S. Mirkazemi - Academia.edu (original) (raw)

Papers by S. Mirkazemi

Materials and Energy Research Center (MERC) Iranian Ceramic Society (ICERS), Jun 1, 2019

Porous Si3N4 ceramics were prepared by a novel colloidal method called starch consolidation casti... more Porous Si3N4 ceramics were prepared by a novel colloidal method called starch consolidation casting. In this method, starch plays both pore-forming and consolidating roles. The effect of starch content on the viscosity of Si3N4/starch slurry was investigated in this research. Rotational Rheometer was used to study the rheological behavior of Si3N4/starch slurry. Green samples with 5 to 10MPa flexural strength were shaped by casting slurries in a nonporous mold and held at 80C for 120min. Afterward the samples burned-out and sintered at 1650C for 4h in an air furnace under a nitride powder bed condition. Thermal behavior, phase evolution, and microstructure of sintered samples were characterized through Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The XRD results showed that β − Si 3 N 4 was the main phase in the sintered samples. The β − Si 3 N 4 phase content was as much as 90wt% in the sintered samples. Finally, a porous silicon nitride sample was successfully produced with 44 vol% open porosity and Flexural strength of 108.9MPa through the starch consolidation casting method.

Iranian Journal of Materials Science and Engineering, 2015

In the present study, the feasibility of α-Fe ferromagnetic phase formation in glass and glass-ce... more In the present study, the feasibility of α-Fe ferromagnetic phase formation in glass and glass-ceramic by reduction in hydrogen atmosphere have been investigated. The glass with the composition of 35Na 2 O–24Fe2O3–20B 2O3 – 20SiO 2 –1ZnO (mol %) was melted and quenched by using a twin roller technique. As quenched glass flakes were heat treated in the range of 400-675 °C for 1-2 h in hydrogen atmosphere, which resulted in reduction of iron cations to α-Fe and FeO. The reduction of iron cations in glass was not completely occurred. Saturation magnetization of these samples was 8-37 emu g -1 . For the formation of glass ceramic, As quenched glass flakes heat treated at 590 °C for 1 h. Heat treatment of glass ceramic containing magnetite at 675°C in hydrogen atmosphere for 1 h led to reduction of almost all of the iron cations to α-Fe. Saturation magnetization of this sample increased from 19.8 emu g -1 for glass ceramic to 67 emu g -1

How to cite this article Single phase BiFeO 3 nanoparticles as a visible light photocatalyst were... more How to cite this article Single phase BiFeO 3 nanoparticles as a visible light photocatalyst were successfully synthesized by thermal decomposition of the glyoxylate precursor. The glyoxylate precursors were formed by the redox reaction between ethylene glycol and nitrate ions. The phase evolution, structure and optical properties of BiFeO 3 nanoparticles were characterized by X-ray diffraction, electron microscopy and UV-Vis spectroscopy methods. The BiFeO 3 nanoparticles showed the quasi spherical shape. The BiFeO 3 nanoparticles synthesized at 500 °C showed the weak ferromagnetism behavior, due to the size confinement effect, in spite of the antiferromagnetic behavior of the BiFeO 3 nanoparticles synthesized at 600 °C. The BiFeO 3 nanoparticles exhibited strong absorption in the visible region with the optical band gap calculated from Tauc's plot. The optical band gap decreased from 2.10 to 2.08 eV by the increasing of thermal decomposition temperature. Moreover, the BiFeO 3 ...

Ceramics International, 2020

Abstract The mineral constituent of the bone contains non-stoichiometric hydroxyapatite with vari... more Abstract The mineral constituent of the bone contains non-stoichiometric hydroxyapatite with various substitutional ions. Iron (Fe) and cobalt (Co) are fundamental cofactors, which influence cell respiration and mitosis, respectively. In this study, undoped, Fe3+-, Co2+-, and dually-doped HA nanoparticles (NPs) were synthesized by the hydrothermal method. The F e + C o C a + F e + C o molar ratio was varied between 0.02 and 0.2. Samples were analyzed using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), vibrating sample magnetometry (VSM), Fourier-transformed infrared spectroscopy (FT-IR), inductively coupled plasma optical emission spectroscopy (ICP-OES), and biological assessment. XRD results confirmed the formation of the hexagonal HA crystal structure. The crystallite size was reduced from 34.6 nm to 4.4 nm. Also, the c-axis dimension and the degree of crystallinity were reduced in all the doped samples. The FESEM results showed a change of morphology from rod-like in the undoped nHA into a sphere-like morphology in the doped-samples. With the addition of ferromagnetic dopant, the magnetic behavior of samples altered from diamagnetic to paramagnetic-like and ferromagnetic behavior. Bioactivity assessment indicated the formation of the HA particle on the surface of all synthesized materials. The antibacterial test demonstrated antibacterial activity against gram-negative (−) E. coli. Moreover, the antibiotic-impregnated samples had a synergistic effect on both gram (−), E. coli, as well as gram (+), S. aureus, bacteria. The MTT evaluation revealed the enhanced cell viability of osteoblast-like cells in the dually-doped NPs. Based on this survey, we can strongly emphasize the potential for bone bioactivity and antibacterial feature of these newly developed samples.

In this research nanoparticles of Ni0.55Zn0.35Cu0.1Fe2O4 were synthesized by sol-gel auto-combust... more In this research nanoparticles of Ni0.55Zn0.35Cu0.1Fe2O4 were synthesized by sol-gel auto-combustion method. Changes in phase constituents, microstructure and magnetic properties as a result of Zn and Cu additions were evaluated by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and Vibration Sample Magnetometer (VSM) techniques. XRD results show that the doped sample have a single phase cubic spinel structure while the undoped sample consists of NiFe2O4, FeNi3, α-Fe2O3 and NiO phases. Changes in cell parameter calculated by MAUD software using XRD patterns showed that the cell parameters of the doped sample had expansion about 0.044 Å. Microstructural studies demonstrated considerable reduction of particle size and particle size distribution in the sample synthesized with dopants. Magnetic measurements have been determined increasing of the saturation magnetization from 36.96emu/g to 56.46emu/g and decreasing of coercivity force from 175.5Oe to 98.79Oe...

Journal of Advanced Materials In Engineering

In this research, nickel ferrite nanoparticles were synthesized by sol-gel auto-combustion route,... more In this research, nickel ferrite nanoparticles were synthesized by sol-gel auto-combustion route, and the effect of calcination temperature on phase constituents, magnetic properties and microstructure of the synthesized nanoparticles was evaluated using X-ray Diffraction (XRD), Vibrating Sample Magnetometer (VSM) and Scanning Electron Microscopy (SEM). XRD results were submitted to quantitative analysis. Microstructural studies and crystallite size calculations showed formation of nanoparticles. XRD results showed that the combustion product consisted of NiFe2O4, α-Fe2O3, NiO, and FeNi3 phases. FeNi3 was eliminated by calcination, and the amounts of NiO and α-Fe2O3 were modvlated by changing in calcination temperature. Saturation magnetization changed from 37emu/g in combustion product to 30emu/g by calcination at 600°C, due to decomposition of FeNi3 magnetic phase and formation of higher amount of antiferromagnetic hematite phase. Also, the

International Journal of NanoScience and Nanotechnology, 2016

In this research nanoparticles of Ni0.55Zn0.35Cu0.1Fe2O4 were synthesized by sol–gel auto-combust... more In this research nanoparticles of Ni0.55Zn0.35Cu0.1Fe2O4 were synthesized by sol–gel auto-combustion method. Changes in phase constituents, microstructure and magnetic properties as a result of Zn and Cu additions were evaluated by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and Vibration Sample Magnetometer (VSM) techniques. XRD results show that the doped sample have a single phase cubic spinel structure while the undoped sample consists of NiFe2O4, FeNi3, α-Fe2O3 and NiO phases. Changes in cell parameter calculated by MAUD software using XRD patterns showed that the cell parameters of the doped sample had expansion about 0.044 A. Microstructural studies demonstrated considerable reduction of particle size and particle size distribution in the sample synthesized with dopants. Magnetic measurements have been determined increasing of the saturation magnetization from 36.96emu/g to 56.46emu/g and decreasing of coercivity force from 175.5Oe to 98.79Oe...

Flash sintering has been investigated as a modern sintering method through examining the effect o... more Flash sintering has been investigated as a modern sintering method through examining the effect of processing parameters such as current density, temperature, and contact paste on the flash sintered 8YSZ characteristic. 95% of theoretical density was achieved at 800°С in 30sec with a field intensity of 100V.cm-1 and a current density of 160mA.mm-2. Such relative density in conventional sintering achieved at 1450°С for 4 hours. Results indicated that the temperature and flash current density have positive effects on the relative density. Contact paste had a significant effect on the relative density. 8YSZ samples with LSM contact paste had a higher relative density in comparison with those flash sintered with Pt contact paste. The positive effect of LSM contact paste was more significant, especially at lower current density.

In this research, nano-sized powders of Zr–Mn substituted strontium hexaferrite (Sr(Zr,Mn)xFe12−2... more In this research, nano-sized powders of Zr–Mn substituted strontium hexaferrite (Sr(Zr,Mn)xFe12−2xO19 (x = 0, 2, 2.5, 3)) were synthesized by sol–gel auto-combustion route using subsequent heat treatment. The samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), Mössbauer spectroscopy and vibration sample magnetometer (VSM) techniques. XRD and Mössbauer spectroscopy results revealed formation of Sr(Zr,Mn)xFe12−2xO19 accompanied with MnδFe2−δO4 lateral phase in the samples. Also, FTIR and XRD results demonstrated presence of SrO impurity phase. FESEM micrographs show particle size reduction and presence of two distinct powder morphologies with different brightness levels with Zr4+ and Mn2+ substitutions which approves existence of lateral phases in the substituted samples. TEM micrographs show nanometric particles with sizes smaller than 100...

Glass Physics and Chemistry, 2021

This work aims to study the effect of sodium silicate additive on the microstructure and physical... more This work aims to study the effect of sodium silicate additive on the microstructure and physical properties of foam glass fabricated from the recycled soda–lime glass regarding the process temperature of 700 to 900°C. Sodium silicate was added as a cost-effective environmental foaming agent in 10 to 30 wt % to recycled soda–lime glass powder (maximum size of 63 μm), pressed and heat-treated for 30 min. X-ray diffraction, scanning electron microscopy, and thermogravimetry analysis were used to characterize the phase evolution, porosity, morphology, and the foam-forming ability, respectively. Bulk and true density, as well as flexural strength, were measured. The results showed that for samples containing 20 wt % water glass treated at 800°C, bulk density and strength values was 0.54 g/cm3 and 5.3 ± 0.7 MPa, Theses samples have higher strength than commercial foam glasses with uniformly distributed pores of 66.67% confirmed by the SEM images.

In this investigation, the effect of heat treatment on magnetic properties of glass and nano-stru... more In this investigation, the effect of heat treatment on magnetic properties of glass and nano-structured cobalt-ferrite glass-ceramic was studied. The glass was synthesized in the system of Na2O-Fe2O3-CoO-B2O3-SiO2. Based on DTA results, heat treatment was done at different times and temperatures. X-ray diffraction pattern of glass-ceramic showed the crystallization * یکینورتکلا تسپ ،تابتاکم لوئسم : mirkazemi@iust.ac.ir D ow nl oa de d fr om ja m e. iu t.a c. ir at 2 1: 50 IR S T o n F rid ay D ec em be r 14 th 2 01 8 [ D O I: 10 .1 88 69 /a ca dp ub .ja m e. 34 .2 .6 1 ]

In this study, an attempt has been made to study the effect of Bi2O3 addition as nucleating agent... more In this study, an attempt has been made to study the effect of Bi2O3 addition as nucleating agent on the liquid-liquid phase separation, crystallization and dielectric properties of samples prepared by sintering and crystallization of powdered glass in PbO-TiO2-B2O3-SiO2 glass-ceramic system using DTA, XRD, SEM and LCR techniques. The results showed that the addition of Bi2O3 resulted in a quite distinct liquidliquid phase separation, i.e. spinodal decomposition, in as-quenched glass samples with significant effects on the nucleation and crystallization process. Glass ribbons were heat treated at 630-557 °C for different lengths of time. Based on the results obtained, it was shown that the addition of Bi2O3 promotes the crystallization of PbTiO3. The dielectric constant (er) increased in all heat-treated samples with increasing time except for the sample heat treated for 5 hr for which er, decreased. This behavior was attributed to the formation of PT-Bi2O3 solid solution. The diele...

Optics and Photonics Society of Iran, 2015

Semiconductor lasers play an important role in free space optical communications for capability o... more Semiconductor lasers play an important role in free space optical communications for capability of direct modulation and changing the power by changing the current. The changes of current and temperature of the system alter the wavelength and these changes affect the optical receiver system design and in particular its filters. In this article, wavelength chirping of semiconductor laser due to changes in current and temperature have been measured. Based on the range of variation, suitable combined filter consisting of a low pass filter and high pass filter was selected. The measurement results are presented using graphs and charts.

Iranian Journal of Materials Science and Engineering, 2015

The effects of temperature, time and atmosphere on microstructure and magnetic properties of NiFe... more The effects of temperature, time and atmosphere on microstructure and magnetic properties of NiFe2O4 glassceramic were investigated utilizing differential thermal analysis, X-ray diffraction, vibrating sample magnetometer and scanning electron microscope techniques. Various compositions were studied in the Na2O-NiO-Fe2O3-B2O3-SiO2 system to obtain amorphous phase. The sample heat-treated in graphite bed at 510C for 1 hr showed higher magnetization than the one heattreated in the air under the same condition. XRD analysis showed the presence of nickel ferrite and some non-magnetic phases such as sodium borate and silicate phases in the heat treated samples. The maximum magnetization of samples reduced by increasing the holding time from 1hr to 3 hr at 510C. Increment of temperature to 700C increased the amount of NiFe2O4 and maximum magnetization.

The materials with spinel structures are important for their unique structural and physical prope... more The materials with spinel structures are important for their unique structural and physical properties. In the current research, nanocrystalline hercynite was synthesized using metal nitrates and a polymer matrix precursor composed of sucrose and polyvinyl alcohol (PVA) via sol-gel process. The gel was dried and then the precursor was preheated at1000C in the air atmosphere and then calcined at different temperatures in the reducing atmosphere in the graphite bed. The preheated and calcined powders were characterized using simultaneous thermal analysis, X-ray diffraction (XRD) and field emission scanning electron microscopy(SEM). Results showed that fully * : يکينورتکلا تسپ تابتاکم لوئسم : hsarpoolaky@iust.ac.ir D ow nl oa de d fr om ja m e. iu t.a c. ir at 8 :5 7 IR S T o n T ue sd ay J an ua ry 2 1s t 2 02 0

Porous Si3N4 ceramics were prepared by a novel colloidal method called starch consolidation casti... more Porous Si3N4 ceramics were prepared by a novel colloidal method called starch consolidation casting. In this method, starch plays both pore-forming and consolidating roles. The effect of starch content on the viscosity of Si3N4/starch slurry was investigated in this research. Rotational Rheometer was used to study the rheological behavior of Si3N4/starch slurry. Green samples with 5 to 10MPa flexural strength were shaped by casting slurries in a nonporous mold and held at 80°C for 120min. Afterward the samples burned-out and sintered at 1650°C for 4h in an air furnace under a nitride powder bed condition. Thermal behavior, phase evolution, and microstructure of sintered samples were characterized through Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The XRD results showed that was the main phase in the sintered samples. The phase content was as much as 90wt% in the sintered samples. Finally, a porous silicon nitride sample was su...

The effects of temperature, time and atmosphere on microstructure and magnetic properties of NiFe... more The effects of temperature, time and atmosphere on microstructure and magnetic properties of NiFe2O4 glassceramic were investigated utilizing differential thermal analysis, X-ray diffraction, vibrating sample magnetometer and scanning electron microscope techniques. Various compositions were studied in the Na2O-NiO-Fe2O3-B2O3-SiO2 system to obtain amorphous phase. The sample heat-treated in graphite bed at 510C for 1 hr showed higher magnetization than the one heattreated in the air under the same condition. XRD analysis showed the presence of nickel ferrite and some non-magnetic phases such as sodium borate and silicate phases in the heat treated samples. The maximum magnetization of samples reduced by increasing the holding time from 1hr to 3 hr at 510C. Increment of temperature to 700C increased the amount of NiFe2O4 and maximum magnetization.

Materials and Energy Research Center (MERC) Iranian Ceramic Society (ICERS), Jun 1, 2019

Porous Si3N4 ceramics were prepared by a novel colloidal method called starch consolidation casti... more Porous Si3N4 ceramics were prepared by a novel colloidal method called starch consolidation casting. In this method, starch plays both pore-forming and consolidating roles. The effect of starch content on the viscosity of Si3N4/starch slurry was investigated in this research. Rotational Rheometer was used to study the rheological behavior of Si3N4/starch slurry. Green samples with 5 to 10MPa flexural strength were shaped by casting slurries in a nonporous mold and held at 80C for 120min. Afterward the samples burned-out and sintered at 1650C for 4h in an air furnace under a nitride powder bed condition. Thermal behavior, phase evolution, and microstructure of sintered samples were characterized through Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The XRD results showed that β − Si 3 N 4 was the main phase in the sintered samples. The β − Si 3 N 4 phase content was as much as 90wt% in the sintered samples. Finally, a porous silicon nitride sample was successfully produced with 44 vol% open porosity and Flexural strength of 108.9MPa through the starch consolidation casting method.

Iranian Journal of Materials Science and Engineering, 2015

In the present study, the feasibility of α-Fe ferromagnetic phase formation in glass and glass-ce... more In the present study, the feasibility of α-Fe ferromagnetic phase formation in glass and glass-ceramic by reduction in hydrogen atmosphere have been investigated. The glass with the composition of 35Na 2 O–24Fe2O3–20B 2O3 – 20SiO 2 –1ZnO (mol %) was melted and quenched by using a twin roller technique. As quenched glass flakes were heat treated in the range of 400-675 °C for 1-2 h in hydrogen atmosphere, which resulted in reduction of iron cations to α-Fe and FeO. The reduction of iron cations in glass was not completely occurred. Saturation magnetization of these samples was 8-37 emu g -1 . For the formation of glass ceramic, As quenched glass flakes heat treated at 590 °C for 1 h. Heat treatment of glass ceramic containing magnetite at 675°C in hydrogen atmosphere for 1 h led to reduction of almost all of the iron cations to α-Fe. Saturation magnetization of this sample increased from 19.8 emu g -1 for glass ceramic to 67 emu g -1

How to cite this article Single phase BiFeO 3 nanoparticles as a visible light photocatalyst were... more How to cite this article Single phase BiFeO 3 nanoparticles as a visible light photocatalyst were successfully synthesized by thermal decomposition of the glyoxylate precursor. The glyoxylate precursors were formed by the redox reaction between ethylene glycol and nitrate ions. The phase evolution, structure and optical properties of BiFeO 3 nanoparticles were characterized by X-ray diffraction, electron microscopy and UV-Vis spectroscopy methods. The BiFeO 3 nanoparticles showed the quasi spherical shape. The BiFeO 3 nanoparticles synthesized at 500 °C showed the weak ferromagnetism behavior, due to the size confinement effect, in spite of the antiferromagnetic behavior of the BiFeO 3 nanoparticles synthesized at 600 °C. The BiFeO 3 nanoparticles exhibited strong absorption in the visible region with the optical band gap calculated from Tauc's plot. The optical band gap decreased from 2.10 to 2.08 eV by the increasing of thermal decomposition temperature. Moreover, the BiFeO 3 ...

Ceramics International, 2020

Abstract The mineral constituent of the bone contains non-stoichiometric hydroxyapatite with vari... more Abstract The mineral constituent of the bone contains non-stoichiometric hydroxyapatite with various substitutional ions. Iron (Fe) and cobalt (Co) are fundamental cofactors, which influence cell respiration and mitosis, respectively. In this study, undoped, Fe3+-, Co2+-, and dually-doped HA nanoparticles (NPs) were synthesized by the hydrothermal method. The F e + C o C a + F e + C o molar ratio was varied between 0.02 and 0.2. Samples were analyzed using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), vibrating sample magnetometry (VSM), Fourier-transformed infrared spectroscopy (FT-IR), inductively coupled plasma optical emission spectroscopy (ICP-OES), and biological assessment. XRD results confirmed the formation of the hexagonal HA crystal structure. The crystallite size was reduced from 34.6 nm to 4.4 nm. Also, the c-axis dimension and the degree of crystallinity were reduced in all the doped samples. The FESEM results showed a change of morphology from rod-like in the undoped nHA into a sphere-like morphology in the doped-samples. With the addition of ferromagnetic dopant, the magnetic behavior of samples altered from diamagnetic to paramagnetic-like and ferromagnetic behavior. Bioactivity assessment indicated the formation of the HA particle on the surface of all synthesized materials. The antibacterial test demonstrated antibacterial activity against gram-negative (−) E. coli. Moreover, the antibiotic-impregnated samples had a synergistic effect on both gram (−), E. coli, as well as gram (+), S. aureus, bacteria. The MTT evaluation revealed the enhanced cell viability of osteoblast-like cells in the dually-doped NPs. Based on this survey, we can strongly emphasize the potential for bone bioactivity and antibacterial feature of these newly developed samples.

In this research nanoparticles of Ni0.55Zn0.35Cu0.1Fe2O4 were synthesized by sol-gel auto-combust... more In this research nanoparticles of Ni0.55Zn0.35Cu0.1Fe2O4 were synthesized by sol-gel auto-combustion method. Changes in phase constituents, microstructure and magnetic properties as a result of Zn and Cu additions were evaluated by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and Vibration Sample Magnetometer (VSM) techniques. XRD results show that the doped sample have a single phase cubic spinel structure while the undoped sample consists of NiFe2O4, FeNi3, α-Fe2O3 and NiO phases. Changes in cell parameter calculated by MAUD software using XRD patterns showed that the cell parameters of the doped sample had expansion about 0.044 Å. Microstructural studies demonstrated considerable reduction of particle size and particle size distribution in the sample synthesized with dopants. Magnetic measurements have been determined increasing of the saturation magnetization from 36.96emu/g to 56.46emu/g and decreasing of coercivity force from 175.5Oe to 98.79Oe...

Journal of Advanced Materials In Engineering

In this research, nickel ferrite nanoparticles were synthesized by sol-gel auto-combustion route,... more In this research, nickel ferrite nanoparticles were synthesized by sol-gel auto-combustion route, and the effect of calcination temperature on phase constituents, magnetic properties and microstructure of the synthesized nanoparticles was evaluated using X-ray Diffraction (XRD), Vibrating Sample Magnetometer (VSM) and Scanning Electron Microscopy (SEM). XRD results were submitted to quantitative analysis. Microstructural studies and crystallite size calculations showed formation of nanoparticles. XRD results showed that the combustion product consisted of NiFe2O4, α-Fe2O3, NiO, and FeNi3 phases. FeNi3 was eliminated by calcination, and the amounts of NiO and α-Fe2O3 were modvlated by changing in calcination temperature. Saturation magnetization changed from 37emu/g in combustion product to 30emu/g by calcination at 600°C, due to decomposition of FeNi3 magnetic phase and formation of higher amount of antiferromagnetic hematite phase. Also, the

International Journal of NanoScience and Nanotechnology, 2016

In this research nanoparticles of Ni0.55Zn0.35Cu0.1Fe2O4 were synthesized by sol–gel auto-combust... more In this research nanoparticles of Ni0.55Zn0.35Cu0.1Fe2O4 were synthesized by sol–gel auto-combustion method. Changes in phase constituents, microstructure and magnetic properties as a result of Zn and Cu additions were evaluated by X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), and Vibration Sample Magnetometer (VSM) techniques. XRD results show that the doped sample have a single phase cubic spinel structure while the undoped sample consists of NiFe2O4, FeNi3, α-Fe2O3 and NiO phases. Changes in cell parameter calculated by MAUD software using XRD patterns showed that the cell parameters of the doped sample had expansion about 0.044 A. Microstructural studies demonstrated considerable reduction of particle size and particle size distribution in the sample synthesized with dopants. Magnetic measurements have been determined increasing of the saturation magnetization from 36.96emu/g to 56.46emu/g and decreasing of coercivity force from 175.5Oe to 98.79Oe...

Flash sintering has been investigated as a modern sintering method through examining the effect o... more Flash sintering has been investigated as a modern sintering method through examining the effect of processing parameters such as current density, temperature, and contact paste on the flash sintered 8YSZ characteristic. 95% of theoretical density was achieved at 800°С in 30sec with a field intensity of 100V.cm-1 and a current density of 160mA.mm-2. Such relative density in conventional sintering achieved at 1450°С for 4 hours. Results indicated that the temperature and flash current density have positive effects on the relative density. Contact paste had a significant effect on the relative density. 8YSZ samples with LSM contact paste had a higher relative density in comparison with those flash sintered with Pt contact paste. The positive effect of LSM contact paste was more significant, especially at lower current density.

In this research, nano-sized powders of Zr–Mn substituted strontium hexaferrite (Sr(Zr,Mn)xFe12−2... more In this research, nano-sized powders of Zr–Mn substituted strontium hexaferrite (Sr(Zr,Mn)xFe12−2xO19 (x = 0, 2, 2.5, 3)) were synthesized by sol–gel auto-combustion route using subsequent heat treatment. The samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), Mössbauer spectroscopy and vibration sample magnetometer (VSM) techniques. XRD and Mössbauer spectroscopy results revealed formation of Sr(Zr,Mn)xFe12−2xO19 accompanied with MnδFe2−δO4 lateral phase in the samples. Also, FTIR and XRD results demonstrated presence of SrO impurity phase. FESEM micrographs show particle size reduction and presence of two distinct powder morphologies with different brightness levels with Zr4+ and Mn2+ substitutions which approves existence of lateral phases in the substituted samples. TEM micrographs show nanometric particles with sizes smaller than 100...

Glass Physics and Chemistry, 2021

This work aims to study the effect of sodium silicate additive on the microstructure and physical... more This work aims to study the effect of sodium silicate additive on the microstructure and physical properties of foam glass fabricated from the recycled soda–lime glass regarding the process temperature of 700 to 900°C. Sodium silicate was added as a cost-effective environmental foaming agent in 10 to 30 wt % to recycled soda–lime glass powder (maximum size of 63 μm), pressed and heat-treated for 30 min. X-ray diffraction, scanning electron microscopy, and thermogravimetry analysis were used to characterize the phase evolution, porosity, morphology, and the foam-forming ability, respectively. Bulk and true density, as well as flexural strength, were measured. The results showed that for samples containing 20 wt % water glass treated at 800°C, bulk density and strength values was 0.54 g/cm3 and 5.3 ± 0.7 MPa, Theses samples have higher strength than commercial foam glasses with uniformly distributed pores of 66.67% confirmed by the SEM images.

In this investigation, the effect of heat treatment on magnetic properties of glass and nano-stru... more In this investigation, the effect of heat treatment on magnetic properties of glass and nano-structured cobalt-ferrite glass-ceramic was studied. The glass was synthesized in the system of Na2O-Fe2O3-CoO-B2O3-SiO2. Based on DTA results, heat treatment was done at different times and temperatures. X-ray diffraction pattern of glass-ceramic showed the crystallization * یکینورتکلا تسپ ،تابتاکم لوئسم : mirkazemi@iust.ac.ir D ow nl oa de d fr om ja m e. iu t.a c. ir at 2 1: 50 IR S T o n F rid ay D ec em be r 14 th 2 01 8 [ D O I: 10 .1 88 69 /a ca dp ub .ja m e. 34 .2 .6 1 ]

In this study, an attempt has been made to study the effect of Bi2O3 addition as nucleating agent... more In this study, an attempt has been made to study the effect of Bi2O3 addition as nucleating agent on the liquid-liquid phase separation, crystallization and dielectric properties of samples prepared by sintering and crystallization of powdered glass in PbO-TiO2-B2O3-SiO2 glass-ceramic system using DTA, XRD, SEM and LCR techniques. The results showed that the addition of Bi2O3 resulted in a quite distinct liquidliquid phase separation, i.e. spinodal decomposition, in as-quenched glass samples with significant effects on the nucleation and crystallization process. Glass ribbons were heat treated at 630-557 °C for different lengths of time. Based on the results obtained, it was shown that the addition of Bi2O3 promotes the crystallization of PbTiO3. The dielectric constant (er) increased in all heat-treated samples with increasing time except for the sample heat treated for 5 hr for which er, decreased. This behavior was attributed to the formation of PT-Bi2O3 solid solution. The diele...

Optics and Photonics Society of Iran, 2015

Semiconductor lasers play an important role in free space optical communications for capability o... more Semiconductor lasers play an important role in free space optical communications for capability of direct modulation and changing the power by changing the current. The changes of current and temperature of the system alter the wavelength and these changes affect the optical receiver system design and in particular its filters. In this article, wavelength chirping of semiconductor laser due to changes in current and temperature have been measured. Based on the range of variation, suitable combined filter consisting of a low pass filter and high pass filter was selected. The measurement results are presented using graphs and charts.

Iranian Journal of Materials Science and Engineering, 2015

The effects of temperature, time and atmosphere on microstructure and magnetic properties of NiFe... more The effects of temperature, time and atmosphere on microstructure and magnetic properties of NiFe2O4 glassceramic were investigated utilizing differential thermal analysis, X-ray diffraction, vibrating sample magnetometer and scanning electron microscope techniques. Various compositions were studied in the Na2O-NiO-Fe2O3-B2O3-SiO2 system to obtain amorphous phase. The sample heat-treated in graphite bed at 510C for 1 hr showed higher magnetization than the one heattreated in the air under the same condition. XRD analysis showed the presence of nickel ferrite and some non-magnetic phases such as sodium borate and silicate phases in the heat treated samples. The maximum magnetization of samples reduced by increasing the holding time from 1hr to 3 hr at 510C. Increment of temperature to 700C increased the amount of NiFe2O4 and maximum magnetization.

The materials with spinel structures are important for their unique structural and physical prope... more The materials with spinel structures are important for their unique structural and physical properties. In the current research, nanocrystalline hercynite was synthesized using metal nitrates and a polymer matrix precursor composed of sucrose and polyvinyl alcohol (PVA) via sol-gel process. The gel was dried and then the precursor was preheated at1000C in the air atmosphere and then calcined at different temperatures in the reducing atmosphere in the graphite bed. The preheated and calcined powders were characterized using simultaneous thermal analysis, X-ray diffraction (XRD) and field emission scanning electron microscopy(SEM). Results showed that fully * : يکينورتکلا تسپ تابتاکم لوئسم : hsarpoolaky@iust.ac.ir D ow nl oa de d fr om ja m e. iu t.a c. ir at 8 :5 7 IR S T o n T ue sd ay J an ua ry 2 1s t 2 02 0

Porous Si3N4 ceramics were prepared by a novel colloidal method called starch consolidation casti... more Porous Si3N4 ceramics were prepared by a novel colloidal method called starch consolidation casting. In this method, starch plays both pore-forming and consolidating roles. The effect of starch content on the viscosity of Si3N4/starch slurry was investigated in this research. Rotational Rheometer was used to study the rheological behavior of Si3N4/starch slurry. Green samples with 5 to 10MPa flexural strength were shaped by casting slurries in a nonporous mold and held at 80°C for 120min. Afterward the samples burned-out and sintered at 1650°C for 4h in an air furnace under a nitride powder bed condition. Thermal behavior, phase evolution, and microstructure of sintered samples were characterized through Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The XRD results showed that was the main phase in the sintered samples. The phase content was as much as 90wt% in the sintered samples. Finally, a porous silicon nitride sample was su...

The effects of temperature, time and atmosphere on microstructure and magnetic properties of NiFe... more The effects of temperature, time and atmosphere on microstructure and magnetic properties of NiFe2O4 glassceramic were investigated utilizing differential thermal analysis, X-ray diffraction, vibrating sample magnetometer and scanning electron microscope techniques. Various compositions were studied in the Na2O-NiO-Fe2O3-B2O3-SiO2 system to obtain amorphous phase. The sample heat-treated in graphite bed at 510C for 1 hr showed higher magnetization than the one heattreated in the air under the same condition. XRD analysis showed the presence of nickel ferrite and some non-magnetic phases such as sodium borate and silicate phases in the heat treated samples. The maximum magnetization of samples reduced by increasing the holding time from 1hr to 3 hr at 510C. Increment of temperature to 700C increased the amount of NiFe2O4 and maximum magnetization.