Thermodynamics of Cr2O3, FeCr2O4, ZnCr2O4, and CoCr2O4

Abstract

ABSTRACT

Synthesis and Characterization of ZnCr2O4 Nanospinel Prepared via Homogeneous Precipitation Using Urea Hydrolysis

“…Recently, spinel compounds with general formula of MCr 2 O 4 (M=Zn, Cu, Co, Ni, and Fe) have attracted considerable attention due to their physicochemical properties . In particular, zinc chromite (ZnCr 2 O 4 ) spinel is an extremely important functional material as humidity sensor, photocatalyst, catalytic material for a variety of reactions such as oxidation hydrogenation and steam reforming, and magnetic material …”

Thermodynamic aspects of transition metals doped ZnO

“…The lowtemperature heat capacity of ZnCr 2 O 4 has been measured [4] providing the value of entropy S m (298) = 128.6 J.mol -1 .K -1 . High-temperature heat capacity data are given in [5] where the consistent set of thermodynamic data for ZnCr 2 O 4 is also presented.…”

Síntesis y caracterización de la Espinela FeCr2O4

“…Compounds with spinel structures are known for having cations in their tetrahedral and octahedral structures, a fact that gives them versatility for technological applications given their physical and chemical properties (Ziemniak, Anovitz, Castelli y Porter, 2007, 1474-1492. Ferrites and chromites are especially interesting due to their diverse physical properties and their consequent versatility for technological applications (Gopal y Spaldin, 2006, 094418-9;Singh y Rhee, 2010, 1233-1237.…”

“…Os compostos com estrutura espinela se caracterizam por possuir em suas posições tetraedros e octaedros, o qual lhes permite ser versáteis em aplicações tecnológicas devido a suas propriedades físicas e químicas (Ziemniak, Anovitz, Castelli y Porter, 2007, 1474-1492. As ferrites e cromitas têm particular interesse, devido a suas diversas propriedades físicas, o qual lhes permite apresentar versatilidade ante aplicações de caráter tecnológico (Gopal y Spaldin, 2006, 094418-9;Singh y Rhee, 2010, 1233-1237.…”

“…Las ferritas y cromitas se han caracterizado por sus propiedades catalíticas, eléctricas, ópticas y magnéticas (Eppler, 1981;Eppler, 1982, 847-850;Richerson, 1992, 21-29;Ziemniak, Anovitz, Castelli y Porter, 2007, 1474-1492; es por ello que se utilizan ampliamente en dispositivos de aplicación en microondas, ordenadores, chips de memoria, medios de comunicación en medio magnético, materiales pigmentantes, entre otros (Morrison y Freund, 1967,1543Tseng;Kao;Shih;Huang;Wang &Chu, 2010, 212103-3;Wan, Li, Chen, Wang, He, Li y Lin, 2004,3654-3;Wang, Thomas y Brien, 2006, 21412-21415;Zheng, Yang;Zhang;Jiang;Mao;et al 2009, 221106-3). La aplicabilidad deseada en estos compuestos puede lograrse por la sustitución de diferentes cationes total o parcialmente en sitios tetraédricos u octaédricos.…”