Kajian Kesan Mikrostruktur Yang Berbeza Terhadap Sifat Dielektrik Cacu3ti4o12 [TK7871.15.C4 J94 2008 f rb].

CCTO merupakan bahan elektroseramik yang mempunyai nilai pemalar dielektrik yang sangat tinggi. Kajian dilakukan bagi mengkaji kesan mikrostruktur yang berbeza ke atas sifat dielektrik CCTO seterusnya mengkaji faktor yang menyumbang kepada nilai pemalar dielektrik yang sangat luar biasa ini. CCTO is an electroceramic material that has a very high dielectric constant. A research was carried out to study the effect of different microstructure on dielectric properties of CCTO, hence to investigate the factor that contributes to the extraordinary CCTO properties

Penghasilan Dan Pencirian Komposit Matriks Zn Diperkuat Partikel SiC Melalui Kaedah Metalurgi Serbuk. [TA418.9.C6 J94 2003 f rb] [Microfiche 7546]

Komposit matriks Zn terdiri daripada matriks logam/aloi Zn yang diperkuat samada dengan partikel atau gentian seramik. Zn matrix composite consists of Zn metal/alloys reinforced either with ceramic particle or fibre

Effect of Calcination Temperature on Dielectric Properties of CaCu3Ti4O12 Ceramics

AbstractThe effect of calcination temperature on the properties of CaCu3Ti4O12 (CCTO) ceramics was studied. CCTO ceramics were prepared using solid state reaction method. The raw materials of CCTO were wet mixed for 24 hours and was dried overnight. CCTO powders were then calcined at three different temperature which is at 900̊C, 930̊C and 985̊C for 12 hours. The calcined powders were compacted at 250 MPa and then were sintered at 1040̊C for 10 hours. X-Ray Diffractometer (XRD) analysis showed the formation of CCTO phase and secondary phases of CuO for C900 calcined powder but single phase of CCTO was obtained by C930 and C985 calcined powders. Single phase of CCTO also were seen for all sintered samples. Observation on Scanning Electron Microscopy (SEM) micrographs showed abnormal grain growth or large grain size was seen in C900 sample and finer grain size was observed for C930 and C985 sintered samples. C900 sintered sample obtained the highest dielectric constant (10,462) and the lowest dielectric loss (0.061) measured at 1 MHz

The Effect of Sintering Conditions on the Microstructure and Electrical Properties of Pb(Zr0.52Ti0.48)O3 Ceramic

Lead zirconatetitanate Pb(Zr0.52Ti0.48)O3, (PZT) from a mixture of commercial PbO, TiO2 and ZrO2 powders was successfully prepared using a planetary ball mill. The microstructure and electrical properties of PZT ceramic were found to be highly sensitive to the sintering condition. The influence of microstructure and electrical properties on the sintering condition of the samples was studied. SEM analysis indicated that a shorter sintering time with higher sintering temperature promotes fine structure and densification. This was proves where the relative density of the sintered PZT ceramics obtained was measured to be approximately 99% of the theoretical density. The electrical properties of the ceramic sintered at a higher temperature with a different sintering time were measured at high frequencies. The result revealed that different sintering conditions have a big impact on electrical behavior in a broad frequency region

The effects of different pyrolysis and annealing temperature on structural and resistivity of K0.5Na0.5NbO3 thin film

Potassium sodium niobate (KNN) thin film is a very promising candidate for piezoelectric applications such as for the usage in wireless sensor, actuator, and transducer. In this paper, a low-cost sol-gel spin coating technique was employed to fabricate KNN thin films on silicon (Si) substrate. The effect of pyrolysis and annealing temperature on the material properties of KNN thin films were investigated. X-ray diffraction (XRD), Raman spectroscopy and field emission scanning electron microscopy (FESEM) were used to examine the structural properties of the KNN thin films. The electrical properties of KNN thin films were characterized using resistivity testing. The experimental results reveal that high pyrolysis and annealing temperature greatly enhanced the structural and electrical properties of KNN thin films

Effects of CIP compaction pressure on piezoelectric properties of K0.5Na0.5NbO3

The effects of cold isostatic press (CIP) compaction pressures (100–350 MPa) on the piezoelectric properties of K0.5Na0.5NbO3 (KNN) samples prepared as lead-free piezoelectric ceramic was investigated. The calcined powder of KNN samples were pressed at a pressure of 100 MPa using a hand press to produce green body pallets followed by compacting using the CIP. Pelleted samples were placed in a closed alumina crucible prior to sintering at 1080 °C for 2 h in air atmosphere. The sintered pellets underwent poling process at 120 °C in silicon oil and poling electric field of 4.0 kV mm−1 for 15 min to facilitate the measurement of piezoelectric properties. The results show that both d33 (piezoelectric charge coefficients) and kp (piezoelectric coupling factor) were affected by the variation in CIP compaction pressure. Increasing CIP compaction pressure induced the split of (100) and (110) peaks which attributed to the structural phase transition from orthorhombic phase to tetragonal as shown by XRD analysis. This transition is responsible for the enhancement of their piezoelectric properties with the optimum value obtained from sample CIPped at 300 MPa (d33 = 138 pC N−1, kp = 0.36, ρ = 4.47 g cm−3). The sample also shows smaller grain size (1.0–2.5 µm) and dielectric properties (ɛr = 475 and tan δ = 0.42)

Effect of the Different Sr Dopant Contents on NiO Ceramic

AbstractSr - doped NiO ceramic was studied. The effect of composition variation of Ni(1-x)SrxO where x = 0, 0.01, 0.02, 0.03, 0.05 and 0.10 mole % was prepared by using solid state method. The calcination temperature used at 950°C for 4hours and the sintering temperature used at 1200°C for 3hours. The results depict the microstructures increase in grains size (0.43 - 3.30μm) by increase of Sr dopant contents. The density and porosity testing support the result of microstructures analysis. The larger grains size led to increase in density and lower in porosity. The dielectric properties is observed in a wide frequency range of (1 - 1 000MHz). The increase of dielectric constant is associated with the decrease of dielectric loss. The optimum composition was obtained for the x = 0.03 mole % sample with highest dielectric constant (3.24 x 103) and lowest dielectric loss (1.42) at 1MHz

EFFECT OF DIFFERENT COMPACTION PRESSURE AND DIFFERENT SINTERING ROUTE ON K0.5NA0.5NBO₃ PHYSICAL AND DIELECTRIC PROPERTIES

Alkaline niobate known as K0.5Na0.5NbO3 (KNN), a lead-free piezoelectric ceramic was synthesized via a solid state reaction method. The samples were compacted at different pressures (100, 200, 300 and 400 MPa) and sintered using two different techniques (conventional furnace and hot isostatic pressing (HIP)). The effect of compaction pressure and sintering technique on physical and dielectric properties was studied. The optimum compaction pressure (300 MPa) and sintering via HIP (at 1080 °C for 30 min) increased the density and grain size ( range 30 - 300 nm) and improved its dielectric properties. Therefore, the combination of suitable compaction pressure and sintering technique has produced larger grain size and higher density of KNN which resulted in outstanding dielectric properties. At room temperature, excellent values of ε r (5517.35) and tan δ (0.954), recorded at 1 MHz were measured for the KNN300HIP sample with highest density (4.4885 g/cm³)

Effective dielectric loss (tan δ) reduction of CaCu3Ti4O12 (CCTO) via various addition of glasses

Addition of various glasses has successfully reduced tan δ of CCTO‐based ceramics. Less amounts (0‐1.0 wt%) of glasses (BaO‐SrO‐Nb2O5‐B2O3‐SiO2 [BSNBS] and SrO‐B2O3‐SiO2 [SBS], respectively) were added into pure CCTO and sintered at 1040°C for 10 hours. The phase formation and microstructure of each sample were characterized using X‐ray diffraction and scanning electron microscopy, respectively. The dielectric behavior of the samples was measured at 1 MHz. The addition of BSNBS and SBS glasses (≤0.5 wt%) successfully reduced tan δ of CCTO from 0.5 until 0.4 and 0.39, respectively, and simultaneously increased εr. Smaller tan δ and ɛr were further obtained when the added glasses were more than 0.5 wt%. These behaviors were due to segregation of glasses together with precipitation of CuO which decreased the grain size, and caused the presence of pores at grain boundaries. Therefore, small amount of various additions of glasses could modify the CCTO dielectric properties