Phase formation during liquid phase sintering of ZnO ceramics

Arefin, Mohammad Lutful; Raether, F.; Dolejš, David; Klimera, Andreas

doi:10.1016/j.ceramint.2009.05.030

Cited by 35 publications

(35 citation statements)

References 15 publications

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“…2,[68][69][70][71][72][73] This is reported as due to the creation of liquid bismuth along the ZnO grain boundaries, which enhances the grain boundary movement and thus facilitates the grain growth. [68][69][70][71][72][73] These observations further demonstrate that controlling the grain size during sintering at high temperature remains a real challenge in conventional ceramic processing. [69][70][71][72][73] It is possible that other sintering procedures such as step sintering or microwaveassisted sintering might be applied to get a fully sintered varistor disc at a lower temperature.…”

Section: -6mentioning

confidence: 99%

“…Aren et al 68 performed thermodynamic calculations to predict the phase formation, composition and stability of additive oxides during the sintering process of ZnO varistors. They modelled the phase formation during sintering in the Zn-Bi-O and Zn-Bi-Sb-O mixtures (Fig.…”

Section: 368-73mentioning

confidence: 99%

“…2,9,31-44, [46][47][48][49][50][51][52][53][54][55][56][57]68 This formation of bismuth-rich phases has been analysed using XRD, FESEM and EDX analysis ( Fig. 3 and 4).…”

Section: -6mentioning

confidence: 99%

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Advances in the synthesis of ZnO nanomaterials for varistor devices

et al. 2013

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adZnO based varistors are widely used for overvoltage protection in many electrical and electronic circuits, at voltages ranging from a few to over a million volts. By careful control of the microstructure, through nanostructuring by chemical routes, it should be possible to produce varistors with high breakdown voltage (V c ), as this is proportional to the number of active grain boundaries in the sintered body. This property is particularly important for the production of the small-sized varistors needed for modern electronic instruments such as tablet computers and mobile phones. The current review will outline the recent advances in the chemical processing (e.g. sol-gel, combustion synthesis plasma pyrolysis, micro-emulsion synthesis and precipitation routes) of varistors from ZnO nanomaterials and the properties of these materials. Uncontrolled grain growth at higher temperature is highlighted as a major challenge for obtaining desirable electrical properties for nano-varistors. Various novel sintering techniques such as step-sintering, spark plasma and microwave sintering methods are expected to deliver a varistor with controlled grain growth and optimum electrical characteristics.

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Section: -6mentioning

confidence: 99%

Section: 368-73mentioning

confidence: 99%

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Advances in the synthesis of ZnO nanomaterials for varistor devices

et al. 2013

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“…Antimony oxide is used in the varistor to reduce the average size of the ZnO grain [17][18][19]. The microstructure of the MOV contains three phases, the most dominant phase being that of the zinc oxide grains.…”

Section: And Toni Karlssonmentioning

confidence: 99%

Recovery of Antimony: A Laboratory Study on the Thermal Decomposition and Carbothermal Reduction of Sb(III), Bi(III), Zn(II) Oxides, and Antimony Compounds from Metal Oxide Varistors

Karlsson

Forsgren

Steenari

2018

J. Sustain. Metall.

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As antimony is typically present in industrial and commercial products only in small amounts, the concentration of antimony in waste types is low and a limited amount of antimony is currently recycled. One product relatively rich in antimony is the metal oxide varistor (MOV) used for overvoltage protection in electric circuits. To increase the antimony concentration, the MOV was pulverized (\ 65 lm) and leached, resulting in an insoluble MOV residue containing 186 ± 2 mg/g of antimony. This work investigates the thermal decomposition and carbothermal reduction of pure metal oxides (Sb 2 O 3 , Bi 2 O 3 , and ZnO) and MOV residue. Thermogravimetric (TG) analysis was used in order to propose a temperature range in which it is possible to separate antimony oxide from the MOV residue. TG results indicate that during thermal decomposition of pure metal oxides, sublimated antimony oxide can be recovered at 650°C, leaving Bi 2 O 3 and ZnO unreacted. The addition of carbon caused mainly volatilization, with some reduction, of Sb 2 O 3 and reduction of Bi 2 O 3 to occur at nearly the same temperature, approximately 600°C. However, volatilization of Bi was not troublesome below 800°C due to slow kinetics. Thermal decomposition of antimony from the MOV residue was not possible in the temperature range studied (\ 1000°C), while carbothermal reduction to the MOV residue revealed antimony volatilization occurred near 800°C.

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“…Nevertheless, the reactions and hence the phase composition of the varistor ceramics are basically determined by the ZnO-Bi 2 O 3 -Sb 2 O 3 system. ; it dissolves other dopants and ensures their uniform distribution, promotes sintering and enhances grain growth, which all benefit the I-U characteristics of the varistor ceramics [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%