| 1. |
- Lu, W., et al.
(författare)
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Nondestructive determination of sheet carrier density in pseudomorphic AlGaAs/InGaAs/GaAs high electron mobility transistor structures by room-temperature photoluminescence spectra
- 1998
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Ingår i: Journal of Physics D-Applied Physics. ; 31:2, s. 159-164
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a nondestructive method to determine the sheet carrier density of pseudomorphic high electron mobility transistor structures by fitting the room-temperature photoluminescence (PL) spectra. The sheet carrier densities determined were in sufficiently good agreement with values determined by Hall measurements for different samples with different mole fractions, delta-doping densities and well widths. For single-doped AlGaAs/InGaAs quantum wells, the dominant emission is the transitions from the first electron subband to the first heavy hole subband, from the first electron subband to the second heavy hole subband, and from the second electron subband to the first heavy hole subband.
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| 2. |
- Singh, Maneesh, et al.
(författare)
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Preparation of iron rich cements using red mud
- 1997
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Ingår i: Cement and Concrete Research. - 0008-8846 .- 1873-3948. ; 27:7, s. 1037-1046
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Tidskriftsartikel (refereegranskat)abstract
- Possibility of producing calcium sulfoaluminoferrite (SAF) (C4(A,F)3S over-bar )-calcium aluminoferrite (C4AF) based cements using lime + red mud + bauxite + gypsum has been investigated. The effects of composition, firing time and firing temperature on the properties of cements produced has been studied. The characteristics of the cements produced have been found to be strongly dependent on the raw mix composition and firing temperature but not so much on firing time. Some of these cements possess strengths comparable to and at times even more than ordinary Portland cement (OPC). Since the red mud used contains significant amount of titania, effect of titania on pure sulfoaluminate phase has also been studied.
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| 3. |
- Singh, Maneesh, et al.
(författare)
-
Preparation of special cements from red mud
- 1996
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Ingår i: Waste Management. - 0956-053X .- 1879-2456. ; 16:8, s. 665-670
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Tidskriftsartikel (refereegranskat)abstract
- Red mud from HINDALCO (Hindustan Aluminium Corporation) Industries Limited, Renukoot, India, contains significant quantities of alumina, iron oxide and silica. Presence of the said constituents makes it a suitable ingredient for the preparation of special cements. Preparation of three varieties of cements was investigated, namely: (a) aluminoferrite (C4AF)- belite (β-C2S) using lime + red mud + fly ash; (b) aluminoferrite-ferrite (C2F)-aluminates (C3A and C12A7) utilising lime + red mud + bauxite; and (c) sulfoaluminate (C4A3S̄)-aluminoferrite-ferrite using lime + red mud + bauxite + gypsum. The effects of composition (proportions of lime, red mud, fly ash, bauxite and gypsum), firing temperature and duration on the properties of cements produced were studied in detail. Cements made from lime + red mud + bauxite or lime + red mud + bauxite + gypsum exhibit strengths comparable or superior to ordinary Portland cement (OPC). On the other hand, those prepared using lime + red mud + fly ash did not have sufficient strength. Moreover, it was not possible to replace bauxite by fly ash (as a source of alumina) in any significant quantity.
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