Sintering and humidity-sensitive behaviour of the ZnCr2O4-K2CrO4 ceramic system

Bayhan, M
Hashemi, T
Brinkman, AW
Solid state reaction at elevated temperatures and the sintering behaviour of zinc chromite formed by zinc oxide and chromite oxide were investigated. Crystalline structure, surface and fractured morphologies and humidity-sensitivity characteristics of ZnCr2O4-K2CrO4-CuO were studied. The fired ceramic body, which proved to be mainly constructed from ZnCr2O4 spinel grains, was porous. The humidity characteristics of the sensor showed that the resistance decreased as a logarithmic function with an increase in humidity. The resistance values obtained were about 6 x 10(9) Omega and 3 x 10(4) Omega at 25 and 93% relative humidity (RH), respectively. Based on a.c. impedance measurements, an equivalent circuit associated with a network of resistors together with series capacitors has been suggested. It is assumed that such an equivalent circuit model of the sensor under the moist conditions represents the sensing mechanism as a diffusion process.


DAG, O; KUPERMAN, A; OZIN, GA (Wiley, 1994-02-01)
Uniform arrays of intrazeolite germanium nanoclusters have been produced by the topotactic chemical vapor deposition of digermane within the diamond network of alpha-cages of acid zeolite Y and the main channel of mordenite. The conditions within the zeolite hosts ensure that the Ge2H2 CVD-type anchored precursors self-assemble to produce the anchored (Ge8)n+ nanoclusters shown in the Figure.
Hot-pressed hydroxylapatite/monoclinic zirconia composites with improved mechanical properties
Evis, Zafer (Springer Science and Business Media LLC, 2007-04-01)
Composites of hydroxylapatite (HA) and monoclinic zirconia were hot-pressed at 1100 degrees C and 1200 degrees C under vacuum to study the phase transformations and the mechanical properties. X-ray diffraction results showed a higher phase transformation from monoclinic-ZrO2 to tetragonal-ZrO2 when the sintering temperature increased from 1100 degrees C to 1200 degrees C. HA decomposed faster when the amount of ZrO2 in the composites increased. Moreover, small amount of alpha-TCP and CaZrO3 was observed in ...
Microstructural investigation of Cu2+ doped nanohydroxyapatites
Evis, Zafer (Informa UK Limited, 2010-05-01)
Pure and Cu2+ doped nanohydroxyapatites were synthesised by a precipitation method to investigate the effect of Cu2+ ions on the structure of hydroxyapatite (HA) and its thermal stability after the air sintering at 1100 degrees C. A small amount of CaO was observed in the Cu2+ doped HAs after the X-ray diffraction results. The addition of Cu2+ changed the hexagonal lattice parameters of the HA and resulted in smaller grain size after sintering at 1100 degrees C. The addition of Cu2+ ions into HA resulted in...
Crystal data and indirect optical transitions in Tl2InGaSe4 crystals
QASRAWI, ATEF FAYEZ HASAN; Hasanlı, Nızamı (Elsevier BV, 2008-06-03)
The room temperature crystal data and the optical properties of the Bridgman method grown Tl2InGaSe4 crystals are reported and discussed. The X-ray diffraction technique has revealed that Tl2InGaSe4 is a single phase crystal of monoclinic structure. The unit cell lattice parameters, which were recalculated from the X-ray data, are found to be a = 0.77244 nm, b = 0.64945 nm, c = 0.92205 nm and beta = 95.03 degrees. The temperature dependence of the optical band gap of Tl2InGaSe4 single crystal in the tempera...
Crystallization kinetics of fluorophosphate glasses .1. Effect of composition and hearing rate
Ozturk, A (Springer Science and Business Media LLC, 1997-05-15)
Crystallization behaviour of glasses from the system AlF3-MF2-Ba(PO3)(2) (M = Ca, Mg, Sr, Ba) have been studied using differential thermal analysis as a function of Ba(PO3)(3). The kinetic parameters for crystallization, namely, the activation energy, E frequency factor, v, and Avrami exponent, n, were determined. E,v and n decreased with increasing Ba(PO3)(2). Crystallization commenced at higher temperatures and the crystal growth mechanism changed from bulk to surface with increasing Ba(PO3)(2). X-ray dif...
Citation Formats
M. Bayhan, T. Hashemi, and A. Brinkman, “Sintering and humidity-sensitive behaviour of the ZnCr2O4-K2CrO4 ceramic system,” JOURNAL OF MATERIALS SCIENCE, pp. 6619–6623, 1997, Accessed: 00, 2020. [Online]. Available: