X-ray, SEM, far IR characterization and bulk magnetic properties of Zn²⁺ substituted copper ferrite synthesized by co- precipitation technique

207-214The alternating current (ac) low field susceptibility vs temperature and magnetization measurements are reported for the spinel solid solution series ZnxCu1-xFe2O4 (x = 0.0, 0.2, 0.4, 0.5, 0.6, 0.8) synthesized by a wet-chemical method before and after high temperature annealing. The low values of lattice constant, magneton number and Neel temperature for wet-samples (W) as compared to annealed wet (A W) <span style="font-size:14.0pt;line-height:115%;font-family: " times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;color:black;mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">samples are explained on the basis of fine particle nature of wet samples. The high temperature annealing changes the wet-prepared ferrites into ordered magnetic structure of ceramic ferrites. The Neel temperature calculated theoretically are in good agreement to those deduced experimentally. Scanning electron micrographs are used to see the grain growth and homogeneity of the samples while infra red spectra are used to determine water and sulphate content and to confirm ordered spinel ferrite structure.</span

Synthesis, characterization and microbial assay of new pyridoquinolone-3-carboxamides

880-890The ethyl pyrido[2,3-h]quinolone carboxamides 7-31 have been synthesized and their ability to inhibit Gram positive strains B. subtilis and S. aureus and Gram negative strains E. coli and P. aeruginosa have been tested. Only carboxamides with piperazine derivatives attached at C-3 position show good antibacterial potency compared to standard ciprofloxacin and gatifloxacin. Piperazine derivatives attached at C-3 position of N-ethyl pyrido quinolone increase the activity of their parent compound acid 6, whereas aryl urea attached at this position decrease the antibacterial activity

<span style="font-size:12.0pt;line-height: 115%;font-family:"Times New Roman","serif";mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-IN;mso-fareast-language:EN-IN;mso-bidi-language:HI" lang="EN-IN">Effect of Fe³⁺ substitution on structural and macro-magnetic properties of yttrium iron garnet</span>

502-506The structural and bulk magnetic properties of Fe3+ substituted yttrium iron garnet with general formulaY3-xFe5+xO12 (x = 0.0, 0.05, 0.15,0.30 and 0.50) have been investigated by means of X-ray diffraction, EDAX, high field magnetization and low field a.c. susceptibility measurements. It is found that substituted Fe3+ ions occupy c-sites and increase in lattice constant for x&gt; 0.30 is due to presence of Fe2+ ions, determined through EDAX, on a-sites. Variation of magneton number with x can be explained satisfactorily assuming the collinear spin ordering model and Neel temperature values deduced experimentally from a.c. suscepti bility measurements are in good agreement to those calculated theoretically