanometer size' are precipitated. This structural change, I.e., crystallization of glass, brings about a drastic change of electrical conductivity, magnetism, optical transparency, etc. The present study was carried out in order to elucidate the mechanism of crystallization and the correlation between the structure and physical prperties of glass-ceramics by means of Mossbauer effect, FT-IR,magnetic susceptibility, XRD,and DTA.As a result, following conclusions could be obtained :1) Heat treatment of semiconducting 25K_2O・65V_2O_5・10Fe_2O_3 glass at around the crystallization temperature (Tc) for a short time (10-30 min) results in a jump of the electrical conductivity from the order of 10^<-8> S・cm^<-1> to the order of 10^<-4> S・cm^<-1>, owing to the structural relaxation. After a prolonged heat treatment, the electrical conductivity decreases owing to the prec … More ipitation of an insulating crystalline phase.2) Heat treatment of IR-transmitting aluminate glasses, 60CaO・27Al_2O_3・13Fe_2O_3 and 60CaO・10BaO・17Al_2O_3・13Fe_2O_3, at around the Tc causes a decrease in the IR-transmittance and that of magnetic susceptibility owing to the precipitation of 'nanoparticles' of antiferromagnetic Ca_2Fe_2O_5.3) Activation energy (Ea) required for the crystallization is equal to the bond energies of the structural units (e.g., Ca-O and Al-O bonds), indicating that cleavage of the chemical bonds triggers the crystallization. The value of Ea is reduced to 2.6 eV in the case of vanadate and tungstate glsses containing iron (Fe (III), being equal to the Fe-O bond energy.4) Glass transition temperature (Tg) is in proportion to the magnitude of quadrupole splitting (DELTA), one of the Mossbauer parameters, as discovered by Nishida et a1. ("Tg-DELTA rule", 1990). Heat treatment of silicate glass at around the Tg results in a concordant decrease of Tg with the DELTA of Fe (IlI), owing to the structural relaxation associated with a decrease in the distortion of SiO_4 and FeO_4 tetrahedra.5) The " Tg-DELTA rule", originally discovered for several inorganic glasses containing several mol% of Fe_2O_3, holds for the 'ferrate glasses containing a large amount (-30 mol%) of Fe_2O_3. Less

玻璃的热处理导致从玻璃到玻璃陶瓷的结构变化，其中沉淀出具有“纳米尺寸”的若干晶体颗粒。这种结构变化，即，玻璃的晶化导致了玻璃的电导率、磁性、光学透明度等性能的急剧变化。本文采用穆斯堡尔效应、红外光谱、磁化率、X射线衍射、差热分析等方法，对微晶玻璃的晶化机理以及结构与物理性能的关系进行了研究。（1）半导性25K_2O·65V_2O_5·10Fe_2O_3玻璃在晶化温度（Tc）附近短时间（10-30 min）热处理，由于结构弛豫，电导率从10^<-8>S·cm ~ 2量级跃变<-1>到10^<-4>S·cm ~ 2量级<-1>。经长时间热处理后，由于预浸温度的升高， ...更多信息 2）对60 CaO·27Al_2O_3·13Fe_2O_3和60 CaO·10 BaO·17Al_2O_3·13Fe_2O_3两种铝酸盐红外透射玻璃进行热处理，由于反铁磁Ca_2Fe_2O_5纳米粒子的析出，导致样品的红外透过率和磁化率下降。3）激活能（Ea）结晶所需的键能等于结构单元的键能（例如，Ca-O和Al-O键），表明化学键的断裂触发结晶。在钒酸盐和钨酸盐玻璃中，含铁（Fe（III），等于Fe-O键能）的情况下，Ea值降低到2.6 eV。4）玻璃转变温度（Tg）与穆斯堡尔参数之一的四极分裂（DELTA）的大小成比例，如Nishida等人1所发现的。（“Tg-DELTA规则”，1990年）。在玻璃化转变温度附近热处理，由于SiO_4和FeO_4四面体畸变的减少，玻璃的玻璃化转变温度与Fe（III）的Δ值一致下降。对于含有大量（~ 30mol%）Fe_2O_3的高铁酸盐玻璃也成立。少

项目成果

T.Nishida, S.Kubuki, M.Shibata, Y.Maeda, and T.Tamaki: "Crystallization Mechanism of Aluminoferrate Glass Accompanying a Precipitation of Nanocrystals of Dicalcium Ferrite (Ca_2Fe_2O_5)and Maynite (12CaO・7Al_2O_3)" Journal of Materials Chemistry. 7(9). 18

T.Nishida、S.Kubuki、M.Shibata、Y.Maeda 和 T.Tamaki：“铝铁酸盐玻璃的结晶机制伴随着铁酸二钙 (Ca_2Fe_2O_5) 和 Maynite (12CaO·7Al_2O_3) 纳米晶体的沉淀” 材料化学杂志.7(9).18

T.Nishida: Mossbauer Spectroscopy of Sophisticated Oxides. Akademiai Kiado (Budapes), 340 (1997)

T.Nishida：复杂氧化物的穆斯堡尔谱。

S.Kubuki: "Mossbauer Study on the Crystallization of IR-Transmitting Aluminate Glasses" Journal of Radioanalytical and Nuclear Chemistry. (in press).

S.Kubuki：“红外传输铝酸盐玻璃结晶的穆斯堡尔研究”放射分析和核化学杂志。

T.Nishida, S.Kubuki, and Y.Maeda: "Application of the Tg-DELTA Rule to the Local Structural Study of Ferrate Glasses" Journal of Radioalytica and Nuclear Chemistry. (in oress).

T.Nishida、S.Kubuki 和 Y.Maeda：“Tg-DELTA 规则在高铁酸盐玻璃局部结构研究中的应用”《放射分析与核化学杂志》。

T.Nishida: "″Mossbauer Spectroscopy of Sophisticated Oxides″" Akademiai Kiado(Budapest), 340 (1997)

T.Nishida：“复杂氧化物的穆斯堡尔光谱”Akademiai Kiado（布达佩斯），340（1997）