Ziarat Nemati - Academia.edu (original) (raw)

Papers by Ziarat Nemati

Research paper thumbnail of Photocatalytic activity of TiO2-capped ZnO nanoparticles

Journal of Materials Science: Materials in Electronics, 2011

Abstract Using a combined hydrothermal and sol–gel route, TiO 2-capped ZnO nanoparticles with an ... more Abstract Using a combined hydrothermal and sol–gel route, TiO 2-capped ZnO nanoparticles with an average size of 60 nm were prepared. The titania shell was amorphous with a thickness of~ 10 nm. Formation of Zn 2 TiO 4 phase at higher calcination temperature was noticed. Effects of Ti/Zn molar ratio and coating time on the thickness of TiO 2 shell and the photoactivity of the particles for decolorization of Methylene Blue (MB) under UV lamp irradiation (3 mW/cm 2) were investigated. The nanoparticles were characterized ...

Research paper thumbnail of Preparation and characterization of yttrium iron garnet (YIG) nanocrystalline powders by auto-combustion of nitrate-citrate gel

Journal of Alloys and Compounds, 2007

Research paper thumbnail of Study of microstructure and dielectric properties of PMN–PZT ceramics via a mixed powder method including sol–gel precursor

Journal of Alloys and Compounds, 2009

Research paper thumbnail of Template-directed hydrothermal synthesis of dandelion-like hydroxyapatite in the presence of cetyltrimethylammonium bromide and polyethylene glycol

Ceramics International, 2009

Research paper thumbnail of Effect of Surfactant in Formation of Hydroxyapatite Nano-Rods under Hydrothermal Conditions

Iranian Journal of …, 2008

Research paper thumbnail of Crystallization and electrical properties of V2O5 thin films prepared by RF sputtering

Applied Surface Science, 2007

Research paper thumbnail of Behaviour of Alumina-Spinel Self-Flowing Castables with Nano-Alumina Particles Addition

The purpose of this study is to determine the influence of nano-alumina particles on the self-flo... more The purpose of this study is to determine the influence of nano-alumina particles on the self-flow characteristics of aluminaspinel self-flowing castables. For this reason, the self-flow characteristics such as; self-flow value and working time of the alumina-spinel castables with different amount of nano-alumina particles have been studied. Also, the mechanical properties and microstructure of these castables have been studied. For the study of nano-alumina (d50 =4 3 nm) addition on selfflow characteristics and other properties of these castables, reactive alumina is substituted by nano-alumina powder in 0-4 wt.% range. The results show that the nano-alumina particles have great effect on the self-flow characteristics and mechanical strength. With increase of nano-alumina particles in castable composition, the self-flow value and working time tends to decrease and cold crushing strength is enhanced at all temperatures. By use of 1.5 wt.% nano-alumina contents in the castable compos...

Research paper thumbnail of Preparation and Characterization of Nanocrystalline Misch-Metal-Substituted Yttrium Iron Garnet Powder by the Sol-Gel Combustion Process

International Journal of Applied Ceramic Technology, Jul 10, 2008

Research paper thumbnail of OXIDATION MECHANISMS IN MgO-C REFRACTORIES

Oxidation of graphite in MgO-C refractories can result in degradation of brick properties (By cre... more Oxidation of graphite in MgO-C refractories can result in degradation of brick properties (By creating porosity and deteriorating the bonding within the structure) and eliminate the effects of graphite in the system and finally shorten the service lifetime of the refractories. Determination of oxidation mechanisms will help to prevent and/or lower the effects of this phenomenon (as a benefit factor

Research paper thumbnail of Synthesis and characterization of nanocrystalline barium strontium titanate

Barium strontium titanate (BST) was prepared via simple sol-gel method by using tetrabutyl titana... more Barium strontium titanate (BST) was prepared via simple sol-gel method by using tetrabutyl titanate, ethanol, citric acid and ethylene glycol as starting materials. Thermogravimetry (TG) and differential thermal analyze (DTA) were used to examine behavior of xerogel. The particle size of BST was near to 21nm calculated by X-Ray diffraction (XRD) and confirmed by transition electron microscopy (TEM) for 750

Research paper thumbnail of Synthesis of pyrochlore free PMN–PZT ceramics via a seeding method

Sensors and Actuators A: Physical, 2008

Research paper thumbnail of Electrothermal simulation of barium titanate based PTCR thermistor

Materials Science and Engineering: B, 2006

Research paper thumbnail of Synthesis of PMN pyrochlore free ceramics via a modified mixed oxide method

Journal of Electroceramics, 2007

Research paper thumbnail of Microstructure and cutting performance investigation of Ti(C, N)-based cermets containing various types of secondary carbides

International Journal of Machine Tools & Manufacture, 2007

In this paper, the effects of type and amount of various secondary carbides on the microstructure... more In this paper, the effects of type and amount of various secondary carbides on the microstructure and cutting performance of Ti(C0.7N0.3)–12Co system have been investigated. Nine alloys with different amounts of WC, Mo2C and Ta0.7Nb0.3C additives were studied, using scanning electron microscopy (SEM), Vickers hardness (HV), transverse rupture strength (TRS) and continuous turning tests. Alloys including Mo2C and WC presented

Research paper thumbnail of Investigation of graphite oxidation kinetics in MgO–C composite via artificial neural network approach

Computational Materials Science, 2007

In this study an artificial neural network (ANN) model was developed to predict the oxidation beh... more In this study an artificial neural network (ANN) model was developed to predict the oxidation behavior of magnesia graphite composites. After mechanism evaluation in different conditions, the kinetic parameters such as effective diffusion coefficient and diffusion activation energy of oxidation were calculated from ANN predicted results at different graphite content. The obtained mechanism and kinetic parameters were compared with experimental data.First of all, the reliability of the model was checked with different available data. It was found that the model results were in good agreement with experimental data prediction.The results showed that the main mechanism of oxidation was pore diffusion and effective diffusion coefficient as well as diffusion activation energy were comparable with previous works.Effective diffusion coefficient and diffusion activation energy which were calculated versus graphite content are in good agreement with experimental values.

Research paper thumbnail of Inclusion of carbon nanotubes in a hydroxyapatite sol–gel matrix

Ceramics International, 2009

Research paper thumbnail of Effects of resin and graphite content on density and oxidation behavior of MgO-C refractory bricks

Ceramics International, 2006

The effects of resin type and content as well as graphite content on physical and mechanical prop... more The effects of resin type and content as well as graphite content on physical and mechanical properties of MgO-C refractories, such as density, porosity and strength were studied. The samples were formulated with various amounts of graphite and resin, and their oxidation behavior was isothermally investigated using a thermo gravimeter (TG), in air and at a temperature ranges from 900

Research paper thumbnail of Oxidation mechanism of C in MgO–C refractory bricks

Research paper thumbnail of The effect of nano-size additives on the electrical conductivity of matrix suspension and properties of self-flowing low-cement high alumina refractory castables

Ceramics International, 2010

Influence of two nano-size additives on electrical properties of suspension matrix of self-flowin... more Influence of two nano-size additives on electrical properties of suspension matrix of self-flowing low-cement high alumina refractory castable is investigated. For this purpose, castament FS 10 and FS 20 on the basis of polycarboxylate ether were considered. The self-flow value, ...

Research paper thumbnail of Study of microstructure and dielectric properties of PMN-PZT ceramics via a mixed powder method including microemulsion derived PZT powder

Malaysian Journal of Microscopy, 2011

ABSTRACT In this research, (X)PZT-(1-X)PMN ceramics (where X is 0.25, 0.5 and 0.75) were achieved... more ABSTRACT In this research, (X)PZT-(1-X)PMN ceramics (where X is 0.25, 0.5 and 0.75) were achieved from a conventional mixed-oxide method. Lead Zirconate titanate (PZT) powders with composition near the morphotropic phase boundary have been synthesized via a microemulsion processing route. Modified mixed oxides method was used for obtaining single phase Lead Magnesium niobate (PMN) powder with high relative density (98% of T.D.) and good electrical properties (dielectric constant of ≈10 4 at room temperature). Two-step sintering (TSS) has been applied to suppress the accelerated grain growth of PZT-PMN composite compacts in the last sintering stage. The produced samples with high PZT content showed low densities due to the low compaction ratio of PZT powder. The dielectric properties of PZT-rich and PMN-rich materials were high (dielectric constant of about 0.7×10 3 and 1×10 3 was measured for PZT-rich and PMN-rich ceramics, respectively) while the other sample exhibited lower dielectric properties. The X-ray diffraction analysis of the sintered samples indicated that PZT-PMN ceramic was produced successfully with traces of pyrochlore phase formed in the structure.

Research paper thumbnail of Photocatalytic activity of TiO2-capped ZnO nanoparticles

Journal of Materials Science: Materials in Electronics, 2011

Abstract Using a combined hydrothermal and sol–gel route, TiO 2-capped ZnO nanoparticles with an ... more Abstract Using a combined hydrothermal and sol–gel route, TiO 2-capped ZnO nanoparticles with an average size of 60 nm were prepared. The titania shell was amorphous with a thickness of~ 10 nm. Formation of Zn 2 TiO 4 phase at higher calcination temperature was noticed. Effects of Ti/Zn molar ratio and coating time on the thickness of TiO 2 shell and the photoactivity of the particles for decolorization of Methylene Blue (MB) under UV lamp irradiation (3 mW/cm 2) were investigated. The nanoparticles were characterized ...

Research paper thumbnail of Preparation and characterization of yttrium iron garnet (YIG) nanocrystalline powders by auto-combustion of nitrate-citrate gel

Journal of Alloys and Compounds, 2007

Research paper thumbnail of Study of microstructure and dielectric properties of PMN–PZT ceramics via a mixed powder method including sol–gel precursor

Journal of Alloys and Compounds, 2009

Research paper thumbnail of Template-directed hydrothermal synthesis of dandelion-like hydroxyapatite in the presence of cetyltrimethylammonium bromide and polyethylene glycol

Ceramics International, 2009

Research paper thumbnail of Effect of Surfactant in Formation of Hydroxyapatite Nano-Rods under Hydrothermal Conditions

Iranian Journal of …, 2008

Research paper thumbnail of Crystallization and electrical properties of V2O5 thin films prepared by RF sputtering

Applied Surface Science, 2007

Research paper thumbnail of Behaviour of Alumina-Spinel Self-Flowing Castables with Nano-Alumina Particles Addition

The purpose of this study is to determine the influence of nano-alumina particles on the self-flo... more The purpose of this study is to determine the influence of nano-alumina particles on the self-flow characteristics of aluminaspinel self-flowing castables. For this reason, the self-flow characteristics such as; self-flow value and working time of the alumina-spinel castables with different amount of nano-alumina particles have been studied. Also, the mechanical properties and microstructure of these castables have been studied. For the study of nano-alumina (d50 =4 3 nm) addition on selfflow characteristics and other properties of these castables, reactive alumina is substituted by nano-alumina powder in 0-4 wt.% range. The results show that the nano-alumina particles have great effect on the self-flow characteristics and mechanical strength. With increase of nano-alumina particles in castable composition, the self-flow value and working time tends to decrease and cold crushing strength is enhanced at all temperatures. By use of 1.5 wt.% nano-alumina contents in the castable compos...

Research paper thumbnail of Preparation and Characterization of Nanocrystalline Misch-Metal-Substituted Yttrium Iron Garnet Powder by the Sol-Gel Combustion Process

International Journal of Applied Ceramic Technology, Jul 10, 2008

Research paper thumbnail of OXIDATION MECHANISMS IN MgO-C REFRACTORIES

Oxidation of graphite in MgO-C refractories can result in degradation of brick properties (By cre... more Oxidation of graphite in MgO-C refractories can result in degradation of brick properties (By creating porosity and deteriorating the bonding within the structure) and eliminate the effects of graphite in the system and finally shorten the service lifetime of the refractories. Determination of oxidation mechanisms will help to prevent and/or lower the effects of this phenomenon (as a benefit factor

Research paper thumbnail of Synthesis and characterization of nanocrystalline barium strontium titanate

Barium strontium titanate (BST) was prepared via simple sol-gel method by using tetrabutyl titana... more Barium strontium titanate (BST) was prepared via simple sol-gel method by using tetrabutyl titanate, ethanol, citric acid and ethylene glycol as starting materials. Thermogravimetry (TG) and differential thermal analyze (DTA) were used to examine behavior of xerogel. The particle size of BST was near to 21nm calculated by X-Ray diffraction (XRD) and confirmed by transition electron microscopy (TEM) for 750

Research paper thumbnail of Synthesis of pyrochlore free PMN–PZT ceramics via a seeding method

Sensors and Actuators A: Physical, 2008

Research paper thumbnail of Electrothermal simulation of barium titanate based PTCR thermistor

Materials Science and Engineering: B, 2006

Research paper thumbnail of Synthesis of PMN pyrochlore free ceramics via a modified mixed oxide method

Journal of Electroceramics, 2007

Research paper thumbnail of Microstructure and cutting performance investigation of Ti(C, N)-based cermets containing various types of secondary carbides

International Journal of Machine Tools & Manufacture, 2007

In this paper, the effects of type and amount of various secondary carbides on the microstructure... more In this paper, the effects of type and amount of various secondary carbides on the microstructure and cutting performance of Ti(C0.7N0.3)–12Co system have been investigated. Nine alloys with different amounts of WC, Mo2C and Ta0.7Nb0.3C additives were studied, using scanning electron microscopy (SEM), Vickers hardness (HV), transverse rupture strength (TRS) and continuous turning tests. Alloys including Mo2C and WC presented

Research paper thumbnail of Investigation of graphite oxidation kinetics in MgO–C composite via artificial neural network approach

Computational Materials Science, 2007

In this study an artificial neural network (ANN) model was developed to predict the oxidation beh... more In this study an artificial neural network (ANN) model was developed to predict the oxidation behavior of magnesia graphite composites. After mechanism evaluation in different conditions, the kinetic parameters such as effective diffusion coefficient and diffusion activation energy of oxidation were calculated from ANN predicted results at different graphite content. The obtained mechanism and kinetic parameters were compared with experimental data.First of all, the reliability of the model was checked with different available data. It was found that the model results were in good agreement with experimental data prediction.The results showed that the main mechanism of oxidation was pore diffusion and effective diffusion coefficient as well as diffusion activation energy were comparable with previous works.Effective diffusion coefficient and diffusion activation energy which were calculated versus graphite content are in good agreement with experimental values.

Research paper thumbnail of Inclusion of carbon nanotubes in a hydroxyapatite sol–gel matrix

Ceramics International, 2009

Research paper thumbnail of Effects of resin and graphite content on density and oxidation behavior of MgO-C refractory bricks

Ceramics International, 2006

The effects of resin type and content as well as graphite content on physical and mechanical prop... more The effects of resin type and content as well as graphite content on physical and mechanical properties of MgO-C refractories, such as density, porosity and strength were studied. The samples were formulated with various amounts of graphite and resin, and their oxidation behavior was isothermally investigated using a thermo gravimeter (TG), in air and at a temperature ranges from 900

Research paper thumbnail of Oxidation mechanism of C in MgO–C refractory bricks

Research paper thumbnail of The effect of nano-size additives on the electrical conductivity of matrix suspension and properties of self-flowing low-cement high alumina refractory castables

Ceramics International, 2010

Influence of two nano-size additives on electrical properties of suspension matrix of self-flowin... more Influence of two nano-size additives on electrical properties of suspension matrix of self-flowing low-cement high alumina refractory castable is investigated. For this purpose, castament FS 10 and FS 20 on the basis of polycarboxylate ether were considered. The self-flow value, ...

Research paper thumbnail of Study of microstructure and dielectric properties of PMN-PZT ceramics via a mixed powder method including microemulsion derived PZT powder

Malaysian Journal of Microscopy, 2011

ABSTRACT In this research, (X)PZT-(1-X)PMN ceramics (where X is 0.25, 0.5 and 0.75) were achieved... more ABSTRACT In this research, (X)PZT-(1-X)PMN ceramics (where X is 0.25, 0.5 and 0.75) were achieved from a conventional mixed-oxide method. Lead Zirconate titanate (PZT) powders with composition near the morphotropic phase boundary have been synthesized via a microemulsion processing route. Modified mixed oxides method was used for obtaining single phase Lead Magnesium niobate (PMN) powder with high relative density (98% of T.D.) and good electrical properties (dielectric constant of ≈10 4 at room temperature). Two-step sintering (TSS) has been applied to suppress the accelerated grain growth of PZT-PMN composite compacts in the last sintering stage. The produced samples with high PZT content showed low densities due to the low compaction ratio of PZT powder. The dielectric properties of PZT-rich and PMN-rich materials were high (dielectric constant of about 0.7×10 3 and 1×10 3 was measured for PZT-rich and PMN-rich ceramics, respectively) while the other sample exhibited lower dielectric properties. The X-ray diffraction analysis of the sintered samples indicated that PZT-PMN ceramic was produced successfully with traces of pyrochlore phase formed in the structure.