This paper reports, for the first time, observation of sassolite (crystalline B(OH)3) formation in alkali borosilicate glass (BSG) powder due to hydration during aging. Correlation between hydration ...behavior, sassolite formation, and phase separation has been established and hydration‐resistant low‐alkali BSG powders were successfully prepared. The glass composition exhibited very low moisture absorption of <3 wt% in powder form, for an aging duration of 6000 h. This has been achieved by carefully tailoring the glass transition temperature (Tg) and critical immiscibility temperature (Tc). We also report a new, simple, and effective sample preparation method for detecting phase separation in BSG, using transmission electron microscopy.
A 2–2 bilayer composite 0.50Pb(Ni1/3Nb2/3)O3–0.35PbTiO3–0.15PbZrO3(PNNZT)/CoFe2O4 (CFO) thin film has been fabricated using a pulsed laser deposition technique. Due to the coexistence of ...ferromagnetic (FM) order in the CFO layer and ferroelectric (FE) order in the PNNZT layer, the product property, i.e., the magnetoelectric (ME) coupling has been realized with a ME voltage coefficient (αE) of ~500mV/cm.Oe and a magnetodielectric response (MD(%) of 0.27 at room temperature. The present new composite thin film with its enhanced ME and MD properties could be a useful material for developing ME-based devices.
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Stoichiometric nano sized copper ferrite particles were synthesized by sol gel combustion technique. They were then calcined at various temperatures ranging from 300–800°C and were either furnace ...cooled or quenched in liquid nitrogen. A high magnetisation value of 48.2emu/g signifying the cubic phase of copper ferrite, was obtained for sample quenched to liquid nitrogen temperature from 800°C. The ethanol sensing response of the samples was studied and a maximum of 86% response was obtained for 500ppm ethanol in the case of a furnace cooled sample calcined at 800°C. The chemical sensing is seen to be correlated with the c/a ratio and is best in the case of tetragonal copper ferrite.
•One of the first study on ethanol sensing of cubic copper ferrite.•In-situ High temperature XRD done shows phase transition from cubic to tetragonal.•A non-monotonic increase in magnetization was seen with calcination temperature.•A response of 86% was obtained towards 500 ppm ethanol.•Tried to correlate sensing response and ion content in spinel structure.
The synthesis and characterization of magnesium ferrite MgFe2O4 prepared by co-precipitation and sol gel combustion is reported. Structural characterization showed that all the samples have single ...spinel phase. The co-precipitated sample exhibits smaller grains and twice higher BET surface than the sol gel combustion samples. The powder was shaped to dedicated chemo-resistive home-made sensors devices. The electrical properties and sensing properties towards carbon dioxide of both MgFe2O4 powders were studied. The type of charge carriers were analysed on the basis of the change in resistance in the presence of air and argon. The sensing response towards CO2 was found to be dependent on the morphology of the powder sample and the CO2 concentration. A high response of 36% towards 5000 ppm of CO2 was reached which is good for this gas. The key role of the Mg ions modulating the electrical properties is discussed.
•Two synthesis methods (co-precipitation and solgel combustion) yielded same structure with different microstructure.•A response of up to 36% could be obtained for the first time for CO2 sensing with magnesium ferrite powders.•Mg-ferrite generates different reaction mechanisms with gas than other spinel ferrite.•Air/Ar measurements confirmed the charge carriers where n-type in both samples.
Study of pulsed laser deposited magnetite thin film Bohra, Murtaza; Venkataramani, N.; Prasad, Shiva ...
Journal of magnetism and magnetic materials,
03/2007, Letnik:
310, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
Magnetite thin film with a predominant (1
1
0) texture has been deposited by pulsed laser ablation of α-Fe
2O
3 target onto fused quartz substrate. Spontaneous magnetization of 5400
G and room ...temperature electrical resistivity of 4.2×10
−3
Ω
cm were measured for an annealed magnetite thin film. Zero-field-cooled magnetization data clearly show the Verwey transition near 120
K through an abrupt change, and is consistent with the resistivity measurement.
Engineering magnetic materials into a thin film form while preserving its excellent magnetocaloric response is essential in the development of miniature magnetic coolers. We demonstrate how this can ...be achieved in the case of EuTiO3 - an emerging multiferroic material. Unlike conventional cases where reduced dimensionality considerably decreased the magnetic entropy change (ΔSM) and hence the refrigerant capacity (RC), we show the large low-field enhancements of ΔSM and RC in a ~100 nm thick nanocrystalline EuTiO3 film (ΔSM ~ 24 J kg-1K-1 and RC = 152 J kg-1 for μ0ΔH = 2T) relative to its single crystal counterpart (ΔSM ~ 17 J kg-1K-1 and RC ~ 107 J kg-1 for μ0ΔH = 2T). The nanocrystalline EuTiO3 film is an excellent candidate for cryogenic magnetic refrigeration. From our study, a new approach for improving both MCE and RC in magnetic nanomaterials is proposed, which will stimulate further research on magnetocaloric thin films and related cooling devices.
Room temperature multiferroism with enhanced ferro and piezoelectric properties of a new lead-free MnO2 added 0.90(Li0.12Na0.88NbO3)-0.10BaTiO3 ceramic is reported. The addition of MnO2 as an ...additive resulted in a two fold increase in remnant polarization (Pr) (from ~7.30 to 17.20μC/cm2), ~50% increase in large-signal piezoelectric coefficient (d33∗) (from ~117 to176pm/V) and symmetric butterfly loop are observed. Phase analysis revealed that MnO2 entered the host lattice as Mn2+ and Mn4+-ions and induced room temperature ferromagnetic-like character. Interestingly, an intrinsic coupling between the two ferroic orders is evidenced by the observation of a magneto-electric voltage coefficient (αE) of ~0.94mV/cm.Oe.
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•Structural and magnetic properties of PLD Co1−xZnxFe2O4 films are investigated.•MS values higher than equivalent bulk are observed for the films with x=0.1 & 0.7.•The high MS in thin films are ...correlated to the deviation in cation occupancy.
The magnetic properties of pulsed laser deposited Co-Zn ferrite Co1−xZnxFe2O4 (0.1≤x≤0.7) nanocrystalline thin films have been investigated. The films were deposited on amorphous quartz substrate. The observed magnetic properties of the films depend on the deposition temperature (TS), the annealing temperature (TA) and the Zn content (x). A magnetization value higher than bulk was observed in a room temperature deposited Co rich (x=0.1) Co-Zn ferrite thin films, when the films were ex-situ annealed at TA=750°C. On the other hand, in Zn rich (x=0.7) Co-Zn ferrite, a magnetization value higher than bulk (x=0.7) was obtained in a film deposited at TS=750°C. The unusual magnetization values are explained on the basis of grain growth and the cation distribution in thin films.
Electronic transport in hydrogenated microcrystalline silicon (μc-Si:H) films largely depends on size and shape of small crystallites columnar grains, the fraction of amorphous silicon (a-Si:H) ...matrix, and the highly defective grain boundaries (GBs). Based on these we describe two simple 1-D models of μc-Si:H depending upon the conduction path. Two applications of these models are presented using AMPS-1D. First, we study the electronic transport in intrinsic μc-Si:H for thin-film transistor (TFT) application. Second, we analyze the performance of thin film p-i-n μc-Si:H solar cells with varying column heights in the intrinsic μc-Si:H layer. Such a study should lead to the identification of optimum process conditions of the preparation of these films by the Cat-CVD process.
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