Influence of eutectic addition on the electrical conductivity of Li2O:B2O3 system

Addition of three eutectics, Li₂SO₄:Li₂CO₃, 3Li₂O·Nb₂O₅:LiNbO₃ and AgI:Ag₂SO₄ has been tried in the Li₂O:B₂O₃ glass system. The electrical conductivity increases with the addition of eutectic. The amount of lithium fraction and the melting point of the eutectic govern the conductivity.     

Influence of Ag2SO4 addition on the electrical conductivity of the Li2O:B2O3 system

Glasses in the Li₂O:B₂O₃:Ag₂SO₄ system were prepared with varying silver sulphate contents. From the present results it can be said that the amorphous matrix accepts Ag₂SO₄ up to 5 mol% without any devitrification. The enhancement in conductivity with change in the structure of metaborate glass is due to Ag₂SO₄.     

TiO2掺杂的NiO-NiFe2O4电导率及合成动力学研究

采用固相合成法,在1173～1213K温度范围内合成了NiO-NiFe2O4和0.5%TiO2掺杂的NiO-NiFe2O4。用X射线衍射表征了合成产物。在合成过程中将试样置于两个铂片之间,通过连续测量加热过程中试样的电阻,获得了试样电导率随时间的变化规律,建立了稳态扩散控制的NiFe2O4合成动力学方程,并讨论了掺杂0.5%TiO2对NiFe2O4合成反应速率的影响,获得了0.5%TiO2掺杂的NiFe2O4合成反应的速率系数、活化能、Ni 2＋和Fe3＋离子的平均扩散系数。     

DC electrical conductivity of CoSiF6·6H2O and (NH4)2SO4

D.C. electrical conductivity of single crystals of (NH₄)₂SO₄ and CoSiF₆·6H₂O have shown conductivity jump near their respective structural transition temperature. Activation energy of (NH₄)₂SO₄ has been found to be consistent with the earlier data. However, CoSiF₆·6H₂O has given prolonged aging effect due to dipolar relaxation and formation of space charge polarisation.σ _true andP _max have been measured.P _max has shown a negative maximum at the transition point. Activation energy of ZnSiF₆·6H₂O has been found to be comparable with CoSiF₆·6H₂O.     

DC electrical conductivity of Na2O-ZnO-B2O3 glass system

The d.c. electrical conductivity of Na₂O-ZnO-B₂O₃ glass system has been measured as a function of temperature in the range of 350–600°K. The conductivity data show that the activation energy of Na⁺ ions is dependent on ZnO concentration. The results have been discussed in the light of the cluster model of glasses.     

(Y2O3,Yb2O3)复合掺杂ZrO2材料的中低温电导率

采用交流复阻抗体技术对（Y2O3，Yb2O3)复合掺杂ZrO2材料在573－873K这一温度范围的离子电导率随组成的变化关系进行了研究，发现在ZrO2-Y2O3系统加入Yb2O3会使得材料在中低温区域电导率降低。用经典的Arrhenius公式对实验数据进行的分析表明，导导率降低的原因在于Yb^3＋与结构中氧空位之间的缔合比Y^3 与氧空位之间的缔合更甚，阻碍了氧空位在中低温下的定向迁移。     

Glass formation in the system CaO-Al2O3-CaF2

The formation of glass in the system CaO-Al₂O₃-CaF₂ has been investigated in sealed platinum capsules having about one atmosphere pressure of AlF₃ vapour. Transparent colourless glass could be obtained in the low-fluoride moderate-alumina region of the system (Al₂O₃ 35 to 60%, CaF₂ 0 to 20%). With the concentration of CaF₂ exceeding 20% considerable amount of quench crystals of CaF₂ appeared in the glass. Moderate-alumina low-lime melts containing more than 35% CaF₂ occur in an immiscibility zone. At the low-fluoride periphery of the liquid immiscibility zone a small zone of metastable liquid immiscibility has been found. The results of electron microscopic and infra-red spectroscopic studies of a few selected glasses have been analysed in combination with the molar refractivity data to reflect upon the co-ordination characteristics of aluminium in these glasses.     

Enhancement in electrical conductivity of Li<Subscript>2</Subscript>O: B<Subscript>2</Subscript>O<Subscript>3</Subscript>: V<Subscript>2</Subscript>O<Subscript>5</Subscript> glasses

The study of electrical conductivity of 30Li₂O: (70 − x) B₂O₃: xV₂O₅ glass samples has been carried out. The results have been explained by dividing the temperature range into two regions. In region I, conductivity shows Arrhenius behaviour for all the samples. The conductivity increases with addition of V₂O₅. The results have been explained in the light of Anderson and Stuart Model. In region II, an anomalous enhancement in the conductivity is observed for all the samples up to certain temperature beyond which the conductivity decreases. The enhancement in the conductivity in the annealed glass sample has been attributed to nanocrystallization.     

An analysis of the electrical conductivity of the Ag2SO4-K2SO4 binary system

Electrical conductivity of the Ag₂SO₄-K₂SO₄ binary system shows three maxima at 20, 70 and 90 mole% of K₂SO₄ added to Ag₂SO₄. The first and the third maxima have been explained in the light of intragrain percolation due to lattice distortion, whereas, the second maximum by the surface percolation. The limit of solid solubility has been set at 20 mole% on the basis of evidences obtained from XRD, DTA and SEM techniques.     

Glass formation and immiscibility in the TeO2-B2O3-Fe2O3-MnO system

The glass formation in the quaternary TeO₂-B₂O₃-MnO-Fe₂O₃ system and in its ternary systems was investigated. A range of liquid immiscible phases, located near to the binary TeO₂-B₂O₃ and B₂O₃-MnO systems was established. Using transmission electron microscopy, a trend to metastable liquid-phase separation in the single-phase glasses, located near to the boundary of immiscibility was observed. With an increase in the Fe₂O₃ and MnO content still in the process of cooling of the melts, it was possible for a fine glassy crystalline structure to be formed in them. It was shown that by changing the upper limit of the melting temperature and the cooling rate, the glassy crystalline structure and the Fe₃O₄ content could be modified.     

An analysis of the electrical conductivity in BaSO4-added Ag2SO4 solid electrolyte system

The compositions (1 −x)Ag₂SO₄−(x)BaSO₄, wherex=0·01 to 0·6, were prepared by slow cooling of the melt. The extent of the solid solubility of Ba²⁺ in Ag₂SO₄ was determined by X-ray powder diffraction and scanning electron microscopy. The bulk conductivity of each sample was obtained using a detailed impedance analysis. The partial substitution of Ba²⁺ results in the enhancement of conductivity in compliance with the classical aliovalent doping theory. A simplistic model based on lattice distortion (expansion) due to partial substitution of Ag⁺ by the bigger Ba²⁺ has been considered to explain enhanced conductivity. Beyond solid-solubility limit (5·27 mole%) the BaSO₄-dispersed Ag₂SO₄ conductivity follows the usual trend seen in binary systems. An increase in conductivity in this case is discussed in the light of interfacial reactions and surface defect chemistry. The maximum conductivity in 20 mole% BaSO₄ dispersed Ag₂SO₄ is due to percolation threshold.     

EPR and Magnetic Susceptibility Investigation of Fe Ions in B2O3—SrF2 Glass Matrix

The structural and magnetic properties of an oxide-fluoride mixed vitreous matrix 2B2O3-SrF2, were explored by using Fe impurities as probes.Information about the structural units involving iron ions,their valence state,the strengths and type of interactions involving them was obtained using EPR spectroscopy and magnetic susceptibility measurements.     

Excited state characteristics of the Li2B4O7 and KLiB4O7 glasses activated by Cr3+ ions

The excited state characteristics by means of the excited state absorption (ESA), optical gain and bleaching spectra have been measured for prototype glasses with Li₂B₄O₇ (LBO) and KLiB₄O₇ (KLBO) compositions activated by Cr³⁺ ions. The work addressed to search for novel attractive media for broadband lasers and amplifiers, is a completion of detailed spectroscopic evaluation described in earlier papers. One of the examined materials (KLBO), in accordance with optimistic comments given in previous work, reveals a very broad gain spectrum in the near IR, which itself is interesting in view of very few reports on glasses showing optical gain for Cr³⁺ ions in the low-field local environment. The ESA/gain/bleaching spectra, registered with equipment of improved sensitivity, have been reproduced by calculations, and detailed single configuration coordinate diagram, based on experimental data, has been created for interpretation.     

Glass formation in the ZrF4-PbF2-LaF3-NaF system

Glass formation in the ZrF₄-PbF₂-LaF₃-NaF system is studied by differential thermal analysis at ZrF₄ contents of 65 and 70 mol %. The glass-forming region is outlined, and the composition dependences of glass stability parameters are presented.     

Thermal conductivity and electrical resistivity of cadmium arsenide (Cd3As2) in the temperature range 4.2–40 K

Results on electrical resistivity and thermal conductivity measured in the temperature range 4.2–40 K are presented for single-crystal and polycrystalline samples of Cd₃As₂. Hall effect has been studied at temperatures of 4.2, 77, and 300 K. The calculated value of the conduction electron concentration was in the range 1.87–1.95 10²⁴m^–3. Electrical resistivity of all investigated samples was independent of temperature up to about 10K and increased slowsly at higher temperatures. The thermal conductivity shows a maximum in the region in which the lattice component of thermal conductivity dominates. The strong anisotropy of the lattice component determines the anisotropy of the total thermal conductivity. The electronic component of thermal conductivity does not exhibit any anisotropy and shows a maximum at a temperature of about 300 K.Paper submitted to the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Effect of dopant concentration on electrical conductivity in the Sc2O3-ZrO2 system

Electrical conductivity measurements have been made as a function of dopant concentration (4 to 8 mol% Sc₂O₃) in the scandia-zirconia system, All the compositions studied had a tetragonal structure. The hombohedral phase was present only in samples prepared from mechanical mixtures of Sc₂O₃ and ZrO₂. In specimens prepared by coprecipitation, no phase lines were observed and the monoclinic zirconia (m-ZrO₂) phase was present for only Sc₂O₃ contents 5 mol %. The conductivity of Sc₂O₃-ZrO₂ decreased continuously with time up to 300 h anneal time between 700 and 1000° C. X-ray diffraction of coprecipated specimens of 7.8 mol % Sc₂O₃-ZrO₂ composition annealed at 1000° C (28 days), 750° C (42 days) or 460° C (189 days) did not reveal any changes to account for this. However, transmission electron microscopy showed that changes associated with the formation of very fine precipitates had occurred. The activation energy for conduction in the low-temperature region decreased monotonically with decrease in the scandia content. Jumps in the conductivity curves and hysterisis effects were observed in specimens containing m-ZrO₂.