Synthesis and characterization of novel binary organic monotectic and eutectic alloys

• Published in: Thermochimica acta Vol. 535; pp. 66 - 70
• Main Authors: Sharma, K.P., Rai, R.N.
• Format: Journal Article
• Language: English; Dutch
• Published: Oxford Elsevier B.V 10.05.2012; Elsevier
• Subjects: Chemical thermodynamics; Chemistry; Entropy; Eutectic temperature; Exact sciences and technology; General and physical chemistry; General. Theory; Growth kinetics; Interfacial energy; Lamellar structure; Mathematical analysis; Microstructure; Moles; Monotectic alloy; Phase equilibria; Roughness; Thermochemistry; Thermodynamics; Monotectic alloy; Phase equilibria; Thermochemistry; Microstructure; Growth kinetics
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/j.tca.2012.02.020

► The two novel phase diagrams of binary organic systems were studied. ► The various thermodynamic functions have been calculated. ► The optical microphotograph of monotectic shows lamellar structure. ► Growth kinetics of binary materials at different under cooling were studied. ► The relations between interfacial energies satisfy the Cahn's wetting condition. The phase diagram of biphenyl – 3-hydroxybenzaldehyde (BP–HB) shows the formation of a eutectic with HB-0.935mole% BP and 4-bromochlorobenzene –m-aminophenol (BCB–AP) show the formation of a monotectic (AP-0.150mole% BCB) and a eutectic (AP-0.996mole% BCB). The BCB–AP shows large miscibility gap where the consolute temperature is 12.5°C above the monotectic horizontal. Growth kinetics of pure components, the eutectics and the monotectic were studied by measuring the rate of movement of the solid–liquid interface which suggests the applicability of Hillig–Turnbull's equation. The thermodynamic functions such as heat of mixing, entropy of fusion, roughness parameter, interfacial energy and excess thermodynamic functions were calculated from the enthalpy of fusion values, determined by the DSC method. The relation between interfacial energies of monotectic system satisfies the Cahn's wetting condition. The optical microphotograph of monotectic shows lamellar structure whereas eutectics show broken lamellar and lamellar pearlite structures.