We have used atomic force microscopy to study tobacco mosaic virus deposited on mica by the evaporation of films of dilute solutions of TMV. Solutions of TMV in distilled deionized water deposit TMV aggregates similar to those seen by electron microscopy on other substrates. However, solutions containing both TMV and bovine serum albumin (BSA) deposit unaggregated, randomly oriented TMV rods. High-resolution AFM images taken under 2-butanol reveal that numerous BSA molecules are attached to each TMV rod. We think that the attachment of BSA particles to TMV rods changes the intervirus interactions and results in dispersed TMV both in solution and on mica.

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The polycrystalline sample of a new tungsten bronze ferroelectric vanadate, Li 2 Pb 2 La 2 W 2 Ti 4 V 4 O 30 , was prepared at a relatively low temperature using a mixedoxide technique. The formation of the material under the reported conditions has been confirmed by an X-ray diffraction technique. A preliminary structural analysis exhibits orthorhombic crystal structure of the material at room temperature. Studies of dielectric properties (ε, tanδ) of the above compound as a function of temperature (273-600K) at frequencies 10, 100, 1000 KHz exhibits a ferroelectric phase transition of diffuse type. The electrical properties of the material have been studied using ac impedance spectroscopy technique. Detailed studies of impedance and related parameters exhibit that the electrical properties of the material are strongly dependent on temperature, and bear a good correlation with its microstructures. The temperature dependence of electrical relaxation phenomenon in the materials has been observed. The bulk resistance, evaluated from complex impedance spectra, is found to decrease with rise in temperature, exhibiting a typical negative temperature co-efficient of resistance (NTCR) -type behavior similar to that of semiconductors. A small contribution of grain boundary effect was also observed. The complex electric modulus analysis indicates the possibility of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation. The ac conductivity spectra exhibit a typical signature of an ionic conducting system, and are found to obey Jonscher's universal power law.

A polycrystalline ceramic, a new type of complex tungsten bronze type structure, having a general formula Li 2 Pb 2 Y 2 W 2 Ti 4 V 4 O 30 has been prepared relatively at low temperature using a mixed-oxide technique after optimizing the calcination conditions on the basis of thermal analysis. The material has been characterized by different experimental techniques. The formation of the material under the reported conditions has been confirmed by an X-ray diffraction technique. A preliminary structural analysis of the material showed the formation of single phase compound in an orthorhombic crystal structure at room temperature. Studies of dielectric properties (ε r , tanδ ) of the above compound as a function of temperature at different frequencies exhibit a ferroelectric phase transition of diffuse type. The electrical properties of the material have been studied using ac impedance spectroscopy technique. Detailed studies of impedance and related parameters exhibit that the electrical properties of the material are strongly dependent on temperature, and bear a good correlation with its microstructure. The temperature dependence of electrical relaxation phenomenon in the material has been observed. The bulk resistance, evaluated from complex impedance spectra, is found to decrease with rise in temperature, exhibiting a typical negative temperature co-efficient of resistance (NTCR)-type behavior similar to that of semiconductors. A small contribution of grain boundary effect was also observed. The complex electric modulus analysis indicates the possibility of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation. The ac conductivity spectra exhibit a typical signature of an ionic conducting system, and are found to obey Jonscher's universal power law.