Inversion boundary induced grain growth in TiO2 or Sb2O3 doped ZnO-based varistor ceramics

Bernik, Slavko; Daneu, Nina; Rečnik, Aleksander

doi:10.1016/j.jeurceramsoc.2004.03.004

Cited by 86 publications

(62 citation statements)

References 18 publications

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“…Careful control of the microstructure is required to produce a high performance varistor. An ideal varistor should consist only of homogenously distributed ZnO grains with highly resistive grain boundaries and without secondary phases [11]. Due to the many variables involved in the manufacturing process obtaining this ideal is difficult.…”

Section: Introductionmentioning

confidence: 99%

The effect of vibratory milling on the powder properties of zinc oxide varistors

Kelleher¹,

Hashmi

2008

Journal of Materials Processing Technology

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The formation of powders from multi-elemental oxides for the subsequent formation of a green and sintered compact body is a major processing operation in the manufacture of ZnO varistors. The physical and chemical properties of the metal oxides are crucial not only for the formation of a varistor component with optimum microstructure and thus electrical characteristics but also for avoiding the introduction of flaws and reduced yield during subsequent manufacturing stages. The effect of vibratory milling using cylindrical zirconia media on the physical and chemical properties of the mixed multi-elemental oxide additives of a commercial ZnO varistor formulation was studied. These properties include particle size distribution, specific surface area, pore size distribution and zirconium concentration. They were evaluated by laser diffraction, Braunauer, Emmett and Teller (B.E.T.), mercury porosimetry and inductively coupled plasma (I.C.P.) analysis respectively. It was found that all of the physical and chemical properties of the metal oxide additives changed with increased duration of vibratory milling. The change in these properties was compared, a model of the powder morphology constructed and their significance analysed.

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Section: Introductionmentioning

confidence: 99%

The effect of vibratory milling on the powder properties of zinc oxide varistors

Kelleher¹,

Hashmi

2008

Journal of Materials Processing Technology

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“…(3) O coeficiente de não-linearidade (α), que corresponde ao recíproco da inclinação da curva U x I na região não linear, o valor da corrente de fuga e o valor de tensão de ruptura são importantes propriedades dos materiais varistores que são atribuídas às características microestruturais do material (densificação, tipos e distribuição das fases formadas, tamanho e distribuição de tamanho de grão. (4,5,6) Essas características microestruturais são, por sua vez, fortemente dependentes das rotas de processamento e da composição do material. Dessa forma, na literatura são encontrados diversos trabalhos sobre a adição de dopantes e uso de diferentes rotas de processamento que culminam na melhoria das propriedades do material varistor.…”

Section: Introductionunclassified

CARACTERIZAÇÃO MICROESTRUTURAL E COMPOSICIONAL DE MATERIAL VARISTOR COMERCIAL À BASE DE ÓXIDO DE ZINCO (ZnO) DOPADO

Ramos¹,

Dias²,

Furtado³

2017

Anais Do Congresso Anual Da ABM

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ResumoCaracterísticas microestruturais são determinantes para as propriedades não ôhmicas de materiais varistores, uma vez que elas se relacionam com o coeficiente de não linearidade das curvas U x I, com a capacidade de absorção de energia, e com o seu grau de confiabilidade. O presente trabalho tem por objetivo a análise composicional e microestrutural de um material varistor comercial a base de ZnO dopado com diversos óxidos, além de comparar a eficiência dos ataques químico e térmico para a visualização das imagens em MEV. Os resultados obtidos condizem com a literatura onde foi observada a predominância de grãos majoritariamente compostos por ZnO com a presença de segregações constituídas de diversos elementos e concentradas nos contornos de grão. Quanto aos ataques, foi notável uma melhor qualidade das imagens quando se adotou o ataque térmico do ponto de vista da visualização dos contornos de grão. O ataque químico, por sua vez, demonstrou ser mais eficiente na elucidação das fases segregadas e na revelação da porosidade do material varistor. Palavras-chave: Varistor; ZnO; Microestrutura; Ceramografia. MICROSTRUCTURAL AND COMPOSITIONAL CHARACTERIZATION OF A COMMERCIAL VARISTOR MATERIAL BASED ON DOPED ZINC OXIDE. AbstractMicrostructural characteristics are determinative for the non-ohmic properties of varistor materials since they relate with the nonlinear coefficient of the curves U x I, with the energy absorption capacity and with the degree of reliability. This work aims the compositional and microstructural analysis of a ZnO-based commercial varistor material doped with various oxides and to compare the efficiency of the chemical and thermal attacks for viewing images in SEM. The results are consistent with the literature in which the majority of grains mainly composed of ZnO in the presence of segregations composed by several elements and concentrated at grain boundaries was observed. As for the attacks, was remarkable better image quality when the thermal etching was adopted, from the standpoint of view of grain boundaries resolution.The chemical attack, in turn, shown to be more effective in elucidating the segregated phases and in revealing the porosity of varistor material.

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“…Titania and TiO 2 based semiconductors are of a considerable interest as catalysts, sensors, implants, medical media, corrosion protectors and electronic components widely studied and used in a variety of physicochemical, biological and industrial processes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Introducing dopants of multifarious characters (metals, nonmetals) [16][17][18][19][20][21][22] involves the band gap narrowing of titania materials which gives rise to energy saving for diverse technological purposes.…”

Section: Introductionmentioning

confidence: 99%

“…The low-dimensional particles are defined by several authors as Q-particles [27][28][29][30][31]. The band gap undergoes broadening in terms of the quantum size effect, what is conventionally described by Brus's equation [32] modified by Kayanuma [33] and other authors [34][35][36][37] (1) where r is the particle radius, * e m is the effective electron mass, (Fig. 1), let us show the energy level distribution cited as an example from [27].…”

Section: Introductionmentioning

confidence: 99%

Band-Gap Change and Photocatalytic Activity of Silica/Titania Composites Associated with Incorporation of CuO and NiO

Nazarkovsky¹,

Гунько²,

Wójcik³

et al. 2015

Him. Fiz. Tehnol. Poverhni

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Inversion boundary induced grain growth in TiO2 or Sb2O3 doped ZnO-based varistor ceramics

Cited by 86 publications

References 18 publications

The effect of vibratory milling on the powder properties of zinc oxide varistors

The effect of vibratory milling on the powder properties of zinc oxide varistors

CARACTERIZAÇÃO MICROESTRUTURAL E COMPOSICIONAL DE MATERIAL VARISTOR COMERCIAL À BASE DE ÓXIDO DE ZINCO (ZnO) DOPADO

Band-Gap Change and Photocatalytic Activity of Silica/Titania Composites Associated with Incorporation of CuO and NiO

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