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ABSTRACT. Density, ultrasonic speed measurements have been made for 2-hydroxy-5-methyl-3-nitroacetophenone (HMNAP) (0.06-0.21 mol . kg -1 ) in N,N-dimethylformamide (DMF) at four equidistant temperatures: 298.15, 303.15, 308.15 and 313.15 K. These measurements have been used to evaluate some important thermodynamic and acoustic parameters, such as apparent molar volume, limiting apparent molar volume, adiabatic compressibility, apparent molar adiabatic compressibility, limiting apparent molar adiabatic compressibility. The apparent molar volume (Vφ) and apparent molar adiabatic compressibility (Ks,φ), were computed using density data. These parameters, were used to discuss interactions between the ketonic (>CO) group and DMF molecule. The results are interpreted to gain insight in to the changes in molecular association equilibria and structural effects in these systems.

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The substituted Y type hexaferrites Sr 2 Zn 2 Al Fe 12− O 22 (where = 2, 4, 6, 10) are prepared by standard ceramic technique. The infrared absorption spectra of the prepared compounds are studied in the range 400 cm −1 to 4600 cm −1. These spectra are used to locate the vibrational ranges due to substituted cations with the nearest oxygen layers and also to understand the band positions attributed to the lattice sites. The absorption regions found around 460 cm −1 and 600 cm −1 are the common features of all spinel ferrites. Both X-ray and IR spectroscopic studies in these ferrites do not detect the presence of Fe 2+. Also with increase in aluminium substitution, the higher frequency bands start disappearing. This may be due to reduced vibrations of trivalent cations Fe-O bonds at both octahedral and tetrahedral sites which in turn affect Fe 3+-O 2−-Fe 3+ superexchange interactions present in the structure.