Zhixiong Huang

Microstructure and Ferroelectric Properties of (Bi0.9Ho0.1)3.999Ti2.997V0.003O12 Thin Films Prepared by Sol-gel Method for Nonvolatile Memory

The (Bi 0.9 Ho 0.1 ) 3.999 Ti 2.997 V 0.003 O 12 (BHTV) films have been prepared on Pt/Ti/SiO 2 /Si substrates by solgel method. The microstructure and ferroelectric properties of the BHTV films were investigated. The BHTV films show a single phase of Bi-layered Aurivillius structure and dense microstructure. The Ho 3+ /V 5+ co-substitution can effectively improve the ferroelectric properties. The BHTV film exhibits good ferroelectric properties with 2 P r of 47.6°C/cm 2 , 2 E c of 265 kV/cm (at applied field of 420 kV/cm), dielectric constant of 305, dielectric loss of 0.031 (at 1 MHz), good insulting behavior, as well as the fatigue-free behavior.

Preparation and thermal stability of boron-containing phenolic resin/microcrystalline muscovite composites

Abstract In order to further improve thermal stability of the boron-modified phenolic resin, we combined boron-modified phenolic resin and microcrystalline muscovite over a range of microcrystalline muscovite loadings (5–20 wt-%) to prepare composites. Microcrystalline muscovite was modified by titanate coupling agent. Fourier transmission-infrared analysis showed that the titanate coupling agent chemically bonded with the microcrystalline muscovite powder. The modified microcrystalline muscovite was mixed with boron-modified phenolic resin matrix in the molten state, and the composites were cured by compression moulding. Thermogravimetric analysis showed the effect of microcrystalline muscovite content to enhance decomposition temperatures and residual weight at 1000°C of the composites. Flexural test showed that the flexural strength before heat-treated was reduced with incremental loadings of microcrystalline muscovite fillers. On the contrary, after heat-treated at 1000°C, the flexural strength is increased. Scanning electron microscopy illustrated the microstructure evolution of the composites at elevated temperatures.

The role of microcrystalline muscovite to enhance thermal stability of boron-modified phenolic resin, structural and elemental studies in boron-modified phenolic resin/ microcrystalline muscovite composite

Abstract A polymer matrix composite was prepared by incorporating microcrystalline muscovite fillers into a boron-modified phenolic resin. Thermogravimetric analyses indicated that microcrystalline muscovite significantly enhanced the thermal stability of boron-modified phenolic resin under air atmosphere. Then the composite was heated in a furnace. After heated, the homogeneous structure of the composite was converted into a layered structure with a ceramic shell on the surface. The layered structure was investigated by electron probe micro-analysis and energy dispersive spectroscopy. The elemental content and chemical binding state of the layered structure were investigated by X-ray photoelectron spectroscopy. On the surface, the reaction between SiO2 and Al2O3 occurred, thus microcrystalline muscovite fillers were transformed into mullite shell. The mullite shell could protect char from further oxidation at elevated temperatures. Therefore, a amount of reserved char could react with SiO2 to generate Si–C bond in the inner of the composite.

Micro-structural and elementary evolution of a muscovite/boron phenol-formaldehyde composite at high temperatures

Abstract A muscovite/boron phenol-formaldehyde composite is prepared by compression moulding. After 10 min pyrolysis at 1000°C, it was still stable with a thermal residue value of 77.8%. The surface of the thermal residue was covered by shell-like coatings that may protect interior materials from further oxidation and decomposition, according to the scanning electron microscope and energy dispersive X-ray investigations. Also, a thermogravimetry analysis study showed that the muscovite/boron phenol-formaldehyde composite has much higher heat-resistance than pure boron phenol-formaldehyde. In addition, X-ray photoelectron spectroscopy characterisation suggested that the percentage of carbon in the thermal residue exceeded in the muscovite/boron phenol-formaldehyde composite. This suggested that most of the carbon was reserved and the carbon framework was well protected. Further analysis revealed that nearly half of the boric oxide, alumina and silica in muscovite/boron phenol-formaldehyde composite were reduced to boron nitride, aluminium and silicon carbide, respectively, after the pyrolysis.