Solidly mounted film bulk acoustic resonator (SMR-FBAR) is a breakthrough technology being developed recently in the field of electronics industry and has many excellent features, such as operation frequency of above 2 GHz, ultra-high Q factor and durable mechanical property, etc. The unique features of the SMR-FBAR make it not only be a hot spot in labs, but also attractive in particular applications. For instance, SMR-FBAR can be used to create the essential frequency shaping elements found in the third generation of wireless communication systems, including filters, duplexers, and oscillators. Materials are the key element in devices and their quality plays a critical role in determining the resonance characteristics of these acoustic resonators. In this paper, with the clue of the structure of device, the recent developments of materials used for solidly mounted film bulk acoustic resonators are reviewed, including piezoelectric films (AlN, ZnO, etc), high/low acoustic impedance materials and electrode films. The relationship between material properties and device performance is also discussed. Finally, the potential development direction on the investigation of materials used for solidly mounted film bulk acoustic resonators is prospected.

The effects of MnO₂ addition on the sintering temperature, microstructure, dielectric, piezoelectric properties and the temperature stability of PbZrO₃-PbTiO₃-Pb(Fe_2/3W_1/3)O₃-Pb(Mn_1/3Nb_2/3)O₃-BiFeO₃ (PZT-PFW- PMN-BF) ceramics were investigated. The 0.10 wt% MnO₂-added PZT-PFW-PMN ceramics sintered at 950℃ exhibited the favorable piezoelectric and dielectric properties, which were listed as follows: ρ=7.78 g/cm3, d₃₃=394 pC/N, K_p=0.54, Q_m=1180, ε_r=1480, △f_r/f_r25℃=1.68 % and △K_p/K_p25℃=-1.06 %, respectively.

Based on a modified shell model, the strain-polarization coupling was studied by molecular dynamics simulations. Using DL_POLY software packages, the lattice constant and spontaneous polarization were calculated and the results were in good agreement with experiments. The polarization switching process and the filed induced strain effects were further simulated. The results clearly suggested the existence of strong strain-polarization coupling effects in BaTiO₃. Finally, the dependence of polarization on the strain was studied. Under compressive strain, the spontaneous polarization increases almost linearly with increasing strain. However, under tensile strain, the polarization decreases rapidly. When the biaxial tensile strain ε_s reaches 0.8%, the polarization along the c axis disappears and a non-zero polarization value exists along the a axis, indicating a 90^。rotation of the polarization.

Epitaxial BiFeO₃ nanoislands were fabricated on SrTiO₃ (100) single crystal and Nb-doped SrTiO₃ (100) single crystal substrates by chemical assembled method. Their phase structure and morphology were characterized by X-ray diffraction, scanning electron microscope, and atomic force microscope, respectively. The results showed that epitaxial BiFeO₃ nanoislands could be obtained by post-annealing in the temperature range of 650-800℃, and their lateral sizes were in the range of 50-150 nm and height of 6-12 nm. With increasing the post-annealing temperatures, the morphology of BiFeO₃ nanoisland in the (100) growth plane evolved from tri-angle to square, and then to long rod shape. By using piezo-force microscope, ferroelectric characteristics of single epitaxial BiFeO₃ nanoisland grown on Nb-doped SrTiO₃ (100) single crystal substrates with lateral size of about 50 nm and height of 12 nm was characterized. The results demonstrated that fractal ferroelectric domains existed in the single BiFeO₃ nanoisland, and self-biased polarization effect was also observed within the nanoisland. This phenomenon was ascribed to interfacial stress caused by the lattice misfit between the BiFeO₃ nanoisland and the SrTiO₃ single crystal substrate.

High homogeneity heavily MgO-doped lithium niobate (MgLN for short) single crystals were grown by Czochralski method. The as-grown crystals were poled at high temperature, so as to obtain single ferroelectric domain structure. UV absorption edge, OH absorption peak, optical homogeneity of the crystal were tested, respectively. Micro- compositions along the radial direction were analyzed by EDS method and “line scan” of the distribution of Mg element along the radial direction was investigated by WDS method. The results showed that high homogeneity MgLN crystals were obtained with proper starting composition and improved growth process of Czochralski technology. UV absorption edge at 308 nm and OH absorption peak at 2828 nm were observed. The optical homogeneity Δn<5.11×10^-5. Finally, ferroelectric domain structure was observed by optical microscope by chemical etching method. High uniformity single ferroelectric domain structure was obtained by applying an external electric field at 1200℃.

Multiferroic Bi₅Fe_1-xCo_xTi₃O₁₅ (x = 0~0.6) ceramics were prepared using solid state reaction method. XRD pattern confirmed the single phase in all prepared samples and Raman scattering technique was also used to study the crystal structure. The remanent magnetization (2M_r) is increased to a high value of 2.3 mA·m²/kg with the cobalt content of 0.5. This value is two orders of magnitude greater than that of non-doped one. The promising ferromagnetism is attributed to the coupling arising from local Fe-O-Co clusters as well as the influence of net magnetic moment of Fe-O-Co clusters on the magnetic behavior. The remanent polarization (2P_r) is increased by a small amount of cobalt of 0.1, then decreased with further doing of cobalt up to 0.4, after that, 2P_r is increased again up to a cobalt content of 0.6. The dependence of 2P_r on cobalt content is attributed to the joint effect of lattice distortion, charge compensation and the change of covalent bonding condition.

Ni(OH)₂ particles were successfully prepared with Ni(NO₃)₂·6H₂O as the raw material and CO(NH₂)₂ as the precipitation agent by microwave-assisted hydrothermal method. The obtained Ni(OH)₂ were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electrochemical measurements. XRD results showed that the as-prepared Ni(OH)₂ particles had the typical α-phase. The SEM images revealed that the synthesized α-Ni(OH)₂ particles were well dispersed and ball-flower like with diameters of 0.5-3 μm which consisted of the aggregated flakes. Electrochemical properties were studied by cyclic voltammograms (CV) and galvanostatic charge-discharge tests in 6 mol/L KOH electrolyte. All the tests showed that the reactants ratio affected the morphologies and the electrochemical capacitance of the materials. When the molar ratio of the CO(NH₂)₂ to Ni(NO₃)₂·6H₂O was 3:1, the obtained α-Ni(OH)₂ had the maximal initial special capacity; when the molar ratio was 2:1, the α-Ni(OH)₂ had the best cycle storage performance.

The Y_0.5Gd_0.5BCO film was successfully fabricated by fluorine-reduced MOD method through dissolving Gd(CH₃COO)₃ into the precursor solution. As a result, Y was partially substituted by Gd and all the films have well c-axis orientation. By comparing the superconducting properties, it is found that the Y_0.5Gd_0.5BCO film has lower critical transition temperature Tc (90.5K) than that of the pure YBCO and GdBCO films. Yet the Y_0.5Gd_0.5BCO film has the highest critical current density Jc value about 4.87MA/cm² at 65K and self-field. In addition, the Jc value of Y_0.5Gd_0.5BCO film is enhanced significantly as increasing the applied magnetic field. The Jc value of Y_0.5Gd_0.5BCO film is 1.8 times and 5.1 times of that of the pure GdBCO and YBCO films at 65K and 3T applied field, respectively. Furthermore, the pinning force of the Y_0.5Gd_0.5BCO film is effectively improved by the elemental substitutions.

Mesoporous silica fibers were prepared within porous anodic aluminum oxide membrane (AAO) using a simple Sol-Gel method. The sample was characterized by SEM, XRD, nitrogen adsorption-desorption and TEM. The diameter and the length of the mesoporous silica fibers are depend on the pore diameter and thickness of AAO membrane, respectively. The orientation of the nanochannels in mesoporous silica fibers can be readily controlled by changing the aging environment. For the samples aged with the presence of water, all the nanochannels in the silica fibers are found to be circular around the fibers. However, for the samples aged without water, the nanochannels were found to be parallel along the fiber axes.

Continuous silicon carbide (SiC) fiber with carbon coating was fabricated by three-stage chemical vapor deposition (CVD) on tungsten filament heated by direct current (DC), using CH₃SiCl₃ +H₂ as gaseous reactant for SiC sheath and C₂H₂ for the outmost carbon coating, respectively. Microstructure of the SiC fiber was examined by X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscope and transmission electron microscope (TEM). The results show that the SiC fiber consists of tungsten core, a W/SiC interfacial reaction zone, two layers of SiC with total thickness of 41μm and an outermost carbon coating of about 2 μm in thick. The deposited SiC is mainly composed of beta-SiC, and exhibits strong <111> fiber texture with abundant growth defects, such as co-deposit of free silicon and stacking faults, leading to the lattice imperfection of the SiC sheath. Raman spectrum indicates that the outmost carbon coating decomposed from C₂H₂ involves a mixture of amorphous carbon and graphite crystallite.

The discrete element model (DEM) of SiC ceramic material for pre-stressed machining was established by using a cluster method. The processes of crack propagation on different pre-stressed machining conditions were investigated by means of DEM simulation and scratching test. Damages and cracks of surface/subsurface were also observed. Both DEM simulations and experimental results showed that, while the magnitude of pre-stress was controlled in a certain range, the number of radial cracks reduced as the increasing of pre-stress magnitude; and there was a trend that the radial cracks were replaced by the transverse cracks, so as to the SiC materials were removed in the form of smaller fragments. It could be seen that machining damage was decreased and surface quality was improved by applying the pre-stressed machining method, and it was further proved that discrete element method was feasible to simulate the machining process of brittle materials.

In order to protect carbon/carbon (C/C) composites from oxidation at high temperature, a nano SiC_n-MoSi₂  coating was prepared on SiC pre-coated C/C composites by novel hydrothermal electrophoretic deposition. The phase compositions of the as-prepared coatings were analyzed by XRD, the morphologies of the multi-layer coatings were observed by SEM and the high temperature anti-oxidation properties of the multi-coatings were investigated by isothermal oxidation test. The influence of hydrothermal electrophoretic deposition voltage on the phase composition, microstructure and high temperature oxidation resistance of the multilayer coating were particularly investigated. The invalidation behavior of the coated sample during the thermal cycle process was analyzed. Results show that the outer layer coatings are mainly composed of β-SiC and MoSi₂ phases. The thickness, density and anti-oxidation properties of the SiC_n-MoSi₂ coating are improved with the increase of deposition voltage from 100V to 180V. However, cracks are observed at a high deposition voltage (220V) and the decrease in oxidation resistance is detected. The multi-layer coatings deposited at 180V exhibit excellent oxidation resistance ability, which can effectively protect C/C composites from oxidation in air at 1500℃ for 346h with a weight loss of 1.41%. The failure of the coating after 80 thermal cycles between 1500℃ and room temperature is due to the generation of cross-cracks in the coating during the test.

Al/Cr₂O₃ composite particles were prepared by co-precipitation method. Effects of reaction time and calcination temperature on phase composition and morphology were studied by TG-DSC, XRD and SEM. In addition, the infrared emissivity and the reflectivity of Al/Cr₂O₃ powders with different aluminum contents at the wavelength of 1.06 μm were also discussed. The results show that the Al/Cr₂O₃ composite particles with 50wt% aluminum is well coated after reacted for 2h and calcined at 400℃.The optimized Al/Cr₂O₃ composite particles exhibit dark green appearance for visible light stealth, low emissivity of 0.66 for infrared stealth and low reflectivity of 0.41% for strong laser absorption at the wavelength of 1.06 μm.

Fe, Ti and Al-Ti binary-doped Cr₂O₃ pigments were prepared by solid-phase synthesis process. The phase structure, visible / near-infrared reflectance (NIR), color parameters were tested and characterized by X-ray diffraction (XRD), UV/VIS/NIR spectroscopy, Color CIE Chromaticity analysis software. The correlation between NIR reflectance, color and pigment structure features of doped Cr₂O₃ pigments was initially discussed. The results showed that all doped Cr₂O₃ had a single-phase corundum structure. However their grain sizes varied with doped elements relative to the undoped Cr₂O₃. It was found that the NIR of doped Cr₂O₃ decreased with adulteration of Fe but increased significantly with adulteration of Ti. For Al/Ti binary-doped Cr₂O₃ pigment with composition of 3.4wt% Al(OH)₃ and 1.07wt% TiO₂, the average reflectance in the wavelengths ranging from 700-2500 nm and maximum reflectance at 2500nm were 87.5% and 99%, respectively. The significant NIR enhancement of Ti-doped Cr₂O₃ was attributed to its larger grain size and change of Cr³⁺ local electronic environment.

The crystal growth, thermal and polarized spectroscopic characteristics of Nd³⁺:LiBi(MoO₄)₂ crystal were investigated. The Nd³⁺:LiBi(MoO₄)₂ crystal up to 15mm×25 mm was grown by Czochralski technique. The specific heat is 0.32 J/(g·K) at 330K. The thermal expansion coefficients for c and a axes are 2.767×10^-5/K and 1.521×10^-5/K, respectively. The absorption cross sections are 5.04×10^-20 cm² and 8.35×10^-20 cm² at around 806 nm with the FWHM of 15 nm for σ-polarization and π-polarization, respectively. The emission cross sections are 1.325×10^-19cm² at 1062nm for σ-polarization and 1.937×10^-19cm² at 1068 nm for π-polarization. Based on Judd-Ofelt theory, some spectral parameters of Nd³⁺:LiBi(MoO₄)₂ crystal are obtained. The parameters of oscillator strengths Ωλ are: Ω₂ = 25.40×10^-20 cm², Ω₄ = 7.79×10^-20 cm², Ω₆ = 6.37×10^-20 cm². The radiative and fluorescence lifetimes are 198 ms and 128 ms, respectively. The quantum efficiency h is 64.64%.

In order to investigate the microstructures of nonmetallic material induced by high-speed deformation,  the high-current pulsed electron beam (HCPEB) technique was used to irradiate the single-crystal silicon. The surface microstructures induced by electron beam were studied by transmission electron microscope (TEM). The experimental results showed that a large number of defect structures were formed by the HCPEB irradiation. Among them, the typical defect structures were the parallel screw dislocations and the extrinsic stacking faults. In the meantime, the HCPEB irradiation induced high density of vacancy cluster defects. The surface stress with very high value and strain rate led to the integral shift of (111) crystal plane, which might be the dominating reason of the formation of the massive vacancy cluster defects. In addition, the mixtures of nanocrystal and amorphous in the surface of single-crystal silicon can be formed by HCPEB technique.

Cubic WO₃ films were prepared by the polymeric precursor method using ammonium metatungstate as precursor and polyethylene glycol as structure-directing agent. The obtained materials were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), energy disperse spectroscope (EDS) and high-resolution transmission electron microscope (HRTEM). The influence of calcination temperature, pH value and substrates on the structure and morphology of films was investigated. The results indicate that the surface morphology of the resulting film on FTO glass has particle of 60 nm in size as cubic WO₃ calcined at 450℃, and the films are smooth and glossy with an uniform thickness of 2.9 μm. The structures of all samples on FTO glass annealed at 450-550℃ or prepared at the different pH values are cubic WO₃. The particle size of the films decreases with the increase of the pH values. Monoclinic WO₃ is formed when the films are prepared on quartz glass and graphite substrate, indicating that the substrates have apparent influence on the crystal structure of WO₃ thin films.

In order to improve the electrochemical activity of conductive diamond-like carbon(DLC) film, platinized DLC (DLC-Pt) film was prepared by magnetron co-sputtering of graphite and platinum targets. The compositions and microstructures of DLC-Pt film were investigated by X-ray photoelectron spectroscope and Raman spectroscope, and the oxidation behaviors of glucose at the DLC-Pt film surface were examined by cyclic voltammetry. The results indicate that DLC-Pt film has more sp² carbon atoms compared with DLC film, and the redox reaction of K₃Fe(CN)₆ on the DLC-Pt film electrode is controlled by diffusion. The glucose oxidation starts at about -0.8 V on the DLC-Pt film surface without interference from urea and ascorbic acid. A linear detection range of glucose obtained on the DLC-Pt electrode is identified from 2 mmol/L to 22 mmol/L (covering blood glucose levels in diabetic patients). So the DLC-Pt film has potential application to be a glucose sensor for blood glucose defection.

To develop a potential substitute for sulfurized olefins, surface-modified borate magnesium nanoparticles (titled as T-MgBN) were synthesized. The composition and microstructures of the as-obtained samples were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray power diffraction (XRD) and transmission electron microscope (TEM). The results indicate that T-MgBN with the size of around 50 nm is amorphous, and the appearance is irregular sheet. The tribological properties of T-MgBN in base oil evaluated using four-ball tribometer show that T-MgBN has better tribological capacity in base oil than that of T321. SEM and XPS analysis of the worn surface prove that there exists a wear resistance film which contains depositions and tribochemical reaction products (B₂O₃, FeB, Fe₂O₃ and BN) on the worn surfaces.

A kind of nanostructure TiO₂ with large surface area was synthesized successfully by using mesoporous carbon as sacrificial template. The effects of annealing time on the morphologies and electrochemical performances of the as-prepared samples were studied. The as-prepared material was characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), High-resolution transmission electron microscope (HRTEM), Nitrogen adsorption and desorption experiments and electrochemical measurements systematically. The results show that the as-synthesized TiO₂ is composed of nanoparticles, which has a narrow porous distribution with high specific surface area. It is also found that the sample synthesized at 500℃ for 2 h is pure anatase TiO₂, when the sintering time is prolonged to 12 h, there is a trace amount of rutile phase coexisted with the anatase phase. However, the sample sintered for 12 h exhibits higher initial capacity than that of the sample sintered for 2 h, which may be caused by different crystallization of samples.

A nanosized reverse microemulsion reactor was designed for the fabrication of monodispersed SnO₂ nanosquares by oxidation of SnF₂ under hydrothermal conditions. As-prepared samples were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and high resolution transmission electron microscope. The results show that the morphology of the SnO₂ nanocrystals can be controlled by regulating the amount of the used oleylamine which direct influenced the pH values of the aqueous phase. Well monodispersed SnO₂ nanosquares with the size around 10nm can be obtained. A proper pH value could benefit the oriented attachments of the crystalline seeds which gradually grew into a square-plate NCs shape in the microemulsion reactor.